Sloth

Danno,
What are you expecting the kit to run for? <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

PrerYDoG

What is the hard limit on the 18PSI amd 320 - 325 rwhp? Is it a 3bar MAP sensor, which I would think would allow up to, roughly, 28PSI boost?

Also, then, I take it that the chips are useful in that they allow for more boost and a raised RPM (their fuel mapping won't matter anymore correct?), but won't having chips negatively effect as they dial-in ignition retard? Will not running w/o chips be benefitial in not having ignition retard?

PrerYDoG

Houston - I'm going to execute a vertical bump, be advised, executing a vertical bump.

Space Shuttle Out

Danno

Sorry for the delay Mark. At the very lowest functional level, you still have the stock Bosch DME/KLR boxes controlling the engine. And the ignition and fuel values are pre-programmed into the chips. There is no way to not use chips because at a minimum, you'll still need the stock chips that came on the car.

The AFM-Link MAP-sensor upgrade allows you a simple way to remove all intake restrictions and increase flow similar to a MAF upgrade (initial testing shows that removing the stock AFM is worth 1.5psi of boost). And it's even more free-flowing than a MAF-6 upgrade because there's no sensors at all in the intake tract before the turbo. Also the instant programmability of the box allows you to overlay a fuel-correction map on top of the fuel-maps programmed into the DME chips. This is similar to the ARC2 unit, but has much higher resolution and finer adjustments.

Please refer to these threads for background info on MAP sensor upgrades:

<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic&f=15&t=004313" target="_blank">Topic: lets talk MAP sensors (kinda long)</a>
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic&f=15&t=006764" target="_blank">Topic: APEXi S-AFC?</a>
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=001466" target="_blank">Topic: MAP sensor upgrade 1 </a>
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=001694" target="_blank">Topic: LINK SYSTEM UPDATE 2 </a>

On the ignition side of things, for each boost and load level, there is but one optimal ignition timing for each power stroke of the engine. That's the timing that occurs right before the edge of knock/detonation to maximize combustion pressure (BMEP) in the chamber as the piston goes through TDC and starts to head down. These ignition maps are programmed into the DME chips. Because the flame-front propagation and combustion rate is fixed (about 23,000ft/sec?), yet piston speed changes with RPM, you need to ignite the mixture earlier and earlier as the RPMs go up to make sure all of the mixture is fully ignited by the time the piston passes TDC and starts to head down.

So, all of these factors are incorporated into the timing maps on the chips. However, due to variations and air-temperature, the engine's state of wear and tear, fuel-quality, user-installed upgrades, etc., the pre-programmed ignition map may be too agressive for the conditions and you'll get knock & detonation. This is where the knock sensor somes in. When the KLR hears knock from the engine, it tells the DME to dial back ignition 3-degrees. If the knocking continues, ignition will be turned back 6-degrees. Personally, I think this computer is limited since it really should be able to dial back ignition 10-15 degress if necesary. And it should be able to dial back ignition on a per-cylinder per-RPM basis. But these are ancient '80s computers and they were programmed with a fixed stock configuration in mind.

As a result, more ignition advance DOES NOT guarantee more power. Conversely, retarding the spark DOES NOT mean you'll lose power as well. In fact, if you are experiencing knock/detonation, retarding the spark to the point where the knock/detonation stops will yield you the same power (maybe even a little more), and save your engine too.

Now as for hard limits, there are several.

First is the flow-limits and efficiency of the stock turbo. In stock trim, both the K26/6 and K26/8 turbos drop boost in the higher RPM ranges to 10psi. Bumping max-boost up to 15psi will cause a faster drop-off as you go from 15psi at 4000rpm to 10psi by 6000rpm. You might be able to squeeze a little more out of them by using aftermarket boost-controllers and wastegates. However, you can't change the efficiencies of these turbo. They'll simply heat up the air too much at higher boost levels. I would surmize that with stock turbos, you can't run more than 15psi and get will about 270-300rwhp max.

