I returned on Saturday from a dyno-tune on my modified 90 L98. I know the dyno is not the end all determining factor when it comes to performance and the track is what it is all about. But when things fall way short of expectation after so much work and expense, you just have to rant. This is the second time I have had the this car on the dyno after the completion of a round of mods and this is the second time I have been disappointed. With the first round of mods I had a mail order tune and this last round the car was being tuned while on the dyno.

It produced 326RWHP and 348RWT on a Dynojet. The bottom end is stock. Nothing above the block is stock with the addition of a S/C that was putting out 6-7 lbs of boost with water/alcohol injection. The car is still emissions legal and is an auto with 3.07 gears with 52,000 miles.

I was hoping for around 375RWHP and 400RWT. The tuner did tell me a few things to do and then come back for more tweeking. He did not say and I did not ask him what he was thinking the set-up should make. I guess I should be happy that the engine survived and will return to fight another day.

Thanks for the opportunity to let out some frustration.

90Indy

 

My modded 383 made 309 hp and 389 ft lbs of torque. It ran a best of 12.02@113.
I don't think your numbers are bad at all.

 

You didn't mention anything that would put it into perspective. What was the ambient air temp? Humidity? What did your air/flow ratios look like? Was the curve smooth or peaky? There may be more on tap there.

 

I am assuming there is more on tap since the tuner wanted me to revise my vacuum connections and do a few other things and then run it again. As far as the conditions they were:

Temp: 91 deg F
Humidity: 30%
The air/fuel was pretty much a straight line running at 11.75 for the full pull starting at 3900 and ending at 5500 rpm.

The one good thing about the graph is the smooth line for both the hp and the torque. There are no big dips and it has a steady climb until the end of the pull. The tuner said the fuel pressure was not high enough due to the vacuum line plumbing to the FMU. I will complete his recommendations and try again.

90Indy

 

Cool, it sounds like there is definitely more to be had. A 90+ degree day certainly isn't going to be very helpful to you sitting there staticly on the rollers. Is there an intercooler of any type?

 

Does emissions legal mean stock L98 exhaust with 3 cats and all or something else?

I could imagine a 390 hp callaway making similar numbers at the wheels.

 

No intercooler. I installed a Blowerworks water/alky injection system. Must have worked well as the tuner did not mention an excessive knock count and the stock pistons don't seem to have any holes in them.

90Indy

 

No, it would fail a visual as it has headers and I have deleted the two precats. It does however pass the sniffer test here in Texas.

90Indy

 

Interesting, check you mailbox.

 

I just checked both e-mails and the pm box. Nuffin in dare.

 

Look now and you will find..


Considering the numbers Pete can knock down with less power sounds like you have plenty. Don't let the dyno bum you out, most guys make **** up anyways. I raced a buddy with a 93 Musatng who before the race told me it went 12.50's on street tires and put down 390rwhp.
Not even close !! He ran a 13.89

 

In my case, shift points were 5200. Torque is what drove me down the track. A 1.590 60' time on that run helped as well.

 

What's your entire combo? Is the graph SAE corrected? Are you still using the stock style TPI?

 

The heart breaker.... I have seen some really high dyno number cars do not so good at the track. That is where I would test it.

 

Its all about the combination to get down the track quickly. I have 425/428 rwhp/tq and I was only able to get a 11.61. My 60' times werent all that great. But i tell you our cars alignment in the rear and tires make a difference.
Your power is irrelevant. The dyno is a tool to use to verify and check things out. The timeslips at the track that day and hour-minute-second etc are what counts. If it drives good, feels good and doesnt have any issues, then I would be pretty darn happy.
just my 2 cents

 

I agree that most quoting dyno #s are FOS....You are over 100hp more than stock, thats pretty damn good. Take that thing to the track and see how it does.

Im razzing a local guy on a Mustang board....348 rwhp but cant run any quicker than a 13.9 (cant drive). Claims a 12.50 on his forum and I know my 13 sec bomb would kill it.

Just use your dyno #s to compare before and afters to your mods/tuning, dont worry about what other guys are saying it should and shouldnt make, most of them do too much reading and dont know squat about what they are saying anyhow.

 

You said this was your second time on a dyno after a round of mods. Was the SC done after the first round? If so, what was the power diff from the first to last time on the dyno. Also you said nothing from the block up is stock. How about being more specific. what kinda heads, intake, cam, etc.

 

There was mustang cobra guy with ton of mods, and he had dyno graph says 490 Rwhp, and ran best 12.20, thats why i never dynoed my car, probably may be 275-325 Rwhp, my car ran best 12.32.

U dynoed ur at wrong time my friend, its too hot, its summer time, dynoed when car coolant temp says 160-180, iam sure u will get different numbers.

 

The list of parts as best I can remember here at work are:

D-113 Heads (ported, revalved 2.02"/1.67", 65.5cc chambers)
SR Plenum/Runners/Intake (ported by me)
30# FoMoCo Injectors
Comp Cam (.464" lift intake/exhaust before added RR lift)
1.6 Roller Rockers
Hedman Elite Headers (1 5/8" dia)
Crane Fireball Ignition
Walbro SS340 In Tank Fuel Pump
Bosch External Fuel Pump
2400 Stall Torque Converter/3.07 Rear Gears/D-36
Random Technology High Flow Main Cat/No Precats
Flowmaster II's
DeWitts Radiator

I can't think of any more big items.

90Indy

 

Did it have the SC on it when you dynoed it last time? What was the power difference?