Well, it seems like it's been forever, but I finally got it together enough to get it to the engine dyno. It's about time!
CNN version.......

825.1 HP@ 7400 rpm!!


It was a last minute deal to get it on dyno this week. My regular guys had theirs tied up developing their new race motor, but they set me up with one of their buddy's shop a few miles away from them. They recommended them because they have done literal back to back tests on an engine 3 hours apart to verify accuracy of the two dyno's and found only a 2 HP difference! That's pretty close!

I worked on it 'till 12:30 the night before getting it off test stand, back on engine stand to set valves, change oil and generally look over before I loaded it into pickup.

Met at shop at 8am and we had it installed on dyno in no time and running. The initial setup had it running with my 'ole single point distributor. I borrowed the "house dist" from my regular place to use. The new guy wanted to see what it would do with points so we gave it a try. I had no idea we were going to use them so I didn't even look at the dist to check points, dwell or anything. They are over 5 years old!

We warmed her up and let it fly. The guy asked me what RPM I figured it would peak at. Since the last version peaked at 6200 rpm or so I figured for sure it would be done by 7000, especially since most everyone I know with deals like this are too. He set it for 6500 RPM for first try.

PULL #1-My heart nearly stopped when it showed only 716HP @6500rpm. I was thinking I had created a stone!! He said don't worry because it needed to break in more. We let it run for awhile with light load to help seat things more.

PULL #2- No changes....set it for 6800 rpm because it seemed to still be climbing at 6500rpm. It made 752.9 HP!! OK, that's a little better, but it was still climbing. It also showed to be a little rich.

PULL #3- Dropped 2 jet sizes in each end of carb. Set it for 7000 rpm. Climbed to 756.7 but it started breaking up a little at the top end.

PULL #4 - This sucker was pulling 2" of vacuum at the top end at WFO throttle even with the 1050 Dominator. I had access to "mega Dominator" carb from a friend. This is literally off of a very well known Pro Stock racer's car that the Pro Stock racer (must remain anonymous!) set up as a single four carb. I'm talking about a $5000 carb! I went to talk him into letting me borrow it for a few pulls. THAT was some talking, and he is a very nice and trusting guy! Interestingly he told me he didn't think it would help me any. Since it was still climbing in RPM and HP, yet remaining pretty flat overall, he felt my real restriction was in the intake manifold considering my recent head work. Now you have to understand, my old intake was a VERY small (relatively) TEAM G and the new one is about the biggest thing made out there without going to a sheetmetal one. It's an Edelbrock Super Victor. I spent probably 18-20 hours on it massaging/porting/matching it. He said I didn't remove enough metal! But I took the carb and installed it anyway. Guess what?...he was right! This thing literally flows in the 1400 cfm range and it picked up about 6-8 hp overall and it still showed 1.6-1.8" vacuum at high rpm. But it was a fantastic carb, looking at the BSFC numbers. It lost very little down low and pulled great. OK,that didn't work......

PULL #5- Kicked the RPM a little higher to see what would happen. It still wanted to climb. This is where my 'ole points decided to call it quits. They started bouncing in the 6900-7100 range. Made 767.8@ 7000 rpm, but fell to 729.9 by 7100 rpm when points bounced! Man, wish I had a new set to see what would have happened!

PULL#6- Dropped in the "house dist". It's a plain 'ole Vette tach drive with an electronic conversion kit in it. No other changes....pulled it to 7000 rpm. It made 778.1!!!! Sounded great....no miss! Made a couple of pulls to check timing changes. No increase noted.

PULL #7- Reinstalled my homebuilt 1050 Dominator. and decided to let her rev a little higher. Pulled great and made 792.8 HP at 7100 rpm! Power started dropping at this point rapidly and was down to 771.3@ 7300 rpm. Hmmmmm... Thought I might have hit the peak......

PULL#8- Trying to figure some way to get some more airflow. It was pulling 1.9-2.0" again and just seemed to be running out of air. Not sure how I'm going to make it fit under the hood, but I installed a 1" open carb spacer. No other changes. Man, THAT was great. Took it to 7200 rpm and recorded 809.6hp!!! Overall it was a great improvement, and there were places in the run where it helped almost 25 HP! Wish I'd have had a 2" one to try!

PULL#9- No changes. At this point it is still making 601 ft lbs of TQ at 7000 rpm. It is only dropping about 2-5 ftlbs per 100 rpm. That is amazing at this rpm for this big of an engine. It was just hanging in there! The way HP works is that if you can hang onto TQ as RPM climbs, you will continue to increase HP readings. At least until the rods exit the block! So we pulled it to 7400 rpm. It made 825.1 HP and 585.6 ft lbs!! At this rate. I'm not sure what RPM the HP is going to peak at. At 7300 rpm it was still at 589.1 ft lbs.

WHEW...took a break right about there and thought about things for awhile. We looked at all the data and noticed lots of interesting things. I had a buddy there watching and he said he was too stresed out watching it and we ought o stop there while we were ahead!

