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Acceleration Junkie
 
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Quote:
Originally Posted by timc View Post
Chris, Are you saying to set his timing at 36 deg at 4k instead of 26?? Can he safely do that with a stock engine without getting detonation?
Yes, set timing at 36 instead of 26.
It's not necessarily safe. That's why I recommended Alan flog it up to boost. No danger to the engine there.
I run my ’79-930 engine with 38-deg/4000 on the street, pull timing out to 29-deg at 1-bar with a stock distributor 5-deg retard supplemented by a boost controlled retard. At stock timing, my engine is helpless when not in boost. With 12-deg extra timing at low rpm, engine behaves well.
I believe RarlyL8 Brian has it right. The early 930's are simply dogs when not in boost. What does the turbocharger add? 100-HP? Pull 100Hp out of a normally aspirated engine with 7:1 compression and see how it performs under 3k-rpm.
Old 06-19-2008, 08:55 AM
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Not a bad thought Brian. I was about to say there is no one in the region (we are quite remote) that I know has any experience of a 930. Then I just remembered there is a guy with a late model one. I tried to buy his SC once - but he had just sold it. Kept the 930, and regretted it - found it too hard to drive. Saw the car a few weeks ago. (Maybe he'll let me take his for a 'spin')
Alan
Old 06-19-2008, 12:02 PM
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I may have solved the problem. I am trying to get hold of this local 930 with no luck so far.
But I took mine for a quiet drive down the road in the pre boost zone and light throttle and watched the AFR (that gear is worth its weight in gold). It sat around 14 and then always leaned off for a considerable period under light throttle. I concluded maybe the fuel piston was not able to respond quick enough to the throttle plate movement - lagging too far behind. I set all my fuel pressures by the book when I went thru it - because they were all well out of range at the high end (120 psi system etc). So I have dropped my warm WUR pressure by 10 psi (not boost pressure). The AFrs seem better and the car definitely feels better. They take a short hike towards lean and come on with fuel much quicker (the lag time in fuelling up is shorter). Hard to know on your own on a road - so will try out on track again at first opportunity - but I am sure it has improved.
I will still try and get the local 930 for a comparative run.
Alan
Old 06-19-2008, 09:27 PM
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See if this can help you. It's from a 3.0 but you get the picture.
Also, a programmable ignition could help you. Then you could tweek advance curves to help you get out of the hole.

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Old 06-20-2008, 02:36 AM
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Alan, it is unlikely that if you find a stock 930 to drive that it will also be in a perfect state of "tweekedness" or tune. CIS has a lot of room within the tolerances were it will run acceptable but is far from optimal.
Every little bit of tweeking you do will be significant in the response you feel from the engine.

