Need Some Advice On Reducing Lag/ Increase Response. Cam Choice?

[drgtr7]

Hey guys,

I've tried searching but couldnt really find much.

Currently making 347 rwkw

hks2540's i think - full boost of 22psi at around 5500 ish

powerfc

tomei adj gears

bosch 044

ported manifolds

hks dumps

hi-flow cat

z32 afms

sard 800's

Running standard internals

NOW to my question... How can i increase turbo response? Cams? What cams would be suitable Im hoping something along the lines of drop in i.e. keeping everything else stock.

I want a reliable driver also - and im 100% sure this car wont see a track day or drag strip plus i have shift light set at 7000rpms.

Lag is starting to annoy me and i really don't know what to do.. i cant afford to take out the turbos and buy and sell -9's or -5's.. What can i do to make the lag a little bit better/bearable?

Please don't flame, I'm asking a genuine question.

Thanks all

Edited October 31, 2012 by kinggtr

[KiwiRS4T]

If you don't want to change your turbos then its just a matter of tuning to get as near as possible to the result you want. I would guess cams should stay stock but timing would need adjusting via the two adjustable gears (that's what they're for!)

Seems like you are in the same town as Status tuning so give them a ring and make an apointment - be prepared to spend around $1000 more or less for a decent tune.

[Piggaz]

I know you said you don't really want to change turbo's, but those 2540's are probably the worst lowmount setup on a GTR for any type of "'response". Cam timing and tunes are only gonna help so much.

A set of type R Poncams if you must buy a set of bumpsticks would be the go.

[SiR_RB]

And make sure your exhaust doesn't have "step downs" that'll cause unnecessary back pressure

Turbos that size and an engine only revving to 7000rpm would be a dog to drive...

[Lithium]

As already mentioned, well aware that you said a turbo change is not what you are wanting to look at doing - but at the end of the day the cams aren't going to be a budget mod and are really going to make so little difference you're going to wonder why you bothered imho, and will eventually have to do something drastic to polish the turd that is GT2540s (if you don't just replace them).

Honestly the most logical thing to do is change the turbos, as funnily enough anything else you do is not going to change that they are GT2540s and as such are going to behave like them.

[AngryRB]

a tune on eflex and a good boost controller could make it bearable and reduce it down possibly 500rpm, did on mine

[SiR_RB]

all this money you would spend on cams/install/tune blah blah you might aswell rip these out one weekend, put in some -9 turbos and sell these HKS 2540 on !

[Serpandrew]

Can I ask if you can't afford to spend the time removing the turbos or is it just a matter of money?

If it's just money i'm sure you can make a decent bit of cash back selling those and buying second hand -9s/-5s.

But yeah otherwise, who tuned the car and got a dyno graph of it currently? And have the adjustable cams been used to lower the power range?

Edit: What front pipes and cat back are you running?

Edited November 1, 2012 by Serpandrew

[discopotato03]

I'm not an RB26/GTR person but I'd look at it like this .

HKS effectively replaced the old "GT2540s" , which in todays speak are actually GT2876Rs , with turbos called GTRSs which are a GT2871R in 52 compressor trim .

People here say that it takes a specific combination of parts and good tuning to make GTRSs work on an RB26 and they actually use smaller but more modern compressor wheels than the old 2540s .

You could try all kinds of ways to work around those turbos but at the end of the day they are not a well though out turbocharger and you can do better .

Simply too big a compressor for the turbines to drive and thats what makes them lazy .

I think the designed for the purpose GT2859R (GTSS) are the go because they make boost and torque in the rev/speed range you can use in a street GTR .

Pretty sure you'd still make 300+ Kw but you'd drag the power range down possibly 1000 revs if not more .

So your call , either GTSS or inaptly called GT2530s I think .

A .

[Piggaz]

-9's are SS' s

-5' are close enough to 2530's.

Spend the money and rip those turbos off mate. You're about to drop a bomb of money and really, you're not gonna get the result you're after.

[Dose Pipe Sutututu]

what are your cam gears dialled in as?

You could "possibly" get them to spool a tad earlier if you advanced the intake cams and retarded the exhaust cams a tad. A few people have gotten their GTS-ts to spool a tad earlier by retarding the exhaust cam gear only.

[drgtr7]

Hey guys

Firstly thanks for all your input on this matter - ill upload the tune soon.

Not to sure what's been improved from the cam gears other then an obvious lift on all parts on the graph.

I swapped out the gfb manual Bc and swapped it over for an eboost street and don't a few adjust I'm getting a rushing boost feeling from 3000 rpms and full boost at 4800 5000

Could they be 2530s? I also noticed an intercooler pipe leaking which I sorted out.

Lastly I spoke to my tuner and he explained how opts for a smooth graph and smooth power delivery. Maybe im just used to the standard response of the ceramic turbs?

[33GTRV]

best way to fix your lag and response is to throw a 6262 at it. You wont look back

[drgtr7]

^ If it wasn't for EPA ......

Heres the dyno graph a few of you have requested:

[GTScotT]

Peak torque is 3/4 up the powerband, no wonder your not happy..

Im really with the others and will say spend wisely and just get real turbos. To match the peak you will need -5s. Check serial numbers before you do anything, obviously..

[STATUS]

wind a shload on advance on the intake cam leave the exh at zero, should be around 300-400rpm in that alone.