Engine/Transmission (1998.5 - 2002) Latest oversize head gasket??

[ynot]

Hi guys. Long time... What's the latest and greatest oversize (thick as possible) head gasket that the "twinners" are using now? I've heard copper, graphited steel, etc... but no numbers, locations, longevity, etc. She'll be G10 studded for sure this time, at least, but we need to drop compression this time. Thanks... T

 

[HVAC]

You can get copper in . 030 over. Or the 12v gasket gets you . 020 over stock.

 

[Jim Fulmer]

I'm going with a . 020 over fiber gasket, O-ring the head and a stud kit. My Twins are smaller than Nowell's and just don't work good over 70-75 PSI.



Jim

 

[J.R. Adkins]

You can get a . 110 copper gasket for LOW compression.

 

[ynot]

Thanks for the reply, guys. Ya'll have a formula (or a good guess) as to what theoretical compression drop would be with the . 030 or . 110, and where to get them? Is the only long term fix for external coolant leaks o-ring? Hard to believe Cummins long time rubber grommet use didn't make it to this one. I'd imagine I'll be shaving the head . 003 or . 004 to make flat again, or buying a ported casting to build (milled/ Re-Con). May as well upgrade while I'm in there. Any more thoughts while we're here (HVAC, I'll call you around 1:00 your time [Sunday]). Thanks guys... T

 

[willyslover]

Tony. . This is on my short list of things to do also. . the darn ETH compression is our enemy as you already know.



How many gaskets have you lost now ?



Nowel and I haven't decided what is best for mine yet as there are issues no matter what you decide to do... I'm kinda in limbo waiting to see some results this spring at the pulls, as some have tried a couple of different things with ring styles lately.



Good to see you hammering the keys again



Gary

 

[ynot]

Hey Gary. Ya, long time, but good to see the "old timers" still hangin'. This is my first HG loss, but I retorqued when the DDIII's went in 100,000 ago. Losing coolant at the front ex. side with the new VP44 and timing box. I'm not gonna go all out, as I'm still just running the mid 50's with the single HX35, but studs and porting are a given (while we're there). May just try the . 020 12v gskt and punch out the water holes. Any thoughts on porting? Call me on the 800 if you'd rather, and I'll call ya right back. Be cool... T

 

[HVAC]

Mathmatics

Tony, check my figures---





Displacement = 60"^ (^=cubed)





To find combustion chamber area---



ETH compression ratio = 17-1 (?)



So take the displacement and divide by 17, or 60/17=3. 5"^





To see how much area we add with a . 020 thicker gasket---



Bore = 4. 02, radius = 2. 01



2. 01(r) x 2. 01(r) = 4. 04 x pi = 12. 69 (area of bore) x . 020 = . 25"^



So the 12v . 020 over gasket adds a cubic quarter of an inch.





To find the chage in combustion chamber area---



3. 5"^ (combustion chamber area) + . 25"^ (additional area) = 3. 75"^ (new combustion chamber area)





To find the change in compression area---



Divide 60"^ (displacement) by 3. 75"^ (new combustion chamber area) = 16





If this is correct, then you have dropped a fuell compression ratio!!!

 

[ynot]

Hey Nowell, I'd like to know how you keep the wheels turning like that on SUNDAY!! I'm still trying to figure out what I did yesterday Rumor has it (your equations also show this) that . 020 drops it around 1. 1 (1. 0 to 1. 2 with standard bore and . 002 bore wear respectively). ETH's are 16. 3/1 ETC's at 15. 7/1. HO OEM max is the 370 6BT marine at 14. 5 or 14. 6/1 depending on CPL and year. . 0015" bore wear at 100,000 mls and de-carboning the crowns with a . 020 gasket would land about 15. 2/1, and . 025 would be 14. 9/1(+/-. 15). A . 020" gasket and a 2 to 3 degree timing bump with the resulting power ramp/ curve and all the fuel and boost we run is as close to perfect volumetric/ stoichiometric efficiency as we can get (I think). Any thoughts on internals or porting while I'm in there? Thanks guys... T

 

[JJW_ND]

Intersting reading.

I was told I dropped about . 5 point with a . 020 gasket and . 008 milled off. Would have rather used a . 010 but parts never made it. Shop I used loves high timng. They set mine at 20 degrees. It sure runs good and revs clean and fast. Even with very cold engine temps.



I would assume cylinder pressures (as related to high timing) are somewhat offset by lower compression.



So can one assume you could get away with higher timing (18 - 20) if you have atleast a . 010 gasket added over stock? or is this wishfull thinking and ones days are numbered before gasket problems?



In my case, I am very mild with HP. Boost never gets over 34 with stock Turbo and just a 16cm.



I really like what the higher timing did for winter driveablitiy, but do not need to have another headgasket put in. Orginal replace due to coolant seep near TStat area. No HP, BOMB damage here... ... yet!



jjw

ND

 

[ynot]

jjw, their guess at resulting compression is about right, as is the timing (obviously). Fast timing is good when everything else is right, but too fast kills stuff (and costs power. You don't want to push too hard on the piston before TDC, as it fights against itself in climbing the hill towards TDC, the by-product of which is also heat). Cylinder pressure isn't so much lowered by lower compression, as much as it is spread out more over a longer period. The end result is a longer power band per stroke and less heat internal and in the exhaust. It is actually trading efficiency for torque, tho the efficiency loss is more in NOx than mpg. I'm making up a generic power curve graph for HVAC right now to reference this. Not sure if he'll post it or not. Hope that helps. Be cool... T

 

[willyslover]

Tony... IMHO at our HP levels we don't need to port the head... . now at Nowels level he is looking for every single HP... I believe a 24 valve breathes well in stock trim till way over 600

so where did you want to end up HP wise ???

just MHO. . a clean up & gasket match for initial entry flows will be just fine.

 

[ynot]

Morning Gary. I concur. Don't really care what kinda numbers it has, just longevity with what I have now. Just makin it breath a little easier. Nowel and I talked about it at length yesterday. Just gonna knock down a couple high spots in the head, gasket match the exhaust, and call it good. I'll keep ya'll posted on the studs I end up with and stuff. Thanks for the help, and ya'll have fun over there! Be cool... T

 

[willyslover]

One thing I might suggest ... an ATS manifold to replace your stocker... some day you'll have to replace it anyway [especially since you see 50+ lbs. of boost. . that puppy is seeing nice heat and will shrink]



I also need one of these