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931 (Woody) project
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Mike9311  



Joined: 14 Dec 2004
Posts: 878
Location: Chicago-ish

PostPosted: Mon May 18, 2020 6:16 am    Post subject: Reply with quote

jacobroufa wrote:
Ok, I was going to try to reply to all individually but apparently more posts wound up in the thread...

Steve & Mike -- So with an S1 I have the 2664 wheel and a 4.10 size housing -- the 2470 wheel is a different shape and 6.10 is a bigger housing? Does that mean it has capacity to build more boost later on? I have read a bit about the different housing/wheel combinations, and understand very little about what is interchangeable and what the effects of each will be. Is there an ideal combination? It seems like the 2664 are not available and so I should just hang on to mine.. But there's also e.g. K26 vs K27 -- so many different parts and variations that I see people using. What is incentive to change over to a different housing or compressor wheel and how will I know when I hit the point where I need to? To pile on here, what is the big difference between 924 and 944 turbos -- ours are just oil cooled and the 951 got a watercooled turbo? Does this upgrade make sense at some point?

I know these questions are probably way more disparate than I am making them out to be, but I grouped them all together because that's the current pithy state of my understanding...


To simplify in your case and you wanting to run this summer. The US S1 2664 is a good compressor that you will enjoy. Over here in the USA we won't run into the 2470 unless by weird chance. You will find more 81-82 smaller 2660 compressors from the US S2. DONT switch to a 2660. The small diameter blade section (inducer) is 4mm smaller. You already have a compressor larger than a GT.

Morghen/Steve K27 mod seems to the killer upgrade but I would wait while you dial in everything else. Stage the upgrades as you can.

The hot side US 4.10 (found also in Europe I guess because they had a lot) is small and lets you spool faster. The rare 6.10 Euro RoW hot side housing is larger and will cause slower spooling. It helps get rid of heat and generate more power at the top end so eventually you will likely want one. I watch German Ebay constantly and they are hard to come by. Its why I have been going through the process of making them. Hopefulley soon. Don't worry if you stick with the 2664/4.10 US S1 for now. Intercooled and a small boost increase will be a smile generator

The Standard 944Turbo K26 compressor is almost identical to the US S1 except the Exducer (large diameter) blade tip height in lower. The 944Turbo S has the k26/8 which has a larger compressor but your S1 housing won't work without machining.

For reference

6.10 Left vs US 4.10 Right



US S1 2664 Compressor



US S1 2664 Left / Morghen's 2470 / Aftermarket Billet 2660... see how big the 2664 is? Ignoring how tall the billet wheel is, see how the upper tip diameter is smaller (distance across at top)? The 2664 is a decent wheel



US S2 2660 and also Carrera GT compressor. The 2664 is larger across top (inducer)



Beat up 2660 wheel in 2664 housing. This shows how much larger your 2664 inducer opening is.

_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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Mike9311  



Joined: 14 Dec 2004
Posts: 878
Location: Chicago-ish

PostPosted: Mon May 18, 2020 6:19 am    Post subject: Reply with quote

jacobroufa wrote:
Oh here is the rabbit hole...

So Mike! Can I twist your arm for a custom part or two? Once I'm ready, I mean -- it'll be awhile before I can swing the Ideola intercooler and everything necessary to install -- I will specifically be on the lookout for the lower charge tube to intercooler elbow that you made:

http://www.924board.org/viewtopic.php?p=391740#391740

---

I can't stop reading about all the possibilities with this car. My head is reeling.


You can I am about to work on it for the Ideola CS. Its something that a few have asked about already so I really need to clean up the code and make a few.
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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jacobroufa  



Joined: 18 Nov 2016
Posts: 286
Location: Rockford, IL

PostPosted: Mon May 18, 2020 7:20 am    Post subject: Reply with quote

Awesome

I did see most of that information from your 4.10 vs 6.10 thread, but it is nice to get the tl;dr here -- spool later and more boost.

That is awesome to hear about the parts. I think this is the best time to be a 931 enthusiast, despite our low numbers. There's a level of polish and commitment to the aftermarket that, despite not having a ton of options, assures that we will have the utmost performance.
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1981 Porsche 924 Weissach
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2039
Location: MI

PostPosted: Mon May 18, 2020 8:17 am    Post subject: Reply with quote

Carrera RSR wrote:
Fasteddie313 wrote:
Stock fuel system is good to 1 bar no problem.. According to my tests it will spray like 330 HP worth of fuel, so I figure it would be good to 250HP or so conservatively..
I should have ran longer/harder on my stock fuel system, but I fell in love with the V8 fuel distributor thing, so I don't have any logs of te stock fuel system...


