3.6 GT powerhead details

[Hillclimber]

Hello

I am the mad "Hillclimber" from England building a race car using a V8 two stroke with CVT transmission.

I have just purchased two 1986 3.6 GT powerheads from a fellow in Las Vegas and these arrive in the UK in October, Type E300CXCUR. I assume the C is counter rotation i.e. anticlockwise looking at the flywheel ? I will build one engine from the two, serial numbers are consecutive. Initially in standard form and when all running OK modify other block for expansion chambers, reporting etc.

I have spent many hours searching the S & F Forums for technical details of these engines BUT cannot find the details I need to select the correct CVT and other components.

What I need are:

A power - torque -rpm curve for the standard engine

The port opening/closing times and/or degrees on crankshaft, and the open areas of the ports

A power - torque - rpm for a modified engine with about 400+ hp

Has anyone manufactured successful expansion chambers for this engine? If so dimensions appreciated.

Has anyone experience of running the engine with horizontal crankshaft i.e. lubrication problems with bearings?

I am one set of carbs missing - Any for sale

Where is best supplier of spare parts and/or race components?

Any help - guidance of where to get the information appreciated. BRP/Merc/Invinrude not helpful on my questions.

Peter

[powerabout]

How will carbs work when the engine lays down?

[PanRonnie]

i don,t want to rain on your parade but i can save you a lot of time and money
you will not be satified with the result off suchs a conversion
3 years ago i was contacted by somebody from england who had build a mercury 2.5 on his drag bike and installed a DTA S80 ecu
i helped him get the thing running but he never showed up in any drag racing pictures

a 2 liter engine https://www.youtube.com/watch?v=22kPfqRmShI
but if i were i would install one off the aluminum crate engines
http://www.chevrolet.com/performance/crate-engines/ls3.html
or you can ask him :)
https://www.youtube.com/watch?v=mrhsUXnodfw

[powerabout]

Boosted 4 strokes how about NA engines that are 100hp/ltr which is easy for an outboard.

[Hillclimber]

If I cant cut and turn 90 degrees, then I will use 8 Mikunis

[Hillclimber]

351938Here is a Hillclimb car built in Spain, won the championship, then 2 strokes were banned next year! Its a 400hp two stroke or nothing. The attached thumbnail shows carbs which can turn 90 degrees.

[Hillclimber]

I think this could be him - John Finch?
351939

[STV_Keith]

Maybe Racer (Al Stoker) will chime in as he was an OMC guru and had a dyno. I have dyno charts of my Monty Racing built motors, but knowing what Monty did to them, I doubt the curve is the same. Find my thread in the Outboards for sale section. Pretty sure I posted a dyno chart in there.

[powerabout]

which way will the crank be in your car?

[atclen]

Here you go !


https://youtu.be/RoiWpJLokEc


https://youtu.be/mrhsUXnodfw

Anything can be done if you got time and money !!

[Hillclimber]

Horizontal crank probably with carbs/EFI at the side.

[powerabout]

ok so lay on side with one head high and then rotate carbs 90 degree?
Just go EFI, build a plate to hold the reeds and injectors with a flange to hold a plenum ( or put injectors here) with a few throttle bodies in it
Hopefully Racer chimes in about top bearing lubrication?

[racer]

Peak output on a stock 3.6 powerhead was generally right around 6200 with a couple I saw 6500, how well the intake ports were matched made the difference. The exhaust has enough height to make peak at 7500 but does benefit from some added width. To make 400 without pipes it will need a fair amount of work including fingerports.

A horizontal engine will need to keep the mains oiled as normally the oil falls down the crank and is pumped back up to the top main with a one way valve in the line. Drag engines the upper lasted better with main being oiled good prior to starting. I would want to see some angle with the lower main below the upper so oil will make it down in order to be pumped back up, this is how we use to run a V4 in a midget race car.

Keith was? memory is not what it use to be. Torque curve does not move much below 5500 unless a lot of compression and/or really big ports.

