How much HP or Rpm can a stock bottom end with stand

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maca

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Hi all
On my quest for more HP I never really hear of anyone talking or mentioning their bottom ends failing apart from too much HP on aftermarket cast cranks. I have a 360 magnum with a stock bottom end. I have 430 RWHP at the moment and it seems 100% fine. I don't know if its HP or revs that kill a bottom end but I don't rev it past 6500rpm. Most of the time it doesn't go past 6000 rpm. I have been toying with chasing some more power for a couple of street meets coming up. My thoughts were either upping the boost or E85 or nitros but before I get carried away I thought I would throw this out there.
Anyone running big HP on bottom ends without 4 bolt mains etc etc?
 
There's a lot of variables. The crank, the machining of the block and crank, the balancing, the weight of the parts, the type of power being produced, the fuel... It all factors into longevity. Anything you can do to make the machining more precise, the balancing specs tighter, and the parts lighter will all go a long way to add life span. Typically, assuming the rotating parts are of decent quality, the main caps move first. Then the caps themselves deform. Then the block fails. Adding extra cap bolts simply adds stress to the block - it won't solve any cap or power issues. Girdles won't address the block issue either. So once the expected power output reaches a certain "critical mass", you should upgrade to a better block. The opinions on what that critical mass is vary greatly - so talk to your machinist. Ultimately it's your money and his warranty & experience you're paying for.
 
Thanks for the reply. My engine was checked by him for all my tolerance's before i built it. I have chatted to him in the past and his opinion is don't rev it over 6000rpm but we never really discussed HP
There must be a heap of guys running decent HP on there small blocks on here on a stock bottom end. Anyone got some numbers numbers they have been running on a stock bottom end?

What is the job of a girdle?
 
Half hard fill water jackets, main studs, and stud girdle. With the above mentioned quality machining.

Stud girdle ties the caps together to prevent cap walk
 
Two engines that make the same power but do it at different rpm's will have different requirements.

As an example, a 500 HP engine that turns 6000 will have less stress on the block then the same HP turning 8500.

Keep in mind that long strokes, low rod/stroke ratios and short Pistons reduce the limit a block can take.
 
Search it you will be surprised what they take, your engine is not close.
You are safe if the machining is right.
 
Thanks guys
I did think the rpm was a big factor so that's why I try not to spin it too far even though it's soooo tempting as my engine is still climbing in hp at 6500rpm.
Before I had a 360fwhp engine that gave me 270rwhp so I lost quite a bit. So now I have 430rwhp I am guessing I must be around 550fwhp now roughly. I wouldn't mind giving it some nos or e85 or more boost at the track but I have to find out what will work best for me as I have no intercooler and currently running 8 psi. Not sure what max boost I can run. I need to read up on it I think
 
maca said:
Thanks guys
I did think the rpm was a big factor so that's why I try not to spin it too far even though it's soooo tempting as my engine is still climbing in hp at 6500rpm.
Before I had a 360fwhp engine that gave me 270rwhp so I lost quite a bit. So now I have 430rwhp I am guessing I must be around 550fwhp now roughly. I wouldn't mind giving it some nos or e85 or more boost at the track but I have to find out what will work best for me as I have no intercooler and currently running 8 psi. Not sure what max boost I can run. I need to read up on it I think
Click to expand...

Under a 3.600 stroke will live to 7500 if the oiling system is up to snuff. Boost is another matter altogether.
 
Unfortunately, the only way to definitely find the bottom end limit is to push it to the point where it goes boom! Mythbusters should be work on this question some time, would be a good show.
 
thanks for the input. One day when I am ready to build my next engine will rev her to 7500 and see what it can do;)
for now it will remain inj the safe zone.
What boost is anyone running on there small blocks as I would love to run more but not sure what a 9.3 comp engine with no intercooler can take
 
I had a box stock 340 in a 73 Charger I routinely spun to 6900-7100 every single weekend at the drag strip. It ended up crackin a piston and I drove it for almost a year like that on the street till I went through it.
 
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