Francisco Martinez

I actually meant to open a new thread on this........
I have searched and have becomed very confused with the tuning options and the Fuel Enrichment for the turbo 3.6.

First, could someone clarify is the turbo 3.6 has a a fuel enrichment circuit that no other CIS turbo cars have? What exactly is this fuel enrichment doing, what signals control it or is it just a boost vs rpm map ?

If the above true, what is the recommended tunning options to apptoximate the ideal/safe AFRs specifically for the turbo 3.6 rather than the 3.3s?

Is it still the 3% CO + unplugged O2 sensor option or does this not hold true for the turbo 3.6?

Any additional information welcomed,

Thanks..
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fritz k.

hi,

both 3.3 and 3.6 turbo only have full-load enrichment controlled by the warm up regulator.
If the boost pressure exceeds 0,25 bar control pressure is lowered from 4.5 to 3.2 bar (3.3 litre) resp. 2.9 bar (3.6 litre).

lowering (fuel-)control pressure causes richer AFR.

fritz

Turbohead

The 3.6T has a different enrichment control unit map than the 3.3 ( underseat)

The unit enriches mixture upon partial and full throttle by signaling WUR
Elliot

Francisco Martinez

I am sure I am not discovering something new but have to ask, given all the issues regarding keeping a nice AFR across the board that I have read. If the Fuel Enrichment sends a signal to the WUR, I would guess based on a map for open loop and RPM/TPS/Boost for closed loop. Has anyone experimented with a signal conditioner such as the ones provided by Split Second?

http://www.splitsec.com/products/psc1/PSC1001.htm

KeithC2Turto

It is my understanding that the 91-94 acceleration enrichment circut is the same. And that it only works under cold running conditions and just for a short time after start up. It might be possable to trigger it for more fuel by grounding the right terminal. It bassically moves the frequency valve to 75% if I recall correctly.

I have heard from one good source that the 3.6 has different injectors that flow a little more at the same injector pressure and it has a different metering cone profile that the metering plate rides in.

On top of this the 3.6 WUR seems to actually have higher control pressure to slow the metering arms progression which makes sense if more fuel is delivered via larger flow rate injectors. What is strange is that if you look for replacement 3.6 injectors they seem to be the same as 3.3's I have heard.

From what I know about CIS operation this approach makes a lot of sense.

I belive the 3.6 can support up to about 425chp (stock being 360) with out much being done to the fuel system but you will want to check it on a dyno or with a wide band. Lowering control pressure on boost might take one to 500chp. If that dose not work you might try shiming the Fuel Distribuitor. If it dose not respond to that the fuel pumps probably can not hold system pressure up under high duty and a higher spec 040 Bosch race fuel pump or such might help.

Francisco Martinez

Thanks Keith,

You have actually helped me out somewhat, the thing is that I know the 3.6 has some changes to it in the fuel delivery but just don't know the details. I have a manual boost controller and a Zeitronix installed (Wideband, Boost, RPM with datalogging) but do not dare to turn up the boost until I understand how to go about the adjustments. I don't plan on going over 1 bar.

KeithC2Turto

Old school was to adjust the base CO to about 3% which dose two things. It gets the AFR to one more ideal for acceleration off idle and it gives a little more fuel up top to support higher boost.

When doing this many just unplug the 02 sensor.

I have an idea I was never able to try as my C2T was converted to a Euro Fuel Distrubuitor by the previous owner.

The though is one could put a dwell meeter on the frequency valve and when fattening up the CO could watch the duty cycle. The duty cycle typically runs from 25% to 75% with 75% being more fuel, 50% being defalt, and 75% being used for the cold start acceleration enrichment.

My thinking is to use the duty cycle to adjust the Co unitll it is close to say almost 25% at the frequency valve.

This way when you accelerate or go to WOT the Lambda correction will fall off and the duty cycle will bump to 50% and add some fuel for acceleration and boost.

I do not know how much fuel this will add but is will let the Lambda function keep MPG and emissions in a good place at idle and cruse.

Last note, the stock turbo K27-7200 is at its efficency limit on stock 3.6 makes. At most it can support about about 365whp and at that point it is making a lot of heat and boost will start falling off with rpm increases.

A 3.6 responds very well to a larger turbo and straight through style muffler after the turbo and about .9 bar boost.

I would do this, fatten up base Co and then increase boost untill my AFR's are at about 11 to 11.5/1 AFR at about 5500rpm.

I would put a GT 35 and play with the hot side AR to get the low end response you want. But if you want to stay more original the HF turbos are an alternative. They will boost early but the hot side is on the old tec side and restrictive for a 3.6.

Just my opinion.

Francisco Martinez

Thanks again Keith..I have no problem moving to a GT35 if the flanges can bolt on with no mayor issues. I was actually getting ready for an HFS, but it I can get the same (or more horsepower) with less engine effort, I will go with a GT35.

KeithC2Turto

I have not done this.

