Scalpel

iTrader: (4)

Why are stroker motor tolerances "looser" than factory motors? Is it because of the stroker motor's internals being made of a different material? Could a stroker motor be assembled with tolerances closer to a stock motor (tighter tolerances) and what would be the pros/cons of that?

I just like to know why things are done certain ways

Country Boy

iTrader: (24)

I would have to say thats its the parts manufacturer whos tloarences that are looser, like for the bearings, Im sure they have a min. and a max tolerance and its not the same as a stock tolerance. Same with the rods, they have a certain tolerance on the crank journal they can be between. Also, stock motors are tight because they are made to last 100k+ miles with minimal issues.

Scalpel

iTrader: (4)

Why can't stroker motors be made to last the same amount of time?

They are usually built of much better parts and materials. Crank, rods and pistons are usually all of much greater strength.

Dave Carney

The pistons are often forged, which requires a looser fit for greater expansion, then the stock hypercraptic units, which expand very little.

Patman

You mean clearances right? There is a difference between the term tolerance and clearance.

Scalpel

iTrader: (4)

Patman, I guess I don't know the differences. Fill me in on the differences and why they are different in a stroker vs stock motor. Thanks.

Joel_SS

iTrader: (8)

I would like to know as well..

robertbartsch

Our stock non-forged pistons don;t expand as much as forged pistons....so the piston/bore clearance is tighter...

Beast96Z

iTrader: (21)

A motor that has more clearence can move more freely, thus making more power. There are negative effects to this though, such as oil consumption. Diffrent shops have diffrent method of doing things. I would say you could go a little more loose on a nitrous motor, but would need to be a little tighter on a blower motor due to the boost. Lots of all out motors might be set loose cause they know they will be rebuilt in due time, but street/strip car would be built "tighter", so you don't burn lots of oil and smoke alot.

phenyxTA

Ditto on what beast said. With looser tolerences there's not as much drag and your motor can rev faster with minimal resistance. The factory has it's reasons for the tighter tolerences, including oil consumtion issues and excessive piston slap. It all depends on what your priorities are.

HumpinSS

iTrader: (1)

Tolerance is within a range and clearance is set closer or farther awys from a specified tolerance. Hope i didnt state the obvious

Scalpel

iTrader: (4)

The looser tolerances = less friction = more HP makes total sense. Thanks for that info. So, it would be possible to make a stroker motor (all forged internals) that would be very good at preventing oil blow-by, etc, correct?

HumpinSS

iTrader: (1)

No the looser the clearnaces = less friction = more HP just as long as you dont get carried away and go to far beyond the tolerances.

Tolerances (eg +- .002) meaning if you are supposed to have a clearnace of .482 you can either run .484 or .480 clearance and be fine

TTopJohn

This is what I want - a stroker (or all bore engine) that has the factory 100K + mile lifespan with no oil usage, etc....

Should be possible with forged internals, factory applications have used forged pistons with no problems.

Scalpel

iTrader: (4)

Ok, sweet, thanks for the clarification.

Nine Ball

iTrader: (38)

Sure, you could build a stroker to last as long as a factory engine.

1. Custom hypereutectic pistons
2. high tension piston rings to scrape more oil
3. low lift, low duration camshaft
4. 6K rpm rev limiter

Ummmm, no thanks

Tony

Scalpel

iTrader: (4)

Tony, aren't they referred to as "hyperpathetic" pistons? lol

Chicago Crew UnderBoss

iTrader: (1)

Here's my million dollar question: From what i have seen alot of these stroker motors have oil consumption issues (about 1 qt every 700 miles are so). Will this type of oil consumption set forth above lead to excessive carbon deposits and build up on the forged pistons and in the combustion chamber after a certain amount of miles and will these deposits cause the stroker LS1 motor to begin to detonate and have other significant problems as the motor acquire more miles on it (say 40 to 50K) miles?

TTopJohn

Exactly! It wouldn't make as much power as an all out stroker, but it would be factory reliable and make WAY more power than the factory engine. Precisely what I want - don't need to drop 10,000 on a new stroker and then have to go back into it 3 years down the road, I want it to be as durable as the factory engine.

Scalpel

iTrader: (4)

I agree at least that these options should/could be made available to the average Joe-schmo that just wanted a big cube daily driver that didn't care to get every ounce of HP out of their setup. I know most shops want to debut their motors with the most power and that's just common sense but they could put a little asterisk claiming "Different pistons/rings and camshaft/valvetrain could be changed for a less aggressive setup but more consumer friendly, i.e. less oil burning, longer valvetrain life etc." Somepeople just assume that a certain motor package just is what it is and couldn't be tweaked above or below for different uses.

I wonder what a 427 would cost that had:
block
steel crank/forged crank
non forged pistons/rods, just normal material
decent set of heads and a mild cam/valvetrain

I bet the price would be significantly less and you'd still have a TQ monster with factory engine reliability. Granted you won't be pumping out 126+ MPH in the 1/4 and it wouldn't be too wise to spray the motor too much (<100 shot) you'd have a really solid TQ monster with zero to no worry.

I wonder how much power would be lost with tighter tolerances, hyper pistons, and a mild cam setup. Heck you could still go aggressive on the cam as long as you had the valvetrain for it. Then your only maintenance concern would be servicing the valvetrain periodically.

I just like throwing ideas out there.