Can U explain turbo specs?
Thread Starter
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Fleet Mechanic
Joined: Feb 2004
Posts: 1,816
Likes: 3
From: River Valley AR
Can U explain turbo specs?
What does the 1.15ar, .84ar, and so on represent? I have kind of guessed that the bigger the number the bigger the flow, but what does the number represent?
FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
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From: Cabot, Arkansas
Ah, I knew I had it saved somewhere.
Your exhaust housing has two holes in it... an entrance point and and exit point. These are the A and R values. A being the exit area of the turbo housing, and R being the scroll radius - or basically the entrance area for the turbo housing.
Your exhaust housing has two holes in it... an entrance point and and exit point. These are the A and R values. A being the exit area of the turbo housing, and R being the scroll radius - or basically the entrance area for the turbo housing.
Thread Starter
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Fleet Mechanic
Joined: Feb 2004
Posts: 1,816
Likes: 3
From: River Valley AR
Cookie you have given me exactly hat I was asking for. Unfortunately you have introduced me to some new terminology so I now have more questions.
#1- If the turbo exhaust exit is 1", and the inlet is 1.15", would that be a 1.15ar or do i have it backwards?
#2- Two turbos with different ar ratios- can they both have the same guts on the intake side of the turbo?
#3- Is there a comparable ratio for the intake side?
Thanks for the reply
Dan
#1- If the turbo exhaust exit is 1", and the inlet is 1.15", would that be a 1.15ar or do i have it backwards?
#2- Two turbos with different ar ratios- can they both have the same guts on the intake side of the turbo?
#3- Is there a comparable ratio for the intake side?
Thanks for the reply
Dan
FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
1. If the a/r is less than 1.0, the intake hole is larger. Which means in addition to extracing the exhaust's energy, it also accelerates the exhaust flow....so it spools very quickly at the cost of increased backpressure. If the a/r is larger than 1.0, the outlet is the larger hole. Supports increased flow with lower backpressure, but takes longer to get on speed = turbo lag.
2. Yes. Like in the case of the van turbo. The intake housing, compressor wheel, bearings, etc. are the exact same parts found in a stock truck turbo.
3. Yep, though I think all the stock or stock replacement PSD turbo's use a 1.0 intake.
2. Yes. Like in the case of the van turbo. The intake housing, compressor wheel, bearings, etc. are the exact same parts found in a stock truck turbo.
3. Yep, though I think all the stock or stock replacement PSD turbo's use a 1.0 intake.
Senior User
Joined: Dec 2004
Posts: 245
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From: Peshastin, Wa.
I went out and looked at my turbo after reading this thread. Mine says 1.10 A/R. I've heard you guys talk about 1.15 A/R and .84 A/R. I guess I don't fully understand the difference. What does this mean on mine? It is a Garrett.
