My experience at the dyno today...

[perry2k12]

Well today was interesting to say the least. Since last year, I added a 4lb lower, GT pumps, and a small shot to my car. Last year after a tune, my car put ~481/461. (I have not used the nitrous yet).
Today, the car was being retuned by Bob Kurgan on a dynojet. He tried many different things, but the car just would not put out more than 480 rwhp. Everybody elses car was showing very significant gains. This should be around a 520 rwhp combo, especially with todays cool outside air.

When he looked into it a little more, the RPM/gear ratio was showing that my clutch may be slipping. The power band for the RPM/gear ratio was a dome shape, dropping off the power.

He said as the car wound out, the clutch pedal was sucked down almost all the way to the floor by the end of the run. My Spec 3+ has less than 2000 miles on it.

Going off the datalog, the car is pulling in tons of air, 17 PSI strong all the way through, fuel is proper, but it isn't putting the power to the wheels.

Here is the weird part. On the street, the car feels like a new animal and I cannot detect the clutch slipping whatsoever.

I know the dyno is just a big number-maker, but it still tells me something significant could be wrong with my car.

Anybody have any ideas?? This thing has so much potential!

 

[vadorsnake04]

To me if the car is running great, showing no issues don't worry about the numbers. In the end the numbers are just that, numbers. The track will show the real numbers if you are that concerned.

 

[perry2k12]

I'm more concerned that the car didn't show any improvement on the exact same dyno. And that curve in the rpm/gear ratio is stuck in my head. I can probably get the sheet if anyone is interested.

 

[timspony]

I agree...you should be in the 520 rwhp range with pump gas (with you mods in your sig)...what was the torque??

 

[theunseenclass]

Let's see that dyno sheet

 

[05satinGT]

When your car put down 480rwhp on the same dyno that you just got tuned on? But +100, if the car runs right, is tuned properly, a/f is spot on, screw the numbers.

 

[perry2k12]

I agree...you should be in the 520 rwhp range with pump gas (with you mods in your sig)...what was the torque??

It was super low.. it said like 430 if I remember right

Let's see that dyno sheet

Let me email bob for it

When your car put down 480rwhp on the same dyno that you just got tuned on? But +100, if the car runs right, is tuned properly, a/f is spot on, screw the numbers.

it "put down" the exact same numbers as last year on the same dyno. even kurgan said he doesn't understand it.

 

[theunseenclass]

I agree dyno numbers are just that, but something is obviously not 100% correct if after all those mods you gained nothing.

 

[timspony]

What plugs? ...gap? ....FPDM (w/GT pumps)?? ...Something is not right IMHO!

 

[perry2k12]

What plugs? ...gap? ....FPDM (w/GT pumps)?? ...Something is not right IMHO!

Just installed NGK BR7EF gapped at .030 before the tune. It's a modded fpdm with the gt pumps.

He said he can tell the motor is going to make big power. It is running very well. But something isn't putting the power to the wheels. He said its sucking the clutch pedal to the floor at WOT... inevitably causing the clutch to slip. What in the world does this mean? My spec 3+ has about 2k miles on it, and I know it was installed correctly.

 

[619Cobra04]

Just installed NGK BR7EF gapped at .030 before the tune. It's a modded fpdm with the gt pumps.

He said he can tell the motor is going to make big power. It is running very well. But something isn't putting the power to the wheels. He said its sucking the clutch pedal to the floor at WOT... inevitably causing the clutch to slip. What in the world does this mean? My spec 3+ has about 2k miles on it, and I know it was installed correctly.

My RXT has 2000 miles. Still slips around 7lbs of boost. Did the with 2000 miles clutch before it. I gave up on fixing this issue and no one has a clue why it slips. I'm gonna call McLeod this week, if they will replace it under warranty or something :/

 

[timspony]

Do you have a firewall adjuster for the clutch??

 

[perry2k12]

Yes I have a firewall adjuster. The TOB is about 1/10" away from the clutch fingers. Kurgan said it's not an adjustment issue.. he said that's the best way to have it.

 

[perry2k12]

Question: Could this have anything to do with the clutch cable bracket? The bracket that bolts to the fender, in the middle of the cable has never been bolted down since I got the car. If that bracket is hanging loose, could it have anything to do with the clutch pedal sucking down like that?

 

[SVTDice]

Honestly, Your gap is a little too small for your setup, You could probably get away with .032 or even .034. But I'm guessing you put it at .030 because of the chance of running Nitrous?

 

[perry2k12]

Honestly, Your gap is a little too small for your setup, You could probably get away with .032 or even .034. But I'm guessing you put it at .030 because of the chance of running Nitrous?

Yes, I was hoping to be on a 125 shot by the end of the day... but obviously didn't end up happening.

 

[jrd699]

Question: Could this have anything to do with the clutch cable bracket? The bracket that bolts to the fender, in the middle of the cable has never been bolted down since I got the car. If that bracket is hanging loose, could it have anything to do with the clutch pedal sucking down like that?

Best way to find out......... Bolt it down :rolling: I would try that, it's cheap enough to start with. I would keep looking for solutions, cause something's wrong

 

[ZYBORG]

Dynos suck, dynos are fictional man... Unless its a comparo on the same day without changes in temperature and dyno settings, ALL other dyno sessions are worthless! You said the car feels like a beast... Thats all that should matter.

You should be able to feel a little difference in power improvement since the bew mods, if you do then i believe its all good... And let the ass kicking commence.

 

[619Cobra04]

I as well have the Firewall adjuster. The pedal has a little slack, but not enough to fall of the quadrant. I'm not trying to steal ur thred bro. But we may have the same issue minus the pedal getting sucked to the floor.

 

[perry2k12]

I as well have the Firewall adjuster. The pedal has a little slack, but not enough to fall of the quadrant. I'm not trying to steal ur thred bro. But we may have the same issue minus the pedal getting sucked to the floor.

IMO, the best way to adjust the clutch, is to get under the car with it running (be extremely careful obviously.. a lift is best) and see how close the throw-out bearing is to the clutch fingers. The TOB should be just off the fingers, and it will make contact pretty much as soon as you touch the clutch. The factory calls for 1/8th inch. I've learned that if it spins constantly, your tob will be toast.

p.s., the LDC freeplay mod helps eliminate the slack, but proper adjustment is key.