Blowm head gasket

[joeyd0730]

sorry for the mispelling, dont know how to edit the title. i have been running my motor with a s-trim, 30lb injectors, stock in tank pump with a external t-rex and a fmu calibrated at 4:1 with 13 deg of timing. i been beating the balls out of it with no problems. it was recomended that i step up to 40lb injectors and get rid of the fmu. so that what i did. took the car for a rip, felt great, then i noticed the oil/water mixture coming out of my breather from the blow by. should i re-install the fmu after replacing the head gaskets? keep in mind my block deck is o-ringed, and have been running 10-12 psi of boost no problems with the original setup. in your opinions what caused this? i did notice a backfire at about 6000 rpm's. i am assuming this is when it popped. thanks in advance joe

 

[2000xp8]

Sounds like you messed with something for no reason. Not sure why everyone loves to ditch the Fmu, but many experts still use it.
Just put it back the way it was.

If anything, i'd look into ditching the t rex and use a 255 pump in tank. But still, check with guys with superchargers or experts before you do that.

 

[Mike92GT]

What mass air are you using? Usually going with larger injectors and no FMU requires a dyno tune / custom chip to get the air fuel ratio right. I would also upgrade the stock in tank pump for a 255 or 190. I run a 255 in-tank along with the T-Rex on mine.

 

[speedytang]

Lets see...Is that timing 13 degrees total timing or base set at the distributor. If that is your base that would be 28 total degrees at WOT with 10psi of boost which would be way to much timing with 93 octane and you did not say if you had something removing timing under boost. Do you have a Fuel Pressure gauge because with with the FMU you would be at 70psi+ @ 10-12psi and no way I can see your fuel pumps keeping up. Now a switch from 30lb injectors to 42lb injectors is a better move and pitching the FMU is a correct method if you have a tuner (PMS,Tweecer,Chip...etc.) I really think your T-Rex could not keep up because you need a 255lph pump. I understand I am asking many questions but 42lb injectors will support 550 rwhp. The backfire was either before the head gasket which was a lean condition probably and if it was after the gasket the water caused the lean pop.

 

[joeyd0730]

i do have a msd boost retard. its set at 1.5. i was using 4:1 calibration with the 30,s and i was getting 70-80 psi undem 12 psi of boost. i agree i am sure the lack of fuel supply was the cause. my fuel pressure regualator has a 1:1 boost refrence. so i guess i will go with a 255, re-install the fmu and set it with a 2:1 boost refrence. live and learn