Big problem with my power dyno numbers

[mazspeed]

Originally Posted by MarkM66

Was that $20k a typo?

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

[mazspeed]

Originally Posted by 69bird

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.

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

[68protouring454]

Originally Posted by mazspeed

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?

[camcojb]

Originally Posted by mazspeed

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.

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

[mazspeed]

Originally Posted by camcojb

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?

[ProdigyCustoms]

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.

[mazspeed]

Originally Posted by ProdigyCustoms

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 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, 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?

[ProdigyCustoms]

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?

[Blown353]

Originally Posted by mazspeed

Is there a better carb hat?

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.

[TOM NELSON]

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