Ok, after blowing my SECOND head gasket due to detonation, timing advice PLEASE

[ktm]

I can't afford to blow a third gasket in as many weeks. I thought my timing was not that aggressive until I took a look at my map again and saw I was at 28 degrees at 10 psi, but 20 degrees at 15 psi. I still detonated #5 clean out the side of the head and removed a 1 inch long piece of gasket!

 

Below are my old timing map (which I blew the HG on) and my new map that I am working on.

[Thumper]

I can't afford to blow a third gasket in as many weeks. I thought my timing was not that aggressive until I took a look at my map again and saw I was at 28 degrees at 10 psi, but 20 degrees at 15 psi. I still detonated #5 clean out the side of the head and removed a 1 inch long piece of gasket!

 

Below are my old timing map (which I blew the HG on) and my new map that I am working on.

 

What type of gasket are you running? Head bolts?

[Forrest]

What's your static compression ratio?

[BRAAP]

Bo, just curious, what boost level corresponds to what percentage of load, i.e. what Load percentage is atmospheric pressure, 10 PSI, 15 PSI, etc?

[Bernardd]

Methanol injection is where it's at. Run 28deg's at 15psi and buy a couple of extra tires for the back. I think Afshin has a setup lying around that he'll never use. *poke*

[1 fast z]

I run 28 degrees timing at 15 lbs of boost and 22 at 25 lbs of boost. I have a 8.3 CR, and a pretty good chamber design. What head is this? Piston to head clearence?

 

That has a BIG part of the detonation resistance issue.

 

Have you verified that what your map says timing is, is the same thing as what your timing light says?

[ktm]

1 fast z, I verified that during my original installation, but I plan on verifying it again after I install the new head gasket.

 

This is a P90A head, simple rebuild, no porting, running a stock turbo head gasket (the last two that blew) on an F54 block and dished pistons. Compression should be 7.4:1. I am using ARP studs torqued to 60 ft-lbs.

 

Paul, I knew I forgot my load information and I can not access Hybridz from work anymore for some reason.

 

Following are my load correlations, the top number is psi and the bottom number is the load band in percentage.

 

-12.0 -9.2 -6.4 -3.3 -0.5 2.2 5.0 7.8 10.5 13.3 16.0 19.2 21.9 24.7 27.5

7 14 21 29 36 43 50 57 64 71 78 86 93 100 107

 

So 50% load is 5 psi, 64% load is 10.5 psi, 71% load is 13.3 psi, and 78% load is 78 psi. I am still pulling vacuum up to 36% load. In theory I should not see more than 78%. Wolf interpolates between load bands based on the MAP.

[TimZ]

Have you verified that what your map says timing is, is the same thing as what your timing light says?

 

...and have you verified that the TDC mark on the damper actually comes up at TDC? The timing light will only tell you how you are aligned to the damper.

 

Also probably a dumb question, but since nobody has asked it yet, are you sure that the block deck and the head are both flat? Surface prep looks good around #5?

[ktm]

Yep, surface prep is good around around #5. If you look at Cygnus' Good example of a blown HG thread, you'll see he detonated on 4, 5, and 6. I detonated on 4, 5, and 6 as well, with #5 blowing out similar to his.

 

Yes, TDC on the dampner is coming up as TDC. I just reverified this yesterday when I pulled the head.

 

I am thinking that my timing at 15 psi is ok, I was just detonating on the way up to 15 psi. I don't hit 15 psi all that often, usually hitting 10 psi or so quite frequently. My timing at 10 psi was a little aggressive in retrospect.

[MJLamberson]

I should probably keep my mouth shut when I dont know what Im talking about but would useing high octane fuel help?

[ktm]

Higher octane fuel would definitely help, the only problem is availability. I know places to buy 100 and 104 unleaded around where I live and work, but it makes it rather inconvienent if you are tuned for higher octane and then have to use straight pump gas.

[TrumpetRhapsody]

dual maps, dial boost down on the low octane map? That's what i'm planning to do. I guess you'd have to have a laptop handy tho

[510six]

Higher octane fuel would definitely help, the only problem is availability. I know places to buy 100 and 104 unleaded around where I live and work, but it makes it rather inconvienent if you are tuned for higher octane and then have to use straight pump gas.[/quote

 

 

What are your A/F ratios up to 10psi of boost , My suggestion would be to run 11.7 -11.6 while under boost and if your Wolf can use the factory knock sensor I would do so. I couldn`t agree more with Bernard about the methanol injection especially as you have the ability to compensate for the extra fuel with your Wolf EMS. As far as the timing goes a conservative approach is best esp. with pump gas.My knock sensor cut timing after I picked up a BAD load of 91 oct. pump gas about two weeks ago.

[myplasticegg]

http://somender-singh.com/content/view/7/31/

[Thumper]

I blew out my stock turbo head gasket at 18psi then replaced it with a metal headgasket. Usually a blown headgasket is from detonation but it can also be from head lifting and being pushed out. A metal resists this alot better. With the same tune as the 18psi blow-out I was able to run 23psi no problem (except with the trannies)

[clint78z]

I would get an injector cleaning and volume test done. The timing sounds conservative, yes reverify timing with a light. Make sure your distributor or igntion pickup is locked down properly, and there aren't any electrical noise to skew timing.

[Clifton]

That's not that much timing. I run 20*at 18 psi on 91 octane on my L28, P90/dished. For you to go through 3 gaskets, I think you have another problem. Even 7M's with the there HG problems don't blow them from detonation. A piston will go first unless it's forged. They will blow even on n/a but it takes some time. I have never blown a hg from detonation, even on L's and I have broke many pistons on various engines.

 

If you aren't popping them from deto and it's a sealing problem H20 inj won't help as the cylinder pressure would be the same. I would check for straightness and get a MLS gasket.

[z-ya]

Have you verified your timing with a timing light? At idle, check your timing in the Wolf, it should match what you measure with a timing light. If it doesn't, you can program a timing offset into the Wolf so that you timing table entries match your actual measure timing. It sounds like your actual timing is advance from your timing table. You should be able to run 25deg all day at 15psi with a stock L28ET long block.

[ktm]

Pete, Clifton, that is what I intend to do once I get everythign bolted back up. When I first installed the engine, I verified that my timing was correct between Wolf and the engine. I will reverify once it's back together.

[proxlamus©]

i blew my gasket on cylinder 5 lol. hmmm seeing a trend going on...