1FST99Z

iTrader: (9)

Just thought it was a good Idea. yeah yeah I know it is heavier and I can get more power out of a turbo ls1 or a solid cam 346 or 408 but I just like to be difficult. what mods would be needed to make it work. I know the block is a tad bit longer but the new ls2 h2o pump is shorter also bmr makes a big block k-member so that shouldnt be a problem. any information would be greatly appreciated. also if anyone knows where I can pickup an 8.1 as well that would be greatly appreciated...

59chevyapache

i dont know where you could pick one up but its not an ls1 based engine its just a fuel injected big block i cant remember what generation though.

Stu Cool

iTrader: (13)

The 8.1 (496 cu in) is a Mark IV based motor (366, 396, 402, 427, 454, 496, 502). It is installed in the 2500 and 3500 and bigger trucks. You can buy a 502 crate motor from GM Performance and if you really wanna go nutz, they also have a stroked out 572 cu in version that makes 572 hp in the street version and 700 plus in race trim. You can get them all ready to run from FI or carb to pan, or in various stages of finish.

http://www.gmgoodwrench.com/perfpartsjsp/home.jsp

Pat

1FST99Z

iTrader: (9)

thanks, but I still am clueless to why they still use the same style intake manifold, the same coil packs.throttle body,MAF, but it is different??? what is the difference between the mark IV and the LS based engines???

Ryan K

iTrader: (11)

The engines are pretty much completely different apart from the things you listed. It is physically much larger externally. It doesn't share the same motor mounts or headers or any thing. It is a Big Block Chevy vice a Small block vice LSX...

Stu Cool

iTrader: (13)

Check out this picture:

http://www.gmc.com/yukon/enginesxl_p...sp?engine=8100

While the EFI, and coil seem similar the basic motor is quite different. Check out the size and shape of the valve covers. I think they have adapted some of the same external technology used on the Gen III small blocks to the older big block design.

In the old days, Small Block and Big block Chevys could use the same distributor and ignition pieces, and they both could use Quadrajet carbs, but their internal parts and design were totally different. I think the same thing has happened here.

Pat

Speartech

iTrader: (14)

The 8.1 is a big block so none of the physical parts will interchange with the LS1, but it DOES use the LS1 electronics.

We've got a brand new 8.1 in stock if you're interested! Fully dressed with harness, computer, accessories, starter, etc. Runs like new (as it should)!

SmokingWS6

iTrader: (1)

A more intresting conversion would be to take a BBC Camaro or Abody and slap on all the external 8.1 components on the 396 or 454

Remington H.

iTrader: (2)

Well, that would be pretty sweet, but the 8.1 and ls1 are from the same family. Not the same motor by any means, but quite alike. Of course internally they are different, thats bc its a big block. The 6.0 and ls1 have differences internally too, that doesnt mean its not alot like the ls1. The 8.1 is the big block of the new chevy engine family. 4.8, 5.3, ls1, 6.0, and now 8.1. They still use ls1 electronics like previously stated, they also are a distributor-less ignition. And although I havent opened one up yet, I am pretty sure it has a 6 bolt mains too. If not, then thats one difference. And it does have the new ls1/ vortec style head, just a little bit larger version. BTW have you seen some of the power these beasts have been making, I forget who has a mild heads/cam package for it worth close to 550 hp . And I am pretty sure you wouldnt be able to bolt anything from an 8.1 to an old school bbc. Maybe the header bolts are the same size??

Remington

SmokingWS6

iTrader: (1)

The 8.1 is a Mark IV big block(old school). Mechanically it shares nothing with the lsx series motors. Just perhaps the electronics and a similar intake manifold design. Being a MK IV any bbc heads should be interchangeable assuming you had an intake manifold to match up to it.

8100hammer

just to let you that, the cam gear still spins the oil pump. But have been wondering about the heads. If one could put older BBC head, have thinking about a ram jet conversion, and just grafting engine controls to the ram jet manifold. Which would make a good cheater engine, as nobody know about this motor in the auto world. Marine world seems to be popluar. But I have heard the head bolts location have change, not to mention that cooling system in the heads is different.
Also rods are stronger in the older BBC.
8.1 weak points are in the rod and wrist pin (non-floating type), and piston.
Has anybody compared head gaskets, or have pics of them side by side??

