TS6

iTrader: (41)

Still trying to figure out why you think I would have to spin a 408 more than a 346? RPM is RPM, regardless. Doesn't make sense.

JASON11WS6

iTrader: (7)

I think he's just saying that stroker motors have more rotating mass due to the longer stroke. I don't think that is a real issue here or even on most LS1 strokers. Unless you are going with a stroke of over 4'' but not to many people do that.

mikep2002

iTrader: (10)

I love this stuff as I am also facing this question as to 346/383.

ty_ty13

iTrader: (42)

i would rather have a 370 than a 383... because you have a bigge bore so you have have a bigger head and will flow better....

TNTramair

iTrader: (15)

I understand not needing the extra cubes to make big power but heres what i think about and ive asked the same question and most people agree....

in theory, a supercharger wont need to work as hard to produce the same amount of power on a 402 as it would on a 346ci. therefore putting less stress on the internals of the motor???

346 w/D1-SC@12psi on pump gas will produce what...560-590hp??
402 w/D1-SC may only need 9-10psi to produce the same amount of power. also takin into consideration that both motors are forged and have equal bolts ons...(injectors, fuel pump, intake, etc etc)

am i wrong?? someone educate me if i am lookin at it the wrong way. cause i just purchased a forged 402 for my current project which i plan on running a D1 on...looking for 650rwhp.

QSPres

iTrader: (15)

Huh? A supercharger doesn't know what its on. It will blow a certain amount of air per revolution. If all that air makes it into the combustion chamber before ignition, it burns. If a 402 has a bigger bore than a 346, and the supercharger can supply the additional air to fill that space, it will make more power. If it can't than it won't.

PSI means nothing for this discussion. Its all about VE, volumetric efficiency. A properly sized blower on a 346 will make far more power than the same sized blower on a 402. Why? Because it can't supply enough air to bring the VE of the 402 up!


The 402 has a heavier rotating assembly, which places more stress on the main caps, rods, bolts, and pistons. The faster you spin it, the more stress is applied. The 346 has the opposite problem, in that it stresses itself less, but must rev faster to produce the same power (pump as much air). So you get wear on things like valve springs, bearings, rings and cylinder walls.



For a street car, it almost doesn't matter, but if you're planning on racing, its a delicate balancing act.

QSPres

iTrader: (15)

Never said you'd have to spin it more.



It's just more wear on the bottom end because of the weight.


RPM isn't RPM sometimes. Reason why a nitrous motor is less durable than a turbo....

ZDOG

iTrader: (13)

well now that my brain is a liquid past like ooz...is a 383 easier to tune than a 400+ ci? how does a zo6 cam behave in a 383 or is there better options? also is the 383 on the ragged edge for the block or could it still take a cleaning and rebuilding? im looking for north of 700 rwhp. i just had the install done of the d-1sc and although 470 rwhp is fun.... like you all have said it leaves you hungry for more. im looking at larger ci mostly for a little more down low torque. as i drive now on cheap 315's (ten bolt) at the top of first the tires break free, second gear is useless and either third graps, the clutch goes up in smoke, or the pedal sticks to the floor.(stock clutch, i got a twin disk to go in, in the spring). im looking for a earlier torque hit so when i order the 9" and get some stickies it takes off like a raped ape with out gearing it lower than 3.42's. id be happy with a forged 346 if i could get my goals out of it. keep the thoughts coming. im currently looking at texas speed and spdc's shortblocks. thanks

TS6

iTrader: (41)

[QUOTE=QSPres]

PSI means nothing for this discussion. Its all about VE, volumetric efficiency. A properly sized blower on a 346 will make far more power than the same sized blower on a 402. Why? Because it can't supply enough air to bring the VE of the 402 up!


QUOTE]


Care to rethink that?

Do you actually have any experience with this stuff?

QSPres

iTrader: (15)

Tom Byrne of Tbyrne Motorsports

Pat Burke of Ocean State Performance


Jason Enos


Manny Buginga



Just a few of my friends. Wanna ask again?

The Red WS.6

iTrader: (4)

I thought boost was a measure of back pressure which is why hondas and teminators have bigg boost readings as the VE is inefficient? The lsx flows better, is bigger and registers lower boost with bigger (or the same) hp numbers with (the same) less boost?

WhiteKnight98TA

iTrader: (1)

do both!!! no matter what I don't think you'll be dissapointed though. Good luck with everything!

EPP

iTrader: (22)

All of these engine cubic inches are basically the same to tune, we don't see any of the LS engines being any different.

The 383 is just the same bore as the 346, but with a longer stroke, you would use a 4.0 stroke on the crank to make a 382/383. Put a 4.0 stoke in a 6.0 LS2 block and you would have a 402.

Your 346 block turned into a 383 is a great combination, you will need a new fuel system to accomodate it, and expect 700+ rwhp. Bob

ty_ty13

iTrader: (42)

hp is based off a flow of air and fuel... it doesnt matter if its a 502 with a d1sc on it or a 346.... the one that flows more air will make more power.... and a 502 will make more power off idle with a centri than a 346 will because it makes more NA.... your theory of a 346 will make more hp with a d1 than a 408 with a d1 is wishful thinking...

kp

iTrader: (34)

You are limited by the amount of air the blower can make, while a more effiecient setup (CID, heads/cam) will make slightly more/less power with that same amount of air it all depends on what you want to do.

I think a 346/D1SC is a pretty good combination but what do I know. I honestly dont think I would run any better with a 370/402 or whatever if that was the only change I made unless I stepped up the size of the blower.

ty_ty13

iTrader: (42)

i think since you are a a4 car your gains would not be significant.... because it keeps your rpms up so the lower rpms are not used.... but if you were a stick car with 3.5 gears id say youd see again because of the more torqued you'd have below 4.5k rpms

but yes, its not going to affect PEAK cfm because the blower will only push so much... but a bigger motor i think will effect how soon it sees that peak cfm....

this is only theory because i have never swapped out motor combos on the exact same blower...

but id also say you might also see a slight decrease in IAT's

TS6

iTrader: (41)

And? No offense, but I have friends who are good at **** too. I have a friend thats going to be building a Studebaker truck for Boyd Coddington (Boyd isn't anywhere near as talented as this guy). I can't paint a ******* barn red, so what is your point? I didn't ask if your friends have any experience, I asked if you did.

I'll bet you anything if you pulled my motor (408) and put in a built 346 and left everything the same it would make less power. I would love to hear some real reasons why you think a 346 would make more power. Boost is a function of backpressure. Bigger motors flow more air and allow more of the blowers air to make it through the engine therefor making more power.

lmt0705

iTrader: (7)

hey Bob, can you chime in on this conversation, I know you build and dyno all different kinds of procharger motors and I figure you would have some good input will real numbers to share for us

JASON11WS6

iTrader: (7)

No one said they would make more power with a 346 comparied to a bigger motor here. All we are saying is that your not going to make a bunch more power. The blower has limits, a 402 will definately make more power NA then a 346. But lets face it, with a blower they are well past their normal power limits of NA and are depending on boost. Once the blower maxes out your not making any more power. Like KP said a 370 would make more sense then a 383 mainly because the bigger bore. You could run LS2 heads which will flows better do to the bigger bore. Oh, and a LS6 cam would be pretty small on a stroker motor but have seen a couple people pull good number on a 346.

mikep2002

iTrader: (10)

Easy there, lets keep this as good information and knowledgeable opions not a big pecker war.

Good idea I would like to hear from BOB.