The GT35 is usally had with a T3 flange that should be a bolt up. I think the muffler, compressor in and out might have to be accomodated though. Also the oil line needs to be restricted down as a ball bearing turbo can not use as high of oil pressure.

Might check with these guys: http://www.turbokraft.com/catalog/in...c21bbe9fd496bc

Severial owners have gone with the K27HF turbos that are a K27-7200 with a larger compressor and been happy with them on a 3.6T on the street. The factory put the K27-7006 on that for all purpose is a 7200 with a less restrictive hot side for some of there special C2 turbos. These are direct bolt on's. I had a K29 on mine for a while and it bolted up except it had a larger compressor housing and the motor schroud had to be modified.

That is about the limit of my knoladge.

cobalt

The duty cycles for the 3,3 and 3,6 are different although I would have to look up the info.

i am confused regarding your comment on euro fuel head. I know the old SC's and 930's had a different fuel head for ROW vs US models although I believe the 964's were the same for both versions.

KeithC2Turto

Someone spend a lot of money on my car before I got it. At one time back when many tuners thought the non lambda FD had more flow potental. Further that the later smaller Fuel Distribuitor to injector lines on the Lambda cars and the injectors were all belived to be restriction over the euro or non-Lambda FD's. Thus, they 'upgraded my system to a euro system'.

From what I think I know now, that was a misgided attempt and the Lambda FD's have more delivery potental.

As to the duty cycles of the frequency valve. I can not think of any reasion to make any changes. Most of the time the DC is determined by the base CO setting and the Lambda computor is going to adjust around it to achive the goal AFR. Then, with a given throttle angle the Lambda is turned off and jumps to a fixed position. I belive that is 50% but not sure.

Anthony,

Can you tell Francisco how you got to 430hp (chp or whp?) and if you needed any thing on the fueling side. Turbo, exhaust, boost...?

cobalt

So they used the older 930 fuel head If I read you right. AFAIK the fuel head on the 3.6 should flow more fuel than the earlier 930 ROW fuel head.

I would have to look up the specs but IIRC the 3.6 enrichment like the 3.3 964 has 2 adjustments On the 3.3 it changes the enrichment twice depending on throttle permission on the 3.6 it remains the same for the second position. The info is not clear to me without doing some research (it has been a while since i looked into this stuff) I will see what I can come up with I have all the CIS manuals for these cars at home.

My car is actually running 384 RWHP in its current configuration. I can't change my signature without eliminating lines so I leave it.

Simple bolt on mods starting with a clean strong engine. 1 bar spring, B&B headers, HFK27, Billet BOV, Drilled airbox with K&N filter, cat delete, magnaflow muffler the 430 calculated BHP was same setup with cat in place. Most importantly the car was dyno tuned. There is no need for fueling so long as the car is properly tuned. these cars should be good up to 400rwhp without the need for additional fueling although those numbers would require cam work and to me the car is good enough as is. There will always be a faster car, I don't need to be the fastest.

Car is much more comfortable to drive with the HF and cat delete. No more on/off throttle response, much more like a n/a response throttle. power comes on strong with full boost at about 3000rpms. It was full boost at 3250 with cat. I don't have any current charts I could post but the AFR's are as good as you can get for a CIS car. I monitor my AFR's using an in your face gauges display which gives me peak boost readings along with maximum intake and exhaust temps.

Otherwise the car is stock. the internals are all the same and the car is as strong as any 993TT or 996TT.

turboholic

Anthony, just curious, I also use inyourfacegauges AFR and Boost monitoring in my car, I plan to get me a PLX EGT sensor kit, where did you place your sensor and what readings do you get on WOT in a higher gear? Are you happy with the EGT sensor? With 1bar, does your car exceed 900C° on a longer WOT run? Also would like to know where do you measure inlet air temperature, between the intercooler and throttle? I have very similar mods like you in my car except that I have a 7006 turbo and GSF headers with cat delete and stock muffler.

cobalt

My sensor is placed right after the turbo around 3" back from the flange. So far i have not seen temperatures running anywhere near 900 C even after prolonged on boost runs. I did a 60-140 run the other day and my EGT was around 1200 Degrees F. IIRC the highest temperature i have seen was about 1400 F after driving 300 hard miles with a group of other Porsche's on a hot summer day. So about 250 or so degrees F below your 900C.

The intake sensor is placed in one of the bungs in the I/C along the top. It is too difficult to mount it closer. Might not be the most accurate but it gives me a relatively good idea of temps. I usually don't monitor my intake temps as much unless it is a very hot day. I find I switch between AFR and EGT 90% of the time. I usually check up on my boost to verify I don't overboost but it has so far never been an issue. On average I run between 13.8 and 14.8 of boost depending on how many gears I run through and how hard I press.

Metal Guru

Anthony, what do your AFRs look like from 3000-6000 rpm? If I understand right you are running an HF turbo. Do you have an adjustable wur?
Thanks.