Ah....I didn't even know Tommy sold it.....being away from home gets you out of the loop quick.

I hear ya on Bellflower's truck. Tommy's old Red truck with a Powerdyne is still around Bwk. too. Whose the new owner of the truck anyway...I know Tommy was getting frustrated with it not making more than 430rwhp when he put the cam in it. We also got a few trucks with nitrous around here as well but I know so many that was running it...I'm confused....all the trucks are starting to look the same....20's, cowl, stripes on the hood, and dumped exhaust.

Anyways....I don't like to street race mine either but I've got to start tuning mine somewhere at WOT....I got a secret place though.....its just a 20 min drive to get there.

Anyways, if its in Feb....I 90% sure I could make that....it'll just have to get closer to time....maybe Golden Isles will have opened by then. Is it going to have a 1/8th still or have they changed there mind again to a 1/4 again?

Sorry to get off topic.

 

Yeah, I know, the thread should die.... But to tie it all together regarding boost pressure, compressor efficiency, and IAT - air density, guys.

Pressure and temperature drive the actual air density (air mass for a given volume - say, a cubic foot). Normal units are lbs / cubic foot, or kg / cubic meter. Mentally translate this to air molecules / liter to get a feel for total power potential for a given engine volume.

Compressor efficiency directly affects the temperature rise of the air during compression - one reason that a properly sized larger compressor can generate power gains vs. an overworked small compressor that's operating to the right of it's peak efficiency island.

Here's a quick cheat sheet to give you a feel for how pressure and temp affect air density.

Illustrated general rules of thumb:

1% change in total (absolute, not gauge) pressure = 1% change in air density.

10 degree (F) change in air temperature = 2% change in air density.

Any questions, feel free to ask. I realize that the sheet's not real pretty... Ought to clean it up. If anyone wants a copy of the Excel file to play with, let me know.

PS - GA guys - I was out on St Simon's ( ) all this last weekend. Love that area.

 

That is some good information right there, thank you for sharing. So for example, if I have a Radix @ 7psi gauge that gets me 50% more density. If the temp is raised from 80* to 130* (50* rise) I subtract 10%. So my adiabatic efficiency is 80%? 40% total density increase?

 

Intercoolers throw a lovely little wrench in the works - they cost you some pressure but drop temperature.

Evaluate your system one component at a time.

Radix compressor out pressure = say 8 PSI @ 200 F (rough guess, I don't know where exactly the 112 compressor runs - somewhere in the 35 - 50% efficiency range. Yes, they're that bad).

Charge air travels through the intercooler core then makes it way to the cylinder (we often refer to temp and pressure at-the-intake-valve).

Charge air pressure and temp at the valve (the air density that the 'engine' actually gets fed) would then likely be 7 PSI @ 130 F. (Pressure and temperature drop across the charge air cooler core).

Handy way of evaluating what your intercooler is actually buying you - instrumentation costs start to add up though if you want to read and evaluate everything at the same time.

Edit - spelling fix. Time to go home.