EVOVII_SWE

Just had my car tuned and dynode after installing a GMPP stage 3 cam, 233/276 @ .050, .630/.630 lift, 107 LSA. I have had the cam in its box for many years and I know that many suggest newer designs today, but since I already had it I thought I’d give it a try knowing that it would be a handful to drive and that it wouldn’t like to be below 2000 rpms. On the other hand I thought that the general opinion was that it produced decent power if you could live with the drivability issues.

The conditions:

Stock LS7 crate engine (small clean up head mill when changing valve guides)
GMPP LS7 ECU kit tuned with HP tuners
Custom 2” headers into 4” side pipes, no cats
4” open intake with K&N filter

Last summer I dynode the car before installing the cam and got 499hp @ 6000 and 486 ft lb (659Nm) @ 4900 on a Dynopack 4000 hub dyno. Now I got 550hp @ 6500 and 478 ft lbs (649Nm) @ 5300 on the same dyno, so I actually lost a small amount of torque, the car pulls much longer in the revs now though and even at 7000 it still feels pretty strong.

This was the first car my tuner had done with this cam, and he said it was a handful to get it running decently, they normally use Brian Tooley Racing cams when they do LS7/Z06 projects themselves and he said they got upwards of 600hp with that setup with a lot better drivability than this. Not sure which BTR cam that was but I guess stg. 3 or 4.

Sorry about the orientation of the graph, got it as a pdf from the tuner. Thick lines are obviously with the new cam.

So, any comments on the graphs? I was under the impression that you could expect about +100hp with this cam but maybe that is not the case or you need other supporting mods like throttle, intake manifold, porting etc. to reach that?

Thanks,
Thomas

encasedmetal

there's not a cam available that will give you 100rwhp cam only.

Michael_D

You are at 550 wheel HP. Figure ~600 at the crank - which is about a 100 HP gain over stock.

Those side mount headers look cool, sound cool, and demanded to be installed on a Cobra. Unfortunately - they suck from a performance perspective. I built a 410 small block for a buddy a few years ago. It was going into his 74' vette, and he was going to use Hooker side mount headers. The engine made 640 crank hp on my dyno with some 1 3/4" headers I had laying about. I then put the side mounts on and it lost close to 25 hp, no other changes whatsoever.

I hate that GM camshaft too, but I already told you that last time you were asking for input.

EVOVII_SWE

Thanks Michael, I know you said you didn't like that cam I was comparing with my base line and figured that @ 499hp I should have about 540hp at the crank and then the cam gave me about 60 crank hp. Maybe that is as good as one could expect given the circumstances?

But what about the torque, I lost about 8 ft lbs while moving the peak up about 500rpms, is this also normal and to be expected?

Yeah, those custom headers is a compromise since it’s more or less impossible to fit equal length runners, and on the driver’s side the steering rod actually goes through the header. And the way the frame of this kit is made there is no way to have the exhaust running underneath the car to be able to use an X-pipe for a better exhaust design.

It might be that this is just as good as it gets with my current setup. I’ll just live with this cam for this season and we’ll see if something else goes in next winter How would a BTR stg. 3 and 4 compare to this cam when it comes to drivability? I’d still like a pretty big cam but obviously there are better design out there now.

Michael_D

I didn't even bother to look at the dyno sheet....

A loss in lower rpm torque is to be expected whenever you increase valve overlap. It's just the nature of the beast..... Give up low rpm torque for increased power at the top end. Do you prefer foreplay, or a happy ending?

If you go through this again, you really need to have someone who's damn good at selecting valve events specify you a custom camshaft. Because your car is so light, you can't just drop in any old camshaft that works for the Z06 and expect it to behave the same with your car. Not gunna happen.

EVOVII_SWE

A loss in lower rpm torque I understand but I was kind of expecting a higher number some where up the rev range. But that didn't happen, insted a got 8 ft lbs lower reading in total.

Specifying a custom cam, is that something that could be done theoretically or would that implicate access to the car physically? Reson for asking is that I would probably have a slim to no chance finding somebody locally here that could help me with that.

