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baldwin
Joined: 02 Nov 2002
Posts: 113
Location: The Hague, The Netherlands
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 Posted: Sun Sep 21, 2008 8:17 pm Post subject: 933 project - dyno results |
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My 933 project has been on the dyno, and the result was a disappointing 92kW at the wheels.
Engine setup:
- 931 head, stock except for camshaft
- CatCams camshaft http://www.xs4all.nl/~bjong/porsche/933/engine/docs/catcams-5220008.jpg
- JE Pistons 11:1 pistons, compression test showed 16.5 17.2 16.8 16.3 bar http://www.xs4all.nl/~bjong/porsche/933/engine/mannessen/p1010003.jpg
- 2.25" exhaust, 4-1 header
- Emerald electronic injection and ignition
- stock 931 intake manifold
- Weber/Redline throttle body
- stock rubber intake boot on throttle body
- cone air filter
I'm starting to think that after the head, the intake becomes the limiting factor when you reach 160hp (at the flywheel that is). Raceboy hit 120rwhp with a 931 head and decking the block 2mm, there was a German guy who did basically the same as raceboy and got 160hp at the flywheel with a ported 924 head (unconfirmed Internet story), and now me.
This can also explain some outrageous hp claims from guys with ported heads and carbs...
So the next stage for me are ITB's. It's a shame martijnus had his accident before he could fire up his engine. Couldn't you wait just one week? 
Edit: I said "stock manifold", but I meant "stock 931 manifold". 924 intake manifold won't fit 931 head.
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924 parts, http://verkopers.marktplaats.nl/10266983
'98 Volvo 940 LPT Estate
Last edited by baldwin on Mon Sep 22, 2008 12:57 am; edited 1 time in total |
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Raceboy
Joined: 01 Mar 2004
Posts: 2327
Location: Estonia, Europe
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| Posted: Sun Sep 21, 2008 9:30 pm Post subject: |
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Yes, ITB's should be definitely added.
But either way, numbers are not disappointing, but rather what should be expected 
Very nice project also!
_________________
'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.
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Mon Sep 22, 2008 1:16 am Post subject: |
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I wonder if a S2 931 mani would help you?
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Mon Sep 22, 2008 2:03 am Post subject: |
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why dissapointing? 160 from a 2 liter NA...thats good for a home prepped car. Hondas get 200 but with way higher RPM and the VVT thing...with ITB and a bit more tuning here and there you can get another 10 to 15 and then you're done with the NA...oh wait...you could just NOS it....
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Supercharger and EFI kits
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Raceboy
Joined: 01 Mar 2004
Posts: 2327
Location: Estonia, Europe
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| Posted: Mon Sep 22, 2008 2:30 am Post subject: |
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| Rasta Monsta wrote: | | I wonder if a S2 931 mani would help you? |
Only difference is just the throttle opening and that is actually smaller than S1 dual-butterfly throttle body.
_________________
'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 |
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Mon Sep 22, 2008 2:31 am Post subject: |
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I think those results are pretty good.
I have known people who run 11:1 compression on larger engines - aren't you a little concerned about detonation? 11:1 compression can make for a helluva lot of heat. Maybe it's a power robber?
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1980 924 turbo, MSD, Meth. Inj, otherwise stock. |
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baldwin
Joined: 02 Nov 2002
Posts: 113
Location: The Hague, The Netherlands
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| Posted: Mon Sep 22, 2008 2:59 am Post subject: |
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| Raceboy wrote: | | Rasta Monsta wrote: | | I wonder if a S2 931 mani would help you? |
Only difference is just the throttle opening and that is actually smaller than S1 dual-butterfly throttle body. |
Ah ok, I was wondering about that. Scratch any type of 931 manifold then.
| tuurbo wrote: | | I have known people who run 11:1 compression on V8s - aren't you a little concerned about detonation? 11:1 compression can make for a helluva lot of heat. Maybe it's a power robber? |
11:1 is high, and I use 98RON, but the ignition map shows normal values.
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924 parts, http://verkopers.marktplaats.nl/10266983
'98 Volvo 940 LPT Estate |
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Mon Sep 22, 2008 4:34 am Post subject: |
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K 98RON is way high enough I would guess - so normal values for IAT? Or A/F? Knock sensor? That sort of thing you mean?
So I don't have one of these ignition systems - can't you push it or adjust it so that the ignition maximizes the power more to your liking?
