Worth swapping to a different vvt cam?
Looking at hicksport's dyno sheet below for his VVT-2 LY6, there is about a 60ft-lb (roughly 20%) rise in torque between 3,100 and about 3,700rpm. Below that the dyno isn't clear. That may be the jump you're feeling. If you look further down, I also posted TSP's L99 results. It seems to have about a 40ft-lb rise in the same area, roughly a 12% increase in that case. The jump is probably a bit less in the L99 case due to the increased compression ratio. In both cases, the flattest range of the torque curve seems to be from around 3,700rpm up to around 6,000rpm. I think if you want more power down low you'll want a smaller cam or a cam with more lobe separation, but you are probably going to give up some power at the top end. For example, take a look at futureuser's results with a vengence stage2 nonVVT cam here. Looking between 5,000-6,000rpm, his torque curve starts to drop off whereas the VVT-2 stays steady, but on the bottom end he has more torque over a pretty broad range from around 2,800 to maybe 3,500 or so. His cam is similar in lift & duration to the VVT2, but has a wider LSA and possibly a different lobe profile. Keep in mind he's going through an auto tranny.
hicksport LY6 VVT-2 w/ manual tranny
TSP L99 w/ auto tranny
I look forward to seeing what you get after a tune. You may want to have the tuner focus on that range from say 2,500-3,500 to see if they can make improvements with cam timing. Unfortunately I'm not sure if closing the intake sooner is going to save you from the valve overlap at those RPMs.
hicksport LY6 VVT-2 w/ manual tranny
TSP L99 w/ auto tranny
I look forward to seeing what you get after a tune. You may want to have the tuner focus on that range from say 2,500-3,500 to see if they can make improvements with cam timing. Unfortunately I'm not sure if closing the intake sooner is going to save you from the valve overlap at those RPMs.
futureuser, I digitized your dyno curve and hicksports using Excel. You definitely have a leg up with your combo. I wonder where the difference is coming from since the cams are so similar in @050, lift, etc. Maybe the wider LSA? Or all in the tune? It looks like the VVT-2 uses LSL lobes. I wonder if Vengence is using LSKs or some other lobe.
I'll have to look into the type of lobes. I thought wider lobe separation had a tendency for smoother idle, more top end power and less bottom end torque? I'll look into the type of lobes. With the latest tune I have slightly more horsepower and about the same torque. The run with the converter locked has a spike, so the 433 torque is not accurate. But it's amazing what a good converter can do. I traded 16 hp for 67 lb/ft of torque and can still lock up the converter in the top end if I want to get back the lost hp.
I had two different tuners tune my car. 1 used hp tuners and 1 used efi live. The results were about the same with the later picking up 9hp. But my lighter weight converter and the engine breaking in a little more may have had something to do with it. I got a full complimentary re-tune because hp tuners locked us out of the van program with no solution in sight.
I had two different tuners tune my car. 1 used hp tuners and 1 used efi live. The results were about the same with the later picking up 9hp. But my lighter weight converter and the engine breaking in a little more may have had something to do with it. I got a full complimentary re-tune because hp tuners locked us out of the van program with no solution in sight.
futureuser, I think wider lobe separation favors lower RPM output due to reduced overlap. That last dyno you posted has a wild early torque peak and a completely different shape from your first dyno run. Where is all that early torque coming from? Here's the original for reference.
Maybe I'm wrong, but my understanding has been that wider LSAs are better for high rpm power and tighter LSAs make better throttle response and more torque. I'm pretty sure the wider LSA's favor forced induction and Nitrous as well. I was surprised to get a nearly 8/10 drop in ET with just a 90 shot of nitrous for my 11.01@ 123 run.
Here is a reference article:
http://www.popularhotrodding.com/eng...s/viewall.html
The latest graph I posted is much harder to read than the first. There are two runs on the graph. One has the converter locked (blue lines) and one has it unlocked (red lines). The locked run has a spike when the throttle is nailed (at a higher rpm) and shows the spike early in the run. This spike has to be disregarded and the rest of the run matches the original torque curve. The run with the converter unlocked looks nothing like the other. The converter multiplies the torque at lower rpm and I get less peak power.
In the original run, the converter is stock and locked. The new graph shows the new fti converter unlocked and locked, and the massive torque at low rpm which explains my huge ET drop when I swapped converters. I don't have the low rpm documentation of this new locked run, like the original, but it it clear I make a few more pounds of torque.
Also, I forgot to mention I did a little porting of my stock LY6 throttle body, which may account for a little of my new found power. I have run on the old tune with the ported throttle body but have yet to run on the new tune. I expect the booger to be quicker.
