Ingredients to make killer 2.0

[Keaten]

Can someone school me on whats inside a F1 powerboat merc 2.0 powerhead , or maybe HP numbers at 9-11,000 rpm I want to learn as much as i can, block base 2.4 or 2.5, front half,porting numbers , compression ,lossing bottom end doesn't matter to me..

[FMP]

Someone put up the SST120 specs a while back, maybe they will repost as a start.

[Capt.Insane-o]

They are a bridgeport block, kind of their own special thing. The one I ran on my Viper came with sheet stating 312 hp at 9200. It had 180 psi. I put a spacer, pcu and cut the heads to 18cc, stock they were 21 cc.

They don't pull as hard as 2.5 but they are a wicked little motor. I run mine at 20:1 with r50 or royal purple and 110 octane. It was tough on reeds until i switched to the coated sport jet blocks. I acquired two more this year and am up to five of them now. Just need a few doo dads to complete the last three.

[FMP]

That's a wild motor

[Keaten]

Cool finally some numbers..thanks ok can guy make 250 hp with a fishn mota 2.4 based 2.0 if so wat rpm area does it need to ported for

[Michael J Giesler]

The only problem is no one is making pistons for them good motors on lite boats

[Capt.Insane-o]

Dunno why you would want to go through all that. The 2.0 f1 is a full out race motor, They need a lot of compression, high octane fuel, really good oil, lots of rpm to run. If you have a 2.4 block have James Perry put steel mod vp sleeves in it with some tubes and the other neat little stuff he does. Set it up to run on 135-140 psi. It would take a lot of work to try and make a fishing block 2 liter make an honest 250 hp.

[Keaten]

Ok thats good info im still learning about wats not worth it, and wats realistic thanks ,

[FMP]

The only problem is no one is making pistons for them good motors on lite boats

If you sent Wiseco a piston they could make you a dozen?

[Chaz]

If you sent Wiseco a piston they could make you a dozen?

Sure , just as long as you pay for the other twenty four that it takes to fill a minimum custom order ... :D

[FMP]

Last I asked not too long ago 12, maybe it's a different situation with these but I'm not sure why?

[Chaz]

Askin and writing a check jogs two different memory sensors ... :rolleyes:

[FMP]

100% , dozen was the word. No cheque strictly cash.
Actually I had bought 14 and then asked later to find I could have done a custom. If it's a totally new piston then maybe it's different.

[BUZZIN' DOZEN]

This is going back at least 15 years, but a friend of mine was turning 800cc arctic cat triples into 1108's and he had to order 50 pistons!

[Keaten]

Would it be smarter to replace the 2.0 sleeves with 2.4 sleeves after booring and change pistions to 2.4 of course would that be automatic +25 -50 hp ? ill be porting anyways and running 5or7 petal front with wh20 carbs

[Michael J Giesler]

It was my plan to run a 2.0 champ mod u motor on a lite Allison drag boat just for fun but all of a sudden these motors went from $3500-$5500 to $7000-$8500 for that price it will just be a dream i will stick with my drsgs and my 2006 280/drag dam shame because the old 2.0 liters where good little motors

[Chaz]

This is going back at least 15 years, but a friend of mine was turning 800cc arctic cat triples into 1108's and he had to order 50 pistons!

Yes sir .. and if the "overrun" units that were not blems , you had to pay for them as well . Which still hold's true to this day .

Chaz = thinkin , if someone has never ordered customs .. "WELP"... never mind I have never stuffed thousands worth of Benjamin's in the mailbox and lifted the outgoing red flag .. so what do I know about being assigned a part number of my own .. :thumbsup:

[Capt.Insane-o]

I really like these little motors due to longevity reasons. Next year I'm going to have to bite the wiener and make an order me thinks. Sucks but at least the bores stay round.

[FMP]

Yes sir .. and if the "overrun" units that were not blems , you had to pay for them as well . Which still hold's true to this day .

