Anyone have any info on piston to wall clearance for Speed Pro L2315NF30

[Meep-Meep]

Also weight in grams. Summit has no answers and I can't find anything on the manufacturer web site. I'm thinking this VMS-75 alloy is a high silicon type and will run close to the wall but I'd like a tolerance so I can accurately measure my result. I have a 383 I want to hone and rering but don't want to run the old style (looser) forged pistons that are in it.

Speed-Pro Forged Pistons
SLP-L2315NF30
http://www.summitracing.com/parts/slp-l2315nf30

 

[lewtot184]

if the oil ring groove is slotted at the skirts try .003". get a diameter measurement at the skirts 90 degrees from the wrist pin and a measurement at the bottom of the skirt.

 

[Meep-Meep]

Dug deeper and found a tech line for Speed Pro and got my answer. Minimum clearance is .0015". Weight with pin is 999g. W/O pin 781g. Compression distance: 1.920"

 

[Wing It]

Dug deeper and found a tech line for Speed Pro and got my answer. Minimum clearance is .0015". Weight with pin is 999g. W/O pin 781g. Compression distance: 1.920"

Hi, I saw this post on the topic of Speed Pro forged pistons. I have a 440 and I bought Speed Pro pistons for it that have the VMS-75 alloy. The box the pistons came in says "Minimum clearance .001". We have an older catalog that says .0015". We are thinking that we might want to go a little looser just because .001 or .0015 seems really tight. This is listed as a minimum clearance but they give no guidance on a maximum. Also, on Summit if you look at a parts listing for a 4.250" Chevy piston with the same alloy it says the clearance should be .004". Several other piston makers who make pistons with the same alloy list the clearance as anywhere from .0025" to .0055". What I would like to know is did you run them at .0015" and if so did you have any issues? Thanks for your help! BTW I am also in northern California (94546) and I am building a Superbird.

 

[forphorty]

.0015 sounds like cast piston clearances to me. Attempting to run any forged piston that tight seems like a recipe for disaster.

 

[justcruisin]

VMS-75 is pretty close to a 4032 piston, as far as I know they both run about 11% silicon. The instructions for my 4032 SRP's call for a minimum of .003 for a 4.200 bore to .0035 for a 4.6" bore. I don't think I would be game to run your pistons any less. Mine are in at .004". A little noisy at start up but they do quiet down.

 

[Meep-Meep]

Hi, I saw this post on the topic of Speed Pro forged pistons. I have a 440 and I bought Speed Pro pistons for it that have the VMS-75 alloy. The box the pistons came in says "Minimum clearance .001". We have an older catalog that says .0015". We are thinking that we might want to go a little looser just because .001 or .0015 seems really tight. This is listed as a minimum clearance but they give no guidance on a maximum. Also, on Summit if you look at a parts listing for a 4.250" Chevy piston with the same alloy it says the clearance should be .004". Several other piston makers who make pistons with the same alloy list the clearance as anywhere from .0025" to .0055". What I would like to know is did you run them at .0015" and if so did you have any issues? Thanks for your help! BTW I am also in northern California (94546) and I am building a Superbird.

Hey there. My block was honed to freshen it up so my clearance is a tad over .0015" and more like .002" - .0025". My project was put on hold because I had to move my shop so do not have this running. Years past I ran cast pistons at .0015" and had no issues. According to what I can find, VMS-75 contains 11% silicon and is similar to 4032, which runs tight in the bore compared to 2618. I would consider .005" to be too loose for high silicon alloy.

 

[33 IMP]

Looked up your 2315f in my 30+ year old trw catalog. It confirmed the info you found on weight and c.h. I was shocked, SHOCKED, to find the same .0015 piston to wall recommended clearance.
I dont care, i would not build a forged piston engine under .003. But thats just me, i believe sloppy loose is much better than a little too tight.
You know the expression right? "If you build it too loose, you will know, if you build it too tight, EVERYONE will know".

 

[Cartel]

what I read is the metal has more silicon in it 11%? and the heat expansion has been reduced because of that.
but 30 years ago? they do like reintroducing old stuff as "new tech" so who knows