Strange problems at the track (long)

[TType85]

I took my car out the local 1/8th mile track..... Combo is in the signature. Last week with a stock IC I ran 8.0@92.00 at 20psi. The car pulls like MAD on the top end. That run I was at the back bumper of a LS1 (ran 8.0@84) at the 330' mark and we were dead even at the 660' mark.

All runs made on JC Race Chip
Run 1:
17psi, 42psi FP, shifting at 5800
o2's at the top end were mid 700's
less than 2deg of retard at the top end
7.9@92.91

Run 2:
20psi, 45psi FP, shifting at 5800
o2's at the top end were mid 700's
less than 2deg of retard at the top end
8.0@92.22

Somthings not right here.

The car was still pulling at 5800rpm. It will pull to 6K before it runs out of breath. The air was about the same temp and quality (2600ft) both days. I've hit a wall.

Looking at the timeslips from my old 85 combo, it ran 92 in the 1/8 and 117 in the 1/4. I'm beginning to think its not the motor or the tuning thats the problem.

The transmission is a 85 Turbo unit with the correct valve body. It was rebuild a while back. The converter was rebuilt about 1yr ago (only has 15-20 passes and 7K miles). The conveter will brake stall to 3200rpm at 0psi. The rearend is stock non-posi (the reason for the slow ET's). The tires are Nitto 275/50-15's which are too short for the car. The car comes up on boost quickly but softly (unlike my TA-54 that hit hard and just spun the tires).

I've had the suggestion that the converter might be the culprit, but that is an expensive part to "try" to see if its the problem. Has any one else had any similar problems? any suggestions?

 

[UNGN]

Culprit in what?

an 8.0 with a 92 mph trap speed indicates a 2.0 or worse 60 ft time.

With a 92 mph trap you should be running 7.5's with a 1.65-1.70 60 ft.

Your post didn't mention anything about your 60 ft.

If I had to guess, I'd say your propblem is probably that it is pig rich on the bottom.

You have a lot of mods there to be running 8.0's. I would be pissed when I'd only run 8.0's after putting on a TA49 and Blue Tops. Have you tried slapping in some race gas and turning up the boost so it leaves like a bat out of hell and doesn't look back? You wouldn't even need a whole tank, just enough for say 20 psi.

 

[TurboDave]

Dya think the LT70 Turbo might be just too much for your converter. Or put another way, probably not enough converter for that BIG turbo?

That would be my guess anyway, judging from your description of a soft 60' roll out.

Heck even my -6 pump Precision doesn't stall any higher than 3200 at 0psi

 

[TType85]

You have a lot of mods there to be running 8.0's. I would be pissed when I'd only run 8.0's after putting on a TA49 and Blue Tops. Have you tried slapping in some race gas and turning up the boost so it leaves like a bat out of hell and doesn't look back? You wouldn't even need a whole tank, just enough for say 20 psi.

the 8.0's are not the problem. I know why it only et's like that. I can't leave with anymore than 0psi or it will blow the tires away. I was running race gas and 20psi, it ran within .5mph of the run at 17psi.

an 8.0 with a 92 mph trap speed indicates a 2.0 or worse 60 ft time.

With a 92 mph trap you should be running 7.5's with a 1.65-1.70 60 ft.

Your post didn't mention anything about your 60 ft.

Actaually in my friends car using the same tires, (60-1,v2,55's,thdp,etc) the car would 60' in the 1.9 area and ran 7.5@92. The car 60' 2.0's CONSISTANT. No posi = no traction.

Dya think the LT70 Turbo might be just too much for your converter. Or put another way, probably not enough converter for that BIG turbo?

That would be my guess anyway, judging from your description of a soft 60' roll out.

Heck even my -6 pump Precision doesn't stall any higher than 3200 at 0psi

I think its enough converter. The car will spool up fine, if I had traction (posi, slicks) I could leave under boost. The car is at full boost before I get through the 60' lights leaving at 0psi. It will 60' 2.0 all day that way. i had a TA-54 with a .85 PTE housing on it and it would spool quicker, but it was useless because it would hit so hard it would blow the tire away at anything under 45mph.



