ZL1powr

This is a little long winded but I think there is some good data to share.

Despite the storms Saturday evening and the roasting heat and humidity I had a great time at corvettes at Carlisle. I brought two cars to the fun display my 65 and my 71. I worked late nights last week finishing the 565 install in the 71. I only had time to put about 20 miles on it before the show so I towed both cars to the fair grounds with two trips up on Thursday and two trips home on Sunday.

I entered the 71 in the dyno challenge sponsored by Corvette Enthusiasts magazine on Saturday morning and my numbers held as highest for the day and highest for the week end until one of the last runs on Saturday when a C5 posted a 600+ HP to my 580. Our torque’s were similar if my memory serves me (in the 640’s). I didn’t see the C5 so I don’t know what it was running but I have to believe it was using some type of power adder.

My numbers were close to what I expected with the Hooker side pipes compared to previous runs on the engine dyno with dyno headers. The Hookers change the shape of the curve by increasing mid range torque and flattening out (lowering) the top end HP. That is what I saw on the engine dyno with my previous 489 motor and also what I observed comparing these chassis dyno results with previous engine dyno results for the 565.

The runs on Saturday were with the Hooker header side pipes with Hooker Max Flow inserts. I thought it would be interesting to do some runs with open headers so I came back on Sunday morning and removed my side pipes for another try. Any of you on the fair grounds on Sunday morning probably heard it.

The peek HP only went up by 7 HP to 587 and the torque peek was the same at 641. The curves are identical and lay on top of each other. The 7 HP advantage at peek was in the noise level. The average HP from 3000 to 6200 was up by 2 hp and the average torque over that range was down by 2 ft-lbs, so the Hooker Max Flow inserts had essentially no impact. The A/F was showing to be lean at the top end but I don’t know if it was an accurate reading since they were having trouble keeping the O2 probe in place. As you can see in the video below the exhaust flow tried to blow the O2 probe out of the pipe on the open header runs. It also appeared to be on the rich side with a little bit of black smoke so I am not sure which way to go yet.

I was also concerned that my HP might be affected by constricted flow between the carburetor and the hood so I made a run with the hood propped slightly open. The engine responded with a loss of 15 HP across the RPM range. I suspect that the carb was now able to pull in hot air from the engine compartment and off the radiator instead cooler air through the cowl induction. I also am concerned that my Malory 110 electric pump and 3/8” fuel line at 7 psi may not be adequate for this engine. I have some detective work to do to determine if factors other than the headers contributed to the flat HP curve above the torque peek.

That being said I was still happy with the results. I got a call on Sunday from Corvette Enthusiast magazine and they said I had the highest numbers on Sunday. I believe they were 2nd highest overall behind the C5 that beat me on Saturday. I also suspect they were the highest “no power adder” numbers but I can’t confirm it because I didn’t get a look at the C5. I won $75 to pay for the dyno run, a t-shirt, and a 1-year subscription to Corvette Enthusiast from Corvette Enthusiast Magazine; a $100 gift certificate and a hat from SLP; a $50 gift certificate from Year One and a case of Royal Purple Oil.

A video of a couple of the runs is attached for your listening enjoyment. On the first run it sounded to me like the wheels broke traction momentarily and then hooked back up. That was the only run that sounded like that. I can’t post the actual curves until later in the week because I forgot to bring them with me to work in Baltimore and they are at home in Keyser WV.

I now have in excess of 40 dyno pulls on this engine and I am still learning good info to help with the tune.

Video of dyno runs

maddmickey

I am new to corvetts, will they handle that much hp or do you have to beef up everything? (rear diff. ect.)

PRNDL

Jim, that is fantastic! Congrats

Your old engine wasn't all that bad either. What did you do with it?

Did you get the 65 on the dyno? It has a big blower on it, doesn't it?

Any plans to take the 71 with new motor to the dragstrip? You might need a parachute!

Did you build this engine? What block did you use?


(video link doesn't work)

ZL1powr

It is fine as long as it dosn't hook up but requires beefing up if you plan on running sticky tires at the track. I have Tom's 12 bolt rear end set up to install (just arrived) that should hold up well and the TKO 600 transmission is very strong.

ZL1powr

The old engine is going in a 69 that I am restoring. The original engine has a cracked block. I didn't put the blown 65 on the dyno. I plan to take the 71 to the strip in Sept. A few of us have Pittsburgh Raceway Park leased for the day. Yes I did build this motor, there were a couple of earlier threads on build:

http://forums.corvetteforum.com/show....php?t=1764130

http://forums.corvetteforum.com/show....php?t=1765670

By the way, did you make it to Carlisle this year?

427Hotrod

Well, first....Congratulations on the Dyno Challenge win!!

2nd- I really appreciate guys who *let it all hang out* and are willing to test and beat on their stuff to see what it really does...and keep refining it to improve it. To me,,,that is just flat fun stuff!

3rd- I also applaud you for letting us all in on your buildup, your engine dyno testing and now chassis dyno testing. You write it all so that it's almost like we were there! Thanks!


