Competition Head sealing methods - what's not been used yet?

[T. Baker]

I'm not sure a diesel will run with a 10 to 1 compression ratio and no boost. The lowest I've ever heard of is somthing like 13. 5 to 1.



A lot of the older big Cummins engines have a thick (1/16" or so) single layer steel head gasket - talk about tough!!



There are such things as headless engines where the head is not seperate from the block. No head gasket to blow! The valves are either machined from the bottom or the valve and seat screw into the head. I'm not sure why more engines aren't made this way now days.



Old time Herculese engines head studs go all the way through the main bearing caps! Another great idea that should still be around.

 

[HoleshotHolset]

"I'm not sure a diesel will run with a 10 to 1 compression ratio and no boost. The lowest I've ever heard of is somthing like 13. 5 to 1. "



Well... I don't have any firm numbers. BUT, have you ever been to a tractor pull? The really low compression diesels don't exactly run well until they're above 3000rpm or so... when they let the clutch out @6000rpm+, most of the white smoke has turned to black and they smooth out real nice.



So - a diesel will run @ 10:1, but it won't run very well until you start bringing the rpm's/boost up... Not to mention - some pullers need to run a coolant heater even in the summer... AND a big 'ole shot of ether.



Matt

 

[cumminspwr01]

What if you went with a CR in the 12-14:1 area. Would it still be ok to drive on the street and still make enough power increase to justify spending the amount of money it takes to get the lower CR. I've been thinking about this for a while since I would likr the increase in volume and I'm already at 17. 25:1 with the HO and i am planning on having the head shaved to true it up and probably having the block decked. That would make the compression ratio even higher.

 

[Jim Fulmer]

You guys have some good info going on here. Running low compression on the street (after you get it started) is kind of like running more and more timing. At 18 degrees or less the engine is normal, 20 it runs on the border and after than it starts taking away from the bottom end and driveablity, the chargers will spool a little slower initially but will hit hard and top end power and egts will be better. I've tried 20,22 and 25 and there all give and take, the HANG ON ride at 20 is different than 25 but the chargers will light 200 rpm later(on my truck) at 25 vise 20.



The guys pulling are coming off the line at real high RPM were guys like us are coming off at what 2K or less, they have a chance to get things going. If we tried even a portion of the fuel or timing they run we would blow the fire out... ... been there!



What's the best compression to run on the street... ... . it's called R&D! from those willing to try.



Jim

 

[HoleshotHolset]

Jim: You made some excellent points...



Low compression/HEAVY fuel diesels blow white smoke like crazy... I don't think there's a state in the Union that would let you drive more than 10' down the road with that kind of Spy Hunter impersonation.



IMHO, you could get away with a more radical setup if you had a manual transmission... all the low compression/HEAVY fuel setups I have ever seen run don't even begin to smooth out until at least 2500rpm - even then, they're still smoking like crazy and running awefully rough.



If you want to make a lot of power - start with Jim's recipe. If that's not enough for you... spend more $$ and get back to us. His truck is still VERY streetable and makes gobs of power.



Matt

 

[CumminFast]

I dont think the smoke is really an issue. My truck white smokes terribly for the the first 5 miles, but clears up somewhat. but the truck is always white smoking at idle even at 95 degrees Farenheit. Hopefully my new cam will clear up my custom injectors a little. Streetability is really in the eyes of the beholder. But I think shaving the pistons just a little is the trick to an "everyday driver" whatever that is.

 

[HoleshotHolset]

"Streetability is really in the eyes of the beholder."

... or the law enforcement officer riding behind you.



Law: "Don't you think it smokes just a little bit too much?"

Anonymous: "No, not really. "

Law: "The only time I could see the truck was in-between shifts... "

Anonymous: "Oh, whoops... "



:-laf



Matt

 

[GO 4LO]

You could see me between shifts? Must have accidentally left it in valet mode .....

 

[HoleshotHolset]

Actually - the 'anonymous' person that got in trouble with the law was driving a VW. :-laf



Matt

 

[ThrottleJockey]

CumminFast



My truck white smokes for a couple of miles too, with the Schied pistons in it. Would a timing advance clear this up until the water temp reached 160 plus, or no?



Brian

 

[CumminFast]

I don't think it will ever clear until the water temps get up. Your timing really needs to be set on a dyno to really get it right. I know on my truck, the gasket b/t the exhaust manifold and the small turbo was leaking, and when I would let the truck warm up it would leak fuel out of the exhaust manifold. A big fuel supply may contribute to the white smoke. But to be honest I love the hell out of my white smoke.

 

[ThrottleJockey]

Yeah, me too. It does look pretty cool!

 

[John Robinson]

The white smoke is because of timeing, When the cylinders are cold, the compression in the cylinder is lower. Meaning the piston has to come up higher in the stroke in order to fire. White smoke is always timeing or air "excluding antifreeze".

 

[supersonic]

not trying to tell you what to do but y'all dont need 10:1 CR for street trucks.

I wouldnt run less than about 15-15. 5:1, mabie as low as 13:1 in extreme cases for something that is streetable with the timing and injectors tuned to the charger. We only run in the ballpark of 11:1 in the pulling truck with big timing, injectors and somewhere between 160-220psi manifold pressure, but like was earlier mentioned, they dont start to come alive till you get over 3500 RPM, which is quite dependant on elevation, ambient temp, humidity, etc.