Engine/Transmission (1998.5 - 2002) Drive pressure

[KKunz]

How do I lower drive pressure? When I’m at WOT my boost is reading about 5 to10 psi less than turbo drive pressure. Drive and boost should be 1:1 correct? If I increase boost won’t the drive pressure increase also? Why does drive and boost need to be 1:1?

 

[Timebomb]

Ive been hacking at this one for a little wile. The short answer would be to put an external wastegate on the manifold. I have been trying to avoid this buy milling out the stock WG hole to about 38mm and making a new flapper (Hx35/ 14cm). Well that dropped the DP by about 5psi. Mine is still 20-30 psi more than my manifold pressure. So im kinda in the same boat.

Drive pressure should ultimatly be less than manifold pressure if you can get it there. The reson is with higher DP there is a chance of surge and also in the timming events of the cam when the Exh opens it forces out well if theres pressure there it may not be able to escape so when the cam overlaps (both valves open at the same time) the exh can go back through the intake. I hope that helped

 

[NoSeeUm]

I personally would not worry about 5-10 psi. In fact I would have been happy with that a year ago. My HX35 ran close to 70 psi drive @ 35 psi boost. It is not really a low drive pressure turbo by any means. I believe it was designed to spool well at low to mid rpm's the compromise being high drive pressures at high rpm.



I think that drive pressure is fairly hard to distinguish exactly unless the truck is put on a load dyno and ran at a constant rpm / load for time long enough for all the pressures to stabilize.



How much drive / boost are you making at WOT in 6th gear right before you get out of it?



Jim

 

[Timebomb]

I stop at 60psi thats 90psi drive Pressure at 2600 rpm. It will make more I just dont want to push it.

 

[Forrest Nearing]

you're just leaving horsepower on the table... not really hurting anything persay.

 

[Highfinance97]

Can you guys show me a picture of how you are checking your drive pressure,



I have my copper tubeing coiled up but i think it keeps getting clogged with soot and it stops reading pressure



I was at 1:1 with the other injectors, now that I put new ones in id like to see what it is



Michael