L92 DOD and VVT elimination..Why?
Thread Starter
Teching In
Joined: Jun 2008
Posts: 8
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From: Montana
L92 DOD and VVT elimination..Why? Just picked up this thing from a salvage yard and understand that a lot of people are not using these two features. I did a little bit of searching and could not really figure out why. I am just planning on doing a cam swap and adding headers on this thing then it's going into an A-body.
Should I keep them functional? I'm only shooting for 500-ish hp.
Thank you.
Should I keep them functional? I'm only shooting for 500-ish hp.
Thank you.
TECH Regular
Joined: Nov 2005
Posts: 459
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From: Arlington, TN
With a cam swap you'll probably take DOD out. Unless you can find a company with an aftermarket DOD (now AFM) cam.
VVT is usually dropped due to similar reasons. If you put a hot cam in with a VVT cam phaser then you could run into PVT issue's. Since the Cam phaser advances the cam in the low rpm and retards the cam in the upper rpm -vs- keeping the cam at a set point for valve events throughout the rpm range.
To be honest a performance VVT/AFM cam is needed because VVT allows for better hp and tq throughout the power band while AFM allows for better fuel economy while daily driving.
I've been an advocate of AFM/VVT performance cam's for a while, just no one listens...
VVT is usually dropped due to similar reasons. If you put a hot cam in with a VVT cam phaser then you could run into PVT issue's. Since the Cam phaser advances the cam in the low rpm and retards the cam in the upper rpm -vs- keeping the cam at a set point for valve events throughout the rpm range.
To be honest a performance VVT/AFM cam is needed because VVT allows for better hp and tq throughout the power band while AFM allows for better fuel economy while daily driving.
I've been an advocate of AFM/VVT performance cam's for a while, just no one listens...
Thread Starter
Teching In
Joined: Jun 2008
Posts: 8
Likes: 0
From: Montana
Thanks.
I know that I saw a company out there that had a cam that allowed the use of the VVT I can't remember who it was though. The AFM is not a huge deal for me I guess.
Any major economy or power losses from getting rid of them? I like the idea of keeping this a little more simple.
Thanks
I know that I saw a company out there that had a cam that allowed the use of the VVT I can't remember who it was though. The AFM is not a huge deal for me I guess.
Any major economy or power losses from getting rid of them? I like the idea of keeping this a little more simple.
Thanks
Last edited by slowmobile; Jun 29, 2008 at 10:50 AM. Reason: Added info
FormerVendor
Joined: Mar 2007
Posts: 182
Likes: 0
From: Nacogdoches, TX
Thanks.
I know that I saw a company out there that had a cam that allowed the use of the VVT I can't remember who it was though. The AFM is not a huge deal for me I guess.
Any major economy or power losses from getting rid of them? I like the idea of keeping this a little more simple.
Thanks
I know that I saw a company out there that had a cam that allowed the use of the VVT I can't remember who it was though. The AFM is not a huge deal for me I guess.
Any major economy or power losses from getting rid of them? I like the idea of keeping this a little more simple.
Thanks
To my knowledge, we are currently the only company that does VVT camshafts. We have setups that can make a stock L92 safely make up to 545HP. Unlike the factory setup, our cam timing table is set up to make peak power/torque all the way across the RPM range on our M-90 Control Systems. We don't run Active Fuel Managment (AFM) on our products.
There are major losses to be seen from removing the VVT system. The VVT greatly broadens the torque curve for a streetable, high output combination. The data in the link below shows some of the performance benefits of VVT on just a stock L92.
https://ls1tech.com/forums/showthrea...&highlight=vvt
Hope this helps!
FormerVendor
Joined: Mar 2007
Posts: 182
Likes: 0
From: Nacogdoches, TX
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TECH Fanatic
Joined: Jul 2005
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From: Beebe, Arkansas
It should work still work though. I would keep the VVT as well.
EDIT: also the fuel mileage gain from AFM is small and if you don't have the right set-up, gears tire size then it my not stay in V4 mode long if at all.
In Stock form the L92 doesn't use the AFM (dod). Everything is there, but not used. GM was having problems with the AFM tuning and the 6l80 trans used behind the L92. The L76 in the Vortec max uses the AFM and VVT but uses a 4l70 trans.
It should work still work though. I would keep the VVT as well.
EDIT: also the fuel mileage gain from AFM is small and if you don't have the right set-up, gears tire size then it my not stay in V4 mode long if at all.
It should work still work though. I would keep the VVT as well.
EDIT: also the fuel mileage gain from AFM is small and if you don't have the right set-up, gears tire size then it my not stay in V4 mode long if at all.
That's what I mean, though, there isn't a tuning option to even play with it now.
-Geoff
TECH Fanatic
Joined: Jul 2005
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From: Beebe, Arkansas
I think it depends on how you set up the DOD. I have DOD on my truck, and it only seems to go into 4 cyl mode when you are at low speeds, and goes back to 8 with any kind of load, so it must have MAP as well as speed based thresholds for cylinder deactivation. I would think that on a lighter f-body, you could tweak the MAP threshold (assuming that is one of the triggers) and get it in 4 cyl mode more often.
That's what I mean, though, there isn't a tuning option to even play with it now.
-Geoff
That's what I mean, though, there isn't a tuning option to even play with it now.
-Geoff
I think just using a 6l80 or T56 alone would be better mileage than trying to get the DOD to work. But, in a lighter car it might actually be worth it if your worried about gas. I haven't heard of anyone doing this on a swap cause most times folks want HP numbers not gas mileage numbers.
-Geoff
