I have purchased a Kwik-Spool B-1 with a billet external wastegate. It hasn't arrived yet but before I install it I was wondering if there is a way to measure driveline pressure. The way I understand it, ideally I would want to run a 1:1 boost to driveline pressure to get maximum performance. Would someone please explain this to me and is there a guage to measure this??<br><br>Thanks,<br>Meacham Evins<br> ??? ??? ??? ???

 

To measure drive pressures you might be able to use a 60+ psi boost gauge and a long piece of copper tubing.

 

Most of the guys that I've talked to have tapped their manifold just before the wastegate, then run a brakeline fitting with a 2 - 3 foot piece of steel tube off of it. From there, they've run 1/4&quot; flex tube to a 60 or 80 PSI boost gauge.<br><br>And you are looking for the lowest drive pressures at the highest boost pressure, while staying inside the efficiency map of the turbo. With your KSB1B, Meacham, this is should be somewhere between 42 and 48 PSI.<br><br>Rod

 

Could someone please define driveline pressure?

 

Its actually &quot;drive pressure&quot; It is the back pressure in the manifold/volute before the turbine wheel. Measured in KPA or PSI. 1 to 1 is of course 1 PSI of drive pressure to 1 PSI of intake manifold pressure. Most factory gassers will run a much higher drive pressure than boost pressure in the top rpm ranges. Diesels can as well. There is no magic number but the 1 to 1 seems to be a general rule of thumb to follow. The drive pressure can go much higher than 1 to 1 and the engine still make great power. It all depends on many factors like camshaft timing events, fueling levels, etc.<br><br>When turbos are tested on diesels using an engine dyno you look for what is called a crossover point. Its cross plotted on a dyno graph between all the operating ranges. Crossover occurs when the drive pressure exceeds the intake manifold pressure. Changing cam timing events, turbine wheel sizes/types, turbine housings, nozzle size or nozzle ring configurations, exhaust system parameters, etc can help to change or tune in the crossover point. <br><br>Cummins has a good exhaust scavenging effect for a stock engine using stock parts. Once parameters change from additional fuel or additional boost, etc the crossover point and drive pressure curves change as well. <br><br>Don~<br><br>

 

Don M. Thanks for the nice technical explanation.