1) My friend was right....it needs a larger intake or a huge spacer to increase plenum volume. It was still pulling 1.8-1.9"of vacuum at high rpm. Big carb didn't help much, my carb was not that much of a restriction. In fact my homebuilt 1050 cfm piece was actually flowing 1173 cfm!!

2) Spacer really helped a lot. We had temp probes in all eight header tubes and without the spacer there was almost a 300* temp difference from the highest to the lowest cylinder! That's a mixture issue. Don't assume the cooler temps are bad. In fact, as efficiency goes up, you will see cooler cylinder temps because more heat is being turned into mechanical force and not going out exhaust pipe. Just the addition of the spacer brought temps within 110* of each other! Amazing and something you would never know without having test equipment. End result was my intake work actually flowed well, but at these speeds fuel just could not make the turn from venturis into port without slamming into plenum floor. The next step could be to do a little stagger jetting to really even out temps, but around a 100* spread is pretty good under full load!

3) It wasn't sensitive to timing. Before heads were reworked, a move from 36* to 39* was worth around 17 HP I believe. This time there was negligible change from 36-40*.

4) It has turned out to be pretty darn efficient. It measured 119% Volumetric efficiency. So much for that 80 % deal in those carb formulas!!

PULL #10- We made one last pull. We installed a set of generic 2" headers replacing the 2 1/4" dyno headers (mine from the car wouldn't clear the dyno stand), removed the spacer from under carb and put it in "worst case scenario" to see how bad it would be. The day was almost over and I didn't have time to run all these changes separately. It still made 781.3 @ 7100 rpm. That was actually pretty encouraging. It was only about 11HP down from #7 pull, that was essentially the same setup with the big headers. Of course I'm sure the engine was a little more "broken in" by now too! The interesting part was that up to about 6400 rpm, the 2" headers just killed the 2 1/4" ones!! I'm talking 40-60HP down in the 4500-5000 range and tapering to the 20 hp range up to 6400rpm or so. After that, it was like I had flipped a switch and it steadlily progressed to where the large headers were up 20 or so until the airflow started choking without the spacer again. Looks like a good 2 1/8" tube will be about right for it.

It was a great day overall though!

1) I would have loved to play with Cam timing some, but I am using a one piece cover and that eats up lots of dyno time. I might advance it a little before I install it in the car to make it a little less of an "RPM Queen".

2) My plan for next year is to build headers, so this gives me some data to work with.

3) Gotta figure out how to get a spacer under a stock looking Vette hood!

4) Am I finally going to have to break down and get rid of points? I dunno..maybe I'll just buy a new set!

5) It idles pretty decent. I'll work out carb final tune in the car, but it holds around 6-8" of vacuum depending on idle speed and I can make that pretty driveable I'm sure.

6) All runs were made on pump gas.

7) No vacuum pump system, just breathers. Pumps are typically worth 20-25 HP.

7) I'm very impressed with the results my head porter pulled off. It took a long time as he worked to develop a port, but it shows it paid off. To still be climbing RPM with this size cam in a motor this big is a testament to his work. Just to give you an idea, he did the angle milling after he did initial port work, and though that usually helps flow, it killed mine. Without a flowbench you would never know it. He spent a week reworking port shape to get it back, plus get back what the angle milling should have automatically given it plus a little more. This is a guy that Lingenfelter has paid to develop a port for his CNC program!

8) Just to put it all in persective. My first version of this deal made 732 HP at 6200 rpm and 678 ft lbs at 4900 rpm. As RPM climbed, it rapidly fell off to the point it was down to 591 HP at 7000 rpm.

THIS version peaked at 663 ft lbs (large headers- 667 ft lbs w/small ones) at 5300 rpm. BUT it is up 234 hp at it's peak!!! I'll gladly give up 15 ft lbs for 234 HP!!!!

THIS IS GOING TO BE FUN!!!

JIM

 

Come on man, I'm reading about 1000 and 911 horsepower big blocks in the magazines, what's your problem? :D

Better update your sig, still says six hundred-some horsepower.


[Modified by Schmucker, 1:41 AM 6/28/2003]

 

Buirning the midnight oil Jim? :D Those are some impressive numbers. Wish I had friends like yours. :yesnod:

Got any pics of that Monster?


[Modified by 1970 Stingray, 2:47 AM 6/28/2003]

 

Yeah I guess I need to take my motor to California for some "magic" numbers!

My regular machine shop has a race car that is regularly the #1 qualifier at events, is in the magazines all the time etc.

It uses a 477" motor based on a 4.500 bore size. I told him about that article and told him he was working way too hard, 'cause he could just trot out there and let those guys bolt one together. Not sure if I can type here his exact words, or one of the other guys that works there who knows those guys.

But the overview was:

"Let's see, we have bigger bore, shorter stroke, more compression, more cam, seriously reworked heads and intake on flowbench, (they used out of the box stuff) 5 years of track and dyno time developing the combo and make about the same HP?" (Oh yeah, and Westech does it at 1000 rpm lower!!)

He said he would believe it if their 900 Hp motor outran his 900 hp motor. Or if they made 900 hp on HIS dyno. Or they put their motor in his car. Or if they just wanted to meet at the next race and run 'em!