Project GatTagO

iTrader: (7)

The 8.1 is actually called a Mark VI, not Mark IV. The differences are subtle but important. The cams are different between a Mark IV and Mark VI. The oiling system is also different. The Mark VI uses a priority oiling system where the crank gets the oil first. You can tell the difference between they two by looking at the front cover. The older Mark IV engines use a 10 bolt front cover, while the newer Mark VI engines use a 6 bolt front cover.

The GM Performance parts ZZ502s use a slightly difference siemesed cylinders Mark VI blocks with aluminum heads. The Vortec 8.1 has a 4.25 inch stroke, while the 502 has a 4 inch stroke. The firing order is also different.

Andrew

Remington H.

iTrader: (2)

Well I guess I learned something new today,my mistake. That would be pretty cool then just to slap a carb and intake on a newer motor though and stick it into an old school rod. I would still want the reliability of injection though. That ta would be pretty sweet with an injected big block.

Remington

Project GatTagO

iTrader: (7)

I have a fuel injected big block in my GTO. Just click the link in my sig.

Andrew

Muffracing

Cool if you want to hook up a 28ft boat and head for the lake! A 8.1 is rated at about 340 hp and between 400 and 500 ft/lbs. And a lot heavier.

jmdale1984

iTrader: (6)

Make it easier on yourself. Get an aluminum LS series block with siamesed cylinders (from GM Performance Parts) and make a 427 or just buy the Lingenfelter LS6 (570hp Crate Motor). Either one will bolt in to your Trans Am with very little to no modification.

TieRod

I'm a little late but I know the 8.1 very well. What's interchange between 8.1 and old school BBC the water pump, exhaust, and the main caps maybe the timing cover thats about it. The pan rail is wider, taller deck 10.20, head bolt pattern has changed plus it uses two more bolt per side, coolant passages are different, and the intake ports are simile to gen III. These are just a few thinks off the top of my head.

SmokingWS6

iTrader: (1)

Intresting. Youd think it might have a higher hp output with intake runner and head designs copied from the ls1. Whats the compression and cam specs?

TieRod

For 315cc the heads don't flow that good. 9.1:1 compression I don't know what the stock cam specs are but they do respond good to cam upgrades.

busta9876

iTrader: (3)

here's the deal with the 8100, a few of ya got it right. ive swapped one of these into my 1967 chevy pickup, so i know what is different. I also scattered the motor, so i took it apart and saw the differences there.

the 8100 is a makeover of the traditional big block chevy.

the Mark IV (4) lasted untill aprox 1992 replaced by the Mark V (5)
1993 on up were Mark 5 motors, basically the only difference was updated oiling and one peice rear main seals. the main bearings recieved oil in a different fassion. Mark 5 and Mark 6 are very close to the same thing, not sure the difference between them

the Vortec 8100 is classified as a Mark VII (7)
the 8100 is a TALL deck motor, measering 10.2 inches
all bolts in the motor are METRIC threads, nothing has std threads
standard big block chevy headders WILL bolt up, using METRIC bolts
the crankshaft is a different stroke, 4.370, which is the same gm's 572
the bore remains 4.250, stock for the previous 454s


the 8100 makes 496 cuib inch with stock bore, and 4.370 stroke
the common stroked 454 to make 496, is a .060 and 4.250 bore.

the main caps are 4 bolt, they are NOT 6 bolts or cross bolted like the Gen III smallblocks
there are oil cooler lines cast into the block infront of the oil filter boss, older oil cooler adaptors went between the oil filter and block, the 8100 is different there!
the head bolt pattern IS DIFFERENT! i have looked and tried, it will not work.
the firing order was updated to 1 8 7 2 6 5 4 3, same as the Gen III small blocks, but different from traditional chevy small and big blocks.