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Discussion Starter #1
I'm new to RB26 business but I did a lot of cam testing on my turbo charged Honda B18C6, with the final conclusion that on this engine the best results can be achieved with a long duration in and shorter duration ex cam. We achieved a slight hp gain (compared to equal duration cams) but a big gain in torque.
Reason was with the shorter ex cams we where blowing less fresh air fuel mixture out of the exhaust and therefore got a better cylinder filling (don't know if this is the correct technical term in English).

I did some research reagrding the RB26 on camshafts durations and there I came across that some people are using longer duration cams on the ex than on the in.

What's the advantage???

Why not also use longer in and shorter ex cams???

Anyone ever tested different lift on in and ex cams???

please comment...
 

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Turbine back pressure is one of the main deciding factors on exhaust cam duration, plus whether fuel economy and emissions have any importance to you.
 

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Discussion Starter #3
Turbine back pressure is one of the main deciding factors on exhaust cam duration, plus whether fuel economy and emissions have any importance to you.
So longer ex means better economy and emissions???

Found out yesterday that Mine's Stage II Engine also uses a longer in with more lift and a shorter ex with less lift (260°/10,2 IN 252°/9,5 EX), so basically such a setup should also be a good idea in a RB26.

Anyone any other experiences with different setups???
 

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So longer ex means better economy and emissions???

Found out yesterday that Mine's Stage II Engine also uses a longer in with more lift and a shorter ex with less lift (260°/10,2 IN 252°/9,5 EX), so basically such a setup should also be a good idea in a RB26.

Anyone any other experiences with different setups???
most RB26 dyno sheets i have seen suggest equal lift+duration cams are good, but a higher inlet duration and/or lift may gain power,
[even on huge gt42 size turbos]

most RB dyno charts i have seen with a higher EX cam than IN cam [duration and/or lift] are not that impresive. I think as standard the nissan OEM cams the inlet is higher in duration and lift mm.
*********
any dyno charts to prove me wrong please post up, as much info as possible is best for our RB tuning
 

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Discussion Starter #8 (Edited)
what spec/s RB engine and turbos are you looking at doing?
and rpm limit ?
To be honest, I'm not sure so far...

I'll defo stay twin as it will be a street weekend toy which will see some track action from time to time. I'm aiming at the 500-600+ bhp.

At the moment I'm checking out all opportunities and do a lot of reading/searching and looking out for other experiences with different setup's.
The whole turbo upgrade is planed for the next winter (2010/2011), the engine rebuild hopefully a year later (depending on my funds).

Turbos will be GTSS or GT2530KAI (if I could just decide...)

Exhaust will be Tomei Expreme Mainfolds, HKS Outlets, HKS Downpipe and HKS Hi Power Silent, de-cat

Engine will get forged, but not immediately (due to costs), perhaps HKS 2.8 stroker???

all additional mods like oil pump (Nismo), water pump (N1), clutch (Nismo twin), injectors (Nismo 600cc ???), FPR, fuel pump, Nismo long runner intake mainfold...

Headwork, not sure at the moment as it will depend on turbos. defo cams, valves, valve spring, retainers, and everything else that will be needed.

Guess I won't raise the factory RPM limit too much (8 - 8,5k). The dyno will show when the tubbies run out of puff anyways.
 

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My gtr has 280 degrees on inlet and 290 on exhaust with 11.5mm lift if im not mistaken, sounds like a motor bike idling, and doesnt technically pass mot... but fuel economy isnt too bad with proper tuning, as always it depends on how much you're hammering the car really
Not really low or mid range camshafts, but my powerband is from about 5k rpm to 9.5k so it doesnt matter too much anyways (running a t76 turbo btw)
Its a bit too extreme for a road car though, and im thinking of dropping down to 270degrees so it's a little tamer :)
 

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To be honest, I'm not sure so far...

I'll defo stay twin as it will be a street weekend toy which will see some track action from time to time. I'm aiming at the 500-600+ bhp.

At the moment I'm checking out all opportunities and do a lot of reading/searching and looking out for other experiences with different setup's.
The whole turbo upgrade is planed for the next winter (2010/2011), the engine rebuild hopefully a year later (depending on my funds).

Turbos will be GTSS or GT2530KAI (if I could just decide...)

Exhaust will be Tomei Expreme Mainfolds, HKS Outlets, HKS Downpipe and HKS Hi Power Silent, de-cat

Engine will get forged, but not immediately (due to costs), perhaps HKS 2.8 stroker???

all additional mods like oil pump (Nismo), water pump (N1), clutch (Nismo twin), injectors (Nismo 600cc ???), FPR, fuel pump, Nismo long runner intake mainfold...

Headwork, not sure at the moment as it will depend on turbos. defo cams, valves, valve spring, retainers, and everything else that will be needed.

Guess I won't raise the factory RPM limit too much (8 - 8,5k). The dyno will show when the tubbies run out of puff anyways.
for that spec i would go for drop in cams [no headwork needed], tomei poncam 260/260 9.1mm lift, or GREDDY/GREX 264/264 9.1mm

maybe fit some tomei type-a valve springs if your going for 8500rpm
 
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