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Question Thought on this AFR graph?

Alright boys!
I took the 930 to a friends place (not a Porsche tech) to make sure that I was not going to grenade the motor on the CA fuel, and this is what we have:
Timing 26* BTDC at 4000 RPM









What do you AFR tuning genius's make of all this? The car feels like it is choking from 2-4k RPM, (shuddering and unhappy).
The turbo starts spooling at about 2800-3000, but nothing really happens until roughly 4200 RPM. Is this due to The AFR being in the 10-11:1 range?
How do I get it closer to 12:1 while bringing the AFR's above 5000 RPM down to the approximately the same range?
I do have the Andial enrichment system installed (don't flame me Craig! The thing came with the car!! ), but the PO did not have the instructions and was no help in letting me know how system worked. It is currently on the counter-clockwise most setting, with five possible other indexed settings.
With my current configuration, am I a good candidate for the adjustable WUR? Or is it over kill for my motor?
Realistically I will only be at the track 3-4 times a year, and other than that the duration of time on boost will be, unfortunately, limited...

Basically: HELP!!! I'm Lost!
-Sean
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Sean D. 1987 930
India Red/Beige/Black; Mahle 3.4L; Kokeln IC; K27 7200; GHL Headers; Borla Stainless Muffler; SC cams; Sachs Aluminum Clutch; Aluminum flywheel; Bilstein Sport Shocks; Adjustable Rear Sway Bar; Weltmeister Shock Tower Brace; Lowered and Corner Balanced; MOMO RSGT Seats...
Old 03-29-2008, 11:25 PM
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Not sure about the andial enrichment set up so cant comment although it looks like you are getting a mass of fuel in there far to early in my opinion,with an adjustable wur and with some tweeking you could iron that out one hell of a lot better and wouldnt need the andial.
if you were still getting too much fuel too early you could also delay the fuel enrichment more with the rpm solenoid!
Old 03-30-2008, 03:32 AM
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***** can the Andial ;-) Look how rich it is on the bottom end and lack of fuel up top.......

Adjustable WUR --- and the RPM switch is definitely needed here (will delay that full boost enrichment until 4500 or so and gain HP and use less fuel, etc etc)
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- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 03-30-2008, 07:58 AM
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Am I reading correctly that this engine sees 1.35bar @4000rpm with a 12.9:1 AFR?

What is your engine setup?

Obviously this is a problem. That huge black cloud behind you at 2500rpm is killing power, mileage, and washing your cyliders. So yes, you need to make your WUR adjustable and fix all of the parameters - cruise, threshold, and boost.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 03-30-2008, 10:35 AM
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- and manage that massive full boost enrichment that can't be tuned out via the adj WUR - an RPM switch is a must in your case.
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"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 03-30-2008, 12:14 PM
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Not necessarily. It takes more tuning time but full adjustment is possible without the rpm switch.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 03-30-2008, 01:28 PM
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Could be possible, but from others' experiences it may not be likely.

On a 930 with CIS - absolute full, massive 100% fuel dump occurs at full boost and the way to manage this is with the ~delay~ of full boost enrichment via the RPM switch.
Several people over on Rennlist have found this to be absolutely true.

This is especially the case if he finds out if he requires additional fuel via the IA fuel head.
(Which he probably will not need)

A modern turbocharger produces full boost at a much lower point than the 1970s era turbochargers did and all that extra fuel is tough to manage with the WUR alone - and this is why Brain Leask has the RPM switch and solenoid. It sure works well!
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- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 03-30-2008, 01:53 PM
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A few of those readings remind me of my blood pressure when I rev my baby up and then my wife comes out into the garage and yells at me to shut that *****ing thing off... have a nice day boyz!!!
Old 03-30-2008, 02:07 PM
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My guess is that the rpm switch was incorporated as a shortcut to the detailed tuning required to get it right. Most folks don't have the patients for it. You still have the same amount of tuning if you want the entire range perfect.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 03-30-2008, 05:03 PM
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Shortcut. Uh...no.
Hang tight, I'll post some information.
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"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 03-30-2008, 05:12 PM
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Your course of action should be this:

1) Adjustable WUR from Brian Leask.
Tell him what you have and he will send it roughly pre-adjusted.

