EVOVII_SWE

So as the title says, will I have PtV issues on a stock LS7 engine? Anyone that knows for sure?

The 88958723 stage 3 cam together with titanium retainers and dual valve springs is supposed to go into an LS7 crate engine that I have in my AC Cobra replica. I’ve been running it stock for a few years now except for 2" headers, 4" sidepipes, 4" intake with K&N filter and I have the GMPP LS7 engine controller kit.

v8sten

HOLY Schnikes talk about a split duration!!!! and that LSA!!! hope you dont need vacuum or plan on any power adders. Those HP/TQ numbers have to be at the crank. I personally dont think you will have a ptv issue, but if you are unsure always measure

https://sdparts.com/details/gm-perfo...arts/k88958723

Specifically released as a cam upgrade for the LS7 engine, these cams will work with all LS style engines --- nasty sound and big torque. Also includes 12499225 LS7 lifters.

Advertised Duration (I/E) 294/335
Durartion @ 0.050 233/276
LSA 107
Lift (w/1.8) 0.630/0.630

LS7 engine-dyno results with "Stage 3" cam show;

600hp @ 6800rpm
526ft-lbs @ 4900rpm over 450ft-lbs from 3200 to 6800rpms

fueledpassion

Yeah and mine makes over 450ft/lbs from 3600-6600 rpms and it is a WAY smaller cam on the same stock exhaust, granted, I have a mild port done to my heads. Essentially a Stage II from WCCH, with small changes.

That cam will be a dog below 3K RPM's though. Headers or not.

RedZ4me

Sidepipes???

I would bet money you'll regret that cam unless you live in the high rpm's all the time

fueledpassion

Yeah, essentially, 335 out of 360 degrees, this cam has an exhaust valve off the seat, which means it will make GREAT power up top but it will not make any cylinder pressure until it reaches a very high engine speed.

The forever open valve will keep bleeding the pressure off!

Then there is the 40.5 degrees of overlap @ .050"

v8sten

EVOVII_SWE moral of the story is, that there are better choices out there than this cam. For example any of the Brian Tooley Racing N/A grinds. I personally have the BTR Stg 4 (the biggest & wildest one he offers) cam in mine and it drives great, with enough vacuum to operate everything that needs vacuum to operate.

C6 Curtis

Nothing wrong with that. My LG7XX cam has 40* of over lap and I'm turbo. Worked out fine for me 837whp@6psi

-Curtis

EVOVII_SWE

Thanks for the input

I bought this cam quite a few years ago when I bought the LS7 crate engine back in 2008. I didn’t really understand how extreme it was at that time and it has just been laying in its box since then.

As my car is rather light weight at around 2200lbs I would prefer a cam that does not make too much torque in the lower rpm range, more than a 427 will anyway from displacement alone, as I have traction issues as it is.

The car is far from a daily driver, and I have only done about 3000 miles in the 4 years it has been drivable. I have nothing that runs off of vacuum except for the brake assist. I already have the cam, TI retainers, dual high lift springs and HP tuners in a box in the garage so I was thinking that maybe I could always give it a try.

Any more suggestion to alternative cams otherwise?

Attached a couple of pics of the car btw.

double06

I think you want to stick with something with no more than 20-25 degrees of overlap. Tuning becomes a nightmare and you still have to drive car around. Furthermore is it really worth that much more hp for crappy drivability. I would get something in the 230/240 range and a 110-114 lobe separation. Even a Katech Torquer or their K501. Being your car is so light you really do not need much.

Michael_D

I love the Cobra Kit. My ultimate dream car is a 427 AC Cobra. A kit would be a good compromise, seeing how I'll never afford anything but a kit.

So anyway, the GM stage III cam is pretty dated. It does make good power, and 650 crank is and has been done many times. The advertisement just say's 600. The cam was designed for a direct slide in and be done it sorta install.... No port, induction or exhaust work. That's why the split is so great. I personally would not use it. I think there are many options available today that are better. But unless you work the exhaust ports, you should stick with about 20 deg more exh duration.

To answer the original question about PTVC, no - you should be fine. But you really ought to verify with modelling clay, jus to be sure.