Internet and forum myth suggested stock CIS max'd out at 250bhp. Not found any validation of that. Curious how you calculated 330hp worth?


Fasteddie313 wrote:
The results are in..

All of these numbers are with the airplate at 100% travel and full flow, per injector..

103 psi system pressure

Frequency valve full closed/unplugged
76.5 grams in 30 sec

Frequency valve plugged in and running as default (can measure actual duty cycle later)
102.53 grams in 30 sec

Frequency valve full open, +12v constant
163.97 grams in 30 sec


Frequency valve full open, +12v constant @ 89 psi system pressure (removed my bump shim)
159.53 grams in 30 sec



reanimotion wrote:

1 CC of fuel is 748.9milligrams

so

164 grams per 30 seconds = 438 cc/min or 41.7 lbs/hr

good for approximately 330HP at 0.5 bsfc


I timed spraying fuel at full blast and weighed it..

This was a US FD with the frequency valve wide open..
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2039
Location: MI

PostPosted: Mon May 18, 2020 8:33 am    Post subject: Reply with quote

jacobroufa wrote:
So did you pull apart the turbo in the middle and offset the compressor housing 180░ or something?


The first time I did it I just installed an Audi 2664 housing onto my 2664 turbo, and pointed it down..
Then I swapped to a 951 compressor..

jacobroufa wrote:
Eddie what's the deal with your air box? Was that a necessary modification because of your V8 fuel distributor?


Yeah... Well I suppose it could have been done other ways..

I wanted to keep the stock airbox, so I cut up an old lawnmower hood and hammered it out to make it fit the big FD and to the stock airbox, and welded it up..
https://www.youtube.com/watch?v=B-M9O5LjgP4

I painted it but a bit of gas got on it, the paint did not like that, and now it's a bit rusty on the outside, but I don't mind too much and it'll be easy to repaint it whenever..


jacobroufa wrote:
Ok, Cedric & Eddie... What is your compressor housing changed out to in order to get it to re-index properly and face the outlet downward? And how are you now managing extra pressure build-up? It looks like you have added a BOV to the upper charge tube, Eddie, is that correct?

I have an incredible amount to read and try to understand here, but I gather that modification of turning the housing cannot be done with our stock compressor housing because of the built in recirculation valve.


Yes changed the housing, or just use about any other compressor without the recirc valve in it..

Yes I put my BOV off the upper charge tube there, Cedric put his underneath by the IC, which I like better..

The intake for the stock comp housing is angled up toward the FD air meter, so turning it would also point its intake at the ground..

It might be possible to modify one to make it work but nah.. I never even tried to see what it would look/fit like upside down..
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2039
Location: MI

PostPosted: Mon May 18, 2020 8:36 am    Post subject: Reply with quote

CÚdric wrote:

Here's that Facebook post, maybe i should make a big thread on here instead. I don't like Facebook for stuff like this anyway. Your install is there aswell, in the comments.

https://m.facebook.com/story/graphql_permalink/?graphql_id=UzpfSTEwMDAwMDY2OTEyNDY4MTpWSzoxNjA1NDI2MTAyOTY3NDIw


Do both?
FB might bring in some new blood?

I'll have to check it out..
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Mike9311  



Joined: 14 Dec 2004
Posts: 878
Location: Chicago-ish

PostPosted: Mon May 18, 2020 9:14 am    Post subject: Reply with quote

Fasteddie313 wrote:
CÚdric wrote:

Here's that Facebook post, maybe i should make a big thread on here instead. I don't like Facebook for stuff like this anyway. Your install is there aswell, in the comments.

https://m.facebook.com/story/graphql_permalink/?graphql_id=UzpfSTEwMDAwMDY2OTEyNDY4MTpWSzoxNjA1NDI2MTAyOTY3NDIw


Do both?
FB might bring in some new blood?

I'll have to check it out..


Whats funny is my Nephew is totally about the Facebook group while I am on "the Forum" like this is the only 924 Forum in existence
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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jacobroufa  



Joined: 18 Nov 2016
Posts: 286
Location: Rockford, IL

PostPosted: Mon May 18, 2020 11:27 am    Post subject: Reply with quote

Fasteddie313 wrote:
The first time I did it I just installed an Audi 2664 housing onto my 2664 turbo, and pointed it down..
Then I swapped to a 951 compressor..


Nice did you swap the bearing housing too?

Fasteddie313 wrote:
I wanted to keep the stock airbox, so I cut up an old lawnmower hood and hammered it out to make it fit the big FD and to the stock airbox, and welded it up..
https://www.youtube.com/watch?v=B-M9O5LjgP4


I saw this that's why I asked; I was mostly just wondering if the stock boot could not be used. I didn't realize the distributor opening was bigger than the 931. I think at some point today though I saw this picture of the GTS engine bay and understand what you were doing. Looks like you did exactly what they did.



