maxf

iTrader: (6)

I would like to know what some of the advantages and disadavantages of larger displacement motors are. Let's stick strictly to SBC's; motors like a stock LS1, a forged 346, a stroker 383, a 402, or a 408.

I am considering replacing my motor with a forged LS6 based block, at 346 ci. But I have the option of going with a 383, or an iron 370. I know the iron block weighs more (roughly 50 pounds I guess), but what kind of horsepower gains would I see from more displacement?

Is it worth the extra money to go with a 383 instead of, say, a 346? (Assuming everything is identical except the stroke.) Would there be any special gains for my application, which is a Procharger?

What would any disadvantages be to greater displacement? (Aside from more weight due to an iron block vs. aluminum.)

Thanks in advance for any help. I appreciate anything I can find out

PREDATOR-Z

more cubes=more power= more torque

BTW iron block is ~92 lbs more than alum.

Difference in price between 346 and 383 is around $1000 if you use eagle crank

maxf

iTrader: (6)

Any disadvantages from going to a 346 to 383 stroker?

brad8266

iTrader: (23)

No, except that you will make a lot more power.

PREDATOR-Z

reduced gas mileage
excessive tire wear
increased traffic violations

ShevrolayZ28

iTrader: (4)

Increasing the bore or stroke effects the rod ratio, which could cause some wear concerns.

GuitsBoy

iTrader: (4)

I agree here. Also, having a larger throw will limit max rpm, or atleast increase stresses at the same RPM.

But there are plenty of pros to outweight the few cons.

Tony Mamo @ AFR

iTrader: (13)

Build the biggest engine you can afford....period....end of story.

Assuming the exact same breathing abilities (same heads, intake, cam, CR, exhaust system, etc.) the bigger engine will make more TQ down low and more peak TQ, and about the same peak power but it will happen sooner which means less RPM, less piston speed, and similar "wear" on parts due to lower RPM (versus better "rod ratio" combination at higher RPM's). Honestly rod ratio is over-rated and even the big LS1 builds still have decent numbers (in the 1.5 vicinity).

The bigger motor will simply have more average power and TQ and due to that fact will still get you down the track a little faster even though the peak HP is about the same. Other big benefit is streetability as the big engine will have much better TQ at part throttle and will idle smoother with the same cam and all things being equal.

The only two downsides are cost to build and slightly larger appetite for fuel.

The adage "there is no replacement for displacement" still hold true.....

Tony M.

oztrack

Will cruise economy be the same or any worst - since there is more low torque?? Or do the 383s lose economy everywhere?

Would someone hazard a guess at gains if i changed my car to a 383 and left everything else the same. Its done 11.414/118.6mph at 3600lb

jrp

iTrader: (16)

this is tony's motor. all things equal, only thing different is the 4" stroke.