EVOVII_SWE

Thanks, yea, the AC is a cool car, this one has a lot of GM stuff in it so not very accurate history wise C4 ZR1 front and rear with a Dana44, obviously an LS7 and a 5-speed manual TKO600RR gearbox, C6 Z06 front calippers and so on. I could also not afford a genuine one even if this didn't end upp the most inexpensive replica ever built.


Do you have any suggestion on specific alternatives to this cam?

Michael_D

What kind of power are you looking to get out of it? Is low rpm Drivability a priority? Are you going to have the heads worked?

v8sten

BTR Stg 3 or 4 both outstanding cams.

With the proper tuning the Stg 3 cam can drive like a stock cam and make great power, has more mid range power than the Stg 4
238/250 .652"/.630" 113+3
http://www.briantooleyracing.com/nat...-camshaft.html

The Stg 4 cam is a little more wild and makes awesome power above 3500 RPM, makes more power in the higher rpm range
246/254 .652"/.630" 111+2
http://www.briantooleyracing.com/nat...-camshaft.html

I personally have 1st hand experience with both, and I love them

EVOVII_SWE

Well, I really don't need any more power in that sense But I'm very fond of the rough idle and sound of a cammed V8, I'd like people to know that this car means business just from the sound of it But as I mentioned I would prefer a cam that doesn't make too much torque down low as I really have no use for it traction wise. I would however like to have an engine that pulls hard up to 7k and maybe a tad above that as well.

I wouldn't say that low rpm driveability is a top priority, I drive that car so little every year so I guess I could always go a gear lower than I do now. Also the gearing of the car is not that tall with a 3,45 rear and a 0,87 5'th, theoretically I have a top speed just shy of 300km/h or about 190mph, so far I have done 285km/h about 180mph GPS verified but it starts to loose power when I get to about 6,5k rpms.

I have no current plans for any other engine work at this moment no.

EVOVII_SWE

Thanks, I'll have a look at those, any videos around showing how they drive and sound?

fueledpassion

Does the car build the pressure fast? Or does it take 5K rpm's to get there? Just wondering.

I'd figure that much overlap would bleed out too much of the boost.

fueledpassion

And mine is:

236/244 112+3 .650/.639

Advertised durations are 288/298

With an aggressive open ramp rate and slightly softer closing rate 370 vs. 350

-------------------------------

This cam, with no other supporting mods but WCCH Stage II heads gave me roughly 60rwhp/40rwtq. It is an aggressive cam and I feel like I am on the bleeding edge of what a cross-country touring car should be able to do comfortably. I wouldn't go any bigger.

@ .050", the overlap was 16. I wouldn't go any higher for a streetable setup, but in your case, because your car is so light, I actually don't think you need to go even this high.

Usually, big overlap is because we try and work the LSA down to a better number for quick cylinder pressure build-up or because the duration is so large. Either way the power curve is usually too high and takes a while to generate the TQ needed to make power.

A smaller duration with a little higher LSA would make since in your case since the car is so light. A Katech Torquer 116 comes to mind or the BTR Stage II LS7 cam or even the LS3 Stage II cam on a 1.8 setup.

Michael_D

Firstly, you should have the heads disassembled and inspected. I can provide you info on that if needed.

Secondly, my idea of good street manors is on the conservative side. I would look to EPS and / or Cam Motion for your camshaft. I would look for a stick with int/exh duration at fifty of 225/245 +/- 3. Keep total valve lift under .630 on both sides with stock rockers. LSA between 114 and 117. It will sound lumpy, have good all around performance up to 7100. Mild surge under 2000 rpm.

Undy

This is what you really need in that Cobra.



482" of pure all aluminum 427 side-oiler.

v8sten

I agree with having the heads checked out, that is a very important aspect, not to overlook.

Based of what you are saying here, seriously look into the BTR Stg 4 cam. Here is my idle video of this cam. I also think it is important to note that a guy by the screen name of LS7BUD is running this cam and he is a top contender for the #1 spot in the, 6 speed, n/a position running a 9.84 @ >140 mph