Sorry but not again.

911st:

Yes, it's me again. Why not consider a system that gives you power, efficiency, and safety all at once?

RC says the best way to do this is on the dyno. Engines blow up on the dyno all the time. How many dyno operators even listen to a knock sensor?

If you tune by listening for knock, you are tuning to keep the worst cylinder quiet.

I just ran across a couple old threads with some supporting comments from "350HP930". I don't know this guy from Adam but he loved the system. He hasn't posted in quite a while so I don't know how to get a hold of him:

http://forums.pelicanparts.com/porsche-911-technical-forum/117549-930-how-can-i-richen-up-fuel.html

http://forums.pelicanparts.com/porsche-911-technical-forum/120086-anti-detonation-system.html

The unit he had was our first generation, produced from 1991 to late '98. Unlike his early unit, the current version incorporates boost retard with both start and rate controls.

John's system rocks. Nothing comes close in the same size package.
The application I've used it on mainly is known to be the most knock sensitive internal combustion engine and it's saved me dozen's of times.
Tuning on the dyno gives you a base line to test and setup. Actual real world conditions is where the car is driven/race at. Knock detection is needed when finding the limits during those conditions.

Sorry for implying dynos are for blowing things up. That was a bit of a non sequitor. :)

I was trying to say that even a tune developed on a dyno can be improved upon with an individual cylinder knock controller.

MoTeC, Autronic, and Link have recently added individual cylinder knock control. Why would they go to that expense if the tuner already has full control over fuel and timing maps?

Imagine how much more useful the unit is on an engine that relies on thirty year old mechanical systems to control fuel and spark.

crispeed: Thanks very much for your support.

While not a 911, my 951 is equipped with one of John's Safeguard boxes and I sell his box bundled with my Vi-PEC EFI kit. The closed loop, individual cylinder knock control can't be beat. I have developed my ignition map logging the J&S activity to where when detonation occurs, my logs indicate the amount of timing retard the box applied to eliminate the knock. With all variables factored into the knock event - MAP, range of RPM, AFR, I have refined my timing map to within a few tenths of a degree of the "edge" of detonation. I leave no power on the table and I safety extract the most from my engine. I have no need for building a "safety buffer" into my timing map because the J&S makes individual cylinder corrections in real time without me even feeling it. Beautiful thing is that it still lets me know about it thru my logs!

Here is a screen shot of my J&S box in action. As an additional safety buffer, I have instructed my ECU to pull boost if the J&S is pulling more than 2 degrees of correction. The box will allow up to 10 degrees of correction without you even noticing it is doing anything. Boost is the black line and the purple line is knock actvity.

http://forums.pelicanparts.com/uploa...1272576649.jpg

For any of the non believers that are under the impression that the J&S or any other knock controller do not have the ability to distinguish between engine noise and knock, the great thing about the J&S is that you can use earphones to verify any signs of knock.

The human ear is far superior to any knock specific electronic device, so all I had to do to accurately set the sensitivity adjustment on the J&S was to listen for the sound of slight knock (readily audible) and coordinate that to the triggering of the activity LED(s). Once the timing between the audible knock sound matches the activity LED(s), the box is set to its job!

Eventually, we plan on offering Vi-PEC EFI kits for the 911 line without a doubt using the J&S as a key component.

Thank you John for an AMAZING product.

John,

I appreciate John's ingenuity and perseverance and I'm quite sure you have a fine product but I wish you would just start a thread of your own. It's getting to the point that if we had a forest fire thread here and the word "spark" was in it I would be reading about John's knock sensor all over again.

Cole

Ouch, the door hit me in the butt on my way out.

+1 or is that +2?

John,

Tact and sutulty have never been my strong suite.

I promise if ayone asks about knock sensing I'll personally give them your name.

Thanks !!!

Cole

I apologize if I have offended anyone here - I mistakenly only read the first page of this thread and thought my input may be useful. OP, let me know if I should just delete it.

Not a problem.

If you dig back in this thread I think you will find this disscussion, 944T v 911, motor noise interferance, the effort required to adapt a 911 to knock sensing -- was covered.

Vic,

By all means if you have something to offer in reference to a post, that's what we are here for. I apologize for sweeping you up in this, not your fault and including you was wrong and totally my mistake. And believe it or not I don't dislike John, as a matter of fact I'm very impressed with him. I just want to go look at his site, which I have done, instead of getting constant commercial endorsements from him.

I think John has a wealth of information to contribute to many threads that don't pertain to knock sensors but I don't see that. I see him siezing every opportunitie to plug his product instead of contributing to a thread and that was not, and is not what these forums are about.

Wayne could go the cable networks route and flash Paid Programing in the middle of a thread and sell advertising.

Cole

I am wondering if we can adapt a late SC dist pot to a turbo?

It seems it has both the ability to advance with vacunm and as it has vac retard so it should let it retard with boost using only one conection. The stock dual pot dist only can retard.

I am told Vac retard is about 7-10 deg (this would function as boost retard) and vac-advance about 5-8 deg (do not want this active at idle). That makes for about a 15 deg swing from light load at cruse to full boost WOT.

I am thinking this might let timing would look about like the following:

-12 deg static timing (no vac retard and cooler more efficent idle)

15 deg of mechanical advance (same as stock)

-27 being the total deg of static plus mechanical. (WOT no boost at speed)

On boost retard would bring it back to about -19.

At cruse, vac advance would take timing to about -34.


Then fine tune from there. The major gain is access to better efficency and a cooler running car at cruse.