The second hard limit is your fuel system. We haven't found any official specs from Bosch on the flow rates of the stock Turbo/TurboS injectors. Imperical testing shows that the same part# injectors flow different rates between two different sets of injectors from two different people. Even when tested by the same company R.C. Engineering. However, numerous people have reported actual-use experiences of these injectors maxing out at 100% duty-cycle around 280-310rwhp. Depending up the other upgrades in your car (free-flow intake, turbo, head work, exhaust, etc.) this limit can be reached at around 13-16psi of boost.

So really, the pressure limits of the MAP sensors are well beyond the current limits of the car. To make serious HP, you'll need a larger turbo, injectors and fuel pumps (Paxton, Aeromotive, etc.).

PrerYDoG

Danno - as always, the kind of reply I have come to love and expect from you , no need to reference older threads about engine management, I've read them ALL (been interested for awhile, waiting for the right one).

I like the free flowing - restrictionless idea, but how bout them chips? Will their timing retard still be in effect? Would it be better to run without them? We'll there fuel maps even be taken into consideration? If I can replace the KLR for the upped rev-limit and remove the over-boost restriction, great, and leave the DME as is so that the timing retard won't reduce power...

Also, I recognize that there is efficiency restrictions on the current turbo and ignition/fuel system. What I'd like is a new turbo, exhaust upgrade, injector upgrade, FPR, Wastegate, boost controller and a Link Sys system. At this point I want to know that the Link sys is NOT the limiting factor (for boost, ability to add to fuel, or whatever reason).

toddk911

So it will be set for the basic booost and upgrades, but will still be adaptable up to 18 psi, upgraded turbo etc?

Indica

Can we get a realistic ETA on the kit? THX

TT

[quote] These ignition maps are programmed into the DME chips. <hr></blockquote>

The stuff I've been working on allows real time adjustment of the ignition timing (along with many other items) of the stock DME. There are multiple adjustments in the DME for ignition timing: advance based on RPM, retard based on air temp, A/C on/off, and the maps based on idle/p artthrottle/WOT conditions.

Danno, for your kit you will still want a working air temp sensor (I can get you the Digikey part #) similar to the one in the VAF for DME input. The uses for this input are the air temp based ignition retard, warm start enrichment, and idle control valve duty cycle calculations. The DME also uses this to enrich/lean the fuel mixture based on air temp; I can null out that calculation to work with your MAP sensor input if needed since your MAP conversion should have taken temperature into account for air flow.

[quote] When the KLR hears knock from the engine, it tells the DME to dial back ignition 3-degrees. If the knocking continues, ignition will be turned back 6-degrees. Personally, I think this computer is limited since it really should be able to dial back ignition 10-15 degress if necesary. And it should be able to dial back ignition on a per-cylinder per-RPM basis. But these are ancient '80s computers and they were programmed with a fixed stock configuration in mind. <hr></blockquote>

I have scoured the code for the 951 DME and cannot find where the KLR signals the DME microcontroller to retard ignition. The DME does send a heartbeat signal back to the KLR and I see this in the code. I'll need to pull apart my 951 DME and look at the extra circuitry added due to the KLR input signal and see what it does.

I have been busy selling my house the past few months so my DME project has been on hold. I'm moving now so hopefully I can get situated and get the project back on track.

[quote] The second hard limit is your fuel system. We haven't found any official specs from Bosch on the flow rates of the stock Turbo/TurboS injectors. Imperical testing shows that the same part# injectors flow different rates between two different sets of injectors from two different people. Even when tested by the same company R.C. Engineering. However, numerous people have reported actual-use experiences of these injectors maxing out at 100% duty-cycle around 280-310rwhp. Depending up the other upgrades in your car (free-flow intake, turbo, head work, exhaust, etc.) this limit can be reached at around 13-16psi of boost. <hr></blockquote>

The only listing I've found for a 951 injector flow rate is here:

<a href="http://www.autospeed.com/A_0102/P_3/article.html" target="_blank">Injector Flows</a>

I'm assuming this is for the 951 non-S and have no clue for the fuel pressure used.

The air flow calculation done in the DME already has the injector flow precalculated into the equation so no hope of determining what Porsche thought the injector flow rate was (unless somebody has a map of the air flow rate of the VAF vs. output voltage at standard temp).