Now...let's get that thing out to the track and REALLY have some fun! How does it feel compared to the old 496? Or was it a 489? Anyway.....do you get the sensation that it *wants* to rev and keep going like 565's are known for as compared to the smaller bore motor?

Anything you think you'd change at this point? I know you said manners seemed better....how's initial drives seem?

That's pretty impressive on the Hookers and inserts. That's almost nothing for a loss when *capped up* in the big scheme of things. Those Hookers have some long tubes...so that will favor that low end stuff...but they are 2-1/8" right? Should breathe fine at higher rpms.

And my gut tells me that C-5 had a little artificial help! As good as LS motors are...it would take a stout one to lay down 600RWHP N/A.

Plus it's fun to *kick it* on the trip home with a *boosted* car. I usually find that a blown car and a N/A car that make similar power..will find the N/A car walking away from the boosted one. Seems like boost *likes* chassis dyno's,,but it doesn't always match up later on.

Also....we ought to say thanks to Corvette Enthusiast..those guys really support all of us here on the Forum! Thanks Andy!

Again Congratulations on a great win and a great car!



JIM

Crab

[QUOTE=ZL1powr;1561714946]The old engine is going in a 69 that I am restoring. The original engine has a cracked block. I didn't put the blown 65 on the dyno. I plan to take the 71 to the strip in Sept. A few of us have Pittsburgh Raceway Park leased for the day.



What date are you going to be at Pittsburgh Raceway and will it be open to the public? I'd like to watch

82MDVette

I saw your Vette on Sunday at the Fun Display and had to do a double take as to why there were no sidepipes on the car. I pointed this out to my Buddy and he joked "maybe the storms ripped them off last night".

gkull

Great job on some serious N/A HP

That C-5 is probably like this local guy that has a license plate that says 620 RWHP. I'd seen him a couple of times over the years and finally managed to track him down. He is using a 3.875 stroker 400 block to get 421 ci and a big belt driven centrifical supercharger. This is all on pump gas. With racing fuel he could change the pulleys, But he is worried about what the 6 speed and rear end can take without blowing up

ZL1powr

Jim .... Thanks. I can't wait to get it to the track. The diference between this motor and the 489 is just incredible. It flat wants to jump out from under me in any gear. You can really feel the difference in torque. I was also plesently surprised at how crisp the throttle is with the single plain manifold and fairly large heads.

The Hookers are 2 1/8 primaries but the long tubes seem to knock a little over 400 rpm off the HP peek and about the same off the torque peek. When I tested the 489 on the engine dyno with the Hooker side pipes I saw about a 15 HP reduction and picked up a ton of torque.

I second your thanks to Corvette Enthusiast Magazine.....Jim

ZL1powr

The spectator area will be open to the publc. The date is 9/21.

ZL1powr

82MDVette .... My car was there durring the storm. When I arrived there was a large mark on the passinger side rear fender. At first I thought it had been hit by something but when I looked close it turned out to be a piece of paint pealed from someone elses car that had blown against mine and stuck. I was lucky and had no damage.

You should have stopped by and said high.

gkull ... Thanks. I am very happy with the engine.

82MDVette

When we walked by there was no one around the car. Definitely next year!

Z-man

On a dyno like that, how do they do it? Is a pull done in one gear? If so, which gear? Do you drive your own car?

tshort

WOW! Talk about a sleeper!!! Especially with the BFG's and stock body and still fitting it all under the L-88 hood. Congratulations. Make sure to let us know how it goes at the track and make sure to get some pics and videos.

ZL1powr

Z-man .... They run it in the gear that provides a 1:1 ratio at the trany output. In the case of my 5 speed they ran in fourth (would be the same for a muncie). They drive the car and control the dyno computer from a consol right outside the drivers window. You can sit with them in the car. When you sign up you specify the max RPM you want them to run and sign a waver that says if it breaks it is your problem.

tshort ... Thanks. I plan to get some vidio coverage when I take it to the track.

82MDVette .... Next year

Iliad

Jim, Congrats on making it to Carlisle with your new motor.

69ttop502

Great results and real sorry I missed you at Carlisle as we left on Saturday. Sounds like a great motor. It is still hard for me to believe that a 2.5 inch muffler is not a restriction on that motor. Really goes against everything I have seen on the dyno with my car. Anyway, congrats and will look forward to seeing your track results. Any idea what your car weighs?

Bill

Red73Vert

Awesome runs!!!!

I loved the video! Thanks for sharing.
I was there on Saturday and saw the white C5 run. You were right. If I remember correctly he was running a large Procharger supercharger and put down 633HP to the wheels. The car could have been called "streetable" (idle was not too choppy), but he was definitely setup for the strip with skinnies upfront and drag radials in the back.

Congratulations on some great runs and a well put together combination!!!

ZL1powr

Red73Vert, 69ttop502 and Iliad .... thanks for the complements.

69ttop502 ....

The fact that the inserts did not have any affect on the results is also a surprise to me but exactly the same thing happened on the engine dyno with my previous engine. The muffler is basically a smooth tube with holes in it and with a smooth transition into the tube so it appears to be very efficient.

The car weighs 3260.