The problem is why can I not go any faster than 92mph? 17psi, 20ps, even on a street chip 2 weeks ago I went 92mph.....

One thing I was thinking is that the fuel filter I ended up using since I did the conversion could be a problem. I used a filter off a 87-93 Mustang 5.0 (has nipples so I could clamp it to the fuel line off the tank.

 

[UNGN]

Why don't you stop buying too big turbos and invest in a posi-traction.

I doubt seriously you are running into a "wall" at 92 mph. Atleast it's no wall that more boost can't smash through.

If you trust your O2's check your FP during a run and see if you regulator is working properly or someother fueling problem.

 

[TType85]

Originally posted by UNGN
Why don't you stop buying too big turbos and invest in a posi-traction.

I doubt seriously you are running into a "wall" at 92 mph. Atleast it's no wall that more boost can't smash through.

If you trust your O2's check your FP during a run and see if you regulator is working properly or someother fueling problem.

Got a good deal on the big turbo

I did buy a posi off of someone on this board, but it was bad, looked like it was sitting in water, spider gears are chipped. Live and learn.....

I would think that going from 17psi to 20psi I would see some increase, the runs looked good on DS. I will check the FP under boost.

 

[TType85]

I confirmed the FP does rise with boost. set at 38psi it goes to 58-60 at 20psi (still have 110 in the tank).

 

[TurboDave]

There's only so many feet to get that thing up and going in 1/8 mile Doesn't matter how much power you have or can make, if have to ***** foot it out of the whole because it's a peg legger..... Well, you get the picture. For the money you got in that turbo, you could almost have a brand new off the shelf GM 12 bolt under that car.

 

[TType85]

Originally posted by TurboDave
There's only so many feet to get that thing up and going in 1/8 mile Doesn't matter how much power you have or can make, if have to ***** foot it out of the whole because it's a peg legger..... Well, you get the picture. For the money you got in that turbo, you could almost have a brand new off the shelf GM 12 bolt under that car.

I bought a posi off a board member here and it turned out to be a POS... The turbo wasnt that expensive

the last run I made last night, I uncorked it, added a little FP since I knew the boost was going to go up. I left, spun, let off, got into it, had bad knock at 1/2 track, let off a little, got back into it, still knocked (going through the traps) Boost was about 24, car ran 8.1@92.2..... guess i'm stuck at 92mph till I get the rear worked out...

 

[FJM568]

Heheh...hook a ricer to the back bumper for more traction!!! One of these days, we'll find out something they are good for...

 

[TType85]

Originally posted by FJM568
Heheh...hook a ricer to the back bumper for more traction!!! One of these days, we'll find out something they are good for...

LOL

Last time out, car was running 8.0@92 at 20psi through the stock IC. i had a LS1 get a hole shot on me (2.0 vs 1.7) I was at his back bumper at 330' out, a bumper ahead at the end of the track.... he ran 8.1@84

 

[TType85]

after going over this in the chat room, I think we may have found the problem.....

when I adjusted the TV cable, I brought it IN 2 clicks which was the WRONG way I guess for firmer shifts. Also would make the trans slip.... which could cause the car not go any faster....

DOH!

 

[TurboDave]

Chris, you're not going to go any faster till you get the obvious problem resolved..... Traction.

 

[TType85]

Originally posted by TurboDave
Chris, you're not going to go any faster till you get the obvious problem resolved..... Traction.

Thats next on my list.... With the TV cable adjusted correctly the car will now spin the tire (275-50-15 Nitto DR) above 17psi in 1st gear. I think its putting a little more power down to the ground.

 

[STG2LTD]

Hey Chris,

I spoke w/Tim Lee on Saturday. He's got a used TR posi unit for ya $200. Let him know if your interested. The bearings are fresh and the unit is ready to install.

Your definately wasting time/mph by not being able to leave hard.

If ya get the posi unit I'll get ya set up..........I've got this Friday off......hint....hint...Make sure you get a gasket/gear lube/posi add.

CYA,

J. Hall

 

[TType85]

Sold!

I'll call him monday and get the cash to him and get it!

Thanks Jason!