Goran, can you interpret that graph? I read those so infrequently that I have never gained a full understanding of how those islands affect operation and specific engine characteristics.
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Old 06-20-2008, 04:07 AM
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Quote:
Originally Posted by Alan L View Post
.......... mine seems fairly dead until it picks up to around 0.1 bar, then it lights up and is very throttle responsive.
Standard turbo, 0.8 boost.
Alan
.1bar? Sounds fairly normal for 930 w/3LDZ Turbo and stock cams. I would check the distributor advance making sure it's working ok.
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Old 06-20-2008, 04:08 AM
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The distributor advance seems OK - I did look at it - but have not mapped it completely.
Am interested in the possibility of pre boost advance - if experience tells us it works.
Normally, in general principle - which I have applied to my previous NA race car, you run your distributor curve slightly behind the engine performance curve, eg if the high performance narrow band (big overlap) cam comes in at 4000, you don't want full advance until just after 4000. It gets up onto the cam quicker this way.
Brian, I agree that small tweeks in the right direction seem to have significant effect. I am surprised how much the engine characteristic changed. I can see and feel power from 2000 rpm - but 'sadly' it has knocked some of the vicious edge of the turbo effect at 3000 (all or nothing - on the edge of 3000). Simply because it is already pulling its weight prior to 3000 - I might miss that serious kick in the pants - but it does feel better overall. You would think I have changed the turbo for a K27.
I am considering dropping another 5 psi, it made such a difference. Like Gorans map - I also see pressure building quicker - at 2000 - not into boost - but it seems to have moved out of deep vacuum much earlier. Don't know why, or if it is my imagination - but I like what I see.
These cars are amazing. I constantly have to tell myself this is a bog standard 25 yr old 'road' car. It is a race car that spends time on the road, and a rocket ship on wheels.
Amazing.
Regards
Alan
Old 06-20-2008, 12:24 PM
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Quote:
Originally Posted by RarlyL8 View Post
The stock 930 has a power band of about 2000rpm, from 3500rpm-5500rpm. That's really not an exaggeration. Is this what you are seeing? I believe that short power band is one reason behind the long gears of the 4 speed. That combination makes for a miserable auto-x or short track experience.
And exactly why I'm building my second 3.6......
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Old 06-20-2008, 04:23 PM
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Quote:
Originally Posted by timc View Post
Chris, Are you saying to set his timing at 36 deg at 4k instead of 26?? Can he safely do that with a stock engine without getting detonation?
Just to clarify what Chris said. He is saying to alter your timing, BUT only for testing purposes and not let any boost build up at all. It is purely a test to prove if this is infact the problem or not. Do NOT get in to boost.

Quote:
Originally Posted by 356-930 View Post
If you're running factory timing - (27-29 deg full) - add another 10-deg and you should see significant improvement in low rpm performance. If you're nervous about too much timing under boost (good thing to be nervous about) MSD's multi function ignition control system can readily and reliably pull the extra timing out.
Do you have a link to that device?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg

Last edited by NathanUK; 07-05-2008 at 02:54 AM..
Old 06-21-2008, 08:13 AM
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Quote:
Originally Posted by NathanUK View Post
Do you have a link to that device?
Here's a link to MSD's Multi Function Ignition Controller, P/N 8979.
http://www.msdignition.com/htmlhelp/8979.html
This device is sophisticated enough to control timing of individual cylinders (within limits of course).
Old 06-21-2008, 01:14 PM
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I think you have the 8977?

How do you have yours triggered? Are you using a 930 dizzy with a 6AL?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 06-21-2008, 01:49 PM
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Quote:
Originally Posted by NathanUK View Post
I think you have the 8977?
How do you have yours triggered? Are you using a 930 dizzy with a 6AL?
With 20/20 hindsight I wish I had purchased the 8977. (Part of the 930-experience learning curve.) I am running a stock 930 distributor that pulls 5-deg of timing out by 8-psi. Ignition is an MSD 6AL with an added MSD 8762 Boost Retard module.
I believe the MSD 8977 is a better system choice as it has more flexibility, features and adjustablity than the simple 8762 boost retard module.
Old 06-21-2008, 11:59 PM
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I dunno how your dizzy advance/retard is configured (there are plethora of combinations depending on which market car was sold for, Cali and Japan being the most complicated) but you could re-route retard to give you more advance prior to boost?

I did just that on my SAAB og900 daily driver...I connected retard line on plenum itself instead of pipe going off the throttle housing (which gives no vaccum on idle). That gave me much more poke off boost. I'm running on E85 though so knock is more or less impossible.
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Old 06-22-2008, 01:29 AM
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The 8762 looks quite VFM except that if the knob got moved by accident...

I agree, the 8977 would seem to be the way to go.
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 06-22-2008, 04:41 AM
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Quote:
Originally Posted by beepbeep View Post
I dunno how your dizzy advance/retard is configured (there are plethora of combinations depending on which market car was sold for, Cali and Japan being the most complicated) but you could re-route retard to give you more advance prior to boost?

