Running on the Dyno with my LS6 on Friday

[Chevy454]

The LS-6 for my Chevelle bettered the factory 450hp mark through the manifolds (an engine dyno), and I believe Muscle Car Review dynoed one and it did the same. And, you wouldn't believe what Dan Jensen's Pure Stock LS-6 is doing...

[ORIGLS6]

Rob,

I've seen Dan's car and read the numbers but just how close is he to "Pure Stock"? I've always suspected he rides the fence between "Pure Stock" and "Stock Appearing". I know he plays with Dist. curves, etc. and carb tuning, and that's acceptable. Just wondered what else goes on under that hood. Still.........pretty impressive! And much better than what I could do.

Dennis

[mmcporter]

[ QUOTE ]
Rob,

I've seen Dan's car and read the numbers but just how close is he to "Pure Stock"? I've always suspected he rides the fence between "Pure Stock" and "Stock Appearing". I know he plays with Dist. curves, etc. and carb tuning, and that's acceptable. Just wondered what else goes on under that hood. Still.........pretty impressive! And much better than what I could do.

Dennis

[/ QUOTE ]

It would be interesting to know what he has for valves, valve springs, cam, lifters, etc. They are all little things but they do add up to a radically different picture. Just look at the killer "L89" Nova run by the Brewers from Georgia. 12's on polyglass with a Turbo 400 tranny. Stock? Ummm errrr....not really...stock appearing? Yes.

[Chevy454]

I tell ya, there's a lot to be said for sweating the little stuff, but Dan's stuff is for sure "Pure Stock". His LS-6 is nothing trick by normal racing standards, just a "blue printed" LS-6...much like the L-72 we're putting together. When you blue print these big blocks to factory specs, you put 'em up in the 12:1 neighborhood compression-wise, which really seems to wake them up. But the key to the whole deal is the cam...and I don't mean a trick grind. Just the stock GM cam, but retarded. What people don't relize is the stock cams are ground 6 degrees advances...good for bottom end power, but makes it a booger to launch on skinny tires. Also, in a "from the factory" engine there isn't enough compression to work "well" with the cam. I've seen 9.8-10.2 compression ratios on stock L-72s! That was the norm, not the "11:1" advertised ratio we'd all like to believe we have. So, when you retard the cam, you basically put it back to "straight up", which kills a little bit of the bottom end (better for launches), but more importantly puts the IVC right where it needs to be with the higher compression (12:1) of the blue printed engine. Simple stuff, but it makes HUGE gains!

(Note: to read more about the IVC & compression, do a search on "comression mapping" on this forum. Some good info posted there.)

[John Brown]

[ QUOTE ]
Just look at the killer "L89" Nova run by the Brewers from Georgia. 12's on polyglass with a Turbo 400 tranny. Stock? Ummm errrr....not really...stock appearing? Yes.

[/ QUOTE ]


If you liked Brewers Nova, you just gotta see what Terry Penningtons Orange 69 ZL-1 clone (S/A) does on white lettered Polys. How about 11.30's ! [img]/ubbthreads/images/graemlins/[/img]

[Chevy454]

I was admittedly one of the ones who said "no way" when Brewer was dropping low-mid 12s on people. Heck, I ran Phil in my first Pure Stock event ever and he dropped a 12.5 on me. I immediately said "no way", as I was running a 427 Camaro and was only running low 13s...of course, I didn't know jack squat about tuning a car, but I figured since I had a 427 and he had a 396 that I should be able to take him. O'contrare mon frere! Granted, he had his engine set back and was admittedly "stock appearing", but my eyes have since been opened, if only a wee bit.

So, we built an engine the way Tonowanda would have back in '69, with the specs way off of what was advertised, just to see what would happen. Well, I've since gone 12.7s@108 with it...if I could hook it, it's got .6s in it, no doubt in my mind. And mind you, this is with 10.2:1 compression, the stock cam put in as original (not retarded), and a heavy automatic Camaro (3700 with me in the seat). That particular engine put up 425+ on the dyno through the manifolds, and I feel better about the timing/jetting I have now than when it spun up the dyno. We basically did it to see if it was possible, and it is, and then some. Pete tried to tell us, but we're Missourians, so you gotta "Show-Me" it can happen.

A lot of what works on your typical "race engine" won't work for what we (Pure Stock guys) do. We're running stock manifolds and 2.5" pipes, so big flow numbers only hurt us because we can't get rid of it. And since we're running the stock cam, heavy duty springs only hurt the cam and add unneeded friction. That's why cam timing and distributor timing are so crucial...we try to sacrifice the bottom end just so we can get rolling and bring it back in on the big end. It's definitely a different mind set, and most engine builders can't comprehend it...I know mine sure has a hard time!

Pete has gone 12.0s in his Pure Stock ZL-1 Camaro, and I watched him put that thing back together at the Certified Stock tech, and you'd be amazed at how tame that engine is. And like John said, Terry's car is a freakin' animal!

[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]