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Rod Penrose's New car project

46315 Views 291 Replies 69 Participants Last post by  twaluminum
Australian drag racer Rod Penrose is building a new bug body style race car!

To be on the track in 2009!

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I have 2 lean cylinders ( 1 & 3 ) and 2 rich cylinders ( 2 & 4 ) and can't comprehend why if it is all under pressure
If you are still running the same intake manifold as in page 3 of this thread, I'd say that you have a distribution problem.
You may be able to diagnose it in a flowbench, test each pair of runners with the other hole blocked and compare the #'s.
Quick and easy would be a T-section after throttlebody and symmetrical runners to the cast manifold sections.
Extra volume before T-section would also help by slowing the air down for the 90deg turn ahead.
I have ported loads of VW OEM dual port manifolds and it is very easy to get uneven distribution on those, I see a
similarity to your intake runners.

Pekka , I will put the manifold on the flow bench and let you know the results . I will also modify the manifold and re flow it to see what type of difference it makes .
I have removed the engine and dismantled it to find it all good and ready to re-assemble . I would like to know why my piston tops are a different colour . the engine was shut down at full throttle @ 150 mph and the EGT difference between the 2 cylinders was about 55 degrees . I use methanol and I don't know why the difference . I am not worried as when I clean the pistons they will all look brand new . I also need to know why the piston rings move in the pistons . I set them a certain way and when I removed all 4 pistons the rings were all over the place and no 2 were the same . I had 118 psi in # 1 , 120 in # 2 , 120 in # 3 and 128 in cyl # 4 . I suspect the difference in compression is due to the position of the rings as the best compression was in the cylinder with the best set rings . I have vacuum tested the heads and the valves are all perfect . When I last freshened the engine with these new rings my crankcase pressure was @ about 1.2 psi , now after dyno time and track time it has been slowly creeping up to now about 7 psi , ROD.


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I don't know why you have different colors but it may be uneven fuel distribution. While running methanol I have always polished the tops of my pistons to a mirror finish and they always clean up with windex.
RodPenrose said:
Last weekend 8.17 @ 158 mph , ROD.
Hi Rod, did you get the lean/rich cylinder situation solved ?

Owen said:
Ran [email protected] on the weekend!!
Great job!!

Way to go Rod!!

Thanks for post Owen
And the car looks to be doing it with ease... It's kinda odd watching the car accelerate and make barely a sound, and pull so hard, but look like its not even trying.
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