Powerdyne Dyno numbers and continuing frustration

[1995MGTS]

Not huge numbers compared to the S-trims, NOVI 2000's, and ATI P/D1's but not bad for a little 800cfm blower. Problem is the car will not pull past 57-5800rpm. The car just kind of bucks and stops pulling at that point. I have heard from others that it might be sparkplug blowout. My plugs are gapped stock (.45?) and need to be more along the lines of .32-.35. Anway, here are the numbers:

1st run: 379.1rwhp/377.9rwtq
2nd run: 392.6rwhp/386.9rwtq
3rd run: 394.8rwhp/386.2rwtq

All numbers are SAE corrected and performed on a dynojet.
Max boost observed was 9psi at 5700rpm.
My rwtq was 320@2800rpm and finished off at 360@5700rpm.
Air-to-fuel ratio was very rich and was 11:1@5700rpm.

The hp curve showed no signs of dropping off and if I could fix my problem and pull to at least 6000rpm, I should see at least a peak of 400rwhp, maybe a bit more. Not bad for a 6lb Powerdyne.

[sn95gt19]

im gonna guess and say that its either fuel or spark, i would go with a fmu or aftermarket ignition. it could be your timing too, i would try moving the timing and see what happens

[1995MGTS]

My custom chip supposedly takes care of my timing for me. That is why I don't run an aftermarket ignition. Maybe I should though. The only ignition mods I have are coil and MSD distributor.

My fmu is 6:1 and really keeps the car rich. My air-to-fuel drops below 10:1 from about 4,800-5500rpm.

I already dropped my timing from 15 to 12 btdc.

Hopefully something as easy as gapping the plugs properly will solve the problem.

[Hozer 88GTConv]

I'm taking a stab here, but shouldn't blower plugs be in the colder range and gapped close up(i.e. .030"-ish)? I don't have one yet, so that's just from reading. I'm interested in replies.
Also, what is managing your boost timing retard?
You might benefit from a BTR module.
Again, just a stab. Good luck and those numbers are still pretty good.

[1995MGTS]

I am relying on my Autologic chip/custom tune to handle my boost timing retard.

I think you are right, the plugs should be gapped in the colder range. I have heard from many now that it should be around .32-.35.

Again, I think my numbers aren't to bad with the little PD. If I had something like an S-trim though, I would be talking 450rwhp right now.

Another interesting note was the guy before me had a new PD gear driven XB-1. I think his mods were similare to my car and his best numbers were 386/396 at the wheels. He was seeing 10psi. I would have thought his 1200cfm capable blower would have performed a bit better though. One thing is for sure, his blower will last longer than mine.

[speedytang]

Your out of fuel volumn, you probably have the pressure with the FMU but you just dont have enough of the gas to keep from leaning out which is the on and off brake feeling.

[1995MGTS]

Possible but would I not show a lean condition? My air-to-fuel ratio at 5700rpm was about 11:1.

[LX5liter]

It is probably your plugs as mentioned earlier. One range colder and gapped .030 -.035 should make a difference. Do you have decent valve springs?

[1995MGTS]

I bought my heads brand new in 98 with the GT-40 valve spring kit. Installed them in July of that year and they only have about 8,000 miles on them, 3,500 with the blower. I would imagine they are still in very good condition.

Thanks for all the input guys.

[FASTFRANK]

As you can see I have a similiar setup as you do(read sig) My spark plug gaps are at 35 and my plugs are 2 heat ranges cooler. My car seems to pull hard up to 6200rpm, so I would think that the gap change should be your first step. My car runs very rich for some reason we made 8 dyno pulls in a 4hr span and finally got the air/fuel ratio to actually show up on the graph by removing the fmu. I think I need to have a custom chip made.

[DaveR_GT]

Hey, there are actually others using a Powerdyne!

Everywhere I go all I hear about is Vortechs, it seems no one takes you seriously with a powerdyne.

Interesting thread seeing both your combo's similar to mine. I don't have any problems other than a little rich on the dyno, but I'm not near the power of you guys. hmmm. I know my aod drops it somewhat.

