Block filling

[LTb1ow]

What are your guys opinions on this? Is there a line between street use and strict race only?

This is assuming you are making a 383 and have no problems with hitting water, so no sleeving needed.

[NJSPEEDER]

I wouldn't do it on the street.

Filling the block does add a good amount of strength, but it also retains heat for a lot longer. If you were at the track with 40mins+ cool down time between runs like in most competitive events it would be fine, but for cruising around it would be a PITA.

[JSPERFORMANCE]

For serious horsepower cars that are more drag oriented no problem. A cruise on the street now and then is ok too but the hotter the block gets the tighter the bottoms of the cylinder walls get.. Long duration abuse would cause a real short engine life span.

[LTb1ow]

In one of the books I have been reading, the author says that the bottom end should not get that hot and should be fine to be filled. He says the heads are the hottest part and the area around the crank should be fine.

Any thoughts on that?

[JSPERFORMANCE]

When filled the block gets much hotter than if it was not. While the source of the heat is the top the entire engine will dissipate it.

[LTb1ow]

Yea thats what I was thinking. Sucks cause most books are hazy on street versus full out race engine builds.

[JSPERFORMANCE]

That is why knowledge based on actual experience is more valuable than reading anything on the internet or in a book.

[LTb1ow]

Agreed.

But I am a full time college kid, so going to hang out in local speed shops or drag strips is tough. So I am trying to research with books and of course the internet.

[JSPERFORMANCE]

Thats fine, just dont believe everything you read.

[LTb1ow]

Are there any other ways to strengthen the crank from walking?

I also was reading about doweled mains to prevent frettage of the mains, but that would require an aftermarket block correct?

[JSPERFORMANCE]

splayed caps usually are fine.. By the way what are you building, something with 1000+hp? block stability of the block usually isnt a problem until you hit around the 700hp range in most late model small blocks.

[LTb1ow]

Dreaming, sorry if you thought I was building something crazy.

I just have been doing a lot of reading of people's builds etc.

On the topic of splayed caps, some argue that straight 4 bolt mains are better on an GenII because there is more "meat" for the bolts to grab. But I would think that running a splayed cap would help the downward forces and the side to side more than a straight 4 bolt.

[JSPERFORMANCE]

original two bolt block with 4 bolt splayed conversion is better. if the block is already 4 bolt than that is fine for most applications under 800hp

[LTb1ow]

I wish I had a stock 4 bolt mained LT4.... That would be nice.

On horsepower ratings, is there a difference in say a crank for nitrous and a crank for boost? If the both made the same peak HP, the nitrous motor would put more of a shock on the crank right?

[JSPERFORMANCE]

yes

[LTb1ow]

I have read of a few things you can do to a crank to make a few more horsepower. Knifing the edge was the one that intrigued me. Does that really work? If you ran a deeper pan wouldn't that effect be lessened?

[JSPERFORMANCE]

knife edging is a good practice but usually leads to more time spent on the balance machine and possible need for mallory metal which is very expensive. not worth doing to a stock crank but can be worthwhile to a decent aftermarket piece.

Deeper is not what really makes the difference but you are on the right track, oil control is a place to find some good power.

[LTb1ow]

So an aftermarket crank will not come with any "tricks" done to it to maximize power?

[Tru2Chevy]

So an aftermarket crank will not come with any "tricks" done to it to maximize power?

I would assume that would depend on the crank.

- Justin

[JSPERFORMANCE]

^^^^what he said^^^^

[LTb1ow]

To keep on going here with the questions if you guys don't mind, is there a point where a fully forged motor will not make as much compared to a cast motor? Assuming no power adders. I would think a lighter rotating assembly would rev quicker,last longer and make more power?

[JSPERFORMANCE]

Good forged pistons ARE light. The forging is to make the parts stronger not build horsepower.

[LTb1ow]

Well yes, but I thought a forged setup would weigh less than a cast setup. And as for building horsepower, I am just thinking if the engine is never going to see boost or heavy amounts of spray why build it overkill?

What is your definition of a good piston? Mahle? JE?

[JSPERFORMANCE]

In general forged parts are heavier due to the density of the metal. Good pistons like JE, Ross, and Diamond use CNC machining to lighten the piston and give it the desired profile.

By the way, in most cases we are not talking about off the shelf parts.

[LTb1ow]

Ok, heres another question that gets thrown around a lot. 5.7 versus 6 for rod length in a 383.


Although, since we are talking custom parts, you could get a nice set of 5.85 Olivers... ;)

[JSPERFORMANCE]

Longer rod = more leverage on the crank and less side load on the cylinder walls.

[LTb1ow]

Longer rod = shorter piston skirt I thought too though right?

[JSPERFORMANCE]

yes, well not always, depends on the design but the pin does need to move higher up in the piston though

[LTb1ow]

And a longer rod may require more cam clearance etc I think too.

Ah engines, fun stuff. Much better than math.

[NJSPEEDER]

Clearances for the block skirt, wrist pin, PTV, and everything else exist in every motor. Doesn't matter what you wanna put in it, a proper build will check it and do machine work as needed.

[LTb1ow]

Agreed, but with longer rods or bigger rods you face more area to trim away. And I think you have to run a small base circle cam in some cases right?

(BTW you didn't have to delete those posts, appreciate it though)

[NJSPEEDER]

It all depends on the math and the clearances. There is no automatic do this and you have to do this. Some brands have bigger or smaller castings and the way some cams are cut they just naturally offer more room.

You need to have to start picking the actual parts to be used before you can plan to do any of that kind of machine work or spend extra time/money looking at a different cam.

[LTb1ow]

Yea, I know, I just like speculating and trying to learn these things.