Fasteddie313 wrote:
Yes changed the housing, or just use about any other compressor without the recirc valve in it..

Yes I put my BOV off the upper charge tube there, Cedric put his underneath by the IC, which I like better..


Cool. I need to dig through more threads for his build also. I wish so many old image links were also not crap -- it is hard to tell what's going on when posts reference pictures that are not there anymore.

Mike9311 wrote:
I am on "the Forum" like this is the only 924 Forum in existence


It isn't?
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2010
Location: Somerset, UK

PostPosted: Mon May 18, 2020 6:42 pm    Post subject: Reply with quote

jacobroufa wrote:

I saw this that's why I asked; I was mostly just wondering if the stock boot could not be used. I didn't realize the distributor opening was bigger than the 931. I think at some point today though I saw this picture of the GTS engine bay and understand what you were doing. Looks like you did exactly what they did.





Thats not a exactly a GTS...... It is a race prepared Carrera GT upgraded to 'GTS spec' by Mittelmotor. Easily confused and to most it looks the same, but has some differences in the details. The fuel system, airbox and intake are MM's remanufactured parts.

Heres a genuine one to play 'spot the difference' with


_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2010
Location: Somerset, UK

PostPosted: Mon May 18, 2020 7:08 pm    Post subject: Reply with quote

Fasteddie313 wrote:
Carrera RSR wrote:
Fasteddie313 wrote:
Stock fuel system is good to 1 bar no problem.. According to my tests it will spray like 330 HP worth of fuel, so I figure it would be good to 250HP or so conservatively..
I should have ran longer/harder on my stock fuel system, but I fell in love with the V8 fuel distributor thing, so I don't have any logs of te stock fuel system...


Internet and forum myth suggested stock CIS max'd out at 250bhp. Not found any validation of that. Curious how you calculated 330hp worth?


Fasteddie313 wrote:
The results are in..

All of these numbers are with the airplate at 100% travel and full flow, per injector..

103 psi system pressure

Frequency valve full closed/unplugged
76.5 grams in 30 sec

Frequency valve plugged in and running as default (can measure actual duty cycle later)
102.53 grams in 30 sec

Frequency valve full open, +12v constant
163.97 grams in 30 sec


Frequency valve full open, +12v constant @ 89 psi system pressure (removed my bump shim)
159.53 grams in 30 sec



reanimotion wrote:

1 CC of fuel is 748.9milligrams

so

164 grams per 30 seconds = 438 cc/min or 41.7 lbs/hr

good for approximately 330HP at 0.5 bsfc


I timed spraying fuel at full blast and weighed it..

This was a US FD with the frequency valve wide open..


Thank you for the info. Assume I missed this in your thread. Lots to read. Are these figures for the new V8 head or the original US turbo fuel dizzy?

The figures I have for turbo heads are
Bosch 0438 100 256 flows 256cc/min (series 1 Row)
Bosch 0438 100 096 flows 270cc/min (series 2 Row)
My modified 096 dizzy now flows 365cc/min
Motorsport spec V8 dizzy on Carrera GTS flows 450cc/min

Whilst the GTS was sold at 245 and 275bhp flavours, they were prepared ready for more power well into the 300's.

Just to check, you refer to 'frequency valve' is this the cold start injector? I've considered firing it at the top end but in the stock position its only likely to help cylinders #3 and 4 as it will be fitting the incoming boosted air to get to #1 and 2.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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Mike9311  



Joined: 14 Dec 2004
Posts: 878
Location: Chicago-ish

PostPosted: Mon May 18, 2020 11:34 pm    Post subject: Reply with quote

Quote:
Just to check, you refer to 'frequency valve' is this the cold start injector? I've considered firing it at the top end but in the stock position its only likely to help cylinders #3 and 4 as it will be fitting the incoming boosted air to get to #1 and 2.


Like the Miller Woods Turbo Group Fueler
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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ideola  



Joined: 01 Oct 2004
Posts: 15506
Location: Woodstock IL

PostPosted: Mon May 18, 2020 11:39 pm    Post subject: Reply with quote

The frequency valve is only on Lambda-equipped cars. It is used by the Lambda box to manage fuel enrichment at WOT. @Fifty50Plus used it with an electronic controller to manipulate higher fuel delivery on his NA SCCA ITB car, so it can be used successfully for this purpose. However, it certainly has limitations on turbo cars, as I think the duty cycle will max out pretty quickly. You might get some marginal increase in fuel delivery, but not sure it would be sufficient for the kinds of boost levels discussed here.