Chaz = thinkin , if someone has never ordered customs .. "WELP"... never mind I have never stuffed thousands worth of Benjamin's in the mailbox and lifted the outgoing red flag .. so what do I know about being assigned a part number of my own .. :thumbsup:

That's right the man on the phone was clueless and I'm full of snot and like to tell stories, call and ask.

300+ from that 2.0 , that's alright.

[Keaten]

Ok in a perfect world were nothing ever goes wrong or breaks ,if a guy mods a merc 2.0 fishn block with 150 psi heads and 200 psi heads to play with, perfect leak down %s , ground out chest to run 10k ,changed port timing need help in this area for shure !! good pistions top pinned with merc rings, hone holes to match, d or square mod done on pistions with adding a additional hole or holes to pistions, big rods for the rpm i guess? 5 or 7 front with a lot off front much as possible, port reed cages little less than crazy add CCMS reeds 1" intake spacer, wh15 or 20 carbs will start out fat on jetting say 46 idle and 85 mains.. wat would I have then... if done perfect say.. 175 hp lol hope not.. more like 250 at 7-10k ?

[Capt.Insane-o]

The factory 2.0 fish blocks have a big heavy cast iron jug cast in the block, it's not a sleeve like a 2.5. Which makes them more difficult to port. Order an old oval port f1 sleeve from LA sleeve and copy that.

[FMP]

I don't know either teach! Get to the principal's office he said.

[Capt.Insane-o]

Late model pistons. They can be used in older models with new rods.

[Chaz]

That's right the man on the phone was clueless and I'm full of snot and like to tell stories, call and ask.


I have no doubt they know what their doing .
You might have even bought a dozen pistons and a couple spares ... once in your life.
But just as you misquote non applicable text and pictures of a Sea-Do , as having some relevancy to Mercury outboards , I have no doubt you misquoted "the man on the phone" at Wiseco . Which normally should be no big deal . But since it's me ... you would rather stand behind something you have never done nor went thru the beginning stages of having a custom piston built than just say , that you don't know .
Pretty sad , that you would let a guy order sleeves , have a block machined , and then find out that if he in fact needed a custom . It would actually have to go thru engineering and that he would have to sign off on the prints .
And of course , you would need to have an account with banking information on file before they will even consider a custom project . ( they want to get paid for their time )
Like I said there is a minimum order and customs cost more than standard kits . And if you call back the next week ... even for the same part number , you go back to the minimum order . There is no price break unless you order 48 unit all in one shot . Which means it's not cumulative . I do hope that has cleared up some of your confusion on ordering custom pistons .
Cash no chequeinzee ehh ? That I can't say . I'm an American citizen with a clean banking record . A line of credit and references .... and you ???




I don't know either teach! Get to the principal's office he said.


The new year is coming , maybe you need to think about applying a character resolution or two ... just sayin ... :thumbsup:

https://i.imgur.com/K9oTMyGm.jpg

[FMP]

You must be thinking of yourself, you can't hold a candle to me. Friend
And what are you going on about, letting a guy order sleeves???
Why get all spun about what someone said to me about a small custom order regarding easy mods to an existing product line?

[Keaten]

Dwilfong can forward me a example of a port map print to learn from

[90 5.0]

Well I did some brain storming with a new bud of mine and we talked about the 2.0L setup.
I passed my idea of making a thick aluminum sleeve to put in a 2.5 steel sleeve block.
He liked it very much and said he will work up a price to make a set of sleeves for me.
This will be a 2.0L with the same port lay out of a 2.5l but running the small 3,125 pistons.
Now just need to see a top guide Wisco 2.0L piston to see what is what.
I like this because I can do some inside contour work on the .278 thick sleeve.
This way will not have to cut so much out of the out side to get the port I want.
Large on the bottom side and tapers smaller to help with velocity in to the chamber.
Will have to get it plated after all the work is done.
Just a brain storm right now we will see if time and $$$$ will be on my side.

research the merc XR-2, the European race version not the late 80’s bass xr-2.

