Disappointing Day on the Dyno

Originally Posted by kgordonl

It was actually running lean until the last jet change. We made three jet changes going up two sizes at a time. Maybe I could go back down one size.
I know that the cam is too mild to put up big numbers, but there are guys making 500 to 550 flywheel HP with the exact same cam and heads in 408's. I'm not sure exactly what my numbers equate to in terms of flywheel HP considering the rest of my drivetrain, but I was expecting to go north of 400 at the rear wheels.

+1 to what everyone said.

My 357ci Windsor with AFR 185's and CompCams XFI 236 dur. .580 lift cam
put down 350rwhp.

Yes, something is off on your engine.

I would do a cylinder leak down and compression test to make
sure you have good ring seal too.
Any blow by problems ? dipstick blowing out ?

Just trying to throw some thoughts out there.

and take it out to the track, if she's not running 11's on a 427 with AFR205's
then something is off.

If it is, then who cares what rwhp it has. It's fast regardless

I would love to see the difference with a 4 speed over the AOD!

I agree with the others... something is not right. You should be seeing better reuslts than that.
Was your cam degreed?
If you are able... swap carbs to a Holley DP and see what happens. I say this because a buddy of mine was having troubles like you... and he removed his Demon (and Im not here to demonize demons!) and replaced it with a custom 850DP... and he made huge improvements.

Good luck.

Guys, the answers for a lot of these questions is often very simple... There have been tons of times where somebody comes on here with a potentially badass engine, but it runs like crap. Everybody tells them to get AFR heads, do a port job, new cam, buy expensive parts, etc.... only to find out the throttle isn't opening all the way, it's got a small, crimped up exhaust, the header inlets are way smaller than the ports and weren't opened up, etc. Too many people gather all their wisdom from the internet and build a potentially killer engine, only to brainfart the simple stuff.

Go though the simple stuff first.

No disrespect directed towards anybody. We've just got to get details on all the 'simple' stuff before we can offer any valid advice.

Okay, I'll try to answer some questions:

• The exhaust is 2.5" mandrel bent with an X-pipe, Magnaflows, and goes all the way to the rear. The headers are 1.75" Hooker Super Comps.
• I talked to the engine builder and the cam was installed "dot to dot straight up"
• There was no blow-by, smoke, or any other signs of poor ring seal. It ran very smooth and sounded good.
• I am going to check the wide open throttle this afternoon. That one has me thinking... After we changed the carb, I don't remember anyone ever checking to make sure it was opening all the way!

Realistically, how much power was possibly lost due to the heat and humidity? Are we talking 10, 15, 25 HP or what??? And what is a realistic percentage of drivetrain loss with my AOD? I'm just trying to make a reasonable assessment of just how far down the numbers really were. Then I want to begin the process of working through the culprits starting with the easiest to address. I am going to start by checking the WOT this afternoon!
I appreciate everyone's input and please keep the suggestions coming!

As you know, dot to dot is not the same as degreed. I know that mine was almost 2 degrees out from the visual dot to dot.

That said, if you get a chance to go back on the dyno... have another carb there ... if anything to see the difference.

Mike makes a good suggestion... check for WOT. I know mine was slightly off when I installed my new carpet... in fact I had to lengthen my throttle rod.

Check your plugs for signs on detonation as well after the run.
What springs are you running in your MSD? When is your timing all in?

Well what do ya know... the throttle is about 3/4 of the way when the pedal is on the floor! There is still about an inch of travel left before it is at WOT. I wonder how much power that is worth!

Ah-Hmmm...

OH MY GOD.

No wonder it wont rev past 5500!!!

Let us know what happens!

I completely agree with what n2oMike said in regards to chassis dynos. I would only spend money on a engine dyno if I wanted some useful information. However, that is if the engine isn't in the car yet.

Good catch on the throttle Mike. I can't believe the person doing the tune on the dyno didn't check that! I'd certainly be on the phone wanting to do another session at a big discount. They should not have missed that. Now the information you have isn't very useful.

Originally Posted by kgordonl

Well what do ya know... the throttle is about 3/4 of the way when the pedal is on the floor! There is still about an inch of travel left before it is at WOT. I wonder how much power that is worth!

oops