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how did he compensate for the body damage??

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Old 01-24-2009, 04:30 PM
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Body Damage

Hasn't yet, but says he will.
I'm thinking I need to get my 3k back for the install and call it even.
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'77 Ice Green 911s Targa that's almost a 930
Old 01-24-2009, 04:41 PM
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Quote:
Originally Posted by parasailsam View Post
Dave,
Looks like I don't have a second fuel pump, but Spuggy says he runs ok on mild turbo upgrade...
Yup, single 'S' factory pump (original AFAIK) made good flow/pressure figures and AFR's were fine flat out when checked by PO, and when dyno'd by me. I think it's a myth that you need two fuel pumps.

(Later fitted an 044 motorsport pump because the original pump was noisy/just for the heck of it/cheap insurance when I uprated the turbo. The brand new Bosch 044 pump made exactly the same noise as the old factory pump.)

Flow and pressure are the only things that count. What system pressure does it make? How much does it flow?

Quote:
Yes, the car runs well up to 10psi where the boost limit is, then it sputters and the boost guage goes up and down rapidly from 5 to 15 as it cuts out, sputters, looses power and basicly worries the heck out of me.
Shouldn't the wastergate limit the boost a 10psi but not dump all the boost?
Yes, the wastegate should regulate the boost at the maximum setting.

The factory two-pump setup cuts the rear pump when the overboost sensor triggers (range 1.1-1.4 bar, IIRC), and folks here describe it as like hitting a wall (head bouncing off the steering wheel effect). Rear pump failure is "limp home" mode.

I don't have one fitted, and my car doesn't overboost anyway. Can't tell you how it might behave with a single pump - but the symptoms might well be different.

Are you sure you have an overboost sensor? And the relay? What's it wired to - the front pump circuit?

Sure you're not hitting the rev limiter?

Are you running the 930 CDI box (with a built-in rev limiter) or a rev limiting distributor rotor?

Quote:
I don't know never having had a turbo before.

The mechanic who worked on it said I should get 2 or 4 prong plugs and a high enery ignition system... would that really help?
I'm pretty sure the stock 930's didn't have that stuff in the late 70's.
They ran single prong Bosch Platinum plugs from the factory. They're very, very, cold (so they don't melt your pistons) - but they don't foul in town.

The Bosch CDI ignition IS a high-energy ignition system. You don't want to get a belt from that sucker.
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'77 S with '78 930 power and a few other things.
Old 01-24-2009, 05:09 PM
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Quote:
Originally Posted by parasailsam View Post
Ok,
So my 911 should have the 2 fuel pumps if it has one in the engine bay right?
The second fuel pump - the rear one - would be mounted on a bracket underneath the car, by the transmission. On a stock 930.

Quote:
I'm calling the can below the deck lid hinge in the last pic the rear fuel pump.
Am I right?
The outermost one (next to the CDI) looks like a stock fuel filter to me, and the one slightly closer to the firewall looks like a stock fuel accumulator.

Quote:
And Spuggy,
What readings should I be looking for when I get the sensor to read the AFR's?
Thanks guys
That's the subject of much controversy. The factory apparently said (at the time) "for a 930, anything that doesn't have unburnt fuel running out of the exhaust pipe isn't too rich". That's a quote from a factory-trained 930 guy - in fact, 930 tech secretary for the UK POC.

Times have changed. That's no longer how you set up 930's. Costs 30-40 HP in the midrange, apart from anything else (like contaminating the oil with the excess gas).

For best power, and good engine safety, most people would be very happy to maintain low twelves - say 12.2 or so - under boost all the way to redline.

In practice, most unmodified CIS fuel systems on 930's dump far too much fuel into the system (10's or lower) as soon as boost comes on, and then cannot maintain AFR's to safe levels as RPM's rise.

A Brian Leaske adjustable WUR can help dramatically here - as it lets you tune the onset PSI and amount of boost enrichment to a certain extent.

Sam, you say you have a '79 3.0 SC motor in there, but you don't mention any changes to the pistons.

What compression ratio are you running that motor at? What ignition timing?
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'77 S with '78 930 power and a few other things.
Old 01-24-2009, 05:28 PM
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To me, if the car runs well up to 10 PSI (assumption not yet clarified), the overall system is probably in good shape. Once boost drops back below 10 PSI is everything good again?