Its a 2.5 block with an aluminum 2.0 nic plated sleeve. Might help answer some questions on your build

[Capt.Insane-o]

xr2 is steel sleeved. Just a righty sst120/s2000 motor. Still piston ported.

[FMP]

I see what you're saying having the thick sleeves to do your port work but 2.5 vs 2.0 displacement?

[FMP]

You know a rebuttal will be forthcoming from somewhere.

[patchesII]

I see zero reason to build a 2 liter unless you're operating under a rule set that mandates it

[99fxst99]

I see zero reason to build a 2 liter unless you're operating under a rule set that mandates it

Like everything else that is liked or enjoyed on this site is rational and justifiable....just sayin....

[Capt.Insane-o]

I liked the 2 liter on my viper. They are softer on the bottom which didn't upset the boat so bad. Still I could only use maybe 80% of that motors potential.

[FMP]

Really, not much boat for all that motor.

[90 5.0]

xr2 is steel sleeved. Just a righty sst120/s2000 motor. Still piston ported.

Havent looked at one in a really long time, was really thinking they were nic motors. Oh well that’s what they say about memory as you get older.

[90 5.0]

I see zero reason to build a 2 liter unless you're operating under a rule set that mandates it

Some people have tried itnin the past as i recall to take advantage of weight breaks but wasn’t very successful.

I admit it would be a fun build just because but also agree that for any other reason than for fun 2.5+ is the way to go.

[Capt.Insane-o]

*shrug* I've been at this for a little bit. Maybe this year I can show you how it's done. :D

[Capt.Insane-o]

2.5 is a lot cheaper....... Err cost effective to build. Put the right parts in and have it balanced properly.

The two liter worked better in my application, and was much easier on parts. Plus it was fun telling people it's just a two liter. Plus spending less time with the horizon at a 90 degree angle was nice.

[FMP]

312 on a Viper and 2.0 bragging rights. I'm guessing that's crank hp ?

[Capt.Insane-o]

395027

Early piston ported f1 piston

[Krazymaan]

Nothing more fun than watching a 2.0 or 2.4 carbed homemade motor walk away from someones expensive aftermarket bolt together, mapped, laptopped, store bought injected 2.5.

[Capt.Insane-o]

"1000 horsepower" v drives and jet boats are more fun

[Krazymaan]

"1000 horsepower" v drives and jet boats are more fun

No way I'd drive Aladins Magic Carpet with 1000hp strapped to the back of it.

[Capt.Insane-o]

There is some heavy hitting iron over here, but you get those guys out of sight of their trailer and panic attacks ensue. I would leave here drive around the great lakes down the Mississippi to Florida in a heart beat if it was feasible. My attention span is longer than a 1/4 mile :)

[patchesII]

Nothing more fun than watching a 2.0 or 2.4 carbed homemade motor walk away from someones expensive aftermarket bolt together, mapped, laptopped, store bought injected 2.5.

Probably not gonna happen

[Michael J Giesler]

Dam Erik why do have to be so mean you big Bully you it's just a nice little 2.0 liter

[StratosVT]

Probably not gonna happen

That's what I was thinking! Maybe at someones local sandbar where people show up with all kinds of crap but not in the real world.

[Krazymaan]

On the same boat, probably won't happen but with a 2.5 on a heavy boat and a 2.4 on an light boat. It could happen.

[patchesII]

It would have to be at least 200 lbs lighter

[90 5.0]

"1000 horsepower" v drives and jet boats are more fun

I disagree, they are pretty boring to drive.

My xr2001 with a PS motor is more challenging than a heavy hitting car motor on nitrous

[90 5.0]

On the same boat, probably won't happen but with a 2.5 on a heavy boat and a 2.4 on an light boat. It could happen.

Thats why they have weight difference in classes for different cc

[Krazymaan]

I'm just talking about on a lake with friends and goof balls. Nothing too serious.