I am not sure we will be able to acces Vac Retard at idle though it might be possable.

Probable Correction!!!

Euro Dist has Vacuum Advance, not Retard.

During this thread info was presented that the single connection euro dist only has vac retard. It seems that is not the case.

It seems to have Vacuum Advance with makes more sense.

Looking at a picture of the euro dist bellow, it looks like the dist turns counter clockwise and the pot pulls, advancing timing at cruse.

There is not effect at idle as it is attached to a ported connection that does noe see vac at idle.


If this is true as I suspect then idle speed should not be effected if the connection is removed at tile. If it is a Vac Retard, disconnecting the vac line would increase idle speed.

I like that if there is a rupture on a single euro that it should fail at a save timing value for on boost. The dual pot with a failure might not retard on boost which could cost a motor.

On the other hand, I suspect a dist with boost retard will have a little better retard curve over a vac advance dist which will probably loose all its advance with loss of vac before boost is achieved.

Just a thought.

http://forums.pelicanparts.com/uploa...1254023296.jpg

I'm not sure that I understand. Are you drawing a distinction between a single pot single hose and a single pot twin hose Euro? The extract of the Porsche manual says clearly that there is vacuum retard at idle and also retard on boost which is exactly as I have found in practice on my 1984 Euro with a single pot (twin hose).

David

David,

Sorry, all have one pressure box or pot.

The early 3.3 euro turbos, as pictured above, seemed to have a single vac line conection for vac advance.

The later 930's, like you seem to have, seem to have the US style dist with two vac line conections. This style only has retard. Vac retard at idle and then retard on boost.

sub

Had a little time on my hands today and wished to refresh my memory on timing, such as it is. Old rehash; but here's my attempt to put 513 posts into words. Do I have it all correct....I doubt it, but you decide.

Good Lord, 99% of this thread is supposition and creative thinking (better referred to as "learning"), whereas the remaining 1% may actually hit on some truths. If I were to attempt to distill it all down to what's happening with timing control for a dual-pot distributor, I would start by reading posts 74 and 138:

__________________________________________________ __________________

...tested both sides of the vacuum pot under pressure and vacuum. I found that the advance side of the dizzy responds quite a bit to vacuum and retards a little under pressure. The retard side only responds to vacuum. So at idle the timing is retarded by vacuum, when you push the pedal that vacuum is gone advancing the timing. when you accelerate the advance side sees vacuum and advances the timing with both vacuum advance and mechanical advance. when under boost the vacuum turns to pressure in the line, eliminating the vacuum advance and starts to retard the dizzy with pressure. Am I understanding this correctly? 911st mentioned a solenoid plumbed into the advance side, this is confusing to me. Which solenoid are we talking about. is it the one that looks identical to the one on the retard side, that is closed for about a minute to give you a high idle at startup? I thought the other one was used only for emmisions air pump etc. or are we talking about the thermal valve up by the crankcase breather hose.
__________________________________________________ __________________

...put around 15" of vacuum into the left side or outer advance pot that the red line goes to the engine speeded up.
When I did the same to the inner or right side retard pot the blue hose goes to, the engine slowed down..
That means the left one is advancing the timing when vacuum hits it and the right side one is retarding the timing when vacuum hits it and my guess is they cancel each other out when boost pressure replaces vacuum in the 2 lines leaving only centrifical advance which may be what boost retard amounts to.....

__________________________________________________ __________________


The truths: Vacuum at the retard side of the can (closest to the distributor) AT IDLE will cause retarded ignition. Open the throttle a little and that vacuum goes away - because of where the port is located in the TB - causing the ignition to immediately advance back to static timing....or where it would have been had it not been retarded due to the vacuum. Now push open the throttle plate a bit more and two things happen: You gain some amount of vacuum advance through the advance side of the can - because of where it's port is located in the TB....and also gain mechanical advance as the rpms increase.
Now put your foot further into the throttle and you transition from vacuum to boost; i.e., your vacuum (and thus your advance) goes away and all you've got left is the mechanical advance portion. Net-net, your timing just got retarded when the vacuum advance went away. Under boost, both sides of the can see "pretty much" equal pressure and negate each other but you still end up with the same result....the absence of vacuum advance and nothing but mechanical advance left. That alone drops your timing probably 10 degrees to protect during boost.

As for the two solenoids repeatedly in question (one electrical and one mechanical thermo time) the mechanical one hidden behind the fuel distributor blocks the vacuum advance when cold, and the electrical one blocks the vacuum retard when cold...but nobody seems to know how it gets it's signal to open or close. Quite frankly, neither of those two gizmos are needed and just serve to heat up the exhaust gas for emissions purposes.

Can someone enlighten me on the thermoswitch?

It's in line with the boost signal to the distributor that causes boost retard under boost...

I understand the same line does vacuum advance once warm...

I see a lot of folks remove this switch... Any consequence to doing that? Higher advance under idle when cold? Does it making starting difficult?

When cold, air doesn't blow through this valve... Either boost or vacuum. Does this mean you don't have boost retard until a motor is fully warmed up?

Did most of you take this out of the loop? If this switch fails, doesn't that mean your motor grenades as you then lose boost retard?

THIS IS FOR 1986 TO 1989 US 930'S ONLY!

The Thermoswitch cuts off vacuum to the outside connection on the distributor when the engine is cold, raising the engine idle speed, which is nice for charging, warm-up, and general drivability.

The presence of vacuum retards the ignition timing. The absence of vacuum allows it to be advanced.

The other distributor vacuum port, on the inside, is responsible for boost retard.