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| Build update - 4T80 3800 Turbo (Page 9/10) |
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LFiero67
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JUN 11, 12:00 AM
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Frenchrafe
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JUN 11, 01:40 AM
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Just watched your videos.
I would love to be able to get into the 10s!
Your car is really impressive!
What size tyres are you using at the rear? They seem kind of "fat" and they fill out the wheel well / fender housing perfectly.------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM
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Dennis LaGrua
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JUN 11, 03:39 AM
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Wow ! Very impressive 1/4 mile time with a 3800. Do you believw that using a GM 6T45 have gotten you into the 9's? . ------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "
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LFiero67
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JUN 11, 08:14 AM
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255/50R16 on GTP 16x8 wheels.
Dennis, I’m assuming you meant 4T65, and yes at the weight I was with the 4T65, it likely would have ran a 9, but only with a $$$ built 4t65 would it be possible reliably.
This is a stock 4T80 that I have had in the car over a year that cost 1/4 or less than my old GMRacing equipped 4T65(1” chain, aermet 100 input shaft, Z pak 3rd, etc,etc). I broke both styles of zzp input shafts and multiple 7/8” chains in less than a year with the turbo before getting the GM racing stuff. 4T80 is heavy, but so far has put up with everything I’ve thrown at it, the 4t65 didn’t even survive a month of street driving/tuning before breaking first input shaft and stretching first 7/8” chain in 2012.[This message has been edited by LFiero67 (edited 06-11-2025).]
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LFiero67
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JUN 16, 10:25 PM
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Realized I didn’t post the changes to suspension I made.
Removed bump stops in rear to give extra travel, moved up to 325lb springs vs 275lb and raised back of car about 1/2”. With this change I was able to remove all launch retard from tune. Next will be reducing the boost ramp from where I had it to more closely match what used to run.
Currently 11lb max launch, holding for 0.5 seconds and ramping to target boost in 1 second. Total time to target 1.5 sec.
Old setup, 9lb max launch (or snapped axle), ramp to target in 0.8 seconds. Total time to target 0.8 seconds.
Hoping this gets the car back to running 1.4x 60’ and possibly even get into the 1.3x range.[This message has been edited by LFiero67 (edited 07-25-2025).]
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Dennis LaGrua
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JUN 22, 04:37 AM
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| quote | Originally posted by LFiero67:
255/50R16 on GTP 16x8 wheels.
Dennis, I’m assuming you meant 4T65, and yes at the weight I was with the 4T65, it likely would have ran a 9, but only with a $$$ built 4t65 would it be possible reliably.
This is a stock 4T80 that I have had in the car over a year that cost 1/4 or less than my old GMRacing equipped 4T65(1” chain, aermet 100 input shaft, Z pak 3rd, etc,etc). I broke both styles of zzp input shafts and multiple 7/8” chains in less than a year with the turbo before getting the GM racing stuff. 4T80 is heavy, but so far has put up with everything I’ve thrown at it, the 4t65 didn’t even survive a month of street driving/tuning before breaking first input shaft and stretching first 7/8” chain in 2012.
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The 6T45 is a GM automatic transmission with 6 speeds.
6T45 GM 6 speed auto
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LFiero67
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JUN 22, 11:42 AM
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I have no familiarity or info on that trans, other than GM rated it as a “45” strength which implies I would break it even faster than a 4t65, however not having a chain, it may live slightly longer unless a hard part breaks, ie input shaft, gear, differential. In a quick search, I see they also made a 6t70, 6t75 and 6t80, which would be stronger, but weight is between a 4t65 and 4t80 at 225-231 lbs. Not sure how you would program or control the internal controller, but it’s not something I am going to be running out and trying. First gear would be completely useless for me, and clutch to clutch shifting must be re-calibrated for higher horsepower to prevent slipping and failure.
Additionally the 6t80 was only ever used in one car, making supply and support very limited, though the 70 and 75 should be more available, as they were in many GM vehicles on 3.6l engines. None of these engines use the GM metric bolt pattern, so an adapter plate would be needed.
Perhaps if someone figures out an adapter, mounts, control, and I can no longer get 4t80/parts, I might try it, but for now I am pretty happy with the results with the 4t80.[This message has been edited by LFiero67 (edited 06-22-2025).]
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LFiero67
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JUL 25, 11:46 PM
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Ran the 100’ Dash at local Street Machine Weekend a few weeks ago. Tried launching a bit harder and ended up doing a 100’ burnout. Going to have to play with the suspension and tune a bit more to get this thing launching like it should.
Tried a bit slower boost ramp on second run and it was a bit better, but still lost the tire, no video of that run.
100’ Dash Run 1 Video[This message has been edited by LFiero67 (edited 07-25-2025).]
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LFiero67
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AUG 16, 04:15 PM
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Got the car on a scale today. Scale was reading 20kg when I rolled on, not quite full tank of fuel, with driver. She is a pig lol.
1510-20 = 1490 kg = 3284 lbs
Slightly lighter than I was expecting, but within 50lbs of my estimate.
Video on scale:
https://youtu.be/pwgjZXkIKtE?si=_dbYlyjCA-Bum6zX
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10.007 @ 135.54MPH. <-- Video
Best 60' 1.42
Best mph 138.82
Billet 6262 Precision turbo, PT1001 intercooler, ST1 cam, 140lb springs, comp pushrods, HV3, stock L32 bottom end and heads.
Old M90 XP Cam time -
11.425 @115.60
1.543 60'[This message has been edited by LFiero67 (edited 08-16-2025).]
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LFiero67
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SEP 13, 08:34 PM
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