LS1 Conversion Complete 72 grand Prix
02-05-2008, 06:12 PM
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LS1 Conversion Complete 72 grand Prix New crate LS1 installed in my 72 Pontiac grand Prix. It's a 1998 Corvette LS1 service replacement crate motor. The Corvette oil pan fit without crossmember modifications. Just had to weld on a couple of gussets to the rear of the crossmember. Used adapter plates and the stock pedistal mounts. I thought the G body and A bidy were the same regarding the frame, but discovered otherwise. The G body frame crossmember to several inches forward. Have a 700R4 with a 2:37 12 Bolt LSD.
Last edited by Frnichols; 02-10-2008 at 01:25 PM.
02-05-2008, 07:09 PM
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wow! great car! my uncle had a 1970 SJ-code (I think thats what it was, it was a factory 455 car) and a 1971 that he put a built 455 in to that ran 13.00 @ 108. I bet theres a lot of weight off that front end with that big poncho out of there! your mileage is fantastic too. how does it sound?
02-05-2008, 07:40 PM
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It had a great running 455, but I couldn't leave it alone. Got 15 MPG on the highway and 12 in town. Had to cut one coil off the front springs. The crossmember could not have taken a notch for the AC. Would have had to cut it all the way across, but was saved by S&P.
02-05-2008, 07:54 PM
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Hey great job! yeah.. I had Hotchkis TVS system and B-body spindles, it should have dropped it 2" to 2 1/2".. but after the swap.. it is about stock height !.. going to cut a 1/2" off later this winter.. That is how much weight different there it.
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02-07-2008, 04:08 PM
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Sweet!!!!!!!!!! cruiser, How does it feel compared to the 455? Just curious I sold my olds 455 yesterday after changing direction and going with a ls1 in my f-85 cutlass.
02-07-2008, 04:33 PM
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I think in a race between the two, the LS1 would be ahead at 1/8 mile and the 455 would win the quarter. The 455 weighs over 600 pounds fully dressed and the LS1 is almost half of that. That's according to numbers found on net searches, not weighing.
The fuel injection is crisp, smooth, and constant. It starts quickly without all the choke problems. The 455 had more torque and certainly a greater stroke/power band. But I wanted reliability, mpg's, and the computer adjustments when changing elevation. It's a cruiser with 2:73 gears. With the 700R4 in lockup @ 75 mph, it runs 2,000 rpms. So a car that weighs a little less than 4,000 pounds can get over 20 mpg.
I also dicided to modify the existing gas tank instead of having one made. Got a kit with a Walbro 340. The benefit was to retain the 26 gallon tank. Cost a lot to fill up, but it now has an incredible range for about 500 miles on the highway.
Just installed a Dakota Digital tach adapter and it works well. Hadda call the tech line though. It's one of those deals where you have to turn key, holddown a button, dip a switch, count blinking lights, all while standing on one foot with my tongue to one side. But, it works.
The fuel injection is crisp, smooth, and constant. It starts quickly without all the choke problems. The 455 had more torque and certainly a greater stroke/power band. But I wanted reliability, mpg's, and the computer adjustments when changing elevation. It's a cruiser with 2:73 gears. With the 700R4 in lockup @ 75 mph, it runs 2,000 rpms. So a car that weighs a little less than 4,000 pounds can get over 20 mpg.
I also dicided to modify the existing gas tank instead of having one made. Got a kit with a Walbro 340. The benefit was to retain the 26 gallon tank. Cost a lot to fill up, but it now has an incredible range for about 500 miles on the highway.
Just installed a Dakota Digital tach adapter and it works well. Hadda call the tech line though. It's one of those deals where you have to turn key, holddown a button, dip a switch, count blinking lights, all while standing on one foot with my tongue to one side. But, it works.
Last edited by Frnichols; 02-10-2008 at 01:26 PM.
02-07-2008, 06:48 PM
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I'm getting stoked now, my 3,100 lb 65 cutlass has a 3.08 rear. I can't wait. I have driven (2) 2002 ss 6sp and one 1998 auto. They were wicked in stock form. The 1998 was an auto with converter, cam,heads, and rear gears. The boys in Benbrock did it. It was scary wanted to go sideways when it shifted.
02-08-2008, 10:36 AM
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I bought the harness and CPU from Howell. They programmed the deal and shipped to me for a little over $1,000. No problems and they've responded well to technical questions. Didn't want a one-size-fits-all deal, cause they too often don't. This was custom made/programmed to my specs.
http://www.howellefi.com/shop/custom...s.php?pageid=6
http://www.howellefi.com/shop/custom...s.php?pageid=6