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Chevy454
02-26-2001, 07:46 PM
I was just thumbing thru my MCR and noticed the dyno test they did on one of Peter Simpson's COPO engines...what are everyone's thoughts on the outcome?

I was surprised to see that changing the valve lash changed the torque amount the way that it did. That is one of the things that I have began to mess with more and more in the past year or so, and according to that article, my "lashing" is justified!

Belair62
02-27-2001, 12:06 AM
I was surprised to see the engine needed carb spacers to get close to the advertised HP figure. I think they wound up with a 2inch spacer.

COPO
02-27-2001, 12:30 AM
That surprised me too and was a bit disappointing. The LS-6 they tested came right in at the factory rating of 450 hp, so I expected the same from the L-72.

I can tell "seat of the pants" that the valve lash makes a difference, I too was surprised it was that large.

JoeC
02-27-2001, 02:38 PM
The article states that they experimented with total timing from 36 deg to 44 deg and the dyno numbers did not change significantly. I would think that an 8 deg change in total timing would have shown some differance.

Keith Tedford
02-27-2001, 09:53 PM
I was surprised that the engine made advertised horsepower with the stock exhaust manifolds. These pieces were a bottle neck. The value of fine tuning was also quite obvious. It would be interesting to see a run on the engine with headers. You aren't going to be driving on 112 octane gas all the time so how would the engine run on 92? As for the 2" spacer, it is not going to fit under a stock '69 Chevelle hood. The breather almost touches now.

[Edited by Keith Tedford (02-27-2001 at 04:53 PM).]

COPO PETE
04-14-2001, 10:09 PM
Sorry to drag up an old thread but I found some of the comments very interesting on this topic. The motor did make 420 honest horse without any spacers and before fooling with the lash. All dyno's are different, they are not calibrated like scales and federally watched. When my engine builder asked what dyno I wanted to use, he asked if I wanted to use a happy dyno or a sad dyno. The happy one would show 20 more horse he said. We chose the sad dyno because like he said, "when you have 420 horse, you know it's a true 420 horse. Depending on altitide, temp, and dyno, your results can be + or - 15 horse. The dyno is simply a tool for measuring changes which it does well. So while the paper out of the dyno is very interesting, the piece of paper that matters is the one at the end of the return road. That piece of paper said 12.69 @ 110 which was on F70-14 polyglas with a stock GM converter, and a single cross flow muffler. Also no spacer was used. The 454 MCR dyno'd did not have a stock GM cam and was run with 2" headers not manifolds. Have a great day and sorry to bring up an old thread but I'm new around here. http://www.yenko.net/ubb/smilies/images/icons/smile.gif http://www.yenko.net/ubb/smilies/images/icons/laugh.gif

YENKO DEUCE REGISTRY
04-16-2001, 01:42 PM
Pete;
I agree with you, the real power number is on the E.T. slip not the dyno printout. Impressive numbers at the drags from a stocker, congrats.

When will we see the COPO Nova run again?
Marlin

COPO PETE
04-17-2001, 12:34 AM
Marlin! Man, I hav'nt seen you forever! Did you get your Yenko done yet. Remember put the stock cam in, ask Niel about that advice.The COPO will be out sometime but I'm not sure when. Hope to see you this Sept. and once again I'll bring the beer. http://www.yenko.net/ubb/smilies/images/icons/smile.gif http://www.yenko.net/ubb/smilies/images/icons/smile.gif http://www.yenko.net/ubb/smilies/images/icons/laugh.gif

YENKO DEUCE REGISTRY
04-17-2001, 02:30 PM
Pete;
My car is coming along, I hope to have it ready for the new All GM Show at Carlisle in June, 2001. I put the right cam in it, and the 11.0:1's, hope to hear it running by early next month. Some pics are attached, I plan on running whitewalls at the concourse shows. I only have two of the Atlas wheels, and am looking for another pair - anyone??
M

http://albums.photopoint.com/j/View?u=378134&a=2796933&p=46709429&Sequence=0&res=high

http://albums.photopoint.com/j/View?u=378134&a=2796933&p=46709431&Sequence=0&res=high

http://albums.photopoint.com/j/View?u=378134&a=2796933&p=46709432&Sequence=0&res=high

Chevy454
04-17-2001, 03:24 PM
M:

Car looks good! If you could get the car to look like that on the launch, you would have one heck of a 60 foot time! What a launch http://www.yenko.net/ubb/smilies/images/icons/wink.gif. Any chance of you making to Michigan this year? Is Neil gonna be there again?

