Omc 140hp cross flow

[Jimmybar]

Need feed back on some things , any comments welcome ,1.6 L cross flow block stock bores , 140 specs , targeting 6000 rpm Max. 5300 cruise ,pushing an impeller pitch 14/22 1:1ratio bolted to a turbojet drive ,first question , scallop piston skirts vs piston windows , pro and cons . Piston skirt scallop reduces induction compression timing is there a better way , piston porting opens transfer port area much before bottom skirt on rise to tdc , then the skirt being full length still gives Max induction pressure at bdc You rarely see this MOD , we have used piston ports on v6 cf with excellent results giving 7600rpm on a 30"chopper dancraft hull , allways accused of cheating , these were slots on the piston side ( nothing new ) but I'm thinking holes low on the piston skirt matching the ports , why is this MOD no popular , ???? After all it's the same motor as a " clip on , !! Regards Jimmy .

[71V153]

Makes perfect sense to me. Go for it!

[powerabout]

Need feed back on some things , any comments welcome ,1.6 L cross flow block stock bores , 140 specs , targeting 6000 rpm Max. 5300 cruise ,pushing an impeller pitch 14/22 1:1ratio bolted to a turbojet drive
,first question , scallop piston skirts vs piston windows , pro and cons .
Piston skirt scallop reduces induction compression timing is there a better way ,
piston porting opens transfer port area much before bottom skirt on rise to tdc ,
then the skirt being full length still gives Max induction pressure at bdc You rarely see this MOD , we have used piston ports on v6 cf with excellent results giving 7600rpm on a 30"chopper dancraft hull , allways accused of cheating , these were slots on the piston side ( nothing new ) but I'm thinking holes low on the piston skirt matching the ports , why is this MOD no popular , ???? After all it's the same motor as a " clip on , !! Regards Jimmy .

Yes I would like to know about scalloped pistons or ports in the piston and cylinder wall

[spybot]

I'm thinking holes low on the piston skirt matching the ports
Can you tell us more about this mod ?

[Jimmybar]

Well ,,,this is the story, as most old skool racers know , factory mods would be leak out and everybody gets enough HP gain to get excited , it's only my option , but scallop the piston skirt is one of them ,,mercury did the same , but let me take you back 105years ago yes in 1905 a fellow developed a cross flow engine that out performed any four stroke in the time in power that's is mid range power and economy , bit like a fairy tale , it was a Scott squirrel , latter to be a Scott silk renowned for smooth power band and lots of it ,..
Up to 6000 rpm , back to the thread , in my wrecking yard is a omc factory v6 race block complete with six pac carb configuration , produced 8000rpm awesome piece of carburetor brilliance , short story , we had to carry twice as much fuel to run it weight penalty cost us in speed , ,,, Back to the drawing board , in our case the shed and beer fridge , so we .in our drunken wisdom came up with the theory that if you increase air velocity to a point were it has to go somewhere why not shoot in straight to the crown of the piston in two directions then give it Max induction pressure , that's a rough explanation, hence send the gas up the transfer port , at the same speed , keeps the piston and rings happy to. Never had engine fail , would go day racing on Sat the social ski on sun. Good thing , the same MOD produced nearly the same rpm and horse power as the factory MOD , the only reason I'll bring this to you is that someone one your forum produced a pic of the same MOD , great minds think alike , has anybody tried this on a v4 ???

[powerabout]

These photos belong to other members posts, hopefully they will jump in

[racer]

Powerabouts photo on the right is the best combination for power. Finger ported with scallop and post hole.

[Jimmybar]

Would like to post a pic , need help , thanks

[Jimmybar]

What's your assessment for the piston on the left ??

[powerabout]

Powerabouts photo on the right is the best combination for power. Finger ported with scallop and post hole.
Hi Racer
What should the port in the cylinder wall look like, just a round hole or a slot?

[FMP]

Something like this?

[powerabout]

interesting, finger ports to meet up with the original ports?

[racer]

Round hole

[Jimmybar]

Great mods , what do you suggest for my v4 5300rpm cruise 6000rpm squirt , ??

[powerabout]

All depends on boat weight, the fuel you can get and what you do with the boat.
Setup and prop is your best return re simple and reversable.
How fast and what prop do you have now

[powerabout]

405910
What RPM does this mod work at?

[racer]

Never found cutting the slot back more than the reeds cages to help.

[Jimmybar]

We're talking in board jet. Omc turbojet to be precise , I've pitched the impeller from 10/20 to 14/22 the difference took advantage of low to mid range grunt from the 140 cross flow striped on top. The boat weight varies 450kg to 750kgs loaded , ,catch tanks full cool boxes full , plus two blobs. The boats current top speed is 42mph. @ 5500rpm , best cruise speed is 5300rpm gives best economy,the engine is a bit tired. Now doing a rebuild , and need a bit more zing. It's a touring boat used for fishing hunting. Gets a ship load of camping gear thrown in , and sit at speed sometimes 2-3 hours at a time , I think that's it

[71V153]

In my humble opinion. Lose the jet drive and bolt a gearcase on!