[Capt.Insane-o]

I disagree, they are pretty boring to drive.

My xr2001 with a PS motor is more challenging than a heavy hitting car motor on nitrous

I meant handing a car motor boat it's ass.

[Capt.Insane-o]

This pic is for Michael 395037

[90 5.0]

It would have to be at least 200 lbs lighter

I think it would take 250 min diff

[90 5.0]

I meant handing a car motor boat it's ass.

oh yeah, that’s even more fun when you are in a bass boat ;)

[Krazymaan]

Getting off track Alert

[FUJIMO]

http://www.screamandfly.com/attachment.php?attachmentid=395037&d=1513742191

[Chaz]

I gotz all ya'all whooped .... Im neckin down a 3.2 Merkury ta 1.7 Litre'z ... !

My wet finger in the air dyno sez 450 HP @ 17,682 RPM ... :rolleyes:

[JrCRXHF]

I gotz all ya'all whooped .... Im neckin down a 3.2 Merkury ta 1.7 Litre'z ... !

My wet finger in the air dyno sez 450 HP @ 17,682 RPM ... :rolleyes:

Chaz must be having some whiskey with his coffee ;)

[Krazymaan]

Chaz must be having some whiskey with his coffee ;)
Nope, you got that backwards he usually has a shot of coffee with his whiskey

[90 5.0]

I gotz all ya'all whooped .... Im neckin down a 3.2 Merkury ta 1.7 Litre'z ... !

My wet finger in the air dyno sez 450 HP @ 17,682 RPM ... :rolleyes:

The way that’s written if you don’t look at the screen name you can imaging mike posting that years back

read it in his voice and it’s even funnier!!


on a serious note , it’s not a bad idea. The 2.0’s are notoriously bullet proof in comparison to some other motors.

Thick cylinders and beat on it at the sand bar. I can get behind that.

[90 5.0]

I'm just talking about on a lake with friends and goof balls. Nothing too serious.

I was completely agreeing, 2.4 on a light boat hurts a 2.5 on a heavy boat. Just using weight breaks in classes as an example.

But the boat the 2.5 is on needs to be significantly heavier.

[patchesII]

Yep, 200-250 lbs

[XstreamVking]

Look at the merc racing motors specs. That's how high you can spin one. And have it last longer than 1 hr.
Here's one going 10500 r's. https://www.youtube.com/watch?v=XZkxJJrB9ZM

[Michael J Giesler]

A good 2.5 pro mod / pro drag aka outlaw motor 11,000-11,500 a little 2.0 mod u motor 11,000-11,500 but the bores will last longer

[Chaz]

Chaz must be having some whiskey with his coffee ;)

Now boss man .... you know I like me a big ol cheeseburger wiff my coffee ... ;)



5.0 :

The way that’s written if you don’t look at the screen name you can imaging mike posting that years back

read it in his voice and it’s even funnier!!

Aye Bouy , I jus tri-inn to feet een wit de nu loat of tech czar'z aye ... :iagree:

[patchesII]

Giesler nailed it. I don't think the 2 liter will turn any more rpm than the 2.5. Certainly not enough to overcome the difference in torque

[90 5.0]

So let me ask why you all think a 2.0 will not rev higher?

It’s the same crank throw with a smaller piston, generally speaking when comparing motors in other aspects the motor with the shorter crank throw spins higher.

If you took a 2.5, and destroked it to 2.0, vs sleeving it down I then could see higher rpm.

But thays just speculation.

[90 5.0]

A good 2.5 pro mod / pro drag aka outlaw motor 11,000-11,500 a little 2.0 mod u motor 11,000-11,500 but the bores will last longer

I’ve heard stories of some old roundy round guys getting the 2.0 race motors up around 13k, but I’ve never seen it.

So I say it’s “possible” but they might just be shop stories, you know how that is.

