Rb26 Gt-ss Turbos - When Should Boost Kick In?

[justinfox]

Hi guys,

I have a fully rebuilt RB26 in an R32 GT-R. GT-SS turbos, HKS everything else (manifolds, pipes, pistons, rods) + Tomei poncams.

As you've guessed from the above, the car is built for response.

I took it out on track yesterday (Wakefield) and damn it's laggy. Boost starts kicking in at 4500rpm. Is this normal? I also drive an EVO 6.5 dead stock and that kicks the boost in at 3000rpm. I know I shouldn't be comparing the GT-R to the EVO. But I just wanted to know whether or not full boost at 4500rpm is normal?!

Maybe it's more about the car being so slow off boost. It's ridiculous, slower than a Barina off boost!!! Any suggestions, feedback, opinions, all appreciated. Thanks.

UPDATE UPDATE UPDATE 29/NOV.

It was the boost controller! Wasn't set up right. Wheeeee!!! Much more response, a whole lot smoother on boost too. Now to take it to the track again! Shame it's so damn hot at the moment.

Edited November 29, 2006 by justinfox

[GTRsean]

Funny! GTSS turbs were what I was going to get due to responsiveness.

It could be: Tuning what sort of mapping was done in the spool up low revs area.

Restriction in exhaust?

Maybe if you had GTRS turbs you would have this issuse but you don't and thats crazy it's so laggy!

Anyway good luck on your problem.

[blk180]

sounds crazy thats as slow as my 2530s with stock dump/fronts and stock cams. how much boost u running,when is it making one bar, have dyno sheet

[Blitz]

Hi guys,

I have a fully rebuilt RB26 in an R32 GT-R. GT-SS turbos, HKS everything else (manifolds, pipes, pistons, rods) + Tomei poncams.

As you've guessed from the above, the car is built for response.

I took it out on track yesterday (Wakefield) and damn it's laggy. Boost starts kicking in at 4500rpm. Is this normal? I also drive an EVO 6.5 dead stock and that kicks the boost in at 3000rpm. I know I shouldn't be comparing the GT-R to the EVO. But I just wanted to know whether or not full boost at 4500rpm is normal?!

Maybe it's more about the car being so slow off boost. It's ridiculous, slower than a Barina off boost!!! Any suggestions, feedback, opinions, all appreciated. Thanks.

Something is definately wrong there Justin.

I have GT-SS's on my car and they are probably the most responsive turbos you could pick for your RB26

I will check my dyno sheets later tonight and get back to you with some more info if you like.

[RellikZephyr]

yeah im a bit curious about this too

cause i am planning on getting GT-SS's for my gtr and if thats the lag i dont want them

RellikZephyr

[Bass Junky]

Boost controller?

Tune? rich or lean?

what's it like on the dyno?

Are the Cams dialed in correctly?

[Blitz]

yeah im a bit curious about this too

cause i am planning on getting GT-SS's for my gtr and if thats the lag i dont want them

RellikZephyr

Easy tiger, dont go changing your plans because of this - there is something else going on thats causing Justins turbo lag

[godzl1975]

thats ok mine kick in at full boost @ 5700 lol

[Blitz]

thats ok mine kick in at full boost @ 5700 lol

Your kidding right?

[Roy]

Your car seems to be a ball ache. First the 2530s were laggy, now the GTSS. Have you been for a ride in other cars with similar setups. You should have gone for a ride in the white R33 GTR at Wakefield, basically a std motor with turbos bigger then yours.

If its worse then your car then there is a problem with your car. If its about the same then you have to come to terms that you are running twin turbos, which can provide almost 600hp of airflow, but with only 2.6L... it is a turbo car.

Your EVO runs a small little turbo with boost up the brazoo...so will always be responsive, will especially feel that way because of the gearing, weight and turbo of the car

[R31Nismoid]

GT-SS should be on the juice virtually like a standard turbo, and just have a LOT more top end compared to the stock turbos.

There is something wrong with

1) Boost Control

2) Tune

3) Cam setup

4) Exhaust restriction

Thats some stuff go get started with, but for anyone else thats reading this, this is NOT normal for GT-SS turbos.

So dont be put off by them, this setup just has issues

[Roy]

Who does the work on the car? If they couldnt get the 2530s do be responsive enough, and now the GTSS, then i would be considering another mechanic / tuner.As the engine has the best of everything yet you dont seem to be happy with it.

[justinfox]

I am pretty sure it's the tune. Here's my dyno sheet.

[Bass Junky]

Have you got it against Boost ?

It's a bit wavey

[PhilGTR]

I am pretty sure it's the tune. Here's my dyno sheet.

I have a similar problem with my r34n1's and my mechanic reckons its the tune cuz my exhaust cannot be blocked (or so i assume as I have a new cat as well as front pipes) So im going to get mine road tuned in a couple of weeks to see if they can find the problem. Good luck with yours!

[justinfox]

That's all I got dyno sheet wise. It's on 1.2bar.

Exhaust is fine (HKS manifolds, piping kit, front/dump, high flow cat + Kakimoto Regu96 all the way back).

Boost is controlled via AVCR. I would love to get someone else to tune it but that will definitely void my warranty on the engine as currentlky the builder is the tuner. Looks like I'm in a situation then huh?

[Bass Junky]

Do you know the boost settings and gain settings on the AVCR?

What type of computer do you have?

[PhilGTR]

Do you know the boost settings and gain settings on the AVCR?

What type of computer do you have?

Hmm interesting i may have to check my boost controller see if they set the gain really low!

[Blitz]

That's all I got dyno sheet wise. It's on 1.2bar.

Exhaust is fine (HKS manifolds, piping kit, front/dump, high flow cat + Kakimoto Regu96 all the way back).

Boost is controlled via AVCR. I would love to get someone else to tune it but that will definitely void my warranty on the engine as currentlky the builder is the tuner. Looks like I'm in a situation then huh?

Justin, I dont know of anyone who has ever tried to claim on a warranty for an engine rebuild!

Take the car to CRD and get Jim to sort it out or at least check the tune without adjusting it so your warranty is safe but you will hopefully then know exactly whats going on/holding you back.

[justinfox]

AVCR settings, no idea. Power FC ecu.

Blitz - CRD would for sure sort it out. I totally agree. Looks like I have to find a tuner and forget the "warranty".