Head gasket problem ???


I was away at the weekend trying a standing mile event.....even though the organisers timing gear didnt work, and they dropped it to 7/8th mile...
Then my "new" alternator packed in during my first go, along with several other problems on the day.
Really, I shouldnt have bothered.

Anyway, on my own datalogs, I did hit 198.3mph on my 2nd run over the 7/8th mile...so very close to the magic 200 I wanted, and in a shorter distance to boot !!


Thats not the issue though. On my last run, I had a problem....head gasket related. Huffing and chuffing, temp gauge into the red, I limped back to the paddock area, temperatures back under control by time I got there.
Yes, it had lost some water, but it was no longer pressurising the cooling system ( once again, it went from 7-8psi to about 30psi for a few seconds, then returned )
Its also melted 5 out of 8 plugs....Im getting good at this

Cutting a long story short, and adding pics that we all like to see...... First noticeable thing were markings on the exhaust manifold around cylinders 4 and 6.
This is them off the car, although I dont have the engine out just yet.

Anyway...pic 1, and no they arent ceramic coated



Now a closer look......at what used to be smooth stainless !!!!



Mmmmm not good. Do you think a leakdown test might show anything ???

Looking towards the engine, I think I have a problem





Do I win any prizes ???






Unless my wideband isnt working properly......I dont think AFR's were that bad in general. EGT's didnt go above 800degC ( cant be arsed converting )

Although bare in mind, I was only running 11 volts due to no alternator. Fuel pressure was ok, and AFR's were ok.
As always I have silly amounts of timing though....circa 26deg, 8.8:1 CR, pump+meth with not that much boost, as it too was backing off after 6000rpm, with the new smaller pulley I fitted.....and obviously didnt do what I wanted, MORE boost !!!!

Im beginning to think my wideband isnt quite right !!!!!


Im pretty sure the block is scrap....but what about the head ?

TFS 225cc......what are these made from, and what would the welding procedure be for repairs ?

The engine runs, and does not pressurise the cooling system.

 

Damn you torched it good Worst thing about standing mile/distance runs is how hard it is on a engine. A LONG pull will destroy a engine if the tune-up is not right on. Sounds like you were detonating it pretty bad. And your EGT's might not be correct if your header got that warm and the torch took over. Ever seen a alky car get away from it? Same concept, just bigger holes lol.

 

Are you adjusting the AFR for the meth

Thats plain and simple detonation, if you are going to be making 200mph runs I'd be looking at running some real gas.

I'm sure the head can be repaired, but I bet you need a few pistons as well.

26 degrees leaves you zero room for error on pump gas/meth, I run 15-16 degrees of timing with C-16. With 26 degrees mine would probably do the same thing in a 1/4 mile

 

4 bolt heads will lift and blow flames through and torch everything when even light detonation occurs at the boost levels you're running. 26° is too much in my opinion. I run 18° on pump gas and meth and have 0 knock. You might get your injectors flowed to make sure they aren't causing a lean cylinder. The head can definitely be tig welded and resurfaced and possibly the block. Sorry to hear about your plight!

 

Im not overly concerned about the damage.....more why, but Im putting it down to me being stupid and running the car with no alternator primarily, with tuning second.

Injectors are ok....this damage is not limited to one cylinder. I know this without taking it apart.

Yes my timing is high etc etc......but that hasnt changed all year. Ive done maybe 30 1/4 mile passes at that timing, and similar logged AFR's, and in much warmer temperatures.
I also did 3 x 1km runs only 2 weeks ago, which isnt that much shorter than the 7/8th mile of this event.
I'd need to check laptop, but boost was around 17-18psi at 6000rpm, but it backed off after 6000rpm to about 15psi.
So boost wouldnt even be as high as I had been running ( 22psi at 7000rpm before )



Here is a question though. Ive been using this same FJO wideband for a while, albeit on a new NTK sensor a year or so ago.

What affect would running the wideband with 11.0 volts be, instead of the normal 13.8 volts it should be getting ? Would this affect its 0-5v logging output ??

Also...I have a 12volt powered AT driver, for 0-5v logging of EGT's...would its output be affected by powering it at 11volts, instead of the normal 13.8 volts a car would see ??

 

I wonder if this might be a case like when you pass your hand over a burning candle (like a 1/4mi run) vs. holding your hand over a burning candle. ( 1mi pass)

I never burned my hand passing it over a flame at a reasonable speed.

 

Forgot to say..logged AFR's are mid 11's as per usual.

Although oddly....I did recall seeing several 12.x's on the display during the run, and thinking....I dont like that. Needless to say in that short space of time I decided WTF and kept the foot in. It had been ok on previous runs, so why not again
It hasnt logged many 12.x AFR's though, which is odd.

I only log AFR's on the left hand cylinder bank......this has suffered less damage than the right hand bank.

 

Low voltage can change the injector duty cycle, lower fuel flow from the fuel and meth pumps and a weaker ignition but the 0-5v supplies are regulated and should be fine down to 8V or so. As far as the wideband I'm sure its using regulated supplies and I would guess 11V should be fine.