Here is a reference article:
http://www.popularhotrodding.com/eng...s/viewall.html
The latest graph I posted is much harder to read than the first. There are two runs on the graph. One has the converter locked (blue lines) and one has it unlocked (red lines). The locked run has a spike when the throttle is nailed (at a higher rpm) and shows the spike early in the run. This spike has to be disregarded and the rest of the run matches the original torque curve. The run with the converter unlocked looks nothing like the other. The converter multiplies the torque at lower rpm and I get less peak power.
In the original run, the converter is stock and locked. The new graph shows the new fti converter unlocked and locked, and the massive torque at low rpm which explains my huge ET drop when I swapped converters. I don't have the low rpm documentation of this new locked run, like the original, but it it clear I make a few more pounds of torque.
Also, I forgot to mention I did a little porting of my stock LY6 throttle body, which may account for a little of my new found power. I have run on the old tune with the ported throttle body but have yet to run on the new tune. I expect the booger to be quicker.
Last edited by futureuser; Jul 21, 2012 at 12:26 AM.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Thread Starter
Joined: Dec 2007
Posts: 734
Likes: 0
From: Rittman, Ohio
Ill be running on a mustang dyno on monday and continue being tuned via hptuners ( they're actually going to use my hptuners cable and module to save from having to buy credits and therefore saving me money). My truck weighs 3850 with me in it.
Last edited by tiresmokinV8; Jul 21, 2012 at 12:50 AM.
Teching In
Joined: Nov 2010
Posts: 14
Likes: 0
From: Largo, Fl
not to hijack the thread..but while youre talking about a LY6 vvt cam swap and the phaser I have a question...I sent my build sheet to Pat G for a custom VVT cam for my ly6 out of a 2007.5 2500hd. When I was talking to Comp they said I HAVE to know which phaser I have and something about the bolts or how many there are on the cam. Does anyone know what phaser/bolt style this year ly6 motor has( its a non afm/dod/flexfuel motor)?
Why did they change em? Can I run the oem or is a MUST change item? Im trying to get all this together along with the cam(something in vvt form of a tr224) and springs to match along with pushrods too and then have it tuned by Tampa tuning(Phil'sC5vette)... I wanna do it right the first time. Thanks and great thread btw!!
Why did they change em? Can I run the oem or is a MUST change item? Im trying to get all this together along with the cam(something in vvt form of a tr224) and springs to match along with pushrods too and then have it tuned by Tampa tuning(Phil'sC5vette)... I wanna do it right the first time. Thanks and great thread btw!!
not to hijack the thread..but while youre talking about a LY6 vvt cam swap and the phaser I have a question...I sent my build sheet to Pat G for a custom VVT cam for my ly6 out of a 2007.5 2500hd. When I was talking to Comp they said I HAVE to know which phaser I have and something about the bolts or how many there are on the cam. Does anyone know what phaser/bolt style this year ly6 motor has( its a non afm/dod/flexfuel motor)?
Phaser # 12585994 uses Comp limiter kit #5456, 156 core
Phaser # 12606358 uses Comp limiter kit #5460, 189 core
To get to your phaser part number, you can remove the water pump and VVT magnet. If you look at the second picture below you can see my phaser part number etched near the top left ending in 358.
Teching In
Joined: Nov 2010
Posts: 14
Likes: 0
From: Largo, Fl
Damn..so i gotta tear apart my motor to get the correct cam phaser? that sucks. Comp said I can find the correct one by VIN. What do you think. My plan was to stockpile all the parts then do the install when im ready. Its my DD, so tearing it down and waiting is not good news..
Last edited by quicksr20; Jul 23, 2012 at 05:00 PM.
Thread Starter
Joined: Dec 2007
Posts: 734
Likes: 0
From: Rittman, Ohio
Looks like you just have to remove the waterpump and then the phaser piston cover to check.
Trucks at the tuners. They are backed up from a problem vehicle so wont be tuning mine for another hour or two. I work 3rd shift so I wont be able to watch plus its 45mins away so ll let you know what she puts down whenever I find out. My buddy said hell try to make it there and get a vid.
Trucks at the tuners. They are backed up from a problem vehicle so wont be tuning mine for another hour or two. I work 3rd shift so I wont be able to watch plus its 45mins away so ll let you know what she puts down whenever I find out. My buddy said hell try to make it there and get a vid.
Thread Starter
Joined: Dec 2007
Posts: 734
Likes: 0
From: Rittman, Ohio
Buddy of mine is at the tuners since he lives close to it and is good friends with the owners. Says it looks like they wont get to my truck today either. But they will take a vid when they do.