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Discussion Starter #1
I am in the process of putting together an engine for the GTR.

I will be using a Tomei RB28 kit with 86.5mm pistons to give about 2740cc. I will be running 700cc injectors and GTRS turbines.

I am looking to get as good a response as possible and probably a power band of about 5000RPM-8500RPM.

On the old engine, I was using Tomei PONCAMS (260/260, 9.15mm lift). I'm trying to decide what cams to use on the new engine. Will the PONCAMS breath enough for the bigger bottom end?

Or should I use Tomei PROCAMS? Thinking about 10.25mm (260/260deg). Will the low end response suffer? Will the idle still be okay?

I already have a set of Tomei type A valve springs, these should be okay?

Also, what extra hassle to I have to go to to fit the bigger cams? Am I right in asssuming that the smaller base circle of the Tomei cams will mean I don't have to machine clearances in the head? I will need to use the Tomei lifters though, won't I?

Will adjustable cam gears be worthwhile? Will I need a stringer timing belt?
 

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280 deg 10.8mm lift will give you a 5krpm to 8500krpm+ powerband IIRC.
A balance pipe exhaust manifold is essential with GTRS turbos.
 

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Discussion Starter #3
COSSYCam said:
A balance pipe exhaust manifold is essential with GTRS turbos.

Even with a 2.8l bottom end?

It wasn't too bad with the stock bottom end after a lot of tuning.
 

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Discussion Starter #9
I don't really want to run a balance pipe manifold.

Can anyone answer my cam questions?
 

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MIK - I'd use the adj cam gears on the new cams if I were you. I know you will have to reshim with the larger cams. TBA, looking again at your currnt poncams, I'd give them a go with the GTRS and 2.8.

I know on the 2.6 the 260/260 @ 9.15 poncams are good in the top of the rev range. A friend has a set and they are not really well suited to it (too many revs to get the best out of them). for my engine (2.6, HKS GT2530's PFC, 700cc etc...) I will be going for more lift, less duration. I'm a big fan of response in the low- mid range.

you might find your current cams work well, but there are a few sites around that help you calculate your best cam profiles and lift - can't remember any ATM though...

can't see why you would need the balance pipe???
 
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