Yeah, I'm running the VHP 047. If you read any of my posts, you'll see how nutty I am over this thing.

I finally got to the track - my times are below. Stock, I think these trucks run between 15.0 and like, 15.4.

My only major mods are the cam, amatuer tuning, cat-back, and e-fans. I'm running the mildy cheap Comp 918 springs and TR 7.4" pushrods. Other mods are plug wires, plugs, drop in filter, and very mildy ported TB. I was shifting at a meak 5,800rpm.

Power below 1,500 is softer than stock. Betwen 1,600 and like, 1,800 or so, the cam wakes up. By 1,900-2,000 it's making a healthy amount of power (more power than stock). It's VERY torquey when it 'wakes up'. It's a lot of fun to drift between like, 1,700 and 2,200 rpm on a nice twisty road. Makes good smooth strong power to 6K - but I haven't been much over that. (just a personal preference of mine)

A question for everyone: A lot of people mention "area under the curve". What do they mean by that? I always though it was the power curve BELOW the "meat" of the powerband that you look at on a dyno run. Low end and midrange power, basically.

With the VHP 047, I found that the cam requires MUCH less throttle to do the same amount of work during daily driving as a 220/220 cam needed in my motor. That made me rethink the term.

If -that- is 'area under the curve', then the cam is EXCELLENT for that.

 

I've posted this before but I ran the Comp 206/212 in my Camaro SS for a while before I got ported heads and went a little bigger. That cam makes monster, rat-block style off idle torque. You'll definitely have traction issues. I don't think there is a better low-end cam on the market, and with my stock heads it pulled pretty well to 6000 RPM.

I even used my stock springs and pushrods for 10K miles with no issues. For a little insurance, though, you should upgrade your springs to Comp 918's or the like.

 

Traction issues are my kind of thing

As for the 112 lsa not being supercharger friendly, i did hear that sc's have more trouble building up boost on low lsa cams, should this be a deterrant from this cam? should i opt for the vinci 043 instead, specs below:

DUR @ .004" 272*/280*
DUR @ .050" 210*/218*
LIFT .531/.531
OVERLAP 48*
LSA 114*

Thanks again, im almost done and getting closer to making a decision

 

Not to confuse matters but on my current project, a Radix-boosted Silverado SS, I am going with the LPE GT2-3 cam. Specs are, I believe 207/220-.573/.580-118.5CL. This cam was designed by Lingenfelter to be a sleeper street cam on its own, and to work well with a Magnuson supercharger. There is no overlap to bleed boost and the long exhaust duration helps scavenging when the engine is being forced-fed on the intake side. The wide LSA also keeps the idle silky smooth. I just bought the cam+springs on sale at LPE for $399.

The Comp 212/218-.558/.563-115LSA might be another option. With low duration cams you can get away with a wider lobe separation angle and little or no advance and still have good off-idle torque, while extending the powerband a bit further into the upper RPM's. I don't think I would go below 114-115 LSA on a boosted application depending on duration. Overlap results from a combination of duration and LSA. Generally speaking higher duration = more overlap, and lower LSA = more overlap, all other things being equal. Big duration + tight LSA = lotsa overlap. Good for peak torque N/A but bad for idle quality and bleeding boost. Hope some of this helps.

 

How much boost would i be loosing realistically by going with a 112 lsa as opposed to 114? say i was putting down 6#, how much of that would get blown through??

Thanks again!

 

SSLink summed it up pretty good.

Overlap is the main thing to pay attention to with F/I cams.

I find this one thing intersteting though. Comparing two VHP cams.

My cam: 210/218 on a 112LSA. It's listed as having 52* of overlap.

On the SUV cam page: 216/224 on a 115LSA. 53* of overlap.

The 216/224 is quoted as being great for a blower application... but with my 1* less overlap, I can't help but wonder how well my 112LSA cam will work.

It's definitely not a F/I designed cam, no doubt about that...

I've been toying with the idea of running a Radix - but I really don't feel like swapping cams *again*.

--

One more thing sort of on topic - I was reading a magazine article recently, I think actually this months Hot-Rod. They said something to the effect that boost is effectively a measurement of restriction in the manifold... and that they've seen motors make more power running a cam that showed less boost vs another cam that showed more.

