Camshafts And Springs Setup For Gt-rs

[PM-R33]

Hey guys,

Well im going to be doing the cams in my car in the next month or two and have been reading a lot about what to go for. I know a lot of people use the GT-RS turbo for street use so just wanted to get a feal on what people have found to be the best setup. Now im not really going for top end power, mainly to get as much bottem end and torque through out the rev range so bare that in mind.

I've narrowed it down to 256 Poncams with 8.5mm lift on the intake and exhaust. This is what my tuner has recommended aswell for the best "street" setup. I'll change the springs to tomei's aswell which are rated at 8.8mm lift. Would 264 degree cams start losing what i want (bottem end power) or would people recommend that over 256's? Most people go 256's because you don't have to change springs, but if i'm going to be changing them maybe the 264's would be the way to go.

Is it worthwhile doing any headporting/polish or anything at the same time with this setup or would the gain vs money be pretty much fark all? (I should be able to get headwork done at an ok price so maybe it would be worth it?) I've read its mainly for a bit more extreme setups where you notice good gains though

Just wanted some input from a few people on what they have found to work the best with a setup similar to mine to get the most out of this turbo. There's a lot of threads about cams, but usually its with people just wanting to throw the biggest cams that they can get their hands on for big top end which is not what i want.

Thanks

Phil

[NYTSKY]

I have Poncams in mine.And it gives good response and mid range.If you are changing the springs why not look at getting HKS 256 intake and 264 exhaust?

As for the head i would leave it alone as the cost starts to climb and the benefit is marginal with a street setup like you are after.

[joeyjoejoejuniorshabadoo]

for lowdown response i've been told by my tuner to stick with stock cams and play with the VCT instead...

discuss...

[R31Nismoid]

^^ same route followed a while ago with my RB25.

Response/power was no different to those with cams in the end after comparing a few results mine really was not all that different.

Depends if your tuner knows what's going on

[joeyjoejoejuniorshabadoo]

with mild cams (tomei bolt on's etc) do you have to lose bottom to gain mid?

Edited March 18, 2008 by joeyjoejoejuniorshabadoo

[PM-R33]

Pretty much running a microtech so no VCT, after discussing about running an external VCT controller with my tuner he said it can be done, problem is if the controller fails and the tune is setup for the VCT being active (due to it running different cam setup or whatever it actually does to the cam when active) it can cause damage to the engine with the tune not corresponding to the cam. I'm probably wording that a bit wrong, in my understanding i guess it could start knocking with the tune not being setup for the right cam timing?

I've compared my dyno graph with a couple of people that have cams and all of them have a lot more midrange and bottem end power, which is what im mainly after.

With the 264 on the exhaust side, what kind of difference would that make compared to a 256 on the exhaust? Talking like real world driving differences.

Edited March 18, 2008 by PM-R33

[joeyjoejoejuniorshabadoo]

the cars that you compared them to... were they VCT enabled though?

sorry for the threadjack but i'm in a similar boat... and have been told by a very reputable tuner not to go that way...

although i have a PFC and vct still

[PM-R33]

All good mate, the more information we can get the better for both of us.

Yeah you're right, they may have had VCT enabled because one was running a power FC and the others im not sure about. So annoying that aftermarket shit doesn't support a VCT feature. Hmm so many tough descisions and so much money involved. I just want more midrange power and a lot of people i have talked to all say that with cams the GT-RS comes alive, so i dunno.

I was thinking the smaller duration cams (256's) with more lift over factory would give that better midrange power compared to 264's which would move the power curve up a bit.

Why did your tuner say not to go with cams? Surely some poncams or equivalent would make more power in the rev range then standard cams?

Edited March 18, 2008 by PM-R33

[joeyjoejoejuniorshabadoo]

tomei poncams work with VCT and are the usual choice to go with a gtrs

smaller cams can make less peak power but have a better transient response... i.e. comes on boost faster...

(or so is my understanding anyway...)

ash? *looks around thread*

[Adriano]

AFAIK all the microtechs have an auxillary output, why not set that up to the vct. I had an old digi, and even that had am rpm aux output.

[adgey]

I went the HKS route with the 256 in and 264 out. Haven't got the car back yet so can't give you real life experience but from what people told me they go the larger exhaust cam to help get those gasses out but get the smaller duration intake for a less lumpy ride in the street car.

I have a HKS 256 duration intake cam I'm trying to get rid of ... the one that retains the VCT (I went adjustable pulleys and bought the wrong intake cam )if you decide to go down that path. Never been used and a lot cheaper than a shop. Drop me a pm if your interested

[wolverine]

the 256deg poncams should bring the boost threshold down and should make more everywhere. mild head work and port matching can definitely lower the boost threshold as well.

it comes down to $$'s whether you feel its worth it. total extra hp won't necesarily be massively higher maybe 15-25kw but response will be pretty hard to beat as the power curve should be moved to the left.

