how much rpm can a stock botom end hold?

 

More than the stock valvetrain will ever let it turn.

 

stock 350 bottom end? if it has every thing to turn that high

 

it can turn 7500... or more... how many times? who knows?

i am turing a stock LT1 shortblock to 7,000 sometimes.

 

Everything in my 305 botom end is stock. Turns 6k on a regular basis. has been 6500.

 

With the moon full, a crushed clove of garlic in your underwear, face smeared with royal jelly, an eagle feather hanging from the mirror, the rear jacked up like a mo' fo', a pontoon strapped to the top of the car and Chuck Norris chasing behind....... 14,392rpm.




Yes, that answer is about as legitimate as the question.

 

Until it gets damaged.

You talking about ONCE? Every time you use it? Make meaningful power? Continuously?

Next:

What level of failure risk are you willing to tolerate? i.e. if you had 100 stock motors, are we talking about the RPM where ONE blows up under the aforementioned circumstance, or 10 of them, or 50 of them, or all of them?

OK now that you've decided on that:

What do you consider "hold"? Would this be simple survival (all parts remain inside the oil pan), can still run one more time, will last another 10,000 or 50,000 or 250,000 miles, or suffers no detectable degradation at all?

Some people will tell you 7500 RPM. Some people will tell you that if the motor has been started and run AT ALL, it's compromised. The truth, for most of us, is somewhere in between.

 

To get a little closer to useful information.... I wouldn't want to see over 5000-5500RPM. The stock rod bolts are notoriously weak. Upgrade that and I (personally) would be able to sleep well at night with 5500-5750RPM range.
With entry level aftermarket rods with ARP bolts (say OHIO crankshafts $159 specials), and $20 ARP main bolts, and a balanced rotating assembly, 6000RPM or even 6500RPM is something i'd be comfortable with.
I didn't balance my rotating assembly, so I never see over 6000RPM. Heck I don't even think i've seen over 5500RPM.

 

You didn't balance? When I did that on my Formula the thing basically shook like a rock polisher. Didn't last long before I had to rip the engine back out. It was tearing up the bearings. That's what I get for buying a rotating assembly "kit".

I just spun my 92 to 6641 rpm with bad results. Stock bottom end. Non-stock top-end.

 

I don't think a lot of people get their rotating assemblies balanced. Mine runs pretty smooth. After 6000RPM it becomes an issue. I'm using AL bearings, i'll be tearing it down this winter to give it a once over (and maybe more cam), so i'll know then.

 

That's just my experience. From now on, if I replace anything, i'm getting it balanced.

 

If you're running a bunch of stock, or stock replacement parts, you might luck out and be close enough to a balanced configuration that you don't have vibration issues. If you're using aftermarket performance parts, especially if you have a new crankshaft, then you won't be so lucky.

In either case, its best just to have it balanced. It's cheap, and then you don't have to give it a second thought.

 

My engine is as follows:
speed pro forged pistons 10.5:1
rods and pistons wieghed and matched w/ new ARP rod bolts
crankshaft cut and balanced

What would be a safe upper limit. By safe I mean I want this engine to last at least 100k miles. Also, how would I know if I've gone too high (other than the engine blowing). The torque feels like it peaks at around 4500 RPM. I just got the car and I'm trying to figure out shift points and what not for when I take it to the track.

 

If the torque peaks at 4500, you don't need to go much beyond that.

 

It was my understanding that when your racing, you want to take it up till your HP drops off to get lower ETs. I know a lot about cars, but I'm new to racing, especially 1/4 mile.

 

i spin a GM stock bottom end to 6800 on a regular basis.










you can too! just buy a six bolt main engine from GM.

 

What cam do you have nbays? That's what determines your shift point, that and heads (ie. when it makes power).
Try shifting at 5000RPM at the drag strip, do it 3-4 times, make sure you can get a consistent timeslip. Then try at 5500RPM. If it's faster then you're doing better.

A dyno session can help you take the guesswork out of it, but runs at the track are more fun

 

This is from the listing when I bought the car.

fully ported edelbrock performer heads.
Trick flow 1.5 roller rockers
Trick flow hardened pushrods
ARP head bolts and rocker studs
comp cams hyd. roller 230/234 528/539 110lsa

 

ok, that's the xe276hr I think. Should be 230/236 IIRC.
Quite common. Probably a 6000RPM shift point or slightly higher.
But yea, only track testing will find out what gives the best ET.

 

Thanks for the info. I figured I could/should take it higher, but I wasn't sure. The previous owner did install a high rpm tach, presumably because the stock tach stops at 6k. I'll try shifting around 6k and go from there.