[Jimmybar]

Yes, yes , I'm hearing ya , it's a choice of survival. I've got a pallet loaded of busted gearboxes bent shafts , destroyed mid sections , but guess what no jetdrive bits , I realise there not the most efficient drives , but they slide over things like logs and rock shelves ,all hiding just below the surface , I need to build this motor to the equivalent performance for a barge. The pump is a steady load , drops 100rpm in turns that's it , just want 6000 rpm tops , I can do the port matching , 135PSi ,suffers , I'm just unsure about the scallop piston MOD , racer gave good feedback on piston mods , but I'm not going for the screamer , I need to move a mountain with mid range grunt , any help appreciated, regards Jimmy

[gmjim]

What's the story in your Dancraft Jimmy?

[Jimmybar]

It's long gone , it belong to a now life long friend , I helped him develops the attitude of the boat and engine to suit his purpose , it was bought as a drag race , we took delivery of the boat with a video, where the boat was clocked at 105mph at Windsor , so we got to work on it for bridge to bridge ski race , with two dags in tow , we manage to maintain 105 mph with the skiers, in that time we meet some awesome people , with many life changing experiences , latter did quarter mile drag ski racers , now that was fun , our success was base on truck engine mentality, , focus ed mainly on torque curve performance , that was our strength " acceleration" we made a bit of money on the side blowing off 454 Chev's , the only ones that beat us had a blower on top , very competitive , great times. I can delve into engine mods , but that's another story ,cheers , Jimmy

[Jimmybar]

Should mention , it was a dancraft "firefly , light deck with a 235 HP erude

[racer]

For what you are doing with the engine IMO do a good general clean up and you should gain the rpm you are looking for while not hurting durability.

[powerabout]

Should mention , it was a dancraft "firefly , light deck with a 235 HP erude
what size Dancraft?

[Jimmybar]

Firefly was ,16'7" blue with white deck , we put 6" ribbons as tell tales across the deck to measure positive negative pressure , save my ass from blow out a couple times ,

[powerabout]

Pretty rare to find a jet ouboard in OZ, I didnt think they were ever marketed?

[Jimmybar]

Search "turbojet" on your side of the pond , " sugar sand mirage ," ,X Boston whaler" to mention a few ,, hard facts , are hard to find , suspect this arm of omc put this to purpose ,not only as position to mercury spotjet , I feel shareholders wanted something at the table when bombardia come on the scene , that's is speculation , would love to know the facts , it's very interesting , did you know , inboard jet units are 1:1 efficiency with clip ons between 35mph .. 45mph , that's a fact ,regards Jimmy

[Jimmybar]

Have got a very tidy 90HP block with good bores ,spent last night in machine shop opening up ports and milling exhaust slot. There's a big difference , between a 90 and 140 ,especially the port heights ,and diameters , all done ,

[nitro_rat]

Remember that old saying “a picture is worth a thousand words?”

[71V153]

Remember that old saying “a picture is worth a thousand words?”No cameras down under. I reckon ...

[nitro_rat]

No cameras down under. I reckon ...

Maybe they do have cameras...

Is that why some guys pics come in upside down?

[Jimmybar]

Very funny dudes , I'll try and send some pics ,

[Jimmybar]

Comes up with I do not have permission to access this page , try again latter on laptop ,

[Umassot50]

If you really want to get wild I can make you one of these.

https://www.screamandfly.com/showthread.php?261673-OMC-Xflow-V4-horizontal-intake-and-other-modifications&highlight=Horizontal+intake+xflow

[DanUmbarger]

What ever happened with your Xflow build?



If you really want to get wild I can make you one of these.

https://www.screamandfly.com/showthread.php?261673-OMC-Xflow-V4-horizontal-intake-and-other-modifications&highlight=Horizontal+intake+xflow

[Umassot50]

Never finished it. Too much other stuff going on.

[DanUmbarger]

Too bad...looked very interesting!!!




Never finished it. Too much other stuff going on.

[Umassot50]

Too bad...looked very interesting!!!


I will at some point. Changing some things.

[DanUmbarger]

:thumbsup:


I will at some point. Changing some things.

[Jimmybar]

406253that's a crossflow

[Jimmybar]

here's a few more , just to get you excited ;;406254406255406256

[Jimmybar]

here's a few more , just to get you excited ;;406254406255406256

[Jimmybar]

what's the story behind these omc bits . there's a part number . a production number . just interested in there history////??? regards Jimmy

[Jimmybar]

here's a clue ." it's a tripple "C" block .

[Jimmybar]

ahhhh , just been reading another thread on OMC history , the CCC block was well suppored by F1 racing. No wonder we kicked ass at social level . would make a good coffee table ,thanks for your advice on mods .will keep you posted on progress. cya

[71V153]

Umm, that's not a 140 crossflow?

[powerabout]

I wonder if a small bore CCC made same hp per cylinder as a KR 15?

