BLUF: My 383 L98 Dyno tuned results was 234hp @ 5600 rpm 247tq @3800rpm to the rear wheel WTF!!!! I love my Car, but with all the mods I've put into this car I've was expecting at least 375 -400 RWHP. I think I got screwed at the dyno shop. Below is a list of mods prior to each dyno. Each dyno was done a different locations.

Mods berfore 1st Dyno (On Dynojet)
*89 2 bolt main roller block
*stroker 383 Scat forged rotating assembly (balanced, blue printed)
* Comp Cam X4 270HR (lift 507int /474exh) degree in.
* 1.6 int/ 1.5exh RR
* Dart Pro 1 180cc Alum Heads
* Stock TPI Intake System
* 58mm TB
* 24lb Injectors
* MSD 6AL
* Stock Exhaust Manifold
* Stock Cat Convertor ( 1985 No pre cats, one main cat)
* Flow Master Mufflers
* Stock Tranny
* 2:73 Rear Gears
* PCMfor less Mail Order tune (870ecu)
Dyno'd results 2 July 07: 278rwhp@4600rpm 361rwtq @3600rpm. Dyno's at Performance garage. I knew having the stock intake and exhaust manifolds would restrict the engine and not allow it to make max power. I wanted to see where I stood for horse power.

Mods Added before 2nd Dyno (on Dynojet)

* TPIS Mini Ram Intake
* Comp Cam XR 288HR (520int /540exh gross lift) degreed
* 30lb Injectors
* TPIS LT Headers, 3in. Y pipe ,Gutted Cat Convertor
* 3000 Stall Convertor
* 3:73 Rear Gears
* Accel Gen7 Thruster ecu (speed density setup)
* Dual Sync Dizzy (sequential fire)
Dyno Results 1 March 2012: 234rwhp @5600rpm 247 rwtq @ 3800rpm. Tuning was done by Virginia speed.

Can Someone help explain to me how could this be?
This is a HUGE DISAPPOINTMENT!!

 

Something isn't right. What kind of dyno was used?

Is the car driving ok?

 

Dynos an be very humiliating, but, to would have thought at least 330, depending upon the kind of dyno. Were the results averaged to sea level, was it a dynojet or a mustang. Main question is that with a miniram why are you only turning 5600 rpms With the cam you are using you should be around 6500 rpm.

 

Something is not correct, really poor tune or poor set-up of the car. Something wrong with the dyno set-up causing it to read low.

 

do a compression check..make sure 100% the bottom end is good.

I doubt your problem is there.

Clogged cats are well known to be issues in l98's so check that.

Next, look at fuel / plugs. Is every cylinder firing?

Next, look at the computer end of it. What were your Air/Fuel ratios? 13.2:1 typically makes max power naturally aspirated.

Ok. next.. Knock sensors.. was there something clanging or rattling causing false knock?>

Something is not right.

 

Can you post the Dyno printout..maybe that can shed some light

 

There is the first mistake. If you want, I can give you the name and number of a tuner who will make it right.

I wouldn't trust VA Speed for anything that involves them touching my car. I wouldn't wish that on anyone.

They don't have a guy there who knows how to tune btw. I made that mistake personally. Fortunately, it was caught and fixed before any harm was done.

 

Buy a wideband and make sure the afr is correct. My car has never been on a dyno (bunch of dragstrip runs), and I do my own tuning based on my wideband readouts. Do a leakdown to make sure your motor is ok, then check the tuning.

 

Tune is way off<<<< or major issue
my L98 TA 358 HSR 11:5 patriot heads 58mm TB, edel shorty's made way more power then your 383... what did you set your static timing to???
as above check with a wide band... get someone reputable or learn and burn

 

Thanks guys for your responses!
* BLK89Z51 PM me the number of tuner.
* I'll check the plugs and plug wires this weekend. I think there maybe some burnt plug wires causing the dead miss.
* The FPR is reading 45-50psi at idle.
* My exhaust has no Cats so there nothing to get clogged.
Today as I drove it home from Va Beach to Newport news it ran with a dead miss under load, but at an idle it ran fine. They (Va Speed) mentioned there was dead miss under load as they tuned it, but needed more time to find the cause which would have driven up the my final bill. Ahhhh NO THANKS!
At the time when I did the 1st dyno I knew I needed to mod my intake and exhaust systems in order for the engine to breath and make HP. After the intake and exhaust mods were made. I didn't get it dyno during that time, but I know my HP and TQ had increase significantly from my time slip at the 1/8 mile track. I before the installation of my current cam and ecu.
My car went from an 1.90 60' 8.80 1/8 mile @ 78mph to running 1.61 60' and 7.75 1/8mile @92mph with a mail order tune for a 870 ecu.

 

if the TPIS has the same characteristics as the holley stealth ram <> does not come alive till 10 -12 deg.. up to 16 is outstanding

 

Shoot, if you still have the PCMforless chip, try that instead of the VA Speed tune.

You need to data log after that and post up so the brains can look at your logs.
Something is not right at all.

 

I replaced the factory ECU with a Accel Gen7 DFI Thruster. This system is a tune on the fly with a laptop. It's a speed density with sequential firing order setup.

 

PM Sent back.

Put in some fresh plugs and check the wires/cap/rotor. I've been running NGK TR55's.

 

You should be able to do your own tuning with a Gen 7. I have a buddy at the strip doing that. I have an ancient Gen 6 with no learning capabilities, no closed loop at wot and I can tune even though I have half a brain. Like I said, all you need to do is read your wideband that you already have with a Ge 7. No one will be able to tune your car as well as you because no one will put in the time required. Good luck.

 

ahhhh what can i say about Dynos ..... my car for some reason never loved the dyno, my 1st setup 6 years ago made 400 rwhp and run a 10.20 in a full interior car .. Not sure how that happened , what made that day even worst , some kid with a supra pulled up to the dyno and made 700+ rwhp and spent the rest of the day telling me what i should and should not do with my setup ... anyways i ran into the kid again at the track and his 700+ HP car was only doing 12 sec passes ... Not sure how that happend either .. LOL

 

I can tell you what happend on that one, torque happend

To the OP: How does the car feel compared to before the new mods and new tune? I am sure 100 ft/lbs would be very noticeable to drive. Try retracing your steps backwards, till you get it feeling the way you want it then put it back on the dyno.

 

maybe ..

If remember correct , High stall trans convertrs can mess-up dyno numbers ..

 

Thanks to all for your response! This weekend I'll start by checking the plugs , plug wires and fuel pressure. then I'll go from there.

 

To some degree but not THAT much. Dynojets are actually amazingly consistent from dyno to dyno in my experience. You swapped the cam, did you double and triple check the cam to crank timing relationship before you put it together?

I only ask because once upon a time a friend gave me a gear drive setup to try. SOME HOW, SOME WAY I managed to install it a tooth out of time. Because of my LT1 I installed the opti the only way I could and the car ran, OK but not great. It had a few really stupid driveability quirks that just about drove me mad. I never got to a dyno with it but I took it to the track and all the sudden my car which had run in the 12's was running mid 14's? The very next day the engine came apart and I found my problem. I wouldn't have thought it possible, but there it was staring me in the face plain as day.

I noticed that the gear drive was also slightly wearing on the timing cover so I decided to ditch it in favor of a double roller setup.

Of course try everything else first. Gotta get that misfire fixed.