langsbr

For a bit of history - car is a 2001 Coupe I purchased off the forum here back in April. It dynoed 360 RWHP /335 RWTQ with the following mods:

LS6 longblock
LT headers, Corsa catback
Vararam


I installed an England Green Whiplash II cam recently, and I'm very pleased with the results. I will say I have questions, as I'm curious to say the least.

Car made 420 RWHP / 350 RWTQ with the cam.



I was pleased that there was no loss of power even down to 3000 RPMs. Perhaps even more surprising to those that say you give up a lot on the low end for more at the top, I didn't lose anything all the way down to 2500 rpms:



Note that this was an unfinished tune run, but I asked the dyno operator to start it at 2K, and he did it at 2500...


On to my questions.

First - why does it peak SO high? I know it's a big cam, but most of the other dynos I've seen of this peak around 6200 - mine is peaking at 6600, and the torque is only just starting to taper. I'd think it would be good to shift at 7K+ for best E.Ts, no?

Second - Why is torque so low? It's not terrible, but I feel that it's about 30 - 40 RWTQ down from most other combos, across the board. Even stock, it seemed that it made less torque than most combos. I'm at a loss - any thoughts?

My thoughts were possibly the bottom end was a 5.3 and not a 5.7. The heads are indeed 243s, and had yellow springs. I checked the casting number on the back of the block and it's indeed an LS6. That throws out my idea that it coudl have been an L33 block.

My only regret was that I didn't degree the cam (though it would have been with nothing to compare to, as EG wouldn't even give me the valve events). Also, with a cam this big, if the cam or timing set were off a few degrees and it was too far retarded, I'd think I'd have valve clearance issues, no?

My tuner (Mike Bruce with B&B Corvette in Columbia, SC) said it took more timing than he normally sees. That also led me to thinking it might have been a smaller displacement motor.

I'm going to put a bore scope on a cylinder this weekend to see if the pistons are indeed the flat top LS1s. Since the block number is right, I don't see what else it could be.

I'm open to suggestions and criticism.

I will say - this cam drives great for something this big. I used to have a GM847 cam in an LT1 and never had an issue with it. Big cams are the way to go I think...

RonSSNova

Do you know the approximate specs on the cam?
I wouldn't think it's a 5.3 given the HP. but it would be nice to know what pistons are in it. Compression really helps with the torque.
Agree on the cam timing, but your hands were tied there.
Going to be interesting to investigate.

Ron

langsbr

England Green says the Whiplash II is 24x/25x with .630 lift.

I keep thinking if it were a 5.3, there's no way I wouldn't have valve clearance issues, but the LM7 iron block has 9.5:1 compression and valve reliefs, but the L33 has flat top pistons with 9.9:1 compression.

Anyone have any other ideas where the missing torque could be?

I do have an M12 trans and 3.90 gears, so that will take a tiny amount compared to 3.42s, but not 30+.

Full combo now is:

LS6 engine?? - 243 heads
Manley dual valvesprings
Whiplash II cam
LS6 intake
LG LT headers w/ OR X pipe and Corsa exhaust
Vararam intake

Rob Petyo

Ls-6 throttle body?

what injectors?

what MAF?

langsbr

I thought the LS1 and LS6 TB were the same size at 78mm? Is that not the case?

I'm running stock injectors - not having any fueling issues, so I didn't think that would be a source of the problem, especially since I would think that would present itself only at the higher RPMS, and torque is low across the board.

MAF is an 01+ 85MM.

langsbr

Ron, curious, why would you think the HP would lend it to not being a 5.3?

I've always understood cubic inches to be indicative of torque, not HP. Hence, a 5.3 and 5.7 with all other items being equal would make the same HP, but at different RPMs, with the 5.3 peaking later, and having less overall torque.

I know guys that used to build 383 SBCs but used their stock heads and cam, and then were surprised when it makes the same HP at a lower RPM, but gobs of midrange torque.

Water_Walker

I have talked to Stephen, who is very helpful. I have the same cam, yet it is not in the car yet (02z). 420-440HP is the expected HP with this cam on 243 heads. I completely agree that the torque is way off. Unsure why, which I know is your original question.

langsbr

Don't get me wrong - I'm very pleased with the overall results. I am too much a creature of logic and like to know the underlying why behind things, instead of just saying "that's what it is."

Similar combos should create roughly similar results - there has to be a 'reason' mine is so different, be it the cam is retarded, lower compression pistons, lower displacement, etc.

Does anyone know if simply having lower compression pistons would do that? Also, what about thicker head gaskets? I was wondering if that would lower compression enough to reduce torque that much. Since torque is pretty flat across the board, I'm leaning towards displacement or compression and not cam timing, but I'm really just speculating.

0EG@EnglandGreen

Horsepower is right where it should be, but torque is definitely low - should be in the 375-385rwtq range. However, the torque curve is completely flat, which is better than we normally see from a LS6.

"Similar combos should create roughly similar results" - only if the car is 100% bone stock in excellent mechanical and electrical condition as your starting point.

Also remember, a 1997 C5 (for example) is now a 15 year old car. Even a 2004 is 8 years old. These are mechanical objects and they do wear, sometimes unevenly.

Stephen

langsbr

What could wear that would cause torque to be low? I can do a compression test and leakdown test to see what might be the issue, but wouldn't horespower be affected as well if it's a ring sealing issue?

Again, I'm not disappointed since I did gain 15ft. lbs of torque from my baseline, and didn't lose any hp or torque anywhere, just interested to find out what would be the root cause.

Stephen, would you have any insight as to what leads it to taking more timing than normal? I can email you the timing map if you'd give it a glance and let me know if it's above what you normally run on this cam.

Also, interestingly, you guys did all of the original work on the car before I purchased it (install of the LS6 engine, clutch, master cylinder, trans, etc.) My friend that owns an auto shop here in SC said he was impressed with whoever worked on it before -typically you see harness holders cut or broken, perhaps a missing bolt - everything was in place and proper when we did the cam swap.

RonSSNova

Can you put the timing map in a .jpg file and post it?
What I've found with mine is that it likes less timing (22) at peak torque and more timing (27) at peak HP.
Maybe some of the more savy tuners will chime in, mine is tuned at the track, hasn't been on a dyno.
My cam however is much smaller.........226/230

0EG@EnglandGreen

Thanks! We try our best to do a good job!

I'll post up some Whiplash II timing maps on Monday; we're closed today for Thanksgiving.

0EG@EnglandGreen

Whiplash II spark map, as promised. I normally run 27-29 degrees with this cam, depending on other mods and how the car is responding.

2001 LS1 Coupe, 131,000 miles, LS6 heads, LS2 intake, 90mm TB, 100mm MAF, Vararam, Kooks headers, cats, Bullets.

Water_Walker

Stephen...a man of his word. Great business here folks!

RonSSNova

My timing table is quite a lot different. although I am sure no 2 are ever the same, except stock ones.
Thanks for posting.

Ron

mchicia1

You have ported 243s, no?

The table posted looks like timing for a stock 241 headed car.

langsbr

The descirption of mods says it has LS6 heads, fwiw.

Thanks for the info Stephen - I'm still trying to get the file from my tuner so I can compare. I'll post what mine is at as soon as I get it.


Thanks

Brian

mchicia1

Oh ok, but Ron's heads are probably milled too which raises comp and won't allow much more timing than what he has.

RonSSNova

Correct, plus they are AFR. So my timing results will be different. Also on 92 octane E10......pretty poor fuel actually.

Ron

fotoboy

I'd try a different dyno just to compare.