2) Check AFRs.

3) Adjust WUR. It does indeed take patience, but the instructions are phenomenally superb so it is actually ......fun

4) Check AFRs again. Possibly invest in an AFR (Innovate brand is good) setup.

You have so much fuel right before probably full boost (when is full boost on your car?) that this HAS to be adjusted using the WUR.
Post full boost (prob 3k and above) to probably 4,400 (very typical RPM switch activation point, by the way)

I would surmise that this would benefit from the RPM switch *BUT check and perform steps 1-3 first*.

See below for operation and theory:



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- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 03-30-2008, 05:40 PM
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Yes, it is a shortcut. A bandaid if you will.
By adding the RPM switch you alleviate (note I did not say eliminate) the need to go inside the WUR and mechanically adjust the threshold.
As I said before, most folks don't want to do that, and that's fine. For product dispersion to the masses that is a GREAT idea which allows adequate external adjustments. BL has a great product and I send folks his way almost daily.

Now back to the topic at hand.
What is the boost level? Is it really 1.35bar? How was this engine built?
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 03-30-2008, 08:39 PM
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Craig: you know I love you Andial hatred!!!
Thank you for the reading! I am very much considering the BL WUR.

RarlyL8: Yeah, no **** on the boost levels...
As far as the engine build goes;

3.4L Mahle P&C 7.0-7.5:1 CR (the shop could not remember which compression ratio)
SC cams
Stock bottom end
K27 7200 Turbo
Kokeln IC
Stock waste-gate (1bar spring)

It is throwing me for a loop, my best guess is that I am experiencing higher boost levels than the WG spring is set for because of the GHL headers? Much like the Tail WG's are experiencing with the same headers???
356-930, and I have also been corresponding and he brought up a good point and question: shouldn't the boost peak just above the WG spring pressure, and then hold steady at that WG's spring rate, instead of tapering off, as shown in my boost chart?

I really appreciate the time fellows!
-Sean
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India Red/Beige/Black; Mahle 3.4L; Kokeln IC; K27 7200; GHL Headers; Borla Stainless Muffler; SC cams; Sachs Aluminum Clutch; Aluminum flywheel; Bilstein Sport Shocks; Adjustable Rear Sway Bar; Weltmeister Shock Tower Brace; Lowered and Corner Balanced; MOMO RSGT Seats...
Old 03-30-2008, 09:30 PM
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Both a K27 7200, or a K27 7006's boost will taper off as revs go up just like your graph shows. They just run out of breath.

If you install a K27 HFS then it will hold max boost all the way to redline, even in 3rd gear... and you should be a little richer up top, like around 12:1 or even 11.5:1 if you go that route.
Or it may detonate and break rings, burn pistons, and all that fun stuff.

I would recomend Brian's RPM switch and solenoid and adjustable WUR too...
The 930 WUR gives enrichment when it sees boost no matter what rpms the engine is turning, so you delay the boost pressure from getting to it until around 4500 rpm with the rpm switch and air solenoid.
Old 03-30-2008, 09:56 PM
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Quote:
Originally Posted by Quicksilver77 View Post
Craig: you know I love you Andial hatred!!!
Thank you for the reading! I am very much considering the BL WUR.

RarlyL8: Yeah, no **** on the boost levels...
As far as the engine build goes;

3.4L Mahle P&C 7.0-7.5:1 CR (the shop could not remember which compression ratio)
SC cams
Stock bottom end
K27 7200 Turbo
Kokeln IC
Stock waste-gate (1bar spring)

It is throwing me for a loop, my best guess is that I am experiencing higher boost levels than the WG spring is set for because of the GHL headers? Much like the Tail WG's are experiencing with the same headers???
356-930, and I have also been corresponding and he brought up a good point and question: shouldn't the boost peak just above the WG spring pressure, and then hold steady at that WG's spring rate, instead of tapering off, as shown in my boost chart?