When I can get to dyno records that I still have will post a few numbers, most went with the dyno when I sold it to Sea Way so they had good starting points as they learned the dyno.

[powerabout]

Here was/is a way to add EFI as a bolt on ( Taylor Marine) but you can also get other companies that put an injector in a throttle body ( in the UK)
The 2 piece inlet is an Al Stoker ( Racer) showing that if you build something to hold the reeds then you are free with the inlet.
One of my buddies in OZ milled a stock inlet down to that level then made a custom front to hold the carbs.

[Hillclimber]

Hi Powerboat
Thanks for the pictures etc. Do you know if anyone has tried 8 or 16 injectors directly into the transfer ports avoiding the need of reeds? probably with a supercharger to boost/correct/control the fuel - air mixture? I am only "Thinking" at present since I do not have an engine in front of me to see whats possible/feasible with the ports. On one of my two stoke projects I added extra external transfer ports which dramatically improved power - torque output. I may have to consider an oil pump delivering oil directly to all bearings plus cylinder spray, all monitored by 8 EGT and/or air/fuel sensors, rather than a 25-50 to 1 premix. Smoke generation using premix is one of my problems as is noise generation.
In my type of motor racing, I only run between 1 to 2 minutes at maximum power, so the supercharger can be driven by a compressed air supply avoiding any parasitic loss of power from the engine. I will also fit an electric water pump. Now I am onto calculating the surface area of the radiators I need to fit. What is the optimum working temperature of the engine? Lots of questions before I start the project.

[Markus]

Start by contacting stenmark on this board. He built the Volvo Rudezon in the clip above.

[racer]

Operating temp best power without cold seizure is at 105 degrees F. Best for safety without giving up too much power is at 130F after 145F they start to loose top end power. I did a reed test a couple years ago that shows the power loss at higher temp.

[powerabout]

is that block surface or exit water temp?
How does the temp vary from top to bottom of block and a head?
Is there a hot cylinder and is that a fuel or cooling issue? Same 3.6 and 4.0?

[Hillclimber]

I know this is a boat site but thought you would like to see the car the V8 is going in - its a Lynx3000 previously raced in Sports car racing.352815

It weighs about 550kg (1200 lbs.)

[powerabout]

what engine would it normally have and how heavy is it?

[racer]

Cambell that is exit water temp but when everything is right block temp is 5 degrees warmer. With work you can get them to maintain very similar block temp from the bottom to the top, its not as uneven as the 6 to start. 3.6 tend to have warmer internal temp on 2 and 4 while the 4.0 is 3 and 5 which I believe to be in the slight exhaust tuning difference between them.

[Hillclimber]

These would typically have a Ford Cosworth V6 - 24V with about 270hp and 200+ lbs/ft torque and weighed in about 350lbs (160kg) without gearbox.

[racer]

Sounds like your project will be lighter with a lot more power.

[Hillclimber]

Hi Racer,
Yep thats my plan. In England we have many competitive Hill-climbs which are often private roads from the 1900's which originally/still connect the big Country houses/mansions to the public roads, often over 1 mile long and always going uphill to the local high point where these properties were built. These are now used, probably twice a year, to hold organised Hillclimbs where 120+ competitors will compete in different class's and its a timed run against the clock. At the end of the day, the "Top 10" (i.e. the fastest competitors) have a run off to claim FTD (fastest time of the day). This is currently 4-stoke dominated, so I have set myself the task of getting a two stoke into a "Top 10" runoff before I am called to the Hill-climb in the heavens - I am 72 years young!
Here is a link to Shelsley Walsh - the oldest competitive motorsport venue in the world where my best time is 33.03 seconds in a 600cc Rotax two stroke powered USA built f500 car. http://www.shelsley-walsh.co.uk/. I am competing there at the September meeting driving a Marcos Sports car with a V6 220hp 4 stroke.

