Disappointing day on the dyno

[Brewzer67]

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.

 

[dieseldazzle]

Did you have a radial tire on it during the dyno session?

 

[68 HEMI GTS]

Pretty hard to see your chart. Chassis dyno's are affected by a lot of things. They are better suited for tuning than pulling big numbers. Take it to the track and see what kind of et/mph it pulls. That'll tell a better story. I will say an out of the box carb probably isn't optimal. If money is tight, throw a bigger main body at your carb.

I remember when I worked at livernois we had an 03 cobra (it was one of the shop's many test cars). It made around 650 to the tires. At the track it would run 12.0's-11.90's. (Just to give you an idea that the numbers aren't the end all). I had a car that made a 100hp less at the flywheel than that cobra did at the wheels and it was just as fast.

 

[Cranky]

I agree with 68...the best dyno is the track itself. All others are just a tuning tool.

 

[dvw]

My Buddy's Duster dynoed 370 at the wheels, been 10.80. Take it to the track with some good tires. Run it, weigh it.
Doug

 

[Brewzer67]

Did you have a radial tire on it during the dyno session?

I did.

 

[Brewzer67]

Pretty hard to see your chart. Chassis dyno's are affected by a lot of things. They are better suited for tuning than pulling big numbers. Take it to the track and see what kind of et/mph it pulls. That'll tell a better story. I will say an out of the box carb probably isn't optimal. If money is tight, throw a bigger main body at your carb.

I remember when I worked at livernois we had an 03 cobra (it was one of the shop's many test cars). It made around 650 to the tires. At the track it would run 12.0's-11.90's.

It will get a bigger carb over winter. I ran out of money this year. I still have to order the dana so the rear end won't blow up on me next year. That is the last big purchase until spring. Here is a better pic. But all it made was 418 hp@5600 and dropped from there. Torque was even worse. 489 ft. Lbs. @ 4100 and dropped from there.

 

[Brewzer67]

My Buddy's Duster dynoed 370 at the wheels, been 10.80. Take it to the track with some good tires. Run it, weigh it.
Doug

That will be next year after the rear end is in. I don't trust the 8-3/4 that's behind it now. Factory axles and a lot of miles...

 

[68 HEMI GTS]

Mustang dyno's can even put up worse numbers than a dyno jet. It does look like the peak is early. I think you're gonna need 1050 dominator to even get an idea of what it's capable of. I wouldn't be concerened yet.

 

[RT K_line]

Don't beat yourself up, it's still a cool mopar. Like everyone else said take it to the track then post your results. I'm sure you won't be disappointed.

 

[Dibbons]

Can you run the motor build specs through one of the computerized dyno programs? Would be interesting to see where the power peaks are in a program dyno compared to what you have in hand.

 

[Tex013]

The operator may be correct in regards the converter .
I have a 5000 stall , 9 1/2"
With my 440 it showed 430rwhp with flat power from the stall rpm. Put my 505 in and dyno shows plus 5 rwhp at same stall plus 100rpm . But runs on average 4/10s and 3 1/2mph faster in the quater .
Oh i have a 850 based holley hp1000 , under carbed .

Tex
.

 

[Brewzer67]

Can you run the motor build specs through one of the computerized dyno programs? Would be interesting to see where the power peaks are in a program dyno compared to what you have in hand.

I think I will just for giggles. I pretty much already know what it should run at a minimum as it is very close to AndyF's 470" TF 270 build. With the additional cubes and head flow I pretty much expect to run near the same numbers he is with his dry sump motor. I figure what he gains with the oiling system mods I should make up for with my cubes and flow. I use a stout 7/16" pushrod and also had the geometry on the rockers corrected by Mike at B3Racing and it shows up with minimal lift loss. My .715 lift cam actually specs out at .699 measured at the retainer.

Can anyone recommend one that has proven to be fairly accurate?

 

[dieseldazzle]

Just the track homie....put it in the car and drive it.

 

[Brewzer67]

Just the track homie....put it in the car and drive it.

It's in the car and I do drive it. I just can't get it to the track this year as I have too much to do yet. The rear end will grenade for sure when the car hooks behind this motor so that is a must to be replaced before taking it to the track. I also have to finish installing the cutoff switch for the battery, I need to buy slicks, a racing jacket, a new helmet, and a driveshaft loop (since I will be down in the 10's for sure with this combo). This is a big jump from where the car was before. I have more needs than I have time and money for right now unfortunately.

 

[Sweet5ltr]

526ci 10.8:1cr
TF 270's - ported
Indy 4150 - ported
.700 solid-roller cam
850 mighty demon carb..

418rwhp @ 5600rpm? Something is seriously wrong here. That engine combination should be upwards of 675-700 fwhp. Dynograph looks as if the engine is starving for air. Throttle plates in carb opening 100%?

 

[Brewzer67]

526ci 10.8:1cr
TF 270's - ported
Indy 4150 - ported
.700 solid-roller cam
850 mighty demon carb..

418rwhp @ 5600rpm? Something is seriously wrong here. That engine combination should be upwards of 675-700 fwhp. Dynograph looks as if the engine is starving for air. Throttle plates in carb opening 100%?

I confirmed that they are 100% open when the gas pedal is to the floor but I cannot confirm the operator had it floored for the test. I would think so since the results were all very close and two of the three pulls were almost identical.

 

[Mike67]

It will get a bigger carb over winter. I ran out of money this year. I still have to order the dana so the rear end won't blow up on me next year. That is the last big purchase until spring. Here is a better pic. But all it made was 418 hp@5600 and dropped from there. Torque was even worse. 489 ft. Lbs. @ 4100 and dropped from there.

View attachment 523950

Guy on FB in one of the mopar forums has a new 1050 for $600...

 

[Brewzer67]

Guy on FB in one of the mopar forums has a new 1050 for $600...

Yeah, saw that but the cash just isn't there. With the switch to Trick Flows and the roller cam and manifold and porting and electric fans and steering column and Dana...
You get the idea. Next year...

 

[Sweet5ltr]

I confirmed that they are 100% open when the gas pedal is to the floor but I cannot confirm the operator had it floored for the test. I would think so since the results were all very close and two of the three pulls were almost identical.

It almost seems like you're down a cylinder. Car should easily make 500rwhp on its worst day, even on a mustang dyno. Graph seems accurate, spread is correct between peaks. I'm just surprised the torque peak is so low (which is why the results are disappointing), even with 526ci, should be at least 750-1000 rpm higher (I would imagine). 380 cfm of airflow @ .700 lift, something is SERIOUSLY wrong here for it to have a torque peak @ 4100 rpm with max-wedge port heads. Converter seems way off for this combination.