Blown head gasket questions

[michael evans]

Trying to find answers why I have gone through so many head gaskets (4). Had it dyno tuned and it made 543 HP and 704 FT on a easy tune. It will easily handle 30 pounds of boost with no timing retard but only run 24 pounds.

In my case the engine management system is a XFI and the injector duty cycle did not increase.


Have a few questions does thickness of the head gasket on a 109 block have anything to do with it's lifespan ?

Should the head bolt torque be adjusted with the thickness of the gasket ?

Is it mostly the case that #1 and / or #2 cylinders are the first part (s) that let go (go lean) ?


Each time I have made changes to the system trying to figure out why it is getting lean on the top end.

This time getting rid of the factory fuel lines and adding bigger injectors.

 

[Mr.Spool]

Have a few questions does thickness of the head gasket on a 109 block have anything to do with it's lifespan ?

no

 

[Mr.Spool]

Is it mostly the case that #1 and / or #2 cylinders are the first part (s) that let go (go lean) ?

no

 

[Mr.Spool]

Each time I have made changes to the system trying to figure out why it is getting lean on the top end.

i will offer you this,one can only tune to their leanest cylinder.

 

[Mr.Spool]

Each time I have made changes to the system trying to figure out why it is getting lean on the top end.

fuel pressure,and the right afr targets and timing with the proper octane is the way

 

[Mr.Spool]

In my case the engine management system is a XFI and the injector duty cycle did not increase.

if you want to pm me the the combo and fuel and tune i will look at it.

 

[Mr.Spool]

Trying to find answers why I have gone through so many head gaskets (4)

thats rough

 

[michael evans]

thats rough

I know it is like asking what is the best oil to use ?

 

[TexasT]

Is it the same cylinder pushing the gasket out each time?
I would have to think the gasket is doing the job of fuse and letting loose before worse things happen.
Unless you have the O2 on each cylinder it is pretty hard to tell what is happening. One can be lean while the rest are fine. This might be seen with alky injection with it up stream and the distribution not really working out.
Best to fuel with the injectors and use the alky to cool the charge. Once you get to where the engine "needs" the alky for fuel it tends to have problems .

Also you mention bolts. Is there a reason you don't use studs?

 

[Mr.Spool]

This might be seen with alky injection with it up stream and the distribution not really working out.

its not a distribution problem.

 

[Mr.Spool]

Trying to find answers why I have gone through so many head gaskets (4). Had it dyno tuned and it made 543 HP and 704 FT on a easy tune. It will easily handle 30 pounds of boost with no timing retard but only run 24 pounds.

In my case the engine management system is a XFI and the injector duty cycle did not increase.


Have a few questions does thickness of the head gasket on a 109 block have anything to do with it's lifespan ?

Should the head bolt torque be adjusted with the thickness of the gasket ?

Is it mostly the case that #1 and / or #2 cylinders are the first part (s) that let go (go lean) ?


Each time I have made changes to the system trying to figure out why it is getting lean on the top end.

This time getting rid of the factory fuel lines and adding bigger injectors.

you have a pm

 

[michael evans]

Also you mention bolts. Is there a reason you don't use studs?

I did say bolts when I ment to type studs.
I do have head studs.
Engine builder told me to torque them to 90 foot pounds.

 

[Pronto]

It's going lean on the top end? Not sure what you mean the duty cycle didn't increase. Do you mean it didn't try to compensate for the leaning out at the higher rpm/boost?

 

[captndave737]

Wow, 4 sets of head gaskets. I can't imagine. I've been lucky and never blew one. Is it the same side every time? are you getting any knock retard? If it were the same every time I'd be suspect of the flatness of the head or block.

 

[Pronto]

Was it the same combo and tune each time?

 

[dynoman]

I'd be suspect of the flatness of the head or block.

Have you had the heads checked ?? Even my NEW GN1's were not flat and had to be cleaned up !!

 

[Mr.Spool]

Have you had the heads checked ?? Even my NEW GN1's were not flat and had to be cleaned up !!

i found the problem if he wants to share its up to him as it was done in a pm

 

[Ttype6]

It will easily handle 30 pounds of boost with no timing retard but only run 24 pounds.

In my personal experience,I blew my first head gaskets at 10 psi of boost after switching to alcohol injection. Before that,I had been running 17 psi and 18 degrees of spark advance with 93 octane gasoline. After blowing gaskets several times again and again,I discovered that the alcohol controller was injecting greater amounts of alcohol than I was asking it to creating great amounts of cylinder PRESSURE. I am not saying that alcohol is bad,but my controller was.
I then switched to 110 octane gasoline and eventually blew the gaskets again,but it took a while. I did advance the timing because of the extra octane.
My next move was to switch to E85. I couldn't believe what it allowed me to do and I was still using the Felpro 9441PT head gaskets. Since I was ignorant about E85,I turned the boost up to 28 psi and advanced the timing to 25 degrees. The problem with this move was that I didn't know that E85 burns at a much faster rate than gasoline does. This means that you can't start the burn too early in the compression stroke or the PRESSURE will increase to a very high level before the piston reaches top dead center. If you switch to E85 after running high octane gasoline you must retard the timing because of its faster burn rate. Looking back,knowing what I know now,I still can't believe how long it took before I blew another set of gaskets,but I eventually did. Now I make 700 hp on E85 running 19 degrees of spark advance On the street. I have never been to the track.
Based on my personal experience,I believe that the number one cause of our blown head gaskets is too much spark advance if we are also running enough octane which leads to high PRESSURE at the wrong time.

Each and every time Iv'e blown head gaskets,I noted no knock retard on my data logger.I believe that I simply started the fire too soon resulting in very high cylinder PRESSURE on the compression stroke before the piston reached TDC. The octane was high enough to stop knock,but the cylinder PRESSURE was higher than the gaskets could contain.

In case I didn't explain my point of view good enough,I blame PRESSURE caused by too much spark advance.

 

[V6sleeper]

I bet its fuel pump volume with the stock lines.

 

[michael evans]

I understand your explanation well and I agree. Sounds like you also went though many gaskets to come up with the reasoning

I will also turn the timing down.

In looking back, the chip the previous owner (factory computer) had 26 degrees burnt into it.