[Hillclimber]

The two power heads are en route to me in the UK so time to consider what I need to resolve. Both engines are counter rotation and I probably need to run reverse rotation. I will have a new flywheel without magnets etc. (converting to CDI system with signal from crank sensor) - is there anything else I need to change to allow it to run "backwards" ?
The power head will be installed with a horizontal crankshaft. "Racer" has warned to instal crank with slope to rear, allowing oil to run down the crankshaft to a valve/pump which transfers the oil back to the top of the crankshaft ensuring main bearing lubrication. Can anyone identify this "Pump" on a parts list as I cant find it.
Anyone fitted an external oil reservoir +pump to independently spray a measured quantity of oil directly to the mains/big ends? The old Scott two stroke motorcycle used this system of remote oiling complete with a glass inspection tube and control valve to regulate the oil flow visually!!.
I am currently exploring the "Science" of fitting 8 expansion chambers - if anyone knows of someone who has successfully done this (I gather they are banned in the USA) then please advise contact details.

Peter

[STV_Keith]

In my experience, expansion chambers will increase the power/torque in one area, but take it from another area to do so. Not such a big deal with a lightweight dirtbike or similar, but when you need a broad torque curve, you're likely better with something similar to the stock tuner, which flattens and broadens the power delivery.

[powerabout]

pipes on a v8
https://www.youtube.com/watch?v=RoiWpJLokE
(https://www.youtube.com/watch?v=RoiWpJLokEc)

[frank jackson]

The pump you are asking about is not a pump .. The motor crank rotates in the bottom of the block and creates a pulse the positive pulse is pushed up the line to a check valve . Some models add more from the idle recirculation vales and goes up to the top bearing . There is a hole that goes to the intake from the crankcase where the top bearing is . This gives a vacuum to help draw the oil up the hose ....In your application I would put a oil bottle and gravity feed all the main bearings . You will need to drill the block and run your own passages .... just my 2 cents

[powerabout]

it also depends on what part of the block you intend lay down, exhaust or inlet?

[Hillclimber]

Hi STV

Thats why I have finally selected to use a CVT transmission. This allows the 2 stroke to operate at a constant predetermined RPM matching the highest max hp and torque figures. By changing various springs, cams etc. you can "Tune" the CVT plus the point where the belt engages and drives. I anticipate this to be about 4000rpm and 0 to 60mph will quicker than a F1 car off the grid.

[Hillclimber]

Hi Frank

Thanks for the info. To my knowledge there are none of these V8's in England, hence no knowledge so I am on a big learning curve

[Hillclimber]

To prove the concept of my project, I will initially run with 8 carbs with float chambers so these (the inlet) will be horizontal. If successful, I then upgrade to EFI, CDI, and the 8 expansion chambers.

[powerabout]

To prove the concept of my project, I will initially run with 8 carbs with float chambers so these (the inlet) will be horizontal. If successful, I then upgrade to EFI, CDI, and the 8 expansion chambers.
Do you mean standing up the engine like it was as an outboard or making 90 degree adapter for the carbs and laying the engine on it back/exhaust?

[Hillclimber]

Sorry, I mean with the crankshaft horizontal and putting on 8 separate carbs. Its a mid engined car so exhaust may run through the car and exit on passenger side. Lots of things to consider.

[powerabout]

did you have in mind to use the original carbs with adapters?
Perhaps lay the engine on one side so your inlet is horizontal might be easier?
Working out a coolant flow will be another challenge depending on how you mount it?

[Hillclimber]

Yes engine will be on one side. I am waiting for arrival of engines from USA but I think I can cut the 4 dual carbs to make 8 independents each with a float chamber. Otherwise I will use 8 Mikuni as used on the Rotax engines.( I have lots of jets for them). With 8 you can tune each carb to cylinder requirements at circa 6800rpm (my CVT operational RPM) and hopefully avoid piston seizures.
Currently I am having to consider a tank of iced water on board plus radiators + fans to get to the operational temperatures suggested/recommended by Racer. I am also considering CO2 injection into the coolant as its much less weight than racing with a tank of iced water!
ANY thoughts/ideas on these problems, by anyone, appreciated since I am in complete new territory. and I love a challenge.

