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

 

First congrats, for all the guys you have helped on this forum (me included) you deserve your motor to turn out like it did.

I am suprised it wanted to make max power so high in the rpm range, I would have guessed + or - a little around 7000. I would have been cringing in my boots to see my motor at 7400 rpms :eek:

Is the cam in straight up? with your gears it might be a little faster with the cam slightly advanced from where it is now.

Do you plan on putting it on a chassis dyno ?

How soon before it goes to the track

Again Jim, congrats

 

Jim,
All sounds good but looks to be time for another hood huh ? ;)

I suppose you could advance the cam 6 degrees if it will still clear the pistons and play with the valve lash but it appears most of all as you have noted that buddy needs a spacer under the carb if not for max power to get the mix a bit more equal.

Mufflers next uh huh ;) Spintechs and oval 3.5-4.0 inch tubing ?

Glad to see you have it about ready to hit the streets again, have fun!

 

Very impressive! That should get you to the grocery store and back in style.

 

Fantastic! You and Steve Barker have really pushed the envelope on pump gas, N/A big blocks, both producing well over 800 HP (ignoring for the moment the “mere” 500 HP shot of nitrous Steve manages to add).

I know its easy to sit back from a distance and SWAG your power levels, but I’m encouraged I got it right. Here’s a caption from a previous e-mail to you: “I still figure you will end up in the 820 - 830 range.” What I didn’t figure was quite the rpm it took to reach that level!

I also know if there is a way to get that sucker stuffed under a reasonably stock looking hood, you’ll do it! And if you can’t manage the 1” spacer, you could always start whittling away a bit more material from your intake....

I see a big exhaust system upgrade in your future! And a visit from a certain NH couple later this year to experience this first hand.

Congratulations on all your planning and hard work coming to fruition. I’m very interested to learn how this combination compares w/ your previous one in day to day driving, and in WOT situations. Your one-off Dana IRS will certainly get a workout!

Take care,

Mark

 

Incredible, Jim! I can see why it took you so long to finally post your results -you had to compose a book!

It looks as though we have another member of the over 800hp N/A club! Your results are exciting and very interesting. My peak hp of 838.1 w/race gas and 834.2 w/pump gas (you know I just had to get that in) occurred at 6700rpm - significantly less rpm than yours. That is what that bigger cam you have will get you.

Of course, you didn't have a vacuum pump which allowed me to pick up 15hp AND you are only using that 1050 Holley. That carburetor flat amazes me. These types of differences are what makes what we do so fun. How long until you put it on a chassis dyno? Probably not high on your list at the moment.

You have to be extremely happy with the results and really looking forward to getting the motor in your car.

Again, many congratulations - you deserve it after all of your hard work and your ability to put together a phenomenal combination.

Steve

 

Thanks guys, I really appreciate it!

I figure most folks don't get a chance to get their stuff on a dyno. I didn't for many years and would have killed for folks to give me some detailed results of their runs to give me stuff to ponder on. Even if you aren't building stuff this crazy, the details still apply, and hopefully it will help the next guy come up with a killer combo. Why do you think I bug you so much for your results Steve?? Saves me lots of work!! Kind of like your cam positioning..... even with my cam being larger, the intake closing event isn't too far off yours with the wider LSA and retarded setting. I counted on that info to help me determine what I could get by with on pump gas. Your dyno experience paid off for me! I want to be able to help others the way you have.

Mark knows this, but I struggled a long time as to where to put the cam during assembly. Normally a good 2-4 degree advance works well, but since last time around it really needed to get improved top end numbers, I went ahead and installed it essentially straight up. I did that thinking it would help the heads deliver the numbers. I don't think they needed it! Plus this cam is on a tighter LSA, so that usually skews thing a little lower in the RPM range. Hate to think how it would have been with a 114 LSA cam!

And yes, Mark and Steve both hit HP estimates almost dead on! Those guys are good. I was hedging my bets and was going to be happy if it broke 800, but both of them consistently predicted the results. Of course all of us missed how well it would perform at high rpm.

I'm proud of that carb too. I'm telling you, it is nothing special to look at or very trick, but it has always worked extremely well with the mods I've made. Just another case of sticking with what you have and keep working on it 'till it's right. I have quite a few dyno operators testify to how well it acts overall. I still need to add some removable air bleeds, but it does pretty well through the range and drives well too.

Somehow I'll get it all under the hood. One of the problems I had to overcome already in this project was how to fit an Edelbrock Super Victor under there in the first place. One of the things that attracted me to that intake was it's huge plenum volume. I was hoping to get by without spacers. Good thing I didn't go with the smaller Victor as many folks suggested. I'm staying with my original plan that you have to feed these big motors!

Exhaust improvements will have to be the next big thing. Here we go!


JIM

 

This is one of the great things about this forum. You get insight into combinations you may *want* to try, but may not have the means to explore in the detail you desire. Having knowledgeable people like Jim share their thought processes and attendant results allows all of us to make more informed choices on our subsequent build-ups.

I mean how cool is a N/A 800+HP pump gas mid year Corvette???

Congratulations Jim on your amazing result. It was NEVER in doubt!

Take care,

Mark

 

Ok Mark, you are next! How weird will it be to have 3 1967 Corvettes with over 800 NA horsepower?!!

Jim, you are in the spotlight right now. Enjoy it!

Steve