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2002 Dodge Ram 2500 4wd 6 speed manual
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Discussion Starter · #1 ·
Hi, was looking at getting a set of DFI 6x.013 injectors. Pickup is a 02 cummins H.O. engine 6 speed manual still running a H.O. VP44. I have compound turbos. HX35/S475/96/1.15. I got the head O-ringed and was advised by the machinest/performance guy to use a .020 thicker head gasket. Would i need a custom spray angle injector or have to use different injector washers to compensate for the .020 thousandths lift? Still not sure if using a thicker gasket and dropping compression is what I want but im not the specialist either. The pickup is just for street fun and pulling trailers occasionaly. Any input would be appreciated. Thanks.
 

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I'm pretty sure the thicker gaskets are for use if the block needs to be decked. That's why they have .010" and .020" Thicker gaskets, to retain proper piston protrusion. I'm sure he recommended it as your setup should make power early but with o-rings and head studs a standard thickness gasket is fine as long as the block is within spec.
 
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Discussion Starter · #3 ·
I like my Power to come on early when towing i guess. I just don't really wanna sacrifice my bottom end by lowering compression. Not really sure how noticeable it would be:unsure:.at my power/boost levels I wouldn't think I should be concerned of peak cylinder pressures Especially with studs and O rings.
 

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Going from stock to .020" over will be noticeable from what I've heard. O-rings aren't even needed for your setup but is definitely good insurance.
 
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I got the head O-ringed and was advised by the machinest/performance guy to use a .020 thicker head gasket.
I'm purely curious- did the machinist give you a reason for going with a 0.020" thicker head gasket?
 

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Discussion Starter · #6 ·
Well you know how the game of telephone works so dont quote me but from what I comprehended he basically told me that when forcing that much air and fuel into the cylinders he likes to give it a little bit more of a combustion chamber. Im not saying he is wrong in all aspects but to me I feel it is being counter productive to the air fuel mixure by not compressing it more:unsure: maybe in a competition application this would give you longevity or even in a street manner but im not gonna be holding this thing at 70 lbs boost every time I drive it. Only when I need to try and not lose so bad to all these common rails running around🤣🤣 but all jokes aside im not saying i know more than this guy. Just spit balling.
 

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I really don’t think you have to be worried about cylinder pressure on a vp44 equipped truck to the extent of lowering compression. A good set of studs should hold down what ever you have planed, o-ring for extra security.
 

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On competition engines builders put thicker head gaskets or use pistons that lower compression but make up for it in cylinder volume.By putting a thick or lower comp. Pistons in the cylinder becomes bigger ,holding more air and fuel.So when you have lots of boost your putting more air in and fuel which makes more power.
It will kill a little response but more that make up for once the boost comes on.
For a street truck I'm not sure it's ideal.
Like you said most of the time your not running around on 70 psi.
 
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It's true you essentially make the volume larger for fuel and air however you loose out on thermal efficiency. Cr isn't static on a turbo engine either to make things more complicated, more air cfm into the cylinder raises compression. There is people that have posted results lowering static compression in the 600hp range and lost response and some overall topend. I do believe the trade off comes more in play at a higher hp level.

Here's a interesting thread if you dive into the theories of it.
Compression ratio - why lower it? - Competition Diesel.Com - Bringing The BEST Together
 

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Discussion Starter · #10 ·
Wow that was. Very interesting thread to read through! Thanks for that
 
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