Ok, just discovered a couple of new vent holes in my oil pan today. So, there goes the stock rotating assembly, at the minimum. I can feel the parts through the hole just laying in there. Just to give myself an idea of what I can do, I thought I would post this. I'm tearing the motor apart this weekend, but I want to start planning out my possibilities.

I am thinking a 383 kit for economical/power purposes(Versus a 396 or 355). My questions are:

1.) Do I have to use an internally balanced setup on my '93 LT1 6spd?
All the kits out there seem to come with flexplates instead of flywheels.
2.) If not, can the dual-mass flywheel still be used along with the LT1 hub on a 383 rotating assembly?
3.) If I have to use internally balanced, can a regular old externally balanced 383 kit be made internally balanced for a reasonable cost for use with the stock hub and flywheel?


:cry :cry :cry

 

1. no
2.yes - but you will still need to balance the assembly
3.yes - but the goes up quickly the more heavy metal they need to add to balance the assembly

 

Ok, cool. Now about parts selection.

I have been looking at using a nodular iron crank. These can handle the 450hp max I am looking for. Probably the SCAT 9000 series. 3.75 stroke

For rods, I have the 5.7" SCAT forged I-beams laying around the garage that I can use.

For pistons, I will probably go with hypereutic to save weight. Especially since this will be a N/A motor.

Also, are Moly rings still the rings to use. I haven't looked a building a motor in years. I know they require the different honing.

Does this sound good for a 450hp @ flywheel motor?

What is your opinions of knife-edging the crank. I know this is suppose to be better for performance, but is it a good idea for a street motor?

 

ok, lets see..

I jsut finished building my 383... I used the scat 9000 crank.. and was very happy with it.. I also used the stock flexplate and balancer.. It required heavy metal.. I used the stock rods and had them de-burred.. and I used Kieth Black Hyperutectic pistons with moly rings.. love'em.. however, the machine work is critical with KB pistons.. make sure the machine shop follows the directions for machining the bores that come with the pistons.. making 450 flywheel HP depends on how much porting is done to the heads, the camshaft you select and the intake and exhaust system spec's.. LT's will be required.. I went with a mild cam and kept the stock exhaust.. I'm probably only making 350fwhp.. but i think 450 is possible..

 

you guys drive me crazy you talk about good rods and good cranks then top it off with hyper junk and i am sorry to step on anybodys toes who used them in the past but if you are going to good stuf in the motor then put forged pistons innnnnnnnnn!!!!!!!!!!!!!!!!!!!!!!
that is what going to break first the pistons not the crank not the rods the pistons did you here me yet it is just cheap insurance
i know i will hear from some of you say stuff like i have them and havent had a problem but believe me they are just tiny very tiny step better than cast
glad i got that off of my chest :D :cheers:

 

nuff said :smash:

 

Actually, they ARE cast. The term, hypereutectic, only refers to the supersaturated silicon content of the alloy used to make the piston. The pistons are not forged or made by some mystrical, "hyper" process. They are made by casting them.

RACE ON!!!

 

cfi-efi i know this you know this
lets not confuse these guys anymore than we have to :cheers:

 

Yes, yes, yes. Silicon for hyper and hypo. But they weigh tremendously less than forged equipment. I know what you are saying, I think. Does switching over to a forged setup make the motor sag like an 80 yr old woman? This has always been my view on the subject, but this could be another one of my many mistaken beliefs. I can afford forged pistons, I just figured I would save some rotating mass by going with the hypereutic for a nonblown motor.

By the way, the extra 12-16% of Silicon DOES increase the strength of the castings, trremendously, just not to forging levels. Heck, they lasted 100,000 miles of street racing style driving from me. Well, 40,000 from me, the rest from the previous owner.

 

Whats with this? Oh, please don't confuse us. Did someone ever mention that hypereutic pistons were not cast? I think it was just mentioned as an imporvement over cast pistons. And when you look at "cast pistons" in the average catalog, they are not of hypo/hyper design.

If you have something to share about stroking(engines), please share, I swear we'll try our best to avoid serious confusion.
:)

 

hypers have a stronger tensile strength than forged.. but are brittle.. when they go.. they shatter.. which usually takes other components with them.. whereas forged pistons are more ductile.. and when problems occur they tend to warp/deform thus usually saving the rods, heads and block.. you will be fine with hypers as long as you dont aggressively spray or run lots of boost (over 8psi I think). LT1's come from the factory with hyperutetic pistons.


[Modified by BluByU, 1:47 PM 8/20/2003]

 

OK, cool. Next and last preliminary question. I know I threw a rod and I smell antifreeze coming from the oil pan, so my block is probably cracked. Hopefully it is just a blown head gasket.

So, about blocks. My best bet is proably a junk yard on affordability. What about the f-body LT1 blocks. I know they are only two bolt mains, but that can easily be modded for splayed caps, which are better anyways.

But what about the other differences. I wouldn't imagine the single knock sensor would be a problem. Are there any other differences which I would require further modification? Or is there a good place on the internet to get a block. I don't need a race-prepped deal, just a good core.

