I have been fighting a problem all year.
First, I know it is not optimal, but my radiator cap is slightly lower in the car than where the upper rad hose comes out of the intake manifold (around 2" lower), but still higher than the heads and intake manifold, just the 90deg hose out of the manifold is higher. I was originally running a 16psi rad cap. I would fill the rad up with water, turn electric water pump on to bleed air and top up.
Then when I run the car at the track, 1/8 mile drag racing, at around 500ft, it pushes water out, fills up the overflow 1 liter can and sprays water out when overflow full. Empty overflow can, make another run and same thing happens. 3rd run is fine cause there is so much water missing in rad/engine. If I re-add water, same issue. Not sure if it matters, but overflow can is lower than top of rad.
I switched to a 20psi rad cap and installed 0-30psi pressure sensor I had at the shop to monitor coolant pressure. Nothing changed, same exact thing happens. I looked at data and can clearly see that the rad cap opened at 16-17psi and it was a very slow climb to 16-17psi, so no signs of compression leaking in coolant system which I thought was the issue. Rad cap opens, pushes water out around 500ft, closes back up and all good for rest of the run. I should add that engine never gets over 175-180deg of coolant temp and most runs is around 160deg.
I don't want to run the engine/rad low enough with water to prevent this since it will pretty much not have much water in the heads.
Any idea what the issue could be? Do I need a higher psi rad cap? Do I need to install a remote rad cap at the highest point of the coolant system? Is it compression leaking in even though it is slow rise to 16-17psi?
It is not pulling the water back in when engine gets cold, but it is an overflow can and not an expansion one, so I guess that makes sense.
This is on a SBC with an F1X on methanol currently running 22-24psi of boost if that makes any difference.
Thanks in advance. I am at a lost!!
First, I know it is not optimal, but my radiator cap is slightly lower in the car than where the upper rad hose comes out of the intake manifold (around 2" lower), but still higher than the heads and intake manifold, just the 90deg hose out of the manifold is higher. I was originally running a 16psi rad cap. I would fill the rad up with water, turn electric water pump on to bleed air and top up.
Then when I run the car at the track, 1/8 mile drag racing, at around 500ft, it pushes water out, fills up the overflow 1 liter can and sprays water out when overflow full. Empty overflow can, make another run and same thing happens. 3rd run is fine cause there is so much water missing in rad/engine. If I re-add water, same issue. Not sure if it matters, but overflow can is lower than top of rad.
I switched to a 20psi rad cap and installed 0-30psi pressure sensor I had at the shop to monitor coolant pressure. Nothing changed, same exact thing happens. I looked at data and can clearly see that the rad cap opened at 16-17psi and it was a very slow climb to 16-17psi, so no signs of compression leaking in coolant system which I thought was the issue. Rad cap opens, pushes water out around 500ft, closes back up and all good for rest of the run. I should add that engine never gets over 175-180deg of coolant temp and most runs is around 160deg.
I don't want to run the engine/rad low enough with water to prevent this since it will pretty much not have much water in the heads.
Any idea what the issue could be? Do I need a higher psi rad cap? Do I need to install a remote rad cap at the highest point of the coolant system? Is it compression leaking in even though it is slow rise to 16-17psi?
It is not pulling the water back in when engine gets cold, but it is an overflow can and not an expansion one, so I guess that makes sense.
This is on a SBC with an F1X on methanol currently running 22-24psi of boost if that makes any difference.
Thanks in advance. I am at a lost!!
