Hi guys

I was excited last week took the car to the dyno to see what result happened from my changes to the car.

Ok here is car last year
4040 with me in it
440 40 over 9.5:1 compression ratio
440stealth heads
comp cam XE 268 degreed to 107 LSA
770 street avenger carb
street dominator intake
shorty style headers
727 2600 stall converter
3:23 gears
uncapped headers thru 2.5 inch cutouts

HP 327
Torque 404

Ok tonight

4040 with me in it
440 40 over 9.5:1 compression ratio
440stealth heads
comp cam XE 274 put in straight up at 110 LSa
750 Holley Double pumper 76/78
street dominator intake
shorty style headers
727 4200 stall converter
3:91 gears
uncapped headers thru 2.5 inch cutouts

HP 311
Torque 334!

ok, I'm down 16 HP and 70 lb of torque!

It doesn't make sense!

The car runs beautifully, pulls strong now all the way up to 5800 rpms! It is a blast to drive. It comes out of the hole like its on fire now.

Why would I be down?

Thanks for any info

Ok for the record temp and humidity for pretty similar!

Take it away fella's

Mike

did u get any afr's?

What changes did you make while still on the dyno
to get it to pick up

Afr's were good most of pull around 12.5 and at about 5600 started to richen up a bit.

Things I did, were jet it up, up front to 76 and backed off a bit in back 78 jets, which was a 2 jet sized up and one down in back

Timing was 36 all in At 3000 rpms

Mike

Loose torque converters on chassis dyno's often lead to results that don't match actual performance. A manual trans would help make the playing field more level. I assume this is the same dyno used in the previous testing? What info was the dyno operator able to give about the results?

Did you verify that the new carb is all the way open when the gas pedal is on the floor? Simple stuff first, then look at the tune up One other thing is "Street Avavenger 770" CFM carb versus "Holley 750" CFM D.P. carb Do you still have access to the other carb If so try it next

Firstly... Bigger converters tend to soften number on wheel dynos. Lots of times cars with big converters give off weaker numbers, especially if they have a hard time calibrating the load correctly. Where was peak torque RPM wise both times?

Don't worry about the dynos especially chassis ones they are just a tuning device for the track, run it and see what time it makes then you will know actual HP.

Thanks guys! These are great ideas. To answer the question.

Torque wise it looked like converter came in at 4200 peak!

Cab great idea. I'm pretty sure it was opening all the way, but I'll check it. I do have access to the old 770 street avenger carb.

Thanks for the support. I'll look into these things and get back to you.

Mike

Two things. First I like the evenger carb. It runs real clean and has a great fuel curve. Was your cruise a/f way lean that you had to richen the primaries? If that was good I would not have richen up the primaries. Also was the dyno a dynojet type that is a fixed wieght or was it a eddy curent type? The fix wieght type are more repeatable. Also you would really need to see the acual resaults at the track. The dyno is only a tuning tool. I am surprised that the no. went down with the gear change ussaully they go up with more gear. Put the other carb on and see what happens. Jake

Just went back and read your post and realized that you changed converters. That is a big difference on the dyno. Also it seams to be to much converter for that combo.imo

Opps sorry, it had been a long day! I had a 4200 converter, but we pulled it and had it tightened up to 3800, sorry for the confusion.

So scratch that 3800 stall, not 4200.

Mike

Seems off. Your jetting seems low for a 440. I ran a much milder 440 set up w/ a proformed main body 750DP and ran 76/84's seemed to work well. What is your timing set at? You'd probably do well with it all in full around 2400 and 38*. I take it that is rear wheel HP???

If your happy with its perf. who cares what ANY dyno tells you, just a waiste of $$$ IMO, I never use them & never will, just take it to the track & tune there, thats "real world".

If i had a $1.00 for everytime someone ask me how much HP i was running in my duster i'd have a pocket full of $$$ & would pay for my entry fees each time , I would always tell them "enough to run 10s" LOL, it runs good & i'm very happy with it & thats that .

yes wrong cam degree move it to 105 and it will be all good!

Not every converter has exactly the same torque multiplication.

Testing multiple changes to the engine is fine, but the converter swap did away with any chance of comparing last week's results to the new results.