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Why is magnum TPI so slow?

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Old Aug 13, 2001 | 10:48 AM
  #1  
GofasterFirebird's Avatar
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From: Warsaw, Indiana
Car: 1991 Firebird
Engine: 427 LSX
Transmission: Turbo 400
Why is magnum TPI so slow?

Sure it is quick but its mph is terrible in my opinion. Any comments??
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Old Aug 13, 2001 | 11:16 AM
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FormulaJoe's Avatar
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From: Stillwater, Oklahoma, USA
Seems like a good example of what happens when you throw the wrong combination of parts together.

------------------
L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.
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Old Aug 13, 2001 | 12:27 PM
  #3  
86ZZ4's Avatar
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From: tulsa ,ok , usa
havent kept up with it, what did it run?

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86 z28 zz4 ssm lift bars ,3.73 simesed runners and a traction deficient 13.707@101.02,on a 2.16 60 ft on 295/50/15 junk street rubber ,best MPH run 13.82@102.7,69 AMX,390 4 speed sticky tires and other stuff..12.94@102.3
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Old Aug 13, 2001 | 01:25 PM
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FormulaJoe's Avatar
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From: Stillwater, Oklahoma, USA
The ET was great but MPH wasnt so hot. I think it ran like a 13.0 @ 103 or something like that on slicks. The slicks explain the good ET with the low trap speed.

------------------
L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.
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Old Aug 13, 2001 | 02:25 PM
  #5  
BadSS's Avatar
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From: USA
There was a problem with the engine. I wonder if they ever did a compression check or leak down test on the engine before bolting all that stuff on.
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Old Aug 13, 2001 | 02:56 PM
  #6  
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From: tulsa ,ok , usa
what all kinds of mods were done to it?and what was wrong with the motor?
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Old Aug 13, 2001 | 11:57 PM
  #7  
FlashGTA
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Rod Knock!
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Old Aug 14, 2001 | 06:31 AM
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From: Key West, Florida!
Car: 89RSconvtZZ4TPI
Engine: ZZ4TPI
Transmission: 700R4 TRIPP TRANNY
If I remember from last issue, they had massive engine failure and are going with a 383 or 396. Just the simple build up all us TPI guys can do


------------------
Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!
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Old Aug 14, 2001 | 11:11 PM
  #9  
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From: Hinesville, GA USA
Car: '86 IROC-Z/'94 Z28
Engine: 350 LT1/382 LT1
Transmission: 4L60-E/T-56
Axle/Gears: 3.45/3.42 (soon 4.10)
I think your problem is that the motor is being (or was being) used N/A for now, but was built for a supercharger. It had 9.0:1 compression with aluminum heads. That lowers peak power. Also, they used the TFS 23 degree head, a head I've heard doesn't work great with LTR TPI's (although I'm sure it still works decently). Probably wasn't the best choice. I would've used some AFR 190's or TFS TW heads. The cam was also relatively mild with I think a 114 LSA.

Anybody know what they're going to do with the old parts? I'm interested
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