Peter:

I'm hoping to rebuild my engine and see if I can get some dyno time to break it in a try a few things. Question: I need to curve my distributor...how soon does it need to be all in? 2,500? Sooner? Later?

COPO PETE
04-18-2001, 11:50 PM
CHEVY454; In my cars I run all the timing in at 2500 rpm. 20 initial and 36 total.Good luck. Let me know what your dyno says! http://www.yenko.net/ubb/smilies/images/icons/wink.gif

Marlin; Cars looks like it's coming right along. I love the shot with the old 1/4's hanging in the background. Good luck to you as well.
Peter

69yenkoman
04-22-2001, 08:18 PM
Marlin:

Your car is coming along good. I like the old 1/4's haning in the background as well. Looks like you are doing a super job.:burnout
:

YENKO DEUCE REGISTRY
04-23-2001, 02:26 PM
Thanks for the kudos, I can't wait to drive it. I also saved the deck lid and tailight panel, and plan on hanging them together in my garage at home. Brian Henderson has an original '69 Yenko Camaro 1/4 hanging in his shop as well, they look cool!
M

Chevy454
09-06-2001, 01:57 PM
Well, guys, it's final: we put the L-72 on the dyno yesterday, and it spun it up to the tune of 420hp@5,600. This was through the exhaust manifolds, of course, but we were more after a good "break in" for the engine, and to try so different settings (jetting, timing, lash, etc.). Needless to say, we learned a LOT! The settings we ended with (lash=24,24 jets=78,84 timing=40 degrees) are a little bit different than what Pete used, but they worked the best for us, so we stuck with 'em. Now, I had better go see about getting that thing between the frame rails...

JoeC
09-06-2001, 02:11 PM
WOW 420 HP with exhaust manifolds. Sounds great. Did it have mufflers hooked up also?

Chevy454
09-06-2001, 02:30 PM
No, no mufflers, but the "dyno guy" said that a good set of mufflers (like a DynoMax) wouldn't change that much, except raise the torque a shade.

What we did was tune for a broad power curve, versus a higher peak. When we found that, we stuck with it. From 5,100-6,000 it was making 400hp or more, and was in the 416hp-420hp range all the way from 5500-6000. 6000rpm was about the most the engine seemed to like to run...now the only problem is keeping dad from spinning it over 7k!

COPO PETE
09-06-2001, 02:57 PM
Congrats Rob....12.6 here you come!!!!!!!! http://www.yenko.net/ubb/smilies/images/icons/laugh.gif
Peter

Rowdy Rat
09-06-2001, 03:25 PM
Rob,

Well done!

I'll be looking forward to see how you do at the PSMCDR this year.

By the way, did you decide to use the 291s with the big exhaust valves or did you go with the 840s?

Regards,

Stan Falenski

Casey Marks
09-06-2001, 04:34 PM
GOOD DEAL !!!

Sounds like it's gonna be one bad hombre' !!!

Look forward to seeing you and the car in a week !

Chevy454
09-06-2001, 04:54 PM
Pete:

I would be VERY happy with 12s, and I honestly feel anything better than low 13s (from my car) is GRAVY.

Stan:

Well, I unfortunately(!) went with the 291s. I talked it over with several people (even Pete and JJ!), and they all gave me the thumbs up, as they are legal. I say "unfortunately", because the set of 840s that I ended up with need ZERO work, and would have even been cheaper to build than the 291s I used. But, I had to keep the 840s so they could be documented...kind of a shame! Colvin is supposed to be checking for some paperwork, but as of yet, all I have is the info from his book and info from talking with him and others on the phone. So far, the scenario I went into detail about in another thread seems viable, and isn't as far fetched as I had originally thought.

