VVT of aftermarket cam with Supercharged

[shinysun]

Hello,

I have Camaro 2017 SS with PD blower and it has a forged engine with TSP VVT-1 Cam. TSP gave me a sheet for cam retard, not much , but about 4* retard at high rev.

My question is that I better use the cam retard on supercharged engine? I assume it is workable for N/A engine, but not sure about S/C engine. I think Many guys just zero them out.


and secondly, about cam phase limiters or lock outs. Why do I need to limit or lock-out the phaser hardware-wise? Can I just remove VVT function on ECM, I mean on the software level.

Is it for just in case?

Thank you in advance.

[RySmDPT14]

I zerod my tables out when I did a turbo set up. I found that running the TSP tables caused a decrease in boost levels. At Wot I would only get 5-6lbs, when zeroed I was able to get full 16 psi. The limiter is there to prevent mechanical interference, yes they are non interference from factory but with increased lift from the cam you run risk of a valve clearance issue. What if the solenoid fails at high RPM (software)? You then have no mechanical stop therefore the valves and pistons clash.

[shinysun]

Thank you! Now, it is clear.

[NotSure]

OP is running a PD blower, which should have somewhat different valve event requirements than a turbo. From what little understanding I have, a PD blower engine likes early EVO events to let the exhaust out, so retarding the cam will make that worse. I am running a stock VVT Gen4 with a PD blower and it seems to have improved since I zero'd out the cam retard and "parked" it. No empirical data though, just what I see in MAF g/s changes, in a very non-controlled environment, lol. It seems directionally correct to retard the cam as rpm goes up, but I think if you have a N/A cam to begin with, retarding the EVO ends up hurting you overall with a blower. An off the shelf PD blower cam usually has EVO much earlier than a N/A cam. With turbos you have a spool factor and some other science stuff to consider which I know even less about.

shinysun, you could try, preferably back to back on the same day, running the cam as they say then zero out the cam retard and run it again, monitor away and see if there is a change in MAF readings. You might ask TSP as well, as it sounds like it was not a blower-specific cam?

[shinysun]

OP is running a PD blower, which should have somewhat different valve event requirements than a turbo. From what little understanding I have, a PD blower engine likes early EVO events to let the exhaust out, so retarding the cam will make that worse. I am running a stock VVT Gen4 with a PD blower and it seems to have improved since I zero'd out the cam retard and "parked" it. No empirical data though, just what I see in MAF g/s changes, in a very non-controlled environment, lol. It seems directionally correct to retard the cam as rpm goes up, but I think if you have a N/A cam to begin with, retarding the EVO ends up hurting you overall with a blower. An off the shelf PD blower cam usually has EVO much earlier than a N/A cam. With turbos you have a spool factor and some other science stuff to consider which I know even less about.

shinysun, you could try, preferably back to back on the same day, running the cam as they say then zero out the cam retard and run it again, monitor away and see if there is a change in MAF readings. You might ask TSP as well, as it sounds like it was not a blower-specific cam?

I tested it on dyno yesterday with gen5 lt1 stock cam on/off, but the result was...

1. stock retard. (10* retard at 6500 rpm)

Boost level : 0.91 bar (about 13 psi)
Cylinder air mess at 6500rpm : 1.58 g/s
Rwhp : 636 hp

2. Cam retard zeroed out

Boost level : 1.15 bar (about 16.5 psi)
Cylinder air mess at 6500rpm : 1.53 g/s
Rwhp : 615 hp


3. 4* Cam retard at 6500 rpm (Gradually increased from the 4000 rpm)
Boost level : 0.95 bar
Rwhp : 626? hp

[NotSure]

Interesting results. Did you put a phaser limiter on it? If not I would be concerned of valve interference if the phaser ever loses control for whatever reason, given the higher lift and duration. You could always zero out the cam retard so it stays parked, and sacrifice a little power for safety.

[shinysun]

Interesting results. Did you put a phaser limiter on it? If not I would be concerned of valve interference if the phaser ever loses control for whatever reason, given the higher lift and duration. You could always zero out the cam retard so it stays parked, and sacrifice a little power for safety.

I just played with stock cam which has quite low profile at this time. So no limiter or lockouts for it.

[IARLLC]

Yeah, with a stock LT1/L86 cam you can retard at least 28 as evidenced by the factory tables.

Shinysun, thanks a lot for the info. Looks like retarding the cam 10 (stock) let more air in the cylinder (lower pressure/boost stuck in the intake,more HP). I wonder what 8 and/or 12 would have produced. Thanks again.

[NotSure]

I am confused, were the tests done with the stock motor, and the TSP cam is not installed yet?

[shinysun]

I am confused, were the tests done with the stock motor, and the TSP cam is not installed yet?

Ah, the motor tested was not mine. One of my friends got his forged engine with stock cam tuned, at that time , I ran a little variation of cam retard.

The next time , will be tested with mine with aftermarket cam. Probably 0 retard vs 4* retard.

[RySmDPT14]

I tested it on dyno yesterday with gen5 lt1 stock cam on/off, but the result was...

1. stock retard. (10* retard at 6500 rpm)

Boost level : 0.91 bar (about 13 psi)
Cylinder air mess at 6500rpm : 1.58 g/s
Rwhp : 636 hp

2. Cam retard zeroed out

Boost level : 1.15 bar (about 16.5 psi)
Cylinder air mess at 6500rpm : 1.53 g/s
Rwhp : 615 hp


3. 4* Cam retard at 6500 rpm (Gradually increased from the 4000 rpm)
Boost level : 0.95 bar
Rwhp : 626? hp

Stock cam isn’t the best for boost applications. The VVT-1 is’nt too bad for turbo boost. Gary at Texas speed suggested keeping it after I asked about a different cam.... I’ve tried the whole advance/retard the cam to gain higher rpm boost etc.... best results 0’d cam timing. With a blower, you will want different cam lobe profiles to take advantage of the instant boost at low RPM . Call TSP.

[Jonblarc7]

So what boost would be best for my TSP VVT-2 in my L86. It's a 218/226 .635.635 I think it was a 113 LSA and 32% over fuel lobe. At this point with my small lift and mud tires it's not ever going to be an all out performance truck. But I would like to pick a type of boost that works the best with what I already have.

[IARLLC]

RySmDPT14,
The TSP tables probably created more power. With a supercharger, more boost (pressure stuck in the intake manifold) at the same rpm, just means that something is restricting it...worse valve timing. This situation raises intake air temps as the power adder fights the restriction (more detonation). With your turbo, there is a chance that you'd see marginally increased boost from increased exhaust flow because of changed valve events...but the kind of major change you mention, (16 compared to 5-6) looks to me like you are closing the intake valve too soon (parked at 0). Shinysun's numbers point this direction.

If there is no dyno, I would run your tests again comparing MAF and IAT numbers between TSP tables and yours. My bet is that parking the cam is reducing MAF and increasing IAT, less power.

I don't mean any offense at all, just an observation that I hope helps.

Merry Christmas to all!