When you change the size of the injectors, it skews the load value that is used to control ignition timing, fuel adjustments, idle control, etc. This can be corrected.

PrerYDoG

Bump - I had a question up there.

Thanx

Danno

"I like the free flowing - restrictionless idea, but how bout them chips? Will their timing retard still be in effect? Would it be better to run without them? We'll there fuel maps even be taken into consideration? If I can replace the KLR for the upped rev-limit and remove the over-boost restriction, great, and leave the DME as is so that the timing retard won't reduce power..."

No you ALWAYS have to run with some AFTERMARKET chips. There's no way to you can use the stock chips with ANY upgrades. First is the overboost-protection that kicks in at around 13psi and prevents you from making power beyond this point.

Second is igntion. As mentioned in my earlier post, there is but ONE optimal ignition timing for each and every combination of air-temp, boost, load and RPM. Since you will be running higher boost, it is NECESSARY and IMPERATIVE that you have the ignition retarded from stock. If not, you will be in the knock/detonation territory and WILL NOT be making more power with less retard. So re-read my previous post on ignition timing:
[quote]"As a result, more ignition advance DOES NOT guarantee more power. Conversely, retarding the spark DOES NOT mean you'll lose power as well. "<hr></blockquote>

"Also, I recognize that there is efficiency restrictions on the current turbo and ignition/fuel system. What I'd like is a new turbo, exhaust upgrade, injector upgrade, FPR, Wastegate, boost controller and a Link Sys system. At this point I want to know that the Link sys is NOT the limiting factor (for boost, ability to add to fuel, or whatever reason)."

Yes, the Link MAP-sensor upgrade will not be a limitation whatsoever! At a minimum, all its settings can be put to ZERO and it passes all signals through unimpeded, thus if there's a limitation somewhere in the system, it's not here.

As mentioned in my previous post, the major limitations are the stock turbo and fuel system. As such, turning up the boost to 15psi will only give you some minor gains in HP (+15-20) because the boost is already dropping in stock trim. Increasing its maximum level will only have it drop from 15psi in the midrange down to 10psi at redline (vs stock 11 to 10psi drop). However, you can expect a SIGNIFICANT increase in mid-range torque (more below).

Also the fuel-system is the other major limit. On our development car, even with the fuel-pressure turned up, we are still getting 100% duty-cycle on the stock injectors.

"So it will be set for the basic booost and upgrades, but will still be adaptable up to 18 psi, upgraded turbo etc?"

Yes, the MAP-sensor is good up to 22psi of boost. To run this level of boost along with the significant increase in flow-rates, you'd need at least 55lb/hr injectors (65lb/hr would be preferable). The unit will only need minor recalibrations since the increased fuel will scale closely with the increased boost (you'll only need to turn down idle values).

We just got finished dyno-testing our 180K-mile developement car this last weekend. The initial run showed the typical aftermarket-chip extreme mid-range richness with dangerous high-RPM leanness. However, the torque curve was still 10% higher than stock and was perfectly flat from 3000-5250rpm. After several runs, we were able to get a flat fuel-curve dialed in at 12.3-12.8 across the board. This raised the torque curve up another 10% from 3000-4500rpm.

The car was extremely heat-soaked at this point and along with 180K-miles on the clock, a 20% torque-increase across the board compared to stock is significant. We expect cars with less mileage and better sealing to see 25% increases.

Our next dyno-testing and presentation should be at Bill's 'dyno' Mite day on 7/20 in the upper S.F. Bay Area. Come check out our test car and drive it back-to-back with your stock car. We may also be installing the first customer beta-tester at that time. Production kits will probably be ready at the end of July. Sorry for the delays, but we've had a problem simply BUYING these MAP-sensor upgrade boxes. Apparently another 'tuner' has gotten exclusive U.S. distribution rights to the MAP-sensor boxes and won't sell them individually, only as a completely bundled kit (at significant prices). But we have a source for them , hopefully.

TT - I sent you an email about having you burn us custom chips for this application.

Konstantin

the official BOSCH data for the 951 Injectors is 372cc/30 sec.
I do not know if this is rated at 2.5 bar or at 3 bar the 372cc/30 sec id absolut right it doesn't matter what other test says.

Konstantin