GM Gen IV VVT Performance Gains
05-15-2007, 04:19 PM
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GM Gen IV VVT Dyno Data Since its release, the benefits of GM Gen IV Variable Valve Timing (VVT) technology have been unknown to the performance aftermarket. Mast Motorsports recently conducted testing during the development of our L92 turnkey crate engine package to determine the performance gains of the GM Gen IV cam phasing capabilities. We would like to share these results publicly as we develop this technology for aftermarket applications. The test engine was a stock L92 with a L76 intake manifold package, 90mm drive-by-wire throttle body, 1-3/4 inch primary long tube headers, and 87 octane fuel on our SuperFlow SF-902 NSCR engineering grade dyno. The same stock camshaft was used in all tests shown below. The tests shown below were all performed with the same calibration; therefore, the tests with a stationary cam were slightly rich in places due to the inherent lower VE of no variable valve timing. However, the differences in the engine performance are still valid for illustrating the drastic gains that can be made using VVT.
The data in the graphs below compares the performance of the camshaft in a stationary position to the performance of our crate engine package calibration which phases the camshaft throughout the RPM range. The first graph shows the performance of the camshaft phased at -5 degrees (the camshaft position to produce peak torque on our calibration). This data is laid over our power curve and highlights the gains made in the upper RPM range due to VVT.
The second graph shows the performance of the camshaft phased at -18 degrees (the camshaft position to produce peak power on our calibration). This data is laid over our power curve and highlights the gains made in the lower RPM range due to VVT.
Since the GM Gen IV engines have been released, the relevance of VVT on LS series performance applications has been unknown. As you can see, the data speaks for itself. Phasing the camshaft produces more area under the power curve throughout the entire RPM range compared to a camshaft with a stationary installed center line. We are going to continue to conducting testing while finishing the development of our Phaser Series camshafts which are designed around VVT technology. In the coming weeks we will be developing our LSX block based VVT 454X engine. We are expecting some very solid numbers with these cams and VVT and are excited about bringing this technology to the aftermarket with our crate engine packages using our M-90 ECM.
Shaun
Mast Motorsports
www.mastmotorsports.com
The data in the graphs below compares the performance of the camshaft in a stationary position to the performance of our crate engine package calibration which phases the camshaft throughout the RPM range. The first graph shows the performance of the camshaft phased at -5 degrees (the camshaft position to produce peak torque on our calibration). This data is laid over our power curve and highlights the gains made in the upper RPM range due to VVT.
The second graph shows the performance of the camshaft phased at -18 degrees (the camshaft position to produce peak power on our calibration). This data is laid over our power curve and highlights the gains made in the lower RPM range due to VVT.
Since the GM Gen IV engines have been released, the relevance of VVT on LS series performance applications has been unknown. As you can see, the data speaks for itself. Phasing the camshaft produces more area under the power curve throughout the entire RPM range compared to a camshaft with a stationary installed center line. We are going to continue to conducting testing while finishing the development of our Phaser Series camshafts which are designed around VVT technology. In the coming weeks we will be developing our LSX block based VVT 454X engine. We are expecting some very solid numbers with these cams and VVT and are excited about bringing this technology to the aftermarket with our crate engine packages using our M-90 ECM.
Shaun
Mast Motorsports
www.mastmotorsports.com
Last edited by MastMotorsports; 05-15-2007 at 04:51 PM.
05-15-2007, 04:38 PM
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This is promising stuff Shaun. The upcoming Viper will have VVT from the factory (exhaust side only) so big cube motors are finally going that direction. When you think of what the Japanese can do with smaller displacement engines because of VVT, just think of what can be done with 6+ liters and still maintain every day driveability.
05-15-2007, 07:37 PM
#4
So as RPM builds, you're gradually retarding the cam ICL, correct? This results in a later IVC, and better cylinder filling at high rpm?
But at the same time, EVO is getting later, which doesn't exactly help your cause at high RPM. Really, we need separate intake and exhaust cams for this technology to show itself to the optimum ... but it's still very useful with just a single cam.
