13.5 : 1 JE piston and winter riding?

[jaysrippen]

I do alot of winter riding (heavy long pulls in cold temps) and was wondering if the high comp 13.5:1 JE piston would be an issue? I'm running good 93 octane fuel with stock engine/exhaust. thanks ?

[ShadyatBest]

you might have to bump up the octane. The cold thick air+higher octane+high compresion= mad tourqe

[jjgixxer]

93 will be fine.. Just jet for cold weather when it comes.

[jjgixxer]

you might have to bump up the octane. The cold thick air+higher octane+high compresion= mad tourqe

oh also you mean thin air since the molecules are closer together .. ?

[jaysrippen]

ok, I was just concerned about cold weather and 93 octane with the high comp piston. I will jet up though when winter comes.

[Wiseone]

Why would you want to run so much comp with a stock Cam?

[Shawn_Mc]

Why would you want to run so much comp with a stock Cam?

The stock cams are actually more radical than some of the big HP cams...they respond well to higher C/R's

[Wiseone]

The stock cams are actually more radical than some of the big HP cams...they respond well to higher C/R's

I would agree the stock cam is a bit agresive and would work well with more

CR I would have to disagree based on experience that the stock cam would work well or at all with 13:5-1.

The only occasion that I have had Honda 450 a piston split across the top was at LLynn's last week with a +35 racer who was running a 13:5-1 with a stock cam. The split pistons showed some heat. A hardness test was performed and both had turned to butter from excessive heat. I also haven't seen two 450 cylinder heads CC the same.you could be as high as 13:8-1 or more. I would bet the only power gain is the frsh top end and would actually be a HP/Torque loss on a dyno.

BTW I supply the Honda 450 race pistons to, #32 Ryan Clark, #686 Josh DeMuth, # 17 Robby Reynard, #31 Jason Thomas, #48 Jeff Gibson, #44 Justin Bucklew, #198 Jacob Saylor(StLouis Hole shot), Eric Velajo #144 Kyle Partridge, all are racing with a 12:5-1.

Other colored bikes supplied, #56 Josh Woods, #156 Willie Browning, #84 Berry Carsten, #12 David Vullemin (13:5-1 at altitude in Colorado).#38 Jeff Dement, # 52 Shaun Hamblin, #350 Shawn Skinner, # 3 Mike Brown.

[therapture]

oh also you mean thin air since the molecules are closer together .. ?

No he's right

Cold = more molecules in a given volume of air = "thicker" the caveat with this is the humidity, even in colder conditions, if you have high humidity, you may not need as larger a main as you would think. Now when it is so cold that the water is frozen out of the air, the humidity is WAY LOW and you can increase jetting considerably to take advantage of the extra oxygen in the dense air. But, then you have to take the altitude into account...

Jetting can get complicated LOL

[jjgixxer]

No he's right ?

Cold = more molecules in a given volume of air = "thicker"

hmm guess I need too go back too science class.. Must of been the part I sleept thru .

[therapture]

hmm guess I need too go back too science class.. Must of been the part I sleept thru . ?

Tell me about it, I think sometimes I slept through part of my life hahah...

[jaysrippen]

Is that the genaral concensses??? that 13.5:1 is to high and actualy a possible power loss and high temp issue? I'm at 2000-2400'. thanks guys for the replys!

[jaysrippen]

Just a quick one as well: What are the signs of detionation on a 450? Pinging sound?