You may be able to get away with 26 degrees for short bursts and not hurt a thing but running at high RPM for extended lengths is asking a lot from pump gas/meth with that much boost. All it takes is one hot spot and once it starts melting away that hole is there in a second or two.

 

Seems like you are allways blowing something up steevie lol.

26deg is a bunch even for a pump gas street car, 18deg is about where it needs to sit.

What were your IAT's?

 

Immediately prior to the bang.....

AFR's were 11.7-12.0:1,
IAT's 70degF max,
Boost 19psi,
timing 26deg,
EGT sub 1500degF ( logging probe in cyl 5 ) In car gauge on cyl 7 too, dont recall it getting too high either.
Batt voltage 10.9 volts.

It let go at around 6300rpm.

This was my 3rd full attempt of the day, netting a max of 192.3mph before the line, crossing at 191 according to their timing gear...the only damn run when it worked !!!!
Gasket blew before a little bit the line though.

My first run of the day netted 195mph, 2nd run 198.3mph.

The blow up was the 5th run, runs 3 and 4 had problems so were aborted ( boost pipe blew, then had crank sensor wire break )

 

Alt went out, you lost power to the injectors or something? I thought you didn't tow the car, how did you get it home?

 

I woulda thought for that boost/timing even with meth you woulda wanted to shoot for more like a 11.5 AFR.

I second all on the timing issue though. Even if you weren't detonating running that high of timing puts significantly more load on the head gaskets because you're getting a harder peak combustion closer to TDC.

 

Meth lowers the required AFR, running 11.5 is even iffy. Think about it, if the burn AFR of meth is near 5.0, and your adding say 20% of your main fueling via meth, then you will need to change your desired AFR.

Still, high timing, high AFR, is a cocktail for destruction

 

Recovery service !!!!!, First leg of the journey...small recovery only allowed to travel 62 miles now, so had to transfer to 3 other flatbed trucks to the ferry in Scotland, then a further small van to get me home.



Alternator out only means it isnt charging around the 13.8-14v mark.

I was charging the battery on the day via another vehicle in between runs via jump leads. I tried to drive it home with the blown engine.....but local police stopped me coz of the noise it was making lol, and told me to get it recovered.

Circa 450 miles on this one !!!


As for the AFR's....Im not even 100% sure the recorded AFR's are actually correct given the apparent extent of the damage.

 

Way too lean IMHO. I wouldn't go more than 11.2 at most and would never go without an alternator-pumps need those 13volts or more, when my pump voltage drops flow drops signifigantly.

 

With hindsight.....that was leaner than I usually run. Normally It might see some high 11's, but typically its mid. Under normal use, it would never hit 12.0's

I was simply stupid for running with a lack of full electrical power. When you drive 500 miles and the goal is so close....and things appear to be holding together. Its hard not to have a go



Who can supply me these the cheapest....

LS2 block.
custom pistons/rings to suit.
LS2 Valley cover
LS2 lifter trays
ARP head studs.

The above is the cheapest, most sensible option for getting it back together, re-using my crank/rods etc etc etc

 

i did this a few years ago, thought i was pretty bad *** when it happened... at first i thought i blew the spark plug out the hole.

the steel sleeve was ok so just replacing the gasket was ok, and the head was repaired for $50 locally

i guess it just lifts the heads so bad that the 'burn' picks up oxygen outside and burns lean and hot enough to melt the aluminum.

once the cyl is open then it probably gets worse and worse while driving around like that.

i been there before.. think back and compare the price of the above to the price of 5 gallons of good fuel it will start to make sense.

 

Same as me, immediate thought was a spark plug !!! I drove the circa 2 miles to get pack to the paddock area. I knew something bad had happened, and removed spark plugs, injector wires and coil wires from cyls 4+6, as I knew the biggest problem was in that area. Thats how I tried to drive it home lol

Good fuel perhaps...but if it isnt running safely with regards to timing and fuel.....end result will be the same.
Im not blaming the fuel here, this is all my own fault. Ive run miles before, and 1.25miles, albeit with less power. This is entirely a tuning issue....not fuel.

More piccies......and more carnage

Cylinder 6







Cylinder 8...its nice !!!!



On another matter.....

Cylinder 2. Head burnt away between valve seats a little.....But more notable, the intake valve face is no longer flat.
It has pulled into a concave shape, to the tune of 198thou from the edges of the face.





When I bought the heads, installed valve heights were pretty much 100% true, all the same. This is no longer the case. Not to the extreme above, but they have all changed slightly.

The bottom end is fair game, I fucked it....I wanted to upgrade to an LS2 at some point anyway.

I just hope my heads are repairable

 

Man you are hard core, thats a long way to go and a lot to go through to get to the 200mph mark. I dont blame you for trying, even with low voltage and going a little lean when you were that close I would have done the same thing

 

Google maps...

http://maps.google.co.uk/maps?f=d&sa...,13.974609&z=6