drivetrain question

[beater_k20]

so i've been kicking around some ideas for either my K20, or its replacement in the drivetrain department. i've come up with a few ideas, i definitely want to stay gas powered, and i want to stay small block. the original idea that i had was a full roller 383, that should make somewhere near 460 ft/lb, and have a relatively flat torque curve. i found out yesterday that a local guy has a virgin 400 shortblock, so i plugged the extra bore size into my 383 formula, adjusted the SCR to achieve a good DCR. its low enough that with the Vortec heads i could safely run 87 octane, although i'd probably run 89 in it just for the little extra safety. what i came up with is a 406ci engine that will make nearly 500 ft/lb from 2000(lowest any of my engine programs will go) to 4000, which is where i'll be using this power. i'd like to stay auto. will a stock TH400 stand up to this kind of power? i'm also tossing around the idea of a 4L80E, as i'd like to knock down the gear ratio a little and drive the thing once in a while. will the 4L80E stand up to it?

 

[stayaway]

yep and I would go with the 400 got to CI

 

[DEMON44]

4l80e is as tough an auto as you can get in a pickup. It'll live. If ya pick up that 400..........stroke it! A buddy has a 434 SBC dyno'd at just over 500hp 500ft-lb. with 7.17's in the diffs. Stout puller I tell ya.

 

[beater_k20]

torque peak isnt nearly as flat with the 434, and it would be considerably more expensive. the other engines would be just basic rebuilds, using hypereutectic pistons, a set of used 5.7 PM rods i have laying around, the Vortec heads, and a Vortec intake. the only real expense different from a normal build would be the roller cam and correct lifters for the 400 block.

 

[DEMON44]

I understand that this wouldn't be a basic job, he's got about $12,000 into his incl. aluminum heads. I've got a copy of his dyno sheet somewhere online. I'll try to find it. I don't recall his tq curve being sharp but can't remember exactly, he built it a couple years ago now.

 

[u2slow]

The TH400 is the cheapest & strongest IMO. It will hold up as well - if not better - than a 4L80E.

I would also go to 400+ ci. Lets face it - a V8 is not going to be economical, so you might as well have all the power you want.

 

[beater_k20]

I would also go to 400+ ci. Lets face it - a V8 is not going to be economical, so you might as well have all the power you want.

economical? probably not. but why build a truck that's a gas hog just because, ah hell, its already got a V8 in it. with 450-500 ft/lb on tap, i dont think getting reasonable milage is completely out of the question. hell, it will probably do better than my existing worn out stock 350, which already gets 12mpg backed by a 350/203 and 4.10s on 31" tires.

 

[DEMON44]

I can't find it, must have gotten lost in the great interweb. I personally prefer a more stock build, but I just can't get over how that thing pulls.

But more accurate specs are
Aspiration: 850 CFM Q-Jet

Engine Mods: Small Block 400, Bored 30 over, 4 inch forged Stroker Crank, 434 cubic inch, AFR Aluminum Heads, Lunati roller cam, full roller valve train, 10.6 - 1 compression

HorsePower: 485 @ 5500 RPM 540 lbs trq @ 3500 RPM

 

[beastofablaze]

your getting 500 ft lbs just from vortechs, slightly higher compression, manifold, and a cam?

 

[beater_k20]

your getting 500 ft lbs just from vortechs, slightly higher compression, manifold, and a cam?

according to my engine programs, yes, i am. the 383 version is at 9.11:1 SCR, and the 406 version is at 8.84:1 SCR. using a Comp Cams XR258 roller cam. the flow info i have on the Vortecs is VERY close to what i have seen in real world situations on the flow bench.

 

[4X4HIGH]

If it were me i would buil a 383 and stay away from the crack prone 400 SBC. The 400 chevy blocks seem to crack quite often in the lifter valley area and pretty easily too i might add.

 

[DEMON44]

As far as the 400 blocks go, the 2 bolt main is known to be more desirable for strength than the 4 bolt main 400s. Sounds backwards I know, but the outside bolts were drilled into a weak part of the block and known to crack the webbing under high horse and high load conditions.

 

[muddybuddy]

4L80E should be able to hold up. im debating bout either a built 700r4 or a 4L80 for my next tranny, when my stock 700r4 goes, its jus a matter of time.