Hi guys!

I have a F20C fully built low comp engine, darton sleeves, CP pistons, rods, ACL bearings, supertech valvetrain, cometic headgasket, ARP headbolts.
I'm running Full-race kit with GT35R, boosting 24psi.

Long story short. Was driving around for the first time with my new setup, trying to do a hard pull on motorway. Fuel cut jumped in as my AEM was set to 35psi (found out from log file). I was wondering what was wrong as I realised that my engine temp were rising quickly from 175 to 210. I immediately slowed down a little and wanted to see if the temps would go down or up. Temps started to rise slowly till 215 and then I pulled aside to check things under the hood. First I thought that it was my coolant lines.

I checked the radiator, and it was almost empty. Then I checked the oil stick, and I noticed that the coolant had mixed with oil for good
I towed the car back to garage, and pulled off the valve cover to discover that the one of the freeze plugs had blew off, allowing coolant to mix with oil. Then I did compression test, and it was showing problems with cyl4. Pulled the head off next, and found traces of knock from cyl4 piston and valves. Cylinder walls were ok.
My theory:

Melted WG lines -> overboost -> ARP headbolts -> head lift -> headgasket damage -> boost in coolant system -> freeze plug off -> coolant in oil -> bad compression in cyl4 because leaking headgasket

So I'm wondering, if overboosting with built and sleeved engine, would I get off just with new headgasket, and headbolts (I'm getting rid of ARP)?
Or do you think that there is definately damage in cyl4 piston or valves or somewhere else. Anyone have experience if there is always or often something else damaged when overboosting so hard. My car has a fuel and ignition map till 33psi.

I wasn't pulling the car hard when I was cruising around, just made couple of halfgas pulls, because I was just testing that everything was working. So no WOT pulls this time God I love this hobby, drove almost 30miles this summer

 

talk to full blown and get the A1 studs....... 35 psi isnt that much off what your already tuned for (33psi) arp will stretch after 26 27 psi...maybe your lucky and all you need is a set of good studs and gasket

 

My ARP's haven't given me any problems at 33-34 psi and around 800 whp.

 

You're trying to fix things that ain't broke, and hence probably overlooking things that are. Get your wastegate lines sorted and your ignition cut out in the AEM set correctly. Then fix your problem with cylinder 4. I suspect it's cracked rings from detonation.

Pull the piston and hope you don't have cylinder damage. If you're lucky, hone, new rings, new head gasket and you're good to go.

Oh, and new freeze plug.

 

Definitely ditch that crappy Cometic HG and go back to the OEM.

 

I'd assume as it's a built motor the decompression is achieved via the pistons and the Cometic is to allow for overbore? Doubt you can get an overbore (more than 0.25mm over) OEM head gasket.

 

Yeah, you might be right; I didn't think of that.

 

What power were you putting down? Was this on e85?

 

I agree with AusS2000, will pull the piston from cyl4, detonation marks can be from the last summer, since we had major problems with former Ecu I had in my car. Didn't open engine during winter. When we dynoed with this new setup, there were no knocking whatsoever when pulling 33psi. So I blame last tuner for the detonation in cyl4

Yes, my cylinder are 89mm, so oem gasket is no option.

I bought FB studs, new gasket, have already spare rings. What do you think, would it work if I use hard brass brakelines for WG lines? Those should hold?

I'm putting down 550hp and 520nm torque, on pump gas 24psi.

 

It really depends where your wastegate lines are running? Are they too close to the manifold, or is the manifold getting too hot (usually due to too much retard rather than detonation).

I run a top mount manifold and the wastegate lines are silicon and don't go over the any exhaust/manifold. Closest they get to it is where they attach to the wastegate. Haven't had a problem with them.