Anyway, just wanted to chime in. I don't have much to offer for your problem. My guess would be fuel starvation even though the a/f ratio doesn't reflect it.

Good luck.

[1995MGTS]

FASTFRANK,

If you can get a good dyno tuner to work your combo, you should be over 400 rwhp and torque. If I can get to 6200rpm, I should be slightly over that mark. My tuner did an excellent job of getting max power safely. With your mods and a 9lb Powerdyne, you should be besting my numbers.

DaveR_GT,

I hear man. Nice car by the way. To be honest, I only bought the Powerdyne because of the good deal I got on it from a Ford Motorsport Dealer. I got it for $1800 + tax brand new. The majority of guys in my car club had Vortechs and a few with Novi's. I was the only one with a Powerdyne so I was the outcast. That's okay, since I was bettering the numbers of several guys with A-trims. However, modded cars with S-trims, no way. I never thought I would have almost 400rwhp from a 6lb Powerdyne after hearing all the horror stories.

My next mod will be the new PD gear driven XB-1. The guy before me on the dyno actually had one and our power/tq curves were almost the same. I don't think his car was tuned though. Just bolted on and was looking at his before tune numbers. His dyno was 386/396 at the wheels. I assume he will not only be well into the 400+rwhp/tq range, but his gear driven blower will last longer than our belt-driven versions.

[DaveR_GT]

When you say tuning... what is there that can be adjusted that the computer doesn't already control?

I know timing can be tweaked, spark plugs, fuel pressure, fmu, tps voltage are about the only things I can think of that can be adjusted. Beyond that does the definition of tuning involve custom chip or programable computer? changing injectors/mass air? Where do you draw the line between tuning and what are considered modifications? And how much real tuning can be done with the stock computer? It's not like the carb days where I could swap jets, make air fuel adjustments and timing curves by swapping a few simple parts or turning a few screws.

When someone mentions tuning on an injected car I often wonder what really can be done?

(please forgive the ignorance, I've had a few mustangs but this is the first time I've really gotten serious about modifying one)

Later

[FASTFRANK]

Tuning the car would mean a custom chip. My car has adj fuel reg. boost retard system and had an fmu. Timing is also adjustable obviously. But even after we adjusted all these things on the dyno runs we could not get the air fuel ratio on the chart until we removed the fmu. We got these numbers on my car with 13 degrees timing and boost retard set at 1 degree per #. My dyno guy seems to think that my pro-m 77 and fuel system are doing their job well and with a custom chip we can get my air/fuel ratio around 12.0 to 1 where it should be. Hopefully with tuning I can make somewhere close to 400 and if not I am very happy with a 353hp car that is dead on reliable and quiet. I am also thinking about dynoing it with no cats just to see what the difference would be......

[1995MGTS]

Just so you guys know, I use a custom Autologic chip. Again, my air-fuel ratio is not really maximized. My air-fuel ratio is on the safe side but below 11:1 with boost. I would have like to get rid of the fmu but my 30# injectors would be maxed and I didn't want that to happen. Whenever I upgrade the supercharger with a more powerful unit, I am going with 42# injectors and getting rid of the fmu.

[FASTFRANK]

What do you run in the 1/4 mile? E.t. mph

[sn95gt19]

i was reading about a kenne bell supercharger, and the guy that owned it had an fmu but the one that he had he could only adjust it so it would cruise and have great low end power, and it would die off on top end. i dont know how different your charger is but i think they are both generally the same. he said that he had to get a vortech fmu and that fixed his prob.

[1995MGTS]

I want you guys to promise not to laugh at my best quarter mile so far. It was before my 7" crank pulley and powerpipe. It was at Carlsbad in San Diego and the only good things I can say about the pass was, it was my 10th pass of the day, hot lapped, my quickest of the day, and I walked the Lightning next to me. I believe it was a 13.48@111.7 with a 2.48 60-ft

I was actually trying to get in the twelves on street tires like MM&FF did with Tony Pedregon's Powerdyne equipped 95 GT. I even had my daughter's car seat in the back. Anyway, easier said than done. I had just dynoed my car at 381rwhp/367rwtq two weeks before that. I really think my car is a 12 sec car but unfortunetly is has a 13 sec driver.