I recently became the proud papa of a 200-mile LT1 block. Yes, only 200 miles, and I can still see the cross-hatch pattern in the cyclinder bores!

Reason for this thread though, is to chose a size of the stroker that will be built-up.

originally I planned for a typical 383 with 30-overbore pistons. However, seeing how the block is nearly perfect I feel almost stupid boring it out for only 6 cubes. (10 to 20 hp tops?).

I'm seriously considering a 3.750" forged crank (normal 383 design) and forged 4.000" pistons instead of 4.030's.

I plan on convering to 4-bolt mains (straight or splayed I havn't decided... need to inspect the block webbing to be satisfied), using hard-block in the bottom 1 to 2" of the water jacket, just to give the bottom a solid foundation.

I'm told the standard SBC used to go 30-over, then 60-over on the second build! :-O. Since the LT1 walls are thinner than early small blocks, I'm wondering if I should just go with the 4.000" bore and leave room for rebuilds in the future.

Will the thicker walls make any difference in durability?

With forged 5.75" rods, 4-bolt mains, and forged pistons I'm hoping to get a durable engine that can handle 500 hp NA and 700 on the bottle (direct port I imagine).

Would I be better off going for 450 hp and a larger 250 shot at the track, since 200 is really closer to a direct port set-up anyway?

Any input from those who "wish they would have" or have seen a weakness in heavy-nitrous strokers?

am I nuts?

any input on a "moderate" engine would be appreciated. This engine will NOT be getting $20000 parts or anything too exotic. I don't mind putting money where it is benifical... but to a point.

Other parts to be used:

• ported LT1 heads (early castings which had ~2 lbs more Al)
• unknown cam: no clue... still looking at general goals
• LTCC: coil on plug conversion. Not only smoother idle (which will be an issue with large injectors), but a built-in 2-step limiter, and nitrous timing retard input!
• stock PCM w/LT1_Edit (or Tunercat OBDII if it ever ships ) - 7200 rpm limit. fine for me
• Pro Magnums 1.6:1 RR (7/16", non-SA), GMPP guideplates, CompCams hardened pushrods, CompCams "R" lifters. No need for shaft rockers with a PCM limit of 7200 rpms I guess... unless the nitrous hit is a problem... anyone think 700hp will be too much for ProMags? or is rpm the only factor I really need to look at?
• I'd like to try CompCams new beehive springs as the concept seems well-founded and documented, although I havn't heard of anyone running these in LT1's yet.

to recap (it's a bit long, sorry):

a) is it nuts to build a 377? or would a 383 be worth the effort?
b) Any input on differences in hitting 700 hp with nitrous over 700 NA or blown? Is there something I should watch for? (i.e. keep rtods short, coat some surfaces? etc...)
c) any input on the products listed above. (specifically in a N20 application )

Thanks guys,
Steve

Maybe a 389ci would be better.

396 crank (3.875"), with 4" bores.

Granted, I won't be reving through the ceiling, but I could keep it to 5.7" rods and the thicker walls would help with side-loads right?

Arn't shorter rods better for high-pressure (ie. N20 or boost) combustion chambers due to the shorter dwell time?

Just a thought... and I'm tired.

if the block is that fresh,i see no reason to go .030. i like the 377 idea better then the bigger cube especially if you want to hit it hard w/nitrous. I have just never been a big fan of big cube strokers with power adders.
short rod is a good idea, lets you get a piston with plenty of crown above the ring package.

the pro magnums are fine,we have them on a 406 making over 900hp@flywheel (est).

the n/a power is gonna depend on the heads/cam/compression so you'll have to aim for 700 with the nitrous jetting once you have the engine done.

Sounds like a really cool and Fun project. like the sound of a 377 with big time nitrous and would probably make for one hell of a performer too.


Godd Luck,
-JohN

My new one is 0.010" over with a partial block fill, so as you can guess I think it's a good idea to overbore as little as possible on a power adder car.

Rich Krause

I was in the same boat. I decided to stay standard bore size with my stroker and haven't regretted the decision. Leaves me plenty of room for overbores in the future while maintaining maximum block integrity...a good thing when running power adders IMO.

You're going to have a tough time getting 5.7 rods on a 3.875. If it's possible I'm not aware of it.

I've been looking at the forged Eagle 3.875 (only for 6" H-Beam rods), JE/SRP -5cc pistons. JE/SRP only makes one piston for that combo which is the 4.030... it will not come with any other variable with the 3.875/6" match.

One guy in the club just build a 395 (approx. 440 HP / 490 ft/lbs.). His N2O is a 200 HP shot.

If you're talking about a 4-bolt main there shouldn't be any worries.

4-bolts mains have nothing to do with the strength of the cylinder walls.

If you wanted to use a 5.7" rod with a 3.875" crank you could do so. Though it probably wouldn't be worth the trouble unless you could do the machining yourself.

Rich Krause

the only problem is finding good forged pistons in the std 4" bore. took me awhile but i found probe pistons (http://www.probeindustries.com/) very nice pistons for the price. ive been spraying a 150 shot with no problems. cast crank,stock rods

JE andf the other major piston manufacturers will make you a "custom". It does cost a little more than an "off the shelf" piston, but not a huge difference.

I just ordered a set of custom "Extreme Duty" inverted dome pistons from JE. The bore and compression height are what is "custom". $720/set plus rings and pins. Total (with upgraded pins and the rings) was $870.

Rich Krause

No, the comment about the 4-Bolt Mains was made earlier in the thread. Rich, I didn't mean to confuse anyone. Thanks for clearing up the cross-communication.