This engine turned out really well, and is about as close to factory as I could have made it. It would have been done about 2 months ago if I had not been worried about factory specs! For instance, the stacked height+gasket thickness is equal to that of what the factory would have been. The only difference is the .030 overbore, which could not be avoided due to a couple of bad cylinders. I had to shave the heads .010 (another extra thing due to NOT being able to use my 840s!), but when I cc'ed them, they came out big (as expected). Like around 111cc average, where they are supposed to 108cc. Well within what you could have gotten straight from the factory. When I plug all of the #s into the compression calculator, I come up with 10.9+, so it is almost dead on the AMA spec. Our next engine may take these specs to their extreme and see what happens http://www.yenko.net/ubb/smilies/images/icons/wink.gif!

[Edited by Chevy454 (09-06-2001 at 11:54 AM).]

Mr70
09-07-2001, 05:48 AM
Very http://www.yenko.net/ubb/smilies/images/icons/cool.gifRob.
I and Steven J and also waiting to see how you perform at the PSMCDR soon.
Glad the heads worked out.
Hello 12's http://www.yenko.net/ubb/smilies/burnout.gif

Chevy454
06-04-2002, 01:47 AM
Sorry to dig this up, but I thought I would post some of my results, in case someone ran across this thread and wondered how I did.

At the Pure Stock Drags in Michigan, I was battling a bad set of poly-locks on my rockers, but did manage a couple of 13.0's. A few weeks later, I went to Gateway for a test'n'tune, and ran 12.95@108 on a crappy 2.4x 60' time the first run out of the trailer. Haven't been to a track since.

I'm still running the set of straws (chambered exhaust) on the car, but I am hoping to get a good mandrel 2.5" system and let the 427 breath for a change. We added a rebuilt rear end (went to 4.56s) and also a rebuilt tranny/converter a couple of weeks ago, and it feels a LOT stronger. Hoping to try my luck at Norwalk on the 13th...we'll see what happens!

COPO PETE
06-04-2002, 09:56 PM
I'm thinkin' 12.70's at Norwalk for you Rob. That track is great!!!!!!! If not, I guess I'll have to make a pass for you.....not to put any pressure on ya!
Peter /ubbthreads/images/icons/shocked.gif

Chevy454
06-05-2002, 03:09 AM
I hate to make excuses, but I'm still running that crappy chambered set-up. I tell ya, I was within an inch of ordering up a Flowmaster system yesterday, but I restrained myself. I talked to Pennington and he said the chambered system on his '68 cost him 3 tenths versus the Flowmaster system...it just sucks knowing a TON of my ET is sitting in that friggin' exhaust /ubbthreads/images/icons/frown.gif .

Chevy454
07-17-2002, 04:55 PM
I finally got the "straws" off the Camaro yesterday. Check out the stock chambered tail pipes (which we have been running) compared to a set of 2.5" Flowmaster tail pipes (which everyone else has been running):

http://www.yenko.net/dealers/CHEX1.jpg
http://www.yenko.net/dealers/CHEX2.jpg
http://www.yenko.net/dealers/CHEX3.jpg


A lot of the places in the chambered pieces weren't even 1.5" in diameter! The Flowmaster pipes look like sewer pipe compared to the stock stuff!

Stefano
07-17-2002, 06:12 PM
Rob,
We had a local speed shop dyno test a stock exhaust but for headers on a warmed over 454 LS5 Chevelle vs a 3" inch mandrel system and it meant just over 50 rear wheel HP and 4O foot pounds of torque. Those stock systems with all the crimps and bends are very restrictive.

I installed a set of 3" mandrel bent Torque-Tec pipes with individual 13" Flow Masters on my Ohio COPO Camaro.

The exhaust fits great and sounds even better. It is a bit obnoxious and does set off car alarms on a regular basis.

The car runs a stock L72 +.030 but for L88 spec cam, MSD, Hooker 2" Super Comps. I am taking out the original BE 4.10 rear and swapping in a 4.56 set up.

I have a set of 9" M/T E/T Drag Radials mounted and ready
to go.

I will try to test the set up within the next Couple of weeks.

I just hope the Muncie trans holds up.

John Brown
07-19-2002, 08:55 PM
Stefano
You might want to try this just for laughs. On a DESKTOP DYNO put in the specs for your engine the way it is now, then change the cam specs to that of a stock 396/375 instead of the L-88. You might be suprised! In my experience, power goes up on both ends when used with mufflers. Lots more cranking pressure too!!