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A race bmw 316, m10, s14, m20, turbo, na, its been the lot!
Think Andy and I may try to get down to Lydden ...
thats nice, i'll be at silverstone!
BARC se are running on the stowe circuit saturday, its only small but theres very little to hit so its a good place to try out whats most likely going to be a spinning top for the first time, and for me its only half the distance of lydden
the stowe test really didn't go to plan, i developed a big end knock! and it seized once i turned it off.
i removed and stripped the engine sunday to find no 1 con rod scrap and the bearing welded to the crank, not to mention the crank 3 thou bent, a load of swarf embedding in the piston skirt a damaged gudgen pin and chipped ring.
to cut a long story short when i modified the oil ways on this block ( something i've done many times before on these engines) i made a small mistake and effectivly shut the oil supply to no 1 main bearing off.
time was really against me as i also had a test session booked at brands on friday, fortunatly i had a spare crank and rod, and set to ordering bits left right and center from Euro parts, BMW and Burtons (pistons are V6 ford)
at the same time my normal day job got really busy and i was working 10 hour days, then working to the small hours each morning rebuilding the engine, thursday night it was ready and i was shattered, i'm getting too old to live on only 4 hours sleep a night, let alone 4 nights running.
i made it to brands, where i had issues with missfires which i gradually ironed out, thankfully the engine seemed as powerfull as ever and the chassis was really good.
my best previous lap times round brands indy was a 55 in my 208bhp non turbo car driving it right on the edge without other traffic in the way, unfortunatly friday there was a lot of slower traffic about, and i never got a good unbulked on line lap in all day, but even so was comfortably doing 55's without really pushing, so with a bit more time in the car we might even get into the 50's sometime this year particulary when i have full power, as the bigger injectors are still to be fitted
After fitting the 750cc min injectors, we have just finished mapping the engine today, and if i say so myself it does exactly what it said on the tin,
the goal was 100bhp more than last year, with low lag and hopefully reliability so i was looking to keep the boost pressure low, which is why i built a big cc 16valver and fitted an rs500 race intercooler, turbo technics built the t38 turbo to give low lag and getting on for T4 power saying it would run out of steam at around 450bhp
the final result
15psi boost, 409lbft 460bhp,
it looks like TT were spot on with the claims for the turbo as cranking the boost up further doesn't actually make more power, suggesting that 460bhp really is its limit in terms of airflow.
one thing that we never actaully did was to play with the cam timing, but then again, i've got more than enough power for now, just need the driver skill to go with it.
Sorry if this is a dumb question.
I looked at the pic of your crank, and thought "why do they have such big counterweights"
What would happen if they weren't there? I am guessing it is something to do with balancing, but why doesn't the flywheel do that. And why do you have to have a flywheel at all if those weights are swinging round in there. Surely not just for the clutch. Though I am aware of seriously lightened flywheels used in racing.
And I should have said "sorry if these are dumb questions."
the counter weights are more important than the flywheel, that just stores energy the engine doesnt actually need the flywheel at all, mine basically weighs next to nothing, the counterweights on the other hand are there to offset the weight of the crankpins and rod/piston assemblies, a fully counterweighted crank suffers much less from tortional vibrations and whipping
that crank has quite a long stroke so i guess that means bigger weights are needed although strangely this crank which is from a 2.5 with 87mm stroke is 4 kgs lighter than the 84mm stroke 2.3 version
just in case you guys missed it elsewhere, i had a cracking first race at brands, won my class came 3rd overal and set the second fastest lap, blinding result and all from this homebrewed beauty which is currently cranking out 460bhp 409lbft on 15psi boost
the second race wasn't so good, it was the first wet race i've ever done in this car, and the thing steamed up so badly i couldn't see where i was going and so drove like an old granny, still i did finish and all things considered 3rd in class and 12th overal wasn't bad
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