Turbo help

[GregBranton]

Alright, some of you may have seen another thread I had about my plans for my car. Anyway, I'm ready to start buying now.

My plan was to get the Garrett 2871R turbo but, I then came across the HKS GT-RS turbo kit that is available for my rb20. This route would be much better for me because I would like to get as close to a bolt on as I can as I'm living in Northern Canada and when I get home in the summers I would like to be able to use my car more then wrenching on it.

Would the GT-RS suit my rb20? 90% of my driving will be on the street and highway or the few times that my group of friends head to the drag strip for a few runs for fun.

Ideally I would like to have over 300whp.

Also, I already the rb25 turbo in my car.

[Skym]

If have fuel system upgraded, ECU tune, oil cooler, metal headgasket, FMIC, etc (basic supporting mods). Can get more rwhp with cams, equal length exhaust manifold (look at SR20DET with GTRS turbo, same mods apply, except bigger throttlebody mod, as RB20DET already has a 60mm throttlebody when stock). A GTRS turbo is good for around 375rwhp with cams, exhaust manifold, etc (more or less hp, as each engine is different) with pump gas on SR20DET and more hp with E85 or similar gas + ECU tune to suit (50hp+).

[92GTSTproject]

reg rb25 or the rb25 neo turbo?

[GregBranton]

Skym, you're awesome! Thanks for the response!

I'm fairly sure it's just the regular rb 25 turbo. It was on the car once I bought it, how Would i distinguish between the two?

[GregBranton]

Skym, Say if I were to keep my stock mani and cams, what rpm would I be getting into full boost with this turbo?

Also, which cams and manifold would you recommend? I wouldn't want to have a huge difference with the cams from stock.

[Skym]

Not sure, as haven't tried that turbo, but on SR20DET it's somewhere around 4000rpm for peak boost with HKS cams (I think was 260 duration intake, 256 duration exhaust with adjustable exhaust camgear, VVT adjustments), equal length exhaust manifold, etc (I think is a common setup on some drift cars in Japan).

GTRS turbo is similar to stock T3/To4E turbo on GTS-R (Group-A racing version of RB20DET) and that turbo reaches full boost around 4800rpm with stock cams (248 duration on intake cam, 240 duration exhaust with GTS-R R31 RB20DET head vs 240 duration on both cams with R32 RB20DET head). You can play with cam timing with stock cams via adjustable cam gears, which helps turbo to reach full boost roughly 500rpm earlier (might get better spool result's when have adjustable wastegate actuator, electronic boost controller).

With adjustable cam gears you can modify stock cam gears to be adjustable, as they have stronger teeth and last longer.

You should get better response with stock exhaust manifold (exhaust gas takes shorter time to reach exhaust wheel on turbo), but is known to cause a restriction over 6000rpm (drop in torque on dyno graph usually happens at around 6000rpm).

Equal length exhaust manifold makes the cylinders burn cleaner (allows more oxygen into cylinders which results in a leaner A/F ratio), as more exhaust gas enters exhaust manifold runners instead of backtracking into cylinders and spoiling the burn.

Also causes a drop in boost level, as there's less pressure between turbo exhaust wheel, head, around 1psi is common with stock SR20DET turbo and can get a bigger drop in boost level with bigger A/R exhaust housing, bigger exhaust wheel.

HKS used to make cams for RB20DET, not sure if they do anymore (just like what happened to the RB24 kit with sleeves, pistons, etc they used to sell before RB25DET was released). Could use 260 duration intake Poncam and 256 duration exhaust Poncam.

The 264 duration intake, 256 duration exhaust cam setup was done on this RB20DET in Canada, so it works -

http://www.youtube.com/watch?v=2na_gunvbcQ

Produced around 300rwhp at 16psi with GT3071R turbo -

http://www.youtube.com/watch?v=xkoZv2q-3nY

Or if have the $$$, 270 duration Procams (both cams are 270 duration) with new solid lifters, valves springs, retainers to suit which from dyno testing I have seen on RB26 head, produces more hp, torque down throughout powerband than with Poncams.

With exhaust manifold, 6boost or Sinco Customs steam pipe exhaust manifold that have thick piping, thick flanges, so won't crack.

[92GTSTproject]

the neo turbo is ball bearing reg is journal bearing