Did you notice last time how all those 550-600 hp smallblocks gained 30-50 HPjust by traveling to the West Coast to the same dyno shop from the East coast and Central U.S.?

I also recently heard of a big name East Coast 850 HP motor making around 680 on a local dyno. And then the new replacement one made right at 700!

I saw a big name Canadian "9 sec LS1 stroker motor" make 425 hp on the local dyno too.

The general group consensus was they need to have a lesson in dyno calibration!!

But it doesn't matter in the comparison tests really as long as they are all run on the same dyno. You can still draw good valid data.


JIM

 

Jim,

Sounds like a very fun and successful day of experimentation!! It does not surprise me at all that the 2" headers made more power under 6k rpm. That's why I'm not concerned about slightly dimpling my 2.25" sidemounts a bit on my very mild motor. I don't think it will hurt me at all.

I will also be interested to see the difference in HP/TQ b/w the engine dyno and the chassis dyno...assuming you take it somewhere for fun once you get everything in the car and running.

Are you not going to have any hood clearance issues with the new manifold and now a spacer, too?

Here's to continued success with your project!! :cheers:

 

Congrats Jim! I know you've worked hard on this motor, and the numbers that you have to back it up are proof of your hard work. So when do you plan on taking it to the track :) .

Once again congrats on the great motor Jim.

 

Wow, that is really awesome. Some of us Houston older vette owners (meaning the car ;) ) need to get together. I've just gotten mine running again, there is a guy down the street that has a '65 (he's putting a HP smallbock in it soon), and a friend that has a 72 BB and we all need to get together sometime. The guy with the 72 is trying to start a club and make things a little more interesting for us musclecar nuts.

Nice runs and great work!!!

 

This made me laugh. You were really upset with a measly 716HP. :)

Thanks for sharing. :cheers:

 

Great numbers! Have you considered cutting the bottom off the manifold and extending the plenum downward into the lifter valley? Would give you the needed plenum volume while fitting under the hood.

 

Thanks guys!

It really feels good to have it running well after all this time. It's been a long year!

I gotta work on the intake issue. I actually considered the very thing you mentioned Marcus. I was thinking of some sort of V plenum like the sheetmetal tunnel ram guys use. The tricky part would be that I would really need more flowbench and dyno time to work out the flow properly. You gotta figure Edelbrock spent tons of time developing that dude considering they were up against the Dart that has been the std. forever. To keep fuel able to turn I'll have to use a V floor or shorten runners, which considering my RPM probably isn't going the right direction. Maybe I need to check the used market for a Hogan sheetmetal one huh? Jeez.....does it ever end???

If nothing else, I can cheat at the track and use the spacer with some rear hood latch extensions if necessary. I'm going to work on the whole concept as soon as I get it installed. Might have to pull it and work on it some more!

Still hard to believe that intake is much of a restriction, but I guess numbers don't lie. I also don't want to get too hung up in chasing dyno numbers right now. There is much more to getting the car to be quick than peak numbers. The fact that I have less midrange TQ (just a little) and TONS more high rpm power might just be the ticket to getting it hooked up and down the track.

I know for a fact that I could barely hook up what I had before. So any more in the lower end range is useless. But a couple of hundred more at the top is possibly going to be just right!


There's the old saying..."You don't race dyno's or flowbenches". I think I'll concentrate on making the whole combo work with what I've created. There's going to be a ton of work making it all perform right.


Thanks again guys, I really appreciate all the feedback!

JIM

 

damn. what the hell are you gonna do with all that power :lol:

 

I do! :D :D Maybe that's why I don't get out too often...

Steve

 

That Westech dyno is WAY soft. Dave Storlein who ended up 2nd to Joe Sherman had this to say about the Westech dyno: "If that dyno in CA looks to give us that much more power like we think, you tell Sherman to get his butt out of the way". To give you an idea of the the gain going from the Comp Cams dyno to the Westech dyno, Storlein's engine went from a combined total score (average torque & HP 3000 - 6500) of 841.2 on the Comp dyno to 900.2 on the Westech dyno. Keep in mind those figures are based on averages so his peak HP gain was substantial.

Jim, send your engine to Westech and you can have a "certifed" N/A pump gas 900 HP engine!

Take care,

Mark

 

THAT'S what I'll do!!! I wonder what the shipping is? ;)

I wonder if I could just get them to "re-correct" MY dyno sheets to some new numbers??? All it takes is a couple of variables right?

I guess when I get a pass on it I'll know for sure....MPH don't lie!


And yes......Steve.....you gotta get out more!!! :)
You're the dyno king...I would love to have one to play with too. I'd be addicted also! You probably have more dyno experience than half the shop owners out there. I should have had you come down and help tune that dude on the dyno with me!


JIM

 

:eek: :eek: That's some awsome power :eek: :eek: :cool: :cool:

Wanna race?? :jester :jester

 

Jim, the power of that engine is absolutely incredible! I think you're gonna need BIG tires. Do you think you can maintain that type of power level through any type of full exhaust?

Thanks for putting it into words so that we can all share the experience. That's gotta be as much work as building the engine! :lol: