Big problem with my power dyno numbers
 

Ok, I went to the dyno tuning session today and here is my problem, and here are my numbers. At the wheels I got 350ft pounds and 340hp. I spent 20k on Frank's advice on this supercharger setup and at 9 pounds of boost I gained 0 horsepower over what a stock zz430 would make. This too me is VERY unacceptable. The numbers as far as timing and air to fuel is perfect now, but these numbers are not nearly what they should be. I drove the car today, and it didn’t really feel any faster then my straight zz430 setup. What the hell do you guys think the problem might be? Can you tell I'm pissed?

Is the motor actually seeing any boost?

Yes, 9 pounds in the carb hat.

I'd be talking to the guy that built the motor. You've got something wrong there.

The engine was built by Campbell Auto Restoration. What do you think the problem might be? I was told that since the air inlet on the supercharger is close to the headers and that there is no intercooler, that we should pick up a bunch of HP, but that they said that doesn't explain the large amount of loss.

It could be a number of things.

Just for kicks why don't you try disconnecting the blower and see how it runs? I have a p1sc procharger on a 350. I havent dynoed it yet but Im sure im in the 450-500 range. What was your afr at? Timing?

you don't measure boost in the carb hat; you need to measure it in the intake, somewhere after the carb blades. My guess is you're not running anywhere near that boost level, at which point you'll need to figure out why.

A couple questions. What size air cleaner? Is it mounted directly to the blower or does it have some sort of intake tube? What pulley size? What blower? What timing at WOT? What A/F at WOT?

Don't panic yet, once we get it sorted out you'll be very happy with your choice.

Jody

So it's getting air. Was it getting fuel? Were you monitoring A/F ratio? BSFC's? Post some numbers. Did you purchase a specialized blow thru carb?

Blow thru carb engines are among some of the hardest to tune as they violate the very principle that carburetors are based on: Signal. By signal, the engine sucks or pulls on the carburetor to draw air and fuel during the intake stroke. With a blow thru system, you are pushing instead of pulling. Be patient. Collect and analyze data on available air and fuel across the pull. Contact ProCharger and your custom carb builder to analyze the data. If you don't have a custom carb builder, get one. And get to know him on a first name basis.

Are you on the stock internals? 9 pounds of boost with no intercooler could wreak your day.

I'm sure you will get this figured out. :thumbsup:

Hey Jody. Ill need to pick your brain. The air cleaner is mounted on the supercharger itself, no intake tube. The size of the aircleaner was in the mid range due to clearence issues. It's a P1SC blower, not sure of the timing, but timing changes did nothing for power, and did not hurt power. I thought that was weird myself, but they advanced it 2/3's per pound after going down 1 degree per pound, or something like that. I'm not sure of the A/F. We took the carb hat off and it blows well into the engine, this is all I know.

All the numbers I left in the car. I know that as WOT we read 11.8 to 12.5 on the A/R meter though the rev range to 6k. On the freeway at cruise we had 14 to 14.5. We also had an issue after a long downhill sweep, I was on it pretty good in 2nd at a high RPM and when the straight away came, the car died. They checked the floats and it's a bit on the low side, but they figured it was not the carb that lead to the stall out. The carb is a holley, but was sent to the carb shop and rebuilt for blower power. The boost reference is below the carb height.

The engine was rebuilt for blower power. Everything is forged.

You want to mount your boost refrence line for the fuel reg in the carb hat. If you mount it below the throttle blades it will see vaccum and lower your fuel pressure. This is how the guys set them up at turbomustangs.com. Do you have a msd btm? You want to retard timing with boost 1 deg to 1 psi. Or you can lock it out.

They had the boost reference on the carb hat, and it was running too rich at WOT. When they moved it, that's when they saw better A/F readings. The timing is what you are referring too, spot on.

Just got off the phone with Jody, thanks again BTW, I should really pay you for your advice. We chatted about this problem, and got to the filter, which is mounted on the supercharger. We had to use a smaller one because the one that came with the kit, was hitting the master cylinder. So we got one half the size. Jody thinks this could possibly be a problem. I'm thinking Jody is on to something here. They are going to re dyno it in the morning without the filter on for a few runs. Just to ask, has anyone had similar problems with this before?

What size pulley do you have? What size cam are you running? Whats your compression?

You have a PM
 

Mike,

Chrs here. Sorry you are having trouble dialing in yor car. Hang in there man, it will get sorted out. And, you have a PM.

Take care,
Chris

1 1/8 pully, cam specs are the same as the zz430 cam. Not sure what they are, and the compression is 8.9-1.

