F8L Z71

I have been racking my brain trying to figure out why my #s are so low with my amount of boost (In PSI) and I keep forgetting that PSI does not equal CFM. I look at Parish's truck and his dyno figures and I'm like "he's only running 11.5psi on that dyno and he made 497 or so HP"

Then I remember that he is running a 6.0L which obviously makes more power BUT more importantly displaces more air than my 5.3L so 11.5psi on his truck would equal more PSI on mine. Maybe about a 2-3psi difference. Also he has a bigger turbo that is pushing MUCH more usable CFM even though he was at 11.5psi than my lil turbo at 13psi.

Sorry Jim, not trying to use you as an excuse for my #s rather I am using you as a good example since I know your system enough offhand to recite it. LOL

Anyway, I just wanted some of you that are already using FI or thinking of going into it to remember that psi does not mean CFM and there can be a big difference between the 2 when it comes to the type and model compressor you are using.

Then again I'm bored at work and blowing about as much hot air as a Whipple in July in Arizona

Ryan23silverado

iTrader: (1)

How about a roots or a turbo

CFM vs PSI is a good thing to understand and remember

383838

iTrader: (1)

Yes, but also Parish has a much more efficient setup. My truck as a 5.3 at 11psi made 477rwhp and 557lb/ft if I remember right. Don't rack your brain over it, your turbo setup is very different that Jim's and mine.

HAZE

huh ? what is usable cfm ? if the boost is measured at the intake and remains constant isn't the compressor putting out as much "usable" air as possible ? i realize that the larger displacement motor can push more air, but more "usable" air would directly be represented as higher boost pressure. if the boost does'nt drop off as rpm's increase, if it keeps building pressure, then is'nt it supplying adequate cfm ? and yes if you ran the same setup on a smaller displacement motor it would increase the available air, but there should be a corresponding increase in boost pressure. so it seems this is all about size and air restriction. ..... wait what was the question ?

F8L Z71

F1RZ06, I wanna know how your systems are considered more efficient? Just curious as I am still learning about turbos. I am trying to work out some ideas on how why my #s stopped climbing yet stayed flat for 2000rpm and the more I learn the closer I may get to figuring it out.

Etc, When I said "usable" CFM I meant not super heated air. Like when you overspin a smaller compressor and end up heating the air to a point that you are not gaining as much HP as you would had the compressor been more within it's eeficiency range.

My turbo kit is still in it's infancy and there is alot of testing being done to find the right compressor size and A/Rs to work at making high HP #s. Hell little over a year ago Garrett themselves said a rear mounted turbo wouldn't work when STS approached them. Now look at what they are doing. They indeed work, maybe not as good as a front mount kit but I bet ya anything they are damned close if all parameters were the same except the rear vs front mounting. My dyno sheet was ran unlocked. When he locked it at 10psi I gained 15rwhp but since I could care less about peak dyno #s we kept tuning it unlocked. So for a first time out that put me within 50hp or so of Parish's dyno which could easily be made up by the bigger displacment motor and turbo. Not to bad for a kit everyone said was junk and wouldn't work.