A better question is why wont a 2.4 turn over about 8500, but I’m sure porting isnthebanswer there

[Chaz]

It’s the same crank throw with a smaller piston, generally speaking when comparing motors in other aspects the motor with the shorter crank throw spins higher.

If you took a 2.5, and destroked it to 2.0, vs sleeving it down I then could see higher rpm.

But thays just speculation.

As accurate as that is , I would file that under "basic engineering principals" instead of speculation .. :thumbsup:

Although I have found that the best alternative to more displacement is to "add" cubic inch's ... ;) It's nice to see that two years later that my ideas on the importance of transfer port layout are starting to sink in .... :eek: :D

https://tse3.mm.bing.net/th?id=OIP.fjqdoiWspaSJF00dhQx-RQEsES&pid=Api&P=0&w=176&h=162

[powerabout]

smaller bores in an outboard allow larger ports in the block, I wonder if that makes a difference?

[Capt.Insane-o]

rpm..... used to be this kid in my neighborhood that had a nice 10-12 speed whatever bike. Always saw him in 1st 2nd or 3rd peddling at the speed of light trying to keep up with everyone else. :confused:

[JrCRXHF]

piston speed and the forces that go with it limit a lot of motors in terms of short blocks and rotating assemblies.

[Capt.Insane-o]

Ignition component saturation comes into play too,

[90 5.0]

piston speed and the forces that go with it limit a lot of motors in terms of short blocks and rotating assemblies.

What I like to call “the rod limiter”

motor blows up, asked
“how high did you spin it?”
”All the way to the rod limiter”

[patchesII]

A 2.5 will turn more rpm than I want to. I've seen more than one turn 11500+ and more than I can count turn over 11000. Many that are turning those rpm's are trying to get the r's down. A million rpm doesn't necessarily mean it's the quickest way down the track. I'll give you another tip, with good components these things will turn 10500 and last virtually forever, get over 10800-10900 and it's a time bomb

[Krazymaan]

Fong, when are you gonna sneak your boat out and shoot it across Lake Tohopekaliga

[XstreamVking]

Saw a formula sheet and curve chart at merc school that had the numbers for the forces applied to moving parts (piston stopping and starting) and how it increased with rpm's. The numbers were astounding.

[FMP]

Or lighter big bore than stock doesn't hurt

[Krazymaan]

248 grams

[patchesII]

500 gram piston is stock weight. They can get lighter. If you look hard enough you can find lighter pins too. Could always go to 141 rods. I've had them as light as 327 grams

[FORBESAUTO]

Lol, no he has had the 141 rods at 327g :thumbsup:

[patchesII]

141 rods that were 327. I run stock weight pistons, light pins and Verdi rods

[patchesII]

I've had several sets. They're usually mid 380's.

I don't know how familiar you are with my setup or the class I run but I don't turn a million rpm. I'm much more concerned with the pistons living through massive cylinder pressure than I
am with revs

[RBT]

I've had several sets. They're usually mid 380's.

I don't know how familiar you are with my setup or the class I run but I don't turn a million rpm. I'm much more concerned with the pistons living through massive cylinder pressure than I
am with revs
Lol, as per your previous comments those of us that see our telemetry and see a real 11k plus kinda think shi!t it turned up again need to back that off.

[Chaz]

I don't know how familiar you are with my setup or the class I run but I don't turn a million rpm.

If he did , he'd already know that the "real" blocks come with wings in the ports .. ;)

https://i.imgur.com/Q2MnTUal.jpg


I'm much more concerned with the pistons living through massive cylinder pressure than I
am with revs

He's still years away from sailin a head two rows deep into the spectators ... Best way to learn is to have the ol boy come up and buy into the Calcutta while he still knows everything ... :D

https://i.imgur.com/cnEujqal.jpg

[RogerH]

2.0L Chrome Bore w/FI:
Back on Pg 4, Post #50, dwilfong questioned if there was a 2.0 chrome bore block
Well, I think I just inherited one with a Paul Heathman Tunnel Hull project. It came with a 2.4 "fishing" mtr and this 2.0L power-head.
Will build the 2.4 first, but want to also build the 2.0L when time and $$$ allow. First I'd like to know what I have!!!!!

