Headgasket Finally Went

[yamahaSHO]

I'd get sure on that timing. If you're listening for pinging, it's too late.

 

[luigisho]

What brand head gasket did you use?

 

[Dirk37]

Could have been machining, I won't really know until I get it apart. I used the shosource OEM gaskets because that's all I could find. Reused the stock head bolts which could potentially have been an issue.

Yamahasho, you might be right about that timing. When I was setting it up, I asked Timothy Tyner what he ran and used those numbers. Never really messed with it after that since I set it up about 2 years ago. The table row in boost is as follows:

Y axis: 110% load
X Axis:
1238 rpm - 9.75
1625 rpm - 14.25
2013 rpm - 19
2400 rpm - 20.5
3200 rpm - 24
4000 rpm - 25.5
5600 rpm - 25.75
6400 rpm - 26.25

The weird thing is that it blew immediately this time whereas before it lasted a long time. I know the knock sensor was there as a backup but maybe that quit working or something. I don't have a datalog of the run so I don't have any way of knowing.

 

[Toolman]

If only you had used head studs...

But seriously, all other things being equal, sounds like your head/deck interface is not perfect. If the same setup worked for some time, no reason it would have mysteriously failed immediately this time.

 

[Dirk37]

I had the heads surfaced so I'm wondering if there's a defect on the block somewhere. I'll have to look when I get it apart. I didn't see one but maybe I didn't look close enough.

 

[yamahaSHO]

That's a good amount of timing and not what I'd call a turbo load timing curve. Care to plot that with RPM and your boost/load curve? Granted Zach has high compression pistons, I don't run that timing on his with E85.

 

[Dirk37]

That's the whole timing setup for in boost. Anything above 110% load (which is around 2 psi) uses those timing values.

I couldn't get an answer from anyone on how they set up timing on these cars so I just did my best to make it work. I wouldn't be surprised if it's too high as I don't really have a feel for what timing values are appropriate.

 

[yamahaSHO]

I understand your timing curve; these cars have very low load based resolution and switch to a WOT timing curve when you WOT. Load is important to lay over with RPM and timing.

As load goes up, timing should go down. As RPM increases, timing goes up... then you balance it out. However, they make a thing you can strap your car to dial this all in.

 

[Dirk37]

Its always been too broken in one way or another to go on a dyno lol. I was going to take it this week since I thought I finally got it all fixed but the car had other plans.

Would you say 20 degrees max is a safe limit for about 10 psi? I really don't want to blow it up again after I fix it this time.

 

[yamahaSHO]

What does your load or boost curve look like?

 

[Dirk37]

Do you mean the y axis of the load tables? I've never heard that term before

 

[Toolman]

I'm running a lot more boost with similar advance. It's not your software that caused this issue, it's the hardware.

 

[Dirk37]

Don't you have low comp pistons? Mine are stock

While I do agree that it's primarily some sort of mechanical issue rather than the tune, too much timing won't help the situation.

 

[yamahaSHO]

Peak torque timing of 20+ degrees at 3-4K RPM isn't going to help cylinder pressures.

If you graph out load or boost vs RPM, you should get something like this:

 

[Dirk37]

Oh ok I'll see if I have any good datalogs

 

[Dirk37]

Here's the best I could find

 

[Shamwow]

Perhaps the head or block is cracked?

Doing this same job on the twin turbo MetSHO right now. Hope my luck is better than yours..

 

[shopartsnw]

Call ARP. The studs and nuts should be about $8.....cheaper if we can get them to sell as a set.

If ShoSource would call ARP(ask to speak to Ron Fruchy's),we could get them to package Both crank bolts,head bolts,head studs,intake bolts,and just about any other bolt needed on the SHO. Just like I told y'all about Cometic will make gaskets without a setup/drafting charge,ARP will do the same.

A head bolt has all its torque on the threads of the block.

A head stud screws hand tight into the block and when a nut is torqued down,it's pulling on both the threads in the block AND the threads on the head stud(X and Y axis).

Do a google search and you'll find many pages describing the advantage of studs.

And like I said,Allen head head bolts=cheapest bolt the manufacturer can find

I will call and talk to Ron and see if we can swing a better price or make them a package. Like Matt said, every other time we tried, it was super expensive, but I am up for another try, and it seems like there might be enough people who want them for us to buy in bulk.

I will update the thread and the SHO Source site once I get more information.

Thanks for the contact name.

Mike
SHO Source

 

[Dirk37]

I'd be very interested if you guys could just get an ARP head stud kit together.

 

[Dirk37]

Did a compression test tonight, same cylinder as last time that failed. Must be a defect on the block or that cylinder is running lean and pinging.