Cameron Morison
5+ Year Contributor
- 51
- 46
- Nov 12, 2018
-
Christchurch,
New_Zealand
Hi Guys
Im in the process of trying to diagnose whether I am lifting the head, or having head sealing issues on my race motor. So in short, here are some main specs
~ 100mm crank
~ 8.5:1 JE pistons
~ Mitsubishi OEM MLS gasket
~ ARP 12mm head studs
~ Galant VR4 block (same as 1G I think)
~ Evo head (same as 2G I think)
~ Borg S200SXE turbo (makes 16psi by 3000rpm in 5th gear!) Running up to 23psi
~ Kelford TX278 Cams
~ 1.1 Bar pressure cap on coolant reservoir
I think that should be enough of the main specs. I'm logging coolant pressure on the Link, using a honeywell pressure transducer. It does have a pressurized expansion tank rather than the factory recovery bottle style. When I have been hitting boost I see a rise in coolant pressure, more pronounced when the engine has been driven hard for more than half a lap, up to 150kpa, which then settles back down to 100kpa as you sustain load, and when you drop off the throttle it goes back down to 80kpa. There is evidence of mainly air getting pushed out the pressure relief of the radiator cap. This happens at all boost levels but the pressure rise in the cooling system was more pronounced at higher boost.
I have just re-torqued the head studs, put them back to the spec 90ft.lbs and some moved a little more, some went back to original position, the ones that moved more were predominantly on the exhaust side. Then I retorqued them again, up to 95 this time, so 5 over the ARP spec. I havnt had a chance to test it in anger (Cant drive it on the road) but on the hoist against the brakes I was able to get it up on boost and the first couple runs the pressure spiked reasonably high, but I wonder if this was due to having topped up the expansion tank to be brimmed. Then the last couple runs the pressure was much more stable at 100kpa throughout the run.
So really, I'm not sure if I have a pinhole leak somewhere or a head lift issue. There are absolutely no other symptoms of head gasket failure, temps are fantastic. Coolant temps are consistent and low 90's. Its not pushing water but that could be part of the design where there is a head of air on top of the water. On the old system where it ran the recovery bottle it would drop about 50mm from the top level in the system constantly, then stabilize at that level.
Attached files: coolant pressure dsm 1 = pulling onto the main straight at Manfeild
coolant pressure dsm 2 = on the hoist, loading it up as best as I can in 4th gear, after retorque studs
Looking if anyone can share experiences on this topic. where limits were found... solutions etc. Thanks
Im in the process of trying to diagnose whether I am lifting the head, or having head sealing issues on my race motor. So in short, here are some main specs
~ 100mm crank
~ 8.5:1 JE pistons
~ Mitsubishi OEM MLS gasket
~ ARP 12mm head studs
~ Galant VR4 block (same as 1G I think)
~ Evo head (same as 2G I think)
~ Borg S200SXE turbo (makes 16psi by 3000rpm in 5th gear!) Running up to 23psi
~ Kelford TX278 Cams
~ 1.1 Bar pressure cap on coolant reservoir
I think that should be enough of the main specs. I'm logging coolant pressure on the Link, using a honeywell pressure transducer. It does have a pressurized expansion tank rather than the factory recovery bottle style. When I have been hitting boost I see a rise in coolant pressure, more pronounced when the engine has been driven hard for more than half a lap, up to 150kpa, which then settles back down to 100kpa as you sustain load, and when you drop off the throttle it goes back down to 80kpa. There is evidence of mainly air getting pushed out the pressure relief of the radiator cap. This happens at all boost levels but the pressure rise in the cooling system was more pronounced at higher boost.
I have just re-torqued the head studs, put them back to the spec 90ft.lbs and some moved a little more, some went back to original position, the ones that moved more were predominantly on the exhaust side. Then I retorqued them again, up to 95 this time, so 5 over the ARP spec. I havnt had a chance to test it in anger (Cant drive it on the road) but on the hoist against the brakes I was able to get it up on boost and the first couple runs the pressure spiked reasonably high, but I wonder if this was due to having topped up the expansion tank to be brimmed. Then the last couple runs the pressure was much more stable at 100kpa throughout the run.
So really, I'm not sure if I have a pinhole leak somewhere or a head lift issue. There are absolutely no other symptoms of head gasket failure, temps are fantastic. Coolant temps are consistent and low 90's. Its not pushing water but that could be part of the design where there is a head of air on top of the water. On the old system where it ran the recovery bottle it would drop about 50mm from the top level in the system constantly, then stabilize at that level.
Attached files: coolant pressure dsm 1 = pulling onto the main straight at Manfeild
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coolant pressure dsm 2 = on the hoist, loading it up as best as I can in 4th gear, after retorque studs
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Looking if anyone can share experiences on this topic. where limits were found... solutions etc. Thanks