Stock block strength, stroke versus rpm?

[af2]

OH and it is a 2 bolt studded 400 block With a girdle..... Going into my DIL's 57 4 speed car..

[PackardV8]

I generally stick to my "RPM is your enemy" mantra

Agree, Mark. I tell customers RPM is the most expensive horsepower; always go with displacement.

[cjperformance]

So longer stroke is a less stressful way to produce the same given hp level ? Is this why a majority of endurance and consistently hi rpm engines that need to live go for long stroke to achieve the hp at a lower rpm?

For a street some strip where low end and big mid range are the big fun factors and $ for a high rpm capable valve train outweigh the cost cheap/instant tq stroker kits and street practicality then yes big stroke is great.
Bracket race and last as op stated is not going to look at low rpm tq and will more consistently be used in the upper rpm area so in a loose sense is an endurance build. In "the given combo" the bore size is pretty much fixed due to the block, the piston used for each given stroke can realistically be the same weight or there abouts, so what is piston speed (1 major fatigue stress factor) between these 2 stroke options going to look like for the 2 ci combos to make the same HP ??

[PackardV8]

So longer stroke is a less stressful way to produce the same given hp level ? Is this why a majority of endurance and consistently hi rpm engines that need to live go for long stroke to achieve the hp at a lower rpm?

For a street some strip where low end and big mid range are the big fun factors and $ for a high rpm capable valve train outweigh the cost cheap/instant tq stroker kits and street practicality then yes big stroke is great.
Bracket race and last as op stated is not going to look at low rpm tq and will more consistently be used in the upper rpm area so in a loose sense is an endurance build. In "the given combo" the bore size is pretty much fixed due to the block, the piston used for each given stroke can realistically be the same weight or there abouts, so what is piston speed (1 major fatigue stress factor) between these 2 stroke options going to look like for the 2 ci combos to make the same HP ??

Corrected Piston speed is a method to accurately represent upper end stress on an engine, and is calculated as mean piston speed divided by the square root of the stroke/bore ratio. Piston speed stresses are on rods, rod bolts, wrist pins and pistons and to a lesser degree on the crankshaft.

The force of inertia is a function of mass times acceleration, and the magnitude of these forces increases as the square of the engine speed; double the engine speed from 3,000 to 6,000 rpm, the forces acting on the piston is quadrupled.

[Rowdy Yates]

I'm not the smartest guy block..... I've followed a few top notch builders, and when dealing with a stroker with a decent deck height so as not to have a crazy rod/crank ratio you will make the same HP at a lower Rpm. Fact! If I take the same stroker with more Rpm it will make more HP than the smaller crank. Simple formula of.... how do we make HP. You take a 376 I'll take the 408 same compression and peak RPM... Who makes better numbers thru out the Rpm band and has more under the curve? If the deck height and rod ratios aren't that bad stroker all day. Don't believe me I can show to different Ls builds 418 lq 4 and a 376 Ls3 both have bores of over .065 both rev'ed past 8500 more like 8800. 12.5 compression for both 790ish vs 829 in HP and I'm sure it had more power through out the curve and under it. Again Fact...... This is not formula 1 bigger bore is always better yet having not enough stroke is a bummer. 3.9 vs a 4 inch crank is no major difference...... 3.5 or 3.6 and you need Rpm to keep up. What requires more maintenance Less Rpm or more Rpm? Or harder on parts.

[Rowdy Yates]

Update the parts list... Add compression better H/I/C, vacuum pump etc..... More HP also you can bleed off some cylinder pressure with a bit more RPM..... +11.5 compression with pump gas. Old builds just need some updating.

https://www.hotrod.com/articles/ccrp-11 ... ock-mopar/

https://www.hotrod.com/articles/inch-mopar-stroker/

https://www.yellowbullet.com/forum/show ... ?t=1978746

https://www.yellowbullet.com/forum/show ... source=amp

Update to your liking.... We are dealing with nothing more than a air pump add compression and Cam lift with Rpm.
Get in touch with M. Jones and get a asymmetric solid roller or a Low lash solid. 630ish lift. Possibly get 700 at around 7200-7500 if the induction can hang. Thinking of a simple 402 Ls2 that made 707 HP without all the hoopla 11.5 Comp and a solid roller @7200. Key thing is if* the heads can flow over .300 and you find a less restrictive intake. Again just a air pump.

