Resolved ARP L19 Head Studs

[llxkevinxll]

Hello all,

I have noticed my car is consuming coolant since switching to the Hx35 / E85 setup. Others have mentioned they see a spray from under the passenger side during a pull, my coolant overflow is on the passenger side of the car. Initially I assumed it was a head gasket issue. This past winter I swapped to an HKS hg and inspected the block and head for cracks or damage, no issues. Even the old MLS gasket looked fine. I am still consuming coolant, though it appears to be at a lower rate than before. I am using standard ARP studs torqued to ARPs specification. The issue appears to be more prevalent when running E in the tank. Peak timing is 15 on E compared to 5 on pump 93. This motor compression tests in the 210-220 per cylinder range. The holset is being run at roughly 32 psi peak. My assumption is the new cylinder pressure maximum on the E85 tune is lifting the head. From all of your experiences, are the L19s a worthy upgrade? Did you notice real clamping differences? My car only made 448whp on a mustang dyno which seems to be below the normal level people recommend the L19s but the compression on this motor is relatively high. The 6 bolt L19s are not inexpensive so before making a purchase decision I was hoping to see what others had to say.

Thanks for the help,
Kevin

 

[1990TSIAWDTALON]

I ran my Red Talon at 40+lbs of boost on E. I have L19's and they are torqued to 115 ft/lbs. Yes that is a lot and it is my personal value, not everyone's. I have not lifted a head with them at that torque. I even torque regular ARP's down real good. All custom specs though, not from ARP or the FSM.

 

[EC17PSE]

I cant exactly help out here but i have bought L19's for my upgrade. I just wanted piece of mind more then anything. I might also redo the threads in the block so they are stronger and do about 100ft/lbs instead of the 90 they spec

 

[Zack Huffman]

What ballpark compression ratio are you at? With 210-220psi, I'm guessing you are around 9.5 :1 ? That much static plus 32psi of boost and the extra fuel volume on E, I'm not really surprised that it pushes some coolant. The L19s will help, but the decks still need to be smoother than a baby's ass for your gasket to hold up. Your power numbers are just numbers, but I'd expect a nice jump upward once you get this issue fixed. Mustangs read low, 448 mustang if then taken to a dynojet would be well over 500. I say pull the trigger and go L19. I would agree that your high CR is probably the biggest contributor to you lifting the head.

 

[llxkevinxll]

Thanks for all the replies guys. Seems like L19 is worth the cost and may actually help me. I'll go that route and see what happens.

 

[1990TSIAWDTALON]

Just for the thread info, I noticed the high compression numbers also and figured you were a 10:1 motor which is what my Red Talons motor is and I dry test out at 200 psi.
Like Zack said, you need a mirror surface to get any MLS to mate up and seal correctly.

 

[llxkevinxll]

Just for the thread info, I noticed the high compression numbers also and figured you were a 10:1 motor which is what my Red Talons motor is and I dry test out at 200 psi.
Like Zack said, you need a mirror surface to get any MLS to mate up and seal correctly.

My car is ~9.65:1 with the HKS 1.3mm gasket. The compression test was done when I had a 1.0mm gasket which resulted in 9.8:1. The head and block were both decked and prepped for the original MLS roughly 5k miles ago when the motor was first assembled. The head was off the car this past winter and inspected by the machinist. I used a straight edge on the block, which isn't supremely empirical but it's flatness seemed satisfactory. I appreciate the input, I'll be sure to make sure the mating surfaces are as they should be when reassembling with the L19's.