Diesel Place banner

1 - 20 of 20 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
I am getting ready to build up my 8.1L this coming summer. crank, rods,pistons,cam,lifters. the whole thing. I cant find a lick of info on the block or specs for the engine. this is different from the gen V motors but I cant find anything on it. i cant even find info on whether it is a 2 or 4 bolt main block. anyone help?
 

·
Registered
Joined
·
313 Posts
The 2001 truck line includes a new 8.1 liter 496 cubic inch "8100" big block. The bore will remain at 4.250", but the stroke will be increased to 4.370". The firing order is also new 1-8-7-2-6-5-4-3 and features individual ignition coils mounted near the spark plugs, similar to the LS1 Gen. III smallblocks. CR is 9.1-1 and it uses Sequential Fuel Injection (SFI). All 8.1 liter BBC production motors come with an internally balanced crank, four bolt main caps and redesigned heads with equal length port runners. The 2001 model 8.1 liter BBC uses a roller hydraulic cam and makes 340HP @ 4200 rpm and 455 ft./lbs. @ 3200 rpm.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #4
thanks guys appreciate the info. there seems to be a huge amount of info on every engine out there but the newer 8.1L I am just very power hungry I need to build this motor to take 10+ pounds of boost to satisfy me. stock I thought is was a very week engine, supercharged at 6 psi it began to come alive. hit it with 8 psi and now we are getting closer. unfortunatly I was told 8psi is all it will handle with the stock bottom end.
 

·
Registered
Joined
·
5,563 Posts
If you are lucky tierod will post in this thread since he's already done what you want to do.
 

·
Registered
Joined
·
1,964 Posts
bigblazechev1;1591968; said:
unfortunatly I was told 8psi is all it will handle with the stock bottom end.
What kind of supercharger are you using? If you're using a roots style then 10psi down low might be pushing it, but hell - if you're going to rebuild it anyway why not pulley up. :D

Use meth/h20 injection if you're afraid of cracking a piston.

Give more info!
 

·
Registered
Joined
·
588 Posts
There is no good place to go to get info, but I know allot about this engine. I will help you. First off its a gen 7 BB, with a different head bolt pattern. Its also a 10.200 tall deck, The crank is different too and a steel one may be hard to find. I would try Raylar engine or Arizona Speed. The rods are standard BB journals but much longer 6.700 long. I have eagles H-beams in mine. Raylar has Mahle pistons in stock but I found that the top ring land is a little thin. I now have custom J/E pistons. The mains caps are interchangeable with the older BB. But if you want ARP main studs, you will have to use a set for a Cummins.
If you need more info just ask.
Later
 

·
Registered
Joined
·
41 Posts
8.1

TieRod:
New to the forum, but I'm interested in what you know about the 8.1. I"ve got a 2004 2500HD with the 8.1. Seems pretty strong in the stock mode. I"ve read some where that they have the same bell housing pattern as the older big blocks, If this is true, would it be possible to stuff a 502 in its place? I realize that the intake and such would have to be changed, but not sure about the rest of it. Comments?

Thanks
Mike
 

·
Registered
Joined
·
588 Posts
Welcome to the forum.
Yes they share the bell housing, but the 502 is a slandered deck. Engine mounts are different but that can be adapted. The biggest thing would be the electronics. A aftermarket computer may be in order but getting it to get alone with the Ally may be a problem. I've considered a 572 if mine goes down again. RPM is another consideration, I've been yelled at by the diesel boys not to turn over 5,000rpm. I normally shift at 5,700rpm. I would not like to push the rpm much higher than that and a 502 or 572 will make power well beyond 6,000rpm.
 

·
Registered
Joined
·
55 Posts
For more information you might check out MerCruiser or Volvo Penta's websites. They both marinize 496 engines.

Two marine versions: 375hp which has a more aggressive camshaft than the truck 8.1L and the 420/425hp version which has an even more aggressive cam, different pushrods, and a forged crankshaft. With CMI headers, you can get a 425hp 496HO MerCruiser to make over 480hp @ 5000rpm changing nothing else (torque over 550lbft in the mid-range).

Like someone mentioned above, check out Arizona Speed & Marine. I saw in a Powerboat or HotBoat magazine recently that they built an 850hp supercharged 496 (forged everything). It was obviously built for a boat, but a lot of the same principles could be applied.
 

·
Registered
Joined
·
1,796 Posts
The diesel boys are jealous cause they can't turn 5000. 572/720 can turn 7100... :grd:
 

·
Registered
Joined
·
1,016 Posts
They're worried about the stock torque convertor balloning above that speed. The engine is Chevrolet based, RPM capability isn't laking.

Vernon
 

·
Registered
Joined
·
5,563 Posts
Actually some of the crazy pulling guys have run them to 5000... Awful loud at that rpm I imagine, I haven't had mine above 3800 and it's starting to get loud there.
 

·
Registered
Joined
·
588 Posts
I've turn my 8.1l 6200rpm a few time by accident. :(
 

·
Registered
Joined
·
575 Posts
Stock,it seems a waste to rev it past 4200 or so.It just makes noise,and signs off.
 

·
Registered
Joined
·
273 Posts
My 454 has a redline of 4000 rpms. I like it that way, it's all torque, doesn't rev hard, engine lasts forever. I'm not a fan of revs. Prefer displacement. :)

As to the issue of the 8.1... 8 psi I would imagine to be the limit not because of power reasons, but rather because of detonation reasons. If you aren't running an intercooler, then this might be your problem. If you add an intercooler, you will probably be able to run 10-12 psi without problem.

Keep in mind, you are shortening your engine's life no matter what you do, because you're raising the cylinder temperatures and pressures. This kills your engine faster. If you are ok with building up the engine, then that's less of an issue, but I would try to milk this for as much streetable horsepower as you can.

Knowing what kind of blower you're running would help as well. A Kenne Bell/Whipple/Lysholm supercharger (twin-screw) is going to allow you to run the most boost and make the most power because they by far have the best adiabatic efficiency. They also are significantly tougher to plumb an intercooler in with since they sit on top of the engine. The centrifugal units (Paxton, Vortech, ProCharger) produce more heat (lower adiabatic efficiency), and you will be benefitted significantly by adding an intercooler. Roots blowers (Whipple, and most factory applications) are by far the worst in terms of efficiency. For example, on the supercharged Mustang Cobras, just swapping the factory Eaton M112 (roots) for a Kenne Bell (twin-screw) makes a significant power gain with the same boost, plus you can then add more boost because of the improved efficiency!

Let us know more about your setup. Pics would be really nice! :)
 

·
Registered
Joined
·
2 Posts
The 8.1L heads are junk for making power out of, if you are serious about building this motor you should look at the only performance heads available for them - developed by Darin Morgan of Reher-Morrison Racing Engines. That's why the 375-480hp numbers being thrown around are horrible, a 500 inch motor should easily make 600hp, the heads choke it.

http://www.raylarengine.com/cylinder_head.html
 

·
Registered
Joined
·
588 Posts
MachinistOne;1624899; said:
The 8.1L heads are junk for making power out of, if you are serious about building this motor you should look at the only performance heads available for them - developed by Darin Morgan of Reher-Morrison Racing Engines. That's why the 375-480hp numbers being thrown around are horrible, a 500 inch motor should easily make 600hp, the heads choke it.

http://www.raylarengine.com/cylinder_head.html
Yep, thats what I have. With a turbo to boot!
 

·
Registered
Joined
·
588 Posts
I'll get some pics tomorrow. I'm still getting everything set up.
 
1 - 20 of 20 Posts
Top