I have a 383 Lt1. Just had it dyno tuned and put down 420 RWHP@7800RPM. When i run the numbers in any desktop software dyno program for my cam specs and head flows i get 540FWHP.
Air fuel ratio looks great from beginning to end.
I have a MSD digital 6 that is going to get installed shortly, but i was just wondering what limitations there could be. Exhaust is true dual 3in. all the way back through long tube headers. 58mm throttle body, granetelli maf, and moroso cold air intake.

What could be holding me back.
Motor is a solid lifter setup also.

 

7800? what engine management are you running? LT1 intake?

 

wow 7800 rpm, you got a rotary in there?

 

7800 rpm... that's not a typo?

What mufflers? What trans? What gears? What dyno? What ECU?

 

7800 To add to the questions, what valve springs? what cam? what rear end? What heads? Electric WP? Underdrive pulley?
From a realiablity stand point, what pistons, rods, crank, bearings, oil pump?
And DesktopDyno programs are based on perfect conditions, it would be nearly impossible to emulate their numbers exactly.
EDIT: If your really turning 7800, I want a sounds clip.

 

If you know enough about LT1s to build an engine that'll rev to 7800rpm, then you sure as hell won't be in this forum asking whats wrong with it or putting a bunch of faith in desktop dyno. However if it is just a typo, then you'll need to give more deatils about your setup. The fact that you have a Granatelli MAF, 58mm TB, Moroso CAI and are planning on installing an MSD 6 means you have an optispark, hence stock PCM. So I'm guessing you meant to say 420rwhp @ 6800rpm. If thats the case, that may not be too bad. If its 420rwhp @ 5800rpm, then that's awesome. In any case, give more details about your specs and why you were expecting more power.

 

Yes everyone i meant to say 6800RPM Type-OOO Also i am running electric water pump no AC. I have custom ground cam from Bauer Racing. Specs at home. Valve train is all comp cams roller.

 

So how are we supposed to answer this question without knowing anything about your combo or you posting up the dyno sheet?

 

Your asking a question that relates flywheel HP to rear wheel HP, but you have told us nothing about the drivetrain. Losses can range anywhere from 12% for an M6 to 25% for a TH400 with a loose convertor.

Why not add a "signature" with basic info about the car..... much better chance of getting a meaningful answer.

 

dont feel bad, my car put down 280hp baseline and 303hp tuned 371 rwtq tuned, thats through a moser 12bolt 33spline axles detroit truetrac diff, 4l60e w/ 3600 stall converter, but ya know what? i went 11's before the tune and full weighted car as well. on chrome wheels and drag radials last year

 

which is exactly why folks should not be so quick to throw their engines into the bay after a 'low' dyno session.

 

if ur looking for a dyno queen, buy a 03-04 cobra get a cold air exhaust, pully and tune and u will easily have 450 rwhp, like a buddy of mine, at the track he was running 12.3 or 12.2s if hes lucky with that hp on that car

 

I dynoed 330 and 315 yet the car went 119 in the 1/4.

Dyno's are o.k. to tune but thats it.

Also know someone that only dynoed in the hi 400's but his car ran 9.30's

 

What where your TQ numbers? Just curious.

Dan

 

I think you just failed to understand just how massive the losses are from not just the drivetrain but intake and exhaust restrictions as well as accessories.

One reputable LT1 crate motor builders 440hp motors are solidly 320rwhp with A4s behind them.

I also think you are putting a bit too much faith in a SIMULATION too, but that said at least for an auto 540 at the crank is going to be around 420 at the wheels. If you have a manual tranny I would chalk it up to the simulation being a simulation rather than a real test.