the breaking point

mustangmods

Member
Oct 25, 2005
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What is the max HP a stock 302 can maintain? Like say I have a stock 302 block that has several bolt on upgrades, how far can I go until upgrading the block becomes an issue? Same question goes goes for the AOD guys out there. How much power and torque can a stock AOD take with a 1900 to 2300 stall and with a shift kit? The point at which mass migration of stock parts happen is inconsistant , i'm just wondering if any of you guys might have some numbers.
 
block wise.. id say 500 horse.. i know a couple guys with 347's are 450 horse that arent breakin.. but alot of people on here are 500 horse and stressing the blocks to hell lol
 
It also depends upon the power delivery. Some methods are harsher than others. And if you never get on it hard, you can have 800 HP on a stock block. Lots of caveats.
 
I DON'T HAVE PERSONAL EXPERIENCE IN THIS MATTER BUT FRIENDS OF MINE THAT HAVE EXPERIENCED IN THIS MATTER SAY A STOCK 302 BLOCK WILL CRACK STRAIGHT DOWN THE CENTER IN A SHORT AMOUNT OF TIME WITH ANYTHING OVER 500 HORSEPOWER AND THATS IF YOU APPLY THE TOTAL 500 HORSES. I WILL NOT PUT OVER 450 HORSE POWER ON A STOCK BLOCK, IF IT WERE ME.
 
It all depends on the tune, and as HISSIN said, how hard you drive your car. I've been over 500rwhp since june with no problems at all. I've only done two 1/4 mile passes though. Every once and a while I'll row through the gears and do a burnout here and there. Buuuuuut, even though the engine is doing alirght, my tranny is about to explode.
 
I knew the stock blocks were fairly durable, but I had no idea they could take that kind of stress. Its impressive..
How about the stock AOD? I've heard of problems with the pump input shaft breaking but never at what point this could occur. Also you guys have any suggestions on gear ratios? I'm doing a resto mod on an older mustang with an 8 inch rear end. Right now it has a 3.00 posi. I'm building a strictly street car so 1/4 mile times are not my concern. Just a good well balanced mustang. The engine I'm in the process of making is going to be in the 250-260 hp range, I hope. I just wanna be sure that my Stock AOD can take it. I plan on rebuilding it with new clutches and a shift kit with a bigger trans cooler but theres no point in doing so if it burns up, ya know what I mean
 
bill302 said:
I DON'T HAVE PERSONAL EXPERIENCE IN THIS MATTER BUT FRIENDS OF MINE THAT HAVE EXPERIENCED IN THIS MATTER SAY A STOCK 302 BLOCK WILL CRACK STRAIGHT DOWN THE CENTER IN A SHORT AMOUNT OF TIME WITH ANYTHING OVER 500 HORSEPOWER AND THATS IF YOU APPLY THE TOTAL 500 HORSES. I WILL NOT PUT OVER 450 HORSE POWER ON A STOCK BLOCK, IF IT WERE ME.


This is almost word for word the same thing that a couple of engine builders have told me. That's exactly where I'm at too. It's my understanding that regardless of good rodbolts and studs....stuff like that....at 500hp a stock block is like a grenade with the pin partially hanging out.
 
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578 hp

Its not how much , its how long you want it to last there's people making more than 600hp out there.

also the amound of Load you put on the engine I.E. Dyno or slicks at the track.
 

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mustangmods said:
I knew the stock blocks were fairly durable, but I had no idea they could take that kind of stress. Its impressive..
How about the stock AOD? I've heard of problems with the pump input shaft breaking but never at what point this could occur. Also you guys have any suggestions on gear ratios? I'm doing a resto mod on an older mustang with an 8 inch rear end. Right now it has a 3.00 posi. I'm building a strictly street car so 1/4 mile times are not my concern. Just a good well balanced mustang. The engine I'm in the process of making is going to be in the 250-260 hp range, I hope. I just wanna be sure that my Stock AOD can take it. I plan on rebuilding it with new clutches and a shift kit with a bigger trans cooler but theres no point in doing so if it burns up, ya know what I mean

The AOD and motor will EASILY take 260rwhp. As for gears, I would go with 3.73's, a nice kick in the pants gear that doesn't kill you on the highway and doesn't make first gear useless.
Some guys might say 4.10's with the AOD, its up to you.
 
I know of a couple of guys that have well over 400rwhp and their blocks are hanging in there. They all say that they're running safe tunes and are keeping the rpms below 6000. Most guys i talk to seem to think its the high rpms that kill the blocks more than high horsepower.
 
Holy crap!!! I've seen 302's cracked down the middle but never split in half... must have been one hell of a 1/4 mile run!
Great tech advice guys. Anyone here used FRP's wide ratio kits for AOD?
 
id agree with the high rpms killing the motor more then the hp. also, i dont think the first time you floor it with 500rwhp the block will go. my dyno tuner had a 650rwhp stock block 302 with an AOD that ran low 10's high 9's. he got 8 passes at those times no problems shifting at 6k. 9th run down the track and all hell broke loose. so the stock block can take a beating, but high rpms and high hp shorten the life. now i wouldnt go out and build a 650rwhp on the stock block but it is doable. after my pms i should be in the 500rwhp and im done! dont care if i still have the stock cam. 3200 stall and a good lsd and my DD/strip car is "finished"