I converted the pdf-file to a jpg pic instead so it's easier to see.

double06

That cam has so much overlap I think it really needs much more compression and motor. Go buy the BTR stage 3 kit and have sent to you over there and have someone install it. It has like 20 degrees of overlap not 40+ you have now and you will pick up some torque. With the overlap you have now you are just blowing air out the valves so until you get it to like 5000+ rpm you will loose power. Maybe buy a Mamo MSD intake while you are at it.

Michael_D

Nothing out of the ordinary with those curves. The loss of Trq you are concerned about, really isn't much. That could be something as simple as the tires slipping on the dyno. There is also a difference where the runs started. It does take a moment for the engine to "catch up" with fueling to settling at the target AFR, when you initially go WOT.

Nobody needs to see the car first hand to spec you a camshaft. The cam guru will ask you a bunch of questions (and if he doesn't, he's no guru and hang up the phone). He will want to know all about the car; weight, drive train, gear ratio, tire size; ect. He'll also need to know the engine particulars, like your exhaust set up, intake manifold, air intake.....

Most of the real cam guru's will have a form with all these questions for you to answer. Many use software to help them find the optimal valve events. With their own personal experience, and considering the software results and the client's goals/needs, they get the cam profile on paper. Then it's a matter of lobe profile and just how aggressive (or not) the lobes needs to be.

You ought to just drive the car for a while. See if you learn to love it, or hate it.

hungryhippo

That cam looks like it was made for a carbed drag car. I wouldn't be surprised if your car was actually slower now.

EVOVII_SWE

Thanks, I'm definitely going to drive the car now and see, if I'm unhappy with it by the end of the summer I'm probably going to ask you which cam guru to consult

Btw, I have noticed that I have a lot more traction problems now even with my M/T ET streets so I guess that at least says something

MTPZ06

Cam Motion or EPS get my vote for a custom grind. If not custom, a BTR 3 would be a solid contender...but I feel your car deserves a custom touch.

EVOVII_SWE

Thanks, I'm going to drive the car now for this summer and then I'll know if I can live with it or not. If I'll be changing the cam again it will be done during next winter and in that case I'm going to have some time to look into what to get

EVOVII_SWE

I have now driven the car for a while and this cam is really a handful to live with. As expected it does not like to be below 2k much and I normally have to select a one-step lower gear than before. It sounds really wicked though, people turn and watch all the time thinking that it’s some kind of race car approaching

Even though it does not really show in the graphs the power delivery is rather different, it’s a lot “harder” even in lower rpms. I’m running 305/35-18 MT ET Streets and before the cam swap I could more or less floor it from a slow roll in 1’st all the way up without breaking loose the tires. Now that is impossible unless they are really warm, I have to let go of the accelerator to keep traction.

All in all it’s not the worst thing to drive the car this way but I do feel that the gain is not sufficient to justify the sacrifice in drivability, even though the car is far from a daily driver. So, the plan is to source a milder cam, I still would like something rather big but there should be alternatives out there that is easier to live with while still sounding awesome and producing good power.

Just for comparison, how would the BTR stg. 3 and 4 compare to the GMPP stg.3 all in all? And would the increased lift (.630/.630 GMPP vs. .652/.630 BTR 3/4) be an issue for the valve train having changed springs to PRC’s dual gold and ti-retainers?

If I go for a custom grind, what kind of money are we talking about then?

nuke61

Your result it right in line with what this guy got:

http://www.smokinvette.com/corvettef...250-post3.html

cv67

bigcam-itus bites another victim
you dont need a custom cam, enough have been made for the lsx just talk to someone that really knows their stuff.
That cam as said would probably be awesome in a carb'd lsx setup

As you found to live with fair sized cams (230ish@050 is mild) driving style has to change, can no longer lug it around like a stocker. Some have tolerance, others dont.;many guys get disappointed but refuse to regear or add complimenting mods to make it all work properly.

A good cam grinder can make a smaller cam still act like its bigger brother but going into the science of it can be confusing.
I recommend Mamo a lot as I dont have personal experience with the others out there but he will get it right the first time.
Good luck.