The 2.0L S/N location is stamped: SHOW ENG .....I also found that the manual up/down Mid S/N plate is also stamped SHOW ENG
Yup!, the motor has no guts (pistons - rods) but does have a crank so the motor could be complete outwardly. It has some quirks: 1) no light flywheel, 2) does have the LH starter, 3) had one NOS 2.0 head and one 2.4 used head, 4) EVERYTHING but the one head is NOS! It is dirty from years of storage + the rig was used as a display boat by the Miller American race team (The boat was bolted to the trailer - not any more!).
Take a look at these pictures and tell me what I've got please. I think it represents a Champ 2.0L motor of its time period.

395305

395306

395307

395308

395309

395310

395311

[Capt.Insane-o]

Yessir, here is one of the pistons I have for you

http://www.screamandfly.com/attachment.php?attachmentid=395027&d=1513724279

[Capt.Insane-o]

How much dose that piston weigh??????????

Hell if I know. Batteries are dead in my scale.

[JAFFA]

Phase 1, 2ltr F1?
Like the finger ports

[wrechin2]

Dunno why you would want to go through all that. The 2.0 f1 is a full out race motor, They need a lot of compression, high octane fuel, really good oil, lots of rpm to run. If you have a 2.4 block have James Perry put steel mod vp sleeves in it with some tubes and the other neat little stuff he does. Set it up to run on 135-140 psi. It would take a lot of work to try and make a fishing block 2 liter make an honest 250 hp.

I agree and thanks! It can be done but would not be worth the cost. I just wrote the program for some experimental sleeves and just got through cutting a set for a XR4 I am building for the race team that I sponsor in COR racing. I am trying some stuff using what I have learned from 260's and 300 drags as bigger is not always better. I have a true 2.4 mod VP that I have built and this one and will see if the new sleeves are bettor or worse. I would really suggest using a fat block 2.4 to get those kind of numbers with the "behind the liner" tubes that I do with some of the new sleeves (if they work!).

[wrechin2]

Probably not gonna happen

T-rex used to hurt a lot of 2.5L feelings with a 2L...just saying

[Keaten]

Thanks for all the great info I didn't know this thread was Goin turn into all this ... I love learning as much as I can..

[wrechin2]

A better question is why wont a 2.4 turn over about 8500, but I’m sure porting isnthebanswer there

Porting is probably the answer. I am working on that! I have tried many port maps on 2.5's and finding out some very interesting facts on port shapes and sizes effect the engines rpm range. I done 2 engines when I first started making sleeves and used a 2.5 200 program and raised the roof of the ports to 260 specs and left the lower portion in the same place which made for very large transfers, booster and finger ports. Both engines done good up to 6500. 1 struggled to pull 7k and the other wouldn't go past 6500. They would have turned more if a small prop were used. I then wrote a new program using the same port timing (roof) but changed the shape/sizes (everything else) of my ports. Look at how small the transfer ports are in a STOCK 260 and 300 drag. They are smaller that a 200 fishing engine that isn't meant to turn high rpms. I redone both engines and the one that struggled to pull 7K now has 2 hours on the new sleeves and the first time he stabbed it for a short burst, it turned 7800 and hit 100 mph and was still pulling when he let off. He stated there is a night and day difference all around in performance. Amazing from simply going to smaller ports. The other one is sitting on a stand. The 2.4 has very large transfer ports like the sleeves I initially done for these 2 2.5L and honestly it is probably larger. I am trying the new shape/size so we can take advantage of a 100 lb weight break in a class in the Parka Enduro running a 2.4 instead of the 2.5.

