Thread: A few GTiR specific questions

So I'm building a GTiR Sr20. I've got the pistons/rods/gaskets figured out, I'm just not too sure about head specifics. I've done a months worth of research on various forums and there seems to be lots of unclear info.


Some info about the car and the goals for it first; The power goal is 500+whp as well as a minimum of 8.5k RPM. The car is a street car that will see the drag strip as much as time will allow. Oh, it's a b13 classic.

1) Cams & vt:
I've read that there are "issues" when using normal sr20 cams with this motor. Is it just noob error, or is it really an issue? I've read about needing to properly shim and that will be of no issue to me. I'm looking at using JWTs4 cams.
What about the vt? Can I use Brian Crower springs/retainers? I figured if I can't find/use normal cams, then I'll stick with stock and use adjustable cam gears to move around the power band as I see fit. With the aid of vt of course.

2) Clutch/flywheel
I've read a few posts here and there that the flywheel is specific to this motor only. You can swap flywheels, but you have to buy the clutch specific for that flywheel and you can't interchange. Do I have that right?
I bought the car already swapped, so I HOPE they left the stock flywheel on there. Does anyone have measurements/dimensions so I can confirm? I really want to use an FX500, but I'm not finding one for a GTiR, only the normal sr20.


For those wondering on the setup.
86.5mm wiseco's with upgraded pin
Manley rods
ACL Race bearings
Custom turbo manifold(or I might just buy one from the classifieds here, theres one I really like)
SP6262
ID1000's
Walbro hp 255lph
GM 3bar
F.A.S.T. ecm
PPG gearset <<<< next year


Thanks in advance!

The R has mechanical lifters, not hydraulic like the other SRs. You can run the other cams but it will wreck havoc on your VT in a short time. In short, just get cams meant for your head. There are TONS of companies that make cams for the R: Piper, Kent, Kelford (they even will do a custom grind for you), HKS, BC, Tomei, JUN, and the list goes on... so you really have no excuse for not finding a cam suited for your needs for the R. As for your VT, the R comes stock with nice double springs and her valves are different than any other SRs. Once again there are a few companies that make custom springs and retainers for the R so if you are looking to upgrade then you have options.

As for the Fly you will need to take a normal SR fly and machine out the bolt holes to 11mm to match the size on the R’s crank. You can get new OEM fly bolts easy: just use the ones from the B15, they are the right size. I think there is already machined fly for sale on the forum if you need one plus I have one too if you need it (cheap shameless plug, PM me for details and pics). I don’t have the stock R fly, so I can’t post up dimensions, so apologies on that. Hopefully someone else will chime in for you.


The R is a special engine. It’s fun, but has a ton of little quirks like what you just pointed out. All the info is out there, you just have to look for it. My advice: look on Oz, UK, and NZ forums; tons of information. Hope this helps and good luck!

Bumping this back up,

thanks for the reply, zer099.

Does anyone know if I'd be able to use stock rods with forged pistons?

Yes. I have 88mm forged pistons with the stock rods. I would be sure to get your rods all balanced ofcourse, but our rods are known to be good up to a good number.

Sweet! I wish all the info was documented in ONE place! It'd make searching so much easier. By that I mean engine specifics. I'm sure I can find all the info in a manual, but wheres the fun in that? LOL.

I'm trying to save as much as possible so I can have a proper turbo manifold/wastegate setup. My plans now have changed from getting Manley rods to using ARP rod bolts and refurbishing the stock rods and honing them out to my exact specs so I can achieve my desired oil clearances.

I'm not new to building and tuning motors, just new to Nissans. Don't know a darn thing about them!

I might just opt for some custom pistons. I dislike low compression! I'm wanting 10:1 or so. Not only will the higher compression help in making power easier, but it'll also help create a better combustion chamber design(flat top piston).

Thanks for the help again!

No worries. I went up to about 9.0:1 when I swapped out pistons. Noticeable changes at low throttle and off boost. I didn't want to push my luck with tuning by going higher plus I have big boost dreams so I like to keep the static ratio low.

Good luck with the build!

Thanks! Tuning is no issue for me. the gnarliest build ive done is a 13:1 motor with a 200 shot of nitrous.