Running on the Dyno with my LS6 on Friday

[k92]

I found the article that I was refering to.... It's from Super Street Cars Feb '71. At 1st the bone stock LS-6 owned then by Eddie Fitzpatrick, showed 220 hp at 4800 rpm at the rear wheels and 460 lbs of tq. After removing the smog equipment,installing headers, aftermarket intake, 850 dbl pumper with carb spacer, .080 jets all of the way around,ACR43T plugs gapped at .035 and a distributor curve the engine showed 310 rear wheel power and 700 ft lbs of tq at an engine speed of 6000 rpm.They then put in .082 jets all of the way around and got 350 hp and 720 ft lbs of tq.Lastly they closed the headers and put on the air cleaner and got 290 hp and 670 ft lbs of tq!!! With 7" slicks and open headers it ran a 12.51 at 111 mph. ALSO, concerning the dyno test in muscle car review,they had headers on that mill and had to play with the timing a lot and it had an after market cam to get the numbers that they got.Expecting 450 plus hp out of a STOCK ls-6 is wishful thinking.Dont get me wrong, I'm not knocking the ls6, I have 1, but the hype about their power, amongst other things, has caused part prices to balloon out of this world!!!

[Mr70]

I picked up a 1970 Chevrolet engine Dyno test booklet.
It shows the ACTUAL RPM/Horse Power ratings for all the 1970 Engines.Graphic charts and tech. notes,etc.
The LS6 engine shows it making a Max. of 446HP.
I don't remember the RPM range at that percise moment,but I can look it up if anyone is interested.
Good book,I just had to have.

[Chevy454]

4800? That's seems awfully low to me. I'm thinking my LS-6 peaked around 5300-5500, while my L-72 peaked at 5800...both of these numbers are through exhaust manifolds. (Edit: I found my dyno sheet and the LS-6 peaked at 5400.)

That dyno test in MCR has always bothered me, because a the square port BBCs should ALWAYS be able to equal their displacement in horsepower, even through manifolds. My LS-6 and L-72 did, as have Pete and JJ's engines. And Moparts can vouch for my L-72, as he walked me through building it...there's nothing trick about that thing! Not that we couldn't, but we didn't. I see no reason an LS-6 shouldn't be over the 450hp mark through manifolds (on an engine dyno of course). That would be 1hp per cube, which is pretty conservative. An interesting side note is that Jensen is running his full smog setup and dated wires on his LS-6.

Rick: I've heard you speak of this book before, but have NEVER seen one! I'd love any info you'd care to share.

[JLerum]

I can honestly say that I've seen Dan's cylinder heads before they were put on the motor. Nothing but a very good valve job. Dans car is like alot of the cars that go really quick at the Pure Stock Drags........attention to details. I asked Dan what his leak down was on his car and he gets 1 to 2% on all 8 cylinders. The cam is stock from GM. He retarded it 5 degrees because that is all the timing chain would allow. He wanted 1 more degree out of it but couldn't. The motor is 12:1 compression and idles like a pussy cat!

JIM [img]/ubbthreads/images/graemlins/flag.gif[/img]

[Chevy454]

I was hoping you'd stop by! I tried to get my heads done at the same place, but never could get it set up...plus, getting them to Michigan and back would have been a chore.

I know it's hard for people to understand, especially when you see all these magazine articles hyping this and that. Unfortunately I think a lot of the articles are just "info-mercials". It doesn't take voo-doo to get a BBC running through stock (read: unported) manifolds to get 1hp per cube. Heck, if I can do it, I know it can't be THAT hard!

So, Jim, got that LS-6 squared away? Find out what wiped out the cam?

[JLerum]

Their are so many lessons to be learned from my motor build up and it makes me cry. lesson number...............


1. Don't take your motor to someone that doesn't believe what you do even if they are a well known machine shop.

2. Don't take their word it is done the way you want when they have a different falocify.

3. Make sure you go to someone that understands the events you run. Because as stated the shop doesn't beleive for a second that you can run low 12's with a blue printed motor on Wide Ovals at 3800lbs.

I waited 9 months to have someone set me up with 148lbs of seat pressure on a cam that requires 120 and refussed to setup a cam retarded unbenounced to me. The list goes on. After over pressuring these people to get the job done and $1500.00 later I'm the looser. FASTIMES MOTOR works did me s**t work.

The motor on a dyno(not FASTIMES) pulled 420hp@4900RPM and 518 ft/lbs@3600RPM. After some pulls it was obvious the moter was loosing power and high oil temps made us stop. The leak down was 15-20% and the exhaust lobs on #7 and #8 were going down.

After disassemly the cam was 6 degrees advanced 148lbs on the vavle springs. (max spring pressure for non single spring breakin is 130lbs). Their is more but I'm not going to go there. I can not stress lesson #3 enough. The motor should make 470 to 480 HP and around 535lbs of torque to my best estimations. Yes compression is important. It makes big ports work and give strong signals to the induction system.

JIM

[Chevy454]

Boy, Jim, reading you post made me even more nervous about putting the finishing touches on the L-72! I'm *suppsoed* to pick it up Tuesday...

[Mr70]

Is Dan Jensens LS6 the Fathom Blue one that Gilbert Probst restored for Floyd Garret?
I have a Videotape of an Old "My Classic car" segment with Dennis Gage and Dan at the dragstrip running this Chevelle 3X with a Camerman in the backseat to boot!
Pretty impresive times..

[SS4Real]

I had my LS5 on the Dyno at Superior Engineering in Anaheim, Ca last year. The numbers showed 287.6 peak HP at the rear wheels with 415.7 max torque. The engine is stock (balanced and blueprinted) running stock exhaust manifolds. The only upgrade from stock is 2 1/2 exhaust with Dynomax mufflers. Your LS6 should be better than that in proper tune and condition.

[Chevy454]

Those numbers are right on where an LS-5 should be, SS4! [img]/ubbthreads/images/graemlins/biggthumpup.gif[/img] That puts it in the 320 NET hp range, or 360 GROSS hp range...right on!