Looking for more high end power, turbo or cams upgrade?

[JDMSIL80]

I am very impressed with my GT28R, it has very quick spool and loads of midrange torque for daily driving. However, its power band seems to be a little short that I could feel the power started to fall off around 6000. I was hoping it has more high end and continue to make power upwards to 7500. I was thinking to get HKS or Tomei 8.5 cams with 264 duration, but some have suggested me to upgrade the turbo to GT2871R which should give me more high end power. Which option would you guys recommend?

Currently my motor has GT28R, FMIC, GT-R injectors, XS turbo manifold, 3” turbo back, Z32 MAF, Blitz EBC, Power FC.

[Kouks]

cams would help out a bit, id go with HKS 264 cams I&E. Ultimately though, if you want alot more top end, go with the .86 ar gt2871r.

The gt28r that you have now should breath well till 6800 or so.

I suggest the cams first, then an upgraded intake manifold, have you seen the CPC Intake manifold for the ca?

Then if you want more power, and subsequently more lag, then go with the 2871 with the .86ar, and bigger injectors.

[JDMSIL80]

Thank you for your suggestions. I'll mostly likely do it the way you said, cams and then intake manifold just to see if thats enough to make up for the high end power.

Base on your experience and looking at my mod list, what is the maximum boost I can dail-in for my setup? My motor is bone stock and the most I have pushed so far is 14 psi. Can I boost higher than this if tuned properly?

[teddy]

It's all about the tuning. You could run that thing up to 20psi on a stock block and stock headgasket if its tuned well enough. I do believe Dee did this on his motor. But, I woudlnt suggest running 20psi all day either. I would suggest running about 10lbs on a daily basis. If you're looking for cams, I do think you can still pick up Tomei's for a reasonable price seeing as the HKS cams are discontinued. But dont think about running 254's, you wont notice much of anything with them.

Another suggestion would just be to port and polish the intake manifold, it's much cheaper than buying a custom manifold.

[float_6969]

My vote: Cams and intake work/replacement. That GT28R is a great turbo and should support 14psi to redline.

[JDMSIL80]

^Thanks for the invaluable suggestions.

Can GT28R support boost level & make power above 14psi?

I remember reading someone's post saying 15psi is the max on certain turbo chargers, anyone more boost is pointless because it wouldn't produce more power. Just wondering if its the case with GT28R.

[teddy]

IIRC, the gt28r starts to lose efficiency around the 17-18psi area.

[float_6969]

Agreed. I think you can safely run it up to about 17/18psi w/o dropping out of the peak effeciency range. You can run more, but you'll start to heat the air up more than nessicary.

[dattodude]

Yesterday, I asked for a quote by greenline.jp, and they tell me that Tomei have stopped making CA18 Solid lifters mid last year. And they are currently unavailable. They are still in the catalog, but unavailable. I got a set of 270/9.25 cams 2nd hand that I'm eager to get into my CA18det, but without the lifters, I'm kinda screwed. I might have to make and get them heat treated myself.

If you go the large overlap poncams, you'd be much better off. These solid lifters are becoming a pain in the butt to get sorted out.

Chris