924Board.org

[Carrera RSR]

[morghen]

Mines fitted with a bit of hand pressing and a bit of rotation.
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Supercharger and EFI kits
https://www.the924.com

[WEASEL149]

[Raceboy]

Nice solution on the crank sensor!

Can't wait to hear the engine roar to life
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'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

[GeorgeV]

[WEASEL149]

[WEASEL149]

[Cedric]

There is an unused threaded hole under the intake manifold which is perfect for a knock sensor, works great for me.
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1980 924 Turbo
www.instagram.com/garagecedric/

[Raceboy]

Yes, I use that location too, so far works great.
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'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

[WEASEL149]

Thanks Cedric/Raceboy - that is the one I will use.
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1979 UK 932

[Shurick]

Since we are talking about about knock sensor... Does any one have an idea in what frequences pinging sounds occure? I need to set bandpass filter for HIP9011 detonation detector chip.
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WBR, Shurick
'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
https://www.instagram.com/ru_pacecar/

[WEASEL149]

[WEASEL149]

Continuing with Holset/HE221W discussion from Raceboy's thread:-



Morghen, if you only wish to run 1bar, there is a smaller Holset, the HE211W. This is available with 5cm turbine housing.
HE221W is found on 3.9L Cummins engines and nearly all the Holsets are designed to run at 1.5bar+.

My source told me that the 221 compressor compromises on efficiency a little for light weight and to get the extra map width. This is how it's able to outflow a lot of the HX30 wheels but builds boost quicker.

A 4x4 quattro managed 300awhp at 26psi with a crap chinese wastegate tapering off the boost.
This equates to roughly 370hp.
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1979 UK 932

[morghen]

Well that is strange isnt it, because if you plot 370hp and 26psi into that compressor map it is going to be outside the 50% efficiency isle by some amount. I've heard that people run these turbos away from their most efficient spot quite often but not outside the plotted efficiency isles.

I'm only lookging at this from the thermal point of view, it probably flows what you tell it to flow but this turbo will become a heat pump after 500CFM, thats 330hp. And even so, towards the end of the power delivery curve it will induce its most amount of heat. Empirically, i have no idea how much...it might be that this turbo's 50% efficiency is like older turbos 70% efficiency...its all down to numbers in the end and unless we are talking test laboratory conditions or one specific aplication with two different turbos its a wide guess which one heats up more than the other and when.

Here are the plots from Raceboy's thread, i deleted them there not to pollute his GTP car topic.

This is a bad plot of the 924 turbo over this map.
What's bad is that this turbo with its turbine will probably spool up faster and climb up towards the surge limit faster.


This is my setup, the K27 smallest trim compressor on the K26 turbine, spool-ul is actual behaviour in my particular setup.

_________________
Supercharger and EFI kits
https://www.the924.com

[WEASEL149]

Grr, hate typin' on phones...

The choke line on the map is the furthest point you can go to on the right. This lines falls approximately no lower than 59-60%. This is the lowest efficiency reading between surge and choke on the entire map.
Idea behind using a small(ish) turbo is to use the full map width to get max response with power.

K26 on stock CIS intake suffers around 1.62psi depression before the compressor.

Using the 221 on a stock 931 at 26psi:-

(26+14.7) / 13.08 = 3.11 pressure ratio.

13.08 comes from the pressure drop using stock intake.

3.11 puts you right on the widest part of the map which gives 378hp theoretical max power. (37.8lb/min max compressor flow).

60% efficiency is fine with charge-cooling especially at the extremes.

Oh yeah, don't worry about surge. The compressor cover has anti-surge (map width enhancement) slots which also happen to make awesome turbo sound effects
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1979 UK 932