[powerabout]

I'd say electric pump(s) and radiators would end up being the easiest at the end of the day.
The carbs are individual its the throttle blades that are grouped into 4 lots of 2.
You might want to set up a bench to run the engine to ensure it runs properly before you do anything else.
Then lay it down in the workshop to get it to run after you alter the carbs.
www.epc.brp.com

(http://www.epc.brp.com)

[Hillclimber]

Great for the help/advice !!
Just looked at the BRP parts list (thanks) and can see the throttle blade arrangement. Looks like a problem I can solve.
Electric pumps definite, I am taking no parasitic loss's from the engine. My calculations at the end of the full development programme is 525hp and a top ten placing at top England Hill Climb - Shelsley Walsh. Job done in 2019 when I will be 75yo and can retire gracefully.

[powerabout]

here is some horsepower from a V8, I would hazard a guess that the only factory part is the crank?
http://www.screamandfly.com/showthread.php?276838-Outboard-World-Record/page4&highlight=monty+efi

[PanRonnie]

you should use a mercury instead of an evinrude :cheers:
http://mercuryracing.com/mercury-racing-reveals-sb4-7-0-automotive-crate-engine/

[Hillclimber]

No - I only race two strokes!

[rude tim]

The engine has 8 single carbs from the factory.

[frank jackson]

you will most likely find the mikuni carbs easyer to deal with . The brp jets are getting harder to get and expensive ....jmo..

[Hillclimber]

All of my research and current deliberations of how to make the most out of the OMC 3.6GT powerhead indicate that one needs to increase RPM to get extra/increased power. My calculations indicate that the "Standard wide rings" are going to be travelling at their safe limit of 40,000 Ft/sec2 at 7000 RPM. What happens at 8 or 8500 RPM?

Previously, to increase RPM on other engines, I have converted to "Dykes" rings (L shaped - very thin - fitted close to piston crown - and OK for 100,000 ft/sec2) but the standard OMC pistons do not allow space for this modification.

My calculations of the 3.6GT with EFI + 8 separate expansion chambers + CDI conclude that 8750 RPM is where I need to be aiming and obtaining about 500 HP.

I.E. - The existing design pistons will fail.

So does anyone know if 3.6L pistons are available un-machined allowing Dykes rings to be fitted or is there an "After Market" supplier of Dykes ringed pistons?

ANY comments or advice appreciated.

Peter

[STV_Keith]

Might be time to contact Monty Racing and ask Gordon. He's got lots of these things out there, and in race trim, they turn waaaaay over 8750rpm.

[racer]

I have and I know other have run these engine over 9k. Problem is not the rings it is the standard pistons are cast. To run reliably above 7500 you will need to run forged like the ones wiseco makes for them. These pistons don't use a dykes ring but do run a ring that will easily take the rpm you mentioned. You can get 500 HP without expansion chambers. Since you will need pistons I would bore them to 4.0

[Hillclimber]

Hi Racer

OK I will go for 500hp + without expansion chambers BUT I cant see how. No doubt you have explained this all previously but I cannot find the thread - any guidance appreciated.

[stenmark]

Just my 2c.. skip the carbs.. Build a plenum and run a system like the VEMS efi witch can handle both injection and timing sequentially.
Sure helped me alot.

/Rudezon

[powerabout]

Just my 2c.. skip the carbs.. Build a plenum and run a system like the VEMS efi witch can handle both injection and timing sequentially.
Sure helped me alot.

/Rudezon
Where did you put the injectors in your V8 in relation to the reeds, before or after?

[Hillclimber]

Happy New Year to you all - I have been busy in the workshop during the holiday period. I am very pleased to say that both of the V8's are fully stripped out and look to be in excellent condition internally. I could not measure any wear on the main, big end, or other bearing surfaces and these are 1986 engines.
I did find one problem. Four of the six main bearings I took out had cracks in the outer bearing ring - see photo. These cracked pieces had broken away from the ring, rubbed on the crankshaft, got hot, and are now very blue.
Is this a normal problem? Which are the best replacement bearings and where to purchase?
Does anyone have a drawing of the exact passage of cooling water through the block? I am considering cutting away the cast Exhaust "Ducts" but can see various 1/4" holes drilled to allow air to escape from the No. 1 and 5 cylinder jackets into this exhaust jacket.364403

[PanRonnie]

Something like this

[Hillclimber]

Hello PanRonnie
Yes that is the drawing I have BUT it does not show all of the waterways. There are two passages which are on the inner surface of the exhaust manifold where the V8 figures are cast in, and where do they go/come from - is this the supply for the cylinder cooling?

