LY6 Build - VVT with Carb?
04-18-2013, 06:22 PM
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LY6 Build - VVT with Carb? Hey guys, new here and I am also new to building these Gen III/Gen IV motors.
I've got a low mileage LY6 longblock that sucked in some water and damaged a rod that I just picked up for a great price. I'll be building it for a Jeep CJ7 so the plan as of right now is to get everything to the machine shop and back to an in-spec oem short long block. From there I am up in the air on going with the fuel injection (great for offroading) or going carb. My first instinct is to go carb for the ease of installation and tuning. Luckily it's not a DOD motor and has the square port L92 style heads so the HP and TQ levels I'm looking for should be pretty easy to come by.
Now on to the main point - several days ago, I ran across a build writeup where someone commented on a standalone VVT control box. I've been searching for some time trying to find this reference again, but have been unsuccessful. Has anyone on here heard of such a thing?
If not, from what I've read it isn't much to block off the VVT and run a traditional cam - I was just hoping to take advantage of the new technology and grab the extra HP under the curve!
If anyone has any "gotcha's" that are common place with a carb'd LSx build, toss them out there, I'm all ears!
Thanks in advance for any help given!
I've got a low mileage LY6 longblock that sucked in some water and damaged a rod that I just picked up for a great price. I'll be building it for a Jeep CJ7 so the plan as of right now is to get everything to the machine shop and back to an in-spec oem short long block. From there I am up in the air on going with the fuel injection (great for offroading) or going carb. My first instinct is to go carb for the ease of installation and tuning. Luckily it's not a DOD motor and has the square port L92 style heads so the HP and TQ levels I'm looking for should be pretty easy to come by.
Now on to the main point - several days ago, I ran across a build writeup where someone commented on a standalone VVT control box. I've been searching for some time trying to find this reference again, but have been unsuccessful. Has anyone on here heard of such a thing?
If not, from what I've read it isn't much to block off the VVT and run a traditional cam - I was just hoping to take advantage of the new technology and grab the extra HP under the curve!
If anyone has any "gotcha's" that are common place with a carb'd LSx build, toss them out there, I'm all ears!
Thanks in advance for any help given!
04-19-2013, 07:36 AM
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You are correct. There are some steep hills in the near future and there are some carbs that are capable of handling it. Eventually this will be a FI motor, but a carb is more friendly budget wise and effort wise. I'm not much of an electrical guy - I can do it, I would just rather be doing something else!
Carb + VVT sounds like a winning combination for getting started. I'm just not sure if it's possible...
Carb + VVT sounds like a winning combination for getting started. I'm just not sure if it's possible...
04-20-2013, 10:20 AM
#4
I would definately do a carb, unless you are going to leave the engine 100% stock and dont need to ever re-tune it, or you simply are willing to spend the $$ on efi.
On the LY6, you could just leave the vvt stuff intact if you do not want to change cams. It defaults to locked in full advance mode. this will give the engine good low speed manners, and KILL upper rpm power.
Personally I think the Square port heads are the wrong way to go for an off road vehicle. you need torque and lots of it. It would probably be less money for you to find a good running LQ4 catheral port 6.0, than to fix the broken LY6. You could sell the L92 heads and other LY6 parts and cover it I'm sure.
I did some research on trying to control the vvt without the factory computer, and the control is a pulse width modulated solenoid that controls the oil flow/pressure into the cam phaser.
The following is just my theory; but I beleive you could do it with simple 12v rpm switch. - full advance with 0v untill say 3500rpm, then full retard with +12v above that.
BUT, I also think the Factory phaser has too much travel and needs some internal limiters to keep things from getting out of hand.
On the LY6, you could just leave the vvt stuff intact if you do not want to change cams. It defaults to locked in full advance mode. this will give the engine good low speed manners, and KILL upper rpm power.
Personally I think the Square port heads are the wrong way to go for an off road vehicle. you need torque and lots of it. It would probably be less money for you to find a good running LQ4 catheral port 6.0, than to fix the broken LY6. You could sell the L92 heads and other LY6 parts and cover it I'm sure.
I did some research on trying to control the vvt without the factory computer, and the control is a pulse width modulated solenoid that controls the oil flow/pressure into the cam phaser.