[fastblackracing]

I always see these stock block threads and am compelled to share some first hand experience on this.....
It is not always just the possibility of breaking the components and losing the $$ invested which may or may
not be an issue for whomever the build is for...

But the when building to a power level that is exceeding the known sensible limits, yes I get it we all have
budgets, some bigger, some smaller and we all want to go as fast as possible.....you should really think about
what all can happen if this thing grenades and gives up the ghost in a big way?

In the case of a stick car when the block separates and comes apart the clutch can become locked up and
may not be able to be released which will lock the back tires as you are then driving over your oil and coolant side ways with little control of your car....think about that for a minute...It happened to my son
with his stock block 5.0 that was making 525ish RWHP when he shifted into 4th.

Here is a pic of what was inside when I pulled the pan off......exactly as it was no staging or embellishing the pics.....we put the block in the wheel barrow rolled it to the side yard and dumped it on the ground as it was not possible to bolt it to the engine stand.

[pdq67]

I will say this again!

I want to build a 1st Gen. type SBC block that will be a 3.155" b x 3.00" stroke 325" engine.

I am going to use a flat tappet solid lifter cam it so that I can shift in at 8,000 rpm and above.

I read where several of the guys have hit 10,000 and even 11,000 rpm with SBC engines. I forget the B&S combinations but I am thinking they are based off the old 283 block?? 287" and 292" engines here...

Now I would also like to make up to at least 1,000 to 1,200 Hp out of it IF I decide to blow it!!! I'm figuring about 475 to 500 Hp N/A here...

So I figure that I need to start with a ductile iron block so who sells one?

pdq67

[Rowdy Yates]

Just get the correct Dart block for you app.

[pdq67]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Does Dart sell a real 1st Gen. SBC ductile iron block?

Not a CGI block....

pdq67

[Rowdy Yates]

What are you talking about there are plenty Normal CGI Dart blocks making more than what your talking . I've never seen or heard of the block your looking for. They make ductile sleeves never seen a ductile iron block.... If so Show me.

[woody b]

I'm certainly not an expert, but IF everything is balanced correctly AND the oiling system works the block doesn't care about rpm given the same basic power level. RPM tears up the valvetrain.

[Rowdy Yates]

That's why stroke helps you can make the same HP with less RPM, bump up the compression and see what can be done. I know some factory blocks may not hold up to well to Rpm but there are things to help sturdy up a block.

[ProPower engines]

I am curious what is better for a stock block performance build that can approach or exceed the strength of the block. Say we are working with a Magnum 5.9 (360) Dodge.
What puts more stress on the block? Short stroke, say 3.59, versus long stroke of 4 inch? At .030 overbore the two motors will be 366 and 408 cubes.
If your goal is 625 hp, which i hear is a bit more than the stock 5.9 block is comfortable with, which will put less stress on the block? Consider this to be a bracket racing type of build that needs to get that 625 hp with the longest life.

If you are using a block from the era when Daimler was involved with the block casting and you are referring to the later 5.9 Magnum block with the changed lifter angle then is will live a long happy life.

A customer I have done many 408 combo's for regularly gets about 620 to 630 with great success in that they live.
the key thing to think about is
1 stiffen the main cap area best as possible with either a girdle of replacement caps or both.
2 Consider the engine mounts and the stress they apply to the block during launch. Solid mount are not always best for a street car.
3 Don't over tighten the accessory belts. If using a V belt they are the worst as they cause the crank to crack between the front main bearing journal and the 1st rod journal cause that is the thinnest and weakest part of the crank. Scat and Eagle do sell a stroker crank for a 408 combo but if you look at how they are made you will see what I mean there.

I have seen the drive belt system that uses a V belt used on many and part of the instructions for start up is do not put too much tension on the belts and check how the belt is sitting in the groove as some belts have the same number but the V dimensions are greatly different and don't always grab the groove right and slip thus they get more tension till the V is bottomed in the groove to the point where the belt just wears more and faster and the end result is a very over tight belt that slips but loads the crap out of the crank snout

[Krooser]

My 360 based 383 ran two seasons in a dirt modified without issues... 3.79 stroke... 575 hp.

When the engine grenaded due to driver error(no warm up, heavy oil, cold ambient temps) the engine seized one rod bearing breaking that rod and destroying three more rods and four pistons. Amazingly the block never took a hit.

I think the older 360 blocks have more strength than a magnum but I have never been a big fan of long strokes in any oval track deal. Those 4" chinese stroker cranks scare me...