Combustion chamber in the wrong spot??

[Red97]

Not bad for the amount of times that got hot lol.

Right, had to have stopped 7-8 times at least. Also did a dyno run this am. Darn plug was loose.

Were you running Dominator?

Yes

 

[Bigmac]

View attachment 348367View attachment 348368

Well.... it was still running....

Was it detonating, or bearings going out? Looks like some debris on the piston.

 

[Red97]

Was it detonating, or bearings going out? Looks like some debris on the piston.

Don't believe so, no "pits" in the piston. Just some carbon spots. I figure it had close to 2 full tanks through it. It is thirsty.

 

[Bigmac]

Don't believe so, no "pits" in the piston. Just some carbon spots. I figure it had close to 2 full tanks through it. It is thirsty.

Did it have any scuffs on the intake side?

 

[Nutball]

Yes

Well, you tried. Not much more you could have done better except run Klotz so it would at least smell good while apart on the bench.

Do you think cast iron just can't transfer heat fast enough?
Is the piston diameter or alloy not right for an iron bore?
Do Iron bore saws normally have more cooling surface area and bigger fans? You already have to cut off a lot of the cooling fins just to fit such a big bore cylinder under the hood. Maybe this is a race only idea.

I'd like to see you make a diesel saw. There are non fuel injected 2 strokes in existence. You might need spark or something to start them with. Sometimes they route the fuel line around something hot (muffler or cylinder) to preheat it.

 

[Red97]

Did it have any scuffs on the intake side?

1 real light scuff on the intake. Off to the 1 side.

 

[Red97]

Well, you tried. Not much more you could have done better except run Klotz so it would at least smell good while apart on the bench.

Do you think cast iron just can't transfer heat fast enough?
Is the piston diameter or alloy not right for an iron bore?
Do Iron bore saws normally have more cooling surface area and bigger fans? You already have to cut off a lot of the cooling fins just to fit such a big bore cylinder under the hood. Maybe this is a race only idea.

I'd like to see you make a diesel saw. There are non fuel injected 2 strokes in existence. You might need spark or something to start them with. Sometimes they route the fuel line around something hot (muffler or cylinder) to preheat it.

I think a lot of it is the lack of proper fueling and airflow. After the first couple of sticks it seemed to settle in. And nowhere near as warm on the top cover.

 

[Bigmac]

1 real light scuff on the intake. Off to the 1 side.

Ok, you might be getting a light cold seizure, it happens all the time on Honda big bores, they need a lot of warm up time before running.

 

[Red97]

Here is the full build.

 

[Nutball]

A mark on the aluminum can really fool you into thinking you exposed a passage in the carb, but you have to make sure with a magnifier and better light. I had a hard time determining if I went too far on 2511t carbs, but turns out I never did, it was just an illusion. I would have machined where the big screw hole was, there's no passages there as far as I know.


So, there's only 1mm thick of aluminum holding that cylinder together? I wonder how much strength the sleeve adds.

 

[smokey7]

Just for reference, this piston is from a GM direct injected 1.5L gas turbocharged engine.
View attachment 348289

Plenty of edges and ridges on it. The dished portion is where the fuel injector nozzle directs the fuel, straight into the dish.

My god that piston looks like hell. What the hell they run in that thing crude oil? You always have nasty engines to work on.

 

[Woodwater]

Looks like a normal Diesel Piston. I haven't seen other ones in my Life.

 

[Ketchup]

Here is the full build.

Damn. That’s cool.

 

[Steve]

My god that piston looks like hell. What the hell they run in that thing crude oil? You always have nasty engines to work on.

Nothing, most come in with no oil.

 

[Maintenance Chief]

Here is the full build.

Ive seen you doing a couple of big bores for other people, you must have quite a bit faith in the process at this point. Anything you learned that really solidified it for you?

 

[Red97]

Ive seen you doing a couple of big bores for other people, you must have quite a bit faith in the process at this point. Anything you learned that really solidified it for you?

Nothing really, other than the disclaimer it will work till it dosent. Lol

It's not a big deal going 1-2mm over just getting the sizes right is the biggest thing.

 

[jacob j.]

Nothing really, other than the disclaimer it will work till it dosent. Lol

It's not a big deal going 1-2mm over just getting the sizes right is the biggest thing.

Are you gonna be ready to do a 58mm 394 soon?

 

[Red97]

Are you gonna be ready to do a 58mm 394 soon?

Whenever someone wants to try one. Sleeves are staying put, and sizes are getting hit. Even better just going a couple mm oversize.

 

[Maintenance Chief]

Whats your take on the port volumes being reduced by over boring? I mean ive got some old 10-10 's that are factory over bore (.020 and.030) and the absolutely feel strong.

 

[huskihl]

Whats your take on the port volumes being reduced by over boring? I mean ive got some old 10-10 's that are factory over bore (.020 and.030) and the absolutely feel strong.

I don’t think it’s a volume thing as much as a direction thing. Less swoop blowing the charge flat across the piston underneath the remnants of the spent charge once the bore is widened