[Jimmybar]

its a CCC small bore race block. just spent time in your history books . great read . racer had a bit to do with em , its gunna be a coffee table . theres no doubt its a crossflow combustion chamber , and remember "DANGER IS INEVITABLE ,,FEAR IS OPTIONAL "have a good one gents ,cya

[Jimmybar]

its thats.s all it takes to stump you blokes ,, might try another thread get motivated ,,,,,,jimmy

[BarryStrawn]

Pictures from when you used to run it are probably more interesting to most of the folks here. Kind of disgusting to see it in that state of neglect.

And the model is NR-19S. CCC was the Evinrude decal and RS for Johnson.

[Jimmybar]

your right Barry, its been laying around for years in the farm shed . would love to do a" cut and display" the workings of a crossflow two stroke for educational purposes , its up for grabs if anyone is interested.its a fair lump of alloy to send O/S ,if there is any interest in OZ , let me know. I'm not one to be emotional attached to old machines, but I respect your view.cheers; P.S thanks for the model numbers . I'll stamp them on a plate and attach,

[powerabout]

I'd be interested if nobody else in OZ is?

[Jimmybar]

powerabout;3041350]I'd be interested if nobody else in OZ is? I;m 6.5 hours north of Melbourne . If your location is anything to go fromm ???? make an offer ,

[Jimmybar]

just for interest : here are some port timing figures. v4 90 hp IN. 2.170",,,,EX 1.805" ///// v4 140 HP. IN.2.100" EX 1.760" ////v6 200hp IN 2.125 EX 1.625"//// v6 CCC smallbore hp?? IN 2.00" EX 1.575" .there is a definite pattern here. Feel free to add to this , regards Jimmy

[powerabout]

did this configuration work well?
Thanks to fellow S&F'r for the photo

[Jimmybar]

nice piece of engineering. is blessed by the" KISS " method ,

[racer]

CCC came with different carbs than pictured.

[Jimmybar]

Thanks Racer ,your on to something there . we ran that block for a while . the acceleration was breath taking . straight to 7800 rpm . thats with scolloped pistons and cylinder wall skirts cut . factory mod .we were led to believe... how ever we pushed it to 8000 rpm with the slotted piston ports and cylinder wall slots to match. we also tried other block configurations ... and came to the conclusion there's a dozen ways to skin a cat . choose one , we had three different modifications all producing close to the same result . have you seen this in your time ???

[71V153]

Actually there's only one correct way to skin a cat ...

[powerabout]

Thanks Racer ,your on to something there . we ran that block for a while . the acceleration was breath taking . straight to 7800 rpm . thats with scolloped pistons and cylinder wall skirts cut . factory mod .we were led to believe... how ever we pushed it to 8000 rpm with the slotted piston ports and cylinder wall slots to match. we also tried other block configurations ... and came to the conclusion there's a dozen ways to skin a cat . choose one , we had three different modifications all producing close to the same result . have you seen this in your time ???
Did you add slots to block that already had a scallop?
what was the 3rd solution?

[Jimmybar]

go back to the pictures of the two pistons , on right is your performance screamer everybody loves, not much talk about the piston on the left, that's very much like ours. with the cylinder wall slots to match. this gave us best revs. especially with that CCC manifold . however it was boggy down low <2000 rpm , if RACER could elaborate on the correct carbs for that CCC manifold,, that would be something. also did OMC ever make the CCC manifold to fit a V4. ??? now that would be something !!!! then there's the 3rd option,,,,,,,,

[Jimmybar]

did we add slots to a scolloped block ,,NO,, the slots lets the charge take a more direct line to the inlet port, while the piston crown does all the pumping.this advantage is notice by most engine tech heads examples everywhere from scollops to slots to carbs directly to intake tracks. the bottom line is "charge efficiency" combustion scavenging and exhaust are in the equation, most important to me is the frequency pulse of the engine . we use to measure it with oscilloscope , then some smarty pants said. get with it old farts , mechatronics, Well some old farts have a pitch perfect ear for motors. which system is the proper way??? , ,,,,,depends on your choice , cheers Jimmy

[FMP]

Did you extend the slots right to the bottom open to the crank case or only fed through piston slots?

[Jimmybar]

There's an old v4 block under the bench . I'll do the same mod to it and try and post a pic would that help??

[FMP]

I thought you meant something like these above. I wouldn't want you to go cut on a motor, that's above and beyond.

[Jimmybar]

407204407205Ok , 5 mins on the die grinder, piston on the right is the v4 slotted version v6 version has 3 slots, piston on the left is mid range power mod ;note the piston at TDC gives max, port opening on tdc charge. this will go into the turbojet project,,,thats not the finished port job , might post that latter,

[FMP]

Surprised you didn't increase port area squared to take advantage of max scavenging duration while slots are open.

[Jimmybar]

t407206this one is for barry,

[Jimmybar]

Surprised you didn't increase port area squared to take advantage of max scavenging duration while slots are open.
as stated ..."this is not the finished port job " might post that latter. might !!

[FMP]

I thought back when , not what's coming. Thanks for sharing:cheers:

[71V153]

Lookin purty gnarly. Following.

