Ok, hopfully this is the last stroker thread for a long time

355 (3.48" stroke x 4.030 bore)
Best for high reving forced induction applications (?)

Build notes:
Forged rods (5.7" length)
Stock or stock replacment cast crank
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383 (3.75" stroke x 4.030 bore)
Best for street, all motor or forced induction

Build notes:
Forged rods (6.0" length best?)
Cast steel crank w/ 4-bolt splayed main caps
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396 (3.875" stroke x 4.040 bore)
Good all motor race-only engine, not good for FI(?)

Build notes:
Forged rods (6.0" length only choice?)
Forged crank w/ 4-bolt splayed main caps
partly filled block?
Extreme 23* heads or 18* heads??

 

Though a 355 is not really a stroker, I'll forgive you on this one

I vote 383. The 355 is definately the best budget built, and some might say the best for extreme forced induction. The 396 is cool, because it's big, and probably the most powerful, but not really worth the extra cost and concerns in my opinion.

The 383 is proven through years of abuse to be a good all around powerplant. Mass production has made them cheap and readily available. And there is no limit to the technical support you can get from qualified experts.

Just my $.02 though,

Jeremy

 

Ok, so if the rod thread is correct.. you want as close to a 2 to 1 rod ratio..
(rod length / stroke = RR)

350 = (5.7 / 3.48 = 1.65)
383 = (5.7 / 3.75 = 1.52) OR (5.85 / 3.75 = 1.56) and (6.0 / 3.75 = 1.6)
396 = (6.0 / 3.875 = 1.55)

So you would go with either stock or the 355 w/ 6" rod for ideal...

BUT.. you also should try and get close the "square" so you get both Tq and RPMs .. so then you want the 383 ...

Anyone else?

 

You just opened up a can of worms like you wouldn't believe.

You will not see a difference on the dyno between 5.7 inch rods and 6" rods on that 355. And most people who have done the proper tests agree that you will see no difference between 1.6:1 and 1.8:1 rod ratios on any of those motors.

And though I like "square motors," most of what you see in the way of hp/rpm differences are due to better airflow and more cubes.

If you take a 402 (4X4) and bore it to a 427 (4.125X4) you will make more hp and more torque.

It's just that simple.

Jeremy

 

The Rod length of course is not going to increase power, i forgot to mention that.. i ment to show how much more dependable a 355 and 383 are. The rod ratio helps lower stress on the internals and block, then less heat .. less wear.. more streetable.

"Square" also goes along the lines of the rod length, the closer to square the "less stress" a block will have to take. My point is if a good rod length or "square " block is going to seriously help streetablility .. or is it just not relevent to the LT1.. and we should focus on 4-bolt mains and forged internals?

This is just the beggining

 

Well I don't know that a "square" motor will be any more dependable than any other. Certainly an extremely over-square motor is less dependable, but moreso because it is generally run at a much higher rpm. Undersquare motors are proven to be very dependable. Just take a look at the Ferrari racing program back in the mid-50's. Enzo decided to enter some long stroke 3 liter straight-fours in with his big bore 3 liter V-12s, because they were very dependable torque monsters .

If the 396 was built in a block with another inch of deck height it would be just as reliable and probably much more desireable than the 355 or 383, but then someone would realize they can fit a 4.125 inch crank in there and bring us back to where we are now.

What i'm saying is, especially in terms of rod ratio, if you stick to off the shelf components you wont see a big difference in reliability with a street motor in any of those 3 combos.

I could be wrong, still waiting for the really knowledgeable people to chime in.

Jeremy

 

Well, i guess while we wait and see if any of the big experts come in we can play around with some other ideas.....

What about cryo treating the block for extra strength/durability?

 

How about a billet block? Or a carbon-fiber block? Or ceramic-carbon nanotube block?

Obviously some of those ideas are more outlandish then the others, but it doesn't hurt to ask why, right?

 

Whats wrong with cryo treating? There is a shop a few hours from my house that will dip my block for 350$, then he heat treats it to make it alittle soft again to make it less brittle. This is used very widely in the area for dirt-track and other racing apps.

The most common engine he dips is 350 block...

Its amazing how afraid people can be of change and new ideas

Has anyone on this forum ever had an engine cryo treated??

 

I don't have any problems with cryo treating, I didn't mean for you to think I was being sarcastic, though I can understand why you would with some of the people on this board.

I don't really know enough about cryo treating cast iron to have a good opinion on it. The only cryo treating I know anything about is with gun barrels, and the metalurgical properties are too different for most of that knowledge to apply.

Jeremy

 

No but my friend in Crossville Tnn (Mondello) has a mchine and a shaker for stress relieving all sorts of stuff.

VK did you read Jeremy's Long rod thread?

Your 355 is a 4.155 X 3.250 motor not a bad way to go

OK - Why do you guys think that you can't make enough power with a regular 30 over 350? Ok - I will agree that if all you want is a street putter than thats probably a good idea. We built a 406 SBC for my El Camino that idled at 350 RPM in gear got 22 MPG HWY made 300 BHP from 2500 to 5500 all with mostly stock parts and a Q-Bog carb.

We built many 358 EFI street Corvette engines with nearly stock parts that still run in the mid 11's and low 12's street drivable N/A @ 9 to 1 C/R One of those guys sprays his and it runs in the high 9's. and he drives it to the track.

Lets look at your idea above using the 6" rod as a baseline

9.020 deck less .020 to square it up leaves us with a 1.125 piston compression ht. That means that the top ring is .100 down or you have to use ring spacers.

It just gets worse with the 3.875 crank now the pin is up in the oil ring and you have to use buttons in it not good for the street.

What you have to understand is the low R/R creates a serious cyl head problem. Compare a BBC with a 1.53 R/R and the volume of the head used to make power - I'm talking Square ports not oval ports - but even oval ports are way bigger than any 23 head you can buy for that purpose.

Just my .02

Denny Schmidt