Disappointing day on the dyno

[Brewzer67]

Food for thought just for comparison. The sum of the correct parts = HP. Buddy with 540 BBC 10.25-1 compression Dart pro 1 Fully cnc heads matching intake, Crane .714 bracket roller cam and 950 holley Hp. 825 HP and 725 TQ on engine dyno. He knows motor would make more power with Dominator 4500 series carb but he drives this on the highway to car shows as well as races it. On the Bottle motor made 1125 HP car runs 8.98 in a 3600 lb Nova.

Toss that 850 demon carb on the next swap meet table for one, you should be running an 950 on that motor.

I ran my 426 low deck on the engine dyno after it was built. 383 + 440 Crank = 426. I stayed on the small side with everything, as i was looking for torque and drivability. Eddy rpm performer heads 220 cc intake runner, RPM dual plane intake 10.0-1 compression and lunati solid lifter cam. .544/.566 .241/.253 @ .050. Made 525 hp and 552 tq. motor revs like a small block makes power to 6000 rpm. I am running an AED 750 HOM carb. flows to 830 cfm. Motor only used 630 cfm. The thing is very crisp and has great throttle response. I have had every engine i have built on the Engine dyno, it doesnt lie and you will find your mistakes and miss matched parts pretty fast.

Yep, I know a bigger carb is needed. That is next year. The entire combo is sized to make 800+ hp based on what others have done so far. I have mirrored known builds to make sure I get to the target I am looking for. I just ran out of money before I ran out of needs. I also wanted to drive the car with the 850 for a while before moving up to the bigger carb so I can be better able to decide which I want more, the extra hp or the driveability. I drive 3-4k a year with it so it has to be more than just tolerable to drive. All the pieces are there...almost.

 

[Fisher]

To be honest i am not sure how tolerable an 800 hp motor with solid roller is going to be on the street.

 

[joemish]

Hopefully someone can make me feel better. I took the Coronet to a dyno days event with the new combo and numbers were WAY below what I would have expected (see photo for dyno sheet). The motor in question is my 526" (4.375 x 4.375).
My combo is as follows:
10.78:1 cr
Custom ground 262/[email protected] .715 lift Solid roller bullet cam
TF 270's (ported by Larry Smith - see flow sheet)
Indy 4150 max wedge port single plane intake (also ported by Larry)
850 mighty demon carburetor (factory jetting with 35PV)
Ultimate 8.5" 3800 stall converter just built by Lenny for my combo.

I know I am handicapping the combo with the carb but I did not expect the numbers to be that low. No way would I ever have expected the max torque to be less than 500 ft. Lbs.

The dyno guys said the numbers are low due to the converter and the dyno can't accurately reflect the true numbers because of the high stall. I watched several other vehicles that I know weren't as built as mine laying down better numbers. Can someone educate me on where they think the problem is? I will run a compression check tomorrow to make sure everything is sealing but I don't think that is the issue. I am also surprised by how low the torque peak occurs.

View attachment 523928 View attachment 523929

Maybe you have too much Lenny in the car.

 

[Brewzer67]

Brewzer67, Question,Have you driven the car ? What does the seat of your pants tell you ?

It's been a few years since I last had the car back on the road so I don't know how accurate my seat of the pants meter is but if it is still properly calibrated it is at least as fast as it was when it was running 10.90's with a Racer Brown stx-22 with my old stage 6's. That it why I was dumbfounded by the dyno numbers.

 

[Brewzer67]

To be honest i am not sure how tolerable an 800 hp motor with solid roller is going to be on the street.

So far I don't really have any complaints. It was a little finicky to get the initial carb tune right but other than that it is awesome. Two pumps of the gas and it fires up clean and idles off right away. 30 seconds of idling and I can pull away without having to babysit the throttle to keep it running. It will idle in traffic in 90 degree heat at 180 and not flinch. The overdrive will make the 4.30's liveable on the freeway so it is pretty much just what I was shooting for.

 

[Brewzer67]

Maybe you have too much Lenny in the car.

Lenny didn't think so. His suggestion is the same as several others...take it to the track and see what it does. If we see too much loss through the converter we'll tighten it up a bit. Unfortunately there are too many things to be done yet to be able to get it to the track this year so it will have to wait until spring for the final result.

 

[Fisher]

So far I don't really have any complaints. It was a little finicky to get the initial carb tune right but other than that it is awesome. Two pumps of the gas and it fires up clean and idles off right away. 30 seconds of idling and I can pull away without having to babysit the throttle to keep it running. It will idle in traffic in 90 degree heat at 180 and not flinch. The overdrive will make the 4.30's liveable on the freeway so it is pretty much just what I was shooting for.

Well that sounds great. it seems to have good manors. I need to ask you a question. Do you think the 240 head would of been a better choice over the 270? I would think the 270 would work better on a larger 540-572 cube motor?

