4.8L or 5.3L swap! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Cap'n Hook · 11-09-2003, 02:23 AM

Anyone done a 2000 and up 4.8L or 5.3L and tranny swap into one of our Blazer/Jimmy 4x4's. Just wondering, cuz I think it would be cool to be able to get that good gas mileage like I get in my '00 GMC ½ton extended cab, 20+ mpg.

And the driveability and cold morning starts would also be great. Not that mine doesn't start on the cold mornings, but EFI is a wonderful thing, isn't it?

bpmcgee · 11-09-2003, 02:33 AM

I agree that EFI is great. I'm using a Holley Pro-Jection TBI system on my 71 Blazer with great success. Starts fine in any weather, and with the old engine was giving more than 10% better mileage than the carb which it replaced.

The engine I just dropped in is a 76 block with Pro-topline aftermarket Vortec heads and a roller cam. This, except for TBI instead of EFI is almost exactly what you'd get in a modern 5.7. I haven't driven it enough to know the mileage, but I'm shooting for 18 highway. Should be workable since my old 7-banger got 13.

Brian

Cap'n Hook · 11-09-2003, 03:17 AM

I guess I should not complain about the q-jet on my '72 Jimmy! It idles 10 times better than the 4.8 EFI in my '00 and starts without a blink on cool mornings, and averages about 13 mpg approx. But with a 3 speed auto, this Jimmy will never see anything close to the 20-22 mpg the '00 will get!

JayDubBlazer · 11-10-2003, 05:09 AM

I thought about it, or I guess dreamed about it. But if I were going to to an EFI swap I would probaly go with a LS1 or LT1. But I would love to see this done, especially with a truck that has 4wd.

K5KRAZIE · 11-16-2003, 06:55 AM

I don't think it would be a huge problem to achieve. I know the Toyota guys have been using that motor almost since it was introduced.......

ljbear · 11-17-2003, 12:00 AM

I don't think it's a bolt in like the rest of the small block family. I talked to a guy that did it in a pckup and he said the motor mounts are different. He had to modify the towers and weld in the mounts from the 5.3.

11-09-2003, 02:23 AM	#1
Cap'n Hook Workin to live... Join Date: Jun 2003 Location: Texas Hill Country Posts: 261	4.8L or 5.3L swap! Anyone done a 2000 and up 4.8L or 5.3L and tranny swap into one of our Blazer/Jimmy 4x4's. Just wondering, cuz I think it would be cool to be able to get that good gas mileage like I get in my '00 GMC ½ton extended cab, 20+ mpg. And the driveability and cold morning starts would also be great. Not that mine doesn't start on the cold mornings, but EFI is a wonderful thing, isn't it? __________________ Jason

11-09-2003, 03:17 AM	#3
Cap'n Hook Workin to live... Join Date: Jun 2003 Location: Texas Hill Country Posts: 261	I guess I should not complain about the q-jet on my '72 Jimmy! It idles 10 times better than the 4.8 EFI in my '00 and starts without a blink on cool mornings, and averages about 13 mpg approx. But with a 3 speed auto, this Jimmy will never see anything close to the 20-22 mpg the '00 will get! __________________ Jason

11-10-2003, 05:09 AM	#4
JayDubBlazer go cyclones Join Date: Jun 2003 Location: Ames, IA Posts: 1,885	I thought about it, or I guess dreamed about it. But if I were going to to an EFI swap I would probaly go with a LS1 or LT1. But I would love to see this done, especially with a truck that has 4wd. __________________ Wes PROJECT OLE GREEN 1972 Blazer 4X4 350/700R4 2017 Silverado LT

11-16-2003, 06:55 AM	#5
K5KRAZIE Registered User Join Date: Oct 2002 Location: Wa. State Posts: 352	I don't think it would be a huge problem to achieve. I know the Toyota guys have been using that motor almost since it was introduced....... __________________ TRUCKS '72 K5 '06 mega dually

11-17-2003, 12:00 AM	#6
ljbear Registered User Join Date: Jan 2003 Location: Emmett, Idaho Posts: 858	I don't think it's a bolt in like the rest of the small block family. I talked to a guy that did it in a pckup and he said the motor mounts are different. He had to modify the towers and weld in the mounts from the 5.3. __________________ Larry 72 Chevy SWB 4x4 71 Chevy SWB 4x4 My Work Truck "Don't confuse enthusiasm with capability"

11-09-2003, 02:33 AM	#2
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	I agree that EFI is great. I'm using a Holley Pro-Jection TBI system on my 71 Blazer with great success. Starts fine in any weather, and with the old engine was giving more than 10% better mileage than the carb which it replaced. The engine I just dropped in is a 76 block with Pro-topline aftermarket Vortec heads and a roller cam. This, except for TBI instead of EFI is almost exactly what you'd get in a modern 5.7. I haven't driven it enough to know the mileage, but I'm shooting for 18 highway. Should be workable since my old 7-banger got 13. Brian



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