[mcr98]

As the title says , I seem to be making 15.5 on the hit then starts to fade and only 13.5 on the top . Looks like it is a restriction on the intake side . I have imported blower , roto fab not big gulp and stock t.b. I tried a ported lt5 t.b. but no difference . Any ideas? Thanks for any ideas

[Chris 2018 ZL1 A10]

Wow, 15.5lbs, that’s double atmosphere! I’ll assume you’ve got some other information to record that number as the boost gauge in the cluster doesn’t indicate that accurately. I thought I read somewhere that 12.? was the max boost for OEM.

Also, when I occasionally accelerate hard, that boost gauge is the LAST thing I’m looking at!

[Stevezx900]

Originally Posted by Chris 2018 ZL1 A10

Wow, 15.5lbs, that’s double atmosphere! I’ll assume you’ve got some other information to record that number as the boost gauge in the cluster doesn’t indicate that accurately. I thought I read somewhere that 12.? was the max boost for OEM.

Also, when I occasionally accelerate hard, that boost gauge is the LAST thing I’m looking at!

I also feel like the last thing I should be paying attention to is the boost gauge as everything is happening so quickly.

Also slamming the gears on a 6M takes extra effort.

[mcr98]

It's on the dyno

[SFV1LE]

Originally Posted by mcr98

As the title says , I seem to be making 15.5 on the hit then starts to fade and only 13.5 on the top . Looks like it is a restriction on the intake side . I have imported blower , roto fab not big gulp and stock t.b. I tried a ported lt5 t.b. but no difference . Any ideas? Thanks for any ideas

Do you have experience with other forced induction cars? I believe boost pressure on FI cars always fades at the top, peak boost comes on early and correlates with peak TQ, then trails off some at higher RPM. I believe it's a function of increased airflow, it becomes harder for the SC or Turbo to keep up.

So with a Big Gulp or ported SC you'll see the same thing, but maybe starting higher then trailing to a higher number than the current.

[ZL1 1LmE]

I came from the supercharged Cobra era and did about everything imaginable to my car.

The Eaton superchargers (like most stock ones) lose boost up top due to temps and inefficiencies. That's why lots of people swapped to twin screws and other blowers.
Back to your original question, my Cobra made more boost than typical as my TB, intake and exhaust weren't maximized by upgrades.

[ZX-10R]

So what are your dyno numbers? As others have said it may be ECU programming and/or heat soak/rising charge temps (which happens fast on a dyno). Hope you have an ADM coolant reservoir installed to prevent air bubbles in the system

Always wanted to see a dyno comparison between the green filter (stock air box) and RF