stock48

iTrader: (17)

Got you mixed up with 99SLEEPER, sorry it was late last night. I also agree with the stock crank 370 being a good choice for turbo, but for what he is doing I think the 408 with the forged crank would be a good choice.

ninetres

iTrader: (35)

Sooooooooooooooo again, why is the forged crank a good idea for what he is doing? You still didn't provide me your reasoning. I'm not tryin' to bust your *****, just curious. Why 408 over a 370, even if both cranks are forged?

stock48

iTrader: (17)

Blowers/ superchargers place alot more load on the crankshaft than turbos, especialy the snout, and the snout is the smallest part of the crank, with a large hole drilled through it. If you are making 600HP with a turbo your crank is seeing the stress of 600hp. Same engine making 600hp with a supercharger might be making 700HP, and taking 100HP to spin the charger, all off that small snout with a hole drilled through it. This is just my opinion, and how I see it. Your view might be different, and that's fine as long as it works for you

ninetres

iTrader: (35)

Ahhhhh. I see. Makes sense. I'm thinking a 370 (with a forged crank) would be the best bet then. I just forsee the D1 running out of steam in upper RPMS in a big cube motor. But then again, the 408 leaves room for blower upgrades

stock48

iTrader: (17)

Yes it might run out of steam at bigger power levels, but for 550HP it should be able to keep up.

ninetres

iTrader: (35)

It should make 550 at 1psi lol


^^^SLIGHT exaggeration

TS6

iTrader: (41)

Why spend the $$$ on a forged crank and not gain the extra cubes for free?

There are quite a few of us making good power with a 408/D1 combo. I still have alot of room left on mine and I'm making 740 at the tires through an A4, big MT's, and on pump gas.

nvmy2000ss

iTrader: (17)

I would really like to know your setup. I am in the process of building a 408 and there are so many posts that say the little D1 wont be enough and will run out of steem its begining to worry me, but it seems you have done just fine. I really hope my setup will produce good numbers like yours. Really I am just looking for the same power as my little 347 (man I loved that motor, 620 at 14psi) just on lower boost and a bit more torque
Sorry to jack the thread.

macleod

iTrader: (2)

I have a 408 with a very mild cam, D1 at 11 psi makes 635 rwhp/571 rwtq. Pump gas and the stock dual intercoolers. Once I get a front mount we can turn up the boost but hell I can't get the dam thing to hook now on the street so not sure the point to turning it up yet

ninetres

iTrader: (35)

I was under the impression that on high boost, and any decent rpm, the D1 could not keep up with the air requirements of a 408. No?

bad6as

iTrader: (17)

as fas as cost goes, mabye a forged 347 with some afr heads and maxing out a d1. 700-800 wrhp

tomz28

iTrader: (20)

my 346 at 11 psi is a tire killer even with et streets i dont see how you guys get these cars to hook. im changing my suspension around to make it work with the tires

TS6

iTrader: (41)

408 with Dart heads, secret-ish cam, D1SC, FMIC, stock ecm, LT's, etc. Right now its on a 3.85 pulley making 13 psi at around 6500. I could drop to a 3.4 pulley and make maybe another 100 RWHP.

That being said, it could be done on a 360 or 347 with the D1. The reasons I went 408 were:

Bigger= always better.
Potential: bigger cubes has the potential for more power
More torque down low and off boost to move my heavy street car
Durability of the iron block
Wanted forged crank anyway, extra stroke is free.
I can slap a F1x blower on here and be ready to make massive power.
I also sold my H/C stock longblock for $3K, which made the 408 cheaper than rebuilding my motor.

The blower will support "X" amount of power. In most cases the compressor size is what determines power output. Since everyone starts out saying "I only want xxx HP then needs more later, I decided switching head units in 20 minutes was better than building another motor.

mikes99corvette

iTrader: (5)

Im currently building a 408 Iron Block with Patriot LQ9 Stage 3 Heads (73cc.) and will be using ECS Big Blower Cam for my D1SC! ! The cam is in the 23X/24X and 115 range. The D1SC pulley will be a 3.7 but will also be using an 8" Crank pulley! ! Im hoping to be around 750-800 on an A4! ! Its going into a Corvette

Turbo LS1 SS

iTrader: (7)

ill retort since ive had my 408 s88 car running for a while now. a lot, LOT of power. low boost. no issues at all

REGALIS

You would save yourself alot of money using the parts you have. Instead of buying a fancy short block, personally I would use the LS1 shortblock and invest in heads/cam and intake. Depending on what power you want to make, the stock LS1 shortblock will handle easily 500 rwhp all day and be reliable. 364 and 408 are good options if you are planning on making big power but un-necessary for a mildly boosted street engine. IMHO