s30kid Posted March 7, 2015 Share Posted March 7, 2015 Alright guys Ive got an interesting question to ask. Can 15psi of boost be the reason why I blew my head gasket? First off my setup was like this: Fully rebuilt in november of 2014 F54 block, stock rotating assembly n47 head, liners removed, exhaust ported and polished, polished combustion chambers and new valvetrain 440 cc supra injectors stock 83 turbo 2.5" downpipe ported intake manifold and 60mm throttle body megasquirt 2 3.57 mishimoto 3" fmic 2.5" IC piping greddy blow off valve STOCK HEAD BOLTS. I was not low on coolant and my water pump is still good. I was running 10 psi for about a month and the car ran great never had any problems so I increased it to 15psi and for 2 days the car was amazing. Smoked corvettes and camaros All day! I decided to go out for a drive-n-tune. As I was entering the freeway I ran the car 1st-4th on 15psi shifting around 5500. once I let out of the gas the car was stumbling all over itself and so I limped it to a friends house where we tore the car apart and found the blown head gasket and ultimately the cracked head. I believe there are 2 reasons as to why I blew the geadgasket. 1.) The head gasket itself was cheap and came in a "full gasket and rebuild" kit. 2.) I reused the stock headbolts during the rebuild. So I think that with that much boost the head was floating and eventualy blew out. Im wondering what all of you guys think and will it happen again? Now im running a stock n47 head with a felpro head gasket and ARP Head studs Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted March 7, 2015 Share Posted March 7, 2015 Many L28 setups will ping/detonate if run at high rpms on the highway that wouldn't even when thrashed in "around town driving". Quote Link to comment Share on other sites More sharing options...
flatrate Posted March 7, 2015 Share Posted March 7, 2015 make sure its not pinging or suffering from any detonation, that will destroy a head gasket quickly, among other things. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted March 7, 2015 Share Posted March 7, 2015 How much timing are you timing while on boost?Should be no more than 20-24 btdc.Make sure your fuel pressure stays up.The head studs are worth the money.Some people say fel-pro gaskits are not good by I never had any problems with them.Check the top of the block and the head with a straight edge.I have heard that taking the liners out of a n47 head really doesnt do anything.I would find a n42 head if you want to do some porting.I have had many problems caused by old nissan head bolts.If thay have any rust pits in them I throw them away. Quote Link to comment Share on other sites More sharing options...
s30kid Posted March 7, 2015 Author Share Posted March 7, 2015 If you port the n47 correctly it flows amazing. You loose low end torque but with a trubo you gain high rpm power. I don't have dyno sheets to prove it. I'm just going off of how far the car pushes me into the seat. Anyway. The timing. Im running stock ignition for now because my megasquirt was having issues with the ignition. Locked the mechanical advance and set the timing to around 20. Quote Link to comment Share on other sites More sharing options...
s30kid Posted March 7, 2015 Author Share Posted March 7, 2015 20 degrees at idle Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 8, 2015 Share Posted March 8, 2015 You detonated and blew your head gasket. You ran lean and detonated, specifically. It has nothing to do with your head bolts nor the head gasket. This is covered extensively during Christmas break, if you search. Quote Link to comment Share on other sites More sharing options...
TimZ Posted March 9, 2015 Share Posted March 9, 2015 You detonated and blew your head gasket. You ran lean and detonated, specifically. It has nothing to do with your head bolts nor the head gasket. This is covered extensively during Christmas break, if you search. Here: http://forums.hybridz.org/topic/120739-zcar-source-head-gasket-limitation/?hl=%2Bhead+%2Bgasket did a search for "head gasket" in this forum - nothing tricky. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted March 9, 2015 Share Posted March 9, 2015 (edited) You leaned out, as they have said above. The question is if this was a lean spike you hit or if you were just running lean the whole time and it was just a matter of time. Did you have the lean protection on in megasquirt? Did you have fuel cut set for the boost controller with a maximum kpa threshold? Adequate fuel pressure? Adequate fuel? Did you adjust your map after you bumped up the boost? How was your AFR? Do you have your data log of the incident? Do you have your current tune? If you just move to a metal head gasket and studs, you will end up blowing the motor again, but now you've removed the relief valve of the head gasket, probably with a cracked block or head, or piston damage. It is extra insurance, but you need to make sure the problem is gone before you go implementing that insurance. Edited March 9, 2015 by seattlejester Quote Link to comment Share on other sites More sharing options...
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