Disappointed Dyno

[grumpyvette]

Disappointed Dyno
BLUF: My 383 L98 Dyno tuned results was 234hp @ 5600 rpm 247tq @3800rpm to the rear wheel:cuss 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!!

can you post a clear picture of the dyno results sheet?
your hardly the first guy to voice similar concerns and in most cases its the result of a tuning problem , a part or parts installed incorrectly, a parts mis-match,or a restriction in the exhaust flow or fuel pressure or ignition advance curve, or badly adjusted valves, have you done a compression test? that intake can support 500 plus horsepower but those heads are a bit restrictive on a 383 displacement, but thats obviously not a major contributing factor at these lower rpms, and both the heads and cam should allow significantly more power, can you post CLEAR pictures of your spark plugs? Ive seen very similar results that were carefully inspected that were the results of several factors, a clear sheet showing your manifold vacuum ,ignition advance curve, exhaust back pressure ,fuel air ratio, fuel pressure etc would sure help here, IM reasonably sure clues to the cause will be available if theres enough data to look thru, ARE YOU PULLING ANY TROUBLE CODES? have you done a compression and leak down test?Ive frequently seen things like a restrictive catalytic converter, cause problems like this, and a faulty ignition that was not advancing correctly as the rpms increased, or badly adjusted valves or low fuel pressure can easily result in an embarrassingly low dyno numbers that was reasonably easy to correct, and increase rather dramatically, once the cause of the problem was located and corrected. I wish you were located locally things like this can be fun to diagnose, and rewarding once located, verified and corrected.
catalytic converters can be tested on car, with the engine running, at operating temperature.
its a good idea to test with a vacuum gauge as described earlier, but a quick check can be done with an I.R.TEMP GUN,
Using an infrared temperature tester, like I link to below, the "gun" style with the red laser pointer, measure the inlet and outlet temps of the converter.

The temperature difference from one end to the other, should be approximately 100 deg/F.

The INLET should be 100 deg/F or so COLDER than the OUTLET end.

If the outlet is significantly colder than the inlet, converter is usually plugged.

heres the one I use and recommend

http://www.professionalequipment.com/ex ... ermometer/



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[grumpyvette]

well your fuel air ratios a bit rich but still not excessive to the point its likely to be the lone source of your problem,according to this posted picture , but I don,t see much useful info other than that but its rather obvious power starts dropping off far earlier in the rpm range than would be ideal, that can indicate a restrictive exhaust or ignition advance curve issues among other things, do you have any ignition advance curve info, any intake vacuum readings and exhaust back pressure info? any trouble codes? what were your installed valve spring pressures and clearances set at?
what is the ignition advance curve, rpm/degrees and total advance?
it should look a bit similar to this??
what are your plugs gapped at and whats the coil voltage?

many dyno print outs have useful info like this one

Ive helped lots of guys with similar issues, in the past, its usually simply a step by step check and verify process,
you would be amazed at the silly stuff that gets ignored or over looked that can cause significant power losses, you can,t assume anythings correct you need to swallow your pride and start verifying, youll find the cause

 

[grumpyvette]

the pictures need to be clearer to be sure but it sure looks like your not getting nearly enough cylinder burn (usually the result of not enough advance in the timing or an overly rich fuel/air ratio), your dyno showed the f/a ratio to be rich but not quite enough to get that result suggest advancing the timing 2 degrees with new plugs and better ignition wires and MAPPING YOUR EXACT IGNITION ADVANCE CURVE


these links should help

http://garage.grumpysperformance.co...ers-and-yeah-thinking-it-through-helps.15137/

http://forum.grumpysperformance.com/viewtopic.php?f=70&t=202

http://forum.grumpysperformance.com/viewtopic.php?f=70&t=4683

http://forum.grumpysperformance.com/viewtopic.php?f=70&t=5428

http://forum.grumpysperformance.com/viewtopic.php?f=70&t=840

 

[mathd]

The first spark plug looks like there is oil on it??... not a good thing there. i think thats why there black not because of the A/F ratio
But the plug base(where you plug that 5/8 socket) is turned blue (overheated steel?)wich mean those spark plug got really hot? maby too late ignition advance..

Id check the ignition first(plug gap, wire resistance little things first), looks like some plugs wasnt firing, wet like that.
First one looks like the cylinder chamber temperature was real low vs the 2nd one.
I wish the 2nd one was clearer we could see if the tip is molten? its hard to tell focus was on the background lol

It could be nice to seee all of the plugs too and to know wich one go to wich cylinder.

 

[grumpyvette]

many auto lite plugs come from the factory with the blued steel finish, so thats not related to the problem, but I totally agree that clear pictures of all 8 plugs, labeled as to the cylinder they came from, would be much more helpful