 

I was looking into cores for my LT1... the prices were all about 1000.00 for a running LT1....

 

good question.. i would take your out first and inspect the damage before i spent to much time looking for cores.. the blocks are pretty tough.

 

I COULDN'T AGREE MORE

I did a 355 rebuild on my 89 and was gung ho about hypers. 25K miles later:
There is a big crack on the other side too.

Am running an all forged 391 assembly now


[Modified by 89 Paul in Cal, 1:11 PM 8/20/2003]

 

ouch.. what was the cause of that?!? :eek: did you juice it? forced induction? 6000rpm? or did they just let go?

 

Ill have to go along with the guys that say to get a good set of FORGED PISTONS, I ran HYPEREUTECTIC pistons for TWO YEARS in a 383 with mild (100hp) NITROUS with out problems but EVENTUALLY my pistons looked EXACTLY LIKE PAULS, HEYPER pistons WILL eventually fail (AND FAIL FAR FASTER THAN FORGED PISTONS TOO!) if your running the engine hard and for any reason get the engine into detonation, now IM NOT saying FORGED PISTONS ARE BULLET PROOF, ONLY THAT FORGED PISTONS TEND TO HOLD UP TO ABUSE MUCH LONGER!

 

Two places you don't want to skimp on: Pistons and machine work. Both are the core foundation of your motor. You can use stock rebuilt rods and a cast crank and make an ungodly amount of power with them (witness some NHRA Stock Eliminators and/or Limited dirt track) but your pistons take a severe pounding. Hypers have higher tensile strength than forged? Ok, you can't pull them apart but that's not the stress imparted on a piston, that's the stress imparted on connecting rods. Pistons get the shemp hammered out of them by the pyrotechnics inside an engine. Use forged...

As for your block if you have parts in the pan the most likely you shattered a piston which sent the wrist pin on the now "free" con rod through the cylinder wall at which point you snapped the rod or blew the rod cap off and through the pan...I would almost bet that's what happened (cuz I've seen that too many times) and will go on and say that your block is probably junk.

Now, on to components... You need to determine what your power goal, budget, and any future plans may call for in an engine. Maybe you've toyed with the idea of running some bottled aggression or a blower at some point; need to know that before the build. Need to know what your REALISTIC power goals are. And finally, and usually most important (though I do love those customers who say "money's not an object"), what is your budget? Typically you'll need to add 10-15% to what you have figured. Once all this has been determined then start selecting components. For the cost of some of the lower priced forgings nowadays I wouldn't build a cast crank/stock rod motor. Eagle and CAT both build excellent 4340 forged cranks and rods for NOTHING! While I'm a Callies man in general I've never hesitated to build a motor with these pieces; I've only had one Eagle crank that didn't check out dead nuts on and never had a CAT that didn't. True, they're not Callies or Cola, or BRE; but they are good cranks for little money and are a monster amount better than a cast.

Pistons, as above, go forged. Most of the 2018 performance forgings offered by JE, Ross, Wiseco, and even TRW are LIGHT...Much lighter than their 4032 forged counterparts. Most of these companies also stock a shelf piston perfect for your application so you don't have to spend a lot of money. As for balance, if you choose a crankshaft with the proper counterweights and match the other reciprocating components so you don't have a bobweight that is "way" off; you'll rarely need mallory for internal balance (which is what I would suggest). The only time I HAVE to use mallory is when you have a really heavy bobweight.

Steps to building a great engine:
1) Plan
2) Ask questions
3) Plan
4) Plan
5) Buy components
6) Build
-Jeb
PS- Didn't look at this post for two days because I wasn't quite sure what "Storking" was... ;)

 

The process of being a stork....oops. typo. So, how do you know what counterweight size to use? Looking around, I have not really seen any measurements for this listed.

I already have SCAT 5.7" forged and bushed I-beams in my garage.
I am most likely going with the SCAT Nodular Iron crank
Since this discussion, I am thinking some forged pistons now, probably some TRW's.

So, how do I find out if the counterweights are the proper size?

As for forged cranks, that is beyond my budget. I'm a low paid jet mechanic, so just getting the thing together is going to break me. I don't plan on going beyond 450 anyways, that seems to be that magic number where everything breaks.

And since the block is probably junk, any ideas as to where to find one. I'm in the process of calling all the local junk yards, but to no avail. I found one from a Caprice, but I want to find out if I can use it or not. I'd prefer to have the Vette block anyways because I am sure there is something that would screw me over if I used one from a different car.

So far, I have found that they have 2-bolt instead of 4-bolt mains and 1 instead of 2 knock sensors.

 

There's no such thing as a low paid jet mechanic! ;)

Seriously though, most crank mfg's now put more meat in the counterweights all you have to do is ask if they can be either externally or internally balanced. As for blocks, LT1, good luck on finding a 4-bolt. Grab you a two-bolt and install ARP main studs, for your power level that will be more than adequate.
-Jeb