Hey guys. Since I now have my Quad rail pressure gauge on the truck, I am trying to find out what a safe rail pressure is for highway cruise. With the MP8 turned off/all the way down, I see around 18-20k psi at cruise. Would another 2-3k psi be okay? I know there are mixed opinions on what a safe rail pressure is to keep the injectors happy, so fire away. Thanks!

 

i think thats high for highway driving. but not 100%

 

I get my best milage bumping up RP to about 16-18000 from 13500-14000 W/ my X2, but 03s run less RP than 04.5+ models. I would leave yours as it is, RP is only good if your filtering really well and your going for big power, I wouldn't roll around town at 20000+ ever.

That's not high for an 05.

 

What sw are you running Rob? If you are running high levels above 5 I wouldn't bother using the MP-8 unless you're gonna pass or need a little quicker boost occaisionally. I run sw5 on my truck and MP-8 on about 60% and was seeing rp#s at 18k while cruising. Since the 04.5 ups do have more pressure at idle and cruising you would want to stick to a lower level on the Smarty and a moderate % on the MP-8. IMO.

 

I rotate between 3, 5, and 7. I'm on 7 now, but will go down to 5 for a little and try some MP8 add. I miss the added response with the aftermarket turbo with the MP8, even with the 4.4 (I mistakenly said 4.3 in the original post). So is 20-21k at highway cruise okay on a 04.5+ truck? I haven't had the MP8 on the truck for a while so I suppose I just need to play around with it.

Thanks for all the help guys!

 

No...cruise at 17.5 for new trucks...maybe up to 19.

15-17.5 for oldies but goodies.

 

Yep, what he said. (according to Don M as well)

I can't get mine anywhere near 17.5 cruising, with RP1 on the smarty and the mp8 off I still see 18k at 70mph.

 

Okay, thank you all! I'm glad I asked because I figured 20k was fine. I'll run a lower SW when towing and keep the MP8 down. I went from SW7 to SW5 and noticed a 250 psi drop at idle alone! I should hopefully be able to regulate it to 18k or so w/ the MP8 and on SW5 with the 4.4 beta.