what cams should i run with a gt-35r setup??
If you want smoother idle, you want to reduce overlap as much as possible.. HKS272's are likely the best cam for the turbo, but you will not get smooth idle with them.
So onto a higher lift cam with slightly shorter duration with less overlap.. Probably the JUN or Tomei's But keep in mind that you'll likely need new valvesprings and retainers for anything thats a higher than stock lift.
I haven't seen anything on the revolvers, and haven't heard any review of the Comp Cam's yet.. but you might want to look into the comp cam profiles and see if there's something with a duration shorter than the 272's, but higher lift closer to the tomei's race cam profile.
There's alot more science to this, since the ramp of the cam profile also has an affect on idle quality, emissions, and obviously performance.
So onto a higher lift cam with slightly shorter duration with less overlap.. Probably the JUN or Tomei's But keep in mind that you'll likely need new valvesprings and retainers for anything thats a higher than stock lift.
I haven't seen anything on the revolvers, and haven't heard any review of the Comp Cam's yet.. but you might want to look into the comp cam profiles and see if there's something with a duration shorter than the 272's, but higher lift closer to the tomei's race cam profile.
There's alot more science to this, since the ramp of the cam profile also has an affect on idle quality, emissions, and obviously performance.
interesting. Are there ways to get the car to idle with hks 272/272 with UTEC?? Or is it a hassle. The procams do require springs but are only 260/260. would the Tomei's be enough of a step forward?? I dont know what to do..... RRR
Either the UTEC or Dynoflash are capable of helping your idle, but not every car responds to the idle adjustments the same way.. Generally 272 cams means you'll have to raise your idle somewhat to keep the airflow through the MAF sensor at a level that low engine vacuum doesnt cause the idle to surge up and down...
You can also reduce the overlap of your cams with cam gears -4/-1 which should help idle. There's other idle tricks out there, but a idle flash may do a better job at it until the UTEC gets its idle tuning features (idle speed, compensation, etc.)
Generally to get a smoother idle, you have to boost your engine vacuum, so reducing cam overlap, increasing idle speed, and making some timing or fuel adjustments are your typical steps.
I think you'll have to talk to some of the guys running the GT35r and see, I suspect most of them are not concerned about drivability or idle quality, and/or are running a standalone. You have to find someone who is running the turbo and cams, and still has a stock ECU and a piggyback or reflash to see what he had done.
No pun intended, but your mileage may vary.. It turns out its a little more difficult to get a decent idle if you live in a climate that changes where it might be alot easier in other locations.
You can also reduce the overlap of your cams with cam gears -4/-1 which should help idle. There's other idle tricks out there, but a idle flash may do a better job at it until the UTEC gets its idle tuning features (idle speed, compensation, etc.)
Generally to get a smoother idle, you have to boost your engine vacuum, so reducing cam overlap, increasing idle speed, and making some timing or fuel adjustments are your typical steps.
I think you'll have to talk to some of the guys running the GT35r and see, I suspect most of them are not concerned about drivability or idle quality, and/or are running a standalone. You have to find someone who is running the turbo and cams, and still has a stock ECU and a piggyback or reflash to see what he had done.
No pun intended, but your mileage may vary.. It turns out its a little more difficult to get a decent idle if you live in a climate that changes where it might be alot easier in other locations.
Ime thinking that a higher lift cam will allow more air into the cylinders. So lets say i go high lift short duration. Tomei 11.5mm @260/260. Wont a longer duration shorter lift flow about the same amount of air?? (HKS 272/272). It seems like opening a valve higher but a shorter amount of time would yield the same as opening the valve shorter but longer. Where are all the GT 35 users out there??? RRR
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I don’t claim to be a pro on cams in any way so this will be what I’ve picked up reading and asking people who seam to know their business. If you disagree please feel free to express that and why. 
In general the cams need to be a good match to the size of your turbo in terms of what rpm range the turbo and the cams are most efficient. The longer the duration on the cams the higher in the rpm range the power is moved, the same goes for the size of the turbo. A GT35 is a fairly large turbo for a 2L engine so it should be capable of supplying air well up in the 9k rpm range. A turbo typically has a 3-4k rpm range where it’s really efficient, if you look at the stock turbo I would say that range is from just before 3k and up to 6 maybe 6,5k and then it runs out of puff. If you look at a GT35R that would move that efficiency up from maybe 4,5-5k up to around 9k given the same engine displacement.
When I was looking for cams for my 3071 I asked Simon Norris at Norris Designs what cams he would suggest to be a good match to that turbo. He then explained about what I’ve said above and that I should be looking for a cam that has fairly low duration since the 3071 would become efficient from about 3,5k up to maybe 8-8,5k. Higher lift would also be a factor to take into calculation but it’s not that dependant on the rpms as the duration seam to be. If you are not going to extremes higher lift is always good.
But, lots of people gain good results putting for example HKS 272’s on together with the stock turbo, which maybe says something about the lift and profiles of the HKS cam lobes.
In general it seam as if Tomei, JUN, Piper and such cams are the choise if you like higher lift and more aggressive lobe profiles. As a matter of fact I think I read that the guy who designed the Tomei Pro Cams now work for Piper so those two should probably be very similar in design.
I also know that Tomei now offer their Pro series with 11,5mm lift in 270 as well as 280 degrees for the 4G63. Might be a bit hard to get a hold of though with long delivery time as I’ve heard.
