924Board.org

[-nick]

Hey folks,
I thought I'd start a thread to see when we're reaching our max boost. It's a good indication on how tight your plumbing is and how healthy your turbo is. Plus it can serve as a benchmark where to begin improving spool times and how the different stock turbos behave.

Please state: year and USA/RoW model, your max psi

Then do a pull in 3rd gear starting from a steady 2000rpm. And note at what rpm you get to your max boost.

For reference, I've got:
'79/80 RoW = 9.7-10.5 psi
'79-82 USA = 6.2-6.8 psi
'81/82 Row = 9-9.9 psi

ps - be safe!
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[emoore924]

80 931, USA, stock 4.10 turbo w/air-air i/c

If I remember right from the last dyno run:

Tops out at 14 psi right about 3k (RPM for full boost stays the same, lbs differ depending on adjustment...), drops back about one lb by about 6k.

[-nick]

Here is my latest data point (megasquirt logs are great!)

~8.5:1 compression
- 1980 USA turbo with Audi cold side housing - same compressor/turbine wheels, just no pop-off valve
- 951 intercooler
- custom intake
- cone filter

10.8 psi @ 2637 rpm

I still have lots of fuel & spark fine tuning, but it's a good start.
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[Rasta Monsta]

Shaggy Max (currently 10 PSI) achieved between 2500 & 2750.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[9xx]

-1982 Row model 177hp / 250 Nm torque
-stock, no modifications
-rebuilt turbo approx. 15 000km / 9400 miles ago

I just installed a boost gauge, it is VDO International series. Should be good quality and accurate. I removed the clock and put the boost gauge there instead. It's a similar set up as many of you have. Looks now like factory fitted. I like it better than the flashy looking tuning meters that are also available.


So, I get a full 0,65 BAR / 9.4 PSI around 3200-3300 rpm. Is it a bit too late? You guys seem to get full boost earlier. What do you think about this?

Also, my vacuum is showing -0.7 bar on idle with a warm engine. Is it good?

Turbo is charging the stock 0,65 BAR / 9.4 PSI to up to 6000 rpm. I do not want to rev it any harder. But this is a good sign, right?

I'd really appreciate you opinions here as I have just moved from 944 N/A's to the right side of the P-cars. 924's that is .
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Mikko

All gone: 931 '82 Alpine White, original option "220" G31 with LSD + 3 x 944

[9xx]

I continue my dark monoloque.

924RACR wrote in another thread:

"Yeah, even in 2nd I can feel the boost start to build once I pass 2000rpm. I seem to recall hearing that the Series I turbos were later and harder..."


I also read two old 924 Turbo articles that I have. First is about series I (170hp) and the other is about series II (177hp). The writer feels that the series I goes like rocket after +3000rpm whereas series II starts to accelerate after 2000rpm.

On my car I can hear turbo whistle after 2000 rpm but the boost comes after 3000rpm. You can feel this and it can be seen also from the boost gauge.

My turbo number is 5326 970 6020. Car feels fast after 3000rpm but I wonder if there is something I should check? Or does this all sound just normal?

EDIT: Here you can see the patient in question:

http://www.9xxfin.com/varikko/index.php?carid=26
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Mikko

All gone: 931 '82 Alpine White, original option "220" G31 with LSD + 3 x 944

[J1NX3D]

my cars been off the road for a while now, but from memory ( and with no boost guage) i could hear my RoW '80 start spooling audibly at 2700 and it starts pulling at around 3000, boosting hard at 3300+
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'86 944

[9xx]

[morghen]

9xx...i've got the same story here.

1982 S2 177BHP

i can feel the boost from 2000 RPM and in the 2000-3000 range i can hear the turbo spool up and after 2500-3000 its starting to realy put power down. in the 3500-5500 range it feels crazy ! specialy around 4000 RPM.

i dont have boost gauge yet...i want a VDO one to fit instead of the clock. anyone know any european sources?
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Supercharger and EFI kits
https://www.the924.com

[Raceboy]

Dunno if my turboed NA counts but just for the reference:

gets out of vacuum in 2000 rpm and hits full boost (14 psi) @ 3300 rpm all the way to redline 6800 rpm.

This is IHI KHF-5 turbo with 951-style exaust crossover pipe (turbo in the drivers side of the engine), 3" exaust, 951 IC and 2.5" intake plumbing.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[9xx]

Thank you for your comments Morghen & Raceboy.

[AGD931]

Same story here as all the other ROW S2's.

Starts pulling from 2k, steadily increases to just over 3k and then goes ballistic above that.

Arthur
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1981 931 S2
1990 E30 320i Cabrio
1979 Ford Capri Ghia