My imediate thought was air cleaner. Also, do not under estimate drivetrain loss. I have seen many cars loose 25% on a RW dyno. So you may already be at 500HP before final tuning, which would not be that bad after all.

I should only have around 10 to 15 percent drivetrain loss. TKO 600 with 373 gears in a 12 bolt with a true trac. We had to downsize the filter by about half from stock.

You might try getting cooler air from outside the engine bay, and it may allow a bigger air filter (I used a 12" long, 8 inch round conical) :

http://i98.photobucket.com/albums/l2...6/DSC_0051.jpg

I'm also thinking air filter.

Another thing you didn't mention, although I'm sure Jody talked with you about it... what carb hat are you running?

A poor carb hat can absolutely KILL the power, it almost feels like someone cuts the fuel off when you get into the boost.

How closely was the boost watched? Any signs of belt slippage?

What kind of timing numbers are they running (initial, total, when is it all in, vacuum advance or not, and retard amount?)

As far as the discussion on vacuum lines & routing...

The fuel pressure regulator reference goes to the carb hat. You want the pressure in the float bowls to increase at a rate equal to the pressure at the top of the carb & vent tubes, since that's the pressure seen inside the float bowls.

Your timing retard box and everything else should be connected to manifold vacuum (as normal), i.e. below the carb.

http://i119.photobucket.com/albums/o...h/IMG_0262.jpg
Ok here is the carb hat. This picture was taken a few months ago, so a lot has changed. I'm not sure of the timing numbers. I was told by a few people that the boost reference should also be on the carb hat, but there was too much fuel going in at WOT. They moved it below the carb and that made everything better. They also blocked off a power valve in the carb as well. I hope this answers some of your question, heheh

Procharger sent us a 1 inch carb hat spacer, because even they said that the quick curve of the carb hat was too much, but CAR had to shave it down to 1/2 inch because of hood clearences.

Pics sent
 

Mike,

Chris here. I just sent you 2 emails with pictures of my air filter setup.

Hope this helps.

Chris

That hat isn't helping you, unfortunately. It's not the worst hat out there but it's far from the best hats (i.e. CSU, EV, and SDCE.)

In fact, if you were to dyno with that carb hat and 8 EGT's or WBO2's I'd bet you would be very surprised at how much the mixture varied cylinder to cylinder and would probably end up stagger jetting the carb.

A good carb hat makes tuning much easier and will also make more power.

If it was running too rich with the FPR reference off the carb hat, the correct fix is to adjust the fuel pressure and/or tune the carb-- not to move the FPR reference.

Also, what intake are you running? Looks like an RPM Air Gap. A dual plane will work with a blowthrough setup (I ran mine with one for a while) but a good single plane will have better airflow distribution, a Victor Junior is usually the hot ticket for a blowthrough SBC.

Was that $20k a typo? :_paranoid

I think your stock cam isn't helping you out either. You want a cam with 112-114 lobe seperation. You might want to see what that cam is.

Is there a better carb hat? Yes I have the air gap. Ill get with CAR about the boost reference location. Only problem is that if it's moved, then we will have to redyno the car. No big deal as it will need to be done anyways. Is the Victor Jr taller? Also, thank you for the advice as well. You guys never cease to amaze me of the knowledge in here.

Nope. That's what everything has cost on this end so far.

It's not the ideal cam, but it is the hot cam, so it should be better then a stock cam.

you did all that work and did not match the cam?

the boost reference for the fp regulator must be in the hat. That could be the dying issue you saw. The reason for this is becuase the carb is seeing extra pressure even when you're not in boost. If you do not compensate the fuel pressure regulator then the hat may see 4-5 psi even when the motor is not seeing boost, and the 6 psi of base fuel pressure you have will now be only 1-2 psi, due to the pressure in the bowls reducing the fuel pressure the carb sees.

You must move that back to the hat, it needs to rise evenly with what the top of the carb sees or you're going to be chasing dying and tuning issues forever. The boost gauge goes under the throttle blades, but not the fuel pressure reference. If it's still too rich you need to tune the carb.

Jody

Hey Jody, got your IM. I think they did pulls with the boost reference on the carb, that's when they had problems. I don't pretend to know about this stuff though. I know there were running really rich with the boost ref on the carb. I just sent Mark, the tuner the info from this thread and what you guys have been saying. I think they had the boost reference on the back of the hat, not on top. Does it need to be on top of the hat?

Actually the cam specs were not to bad. We are not looking to rotate the earth here, just make some good power.

As for HP loss.

10% to 15% is not always true. I have seen documented losses of way more then 15% right before my eyes, with engine dynoed, then wheel dynoed, then raced projects.

