SICK BOY Posted March 30, 2004 Report Share Posted March 30, 2004 I just did a compression check on my fresh motor,and I have 180 psi.Is that too much to run 93 octane??? Quote Link to comment Share on other sites More sharing options...
Indubitably Posted March 30, 2004 Report Share Posted March 30, 2004 Ya thats too much for pump gas i believe the cut off limit is 160psi. Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted March 30, 2004 Author Report Share Posted March 30, 2004 Do you think a pump/race gas mix is alright?I ran the motor for about a 1/2 hour with 93 in it do you think it hurt anything? Quote Link to comment Share on other sites More sharing options...
fixitrod Posted March 30, 2004 Report Share Posted March 30, 2004 You'll most likely be fine. You can probably pull the plug and look in the cylinder with a flash light. Look to see if the top of the piston looks good or melted. I have heard of builders building 180 psi motors that will run pump gas...not common though. Where did you get the motor work done. That's the person to ask about what fuel to run. If you bought an aftermarket head, ask the company that makes the head. If it's ported, ask the person who ported it. Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted March 30, 2004 Author Report Share Posted March 30, 2004 I built it my self,and the head is from Noss.Dave said I should be able to run pump gas,and the motor is not ported.I had to pull the head off,because the head was leaking and the pistons look as new as they did when I put them in. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted March 30, 2004 Report Share Posted March 30, 2004 Consult with Dave. You may have a bad gauge too. Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted March 30, 2004 Author Report Share Posted March 30, 2004 I'll talk to him,and as for the guage it's a brand ne Mac one that I only used a hand full of times. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted March 30, 2004 Report Share Posted March 30, 2004 What did dave suggest? He really should know the fuel requirements for your banshee being that it's stock ports and his head. I just don't want you to be mis-lead. With 180psi I'd run 110 straight to be on the safe side unless my builder said otherwise. In your case, your builder is Dave since he's the only one who has a modified part on your shee. Did you use some speacial aftermarket piston like the vitos super stock or something. That's high psi. What size domes are you using. Did dave use standard cut domes (shape wise) or did you specify a speacial cut dome. Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted March 30, 2004 Author Report Share Posted March 30, 2004 All my mods are in my sig and yes the piston are Vitos.The domes are standard 21cc domes.Take a look at my sig and see what you think.Thanks for the help. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted March 30, 2004 Report Share Posted March 30, 2004 Sounds like you have a nice set-up. Okay, I have never run vito's pistons but I have heard they give good power. Also, since they are a different shape and seem to be boostin your compression I'd run straight race gas or get a bigger dome. Once again though I think Dave will be able to more accurateley advise. Did he know you had the power pistons when you talked to him? That may be a changing factor. You'd think the compression would go down since they leave the exhaust port open a little longer but your not the only one I've heard that had the compression raise on them. The domes must be taller. That will also change the squish which is why I'd run race gas. Something else you could do is check the squish with pieced of solder and a dial caliper. I'm curious what the number would be. They may be the same with the center of the piston being the only taller part. I need to find some pics of those pistons next to regular pistons. I going go look for some. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted March 30, 2004 Report Share Posted March 30, 2004 Here's pics Meat posted a while back with pics. This is his quote. Hey iv been running the same set of Vito's PowerPistons for 3 years now. Id buy em again, they've stood up to my reliability standards. Here's some pics of a standard Wiseco(left) next to a PowerPiston(right)...... This is where the post resides... http://www.bansheehq.com/forums/index.php?...topic=16733&hl= Sorry I got so off topic here, but I think the pistons are what's causing the non standard compression. The pics here are power pistons...not super stocks Quote Link to comment Share on other sites More sharing options...
Ducman Posted March 30, 2004 Report Share Posted March 30, 2004 You'd think the compression would go down since they leave the exhaust port open a little longer but your not the only one I've heard that had the compression raise on them. The domes must be taller. That will also change the squish which is why I'd run race gas. Fixitrod - Exactly what I thought. Sickboy, I'd check the compression again with a different tester or something to be sure, because with 21cc domes the compresion shouldn't be that high and the power pistons should actually lower the static compression a bit. 180psi is about what you should get with a 20cc dome at sea level. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted March 30, 2004 Report Share Posted March 30, 2004 That is pretty high compression for 21cc domes. I would run at least a 50/50 mix although the money you save over 100% probably won't amount to much particularly with pump gas prices right now. It must be the pistons or thinner base gasket. Checking your squish clearance would probably be a good idea also. Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted March 31, 2004 Author Report Share Posted March 31, 2004 Just to make sure I did my compression test right here is what I did.Screwed gauge in and kicked it intil the gauge wouldn't move any higher,and the motor was cold. Quote Link to comment Share on other sites More sharing options...
Banchetta Posted March 31, 2004 Report Share Posted March 31, 2004 I was told by Vito that the pistons will raise the compression by 10-15 psi.....I'm pretty sure it was the power pistons and not the super stock pistons, but I might have them mixed up....either way, it might be the combo of both.....I agree w/ everyone else,,your playing w/ fire, you might get away w/ it, or you might get burnt....Your call, but I'd run a mix of 50/50 race and 93 octane.... or get larger domes Quote Link to comment Share on other sites More sharing options...
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