I just installed guages the other day on my 98' 12 valve. I was wondering what the boost should should be going down the road at 70 mph, empty with no head wind? With my mods, it will push 33 psi. The truck is pushing bout 8 to 10 psi at 70 mph. Is this right or what?

 

mines not a 12V'r but 24V'r and I think that is about where mine runs on a straight stretch of flat ground at 70.

 

Boost is a product of several variables.

Engine load.

Fueling rates.

Speed (engine load again).

Headwinds on highway or towing large objects (engine load again).

There are alot more factors, these are just what came to mind at the moment. I also read where people install a HP cam and see a boost drop and wonder why. No magic there. The valves are letting more air into the cylinder at a time and that decreases boost.

Get to know your truck and its characteristics and you will be able to diagnose problems much more easily in the future.

Also monitor EGT's as they coincide with boost.

I hope that helps.

Ronnie

 

I have about the same in boost going down the road at 70. I was always told that keep it under 10 PSI boost and you will get better Mileage. I never thought of it that way, so i did a test. The higher my boost the lower the mileage I got. If I keep it under 10 and keep my right foot out of the throttle, and go just a bit slower, I saw a huge increase. I am no expert but I slowed down on the freeway. The nice thing is that at any point I can take off if needed. Just my 2 bits.

 

I get about 9-10 psi at 70. About 7 psi at 65.

 

8psi at about 650* EGT on flat road at 70

 

Thanks been putting the gauges off for a while. Its nice to know what's going now.