[FMP]

Want to see the flip side now.

[BarryStrawn]

t407206this one is for barry,

Looks good. Is that a V hull?

[Jimmybar]

yes it was . on the Dancraft "Firefly"; check out previous post. that motor was a thing of beauty >>>>>

[gmjim]

Hey i think we need put this motor back together and put it on my firefly!!

[Jimmybar]

gmjim 8000rpm would be a new name !!!

[Freddie Webb]

How much for the Ccc front half , reed cages and carbs. I'm not interested in the block

[Jimmybar]

thank's for your interest . I'll put you on the list .

[Jimmybar]

t407206this one is for barry, well it would seem this photo is a bit popular . now seen it's on a few other boat sites . posted by people viewing . so perhaps we'll use that to pass on a bit of "old feller majik." when it comes to dealing with salted outboards . How many times has the bolt snapped off clean and how do you fix it . How DO you fix it . have heard some heart break solutions . Apparently there's only one proper way to skin a cat . I would not agree with that . however an open mind is in order. I've just stripped several bolts on this 140 hp head cover plate and thought I'd share what I believe to be the 100% method to remove broken bolts . would love to hear the proper way , will share some pics if you share some tips . its a win win . cheers JIMMY

[powerabout]

heat and ultrasonic cleaner?

[Jimmybar]

heat and ultrasonic cleaner?can you run me through the proceedure please .

[powerabout]

https://www.unisonics.com.au/?gclid=EAIaIQobChMIg-fmuP-N2wIVgzUrCh0l8Qc3EAAYAyAAEgKsKPD_BwE

if your not cleaning carbs in a ultrasonic tank, your doing it the hard way

[nitro_rat]

You can pick up a “jewelry cleaner” at harbor freight for peanuts...

[Jimmybar]

407757407758407756It's old skool . but it works . no heat signature .

[FMP]

Lefty loosey Righty tighty !

[DanUmbarger]

That's how I remove broken bolts in many of the old Suzuki outboards...my welder welds nut to the broken bolts and heats up the block/head or whatever has the broken bolt in it and turns them right out...have had many done.



407757407758407756It's old skool . but it works . no heat signature .

[powerabout]

thats the omc factory recommended way as well

[Jimmybar]

thats the omc factory recommended way as well never new that ... I don't heat the parent metal . just build on the broken stud with the mig , making sure it soaks down the stud . then place nut over the top . couple taps with hammer . plug weld nut . let it cool a bit the give her a twist . most times frees first up . if not . wind it off and repeat process .very useful if the motor is still in service .. in 50 years building twostrokes never beaten with this system. just sharing tips .cheers Jimmy

[powerabout]

whats with the red coating?
Are they heads from a 115 turbo jet, how does the combustion chamber look?

[Jimmybar]

The red coating is just high temp. engine enamel . Not my preferred corrosion protection. I don't have any Adoline . If you could tell me what paint and process OMC use on those old v6 water ways . that would be a big help. The heads are off a 140 clip-on I picked up in my travels. yes there going on the turbojet re-power . Would like to see 130 -135 psi compression . when strapped on , they will be run at near wot most of the time and loaded so pre-ignition points have my attention . jump in and add to that if you like . any tips are good tips . here's some pic's 407987407988ready for the oven @90 C*

[nitro_rat]

Hi-temp engine paint has ceramic particles in it and is an excellent insulator! Not what you want in your cooling passages!

[Jimmybar]

Hi-temp engine paint has ceramic particles in it and is an excellent insulator! Not what you want in your cooling passages!what can i use instead ?????must have corrosion protection

[nitro_rat]

what can i use instead ?????must have corrosion protection

The least insulative paint you can get will be something thin, flat black, and without ceramics (no engine paint or BBQ paint)! I like thinned rustoleum, cut about 50/50. Heat the part lightly, brush on THIN coats. Let them dry in between. May take a few coats to get full coverage but don’t overdo it! Make sure to cure it out before use. A lamp in a foil lined box or the shop oven on low heat will cure thae paint fully. It will be hard and as thermally invisible as paint can be.

[Jimmybar]

thank's mate .you advice will be used.

[Jimmybar]

408090408091this is mainfold 1300 c* coat . Are we good to go !!!!!

[Jimmybar]

one thing leading to another . Is there a dead zone with flywheel harmonics ?????

[powerabout]

one thing leading to another . Is there a dead zone with flywheel harmonics ?????
v4 even fire, I doubt it

[Jimmybar]

v4 even fire, I doubt it I'm using a standard crank' and flywheel . Have heard 6200 rpm ---6400rpm is the dead zone for v4 crossflow . correct me if im wrong . thank;s . the way this build is starting to pan out . It's something to be aware of , that's all ., any tips appreciated .

[powerabout]

I'm using a standard crank' and flywheel . Have heard 6200 rpm ---6400rpm is the dead zone for v4 crossflow . correct me if im wrong . thank;s . the way this build is starting to pan out . It's something to be aware of , that's all ., any tips appreciated .
never heard that, the v6 being an oddfire engine had an issue at 6400 I think.
stock 77 140 would happily run into the mid 6000's on a light boat.

