GT Motorsports Turbo and NA/SC Spec Camshafts
#42
![Default](https://my350z.com/forum/images/icons/icon1.gif)
Originally Posted by Sam@GTM
We are in the process of designing our site, so please bear with us. Until then, we will make the introduction of our products here.
Now: GT Motorsports® Camshafts
Our cams have gone through a lengthy and careful design process. We will be offering two different designs (both for the non-revup 2003-2004 model year cars for the time being; the latter design is currently in development).
1. GT Motorsports® Turbo Spec camshafts for the VQ35DE
2. GT Motorsports® Stage I NA/Supercharger camshafts for the VQ35DE
GT Motorsports® Turbo Spec camshafts for the VQ35DE
The GTM® Turbo Spec cams were designed by taking a complex set of variables into account. Turbocharger compressor maps and the flow characteristics of the VQ35DE were integral in developing the cam profile. The very specifications that were attained (following several revisions and countless computerized simulation trials) allow for the maximum possible volumetric efficiency over the broadest possible rpm range. Given the high exhaust manifold pressures (that exceed intake/boost pressures) found on turbocharged systems, volumetric efficiency, aside from duration/lift, is also dependent on internal exhaust gas recirculation, which is a function of intake/exhaust cam overlap. The specifications below minimize that overlap, while retaining the highest practical cam duration, to yield the highest possible performance.
Specifications
Intake: 256 deg (stock 238)
Exhaust: 264 deg (stock 240)
Lift: 0.423” (intake and exhaust)
Overlap: 18 deg (at 0.045” lift) – less than stock
GT Motorsports® Stage I NA/Supercharger Spec camshafts for the VQ35DEThe challenges of designing NA cams are much different from turbo cams. Much greater emphasis was placed on intake resonance, which has proportionally greater effect on performance than on turbocharged vehicles. Our research showed that to maximize volumetric efficiency, an asymmetrical lift for intake and exhaust was required, in addition to the asymmetrical cam duration. It was also found that a higher lift on the intake side paired with a slightly lower exhaust side lift, achieved the greatest performance gain on the broadest possible rpm range. Higher overlap in this case is possible, as reversion is not as much of an issue.
Specifications
Intake: 264 deg (stock 238)
Exhaust: 256 deg (stock 240)
Lift: 0.435” (intake) and 0.423” (exhaust)
Overlap: 22 deg (at 0.045” lift) – more than stock
Note: the cams are cut from chill cast billet (same as the OEM Nissan camshafts) and ground on factory centerline for perfect precision.
Availability:
Now
Prices:
1. GT Motorsports® Turbo Spec camshafts for the VQ35DE: $1165 (MSRP)
2. GT Motorsports® Stage I NA/Supercharger Spec camshafts for the VQ35DE: $1165 (MSRP)
Thank you.
Next: GT Motorsports® 6MT chromoly billet gears
Now: GT Motorsports® Camshafts
Our cams have gone through a lengthy and careful design process. We will be offering two different designs (both for the non-revup 2003-2004 model year cars for the time being; the latter design is currently in development).
1. GT Motorsports® Turbo Spec camshafts for the VQ35DE
2. GT Motorsports® Stage I NA/Supercharger camshafts for the VQ35DE
GT Motorsports® Turbo Spec camshafts for the VQ35DE
The GTM® Turbo Spec cams were designed by taking a complex set of variables into account. Turbocharger compressor maps and the flow characteristics of the VQ35DE were integral in developing the cam profile. The very specifications that were attained (following several revisions and countless computerized simulation trials) allow for the maximum possible volumetric efficiency over the broadest possible rpm range. Given the high exhaust manifold pressures (that exceed intake/boost pressures) found on turbocharged systems, volumetric efficiency, aside from duration/lift, is also dependent on internal exhaust gas recirculation, which is a function of intake/exhaust cam overlap. The specifications below minimize that overlap, while retaining the highest practical cam duration, to yield the highest possible performance.
Specifications
Intake: 256 deg (stock 238)
Exhaust: 264 deg (stock 240)
Lift: 0.423” (intake and exhaust)
Overlap: 18 deg (at 0.045” lift) – less than stock
GT Motorsports® Stage I NA/Supercharger Spec camshafts for the VQ35DEThe challenges of designing NA cams are much different from turbo cams. Much greater emphasis was placed on intake resonance, which has proportionally greater effect on performance than on turbocharged vehicles. Our research showed that to maximize volumetric efficiency, an asymmetrical lift for intake and exhaust was required, in addition to the asymmetrical cam duration. It was also found that a higher lift on the intake side paired with a slightly lower exhaust side lift, achieved the greatest performance gain on the broadest possible rpm range. Higher overlap in this case is possible, as reversion is not as much of an issue.
Specifications
Intake: 264 deg (stock 238)
Exhaust: 256 deg (stock 240)
Lift: 0.435” (intake) and 0.423” (exhaust)
Overlap: 22 deg (at 0.045” lift) – more than stock
Note: the cams are cut from chill cast billet (same as the OEM Nissan camshafts) and ground on factory centerline for perfect precision.