I did just that on my SAAB og900 daily driver...I connected retard line on plenum itself instead of pipe going off the throttle housing (which gives no vaccum on idle). That gave me much more poke off boost. I'm running on E85 though so knock is more or less impossible.
My stock 930 dizzy is a dumb 2-port device. Vacuum on both ports retards timing (because vacuum on the boost retard port has no effect). Positive pressure on both ports also retards timing (because positive pressure on the "vacuum advance" port has no effect). Confusing huh? In the case of a dizzy, dumb is a good thing.
I used to run the engine 22-deg BTDC, no vacuum advance (same effect as plumbing retard line on plenum) and still not enough timing to wake the engine up below boost. It liked 27-deg BTDC at idle but it wouldn’t really idle, misfired above 2000 rpm unless under load and EGT got too high.
To optimize these early 930’s performance, a crank fired ignition and computer controlled timing has my vote. And, if I get to vote twice, add EFI. (This said, IMO, an early 930 is a wonderful power plant including all it's limitations.)
Lastly, I apologize for being so far off the topic.
Old 06-22-2008, 10:39 AM
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Quote:
Originally Posted by beepbeep View Post
I dunno how your dizzy advance/retard is configured (there are plethora of combinations depending on which market car was sold for, Cali and Japan being the most complicated) but you could re-route retard to give you more advance prior to boost?

I did just that on my SAAB og900 daily driver...I connected retard line on plenum itself instead of pipe going off the throttle housing (which gives no vaccum on idle). That gave me much more poke off boost. I'm running on E85 though so knock is more or less impossible.
Goran, Just to add to 356-930 post, my dizzy is a single port. From previous discussion I think the conclusion was it probably belongs to an earlier engine, and has a more aggresive curve. It hooks into the throttle body - but without removing intercooler etc, I can't tell which side of the butterfly it is plumbed into.
If it was the lower side - this would have a different effect than the topside?
I suspect it is the lower side - in which case I have the effect you are describing?
356 -930 - I'm not sure this is off topic - if it all relates to pre boost power - which was my original query. Given I have now found some fuel related power from 2000 rpm, I'm interested in what else I can find down in that range.
Alan
Old 06-22-2008, 12:24 PM
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Alan, if you find a way to retard timing when on boost rather than it being retarded because there is no vacuum to advance the timing please let us know.
I'm sure the MSD stuff will work but I quickly added up the cost in my head
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 06-22-2008, 01:19 PM
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Quote:
Originally Posted by Alan L View Post
, . . .my dizzy is a single port. . . . .
Alan
If it's a single port, it's vacuum advance and gets its air signal from below the throttle body. In application, at idle/high vacuum, the timing is "fully" retarded. Whenever the throttle body is opened and the more it's opened, the manifold vacuum decreases which advances timing.
Since your dizzy has no boost retard, it may have both low vacuum and centrifugal advance capacity (to limit advance at full boost).
You can check vacuum advance capacity at idle with a mini-vac and of course centrifugal/full advance at 3500-4000.
Your engine may truly benefit by use of the MSD 6AL and 8977 controller.
Sadly, as Nathan notes, improving performance via the MSD route is expensive but then what isn't expensive when it comes to a 930 and pushing the performance envelope?
Or, find a dual port dizzy which will buy you 8-11 deg of boost retard so you can get more aggressive timing when below boost threshold.
It may be beneficial to call Henry Schmidt, Supertec Performance, 760-782-3062 (San Diego, CA area) and inquire about a distributor that might accomplish the desired - he knows about these things.
Chris
Old 06-22-2008, 01:44 PM
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[QUOTE=NathanUK;4017485]Alan, if you find a way to retard timing when on boost rather than it being retarded because there is no vacuum to advance the timing please let us know.
QUOTE]


You would not have thought it that difficult really, would you ? have the plate move one way on vac, and the opposite on boost. More vac, more adv, more boost, more retard.
How hard can it be? If you plumbed it off similar port to clock boost gauge, how far wrong can you go?
Alan
Old 06-22-2008, 04:08 PM
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I am considering giving up my day job, and just getting the 930 going real good.
Seems like a full time occupation to me. Just that work keeps getting in the way.
Alan
Old 06-22-2008, 04:16 PM
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