It sounds like at 10 PSI either things go lean (i.e. engine consuming unmetered air, maybe due to the way the wastegate plumbing is set up?) or something is happening to ignition. Short of putting in a wide-band O2 sensor, how about taking the car to a dyno so you can see if it's going lean?
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Old 01-24-2009, 07:09 PM
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Quote:
Originally Posted by parasailsam View Post
How, where do I locate the switch if I have one?
Thanks,
Sam
Sam,
The overboost sensor switch would be located on the charge side of the induction. Probably a single wire. If you can't find it, I would ask the mechanic who installed this system, if he incorporated it. If he did, maybe he's using it to control the ignition instead of the fuel pumps as the factory did. Also, if he did install one, how did he wire it, ignition or fuel pumps?
The symptoms of an overboost sensor switch(fuel pump control) activation is like running out of power suddenly at speed. It will sputter and die until the engine returns to lower boost pressures and then run normal like nothing happened.

Also, can you photgraph or diagram how the wastegate is setup? What type of headers are you using?

Off topic, but are you using stock 3.0 pistons in this setup? What's the compression ratio?
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'85 930 Factory Special Wishes Flachbau
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Old 01-25-2009, 05:01 AM
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OK, that's some more info.

If I understand this correctly, you used 930 3.0L non-intercooled turbo, CIS and intake and bolted this onto N/A 3.0L SC engine?? Which engine and what compression?



First: CIS works with fairly high system pressure. When used with turbocharger fuel demand can be quite high, thus 930 needs two pumps in series to satisfy fueling needs. Using a single SC pump (or even worse, a single EFI pump tailored to lower fuel pressure) is probably not safe for anything but mild boost.

Further on, lower wastegate port should be subjected to boos pressure. Top portion can be left open to atmosphere. Stock wastegate spring usually defaults to 0.7 bar of boost.

I would start with adding second fuel pump, in order to have fuel delivery squared off. Then I would check for boost leaks (check plastic intake spacers for cracks and leaks). After that is done, I would do a dyno run or a pull with WBO2 logger in order to check for leaning or overrich condition (if there is a boost leak present).

If AFR's are OK and engine still keeps cutting out, I would check the ignition (beggnining with plugs and coil). Also, depending on C/R used, you might want to lower a boost a tad...

Regards,
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Old 01-25-2009, 06:04 AM
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Quote:
Originally Posted by beepbeep View Post
First: CIS works with fairly high system pressure. When used with turbocharger fuel demand can be quite high,
No question.

Quote:
thus 930 needs two pumps in series to satisfy fueling needs. Using a single SC pump (or even worse, a single EFI pump tailored to lower fuel pressure) is probably not safe for anything but mild boost.
With respect, this doesn't necessarily follow from the earlier statement, in my limited (sample size == 1) experience.

The AFR's sustained on a mild 3.3 930/60 by the single, stock, possibly-original (in which case it would have had 237,000+ miles on it) factory pump in my '77 were assessed by the PO.

With an LM-1 at speeds up to and including the rev-limited top speed. Multiple runs. They checked out.

He tracked the car. More than once. He drove the car on 1,500 mile road trips, including through the desert. More than once. Didn't blow up.

I took the car to a reputable 930/MOTEC tuner to have AFR's checked. They were not a concern and nothing was adjusted. Car made 310 FWHP.

I'm not saying AFR's, fuel flow and fuel pressure (and ignition) aren't critical.

I'm saying you don't need two pumps simply because the factory fitted two. What the pump delivers to the fuel system - flow & pressure - and the AFR's "seen" by the motor - is what matters.
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Old 01-25-2009, 09:13 AM
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Troy N,
Yes the sys works fine up to 10psi, then goes to the toilet as described. Once I take my foot off the accelerator it runs fine again.

Goran,

["If I understand this correctly, you used 930 3.0L non-intercooled turbo, CIS and intake and bolted this onto N/A 3.0L SC engine?? Which engine and what compression?"]

You have it right. The 2.7 L motor was replaced with a 1983 3.0 L by Reid Vann in ST. Louis by previous owner in 12/03. Wiring and ECU were changed at that time to match '83 motor.
The '83 engine, I belive is completely stock, so specs would be to norm for that motor I think.
The 930 part are from a late 70's early 80's CIS
All gaskets/boots are new for this buid on the turbo/intake portion. Car ran very well prior to turbo addition as far as ignition goes. Was mainained by Reid Vann during previous ownership.
I believe stock wastegate was indicated at .8bar spring? Sound right?
The machanic said he shaved that a bit too to lower boost.

Dave,
The headers are GSF with heat boxes. I don't know what the comp. ration is or what timing is now set at, but will find them both out today.
The mechanic fooled with air/fuel mixture and timing ( he says ) for a long time trying to get it to run right.
Wastegate from well

vent side of wastegate

Charge side of waste gate

What are these to?