To better understand. Take a deep breath and hold your mouth wide open and place your hand 6" in front of your mouth. Expel hard and feel the velocity you produce. Now do the same thing holding your mouth like you are whistling. Feel the difference? You didn't produce any more pressure you just used it better. The crankcase pressure remains the same as well in the engine. The large ports don't have the velocity the small ports do and can't transfer the fuel fast enough at higher rpms which limits it capabilities. Also the exhaust flowing out of the block creates a siphoning effect and aids in drawing the fuel in and the smaller ports also act like a venturi in a carburetor and speeds up the charge in. These are just my thoughts and experiences on the subject and only testing will tell me if I am in left field on this.


STOCK 2.4 150 XR4 sleeve and My new sleeve. See the difference in the transfer port.....open mouth versus whistling.....

http://i68.tinypic.com/25sndz7.jpg

[90 5.0]

Porting is probably the answer. I am working on that! I have tried many port maps on 2.5's and finding out some very interesting facts on port shapes and sizes effect the engines rpm range. I done 2 engines when I first started making sleeves and used a 2.5 200 program and raised the roof of the ports to 260 specs and left the lower portion in the same place which made for very large transfers, booster and finger ports. Both engines done good up to 6500. 1 struggled to pull 7k and the other wouldn't go past 6500. They would have turned more if a small prop were used. I then wrote a new program using the same port timing (roof) but changed the shape/sizes (everything else) of my ports. Look at how small the transfer ports are in a STOCK 260 and 300 drag. They are smaller that a 200 fishing engine that isn't meant to turn high rpms. I redone both engines and the one that struggled to pull 7K now has 2 hours on the new sleeves and the first time he stabbed it for a short burst, it turned 7800 and hit 100 mph and was still pulling when he let off. He stated there is a night and day difference all around in performance. Amazing from simply going to smaller ports. The other one is sitting on a stand. The 2.4 has very large transfer ports like the sleeves I initially done for these 2 2.5L and honestly it is probably larger. I am trying the new shape/size so we can take advantage of a 100 lb weight break in a class in the Parka Enduro running a 2.4 instead of the 2.5.

To better understand. Take a deep breath and hold your mouth wide open and place your hand 6" in front of your mouth. Expel hard and feel the velocity you produce. Now do the same thing holding your mouth like you are whistling. Feel the difference? You didn't produce any more pressure you just used it better. The crankcase pressure remains the same as well in the engine. The large ports don't have the velocity the small ports do and can't transfer the fuel fast enough at higher rpms which limits it capabilities. Also the exhaust flowing out of the block creates a siphoning effect and aids in drawing the fuel in and the smaller ports also act like a venturi in a carburetor and speeds up the charge in. These are just my thoughts and experiences on the subject and only testing will tell me if I am in left field on this.


STOCK 2.4 150 XR4 sleeve and My new sleeve. See the difference in the transfer port.....open mouth versus whistling.....

http://i68.tinypic.com/25sndz7.jpg


Good luck with that and sounds like you are on the right track, in small ci car race motors we did some similar testing on porting(302-310ci ) and found that closing down some of the port map intake side and opening on exhaust roof but not floor worked a lot better than the port maps from our 351-400ci engines

i tried the same thing last season because my boat was light and the 100lb weight break meant I didn’t need to add a ton of weight in the boat like I would have with a 2.5.

Came out of the hole hard but got drug on the big end every time. But these were stock ported engines.

Also mainly did it because I didn’t have a legal 2.5 yet, will try it again in the beginning of the season but we have a 2.5 getting priced together also.

When the 2.4’s were competitive they had a 150lb weight break.

I’d be very interested to see how it comes together for y’all.

[wrechin2]

It will be interesting as I am comparing it to a known performance engine with the Mod VP which isn't stock because I made the chest look like a 260 block and opened the exit. I have found this improves a lot but can hinder if gone overboard. I do this to my 2L we run in COR as well which helps flow. I would hate to do all this completely by hand! #6 port has to be done by hand as it is under the bridge. A lot of stuff that would need to be done to make this 2L a screamer would take a lot of time.

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