Let's Talk Turbos! - Page 2 - Subaru Enthusiasts Car Club of the Sierras

sperry · 2007-12-20, 01:17 PM

How hard is the intake rotation? Just a matter of bolting it on backwards, routing the throttle cable, and re-plumbing the cold side of the intercooler piping?

Double Phister · 2007-12-20, 01:21 PM

Quote:

Originally Posted by sperry

How hard is the intake rotation? Just a matter of bolting it on backwards, routing the throttle cable, and re-plumbing the cold side of the intercooler piping?

I think the biggest headache is dealing with the A/C but I don't think you have that problem

To bad you have to deal with the throttle cable though.

GST Mike · 2007-12-20, 01:28 PM

Throttle cable is just a bracket not such a big deal, also a bracket to relocate the alternator as if I recall you don't have AC.

Intercooler piping is not a huge job either just requires some mad TIG skillz y0..

Mike

knucklesplitter · 2007-12-20, 04:06 PM

I hate to argue the rotated intake manifold thing, especially with Mike advocating it... but how much IC tubing length does that save? What - 2 or 3 feet of 2.75"OD tubing? That's about 200 cubic inches (or about 1/8 cubic foot) of volume. How long does it take for a 400whp turbo to pressurize 1/8 of a cubic foot? That would be the gain in response. 400whp is say 500bhp which is about 500cfm or 8 cubic feet per second for a whopping 0.015 sec reduction in response just SWAGging it. I dunno - there must be something I don't understand. And running speed density (or BTM) there is not the lag time between MAF reading and induction into the cylinders either - that's the thing I don't like about FMIC and its long tubing along with draw-thru MAF.

GST Mike · 2007-12-20, 04:17 PM

Quote:

Originally Posted by knucklesplitter

I hate to argue the rotated intake manifold thing, especially with Mike advocating it... but how much IC tubing length does that save? What - 2 or 3 feet of 2.75"OD tubing? That's about 200 cubic inches (or about 1/8 cubic foot) of volume. How long does it take for a 400whp turbo to pressurize 1/8 of a cubic foot? That would be the gain in response. 400whp is say 500bhp which is about 500cfm or 8 cubic feet per second for a whopping 0.015 sec reduction in response just SWAGging it. I dunno - there must be something I don't understand. And running speed density (or BTM) there is not the lag time between MAF reading and induction into the cylinders either - that's the thing I don't like about FMIC and its long tubing along with draw-thru MAF.

I can only offer what we see on the dyno which on the same car shows to be a 200-300rpm difference depending on gear and load, also the transient throttle response is greatly improved. This is based off a GT30r running a Hydra tested same day.

Depends on what's worthwhile for people I guess, from a racing standpoint where rule restrictions are in place I'll typically take it where I can get it and with it being a none to costly or timely modification it just makes sense to make the efficiency where ever you can.

Mike

Dean · 2007-12-20, 04:21 PM

Quote:

Originally Posted by GST Mike

I can only offer what we see on the dyno which on the same car shows to be a 200-300rpm difference depending on gear and load, also the transient throttle response is greatly improved. This is based off a GT30r running a Hydra tested same day.

Depends on what's worthwhile for people I guess, from a racing standpoint where rule restrictions are in place I'll typically take it where I can get it and with it being a none to costly or timely modification it just makes sense to make the efficiency where ever you can.

Mike

I would guess it is due to fewer total degrees of tubing angle and thus turbulence in flow that makes the difference, not so much tubing length.

Double Phister · 2007-12-20, 04:35 PM

I think you have to factor in the fact that the whole system is feedback driven. If the turbo were simply spun at full speed by some outside force then you'd have a marginal improvement. But if you need to make exhaust to spin the turbo to make the boost to make more exhaust....I can see where there would be more benefit. Especially when going from no boost to full.

knucklesplitter · 2007-12-20, 04:42 PM

Quote:

Originally Posted by GST Mike

I can only offer what we see on the dyno which on the same car shows to be a 200-300rpm difference depending on gear and load, also the transient throttle response is greatly improved. This is based off a GT30r running a Hydra tested same day.

That's excellent info - no doubt. I just wish I understood the "why?" better. And is that both cold and hot sides changing when rotating the manifold?

knucklesplitter · 2007-12-20, 04:45 PM

Quote:

Originally Posted by R4ND0M_AX3

I think you have to factor in the fact that the whole system is feedback driven. If the turbo were simply spun at full speed by some outside force then you'd have a marginal improvement. But if you need to make exhaust to spin the turbo to make the boost to make more exhaust....I can see where there would be more benefit. Especially when going from no boost to full.

This is a good point.

GST Mike · 2007-12-20, 06:56 PM

Quote:

Originally Posted by Dean

I would guess it is due to fewer total degrees of tubing angle and thus turbulence in flow that makes the difference, not so much tubing length.

Yup no doubt, it's a total efficiency thing.

Mike

2007-12-20, 01:17 PM	#26
sperry The Doink Real Name: Scott Join Date: Nov 2002 Location: Portland, OR Posts: 20,335 Car: '09 OBXT, '02 WRX, '96 Miata Class: PDX/TT-6 The way out is through	How hard is the intake rotation? Just a matter of bolting it on backwards, routing the throttle cable, and re-plumbing the cold side of the intercooler piping? __________________ Is you is, or is you ain't, my con-stit-u-ints?

2007-12-20, 04:35 PM	#32
Double Phister EJ22 Join Date: Mar 2005 Location: Elk Grove, CA Posts: 450 Car: 2005 WRX STi "I'm sideways and in control... I look good."	I think you have to factor in the fact that the whole system is feedback driven. If the turbo were simply spun at full speed by some outside force then you'd have a marginal improvement. But if you need to make exhaust to spin the turbo to make the boost to make more exhaust....I can see where there would be more benefit. Especially when going from no boost to full. __________________ Dan - '05 Black WRX STi. My Mods

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2007-12-20, 01:28 PM	#28
GST Mike EJ22 Join Date: Apr 2005 Location: Hayward, CA Posts: 191 Car: Zee L Load, Efficiency, MAP etc etc etc	Throttle cable is just a bracket not such a big deal, also a bracket to relocate the alternator as if I recall you don't have AC. Intercooler piping is not a huge job either just requires some mad TIG skillz y0.. Mike

2007-12-20, 04:06 PM	#29
knucklesplitter EJ205 Real Name: Matt Taylor Join Date: Jun 2005 Location: Cousin-Fck, Carolina Posts: 1,475 Wish in one hand and sht in the other...	I hate to argue the rotated intake manifold thing, especially with Mike advocating it... but how much IC tubing length does that save? What - 2 or 3 feet of 2.75"OD tubing? That's about 200 cubic inches (or about 1/8 cubic foot) of volume. How long does it take for a 400whp turbo to pressurize 1/8 of a cubic foot? That would be the gain in response. 400whp is say 500bhp which is about 500cfm or 8 cubic feet per second for a whopping 0.015 sec reduction in response just SWAGging it. I dunno - there must be something I don't understand. And running speed density (or BTM) there is not the lag time between MAF reading and induction into the cylinders either - that's the thing I don't like about FMIC and its long tubing along with draw-thru MAF.