 

This is only a guess because it depends on the rest of your setup. On stock heads with stock exhaust you might lose 1 PSI or so. Then again, with average duration at 209 or so at .050" lift you're still not going to have a lot of overlap and the impact may not be great.

Keep in mind that anything you do to increase airflow in your engine under the blower is going to lower boost somewhat, all other things being equal. For example, ported heads, a cam with higher lift, or headers will all have impact. But as Marc indicated, losing boost doesn't necessarily mean losing power. You can have lower boost but higher cylinder pressure and good exhaust scavenging and make more power.

The thing about valve overlap is that it's kinda like compression. In a tradeoff with boost, boost generally makes more power overall. Any of this make sense? FI experts please chime in...

And Marc, come on! We know how much you love swapping bumpsticks. I am counting on you finding the perfect cam for the LQ9!

All the best - Jeff L.

 

Great discussion! I don't want to steer it away from the blower topic, but I just had a little bit more to say on the 206/212. With an M6, it seems like you'll "clutch" past some of the meaty part of torque and waste it. The 212/218 or Vinci grinds might match an M6 better.

Also, I agree with Tranzor when he says with 4.10s you'll row through the low end power pretty quickly. What you should be camming for is a strong midrange with an improvement in the lowend. The 206/212 is a strong lowend cam with an improved midrange.

 

Maybe just one more...

 

nuzee: clutching through some of the strong low-end is one thing that i've been a bit concerned about....

Back in the FI world, does overlap affect compression? if so, how? if not, does any aspect of a cam increase or decrease the compression ratio in an engine?

The smaller overlap is what caught my attention on the vinci 043 since it has only 48 overlap, not too bad, and with duration of 210/218 and 114 lsa maybe this is the cam i should aim for instead.... It should still give me nice low-end tq and good mid range and preserve my boost levels. Has anyone tried this grind?

 

ASA cam Pulls hard low end and has power throughout rpm range.. bad blower cam IMO though.

 

That Vinci 043 looks like it could make a decent blower cam. A little overlap but not too bad.

And yes, big cams with big overlap do lower effective compression, even in the N/A world, just as they bleed boost and effective compression in the FI world.

 

Comp has a high lift version of the 212/218 on a 115lsa. Not only does it make alot of low end it also has a broad powerband. The standard 212/218 is very torquey as well and it only has .522/.529 lift so Comp 915's or even ZO6 springs are plenty.

 

Ok, let me thrown in one more cam into the equation...

The lpe gt2, with 205/212 .540/.540 and 116.5, how would this cam play into my needs?

Also, if say i was going to go for the cc 206/212 112 and noticed 1 psi loss on the supercharger, can i just run a smaller pulley to make up the boost or would that be a bad idea??

Thanks again everyone! this thread has been extremely enlightening for me

 

Yes, you could run a smaller pulley as long as you're not getting to the point where you are overspinning a small blower, like the Magnuson Radix, or getting to risky levels of heat or cylinder pressure.

On any stock bottom end I would keep boost below 10 PSI, at 10:1 compression or lower. At higher CR's be careful with your boost and tuning as KR, or worse, detonation could occur.

I think if you shoot to keep boost in the 8-9 PSI area with your choice of cam you could have an ideal and reliable setup for the street.

The LPE GT2-3 I mentioned is an improvement on the GT2, but either would work fine on your application.

 

Hm sounds good.... correct me if im wrong on this ->

with the CC 206/212 112 i will lower the boost by having some leak out, and at the same time lower my cylinder pressures, which in turn i am bringing back up by running slightly higher boost via a smaller pulley. Does that sound about right? lower lsa = lower boost and lower cylinder pressures?

If this is the case then i am going to lean towards doing that and just stand in one place as my wheels rip up the grond because of all the tq off line

 

Sounds like the right idea to me. Very similar to my goals on the SIlverado SS.
With AWD I know I can make use of the torque off the line. Only difference is that the intercooled Radix really comes close to maxing out at 8-9 PSI on the 6.0 Liter Lq9. I am attempting to compensate with a bit higher compression, a cam that won't bleed much boost, and of course, the right tuning.

The only thing I have against the 206/212 is that I think a tad more exhaust duration as on the GT2-3 and CC 212/218 cams is useful on SC setups. However, if longtube headers are in your future you won't need to worry because your exhaust will flow just fine.