 

[1967coronet440]

Well that sounds great. it seems to have good manors. I need to ask you a question. Do you think the 240 head would of been a better choice over the 270? I would think the 270 would work better on a larger 540-572 cube motor?

270 is good for that cam, you’re under carbed and probaly need a different converter.

 

[Fisher]

526 cube 759 Hp dyno run. with specs.
Shady Dell Speed Shop 526 Cubic Inch Mopar being Dyno tested @ Shady Dell. 759 HP @ 6100 RPM, 723 FT LBS Torque @ 4800 RPM. Shady Dell Hand Ported INDY EZ heads, 272/276 @ .050" .728" Lift, 108 LSA Solid Roller camshaft, 10.9:1 Compression, 1050 Dominator, INDY 440 manifold, dyno tested on 92 octane pump gas. 680 FT LBS TQ @ 4000 RPM.....

 

[Brewzer67]

Well that sounds great. it seems to have good manors. I need to ask you a question. Do you think the 240 head would of been a better choice over the 270? I would think the 270 would work better on a larger 540-572 cube motor?

It probably would have made it a little better mannered but I figure when the factory block gives up the ghost my next step up will be an aftermarket block and more cubes. These heads should work with that combo and let me keep the revs a little lower. Plus then with a better block I can look at some sort of power adder with a little more confidence that the block will live. If you knew me you would know that while I'm working in the present, I'm always thinking in the future.

 

[Brewzer67]

526 cube 759 Hp dyno run. with specs.
Shady Dell Speed Shop 526 Cubic Inch Mopar being Dyno tested @ Shady Dell. 759 HP @ 6100 RPM, 723 FT LBS Torque @ 4800 RPM. Shady Dell Hand Ported INDY EZ heads, 272/276 @ .050" .728" Lift, 108 LSA Solid Roller camshaft, 10.9:1 Compression, 1050 Dominator, INDY 440 manifold, dyno tested on 92 octane pump gas. 680 FT LBS TQ @ 4000 RPM.....

That is more like what I am expecting. That is a really similar build. Do you recall what the heads flowed?

 

[Fisher]

The flow numbers were not listed anywhere.

 

[Brewzer67]

The flow numbers were not listed anywhere.

Actually, I'm trying to get here:

http://www.forbbodiesonly.com/moparforum/threads/dyno-day-511-lives-again.134412/

I know I'll need a vacuum pump and probably a few more cubes but that is my goal for this build. AndyF has already got 775 without the porting so I think it might be doable with the extra cubes and airflow I have over his build.

 

[LemonWedge]

My mild little pump gas 451 uses a 1000cfm annular booster HP. Some would say it’s overcarbed, but every aspect of its performance improved over the previous 830 carb, so I’m sticking with what works.

Edit: worth mentioning that it uses an RPM dual plane intake.

 

[zundel]

Years ago....1979? ...my brother's '69 GTX nylon timing gear failed. We had no money, trying to get through Texas Tech paying our own way...He paid a local rebuilder to rebuild the engine...think the builder bored it out .030. something like that. After everything was done, the engine would start and run, everything seemed fine, but nowhere near the power of the stock engine. On the dyno it showed 125 HP at the rear tires?! ...Before, it would set the tires on fire. After the rebuild, barely spin at all. And I have seen that many times when a rebuilt engine with bigger cam, cubes what ever and it just doesn't produce. Very disappointing. Also two engines built to same specs, one produces great power the other one nothing close.
I would caution about putting a bigger carb on your engine...think it will be a waste of money.

 

[1967coronet440]

Years ago....1979? ...my brother's '69 GTX nylon timing gear failed. We had no money, trying to get through Texas Tech paying our own way...He paid a local rebuilder to rebuild the engine...think the builder bored it out .030. something like that. After everything was done, the engine would start and run, everything seemed fine, but nowhere near the power of the stock engine. On the dyno it showed 125 HP at the rear tires?! ...Before, it would set the tires on fire. After the rebuild, barely spin at all. And I have seen that many times when a rebuilt engine with bigger cam, cubes what ever and it just doesn't produce. Very disappointing. Also two engines built to same specs, one produces great power the other one nothing close.
I would caution about putting a bigger carb on your engine...think it will be a waste of money.

Mismatched parts can lead to very disappointing performance

 

[Wookie316]

Actually, I'm trying to get here:

http://www.forbbodiesonly.com/moparforum/threads/dyno-day-511-lives-again.134412/

I know I'll need a vacuum pump and probably a few more cubes but that is my goal for this build. AndyF has already got 775 without the porting so I think it might be doable with the extra cubes and airflow I have over his build.

I know that guy. He’s a crazy Canadian! Wait.... that’s me!
Glad my build is helping and inspiring others on the board. Remember my motor is 13.5-1. Not at all a pump gas friendly motor. That said the same combo with less compression should be very close to 800.

 

[1967coronet440]

Who the hell is AndyF

 

[Wookie316]

Who the hell is AndyF

Moparts

 

[Tex013]

AR engineering

Tex