C4VetteLS1

Ive got to throw together a combo to do some testing on the dyno...


What do you thinks going to go faster....

all forged 11.5:1 346 or 11.5:1 408 (4.030x4" stroke)..... both on a 300 rwhp shot. I was looking at Big Mikes 9.4 ET car with 700rwhp @ 3300-3400 lbs...
My car weighs 3000 race weight with driver...

There isnt going to be a 60 ft difference in the two setups from torque because a 250-300 nitrous shot off the line makes 800-900 lbs of torque and takes the difference out of the two.... The 408 weighs 95 lbs more....which is a SOLID tenth slower...

Both motors using a small valve 2.02x1.60 Absolute Speed stgx2 type head (probably not the best choice for big cubes). Which will probably limit the HP/TQ potential of the bigger cube motor making alot more power...


So what do you think, say the 646 makes 425 rwhp, and the 408 makes 675 rwhp on nitrous .....That 95 lb difference would neglegate about 20-30 rwhp of that difference..so the two cars should run pretty close within a Tenth or so ?

TTPMatt

iTrader: (18)

It depends on which way you want to go.. Yes, the nitrous off the line is a big torque monster, but of course the 408 will make more power all around. The 408 would be nice if you want to run N/A sometimes.

If you are looking at a lunati 347 or 408 kit we have 2 in stock at close to dealer cost.

Let me know if you have any questions that we can answer - 516-779-2330.

- Matt Sorian

taqwache

if you can afford it, go with the 408 iron motor. it will be alot more reliable then the 347 and make more power. with your 3000 pound race weight, i dont think you have to worry to much about that extra weight anyways.

Fast SS on TNT

iTrader: (1)

Is'nt the iron block only going to add about 110lbs or so? I too am looking at the Lunati 408 kit vs. a 348 crate motor from LS1Speed or ARE.

I would prefer to build my own motor of course. The old timer in me still prefers my own "brand" when it comes to motors.

RED01TAWS6

I'm not a big fan of adding 100lbs to the car. I say go w/ the 346 motor and spray its heart out.

Chicago Z06

I agree build it and spray the small motor.. you can spin it higher as well. not to mention if built right you can experiment with multiple stages and more HP....

Big Mike

iTrader: (4)

Build the smaller motor. As disagree with taqwache, if built right, I think the smaller motor is more reliable than the big motor any day of the week. There is less cylinder pressure in the smaller motor and you'll have less of a chance of lifting head gaskets. FWIW, I've been spraying the **** outta my 346ci. and she's still begging for more!

Vents

iTrader: (9)

there's no replacement for displacement. i feel as though there's not enough iron block guys to justify this, on top of the fact that all the 346" parts are designed to work together. i imagine we'll see 346" motors in the 8's soon. but more cubes is always a better thing.

Big Mike

iTrader: (4)

Except for when your spraying the living **** outta the smaller motor!

Reckless

iTrader: (9)

Personally, I would build the iron motor. It'll cost you 80-100 pounds, but I would just feel safer with iron. Not to mention, if you should hurt the small motor, you can't overbore it and rebuild it.

Mike, what kind of timing you running on the big shots? about 18* or so?

Big Mike

iTrader: (4)

That's a very good point!!!!!!

Todd, 15* on the 300 shot. Most likely even lower when we step it up to a 400 shot.

Reckless

iTrader: (9)

Thanks for that info Mike, one day I will be back to a nice DP setup

gator's 99TA

iTrader: (2)

400 shot! :wow: i assume a 2 stage shot?

Vents

iTrader: (9)

naah.. just all at once.

at least that's how i'd do it.

Mike, tell me that a solid roller 408 would go slower than your 346 w/ a equal shot. then i'll start building smaller motors.

now granted, there's something about the bigger ci combo's that are not adding up, and i think it's the heads. sure they're making some good power, but for the CI, it shuld be MUCH more. 427 only making 520 RWHP? granted thats alot but it's nowhere near what you could do w/ a BBC 427.

heads, it's whats for dinner.

maybe intake design, maybe some more crap, but these 422's and 434's sure as heck arent impressing me. maybe some C5R headed motors. i dunno, i figure that more of these should be running 9's n/a and 8's on spray. there's a bottleneck somewhere. be it in something mechanical or whatever, the numbers arent adding up for the faster cars.

yours mike, just happens to be one of the ones that does. good luck on 8's. you should at least get some low low 9's w/ an extra 100 hp.