Stock block max?

[Mr.Slave]

I have asked this question on other forums and to no avail. You guys seem a lot more informed than the others so I will ask you. What is the most hp you can run with a stock block and not have it grenade? I have all forged internals and the only thing that is stock in my block. I'm expecting roughly 350 @ the crank with my setup and I have that Big Shot wet kit from NOS that supports up to 300 hp. I'm only going to run a 150 shot when I get the car dialed in, but can I go more? I have heard something about gapping the rings if you get past the 175 mark with the gas. Is that something I should do before I get the motor back together?

[qkjuicedpony]

it all depends on how long you want it to last.in my opinion about 550 to the tires is the limit.sure you can go more but for how long.i have seen and wrenched on too many cars making 550 that are still alive and running.

[LeeH]

It depends on the quality of tune, If you get into detonation you can kill it at at low HP levels. Numerous things can make a stock block last longer at higher HP levels(internally ballanced, keep the rpm below 6500, Tune) but you are still taking a chance at anything above 450HP, Of course tune is the big factor here. Early(68-74) blocks will go above 550HP(FWHP) without a problem on a consistant basis, I cant stress enough that tune is the big killer.

[LeeH]

Originally Posted by Mr.Slave

I have heard something about gapping the rings if you get past the 175 mark with the gas. Is that something I should do before I get the motor back together?

Its mandatory due to thermal expansion, Remember HP is heat energy. More HP = more heat. Your piston to cyl wall clearance will have to increase due to this added release of heat, Pistons will expand more. On a bottle motor .004 - .005 piston/cyl wall clearance is what I run with a good piston. That brings up another factor to consider, What piston are you going to use? Brand? Material? etc?

[Mr.Slave]

I have a 94 block unfortunately, but like I said before thats the only thing that is stock. Before I run the nitrous I will have a TwEECer and I will have it professionally tuned on the dyno. So having said all that, I want the motor to last about 2 yrs. or so, so where would be a good place to set the hp at the tires with the NOS?

By the way, the rest of my bottom end consists of a Ford Racing steel crank, Eagle SIR I beam rods, and Speed Pro 10.13:1 forged pistons. The block has been hot tanked and bored .30 and it was line honed with my Trick Flow main girdle in place.

[QWKSNKE]

Since "Slave" is talking about a nitrous motor, would torque not play a factor in block splitting power? Seems to me a 200 shot would be the most you would want to spray on a stock block. That should put him around 625 (probably more with his compression) rwtq on the spray

[Blown 5.0]

I'm not sure of the H.P., But i bought a 95 Cobra crate engine in 96. I ran this motor till 04, not only did i spray 125 horse shot, it also saw 8 psi of boost. This motor pushed a 3400# car to 730s many times, (8 years worth of passes, and i go racing regular) I sold this motor to a friend to go in his daily driver, 100 thousand miles later he pulled the heads because he thought he had a head gasket leaking, ( it was the intake gasket). The hone marks were still visible, no ring grove at the top. He put on new gaskets and is still going today. Did i mention he also has a powerdyne supercharger that has been on the motor for a couple of years? The TUNE was rite on both cars, I think the tune is the key factor in making a motor live. Tune and treat the motor rite and it will live a long and happy life. P.S. we also have a stock block motor in another Mustang, Which sees 8 psi of boost,( from a roots blower) and 150+ horse shot, car goes mid 6s, he don't run the car much, maybe 20 passes a year. But this motor has survived for about 4 to 5 years.

[Mr.Slave]

If I ran a 200 shot would the ring gapping factor come into play or would I be ok with the standard ring gaps I have now. If I need more gap how do I go about doing this with bore or piston size?

[LeeH]

Originally Posted by Mr.Slave

If I ran a 200 shot would the ring gapping factor come into play or would I be ok with the standard ring gaps I have now. If I need more gap how do I go about doing this with bore or piston size?

Like I said before, Yes. You need both more piston to cyl wall clearance and more ring end gap clearnace. Your machinist will bore the block and hone the cylinders to size according to the pistons(make sure you tell him what your going to do with the engine). Then you will size each ring to its bore gaining end gap clearance by filing the ring ends, Its good to use a ring end gap file to keep the ends square. Use a feeler ga. to measure end gap. I use a piston(crown down into the bore/upside down) to square the ring in the bore to measure end gap(ring needs to be about 1.5 inches down in the bore).

[QWKSNKE]

I am an anti ring filing person. I went with file fit rings on my first build and hated it.
On my last freshening of the block I went with standard gap rings and probably will stay that way on all of my personal engine builds regardless of motor combo