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1980 924 turbo, MSD, Meth. Inj, otherwise stock. |
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baldwin
Joined: 02 Nov 2002
Posts: 113
Location: The Hague, The Netherlands
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| Posted: Mon Sep 22, 2008 4:53 am Post subject: |
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| tuurbo wrote: | | So I don't have one of these ignition systems - can't you push it or adjust it so that the ignition maximizes the power more to your liking? |
I'm afraid the engine is running as best as it can. The Innovate LC-1 in combination with a wideband lambda sensor is telling me afr's are perfect. Management is running closed-loop when cruising, open loop at WOT, nice acceleration enrichment, everything is spot on. Mapping was done on the dyno with the help of knock sensors, and that's it.
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924 parts, http://verkopers.marktplaats.nl/10266983
'98 Volvo 940 LPT Estate |
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Raceboy
Joined: 01 Mar 2004
Posts: 2327
Location: Estonia, Europe
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| Posted: Mon Sep 22, 2008 5:44 am Post subject: |
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How much advance are you running at maximum load (100 kPA) and 3000-7000 rpm?
Perhaps your engine is knock limited, not MBT limited? Did you have to back off timing due to detonation and lose torque at specific loadsite?
_________________
'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 |
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Mon Sep 22, 2008 5:51 am Post subject: |
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Ok thanks that answers my question. Good luck with it - post pics when you get the ITBs set up. Doing stuff like this with NA engines is very cool.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock. |
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Martijnus
Joined: 29 Dec 2006
Posts: 2019
Location: Netherlands
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| Posted: Mon Sep 22, 2008 6:24 am Post subject: |
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how do you know AFR is perfect.
That's the one thing I still don't get... in MS I need to configure an AFR table...but how the hell do you know which AFR values correspond with the table cells with a particular engine...
what's the 'right' afr for every rpm/map?
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)
924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment |
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Mon Sep 22, 2008 6:43 am Post subject: |
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Martijnus - good question - I'm not sure - I think on my car it has the most power around 12 to 13.5 at full boost.
Would you look at your HP across a range of AF settings, and choose the AF setting that gave you the most HP on the dyno?
_________________
1980 924 turbo, MSD, Meth. Inj, otherwise stock.
Last edited by tuurbo on Mon Sep 22, 2008 6:50 am; edited 1 time in total |
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baldwin
Joined: 02 Nov 2002
Posts: 113
Location: The Hague, The Netherlands
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| Posted: Mon Sep 22, 2008 6:48 am Post subject: |
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| Raceboy wrote: | How much advance are you running at maximum load (100 kPA) and 3000-7000 rpm?
Perhaps your engine is knock limited, not MBT limited? Did you have to back off timing due to detonation and lose torque at specific loadsite? |
This is my ignition map:
No anomalies I think, no strange dips anywhere.
Ummm... What does MBT mean?
| martijnus wrote: | That's the one thing I still don't get... in MS I need to configure an AFR table...but how the hell do you know which AFR values correspond with the table cells with a particular engine...
what's the 'right' afr for every rpm/map? |
At cruising conditions, you want to be close to 14.7, at performance conditions, you want to drop to... I dunno 12.x? Perhaps this is a good starting point (it's from my mapping)
_________________
924 parts, http://verkopers.marktplaats.nl/10266983
'98 Volvo 940 LPT Estate
Last edited by baldwin on Mon Sep 22, 2008 6:58 am; edited 1 time in total |
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Martijnus
Joined: 29 Dec 2006
Posts: 2019
Location: Netherlands
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| Posted: Mon Sep 22, 2008 6:56 am Post subject: |
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| tuurbo wrote: | | Martijnus - Just guessing: Assuming the AF has a range that's ok, I'd take the leanest you can make it and still be safely with enough fuel - at the lean end of the safe range. Wouldn't that maximize hp? |
that way you're just moving the problem to which values are 'safe'...
so if I'm under full load... how do I establish the right AFR... just go as lean as possible until the engine almost dies? I'm quite sure this is far from optimal.
I've come up with a strange algorithm which could do it...but it's so stupid that it wouldn't work, unless you have a dyno to let it tune every cell separately and if I had a dyno, all my troubles would be solved.
the optimal afr is the one which outputs the most power, so on the dyno you could get it as it gets.
I let MS create a AFR table given some engine specs (which aren't complete because I don't know the map values at top torque and hp)...can't do much more
edit: thanks baldwin! I seriously am thinking about a subforum for EFI with some kind of database in which everyone could post their tables... AFR should be the same on every engine...or at least more the same than VE or ignition (cause that's depending on the injectors used etc)..
our engines should in theory have quite the same AFR table.
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)
924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment |
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