Part IV of my build can be found here: https://www.theturboforums.com/smf/index.php?topic=43105.0


Well, I am pressurizing the coolant once again. I have not heard any detonation.

I started pressurizing the coolant while running 10-13 PSI while slowly adding timing (never got over 5* pulled from base map in boosted region) and pulling fuel to compensate for the Alky Injection. However, the timing was still less than 18* total and my AFR was below 12:1.

While doing more research I found an excellent technical resource that covers the low level details of how compression, quench, ignition timing, combustion chamber design, rpm, flame front velocity, detonation, and etc all interrelate.

One very interesting detail was that due to the increased combustion chamber charge velocity at higher rpms causing increased turbulence in the combustion chamber timing should actually be retarded at higher RPMs due to the increase burn rate caused by the increase in turbulence.

This is exactly opposite to how my tune is setup. Mine adds timing as the RPMs increase. This is the tune that came with my AEM; however, I am very curious what other methodologies people use for setting up timing vs RPM.

The tune that came with my AEM seems to have a linear 0.64* retard per PSI.

I have now obtained a set of 0.065'' Cometic HG, which will be going on in place of the 0.020'' copper shim and Felpro 8548s.

I will likely start to pull the heads off tonight to determine where the failure occured see if any useful information can be determined.er

If after changing to Cometics and double checking my tune I have another HG issue, I will have to replace my E7s and ported stock intake for some decent Aluminum pieces in hopes of retifying my HG issues.

Here are my current IgnitionTiming vs RPM for a few different boost levels:

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The retarded timing as the engine passes torque peak is common practice for me. I don't go over about 24* ever (once in boost). If the boost is over 14 psi - no more than 22*. I've never had a headgasket problem to speak of since I started this. I run as much as 36* before 3500 to help the car get on the converter quicker. After this it drops like a rock. Your numbers seem safe enough - although I'd prefer a bit richer if it were my car especially if you are seeing these numbers on a chassis dyno.

 

When I said AFR less than 12:1, this was on a 4th gear pull on the street. For the most part, it was less than 11.5:1 and only very briefly came in the neighborhood of 12:1.

Turbostang, could you post your timing vs rpm and boost values so I can get a feel for the shape of your curve?

Thanks

 

wow that sounded a bit wierd.. LOL.

I have FAST and I'd have to see if I still have my old log files - which I am sure I do - but not on this PC. I'll check it out tomorrow.

 

may have something to do with the e7s

 

Turbostang

<Mr Burns> Excellent </Mr Burns>



Request:
If you are going to be digging into your tune or log files, would it be possible for you to dump your entire timing table into a post so I stick it into Excel and analyze it? :rock:

You seem to have a better grip on what works. I sure am becoming experienced at what doesn't work. LOL

 

Welcome to E7 hell. I never could get mine to hold boost. I do hope you get it sorted ot though. Good luck.

 

Turbostang

Can you please post your timing info? Thanks

I haven't started to tear the car down yet due to it being too wet to move it into my shop...

But soon the autopsy will begin.

 

Well I looked at it and forgot to post.. but I didn't see a way to get the table exported to a spread sheet.. If someone knows.. tell me how and I'll do it.. It is FAST.

 

If it not a head gasket you could be lifting your heads.

 

look at your pistons and spark plugs carefully. Make sure it's not a clogged injector leaning out one cylinder. while stock E7's are a crap shoot when it come to headgasket retention (and i've had my share of blown headgaskets with them) my latest combo has stock heads that are ported and have .040" cut off the deck (so they are even thinner than stock) and increased compression.

my latest dyno session went like this:

22* total timing (locked out)
100 LL fuel
alky kit (of my own poor design)
14psi of boost
NO intercooler

the car has been abused and still no gasket trouble. So with your conservative timing and the fact that you run alky I would look other places besides your tune.

 

Dman, do you run studs? And if so, what torque specs?

Thanks

 

i'm running an old set of ARP bolts that have been on and off atleast 4 times over the last 6 years. long bolts torqued to 95, short to 85

 

No fair. You guys and your head gasket retaining E7s... I had no such luck.

 

ARP Studs. 95 ft-lbs top, 85 ft-lbs bottom. Lower intake to 18 ft-lbs.

 

trust me i've had my share of problems with E7's. But on this combo i've been very careful with timing and fuel (even though I pressed my 30# injectors to 459rwhp ) if you are blowing headgaskets with 18* total then you are either running way to much boost or there is another problem somewhere.

 

Spark Plugs:

They had been run a few minutes since the last boosted run.

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Here was my problem....

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Well, I have everything apart now.

I do plan on making a few changes while it is apart.

I will be installing 0.065'' Cometic head gaskets. Does anyone know if it is best to use Copper spray or not with these? It seems everyone has a different opinion?!?

I also have header wrap to try to reduce my engine bay temps (not that I was having issues, but less heat = good).

I need to order another set of ARP head studs as well. I almost stripped one out on the top allen fittings today, which would have been a major bitch. Definately don't want to risk that happening again.

Perhaps I can have it back together in a week.

Things are about to get crazy for me. I am starting a new job in the next few weeks and have to move about 500 miles away. So I doubt I will have much of a chance to work on my car in the next several months.

I will be moving to the Columbus, OH area if anyone is from those parts....

If anyone knows of a house with a nice workshop for sale, I am in the market...

Damn, housing costs alot up north...grumbles...

 

Looks like the heads are lifting to me. Pressure pushing right past the fire rings into the coolant passage. My gaskets looked like that across the top of all 8 cylinders. Looks like #1 was doing the same thing, just not as much.