A few case and facts.

Case one. Michael's Prodigy. On a Friday afternoon at 96 degrees on the engine dyno it made 684HP, 2 days later, Sunday afternoon at 95 degrees it made 455HP at the wheels. This is a TKO, 3.73 car. Also, for performance reference. The following Saturday in Pigeon Forge we were running 97MPH trap speeds in the 1/8. Prodigy has since run 101MPH 1/8 mile traps spinning the tires. For reference, My street racer was running 99MPH in Pigeon Forge and runs 100MPH at the 1/8 mile on motor at home.

Case 2, My Just Bring It street racer. Made 645HP on motor on the engine dyno (a different engine dyno), made 414HP to the tires (same dyno as Prodigy). It is a automatic TH350. For reference, My street racer runs 10.70s, 126MPH in the quarter, 100MPH in the 1/8. Also, it made 635HP to the tires on nitrous, and run 9.30s @ 146MPH

Case 3, Parson Chevy 2, Made 635HP on the yet another different engine dyno, made 440HP on the same wheel dyno as Prodigy and my Just Bring It street racer. It is also a TKO, 3.73 car. Parsons car has not run a quarter yet, but I have some seat time. It will run right beside Prodigy, which is capable of 125MPH + trap speed if they would let us run it out the door. Also, on a roll, say 30MPH, all 3 of these cars would hang very close together as long as they all hooked up.

Is the dyno we are using soft? Maybe, but the street racer went to another wheel dyno and did 428HP, so no big gain dyno to dyno. So long story short, we do not sweat these numbers anymore. But we do not race dynos either.

I don't dont these numbers and issues, but seat of the pants feel is that the car is no faster then it was with the stock zz430. I'm not sure about soft dyno's. What does that mean?

By soft dyno I mean one giving low numbers. As for seat of the pants, no dought it should feel faster. Keep in mind though on motor alone, asuming your nor really getting boost, droping compression will have taken a lot out of it.. So try some of these trick, you will be amazed what a difference some of this stuff will make.

BTW, what RPM is peak HP? I would expect it in the 6200 range, give or take a couple hundred?

You bet, but they're probably taller and may give you hood clearance issues.

Good hats:

CSU
Extreme Velocity
SDCE

I am partial to the SDCE hat (and not just because a friend designed it, he forwarded me a lot of test info and that's why I'm partial to it) and it is probably the lowest-profile option of the three. Honestly all 3 are good choices and far better than any of the ATI hats.

You can see the EV and SDCE hats here: http://www.superiorairflow.com/extreme_velocity.htm

As far as your car dying when coasting down from higher RPM, Jody hit the nail on the head. If you have the FPR reference hooked up below the carb, at high RPM overrun there will still be air stacked up in the hat & float bowls and insufficient fuel pressure to keep the bowls filled since the FPR is referencing off manifold vacuum at that time (lowering fuel pressure) when in fact it needs to increase fuel pressure to offset the pressure that's still in the hat. With the reference line in the hat your fuel pressure will always be at your base pressure setting + whatever pressure is in the hat, keeping the fuel pressure balanced against hat pressure.

340 to the ground
 

340 to the ground is probally about 460 hp.I would check a couple of things one do you have 9 pounds in the manifold at your peak rpm serpentines will slip and if it does the car will feel soft as hell.Two with 9 psi even on a 8.5 to 1 350 with the hot cam you should be making at the very least 580 hp crank and you would definately feel that.I'm not sure if you said your transmission but if it's a auto are you sure it's not sliping,just a thought.Run a compression check on all cylinders see if there within 10 percent of each other and at least 110 pounds cranking.If you have that than i doubt it's in the motor.I've had problems with the procharger units I actually have not used your blower before though but in the past there smaller blowers just did not cut it.I had a 383 with a blower i believe was similar to yours lay down 310 to the ground.We changed pulleys you name it.Not big improvements .Switched to a ysi vortech it picked up 400 hp.and made 710 to the ground and the cam was much smaller than your hot cam.I had good luck with there bigger units like the f2's but even there above 10 psi they really start making heat fast.Ignition Timing can be a huge deal on a 8.5 to 1 motor I've seen 100hp from 25 to 35 degrees the low compression engines like timing at 9 psi and only 6000 rpm But beware carbs timing and boost is a scary deal.If it was mine and i felt good about the tuner i would not shy away from 35degrees total timing at 9si and 6000 rpm this can literally transform the engine.Again beware creap up on it.I would for ****s put some 110 in it and put total at 35 dgrees and see what happens given afr's are in the high 11's low 12's.Hope you fiqure it out