New Best ET/MPH

Cobra912 · Sep 22, 2010

90lxcoupe said:
this is true, MLS gaskets require a surface of 50 RA or better to seal right. I used them on my motor without resurfacing it, but that was only because i had other issues with the way my block was o-ringed and the MLS gaskets were my last shot before i went and pulled the motor and had it decked. Luckily the gaskets did the trick.

I think for you MLS gaskets would be a terrible idea, since you had a ton of passes on the car there is obviously some reason you blew the gasket, if you put the MLS gaskets on there and this happens again say 10 passes down the road its not going to be an easy fix, your gonna burn up a piston. You gotta thing of the head gasket like a fuse, I'd rather blow a gasket then burn up a piston.

What was the temperature difference when you dynoed the car and when you blew it up? The air can really mess with the air/fuel ratios and i remember reading about a few guys with lightnings who had thier trucks tuned in the summer, hammer on it for months with no problems, then in the fall when its 50 degrees at night time they hammer on it, it detonates and kicks a rod out of the motor

Also i dont think the cracked intake had anything to do with this problem, if anything it would have caused a vacuum leak

Interesting points about air temperature, yes the car was tuned in the dead heat of summer, and it was super cool when it blew. But I was watching my wideband, not on that run but a few of the others and it got rich a few times 9.5% but never went lean. No signs of detonation, heads and pistons are super clean, no damage or scarring. Spark plug readings looked great. The other thing too is that I've had this tune for two summers and probably 100+ passes.

I think I'll avoid the MLS but there are so many choices out there, composite, graphite, copper, multi-layer steel, steel core laminate, perma torque severe duty, rubber coated copper, graphite coated steel core laminate, and more.

It's weird how it blew out the bottom and not through a water passage. THe oil was clean.

HotFox · Sep 23, 2010

There is no doubt in my mind that detonation caused your head gasket failure. Note the side it blew, near the exhaust port, the hottest part of the head. When detonation occurs combustion pressures can double or even triple. This is what it would take to blow a gasket like that, note how wide the blown part is. Alot of pressure was there to cause that wide of an escape path. If it was boost related or a matting surface issue it would have blown into water or between cylinders, the weakest part of the gasket with the least amount of surface. Also a lot the of Ford stuff blows to the inside (valley) due to the lower manifold trying to wedge the heads off the block. That is why it is very important to not over torque the lower intake.

Consider your wide band is in the collector and is giving average reading on a bank or both banks depending on location. So you could potently be lean in the back cylinder and rich in the front cylinders.

What cylinder is that back or front?

I would do some checking on your injector of that cylinder to makes sure it is not pluged or something.

Scott

Cobra912 · Sep 24, 2010

very good points, thanks for your input. I'm starting to agree that it may have been a lean condition in the #8 cylinder. especially after I saw this photo:

I was running VP 116 with regular 91 pump gas.

Cobra912 · Sep 25, 2010

wondering now if it was from banging off the rev limiter going through the traps because that's when it happened.

90lxcoupe · Sep 25, 2010

Yuou said the wide band was at 9:1, thats dangerously rich and maybe when it hit the limiter it lit all that extra fuel in the cylinder

Cobra912 · Sep 25, 2010

HotFox said:
There is no doubt in my mind that detonation caused your head gasket failure. Note the side it blew, near the exhaust port, the hottest part of the head. When detonation occurs combustion pressures can double or even triple. This is what it would take to blow a gasket like that, note how wide the blown part is. Alot of pressure was there to cause that wide of an escape path. If it was boost related or a matting surface issue it would have blown into water or between cylinders, the weakest part of the gasket with the least amount of surface. Also a lot the of Ford stuff blows to the inside (valley) due to the lower manifold trying to wedge the heads off the block. That is why it is very important to not over torque the lower intake.

Consider your wide band is in the collector and is giving average reading on a bank or both banks depending on location. So you could potently be lean in the back cylinder and rich in the front cylinders.

What cylinder is that back or front?

I would do some checking on your injector of that cylinder to makes sure it is not pluged or something.

Scott

90lxcoupe said:
Yuou said the wide band was at 9:1, thats dangerously rich and maybe when it hit the limiter it lit all that extra fuel in the cylinder

Yep I think you're both right. When I get this thing back together over the winter I'm gonna get it re-tuned on the dyno, may change things up a bit. I'll also see about getting my injectors flowed for extra safety.

Cobra912 · Oct 12, 2010

Well She's ripped apart with only the shortblock sitting in the ole' girl. Sad sight to see. Sold a whack of parts though and bought new stuff:

- Performer RPM heads 2.02's
- Comp Cams XE274HR camshaft
- Trick Flow 1.6 rockers
- Trick Flow 28oz SFI balancer
- ARP heads studs
- Fel-Pro 2804 gasket kit with 1011-2 head gaskets
- NGK 7173's

Thinkin about picking up a Proform (not Procomp) electric water pump. Did some research and while I usually stick to a known brand name they seem to get pretty good reviews. Better in fact then CSR, which is surprising. A new one at summit is $169, a Meziere is $319+ and a CSR is $330+

Car will be going 99% track duty now....

HotFox · Oct 12, 2010

Cobra912 said:
Well She's ripped apart with only the shortblock sitting in the ole' girl. Sad sight to see. Sold a whack of parts though and bought new stuff:

- Performer RPM heads 2.02's
- Comp Cams XE274HR camshaft
- Trick Flow 1.6 rockers
- Trick Flow 28oz SFI balancer
- ARP heads studs
- Fel-Pro 2804 gasket kit with 1011-2 head gaskets
- NGK 7173's

Thinkin about picking up a Proform (not Procomp) electric water pump. Did some research and while I usually stick to a known brand name they seem to get pretty good reviews. Better in fact then CSR, which is surprising. A new one at summit is $169, a Meziere is $319+ and a CSR is $330+

Car will be going 99% track duty now....

What heads were you running before?

Good start did you sell the Paxton yet?

I dont see any NOS stuff on the list, you better add that...

I know NOS is illegal on the street in Canada, is it more expensive to buy as well?

Scott

Cobra912 · Oct 12, 2010

HotFox said:
What heads were you running before?

Good start did you sell the Paxton yet?

I dont see any NOS stuff on the list, you better add that...

I know NOS is illegal on the street in Canada, is it more expensive to buy as well?

Scott

Perormer 1.90's. I got a smokin deal on the RPM's.

Didn't sell blower, can't decide what to do.

Not even sure how much is to fill, my budddy works at a speed shop and tells me I'd be smokin crack to switch over to spray. But man o man I see a lot of people running fast on it!

adamsgt · Oct 12, 2010

Cobra912 said:
Here's a vid:

YouTube - 1986 Mustang 10.73@125mph

very cool!

Cobra912 · Oct 14, 2010

THANKS!!!

10lb Bottle is 90 bucks to fill, won't be going to spray. Paxton will be staying! Think I'll buy a meth kit instead.

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