I really appreciate the time fellows!
-Sean
Sean, you are right to show concern regarding the boost level because the W/G should control what you set. First check your W/G for proper function. Much of the A/F ratio problem is your uncontrolled manifold pressure and excess air.
After checking your W/G have you relocated the W/G pressure tap from it's stock location? Assuming the W/G is functioning properly, when I see a boost curve like yours it has been modified by electrics (modern) or relocation (old school) of the pressure tap controlling the W/G.
Next, but of lesser importance, your comment about the GHL headers may be contributing to the boost curve shape as their 90 degree branch off pipe from the base of the turbine inlet is widely known to be less than ideal for proper exhaust flow to a W/G. Basically, you are dealing with turbulant flow because of this improper design and stange things happen in turbulant flows.
Once you have control of the manifold pressure a slight boost overshoot is generally considered desirable for "response"....but not at 1.35bar.
Old 03-31-2008, 07:31 AM
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Header design does affect waste gate action.
You can get a boost controller or swap in a 0.8bar unit and see where it ends up.
The K27-7200 does peter out on top but given your boost and AFR issues that is not a bad thing.
I also suggest an adjustable WUR. BL has a good product and can help you set it up.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 03-31-2008, 07:35 AM
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Quote:
Originally Posted by RarlyL8 View Post
Header design does affect waste gate action.
You can get a boost controller or swap in a 0.8bar unit and see where it ends up.
The K27-7200 does peter out on top but given your boost and AFR issues that is not a bad thing.
I also suggest an adjustable WUR. BL has a good product and can help you set it up.
We are in complete agreement and IMO there are several component issues.
Header configuration delivers power to the compressor through driving the turbine. Better configurations deliver more power sooner, but this power should be controlled by the W/G alone, especially at less than maximum flow conditions. Power often drops based on the turbo's size and efficiency but the boost level should remain as set.
Being a less than perfect world the boost curve will have a different signature with component changes. As I said, if the GHL headers have a signature of a slight onset boost bump this is desirable assuming it's within reason.
Yes, he needs to work with A/F control, and probably needs the WUR upgrades based on the collective experience on this site but I think we will agree he doesn't want it fixed at 1.35 Bar boost. Is it typical to use a .8bar spring to control boost at 1bar?

Last edited by copbait73; 03-31-2008 at 02:05 PM..
Old 03-31-2008, 08:10 AM
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The 0.8 bar spring is a bandaid to get around the header design flaw. If 1.0 bar boosts 1.35 bar then 0.8 bar might be good for 1.08 bar given the 35% overboost is linear. Not an ideal situation but it should save the engine if modding the headers is not an option.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 03-31-2008, 10:13 AM
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Leaving out the RPM switch when required is a questionable idea and makes tuning the thing so much harder.
But if you like that stuff...

Brian, you ought tell us exactly HOW this is done with extreme richness at the low end.
After all, this is virtually central to 77's problem.
~

That engine is extremely / unecessarily 'peaky'. THe HP curve ought to be much flatter -
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- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 03-31-2008, 10:17 AM
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Wow 1.35 bar! OK I am fairly new to the 930. but it seems to me that you definately need to get that boost down. When I installed my GSF headers I was around where you were with a 1 bar spring. I found that I needed to go down to .7 to get my desired .9 bar. As stated above it is probably a real good thing that the turbo is running out of breath. Once you get the fueling sorted out and possibly a more efficient turbo. that motor is going to be hurting at 1.35bar and have much bigger problems. yikes! Just my .02

Eric
87 930
Old 03-31-2008, 11:44 AM
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