Ok this is not an update for my build, it is a question for general readers and for my own knowledge. Please make your explanations understandable for newbies. The question is what is the difference between a LT1 383 stroker and a regular 350 LT1? Also what is the difference in horsepower on average. I am asking because someone said that they are the same thing and there is not too much of a difference, and although I am new to this, I don't agree with that. Someone please explain this.

One more question. What is the average price for a machine shop to bore the engine and port the engine?

Thanks

 

I'm too lazy right now to type up the differences, but if you do a Search you shall find all the answers to your questions

 

lt1 350... 3.480 stroke crank, 5.7 rods, pistons for 5.7rods <-this is stock setup
lt1 350.....3.480 stroke crank, 6.0 rods, pistons for 6.0 rods
lt1 383.....3.750 stroke crank, 6.0 rods ,pistons for 6.0 rods
lt1 383.....3.750 stroke crank, 5.7 rods ,pistons for 5.7rods


hp and torque will differ from different combinations of internal parts.. safe to say at least 40hp/40tq difference, probably more than that actually..

i never really cared for 383's myself, i know they are a solid setup, but i've always preferred 355's for some reason... i guess mainly back in the day you had to clear the block and rods manually, and i didnt care to manually grind on a block and rodbolts to build an engine.. guess it was laziness...

 

Just adding a few cubes of displacement probably won't even be very noticable. The power gains come from using new heads, higher compression ratio, new camshaft, overall higher airflow through the motor, etc.

 

True, but to a point. You can get 550 rwhp from a 396 at a lower rpm than you could with just a 350. Plus the increased displacement brings a higher and broader torque curve. This is why aftermarket LSx engine blocks have enthusiasts like us salivating. Up to 515 cubic inches! The most out of an LT1 block was 421 ci (not including the rare GM performance LT1 that "supposedly" you can go to 434 ci, but these are like 4 valve Areo heads. They exist, but you never see them in real life...)

Sorry, I hijacked your thread. My bad.

 

The rod length doesn't matter. Just confussing the issue. To be a 383ci. you need a .030 overbore also.
Basically a 383ci. is any combination that gets you 383 cubin inches. The usual way of doing this with an LT1 is to install a 3.750 stroke crank and bore the cylinders to 4.030.

 

those are the most common combinations to build a 383, and the rod length is important..

staying naturally aspirated most would choose the 6.0 rods to cut down the rod to stroke ratio to improve the life of the cylinder bores, and it frees up a little hp and torque..

if someone was using nitrous, they would take into consideration of using a shorter 5.7 rod for more strength for the nitrous.

 

Or a 5.85" rod......... Works very well in a 381 (4.020" bore x 3.75" stroke) with a 300-shot.

There were some good discussion in the past on the Advanced Tech forum, regarding the importance of rod length/stroke ratio, and the consensus was that for the kind of engines we're building - street or strip - its not really very important.

 

Weight of the reciprocating components make a huge difference as well. Lighter = longevity.

 

Now your talking use, not components. The only things that have to change are the crank and pistons. Period.
And please! The stroke/rod ratio in a small block! I'll bet you can't measure the hp/tq difference.

 

hp is made through the heads weather it's a 383 or 350. The torque curve can be tweaked with the cam..............However the torque created from a 383 is a LOT more than that of a 350. A 383 is much better, in my opinion, on these larger head/cam packages for street as you don't lose all that down low torque to make the same hp a 350 would make by reving to the moon.

Case and point. My brother and I have the same head work on our cars. He has a cam that is similar to mine. His is a 350 and mine is a 383. His car doesn't come in the power curve or feel like it is getting any real power to it until 4500 rpm and above(not that street friendly). Mine however has instant throttle response by 2000 rpm and makes about 40 more hp due to the NA cam compared to his nitrous came at about 1000 rpm lower in the rpm band. Thus my reasoning for the 383 being a better street/stip animal with more room to grow and make more power under 7000 rpm. Mine peaked at 5900ish rpm and managed 91mph in the 1/8th mi.

My buddy who had a valve job and GM847 cam on a 350 I believe managed 88-89mph in the 1/8mi reving that sucker up to 6800ish rpm.

Hope this helped in explaining some of the differences as far as performance from someone who has driven all 3 mentioned vehicles in this post.

 

i cant measure it, but i bet a decent dyno can..

 

10% more displacement is still 10% more displacement, with no more weight. .Seems like a good idea to me, why stop there though and go for a 391 with a little more boring! ^_^

 

And I'll bet it CAN'T!

Rod Length Relationships: Bill Clemmons, Jere Stahl

III. NOTES

A. Rod Length Changes -- Appears a length change of 2-1/2% is necessary to perceive a change was made. For R & D purposes it appears a 5% change should be made. Perhaps any change should be 2 to 3%--ie. Ignition timing, header tube area, pipe length, cam shaft valve event area, cyl head flow change, etc.

Not from above article.
Before you go out and buy longer rods, let me just say that the gains are very small. This debate has been argued for years and will not end anytime soon. In my opinion, if are building an engine and need new rods and pistons, a longer rod will cost about the same. That makes the small benefits worth it. I would not waste my money buying longer rods if you have a good set of rods that you can use. Use that money to make more power elsewhere in the engine.

 

There is a benefit from a long rod setup, however it does not apply to 99.999% of LT1 builds. IF you are building a VERY high rev setup the issue of piston weight might be significant. A long rod/piston combo has lower piston+small end weight.

Example (SBC Compstar rods and JE flat tops). Note the I am approximating the reciprocating weight with 1/2 the rod weight. When actually balancing the rod big and small end weights are measured.

5.7 rod: rod=603g, piston=439g, reciprocating weight = 741g
6.0 rod: rod=612g, piston=413g, reciprocating weight = 719g

Now, a 22g bob weight difference is going to be meaningless for nearly all builds. However, if you were building a max effort high rpm engine, the lower stress imposed by the decrease in reciprocating weight could be significant. Also, the difference in overall rotating weight of 176g (8x22) might allow the engine to rev marginally faster.

I offer this just for informational/discussion purposes. We are talking VERY small differences but they do illustrate something about how engines make power.

Rich