[DanUmbarger]

I've heard that also...stay below 6200 or above 6500...something about harmonics I believe. I have a 1975 135 Johnrude and I'm going to try to run it at about 6000.



I'm using a standard crank' and flywheel . Have heard 6200 rpm ---6400rpm is the dead zone for v4 crossflow . correct me if im wrong . thank;s . the way this build is starting to pan out . It's something to be aware of , that's all ., any tips appreciated .

[racer]

Its the V6 that has a 62 to 6400 harmonics never heard of that on a V4 and ran them at that RPM a lot.

[olboatman]

Scribed

[Jimmybar]

hmmmm? might send the flywheel off to speed shop and check balance . $50 insurance . thank's for advice gentlemen ,,, stripping carbs while J B weld is curing on inlet manifold will post pix soon . J

[powerabout]

hmmmm? might send the flywheel off to speed shop and check balance . $50 insurance . thank's for advice gentlemen ,,, stripping carbs while J B weld is curing on inlet manifold will post pix soon . J
make the rods and pistons weigh the same

[Jimmybar]

make the rods and pistons weigh the same
with the rods I balance the little ends first on a pivot , then adjust the big ends, to 1gr... the pistons,,,will check squish zone with plastsine ,then going to cut the skirt to allow for max intake to the crown at TDC and wide enough to allow for the four ports to take a breath . bit different to a scallop on the 9 pages..then take them to within a 1gr as well , somewhere near the mark ???

[powerabout]

I was thinking to get the slide rule out and see the area of the scallop versus slotted piston?

[Jimmybar]

I was thinking to get the slide rule out and see the area of the scallop versus slotted piston?yes , that's one part . then add induction port timing . then crankcase compression timing. add a bit of assumption on pulse timing . sprinkle with anticipation. and" whoa lah". see you on race day !!!.PS reality is . we have a passion for these old bangers . and love it .cheers

[71V153]

My Baja 15ss ran 62.9 with a stock, carbon encrusted '83 140. Bolted on the transom.

Run 66.7 with a fresh "7 1/2 paged" '77 140 on a 4" jackplate.

In retrospect. Next time I'm just gonna buy a bigger motor ...

[Jimmybar]

NOW THAT'S JUST TO EASY ..Ha Ha hahaha

[olboatman]

My Baja 15ss ran 62.9 with a stock, carbon encrusted '83 140. Bolted on the transom.

Run 66.7 with a fresh "7 1/2 paged" '77 140 on a 4" jackplate.

In retrospect. Next time I'm just gonna buy a bigger motor ...

Did you have a low water pickup on that 77 140?
Gary

[olboatman]

I should have asked where the prop shaft hight was in relation to the hull bottom?
Gary

[Jimmybar]

Did you extend the slots right to the bottom open to the crank case or only fed through piston slots?419792
ok , after much airflow testing , and with consideration to the dilemma of 1 3/8 with no performance benefits . and constant piston burns . this is what I,ve found ,
refer to 1 3/8 ' carbs post

[powerabout]

did you machine the block to match the piston?

[Jimmybar]

No . here's a pic of the 90hp block ported to 140+ hp . going into service with" mod 3 "pistons .. I did test the matching slots ,in pic 2. but found air flow much higher. but crankcase compression lower !!better suited to higher revs ,,not required.419797419798

[powerabout]

you said airflow much higher, how are you measuring that?

[Jimmybar]

Sit down, grab a beer. and get your head around this , I set up a compressed air jet into the intake duct then set a db meter at different spots . piston chamber. intake transfer. crankcase area . and measure the db sound level at different crank angle tdc to bdc . this gave me a measurable difference at different points. put that info on a graph. tried factory . 9 pages .and mod 3 . the higher the pitch and sound the faster the air , and lower db's more volume , bit out there . but so is science , its the pulse wave . that's the one . want more ???

[powerabout]

ok, I can understand that.
you said you kept burning pistons, what mod caused that?

[FMP]

Hey Jimmy,
Good stuff , too bad about the burn! Where's the burn, on deflector, all pistons. Just picking up this read again , this burn is recent?

[powerabout]

I wonder with a stock engine or even a scalloped block, can you use a bypass cover that has a floor in it to help turn the flow to 90 degrees and into the cylinder?
Now we are trying to get flow into a sharp edged port

[FMP]

I was told floor of xflow tr port should remain flat to push flow into deflector vs over shooting with ramped floor. Fresh charge aim is important for cooling the deflector

[powerabout]

I was told floor of xflow tr port should remain flat to push flow into deflector vs over shooting with ramped floor. Fresh charge aim is important for cooling the deflector
thats what I am saying, ensure it feeds in at 90 degrees direct to the deflector and not out the exhaust

[FMP]

Brain fart here but I'm use to seeing tr covers that are fully contoured to aim into the ports, OMC not?