In general the cams need to be a good match to the size of your turbo in terms of what rpm range the turbo and the cams are most efficient. The longer the duration on the cams the higher in the rpm range the power is moved, the same goes for the size of the turbo. A GT35 is a fairly large turbo for a 2L engine so it should be capable of supplying air well up in the 9k rpm range. A turbo typically has a 3-4k rpm range where it’s really efficient, if you look at the stock turbo I would say that range is from just before 3k and up to 6 maybe 6,5k and then it runs out of puff. If you look at a GT35R that would move that efficiency up from maybe 4,5-5k up to around 9k given the same engine displacement.
When I was looking for cams for my 3071 I asked Simon Norris at Norris Designs what cams he would suggest to be a good match to that turbo. He then explained about what I’ve said above and that I should be looking for a cam that has fairly low duration since the 3071 would become efficient from about 3,5k up to maybe 8-8,5k. Higher lift would also be a factor to take into calculation but it’s not that dependant on the rpms as the duration seam to be. If you are not going to extremes higher lift is always good.
But, lots of people gain good results putting for example HKS 272’s on together with the stock turbo, which maybe says something about the lift and profiles of the HKS cam lobes.
In general it seam as if Tomei, JUN, Piper and such cams are the choise if you like higher lift and more aggressive lobe profiles. As a matter of fact I think I read that the guy who designed the Tomei Pro Cams now work for Piper so those two should probably be very similar in design.
I also know that Tomei now offer their Pro series with 11,5mm lift in 270 as well as 280 degrees for the 4G63. Might be a bit hard to get a hold of though with long delivery time as I’ve heard.
Last edited by EVOVII_SWE; Dec 20, 2004 at 12:55 AM.
First of all, the duration numbers you are quoting are 'advertised' duration. Don't assume that the Tomei 260s feature less duration because we don't know the effective duration specs (e.g. 1mm).
If you want to use the HKS 272 cams (which are proven performers), and you want a butter smooth idle, you can achieve this via a set of adjustable cam gears. Simply set the exhaust cam ~3 degrees (as per the cam gears) advanced with respect to the intake cam. The idle will be no different than a stocker.
If you want to use the HKS 272 cams (which are proven performers), and you want a butter smooth idle, you can achieve this via a set of adjustable cam gears. Simply set the exhaust cam ~3 degrees (as per the cam gears) advanced with respect to the intake cam. The idle will be no different than a stocker.
Originally Posted by Ted B
First of all, the duration numbers you are quoting are 'advertised' duration. Don't assume that the Tomei 260s feature less duration because we don't know the effective duration specs (e.g. 1mm).
If you want to use the HKS 272 cams (which are proven performers), and you want a butter smooth idle, you can achieve this via a set of adjustable cam gears. Simply set the exhaust cam ~3 degrees (as per the cam gears) advanced with respect to the intake cam. The idle will be no different than a stocker.
If you want to use the HKS 272 cams (which are proven performers), and you want a butter smooth idle, you can achieve this via a set of adjustable cam gears. Simply set the exhaust cam ~3 degrees (as per the cam gears) advanced with respect to the intake cam. The idle will be no different than a stocker.
SO you are saying to only advance the exhaust side 3% and leave the intake side alone. Is this how you run your setup? I have been running the -4I -1 E with great results. I know you dyno tested your car with different results, but what setting did you end up with?
The single most important cam timing event is the point where the intake valve closes. Advancing or retarding the intake cam is going to have the most profound effect on where the torque peak falls. The exhaust cam setting is going to essentially influence idle characteristics and spool timing.
As compared to a -3/-3 setting, the -4/-1 setting for the HKS 272s will give a few more peak hp at the expense of ~200rpm later spool. I'm using the -3/-3 setting because I like the slightly quicker spool, but it's really just personal preference as to which setting you choose.
As compared to a -3/-3 setting, the -4/-1 setting for the HKS 272s will give a few more peak hp at the expense of ~200rpm later spool. I'm using the -3/-3 setting because I like the slightly quicker spool, but it's really just personal preference as to which setting you choose.
I run the GT35r kit form AMS. I use the stock ECU as the only tunning tool, flashed of course. I also run straight 272's combo. The idle is perfect and the driveability is stock like. I wouldn't settle for anything less than a true streetable Big Turbo Evo. In fact this is the main reason why I chose to refrain from a piggy back or standalone, there's just nothing like a stock ECU. The latest Dynoflash is unreal with tunning for a stock like idle and zero concerns. There is no sense in going with a smaller than 272 combo with such a big turbo, its going against the grain on a turbo that only shines in the mid to high rpm range.
Gil-superz
Gil-superz
Originally Posted by Ted B
First of all, the duration numbers you are quoting are 'advertised' duration. Don't assume that the Tomei 260s feature less duration because we don't know the effective duration specs (e.g. 1mm).
If you want to use the HKS 272 cams (which are proven performers), and you want a butter smooth idle, you can achieve this via a set of adjustable cam gears. Simply set the exhaust cam ~3 degrees (as per the cam gears) advanced with respect to the intake cam. The idle will be no different than a stocker.
If you want to use the HKS 272 cams (which are proven performers), and you want a butter smooth idle, you can achieve this via a set of adjustable cam gears. Simply set the exhaust cam ~3 degrees (as per the cam gears) advanced with respect to the intake cam. The idle will be no different than a stocker.
As to what cams to choose I would strongly recomend the HKS 272/272 or the Jun Cams. both make great power and really wake that turbo up.
Eric