[PM-R33]

AFAIK all the microtechs have an auxillary output, why not set that up to the vct. I had an old digi, and even that had am rpm aux output.

Really? I didn't know that. So i can set up this auxillary output as an RPM switch to go off the solenoid on the intake cam? Don't suppose you know how to do this?

I went the HKS route with the 256 in and 264 out. Haven't got the car back yet so can't give you real life experience but from what people told me they go the larger exhaust cam to help get those gasses out but get the smaller duration intake for a less lumpy ride in the street car.

I have a HKS 256 duration intake cam I'm trying to get rid of ... the one that retains the VCT (I went adjustable pulleys and bought the wrong intake cam )if you decide to go down that path. Never been used and a lot cheaper than a shop. Drop me a pm if your interested

Yeah let me know how you go mate.

the 256deg poncams should bring the boost threshold down and should make more everywhere. mild head work and port matching can definitely lower the boost threshold as well.

it comes down to $$'s whether you feel its worth it. total extra hp won't necesarily be massively higher maybe 15-25kw but response will be pretty hard to beat as the power curve should be moved to the left.

That's the main thing i want, as much low down power as physically possible, so if i could get the VCT working and get the Poncams in, i'll be a happy man. I'll find out from my mate how much machining of the head will cost me, if it aint too much might aswell clean it up a bit.

[PM-R33]

Ok i had a look through the Microtech manual and for the Aux RPM output function it says it works by switching a device on at a certain RPM that you program in. However, for the VCT you need the opposite, have it active from say 1000rpm or so, and then you want something to switch it off at say 4500rpm or whatever it goes to.

So could this be somehow rigged up to work?

[paulr33]

whats the reason you are going for microtech?

ive driven my car with VCT unplugged and its just sluggish and lacks power

im not sure it will "kill the engine" it would be unreasonable for the engine to fail if the VCT system is disconnected or fails

the engine check light doesnt even come on if the system fails, theres no active check for VCT in the ECU train so its not an essential part

ie oil pressure and temperature are and can be fatal, hence they have sensors and throw the engine light on when they fail or an idiot light

[paulr33]

external VCT boxes;

http://www.apexi-usa.com/product_gizzmo_de...7&pageNum=1

http://www.nengun.com/power-enterprise/camcon

either of those should give you some external VCT control

it would probably be easier, cheaper and more reliable to use an ECU that supports VCT out of the box

[paulr33]

have you brought the cams yet? if not, dont - try the car without the cams

its a big capital outlay and you find its for zero to minor gains

much like a front plenum change - zero to almost zero gains for $1000 ish

[PM-R33]

whats the reason you are going for microtech?

Allready in the car and fully tuned, car runs sweet other the the VCT not working. If it gives me some gains down low in the rev range id like to get it working. Free power in a way.

ive driven my car with VCT unplugged and its just sluggish and lacks power

im not sure it will "kill the engine" it would be unreasonable for the engine to fail if the VCT system is disconnected or fails

Hmm yeah i dont know, tuner just said if the tune is done for the VCT being active, and then it fails, it could cause the engine to knock. I suppose it depends how aggressive the tune is done.

external VCT boxes;

http://www.apexi-usa.com/product_gizzmo_de...7&pageNum=1

http://www.nengun.com/power-enterprise/camcon

either of those should give you some external VCT control

it would probably be easier, cheaper and more reliable to use an ECU that supports VCT out of the box

Yeah they are fairly expensive ways to do it thats the only problem, for the same money i can pretty much do the cams. Yeah i agree that a ECU that supports VCT would be great but at the time a Power FC was hard to find and i went the Microtech route and im happy with the choice, other then the VCT problem lol.

have you brought the cams yet? if not, dont - try the car without the cams

its a big capital outlay and you find its for zero to minor gains

much like a front plenum change - zero to almost zero gains for $1000 ish

Nah dont have cams yet. There are a lot of people on here that are against cams and i dont understand why? Obviously the power difference isn't going to be huge but for $800 odd dollars for Poncams to gain power throughout the rev range i reckon its worth it. (I know a few cars that have done cams and none of those people regret doing them saying that there was no difference in power in the revs, maybe not top end power but down low definetely).

EDIT: Microtech can in fact run the VCT through the aux rpm output as stated above by Adriano, there is an aux rpm on and a aux rpm off function it in so this can be set for the VCT!

Edited March 20, 2008 by PM-R33

[jeffworld2]

why not just leave the vct soleoid on all the time, that will give you back your low/mid but choke it a bit a high revs. if its a street car, i would consider it

[Cubes]

Microtech has a plugin ecu for the r33 that supports vct.

The plugin is essentialy just the loom plug and base map.

Usually with the microtechs they enable the vct at around 1300rpm then flick it off at ~4800rpm.