[powerabout]

Brain fart here but I'm use to seeing tr covers that are fully contoured to aim into the ports, OMC not?
yes but what about the inside of the curve, straight up the cyl wall then sharp 90 into the port, cant be good for flow

[FMP]

Up the wall, if you want real fancy build up an area which eliminates the dead eddy stale spot just , match the cover profile closer and funnel. Wouldn't take much 1-2" sq 1/4-1/3" height patch epoxy shaped just down from the floor of the ports. Maybe it would help but it's such a stop and go flow?

[powerabout]

Up the wall, if you want real fancy build up an area which eliminates the dead eddy stale spot just , match the cover profile closer and funnel. Wouldn't take much 1-2" sq 1/4-1/3" height patch epoxy shaped just down from the floor of the ports. Maybe it would help but it's such a stop and go flow?
think about how much work punters do to the behind the liner ports on engines, yet the largest port with the easiest access has all the worst features for flow.

[FMP]

I did see a pic of a mod race CHRYSLER which had additional small 15/25hp size carbs feeding the port covers with balance tubes and can. Not sure how that worked out?

[Jimmybar]

think about how much work punters do to the behind the liner ports on engines, yet the largest port with the easiest access has all the worst features for flow.
todate I haven't burnt a piston , grabbed a few'' but lean out " Nope " I'm referring to the cautions received in this forum. now to your ."the largest port with the easiest access . " how true is that . this port;apart from a high speed puff TDC " is total underutilized in factory mod . and slightly used @12' btc in nine page mod.which losses crankcase compression .because of the scollop.. both still rely on drawing in the charge hold it in suspension under the piston' then' with compression' force it up the transfer port. its a fact of nature . if you compress air it will condensate. so if fuel is in suspension;held under the piston' then compressed ;back into the crankcase' then force into the transfer port . "which has little to no fuel charge" the fuel droplets increase in size . not what you want for efficient combustion.mod 3 draws charge into the transfer port @30' btc. moving the charge across the crown ready for its journey back into the crankcase then up the transfer port which is already charged with fuel' does it sound like it will work. ??? It would be a great test if somebody on your side of the ditch would try it ' these engines can make a lot or power for there capacity but not that great on fuel could this be it ??. nine pages has quite a reputation. is it the answer . ,,cheers

[FMP]

That's what these mods do , try to have fresh charge waiting packed at the ports when ports open. However max scavenging doesn't occur till piston is near bdc on downstroke and turning around. Your cc compression helps when increasing prior to tr port opening , working as a train of gasses right behind blowdown interval of cylinder and hooking up to the ex draw out the xport across the cylinder and out the transfer to the cc. The transfer floor aim should be perpendicular to the cylinder to hit and cool the deflector and force the charge to head up to the chamber. The spill out the ex should be kept to a minimum and then re packed into the cylinder by the tuning paired leading cylinders strong exhaust signal raising dynamic running pressure and maintaining the fresh charge in the cylinder. If you short circuit you increase the risk of a lean out and waist the charge.

[Jimmybar]

I'm good till the last bit , short circuit the charge. and waste the charge.I can't see how an increase in induction volume with the same stroke , using mod 3 . wastes a charge. if you've got and old piston .do the slots and see for yourself. if you still think there's no improvement with induction charge .maybe I'm on the wrong track !and perhaps vespa. scott, and others are also on the wrong track. the slotted piston, which was posted on this forum,and the reason I'm here.. is similar to this one we used an a CCC v6 works just great to 7800rpm + the system does work, your not the first to say it won't , can we put that aside,,, note the different angle of attack on the slots the v6 slots" angle out", this is for high rpm... v4 slots" angled in", this is for low rpm giving max induction . also important is the port timing . looks identical, this system was developed to run fuel injection at the transfer port and still give cc lubrication .if I can confirm the torque and hp figures then thats gives a green light to progress to that . It's my belief that loop charge engines are not the answer. they make no more power using same c. c. s ..... give me a couple of weeks to put it together and see what we got , if your still interested I'll post it. 419926419927

[FMP]

Not the piston slots but the actual transfer ports. The round holes, the floor, the sleeve and block of the port. Perpendicular to the cylinder, not angled to shoot the charge over the piston ridge. What power and I were posting just above.
Post away friend, love to see a xflow run a looper.

The pic of the transfer ports, if I zoom in and really look does the floor stay level across the sleeve and only the block is shaped below the floor, it's difficult to distinguish?

[Jimmybar]

Now were cooking !!!!!there straight in ,

[FMP]

Onward

[Jimmybar]

Not the piston slots but the actual transfer ports. The round holes, the floor, the sleeve and block of the port. Perpendicular to the cylinder, not angled to shoot the charge over the piston ridge. What power and I were posting just above.
Post away friend, love to see a xflow run a looper.

The pic of the transfer ports, if I zoom in and really look does the floor stay level across the sleeve and only the block is shaped below the floor, it's difficult to distinguish?read your post again and would like to say I agree with your discription of gas flow. as far as racing against loopers , have done that . and beat them to the line , yep done that . never seen one to happy about it . that's racing . 1/4 mile ski drag. some were mercs , they may not count, cheers

[Jimmybar]

we should be aware here that you blokes focus very much on tuning engines to perform like missiles.Where as blokes like me just want strong reliable truck engines to go fishing and boating .What I'm saying is thank's for your input and patience , it is very much appreciated . regards Jimmy

[FMP]

Probably running strong by now.