Availability:
Now
Prices:
1. GT Motorsports® Turbo Spec camshafts for the VQ35DE: $1165 (MSRP)
2. GT Motorsports® Stage I NA/Supercharger Spec camshafts for the VQ35DE: $1165 (MSRP)
Thank you.
Next: GT Motorsports® 6MT chromoly billet gears
The specs of both the Inlet & Exhaust cams show a larger duration than stock. (I am assuming that these comparison durations are measured at the same lift)
As the exhaust cam is fixed (no VTC) the stock ex cam has a closing position of 8 deg ATDC, your cam has 24 deg more duration so the closing position of your cam will be aprox 20 deg ATDC.
The stock Inlet cam has a static opening position of -6 deg BTDC (that is 6 deg ATDC) Your inlet cam has 18 deg more duration than stock & in the static postion your cam would open aprox 3 deg BTDC.
Last edited by Nathan; 12-02-2006 at 12:18 AM.
#43
![Default](https://my350z.com/forum/images/icons/icon1.gif)
You can manufacture the cam to move the entire profile forward/backward (which retards/advances it's opening for the exhaust cam, opposite for the intake cam) relative to it's position markers (located on the aft plate). So yes, you do have longer duration, but it extends more into the intake/exuast strokes then the stock cams do, hence less overlap. This would be akin to having an adjustable cam sproket like they do on so many cars. THe VVT can't compensate, since it can only go by the cam position gaps on the signal plate of the cam, which are in an unchanged position.
#44
![Default](https://my350z.com/forum/images/icons/icon1.gif)
Originally Posted by GurgenPB
You can manufacture the cam to move the entire profile forward/backward (which retards/advances it's opening for the exhaust cam, opposite for the intake cam) relative to it's position markers (located on the aft plate). So yes, you do have longer duration, but it extends more into the intake/exuast strokes then the stock cams do, hence less overlap. This would be akin to having an adjustable cam sproket like they do on so many cars. THe VVT can't compensate, since it can only go by the cam position gaps on the signal plate of the cam, which are in an unchanged position.
The stock cams only have 2 deg of overlap ( Ex 8 ATDC In 6 ATDC ) at there advertised duration which is measured @ aprox .010" lift.
GTM cams @ .045" lift are 18 deg overlap. This figure would be much higher @ .010". So how is 18 deg at best, less than 2 deg
#45
![Default](https://my350z.com/forum/images/icons/icon1.gif)
Originally Posted by Nathan
This is not a critisism of your camshafts but there is no known way that your turbo spec camshafts have less overlap than stock.
The specs of both the Inlet & Exhaust cams show a larger duration than stock. (I am assuming that these comparison durations are measured at the same lift)
As the exhaust cam is fixed (no VTC) the stock ex cam has a closing position of 8 deg ATDC, your cam has 24 deg more duration so the closing position of your cam will be aprox 20 deg ATDC.
The stock Inlet cam has a static opening position of -6 deg BTDC (that is 6 deg ATDC) Your inlet cam has 18 deg more duration than stock & in the static postion your cam would open aprox 3 deg BTDC.
The specs of both the Inlet & Exhaust cams show a larger duration than stock. (I am assuming that these comparison durations are measured at the same lift)
As the exhaust cam is fixed (no VTC) the stock ex cam has a closing position of 8 deg ATDC, your cam has 24 deg more duration so the closing position of your cam will be aprox 20 deg ATDC.
The stock Inlet cam has a static opening position of -6 deg BTDC (that is 6 deg ATDC) Your inlet cam has 18 deg more duration than stock & in the static postion your cam would open aprox 3 deg BTDC.
#47
![Default](https://my350z.com/forum/images/icons/icon1.gif)
Originally Posted by BrianLG35C
Any details on their head packages yet?![Confused](https://my350z.com/forum/images/smilies/confused.gif)
![Confused](https://my350z.com/forum/images/smilies/confused.gif)
#50
Registered User
iTrader: (6)
Join Date: Jul 2006
Location: Seattle.
Posts: 2,634
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://my350z.com/forum/images/icons/icon1.gif)
So these cams will increase my top end with no sacrifice of low/mid end power I presume?
I'm a newbie with camshafts so if someone please explain to me the full benefits of the Turbo spec Cams. They are something really affordable for me at this time so this might just be the next performance mod I make.
I'm a newbie with camshafts so if someone please explain to me the full benefits of the Turbo spec Cams. They are something really affordable for me at this time so this might just be the next performance mod I make.
#51
New Member
iTrader: (51)
![Default](https://my350z.com/forum/images/icons/icon1.gif)
I installed the turbo cams and they are hot cams with the Greddy TT. The short overlap adds alot of meat to the powerband. It idles like stock. No one would ever know that they were instaleld by listening to the car idle. Definetly worth the money along with the JWT springs and retainers. Besides the Greddy TT kit this is the best mod I have done no question.
JET
JET
#55
Registered User
iTrader: (8)
![Default](https://my350z.com/forum/images/icons/icon1.gif)
I am curious to hear the response from GTM regarding less overlap on the turbo cams. It says that all cams are ground on the factory centerlines.....that being true.....how can you have less overlap than the stock cams? if you shifted the centerline, it would be possible.....
please enlighten us GTM...................................
please enlighten us GTM...................................
Thread
Thread Starter
Forum
Replies
Last Post