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]

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]

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

[Italian LX]

. . . 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).
I'm not sure where you came up with the 1.5" number, but with a fresh bore, there would be no reason to go that deep.

Summit makes and awesome little device that sets the ring in the bore square and consistently. It's also adjustable for different bore sizes.

[coupe]

Mr. Slave...

If the Speed-Pro pistons were set up with an incredibly tight clearance and the rings were gapped very tightly for some reason, you may consider taking it back down if you want. But I can't see why it would have been built that way at all...

so, since your engine is already assembled, just hit it with the 150-175 shot and race it! :nice:

[Mr.Slave]

Yeah, thats what I'm going to do probably. Although I don't have the motor assembled yet, the block work has been done already and I am quickly running out of budget. I will just assemble it with the ring gap where it is already and just hit it with a 150 shot.

Thanks for all the input guys.

[coupe]

Well, since it's not assembled, make sure the gap is not too tight. That's your main concern. And also make sure you have a good harmonic balancer and that the flywheel/flexplate is the correct balance. That will help longevity.

[Mr.Slave]

What would be considered too tight? This will be the first motor I've actually assembled myself, but I will have my friend who has built 100s of motors helping me. The only thing is that, its not his motor, so I'm sure he wont be paying attention to detail as much as I would like.

[Italian LX]

What would be considered too tight?
Your sheet that came with your rings should give you the suggested gap range for each specific application.

[coupe]

I think .024 & .026 would be a good top & second gap. :shrug:

QWKSNKE set up his motor for a little nitrous. Maybe he'll chime in...

[QWKSNKE]

I think .024 & .026 would be a good top & second gap. :shrug:

QWKSNKE set up his motor for a little nitrous. Maybe he'll chime in...

I did not file fit my rings. I used standard rings on the last freshening of the motor. I bought file fits on the first set and we filed them to around .026 of an inch. That is what the ring instruction recommended for blown and nitrous motors.
File fitting rings encourages blow by and why I stated above that I would never use anything other than standard rings again

[Mr.Slave]

How much power were you making before and after the spray? Were you using a stock block or was it aftermarket?

[Italian LX]

I think .024 & .026 would be a good top & second gap. :shrug:

QWKSNKE set up his motor for a little nitrous. Maybe he'll chime in...
Those number sound familiar. If I can find my notes at home, I can tell you what I file-fitted my ring to. I set it up as a street motor running nitrous.

However, I only have 4000 miles on the motor and only about 5 passes with a 200-shot plate kit. The combination isn't proven yet, so my numbers won't benefit you any.

[coupe]

File fitting rings encourages blow by...

:think:

File-fit rings allow you to set the gap where you want it. Set it too loose, and of course there will be crankcase pressure issues.

Standard rings are just "file-fit" from the factory.:shrug:



Common practice is a little bigger gaps on power-adder rings. Second ring a little bigger (.002-.003) than the top ring, this reduces pressure between the two and possible ring flutter.

[Mr.Slave]

So would I be correct in saying that gapping has everything to do with the rings and nothing to do with the bore sizing? I was under the impression that I would have to rebore my block if I wanted to gap the rings. If its just a matter of resizing the rings then I'm all for it.

[coupe]

It has to do with bore-sizing. Sometimes, the bore is set up a little loose for certain resons...then if you have a standard ring for that bore (which may be setup .001 larger), the gap will be a little too big. File fit allows you to get the gap where you need it. It's liek fine-tuning the gap. But like mentioned above...can be a PITA.

[QWKSNKE]

How much power were you making before and after the spray? Were you using a stock block or was it aftermarket?

I had a boosted combo (14psi) when I did the file fit thing. I was using my bored over stock block (still using it). I disassembled the motor last fall after I sold the blower and freshened it up with new bearings and new standard rings.

:

Common practice is a little bigger gaps on power-adder rings. Second ring a little bigger (.002-.003) than the top ring, this reduces pressure between the two and possible ring flutter.
Actually my rings recommended the same gap on both.

Like I said, I had a bad experience with it and personally will never do it again. That doesn't mean if one of our customers wanted it done that I/we wouldn't do it.
So far Brian's car is having good luck with a file fit setup

[Mr.Slave]

I had a boosted combo (14psi) when I did the file fit thing. I was using my bored over stock block (still using it). I disassembled the motor last fall after I sold the blower and freshened it up with new bearings and new standard rings.

Have you used standard fit rings in an application that is over 500rwhp?

[QWKSNKE]

Have you used standard fit rings in an application that is over 500rwhp?

Do the OEM rings count? :D

I made 532 on the OEM shortblock

[LeeH]

I'm not sure where you came up with the 1.5" number, but with a fresh bore, there would be no reason to go that deep.

Summit makes and awesome little device that sets the ring in the bore square and consistently. It's also adjustable for different bore sizes.

Why buy a tool when you have pistons, The reason I say go 1.5 inches is it allows for enough piston in the bore to make sure rings are square.

[Mr.Slave]

Good stuff, love this site. You guys are very informative!

[Italian LX]

Why buy a tool when you have pistons. . .
Looks like you answered your own question in the same sentence. :rofl:

. . . The reason I say go 1.5 inches is it allows for enough piston in the bore to make sure rings are square.

The tool from summit sqaures the ring in the bore perfectly and it sets the ring only about a half inch down the bore so it's real easy to take the measuement.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SME%2D906002&N=700+115&autoview=sku

[LeeH]

Looks like you answered your own question in the same sentence. :rofl:



LOL,

Yeah I just use a piston to square them in the bore, Call me a cheap skate. ;)

[Dale McPeters]

LOL,

Yeah I just use a piston to square them in the bore, Call me a cheap skate. ;)

Don't worry Lee you are not the only one that still uses a piston to
square the rings in the bore to check end gap on the rings........:D

By the way it is almost time!!

[Mr.Slave]

I got the internals back last week and talked to the guy that did the balancing a little. he said go .005 to .006 of endgap per inch of bore on a nitrous motor. He said I could file my standard gap rings to accomplish this after I measured of course. Does this sound right?

[coupe]

yes.

fine.