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

 

:thumbs:
Very interesting!
The spacer appears to do 2 things, even up mixture and increase volume. If you cant fit it under the hood, work on stagger jetting and get most of the HP without the height.
Where are you measuring vacuum? if you can get a reading at the end of the port, close to the head, it should tell how much restriction the manifold is.
Back in the 70's i took apart an old set of points, and used the spring to double up, and get over 7000. Now i use pertronix 1181 w/accell super coil w/ 0.8 ohm ballast resistor. You can still use the tach drive and switch back to points in an emergency. :cool:


[Modified by Matt Gruber, 8:26 AM 6/28/2003]

 

:eek:

 

That's gotta feel like one BIG accomplishment .. Great HP numbers .. !! .. I didn't know a BB could be spun up that high in the rpm range ..

 

YOW!!
:eek: :cool: :cool: :eek:

 

I had no idea that a big block could spin that high either. My goodness. Very impressive.

:eek: :eek: :eek:

 

Great effort Jim!! I didn't know BB's had this kind of potential in them.

That's Winston Cup motor territory!!!

:cheers:

 

I can't imagine HP readings in that range :eek: :eek:
I've driven and raced cars in the 400+ HP range but this blows me away!!
Congratulations :thumbs: :thumbs:

 

Thanks guys!!

Remember...the only thing better than a small block at 7000 rpm is a REALLY big block at 7500 rpm!!

JIM