But at the same time, EVO is getting later, which doesn't exactly help your cause at high RPM. Really, we need separate intake and exhaust cams for this technology to show itself to the optimum ... but it's still very useful with just a single cam.
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05-15-2007, 11:25 PM
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MastMotorsports, you are in nac? man if i would have known this. i go to SFA and got the hook up with ag shop and custom machine shop there. you should have called me up. i would have loved to be in on this. dude i might know who you are hook it up man.
this data is great.
this data is great.
05-16-2007, 01:34 AM
#9
great work guys!
everyone has a go at the honda guys but they have moved the game on! its clear to see the benifits of what can be achived. but nice to see some comparisions with bigger cams in there.
Chris.
everyone has a go at the honda guys but they have moved the game on! its clear to see the benifits of what can be achived. but nice to see some comparisions with bigger cams in there.
Chris.
05-16-2007, 06:45 AM
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Question In the ECU for the VVT motors can you set the injector pulse to follow the VVT settings.
IE if you retard the cam can you delay the start point of the injector pulse and delay the stop point.
This would work best for vehicles that have LT where the cat's do not need raw fuel to keep them cool (ls2's Dump Fuel at Cut Off).
I figure you can get the gas mileage to increase a little if you can keep the injector pulse set to start at the closing of the exhaust valve and injector pulse stop point to just before the intake valve closes.
An Idea for your testing...
Start the motor with the camshaft phased at -18 degrees (max low end torque setting). Set the ECU to adjust the cam just prior to the peak torque level to retard to say -15 then -12 then -9 then -5 at 500 rpm intervals or so.
I'll have to look at your torque curves when I get home (blocked at work via proxy server).
My idea is to draw out the torque's peak through about 1500rpm.... Instead of having the torque curve shoot up then fall off (non vvt motor). Have it shoot up then flatten out.
I'll look at the graphs when I get home.
IE if you retard the cam can you delay the start point of the injector pulse and delay the stop point.
This would work best for vehicles that have LT where the cat's do not need raw fuel to keep them cool (ls2's Dump Fuel at Cut Off).
I figure you can get the gas mileage to increase a little if you can keep the injector pulse set to start at the closing of the exhaust valve and injector pulse stop point to just before the intake valve closes.
An Idea for your testing...
Start the motor with the camshaft phased at -18 degrees (max low end torque setting). Set the ECU to adjust the cam just prior to the peak torque level to retard to say -15 then -12 then -9 then -5 at 500 rpm intervals or so.
I'll have to look at your torque curves when I get home (blocked at work via proxy server).
My idea is to draw out the torque's peak through about 1500rpm.... Instead of having the torque curve shoot up then fall off (non vvt motor). Have it shoot up then flatten out.
I'll look at the graphs when I get home.
05-18-2007, 10:59 AM
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Correct, we do retard the cam as RPM builds. Here is the power curve for 93 octane fuel. Also thought that I should mention that the stock cam is only .500 lift, so our L92 HO should be interesting.
Shaun
www.mastmotorsports.com
Shaun
www.mastmotorsports.com
Last edited by MastMotorsports; 05-18-2007 at 11:13 AM.
06-24-2007, 06:44 PM
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Shaun,
What WOT spark timing are you running the stock L92 at with 87 octane and VVT active? With 93 octane? Thanks for sharing your results with us on your VVT developements.
Ron
What WOT spark timing are you running the stock L92 at with 87 octane and VVT active? With 93 octane? Thanks for sharing your results with us on your VVT developements.
Ron
06-27-2007, 10:51 AM
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Originally Posted by Quick Double Nickel
Will the VVT work on a Gen III (i.e. retrofit), or is just available for Gen IV motors?
The LSX block based 454X VVT is done and we are developing the VVT for this application on the dyno. No numbers yet, but coming soon.
Shaun
www.mastmotorsports.com