Super Jet 701 Melting pistons

[Roseand]

Sorry for so many posts but also keep in mind too much cooling can cause issues. I try to remeber to suggest that all my customers run a temp label on the head. If your running an o ring head with added compression and your head temp isn't at least 110 120 Def F your cylinder is too cold. (Don't forget to check as soon as you stop from a hard run as temp will actually go up for a few minutes after cooling water stops flowing). I control cylinder temp with adjustable pisser. There are other ways though.

Chuck Palmucci
CPT Enterprise LLC
609 510 3062

What's a safe temperature range on the head?

 

[Nuklear6]

What's a safe temperature range on the head?

100-135 I'd say. If your running high compression I'd add a few degrees to both numbers. Adding Compression adds to heat of combustion. Which increases egt and piston temp. If the piston is hotter it grows more which means cylinder temp needs to go up so the sleeves can grow with the pistons. Hence more compession the hotter I'd like to see the head/cylinder temp. Of coarse you can set room temp piston to cylinder wall clearance at a greater number to try and combat this. But my dyno experience shows hp and torque go up with cylinder temp until approx 140-145 and then falls off quickly after that.

 

[Quinc]

At 190psi mine seems to stay between 130-140ish with dual cooling.

 

[Roseand]

At 190psi mine seems to stay between 130-140ish with dual cooling.

I think my ported 180 psi 701 was around that temp as well when I temp gunned it. But after a long high rpm WOT run you don't want to put your hand there for too long even with dual cooling. I personally think my engine would get way too hot with single cooling.

 

[Quinc]

I think my ported 180 psi 701 was around that temp as well when I temp gunned it. But after a long high rpm WOT run you don't want to put your hand there for too long even with dual cooling. I personally think my engine would get way too hot with single cooling.

Even after 60+ seconds at WOT I have never seen it get much more above the low 140's.

 

[Roseand]

Even after 60+ seconds at WOT I have never seen it get much more above the low 140's.

How long can you hold your hand on the head comfortably?

 

[Quinc]

How long can you hold your hand on the head comfortably?

Longer then most people probably could. So I use temp strips, you can get them cheap from McMaster.

 

[kswiatk]

Thanks for all your help and info guys. I will be sending it to Nukleaur6, and i am greatly for his offer to fix the cylinder clearance . His porting has given my engine tons of power. If this above post doesn't show good customer i don't know what does. I would definitely recommend you send your engine work out to him.