Hit Man X

Okay I got:

9.1:1 comp stock
4.25x4.37
496 cubes.

Not too much. I am looking for:

1. Flow numbers for the heads? What kinda power levels can these be opened up to support?
2. Stock cam size?
3. Do these have TqMgt present?
4. Max overbore and Max stroke?
5. 4 or 6 bolt mains?
6. Piston material?
7. Rod material?
8. Crank material?
9. Rev to 5600rpms?

Anything else I may be missing...enlighten me please.

OOsilverado

I know they have 6 bolt mains and they have torque management. thats all I know for sure.

My guess on the bore would be 60 over, and im not sure on the stroke, im sure you could do more than 4.5". Im sure you could get it to around 530 or 540" i guess. You may want to look into the parts out there for the marine motors that are based on these engines.


You thinking about a big block now???

Jorday

If I am remembering right,

Hypereutectic pistons
Forged steel rods with 9 mm rod bolts
Cast nodular iron crank

Hit Man X

Well the DMax option is like $5K so I could in theory build a TT setup for an 8.1 for less cash or about the same. I was thinking maybe a pair of T-63s or smaller Garretts like a T-51 (remember this would be a twin setup w/ 4.05L of exhaust pushing each turbo not 8.1L pushing a single). Don't want a ton of lag...wanna be 7-9psi on 93 pump by 3500rpms but 496" has some mad torque already so it probably will not be too noticable if there was more lag induced. Probably would never run more than 14psi on 100 oct Sunoco just once so lots of boost isn't an issue for me.

The Allison tranny fully built isn't cheap... $4800 from SunCoast, but comes with multiclutch converter, 2 year warranty, and no TQ limits. Truck has that 11.5" rear end, 9.25" front diff...so I don't see anything breaking.

I'd run this N/A for a while w/ a full tune, intake, and heads/cam. That would probably make 500hp/600tq like that on the motor with ease...stock is ~340hp/450tq. So hell with just a tune and intake it could be close to 400hp.

I bet the stock cam begins to crap out around 4000rpms in the 8.1 so if I could make power to 5500rpms that'd be good. Maybe like a 240/255 .540/.570 114LSA.

Only intake that can be ported is that ASM one...also comes with an 85mm TB.

Lastly I dunno where the turbos would go. Behind the motor a la 300ZX or flipped and reversed headers being up top. Haven't got a clue about the intercooler but I think I will move the battery where the DMax's 2nd battery goes. Probably run the MAF before the turbo like my WRX or the 300ZX...if it was a blow through it'd get pegged super fast. Where the battery and stock air box go I'd probably put the intercoolers if I used air-to-water ones. If I go air-to-air maybe get some smaller front mounted I/C's like a 300ZX or TT Supra.

Factory exhaust is like dual 3" so I'd assume dual 3" would flow enough for each turbo but if not, dual 3.5" or 4" should be able to be made as the 3/4 trucks have huge caverns called engine bays that the exhaust should be able to flow around the frame.

Still a TON to think about and price out. I still haven't ruled out a DMax but a TT 8.1 would be pretty cool.

OOsilverado

Personally i like this idea better because i like big blocks.

Twin Turbos would be sweet. If I did it id turn the manifolds over and run them up front, thats how i was gonna do it on my truck, but im not sure if it would fit in the engine compartment with a big block there.

2 air-to-water intercoolers would be easier to do, or maybe just using 1 big air-to-air. These are all the same things I was thinking about when i was planning on doing mine.

Hit Man X

Yes only thing that DMax will get better fuel economy but that's not too high on my priority list when considering the 8.1 vs DMax. I picked up about 3mpg with a tune on my Z71 with a tune...so I figure that 8.1 should easily pick up a ton of power and economy with a tune. The 8.1 would pull from idle to 5600rpms vs idle to 3200rpms. hahaha

I was thinking on getting some JBA shorty's JetHot'd and flipped instead of manifolds.

Your 496 is in a K-Blazer right? That's the 1/2ton frame right?

Any ideas on how much CFM each turbo would need to flow to feed that motor? I was thinking 350-400cfm each as boost levels will be low.

Air-to-Water is more efficient but more $$$, so I don't know. Right now this is all theoritical (sp?). How would a single air-to-air be fab'd up?

Also I will have electric fans so there will be considerably more space up front too...

OOsilverado

Yeah the blazer is a 1/2 ton, I actually dont have the motor in it yet, im building it right now.

I dont know what kind of turbos to run on something like that, id have to look into it.

As far as the intercooler, you could just make your own and have dual inlets on it.

whitt1

Yes,but the Duramax with a programmer would be easier to keep in warranty,you can change it back to stock if the engine goes south at an inopportune moment[before the wrecker shows up].

Yelo

Somehow I think the warranty has run out on the K-Blazer...given that they haven't made them in at least 17 years....and OOsilverado's was made 27 years ago

Now that would be ONE HELL of an extended warranty !!!

Hit Man X

Yeah, I think two air-to-air's would be easiest to install. One where the stock air box is the other where the battery is...then have them "Y" together into the TB.

I am sure if I took a TT 8.1 to the dealer and asked for warranty work they'd a brick. But that CAN-bus programmer for the Dmax can be removed within 10min and would still have just that intake and exhaust on there if that needed warranty work.

But I'd need huge injectors like 55lbs/hr, dual fuel pumps, etc. Then those rails may not support that much power. Hell I dunno. This is what I am posting up to see what everyone else thinks.