[powerabout]

The drawing sort of shows the water coming up the aft exhaust dump but its coming up the 2 aft ports into the water jacket over the exhaust

[PanRonnie]

bit unclear off what we are talking about :nonod:
so lets clear it a bit with pictures :rolleyes:
BLUE cold water coming up around the exhaust to the top
RED drain from the heads down into the mid sections
when they drew the v8 it was probably friday afternoon so a bit unclear :leaving:

[powerabout]

Thats a v6 Pan but yes similar with water at the back to cool the water jacket

[PanRonnie]

meaning?

[powerabout]

Hillclimber hasnt got the mid hence his questions because of the drawing.

[PanRonnie]

well to put it
i think coming up around the exhaust down between the cylinders
up near the orange arrows into and around the cylinders to the top
into water thermo stat down the cylinder heads back in the block through the passage ways
to the small channels on the side where it exits into the mid section
but a picture from the V8 itself would be a lot better :confused:

[powerabout]

meaning?

They are a bit hard to follow I have to admit if you didnt actually know them as the in water flow in the powerhead doesnt match the adapter as it moves across the adapter.
The exhaust fills from the middle as well ( also allows it to drain when tilted)
These 2 v4 photos show it a bit better I think ( v6 v8 are also different)
(Adapter photo belongs to 6killer I think)

[powerabout]

v8 adapter

[Hillclimber]

Hi

Here is a picture of the exhaust end of my V8.

The two ports I am trying to identify, not on the OMC drawing(s), are opposite the 2" figure on the rule at the outside of the exhaust manifold. These ports end about half way along the exhaust casting and the only water connection I can locate are 4 x 1/4" holes that are drilled allowing water to enter (or return) these ports from the cylinder cavity. Any ideas?364648

[Hillclimber]

My next area of research is how to achieve the correct water temperature (as per "Racer's advice) for engine cooling.
Does anybody know the pumping rate (US Gal/min) of the V8 water pump, at what pressure, at what RPM?
I am looking at small radiators with CO2 "Spray" to get down to the required lowish temperature in a 90F environment. The CO2 is injected in front of the rad and controlled by temperature activated solenoid valve.

[FUJIMO]

http://www.screamandfly.com/attachment.php?attachmentid=364406&d=1484080134

[FUJIMO]

http://www.screamandfly.com/attachment.php?attachmentid=364648&d=1484329682

[FUJIMO]

http://www.screamandfly.com/attachment.php?attachmentid=364631&d=1484310157

[FUJIMO]

http://www.screamandfly.com/attachment.php?attachmentid=351937&d=1470761211

[racer]

Rectangle at tape measure is exhaust as are the 2 squares right in front of tape, everything else is water intake except the 2 holes about 1/2 inch by 1.5 which are water exit.

[Hillclimber]

Some time since I posted but project now gathering momentum. Just got the 8 new Mikuni carbs(no float chambers) which fit well onto the original throttle bodies. I am removing the butterflies from the Mikunis as connecting 8 of them together into a single operating lever is/was a difficult task. Spare engine shell + CVT now located in the car, fitted perfectly. Also solved the problem of getting oil to the five main crank bearings(horizontal crank location) by drilling 3/16" holes to connect the original priming ports to the bearing housings. Then using a Rotax oil injection pump to supply the oil at pressure to a 5 outlet manifold. Oil flow can be adjusted. I now have the 4" adapter plate which has helped sort out the cooling water flows & returns. I am now replacing the flywheel(incl. CDI) with the CVT primary pulley. Whilst I am still looking at the Megasquirt to control the new ignition system, can anyone recommend a suitable, ignition only, engine management system + new coils etc.380769380770

