Basically, the same engine, same heads, same everything
except one will be a 383 and one will be a 346.

How much difference will there be in performance.
If we are talking 10 or 20 more HP the 346 is probably better.
If we are talking 100 more ft of torque then the 383 is better.

I am not a 1/4 mile guy. I do autocross.
So, I want the engine to hold up to 30 minutes sessions.

The 383 will hold up, but maybe not as long.

The price difference is like $1200.

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GM L33 Blueprinted core block
King racing rod bearings HP
king racing main bearings HP
TMS single piece racing cam bearings
TMS forged crankshaft
TMS 4340 forged H-beam connecting rods with ARP rod bolts
Diamond racing pistons
317 heads
Stage two blower cam
Votech Super Charger

Do you guys like the 317 heads? I was told they are better then the 853's
I have for my use. They will lower the compression and make the
engine run cooler, plus flow a lot better.

 

I picked up a 383 kit for a good price! King xp racing rod and main bearings are included with the kit, and a Aries moly ring kit includes -3cc flat top 11:1 comp with 66cc head!

http://www.cnc-motorsports.com/clear...mpression.html

 

 

I'm 99% sure Thompson MotorSports will be building my block.
I have been watching him in the forums for about a year.
Seems like a great company.

I'm not looking to for the cheapest route.

But that is a great price!!!

 

Well I assumed everyone liked to save some money lol and eagle is a very reputable brand along with Aries they've been around for a very long time! But good luck on your build, personally going with a built short block I would be opting for better heads than factory.... 853 heads suck...317s do flow very well for a stock casting

 

the 383 short block would like better flowing heads ,and a cam with the proper valve timing events to deal with a longer crank stroke .

 

A four inch crank would live in an LS3 block with slightly longer sleeves (for more piston support at BDC) and a dry sump oiling system to aid lubrication for the half hour track sessions. Since you're running a supercharger, I'd stay 346, forged rotating assembly, with the 317s and flat tops. IMO the shorter stroke will drive better through the turns when applying the loud pedal, especially with the torque production from the air ramming device.

 

It's 37 c.i. or so expect a minimum of 37 HP difference with the correct combination. The torque number will be much closer to the HP number with the stroker. Build for torque, tune for HP.

 

It'll be worth more than 37 horses....
figure at least 1.4 per cube would be more realistic..

 

I was always told that if everything is exactly the same there will be virtually no gain in hp from the larger cubes. Broader tq curve yes but that's about it

 

The first mistake you're making is using the same exact everything for 2 completely different builds. Thus, you may not see much of a gain going to a 4" stroke simply because you will have a mismatched combo that was meant for a stock stroke.

Build the top end/valvetrain around the different displacement values and yes you can see good gains of 40-50 accross the board. Leave the same stuff in and you won't.

So it's really up to you on this answer, not the engine.

However I will say this, for that type of driving the 383 will offer you a broader torque curve giving you better acceleration power out of the corners and a more responsive car for tip-in power.

As a drag setup it won't be much difference since you spend most of the time at 5000+ rpm and both can be made to make similar power. A stroker however gains you power all over the range, which as a autox/roadcourse driver you get to use that power more often than a drag racer.

 

That's true about the torque curve. Stroker motors are known to peak power before a motor that's not a stroker. As far as horsepower goes I disagree. Let's think about that..... let's take a 408ci most common LS stroker motor ever~ most guys running them with great heads such as afr,tfs,mast,etc..... is north of 500 rwhp. Not that many 500 plus rwhp horsepower 364ci on the scene here.

Well anyway figure I'll share a 383 build.... http://www.truckinweb.com/tech/1208tr_5_3l_bow_tie_builds_mild_to_wild/

 

You make a solid point for sure. It's only what I've heard a few times...and from good sources, but I can't say for sure from my own experience.

 

The compression loss is not worth the flow gains. Compression is your friend for TQ and making more power streetable and keeping power in the whole range.

A little bit of work on your ls1 heads or some 243/799 heads are a much better choice.

 

I don't have the money for the engine. I was planning on it lasting another year.
So its get a rock solid bottom end and budgets heads.
Then if I need to later on I will upgrade the heads.

The 317 are large cc thus they will lower my compression and overall reduce heat.
Cam will be picked by the engine builder, and verified on this forum after I decide
on the best cam. I said same everything because I am not replacing any of the stuff I have.

From what I have been told. On a blown motor compression is not your friend.
It just makes heat. It does not make more power.

Engine builder has a set of ready to go 317 he will sell and install for $500.
So that is a budget upgrade over my 853's

I think the torque is worth it.
I can find a way to keep the engine cool.

 

If your engine is running hot during an autox run there is a problem. Flush the coolant, lower fan settings in the tune, and open the hood between runs. It shouldn't see over normal operating temp anyway though. LS engines like to run warm.

The 317 heads are not really an upgrade. Boost guys use them for their flow and lowering compression on a stock bottom end turbo/blower build. That's what they are good for. They will do nothing good for a naturally aspirated 346 or 383 unless they are milled a ton to gain compression back.

317s will cost you tq and under the curve power (which are 2 of the things you will want most for a serious autox build)

 

Have you ever been around a blown vette?
I have not met a single blown vette that could keep it cool on stock
parts for 30 minutes.

I know several guys. Heat is the single biggest issue on autocross.
Every blown guy knows it.

If your not getting to 310 degree engine temps in 20 minutes your not pushing that car.

My coolant is flushed before every race.
My radiator is spotless. I take it apart and clean it every few races.

10lbs of boost just boils oil.
Drop below 3000 rpms for a lap and it cools down nicely.

 

Did you miss that I am blown. Vortch V2, 3.4pulley 10lbs of boost

 

Doh. Yes I did.

No more posting for me prior to morning coffee. My apologies haha

 

All good.... I posted the first one to fast as well...