Guys.

This is first time in summer when I've started monitoring things. I'm only running 7psi but seem to make 6.5 at redline with aftercooler.

It's probably 20f hotter than it has been in winter and it appears i've lost 1psi at redline does this sound about right?

I know the principles behind it but seems a bit much? Or am I having belt slip? Doesn't look like it's slipping but could be wrong according to the boost gauge.

Thanks

 

With a blower the only constant is the rpm of the blower at said engine rpm. If air is hotter it's less dense. Then it's compressing less of it. So less pressure. I saw same thing on my roots setup. I would gain 1-1.5 psi in winter time. I think ur ok.

 

Thanks man, will check belt too.

My boost gauge reads -0. 5 ish when ignition is on, bit engine not running surely it should be 0?? Though my boost gauge is cheapish just a vac line going to an analogue gauge.

 

Sounds about right, i pick up anywhere from 1.5-2 psi when temps get around 60, my tune dates have been when its 90+.

 

Just checked and logged, its appears the belt was just a little loose.

Also I added a damper (small fuel filter) inline with the boost sensor and its made a massive difference, it hardly fluctuates now!

 

Weather will mess with boost a lot, especially a belt driven setup. If you're not at 0psi with the motor off then that's because of the weather. If you check the local weather and pay attention to the barometer your boost gauge should line up with that. Higher barometer and the gauge will be on the higher end of 0, low barometer and the gauge will be on the low side of 0. Altitude plays with that too as the higher you go the thinner the air. I'm at sea level and typically I see 0. When I went to the blue ridge parkway at the peak, 6200 feet, I was down 2.5psi.

Right now it's hot as balls though and I'm probably down 0.5-1psi compared to 60-70 degree weather. This is normal and a side effect of a belt driven setup. Turbo kits are effected by this too but can make up for it. On a turbo setup if you had an electronic boost controller it can make up for the slightly thinner air by having the turbo work a little harder to hit your target boost.

All that said if you have a mechanical Autometer gauge they're not all that accurate and shouldn't be taken as absolute truth. I've had several over the years because they're reasonably priced but they all varied by as much as 4psi. On the same setup no two would read the same, I think they cheaped out and went overseas with production. That's why when I had my Hondas I ran the AEM serial gauge in place of the Autometer gauge, then I finally had an accurate number.

 

Thanks for the info