Competition How Low Can You Go?

[JTrantham]

What is the lowest compression you would consider driving on a regular basis?



Jonathan

 

[Forrest Nearing]

for a daily?



I'd say whatever a mildly set of notched marine pistons gives you... 15. 25:1?



really low compression is really only a benefit at higher RPM w/ huge boost numbers...



if you're going to be pulling w/ the truck competatively, you could sacrifice a little drivability for the sake of raw power in front of the sled.



but if you're talking about a daily driver or even something that's going to the strip now and then, you need to consider area under the curve. you need compression to get the truck moving and get the turbo spooled!!!



realize that most NA diesels are 19-21:1 compression, so at 16-16. 5, our trucks are already "low compression"



low compression reduces cylinder pressure at a given boost level... so say you can run 70-80psi on stock compression w/ o-rings and not have any problems... drop it down . 5-1 point and run 90+...



if this is a daily driver that's only going to see 60-70psi, there's not really any benefit to dropping the compression ratio at all IMHO.



if I could the benefits of a marine piston without dropping compression, I'd do it... I'm shooting for 700+hp eventually... and I've got an automatic that can get up on the converter at the strip... a manual would be even worse at the strip w/ low compression.



hth,



Forrest