The following is just my theory; but I beleive you could do it with simple 12v rpm switch. - full advance with 0v untill say 3500rpm, then full retard with +12v above that.
BUT, I also think the Factory phaser has too much travel and needs some internal limiters to keep things from getting out of hand.
04-20-2013, 03:05 PM
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I would definately do a carb, unless you are going to leave the engine 100% stock and dont need to ever re-tune it, or you simply are willing to spend the $$ on efi.
On the LY6, you could just leave the vvt stuff intact if you do not want to change cams. It defaults to locked in full advance mode. this will give the engine good low speed manners, and KILL upper rpm power.
Personally I think the Square port heads are the wrong way to go for an off road vehicle. you need torque and lots of it. It would probably be less money for you to find a good running LQ4 catheral port 6.0, than to fix the broken LY6. You could sell the L92 heads and other LY6 parts and cover it I'm sure.
I did some research on trying to control the vvt without the factory computer, and the control is a pulse width modulated solenoid that controls the oil flow/pressure into the cam phaser.
The following is just my theory; but I beleive you could do it with simple 12v rpm switch. - full advance with 0v untill say 3500rpm, then full retard with +12v above that.
BUT, I also think the Factory phaser has too much travel and needs some internal limiters to keep things from getting out of hand.
On the LY6, you could just leave the vvt stuff intact if you do not want to change cams. It defaults to locked in full advance mode. this will give the engine good low speed manners, and KILL upper rpm power.
Personally I think the Square port heads are the wrong way to go for an off road vehicle. you need torque and lots of it. It would probably be less money for you to find a good running LQ4 catheral port 6.0, than to fix the broken LY6. You could sell the L92 heads and other LY6 parts and cover it I'm sure.
I did some research on trying to control the vvt without the factory computer, and the control is a pulse width modulated solenoid that controls the oil flow/pressure into the cam phaser.
The following is just my theory; but I beleive you could do it with simple 12v rpm switch. - full advance with 0v untill say 3500rpm, then full retard with +12v above that.
BUT, I also think the Factory phaser has too much travel and needs some internal limiters to keep things from getting out of hand.
I've only got $400 wrapped up into the LY6 at this point, so I will probably stick it out. The vehicle is going to be a dual purpose and will see high RPMs on a regular basis (mud holes, Silver Lake dunes, etc.). The 5.38 gears I will be running should help with the bottom end as well.
What you've found on the standalone control is similar to how I thought it would work, I just didn't know if it was a 12v constant signal and anything as far as what limiters would be needed for the factory phaser.
There are some DIY kits out there for Mazda's VVT and I believe they run on the same concept as what you have described above. I wonder if it would be possible to buy one of these and adapt it for use on a LSx motor using VVT. As long as it is a varied 0-12v signal based on engine rpm, I would think that it would work. Use of one of these modules would also allow one to tune advance/retard throughout the rpm band to make best use of his/her specific cam. Next would be figuring out how to limit the factor phaser to keep things in check - seems like I have heard of companies selling kits that do this already.
Am I far-fetched to think that something as simple as this could solve the VVT with a carb dilemma? Granted nothing is ever as easy as it sounds, but the base logic seems to be there
04-20-2013, 05:32 PM
#6
Don't take my word for 12v being correct for the phaser solenoid, I don't know.
I'm sure any PWM control system could be programmed to control the vvt.
My personal choice was to eliminate it, as the gains do not outweigh the cost/ complexity to make it function.
You could leave the stock LY6 cam in it, and just replace the upper cam gear and retaining bolt, front cover and cam sensor extension harness and be good to go. My ly6 in this configuration moved my 67 camaro to 12.59 @109 in the quarter! Lots of power for a stone stock engine with a carb conversion and headers. and it reved nicely to 6500.
I'm sure any PWM control system could be programmed to control the vvt.
My personal choice was to eliminate it, as the gains do not outweigh the cost/ complexity to make it function.
You could leave the stock LY6 cam in it, and just replace the upper cam gear and retaining bolt, front cover and cam sensor extension harness and be good to go. My ly6 in this configuration moved my 67 camaro to 12.59 @109 in the quarter! Lots of power for a stone stock engine with a carb conversion and headers. and it reved nicely to 6500.
