High mileage 408s

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MoparDreamin

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I never really see 408s that have anywhere near 100k miles on them. Do any of you guys have "high mileage" stroker motors ... more than 40k miles?
 
No. I dont think you'll see many that reach 50-60K without some oil use issues unless they are in a low rpm application. The pistons are just too short. Most will be bad enough using oil at 20-30 that you'll retire or freshen it. These are not designed for extended longevity. I would suggest that if that is what you need, build a 360 instead.
 
Not looking for longevity out of a 408. Im just curious.

So short pistons do what? Are we talking ring failure or bore distortion or ....?
 
chrysler long rod engines [most all] give less rod angularity at 90*

I believe that if a 400 chevy can go what ever 100 miles, so can a 4'' crank sb dodge.

the rod ratios are close-1.48-chevy 400 vs 1.53-mopar 408 , which still does suck compared to the better factory ratios

What's relative is RPM's the engine see's throughout it's use/'Milage'
 
1wild&crazyguy said:
chrysler long rod engines [most all] give less rod angularity at 90*

I believe that if a 400 chevy can go what ever 100 miles, so can a 4'' crank sb dodge.

the rod ratios are close-1.48-chevy 400 vs 1.53-mopar 408 , which still does suck compared to the better factory ratios

What's relative is RPM's the engine see's throughout it's use.
Click to expand...
> The people who make rings, have tech seminars, and they say,main "reducers" are: thinner/lower tension rings(moly coated), better oils, zinc not withstanding and faster warm-ups. Rings have much more drag at 160F than say 210F.:glasses9: If were talking oem.400"sbc's, for 100k miles, they use"off-set" pins, carefully engineered to reduce rocking and wear in normal use. Most of our stroker kits Do Not have off-set pins,(most aftermarket piston mfgr's don't bother). I consider this a big wear factor, in the long run. There is "Less" extensive load at turn-over, with off-set pins(rod doesn't come to full stop at tdc.), and less rock because of off-set weight on valve pocket side of piston(heavier). TMI? :read2:
 
ateam said:
> The people who make rings, have tech seminars, and they say,main "reducers" are: thinner/lower tension rings(moly coated), better oils, zinc not withstanding and faster warm-ups. Rings have much more drag at 160F than say 210F.:glasses9: If were talking oem.400"sbc's, for 100k miles, they use"off-set" pins, carefully engineered to reduce rocking and wear in normal use. Most of our stroker kits Do Not have off-set pins,(most aftermarket piston mfgr's don't bother). I consider this a big wear factor, in the long run. There is "Less" extensive load at turn-over, with off-set pins(rod doesn't come to full stop at tdc.), and less rock because of off-set weight on valve pocket side of piston(heavier). TMI? :read2:
Click to expand...


As my friend would put it ''grandma don't wanna hear pistons rattling in her brand new car''

wear less from off set pins?, is that what you are saying?
 
MoparDreamin said:
I never really see 408s that have anywhere near 100k miles on them. Do any of you guys have "high mileage" stroker motors ... more than 40k miles?
Click to expand...

Now we are getting why the factory did not use 4 inch strokes, longevity. Why even the 360 wasn't pushed as a performance motor, no forged crank was ever made by factory mopar for passenger cars or trucks. Shorter pistons rock more in their bores as they go up and down.

GM and Ford went with 3 inch strokes on the 283/289/302 motors and 3.25 on the 327's. True the 454 had a 4 inch stroke but it was a higher deck block with longer piston walls.

I got 600 miles on my 340 now and if gas was $1.50 it likely have well over a 1,000 miles now. I didn't go stroker cause partly the cost but am glad in a way now I went with a 3.31 stroke. Motor makes good power too, with a 10 inch converter and 3.91 gears torque seems great as well.
 
I had an auto shop teacher one time say if an engine was never shut off after being started , it could idle for 10 years straight [filters/fluids regular service intervals of corse]

start up is the most common and 1 of the hardest on an engine.
so is overheating, pinging/detonation, and low/high oil levels and running too rich etc...
 
I say start up wear is highest for normal motors. Normal motors don't crank out 400+ hp for 10-15 seconds. Why race engines get torn down after a 500 mile race, even thou it might have been started just a few times.
 
Interesting thread for sure. I wonder how long my 408 will last. I do plan to take great care of it, use only the best oil and fuel, and proper start up/warm up...It will be a daily driver... summer, winter, spring,...so only time will tell. Guess when the time comes, I'll let yall know. LOL
 
Mine's using an overdrive trans which will greatly lengthen it's life.
A large part of the longevity issue is low gears and high freeway rpm from three speed autos...

I decided to run a tighter .0045 piston to wall clearance too. We'll see if that helps any.
The less rock, the better.

Either way though...who gives a ****? Most of the 408s I see in cars are driven maybe a day a week, sometimes less. At that rate it will last forever.

What smallblock engine built to make 500 horsepower lasts 100k miles anyway? There arent any! They're all gonna be burning some serious oil and running like crap if they live that long.

I'm not worried about the motor anyway. I'm more worried about the trans since those are what I have a history of killing. I usually kill one per year.
 
Yeah an OD trans helps, too bad its so weak.

My engine shop was surprise to hear I put 600 miles on my car in one month, lol. The cost of gas is keeping it down, ha ha.

If you drive you car one day a week heck it doesn't matter. I see life as short, too short to let my car sit all week. Again if gas was cheap I be on the road right now, ha ha
 
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