There was this dude at the Superbowl party I was at who was telling me about his 8.1L Avalanche and how he blows Mustang GTs off the road all the time, etc, etc.,

Anyway, this had me thinking, has anyone tried to drop this big block in an F-Body? I know LS1s are potent enough to make plenty of N/A power, but does the 8.1L have any potential in our cars, and will it fit?

Well, there's a guy over in the Tampa area with a 555ci BB in his '98 T/A so I know it can be done...but I have no idea how much work is involved in the swap (I know it's not easy/simple).

A big block swap is a topic that has come up before so I'd say do a search here and at ls1tech.com and see what you find.

Hardest part is just getting the exhaust to fit, everything else is cake.

even if it does fit i think it would be easier, faster, and cheaper to just go forged internals and some sort of FI with the motor you already have

My older brother has the 2001 Chevy Quad cab truck 2500HD. It has the 8.1L in it. It sucks major gas! He ran it at the track last sunday (HRP) and it ran a 16.7 in the 1/4. It feels like it has alot of power, but it takes alot more to get a 7440lbs truck moving.

theres lotsa fast F-bodys here!

actually, 0-60 between the 5.3 Avalache and the 8.1 Avalanche are the same. There is no more than a 10th difference between them (which can be attributed to anything).. both in the mid 8 sec 0-60 range.

The 8.1 has tons of more tq especially on the lower end, but the larger axles and drivetrain and other HD stuff add alot more weight.. about 1000 lbs more!

So in the end, the 8.1 and 5.3 (which has a sweet midrange) are about the same in acceleration.

5.3 uses lot less gas when driving around town with no significant load, but obviously the 8.1 has a much easier time towing larger loads, with higher capacity.



back to f-bod's:

Another alternative is to resleeve/bore and stroke out your LSx engine to 7L's..

The 572ci big block has been stuffed into a 98+ camaro to create the one and only TRUE ZL1 supercar.

It was actually a '94...just had a '98+ fascia.

'94, '98+ same thing, I know...just thought I'd throw that out there.

Meh. In a drag-only car, stuffing a BB in a F-bod would be OK, but that's a lot of weight and would make an already cramped engine-bay worse. I'd rather build a 400+ ci Gen III...

AAAAActually.... it was a 93.

8.1L F-body sounds good to me but my theory is "theres no replacement for displacement" id like to see it done...

The year of the car doesn't really matter because the only thing left from the factory after the install were the body panels. LOL