I am still baffled, however, at the assertion that fuel flow is the problem. On all of the cars that I increased boost on, I had problems with overfueling at high boost, not the other way round.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2039
Location: MI

PostPosted: Tue May 19, 2020 1:35 am    Post subject: Reply with quote

Carrera RSR wrote:

Are these figures for the new V8 head or the original US turbo fuel dizzy?

The figures I have for turbo heads are
Bosch 0438 100 256 flows 256cc/min (series 1 Row)
Bosch 0438 100 096 flows 270cc/min (series 2 Row)
My modified 096 dizzy now flows 365cc/min
Motorsport spec V8 dizzy on Carrera GTS flows 450cc/min


For the US 931 FD I got 438 cc/min with the "frequency valve" full open (constant 12 volts)..

ideola wrote:
The frequency valve is only on Lambda-equipped cars. It is used by the Lambda box to manage fuel enrichment at WOT. @Fifty50Plus used it with an electronic controller to manipulate higher fuel delivery on his NA SCCA ITB car, so it can be used successfully for this purpose. However, it certainly has limitations on turbo cars, as I think the duty cycle will max out pretty quickly. You might get some marginal increase in fuel delivery, but not sure it would be sufficient for the kinds of boost levels discussed here.

I am still baffled, however, at the assertion that fuel flow is the problem. On all of the cars that I increased boost on, I had problems with overfueling at high boost, not the other way round.


My results were..

Frequency valve full closed/unplugged
76.5 grams in 30 sec

Frequency valve plugged in and running as default (can measure actual duty cycle later)
102.53 grams in 30 sec

Frequency valve full open, +12v constant
163.97 grams in 30 sec

So I find that the difference between the FV full closed vs full open is more than double fuel flow to the injectors..

With FrankenCIS firmware (free) you can control the FV from a microsquirt directly... And I bet it'd work perty dern gerd..


Basically their are 3 versions of K-Jet..

K-Jet basic - Euro 924 including GTS and 928 - AFR controled by aircone shape and WUR

K-Jet Lambda - US 924 - AFR controled by aircone shape, WUR, and FD diaphragm differential pressure via the Frequency Valve

KE-Jet - Mercedes up to the early 1990's - No WUR, Linear aircone, AFR controlled mostly by FD diaphragm differential pressure via the DPR which I think is "Digital Pressure Regulator" instead of a frequency valve..



See where that pic says "differential pressure valve"..

K-Jet Basic - this valve is only set by spring pressure

K-Jet Lambda - this valve has the same springs but also has a pressure bleed off from under the diaphragm "lower chamber", under the springs, to reduce fuel pressure in the lower chamber, letting the diaphragm flex down more opening up a bigger path for fuel to flow to the injectors..
This is what the Lambda system does with the FV which is basically an EFI fuel injector the computer can tell how much fuel/pressure to leak out of the lower chambers..

KE-Jet - throws the WUR and Frequency Valve away completely and does most of it's control with this lower differential pressure with a digital valve managed by a computer.. The DPR.. Which can close off the lower chamber to the return circuit, increasing the lower chamber pressure, and basically closing the output to the injectors, or it can dump all the lower chamber pressure to the return circuit to open the injectors more and flow wayyy too much fuel for any given airplate position..


With my KE-Jet FD, with the computer, I can tell it to completely cut fuel at any airplate position, and it will also drown my engine with fuel at any airplate position if I tell it to..
Complete control of how much fuel it sprays by computer almost no matter the airplate position..
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1102
Location: Washington DC area

PostPosted: Tue May 19, 2020 2:51 am    Post subject: Reply with quote

The lambda box uses the narrow band CO reading to drive the freq valve. We replaced it with a wide band system (Inovate) that also presents the reading on the dash and stores it for later review. We used a series of resistors added to the lambda to generate around 12.8 CO. Dyno tests showed that was the best power and temp setting for the NA engine with 1/2 point higher compression and stock camshaft (SCCA rules). We are probably running the freq valve at about 80% at WOT.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
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Mike9311  



Joined: 14 Dec 2004
Posts: 878
Location: Chicago-ish

PostPosted: Tue May 19, 2020 5:05 am    Post subject: Reply with quote

by now this is the wrong place to put this but I just want to show since there are many eyes on this thread

Here is the one difference between a 944 Turbo K26/6 Compressor Wheel and the US S1 924 Turbo K26....both are 2664 compressor wheels but the exducer tip height is different with the 944 on the left is lower in height. Can't just throw a 944 wheel "6" wheel into a US S1 2664 housing. They are the same height at the top of the blades. Picture doesn't show this


_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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