Building a 348 Le Mans Race car for the road

I did not see the piston squirters, but did see an allen screw where the squirters are supposed to be installed.

 

That is some GREAT stuff Sy!

It looks as though they modified the head to use 33mm valves, and the reliefs in those pistons are DEEP? Guess you have to have that much clearance with the size lobes that thing is running. Wondering if you could put a micrometer on those and give us the specs? Also how about the front cover for the oil pump chain? Did that just mount up normally, or does it look modified?

 

Awesome pics Sy!

 

Your engine looks wonderfull, I´ll hope that you could use it on the street later.

Check this webpage, it´s from a Japanese engine specialist, maybe their headgasket could fit in your engine F129B.
http://www.todaracingusa.com/F355_usa.pdf

Please keep posting, I´m learning a lot with this thread.
Regards.

 

Very nice workmanship!

Don't waste your time looking for gaskets... that setup is extremely nice and very reliable. Cooper's rings with Orings, hails from the F1 and CanAm racing days. Exactly how the F50 is put together.... hell, maybe the same parts were used. If not I have some super secret sources I can share with you. You would have a dickens of a time having gaskets seal up with the rings in place regardless. I would suggest some very accurate CR tests at this point as you HAVE to know this for fuel specing and engine management programing. No better time than now and those combustion chambers look pretty shallow. No head gaskets and shallow chambers... could be approaching 14:1... you need to know this or the knock sensors will be activated constantly at idle.

Re think some of this. You have to remember, its a race engine which amounts to the ultimate compromise. It was planned to be torn down / rebuilt every 10 hours Max. The tensioner is made from the early style that had a tendency to fail (in its original form) and wear out quickly (darker brown plastic). It didnt matter on an engine coming apart again soon, the chain wouldnt stretch that much between builds. For your uses it is easily justified, quite cheap and very reliable to put in the latest OEM style. Oil Cooling Jets were likely eliminated as that would throw the extra weight of oil on the pistons that wouldnt be required for an engine with a limited life design, they had shelves full of pistons and liners for a pro LM effort.... for your uses they would be an asset as that last 1.5 HP at redline isnt a make or break and you wont be hanging on the redline all day long. One need only price out having the pistons and liners re made for justification of installing those.

Look closely at the pistons for a batch marking, I wonder if they are the same as the ones I am using. I had a friend at Cosworth at the time who researched what they had made for other teams and made me a few sets of those. I will photo a new extra I have and see if they appear identical. Any markings on the side of the rods near the parting line?

As your use will be entirely different than what it was designed for you might want to consider putting back in some of these items for longevity. Making replacement parts is a humbling affair that might be able to be put off for a long time with them in place. I suggest you have further to go before reversing direction, you have a unique piece of history there.

 

When Angelis and I e-mailed over this, I speculated this was a 40 hour engine (i.e. leMans is a 24 hour race + practice and cooldown lap).

But at least we are in the same ball park.

Now about those factory F348 cams--anyone have the timing numbers?

 

Looking good Sy!

 

I see some pitting on a combustion chamber, as well as some dents on the crankshaft counterweights...

Usually they stand for some past misaps... Are you aware of any?

 

Sure looks familure....
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Agreed. The life span in my opinion is based more on the cam belt and valve train than anything in the bottom end. Rods, pistons, liners, crank... all should last a fairly long time if everything remains intact at speed.

My experiment of "how long will it last with XXX cams...?" Once I started feeling it fall out of time, I chickened out. I have far too much time and money in the engine to see what would survive when the belt didnt. I now feel I know how much is too much cam. It was interesting seeing that the bottom end would take more than I asked of it. It hammers out the main journals a bit on a few of the bearing saddles but that is expected with no harmonic balancer of any kind.

 

The reason I desire F348 valve timing is illustrated as follows:

At 8250 RPMs, the point of maximum power in the F355 engine, then, in order to move the peak power to higher RPMs, one needs to keep the exhaust (and intake by extrapolation) open just as long* as it was open at peak power. The following table emerges for the F355 engine:

7200 221 degrees
7500 229
7750 237
8000 244
8250 252
8500 260
8750 267
9000 275
9250 283
9500 290

Since this engine has an intake much more like that of the F355 (velocity stacks,...) tan the F348, it should (first order breath something more like the F355 and thus need cam timing more like the F355.) Thus for peak power nearer 9000 RPMs, where this engine will have a lot longer lifetime, you shold be looking for a duration of 275 degrees. With actual F348 cam timing I could figure this to a greater degree of accuracy.

Also note, you will want the headers to have a length closer to 26"-27" than the 31" for the F355 and <I don't know what> for the F348 to get the full 9000 RPM power out of this thing.

A 275 Cam would normaly end up being timed something like EO = 71-72 BBDC EC = 23-24 ATDC (which almost has a streetable overlap).

But, F348 cam timings would do wonders for this calculation experiment.

 

How much longer do you think you'll have to wait, Sy?

All the best,
Andrew.

 

Great info here.

i am currently rebuilding my heads and have flow tested them for a base line. OEM intakes are 30.5mm and are on the small side. OEM ex are 27.5mm and am planing to leave them. I am going to try and put 34mm intake valve in it and from the pics i see your LM heads have about that size. Are they 34mm sy?

I'm glad to see it is posible. Has anyone experienced doing this that can shed some light on any problems encountered... such as going into water jackets?

1st pic is the LM head, 2nd pic is OEM head. Big difference in valve area here...
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Also, is there enough meat in the stock pistons to relieve them for the bigger valves? I'm hoping the reliefs in Sy's pistons are so large because of cam lift....