Custom Pistons And Modified Combustion Chamber

[Sydneykid]

Thats okay, but after speaking to some of the big tuners over in the States and Japan they all state that they remove the squish zones and use a custom piston to suit hence the purpose of this post since they arent reluctant to release what combustion chamber/piston design they use that allows high compression (9.0-9.5:1) with a fair amount of boost (1.5Bar) on pump fuel. And before anyone says Japan has better fuel the US doesnt and they still seem able to do it

So what, how much ignition timing have they pulled out of it?

How rich are they running it?

What's the average power?

What's the response like?

In the US they chase the max horsepower number, they don't care about anything else

cheers

Edited June 24, 2006 by Sydneykid

[markr34gtr]

why bother with all this stuff when rb 25 & 26 heads really only need a port job and the correct cam for your application... there are rb25 making 600 rwhp plus std head ported... & rb 26 heads ported making 1000 plus hp...leave alone what already works...

cheers, mark.

Proengines: Thanks very much for your input. I have drawn up some other chambers as you mentioned, I didnt quite understand the one about the V8 Wedge engines so I will wait for a clarification. If you can let me know which of the combustion chambers will work the best.

My engine specs are RB26, high comp (9.0-10.0:1) running 1.5 bar and pump fuel to make 500awkw which is approx 800bhp.

Chamber images:

1. Totally removed squish inlet and exhaust

2. Reduced squish inlet and exhaust allowing flat top piston due to piston entering the chamber where the squish was removed

3. Reduced exhaust squish with a Edyne style piston

I greatly appreciate your's and everyon elses opinion

[Turbine]

In our RB20DET GTS4, TurboX(Greg) spent hours removing any sharp machining edges and blending the chambers smooth by hand.

The compression ratio drop is very small. We have had the boost set at 15psig so far with no dramas.

[CRACKD]

Okay, well I dont want this to turn into a heated discussion. From the impression I am getting people in Australia dont modify the combustion chambers other than polishing and radiusing the edges.

Is it possible to run 9.5:1, 1.5 Bar and Optimax Extreme?

[Sydneykid]

Okay, well I dont want this to turn into a heated discussion. From the impression I am getting people in Australia dont modify the combustion chambers other than polishing and radiusing the edges.

Is it possible to run 9.5:1, 1.5 Bar and Optimax Extreme?

Don't know, never tried it.

I do know 2 bar, 9.0 to 1 and Shell Optimax Extreme 100 ron is not a problem.

cheers

[NXTIME]

Avgas would be cheaper. Pity it's illegal (for street use)

[dontfeelcold]

Don't know, never tried it.

I do know 2 bar, 9.0 to 1 and Shell Optimax Extreme 100 ron is not a problem.

cheers

What setup was that on? RB31DET?