[Jimmybar]

Probably running strong by now.one more trip with old motor ....then ,THE TRANSPLANT

[powerabout]

407204407205Ok , 5 mins on the die grinder, piston on the right is the v4 slotted version v6 version has 3 slots, piston on the left is mid range power mod ;note the piston at TDC gives max, port opening on tdc charge. this will go into the turbojet project,,,thats not the finished port job , might post that latter,
I forgot to ask if you have (for the 4 port engine Stock/KR/CCC) cut the middle bridge out to make a large port, how is the result same for the exhaust, anyone?

[Jimmybar]

g'day all ,well its been a while , drought, bushfires ,covid, now floods , however the upside of covid self isolation is time in the workshop , LETS GO, 471906471907471908471909471910there's more

[LakeFever]

Just bought a stock 140, we'll see if I do some of this over time. Not in any rush got plenty to do first.

[Jimmybar]

Just a footnote to those who are new , this mod 3,, a experimental mod based on a Scott motor cycle mod in 1905, which was very successful to 1930 , performed well in racing , too well ,it was banned from racing against the same class of four strokes because of the "Unfair performance advantage ", the engine was a crossflow two stroke with a strong midrange power curve , peak revs were 5500 rpm , this is what got me in , so just because we can , I tried to replicate the same theory of tune to the omc 1600 FT engine and to my surprise it did the same to this engine , now done a dozen tanks of fuel , the engine is a stump puller , awesome hole shot fast ecceleration , but don't get to excited about revs , 5700 rpm , was hoping for a bit more , but there safe rpm , this mod is specific, pulling tubes or skiers , yes , punching heavy boats out of the hole , yes uses less fuel at cruise , definitely, high speed performance " No, " , just want be clear on that , this is a truck engine style mod , in my case the outstanding feature of this mod is fuel efficiency, I do the same trip up river , and I'm using less fuel , the saving is coming from quicker hole shot , less throttle to hold 5400 rpm , well its been a great ride , many thanks to those on line for your generous help and knowledge , also to those who have supplied some ungettable bits , this is boating , BIG THANKS , Jimmy

[FMP]

Nice !

[Schramer]

g'day all ,well its been a while , drought, bushfires ,covid, now floods , however the upside of covid self isolation is time in the workshop , LETS GO, 471906471907471908471909471910there's more

Sweet velocity stacks!! I have an update on "my" project I have been speaking with you over the last yr or so...…email me or give me a call in the next few weeks so I can go over the details with ya. :thumbsup:

[Jimmybar]

Can do , my turn to call , and the stacks ,ohhhyeah,,, there music to my ears at 5500 , the induction roar ,,makes the hair stand up on the back of the neck ,now that's boating , never did find the manufacturer , they compliment the 1 3/8 " carbs , for sure , be intouch Chad ,,,cheers James

[powerabout]

Can do , my turn to call , and the stacks ,ohhhyeah,,, there music to my ears at 5500 , the induction roar ,,makes the hair stand up on the back of the neck ,now that's boating , never did find the manufacturer , they compliment the 1 3/8 " carbs , for sure , be intouch Chad ,,,cheers James
I think Land n Sea had ones that looked like that

[Jimmybar]

couple engine bay shots , any feedback welcome471946 electric fuel pump makes start and prime easy, not that happy with fuel pump location , might need to be lower , ignition cdi bracket turn out well, older block pattern with new ignition bits , 471947

[Jimmybar]

I think Land n Sea had ones that looked like that
Your right ,,,"Bob's machine shop ", :thumbsup:

[powerabout]

you gotta get that exhaust sorted to on a jet to get the best from it.

[Jimmybar]

[QUOTE=powerabout;3228078]you gotta get that exhaust sorted to on a jet to get the best from it.[/QUOTE , yes , but how,,,this unit is 25 years old, jet units have evolved a lot , and to answer the question ,most have external exhaust systems with ecu controlling the amount of water introduced into the exhaust stream , to control pulse wave , top idea , best I can do is play with water into exhaust stream , but to change the gas flow circuit , hhmmm, big job , i did deburr and streamline the tract leading to the megaphone oulet in the exhaust muffler, giving a nice clean crisp note , though acceleration to 5700 rpm ,, exhaust gas circuit on a turbojet drive ,could have been a lot better ,this is evident in modern units having external water tune exhaust systems , like seedoo , you could go online and have a look for me , maybe different eyes see different things ,

[FMP]

Can't recall what " bubble back" is on this motor , if it's the same then ties in to that snake. Would you have enough space for a different exit from the lower bubble to a megaphone type tuner of stock length angled down and away to the stern? Then if space permits build a box around that with a clean exit out the lower transom. All sealed tight with a wet to dry water regulator washing the tuner if you like. So a welded aluminum box containing the tuner with through transom exit down low. A suitable exit transition that would flex with the powerhead movement of the box but stay fixed to the through transom. Like a 3" through hull. Just spit balling.