Why is this bottom fitting open/not capped?



Will have timing and comp ratio's posted this afternoon.
I'm on a very limited budget (post D) So any help on $ saving/generic ways of doing thing would be appreciated.
Thanks so much for all the help thus far, I'm begining to be hopeful this can be worked out!
Sam
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'77 Ice Green 911s Targa that's almost a 930

Last edited by parasailsam; 01-25-2009 at 09:26 AM..
Old 01-25-2009, 09:21 AM
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One of them goes here and the other goes to the Auxiliary Air Valve which your engine does not have. I wouldn't try to hook them up, since your mechanic has chosen not to use these features.

In the picture above, the air metering plate has a switch which activates when the engine starts drawing vacuum. The switch then allows the fuel pumps to turn on. It looks like your fuel pump is pumping fuel as soon as the ignition is turned on.
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Old 01-25-2009, 09:31 AM
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Pumping fuel as soon as Ignition is on.

Is that OK?
It is commonplace in many cars/boats today, but don't know about the turbo set up.
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'77 Ice Green 911s Targa that's almost a 930
Old 01-25-2009, 09:39 AM
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I asked the mechanic to dissconnect the AAV and the CSV ov Rlyl8s suggestion, cause the thing idled way high and higher after warm-up.
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'77 Ice Green 911s Targa that's almost a 930
Old 01-25-2009, 09:40 AM
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I'm leaning towards a boost sensor switch, if it has one, or the boost recirculating hardware. Do any of you know if they 3.0 turbo's had recirculating valve?

I still do not like the way the wastegate is plumbed. If you're concerned about dirty air getting into the atmospheric side (vent) of the wastegate, I would run the hose to an area between the air filter and metering plate. On the charged side of the wastegate, I would run the hose to an area between the compressor output and throttle body.
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Old 01-25-2009, 09:41 AM
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Can't find any single wires that might be an overboost sensor...
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Old 01-25-2009, 09:57 AM
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Quote:
Originally Posted by parasailsam View Post
Can't find any single wires that might be an overboost sensor...
It's location is pointed out in the Porsche Parts CDROM....item 24 (top center).

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'85 930 Factory Special Wishes Flachbau
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Old 01-25-2009, 10:41 AM
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Dave,
If you look at post 29, 3rd pic down, you can see a bolt plugging the overboost sensor port.
So no overboost sensor, strike that one off the list.
Couldn't get the timing and comp done today, but will post tomorrow.
Thanks again everone.
Sam
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Old 01-25-2009, 02:45 PM
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Quote:
Originally Posted by parasailsam View Post
Is that OK?
It is commonplace in many cars/boats today, but don't know about the turbo set up.
It won't cause your problem. It won't be an issue until you're trapped in a wreck with fuel being pumped into the fire @ 3 liters per minute/80+ PSI.

Hmm. An '83 SC has way too much compression to run stock boost levels without an intercooler. It might have too much compression even with an intercooler, hybrid turbo (cooler charge air) and twin plugs.

You are aware the 930/50 series motor that system came from ran 6.5:1 from the factory, right?

Look at this and it might be clear why:

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Old 01-25-2009, 03:57 PM
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One other thing you want to check is the recirculation valve mechanism and hoses. The recirc valve is designed to open and recirculate the charged air back into the intake of the turbocharger. For instance, when you're accelerating and shifting, momentarily closing the throttle body. Now if this valve opens prematurely while your are accelerating hard under boost, charged air into the intake will be lost, circulated back into the area between the turbocharger inlet and metering plate and quite possibly causing the metering plate to close because there is no air being drawn from the metering area. Closure of metering, loss of fuel delivery...... Just a hypothesis ($0.02)
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'85 930 Factory Special Wishes Flachbau
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Old 01-25-2009, 04:15 PM
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Dave and Spuggy,
Thanks for the info...
Spuggy,
If that is the case ( to high comp) what to do?

Dave,
Could you provide schematics as you did before to help me locate the recirc valve/system?
I should be posting timing and comp tomorrow.
Any other questions I should ask the install machanic on Monday?
Thanks again guys, hope you all had a great wekend, and if you're ever in the Branson area, Kegerator beer is on me ;-)
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'77 Ice Green 911s Targa that's almost a 930
Old 01-25-2009, 05:00 PM
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The recirculation valve components are outlined in the diagram below. Note where the hoses go from this assembly.


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'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 01-25-2009, 05:24 PM
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