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Blow headgasket msq and datalog review


s30kid

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Hello everyone I was hoping for some insight on my tune for my car. I though I had set it up to be very conservative, running rich under boost with low timing, however I have blown another headgasket.

 

I had a date set to get the car tuned but that turned into a huge fiasco with the tuner taking my car for over a week and completely blowing me off resulting in some heated conversations. Long story short I took the car back and had to fully retune the car because it ran worse then when i brought it to him. I got the car running great on 5psi of boost daily for a few months. afrs were 11s under boost 14-15s crusing on the freeway. The problem is I got greedy and set the EBC to 11psi which was a load of fun car was running great for about 3 days, never skipped a beat. Never leaned out. But alas, all good things must come to an end and the head gasket failed.

 

My engine setup consists of:

f54 block

replacement cast turbo pistons

replacement turbo rings gapped to .020 on the top and .022 on the second ring

balanced rotating assembly

n47 head 

A stamped cam

fidanza 11lb flywheel

6 puc clutch

holset HY35 turbo

tial 38mm wastegate with 5lb spring

440cc supra injectors

fuellab pressure regulator at 40psi at idle

walbro 255 fuel pump

rb25 throttle body with s13 tps

methanol injecton but not currently spraying

megasquirt 2 with direct coil control, launch control, boost control 

arp head studs

felpro headgasket

gm clt sensor

gm intake sensor (but i think the methanol ruined the sensor because it no longer reads)

 

also I have a 2 1/2 crush bent exhaust through a baffled muffler to keep the car quiet so yes there is back pressure

 

I think thats everything.

I have many datalogs unfortunatly i was not loging when the head gasket blew.

however the gasket blew in 3rd gear full throttle 11lbs of boost around 4500rpm. I saw the wastegate dump tube  throw a fireball up and over the car and I saw it land on the ground behind me. I believe that was a piece of headgasket.  

 

I dont have any datalogs of when the car was running 5 psi but I do have 5 datalogs of when I was setting the boost controller for 11 psi.

 

I had to compress the files into a .rar file because I do not have the correct permissions to upload .msq or .zip 

 

Thanks for the help, it is greatly appreciated!

Samuel msq and datalogs.rar

Edited by s30kid
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The compression is around 8.3:1 with the n47 head with 10cc dished pistons. I do plan on getting a knock sensor and I forgot to mention I do plan on getting a dyno tune once I replace the gasket. As well as rejecting the methanol. I'm waiting on a new nozzle the one I have is too big right now and bogs the motor down. I think it's like a 600hp nozzle. Sorry for the fast reply I'm at work right now

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How is your fuel pump mounted and how much gas did you have in the tank?  I had issues of leaning out when my tank would get low due to my walbro not being able to pull enough fuel.  I found it by adding a fuel pressure sensor and logging it.  

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 I saw the wastegate dump tube  throw a fireball up and over the car and I saw it land on the ground behind me. I believe that was a piece of headgasket.  

 

Am I the only one who is confused by this statement?  Are you saying that you think a piece of the headgasket came out of the wastegate dump tube on fire?  Is your dump tube pointing up?

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Yes the wastegate tube dumps straight out the hood sorry for the confusion. And I did a little work on the car yesterday. Compression test with 150 across the board. Number 6 is where the gasket has blown however it's a small pinhole. And by that I mean the car isn't blowing smoke and consuming all the water and overheating like usual. It's just slowly sipping the coolant. I actually drove the car all day yetlsterday and only had to top off the radiator once. Also I retract my statment about the headgasket going through the exhaust I actually believe it was the exhaust manifold gasket that got burned up because yesterday it did it again and I had a huge exhaust leak afterwards. Anyway this weekend I will be pulling the head and sending it to the machine shop.

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Yes, so I got around to working on the car this weekend and it turns out the bolts holding the number 6 runner backed out and caused the gasket to burn up. I already have a new exhaust and head gasket. The head looks good. It has some grooves from the firing ring of the gasket and that's why I'm machining it. Thoes grooves were there the last time I popped the headgasket but I just didn't have enough time to get the head done. My machines that says it's very common to see that and it's caused by the head slightly lifting and smacking back down on the gasket. So I read up on another forum and I'll be tourquing the head to 70ftlbs instead of the arp recommended 60ftlbs. I had this head fully rebuilt 6 or so months ago so I'm glad to see everything is good. The cam has worn in good, all the rockers and valves still look good. So just a resurface and I'll be ready to put it back together

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I forgot to mention the car runs on 91oct pump gas. I have a 16 gallon fuel cell with a 2 inch sump on the back but no sponge. The fuel pump is mounted horizontal to the bar that holds the rear of the control arms. The pump is mounted lower then the output of the tank for gravity feeding. And there is a Russell -6 filter between the tank and the pump. I want to say I had 3/4 of a tank of gas but I'm not sure. But that was a great point you made Namor, I will add a fuel pressure sensor to the megasquirt that way I can check in the future. The fuel pump location has always bothered me and I'd like to go to a internal pump swirl pot setup with a scavenge pump feeding the pot. And to answer Madkaw, I've just always had a n47 head. I tried many times to buy a p90 but they are harder to find than a diamond in the backyard. I actually found one. There was a 280zxt at my local yard and I was the first one to the car. Paid 60$ for a p90 with a non turbo cam, 6 cracks and warped beyond saving. So I stuck with the n47. And I enjoy the higher compression. The car makes a ton of torque, has great low end power and spins 225 60 15 tires through 4th gear on 15 psI. Also, there is a guy here local that has a turbo z with a gt35r, and a far better tune than i, and my car blows him out the water and dragges him behind my bumper with a 30 foot rope. And mines a 2+2! I've done some research and if you clean up the bowls on the intake side and clean up the castings the head should flow the same as a stock p90. Anyway this post is much longer then I originally Intended it to be. Thank you guys for the input and let me know what you think

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Are you using a turbo distributor? Make sure your timing is matching what ms says it should be. Ms is funny with timing control. It needs a very tight trigger angle range. You may get it to run fine with say 25 degrees trigger angle but then it may be advancing timing when it should be retarding and vice versa.

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Yes I run a turbo dizzy and the last time I checked the trigger offset it was spot on but I will double check when I put it all back together. Thanks for the tip Chickenman I Will try that out. Normally I use red hi-temp rtv but This time I was using all brand new gaskets so I didnt use any. Also I normally run the car straight pipped so when I closed the exhaust cutout I think all the back pressure in the exhaust caused the exhaust gasket to fail.

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