[Jimmybar]

Good spit, just looked up marine exhaust , to get a visual on your ideas , yep lots of options, you may have started a roll here,, now if you got some pics of exhaust systems straight off the exhaust ports , This could be what I'm looking for to go v6, keep em comin,,,,,,

[Jimmybar]

472051I love this , gets you thinking

[FMP]

Somewhere I have seen that diagram of your system, OMC paper I believe.

Somewhere pictures are posted of that system, was it you who has them?

[powerabout]

You need a kr style and mount it upsidedown.
Msd used to make a programmable water injection module

[Jimmybar]

Its is possible ,to make the v4 a screamer , but let's look at repower , the engine block is a crossflow , " we all no dat" but other engines have the same base pattern like 200 v6 , , and possibly a 90 degree 175 v6 looper of the same vintage thats 91 to 98 , question is ,, do these 90 degree loopers fit the cross flow base , if they do , then that's exciting , is there anyone ,,who can throw some light on this , ..???

[Schramer]

The loopers have a different bolt pattern but you could find a V-4 looper and adapter and bolt it right up to your current setup, with the correct hardware. Being that the out-drive is a jet, you don't have to worry about the X-Flow gearcase holding up to the looper. As long as your rig has the possibility of changing the adapter plate, you should be be able to pull it off :thumbsup: I dn't know shizzle about jet drives so I could be way off but with an outboard, it is a very doable swap.

Schramer

[Jimmybar]

Gez chad , one thing I'll hand to ya , you step up to the mark , I'll do some home work , thanks mate ,

[Jimmybar]

Went through parts lists , on v6 includes ,cross flow v6 ,and 90 degree looper , your right Chad all loopers have different base adaptor to cross flow, barking up the wrong tree ,I was , , , at least I can mount a v6 on the turbojet , or just be happy with the four , thank you for clearing that up ,

[Schramer]

I didn't know if you had a the ability or not, to change the plate on your rig. The midsection was the same for several years between the X-Flow & looper and you can mount any V-6 to almost any mid throughout the years with the correct adapter plates/gearcase. They were different between the two but I have a bad ass V-4 (small) looper case with a 2:1 ratio, that has a V-6 prop shaft fit into it & have ran it with success on the V-6's.

I have a nice V-6 X-Flow MOD that I was finishing up to sell but it is complete and I'm sure, if you were interested, you would want the powerhead only.....understandably, if you could make it work with your setup. Want it to go to a good home as I consider it a relic lol

[Jimmybar]

I didn't know if you had a the ability or not, to change the plate on your rig. The midsection was the same for several years between the X-Flow & looper and you can mount any V-6 to almost any mid throughout the years with the correct adapter plates/gearcase. They were different between the two but I have a bad ass V-4 (small) looper case with a 2:1 ratio, that has a V-6 prop shaft fit into it & have ran it with success on the V-6's.

I have a nice V-6 X-Flow MOD that I was finishing up to sell but it is complete and I'm sure, if you were interested, you would want the powerhead only.....understandably, if you could make it work with your setup. Want it to go to a good home as I consider it a relic lol
472179472180this is the limitation , unless you add an adaptor plate between engine and this , you would also need to extend or remanufacture drive connector , gets messy , a cross flow v6 would bolt on , just don't throw to much gas down the exhaust hole ,

[powerabout]

You need to mod the bubble back to allow the exhaust to exit straight out and not go down to the adapter then build the rest as well.

[Jimmybar]

You need to mod the bubble back to allow the exhaust to exit straight out and not go down to the adapter then build the rest as well.
It doesn't stop there , then , the drive is 21t 21t , omc cobra top gearbox set , gear to 21 t 19t to take advantage of extra hp , nah, going to back away from this one , stick with the v4 , nice dreamin,,

[powerabout]

It doesn't stop there , then , the drive is 21t 21t , omc cobra top gearbox set , gear to 21 t 19t to take advantage of extra hp , nah, going to back away from this one , stick with the v4 , nice dreamin,,
hot v4 will never break those gears IMHO

[Jimmybar]

hot v4 will never break those gears IMHO
That's a fact, if its one thing that's solid in a turbojet ,,the gearbox , the gears arrangement, to take advantage of hp ,increase impeller shalt speed buy selection of gear sets , 21;21 , 21; 19 , or 18 or 17 , 16 , , sport jet do a 90 hp to 240 hp on the same hull , you can never have enough hp , that seems to be the problem for "old petrol heads" l"200 v6 crossflow , 21;19 gears, water cooled expansion chamber directly off the exhaust chest , this coming together , is there any v6 exhaust chest bolt-ons out there , that would could put the project on the board , ??pics would be awesome , were probably dreaming here , or do we make our dreams come true , thanks for your input to date , its inspiring,

[Jimmybar]

How bout this one ,,!,,,!,, still looking for a suitable manifold idea , 472273472272