Things I'd like to change on my S50B32

[Pingu]

Just a short list of things to consider to improve the standard engine. Some are impractical without spending big bucks, some are easy to do, some are free (but they will all affect each other)...

Add a scoop to the air intake. This will have to be carefully designed and monitored to ensure the engine doesn't go "over-lean" at high speed.
Less restrictive air filtration.
Intake system should be heat shielded to reduce the effects of under-bonnet heat transfer.
6x MAF instead of 1.
2 plenums instead of 1.
Intake tract tuned to a speed the engine can attain (eg 6500rpm).
Throttle plate and shaft cross-section could be reduced more and the throttle plate leading and trailing edges chamfered.
Thermally isolate the throttle bodies from the cylinder head.
ECU that corrects fuelling for each of the cylinders, not just for each bank (1-2-3 & 4-5-6).
Improve the cylinder head. It's already very good, but not excellent. Minimum cross-section is 333 sq mm at the valve stem.
Inlet valve should be confirmed to have square edge profile.
Inlet valve stem could be reduced.
Inlet valves and springs could be lightened.
Exhaust valve should be confirmed to have a rounded edge profile.
Exhaust valve stem diameter could be reduced.
Exhaust valves and springs could be lightened.
Camshaft is ok.
Piston weight can be reduced.
Con-rods can be lightened.
Piston/con-rod/caps can be balanced to better than the current +/- 4g.
More heat shielding around the exhaust headers and possibly add a fan (or ducting) to blow the hot air under the car in a controlled way.
Exhaust header entrance area increased and a step created.
Exhaust header length and diameter tuned to a speed the engine can attain (eg 6500rpm).
Exhaust collector tuned to a speed the engine can attain (eg 6500rpm).
The diameter of the exhaust pipe is very close to optimal.
It's very difficult (nigh on impossible) to optimise the exhaust length because of catalytic convertor and muffler. The wave created by the closing of the exhaust valve is seriously corrupted by the cat and the muffler, as is the wave from the tail-pipe.
The crushed section of the exhaust muffler pipe should be replaced with a pipe of the same cross-sectional area of the rest of the system.
Muffler should be de-restricted.
Tail-pipe should be opened up. The current tail-pipe has a reducer down to 40mm.

 

[Althulas]

Interesting I like to see what you decide to try out, I like to see what idea you come up with for removing heat from the engine bay though as it is quite toasty under the hood after a drive. I was quite surprised at how warm it was to be honest.

If your going for the 6500rpm I would upgrade your conrod bolts if you have not done so already as I had number 5 pot let me down after some very spirited driving causing me a damaged but fortunately salvageable crank. I’m still weary of a future failure but time will tell once I get to finish running it in.

 

[Pingu]

6500 is just the tuned target. The standard intake is tuned to 8500 and the exhaust isn't tuned at all. The exhaust is a mish-mash of different ideas. Different parts are tuned to different engine speeds. The headers are different lengths (not a bad thing), but the header and the cylinder head port are the same sizes (not always a good thing). The collectors are too small.

I've been doing lots of calculations and measurements of the engine and I've been speaking to some engine designers on an engineering website. Their conclusion was leave it alone. My conclusion is "if you don't try it, you'll never know".

I built a manometer and learnt about inlet and exhaust tuning.

Lots of auto myths blown away, especially to do with flow management.

I've concluded that there are a lot of things are on the car that are there to make it quieter. Most of these can be removed and still be legal.

 

[Althulas]

I admire your knowledge and be will interesting to see if you can gain results despite other advice.