Mods done to my LT1
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Mods done to my LT1 The only thing I am not thrilled about is the 3.73 gears.
It's OK in town but not the greatest for extended highway travel. I don't race or anything, just looking for a normal daily driver. Will probably swap them for 3.23 or at the very least for 3.42 if 3.23 does not work.
1996 Buick Roadmaster Grand Sport wagon
LT1, LT4 valve covers, Bee Hive valve springs, Comp Cams Pro Mag Full Rockers 1.6, custom headers
More details on the Cam and the TC:
Competition Cams Comp cam LT-1 LT-4 Chevy 93-96
* Application 1993-1996 Chevy 350 LT-1 and LT-4 engines
* Power Range 1000-5000 RPM
* Idle Quality/special requirements-Best for original LT1 with stock computers
* Valve Lift 500/510
* Adv Duration 266/276
* Duration @.050 210/220
* Lobe Centerline 114
TC:
GM Big Shot 12LS
This converter is primarily used in Street Rods that are slightly modified and always street driven. The Big Shot 12LS is an excellent converter for long distance cruising with mild performance increases, good lockup, and minimal MPG loss. This slightly higher than stock converter produces good idling with mild street rod designed cam shafts. Rear ratios should be in the range of 3.23 to 3.73.
Stall speed range: 2000-2400 rpms.
It's OK in town but not the greatest for extended highway travel. I don't race or anything, just looking for a normal daily driver. Will probably swap them for 3.23 or at the very least for 3.42 if 3.23 does not work.
1996 Buick Roadmaster Grand Sport wagon
LT1, LT4 valve covers, Bee Hive valve springs, Comp Cams Pro Mag Full Rockers 1.6, custom headers
More details on the Cam and the TC:
Competition Cams Comp cam LT-1 LT-4 Chevy 93-96
* Application 1993-1996 Chevy 350 LT-1 and LT-4 engines
* Power Range 1000-5000 RPM
* Idle Quality/special requirements-Best for original LT1 with stock computers
* Valve Lift 500/510
* Adv Duration 266/276
* Duration @.050 210/220
* Lobe Centerline 114
TC:
GM Big Shot 12LS
This converter is primarily used in Street Rods that are slightly modified and always street driven. The Big Shot 12LS is an excellent converter for long distance cruising with mild performance increases, good lockup, and minimal MPG loss. This slightly higher than stock converter produces good idling with mild street rod designed cam shafts. Rear ratios should be in the range of 3.23 to 3.73.
Stall speed range: 2000-2400 rpms.
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It wouldn't be an equal trade as I got new Eaton Posi + new gears and it's dead silent. They really have only 10K on them.
I am going to have someone tear into it and install new gears, and if you are interested in the 3.73 that come out, I can contact you then.
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Problems with 3.73:
Too high RPms at highway speeds. 2600-2700 is not uncommon.
Too noisy engine due to high RPMs. The last time I drove highway it was 13 hours interstate driving and it drove me crazy.
Terrible MPG, not even getting to 18mpg on the highway. Seems the MPG drops like a rock between 70-80mph. Keep it around 55 for the best MPG.
Switch to a higher gear and gain 2-3MPG easily, which is significant as these engines don't get that good MPG to begin with. I think I would be happy with 21mpg. I wouldn't consider going higher than 3.23 or 3.08 in the worst case.
Now with 2.56 gears, possible to do 25MPG which is insane for a large B-body auto with a V8 but they really s**ck in town. I had 2.93 and could barely tolerate them. I think with 3.23, the city MPG might stay the same.
3.73 gears are great for towing. Otherwise running empty and turning 300RPMs higher at 70 than 3.23 (it's 2300 vs 2000 RPMs) seems like a waste.
With 3.08 or 3.23, I have more top end speed available than with 3.73. Seems to me like 3.73 in effect make the car slower on the highway.
Now if I had a 6 speed M/T, I would want 4.10.
Too high RPms at highway speeds. 2600-2700 is not uncommon.
Too noisy engine due to high RPMs. The last time I drove highway it was 13 hours interstate driving and it drove me crazy.
Terrible MPG, not even getting to 18mpg on the highway. Seems the MPG drops like a rock between 70-80mph. Keep it around 55 for the best MPG.
Switch to a higher gear and gain 2-3MPG easily, which is significant as these engines don't get that good MPG to begin with. I think I would be happy with 21mpg. I wouldn't consider going higher than 3.23 or 3.08 in the worst case.
Now with 2.56 gears, possible to do 25MPG which is insane for a large B-body auto with a V8 but they really s**ck in town. I had 2.93 and could barely tolerate them. I think with 3.23, the city MPG might stay the same.
3.73 gears are great for towing. Otherwise running empty and turning 300RPMs higher at 70 than 3.23 (it's 2300 vs 2000 RPMs) seems like a waste.
With 3.08 or 3.23, I have more top end speed available than with 3.73. Seems to me like 3.73 in effect make the car slower on the highway.
Now if I had a 6 speed M/T, I would want 4.10.
Last edited by dogma; May 17, 2010 at 12:13 AM.
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