i am thinking of using this engine instead of a ls1/2/6 just beacuse it is original and i can get one at a pretty low cost. anyone have and pros or cons on this? it will be going into a 66 el camino, also was wondering if a t56 will work with it.

 

I was going to do this in a 99t/a. but it was gonna be a pain to shoe horn it in. it is totally different than the ls1/2/6 engines in that it is based on a mark V platform. which is basically a big block motor with a distributorless igntion. I was thinking the same thing that they are cheaper than the ls1/2/6's out there. plus big cubes. if you are doing a fuel injected setup then you might need wiring harness, ecm from the truck's. or get the edelbrock carburated setup for the ls1/2/6. that would work. hope this helps

 

All the 8.1's I have seen were peddle by wire. Plus I do not beleave a T56 will work. 8.1 is its own animal. And from what I have seen there are not to many ones with standard transmission. If this going it to a car then there well be a good deal of custom work.

 

My buddy has one in his 70 Chevelle. Can we say torque? There was a member on here that ran one in his 67-72 Chev shortbox!

-Matt

 

yeah, pretty much you must treat it as far as interals go as an old school mark series big block. the only difference is that is has a ecm controling the ignition. kind of a half breed. part LS motor, via the distributorless ignition. and part big block for everything else.

 

Whats the advantage of going the 8.1 route in our cars??? Never heard of people doing this before now?

 

in an fbody it will take tons of fabrication to shoe horn it in. but above badtexas states that it is going into a 66 el camino. tons of room to put it in.

 

you got my vote

 

edelbrock kit wont work for the 8.1... the intake is different. tho the electonics may work.

you can bolt a t56 to it with a custom flywheel setup.
the bellhousing pattern is the same.
if there was an allison behind it, you can simply remove the adapter.

 

If you can make it fit, do it. We have a few flatbed tow trucks and have had the 8.1's with a 4L80E and now an Allison trans. Truck we have now weighs about 18k lbs loaded w/2 cars and it STILL pulls hard... I drive the hilly PA Turnpike in Western Pennsylvania and the only way another commercial truck can pass me on the big hills is if I take my foot off the gas!

Can't say enough good things about that engine!

 

i know one bad thing.... the gas milage!
otherwise, its a workhorse... hard to beat it (gas motors of course)

 

about the T56 behind the 8.1. i'd try to see if a stock LS1 flywheel will bolt to the 8.1's crank flange. GM is known for making stuff interchangeable between engines. I know the 8.1 is a smaller bolt circle the traditional, but it might just be the same as LS1. they are all internal balance engines, so you might just be able to "bolt up" a t56 to the 8.1 engine. that would be neat!

GM rated the 8.1's around 335 HP and 480 ft lbs, that was with manifolds, cats, emissions. in a 66 el you should have headers and open exhaust. watch the oil pan for ground clearence.

the 8.1 in my 67 had the best "seat of the pants" feel of anything i've ever had. the torque is unreal from those beasts.

I even swapped in a hydrollic roller camshaft (zz502 crate engine cam) into the 8.1 with a set of ARP rocker studs and ran aluminum BBC rockers.

now this changes the firing order and the stock computer wont be able to handle it with SEFI and coil per plug. i was running bank to bank fuel injection and wasted spark, so the firing order change made no difference to me.

you'll find the 8.1 WILL BOLT UP anywhere a traditionl BBC was bolted. ony difference is all the fasteners are Metric Thread. the 8.1 is a TALL DECK similar to the 427 truck motors. all internal specs are the same, rod, main, even bore size. the 8.1 uses an all new 4.370 stroke and traditional 4.250 bore making 496 cu in at standard bore. 4.370 stroke is the same stroke used in GM's new ZZ572 Crate engine.

be ware if you go cam swap or want to turn many rpm. the pistons are weak in the 8.1's. i've personally seen two of them with exploded pistons. one was in my pickup, it went boom at about 5200 RPM at WOT. another one i bought to replace that one, was had also seen the same fate. I have pictures on my website of all I did.

If you got your hands on a 8.1 cheap, i'd buy it. then get you a 4.25 stroke forged crank, some eagle hbeam rods, and a good forged piston. they would all fit. the block is a one peice seal design, but i've seen seal adapters to use an old two piece seal crank.

good luck! if you dont buy the 8.1 let me know, I might dabble with one again!

-Brendan

 

i am building a cruiser/daily driver so the WOT will be limited, a jeep mag did a write up of one installed in a jeep or blazer or something and without emissions and using headers the got something like 420 hp and just over 500 lb-ft<---should be plenty to haul a lightened 1966 el camino around town. my el camino originally had a 396 in it so i am guessing this beast should fit.

 

You would be better off with an LS1 or 6.0 IMO. You can make 400rwhp quite easily with a simple cam upgrade, ported TB, and good exhaust with retuned PCM. Much better gas mileage as well and no custom crap to put a T56 behind it.

I towed a 29' Scarab powerboat behind my cousins '04 2500 4x4 8.1litre truck going about 70-80mph on the highway and was getting 4mpg. If I wasn't within 20 miles of a gas station at a 1/4 tank I was screwed. Those big trucks come with tiny gas tanks. He should've gotten a Duramax!

 

True, as mentioned in a few posts, the 8.1's are a little thirsty! We usually get between 5 and 7mpg loaded on the highway between 70 and 75mph (depending on how heavy the load is) and almost 10mpg empty. Don't forget, this is on a pretty heavy truck... prob around 11k lbs empty. I firmly believe that the way you gear it and what gearing your trans has will have a lot to do with the gas mileage.... but it's still not going to be as efficient as the GenIII smallblocks.

 

If the 8.1 is the old 1 piece rear seal design and uses a traditional flex plate from the later tradional SBC. I would think a LT1 T56 would bolt right up.