[powerabout]

https://electromotive.com/product-category/xdi-ignition-systems-restricted/
(https://electromotive.com/product-category/xdi-ignition-systems-restricted/)
used here
ww. boat racing facts. com/forums/showthread.php?6393-Mercury-Mark-40-H&p=136141&highlight=ignition#post136141

you need to go from idle to max advance the instant you kit the throttle hence still going mechanical advance ( like it was) is the simplest way and also to control idle speed.
PS you will need 2 of them to cover 8 cyl

[Hillclimber]

The V8 is now fully assembled and installed in the car. I finally built my own ignition system using a M & W CDI ECU which takes my 8 Hall sensor signals and via 8 new coils gives me a 44,000 V spark. I made a manually rotating disc for the Hall sensors which can rotate between the 4 and 16 degree BTDC positions.
I also found a very small medical pump to supply oil to the 5 main bearings. Volume pumped varies with voltage to motor from 2 to 6V. I made the system to operate the 8 Mikuni carbs from a single cable pull - similar to the OMC system. Startup looks to be mid April. 1st race is in June.
402762

[Hillclimber]

Project has been delayed, only waiting to finish a new flywheel and ready to run. My new ignition system tested and runs OK as does the oiling system for the crank bearings.

Surprisingly I have 3 requests to supply the ignition "kit of parts" - the circular disc which holds the 8 Hall sensors (it rotates from 4 to 16 degree BTDC), the 8 sensors plus magnet - 8 ignition coils for 44,000v spark, the ignition module which takes the Hall sensor signal and sends medium voltage signals to the coils. The module is partially pre-wired.

Cost: US$3600 delivered USA excluding any import tax's.

Some details on attached photo413651413652

[rude tim]

You will need to adapt some kind of bearing support for the other side of the drive. I do not think that the crank will withstand that type of load! The upper main bearing is designed to withstand the two rods and a flywheel only (no pulling at a 90 degree from the main). I believe that that drive will cause crank shaft deflection and take out your rod bearing and break the crank. Looking at the picture above may be if you have the room to move the drive to a seperate shaft with two bearings driven by a spline off the crank?

[Hillclimber]

Yep all planned - here is the secondary pulley arrangement. To race, I have to pass a static noise test. No pass, no race. So I have used the original splined drive shaft - shifter dog clutch. Shaft diameter is ground by 50 thou to fit the CVT pulley, 1/4" keyway cut in, and I made the "Female" dog clutch inside the adapter which bolts directly onto the differential flange with a bronze support bearing inside. The shaft at the non drive end will be supported in bearings, The Primary CVT pulley on the end of the crank likewise, plus a link between the two shafts to set the 11 1/2" required for correct belt tension. The dog clutch will be operated by a "Lever" from the driver seat.413699

[HaulNbass]

Would a service manual help you any?

[H2OPERF]

I put direct oil to each of the mains on the v6 im building , i used an optimax oil pump ,they are 12v solenoid type with 7 tiny pistons that send out about a droplet of oil evenly to a 3/16 hose with each pulse. Not sure how your going to distribute the oil but these are readily avail used on ebay fairly cheap. Dave

[Hillclimber]

Pleased to say the car had it first race last weekend, at least it finished. I now have a 30 point snagging list to complete over winter before next season. With the crankshaft horizontal the exhaust exits through the "Passenger area" with a rectangular pipe and silencer(muffler) I made including a copy of the megaphone. This has created too much back pressure at WOT and the smoke does not escape correctly. I am now going to fit the original inner exhaust housing plus original megaphone.
QUESTION: When a V8 is on a boat with exhaust under water, what is the pressure at the exhaust outlet?
I am considering fitting one big or two small Turbos to use their natural ability to reduce noise level. The generated air would be used to cool the inner exhaust, not (yet) to increase engine power.
Any help/advice appreciated. I have to get down to 105db noise level before I can race.449991