Turbo Carrera making real progress, question for those who've been there...

[Colby]

The turbo Carrera is coming along nicely. I have the early style heat exchangers plumbed up to the turbo (I found the perfect compromise. Everyone said T3 was too small, yet I don't want bad lag, so big T4's were out, so I found a small T4; .8 A/R hot, 60 trim compressor). I have a deltagate wastegate (5lb. spring) on the way, and a tube right before the turbo for it to be welded to. I have the intercooler plumbed up to the turbo and MAS, and I have the air filter plumbing done. I am in the process now of finding a BOV (I don't need, or want, a $200 HKS. A 1st gen Talon one would work fine, and I should be able to get it for $30).

Here are my current snags:

1) I don't think I will be able to use gravity oil drain. The turbo is mounted in the back, about where the 930's are. I wanted to drain into the timing chain cover, but I don't think that will work (not much space, steep angle). So I am looking into a oil accumulator and pump setup. Can anyone explain how this setup works on the 930? What can I use for a pump (electric, or I've heard of one that runs off the cam?)

2) I am still not sure what to do about fuel and timing management. The options seem to be:
Protomotive Chip: $550 for the chip, $550 for the fuel pressure regulator which you must use to use the chip. Not adjustable, still uses stock MAS. But a tried and true system made specifically for turbo conversions.
Huntley Racing MAS and fuel computer: $1200 for the whole setup. Adjustable, uses a higher flow hot wire MAS, only controls fuel, not timing. Not made specifically for turbo conversions but they said they've used it on them before.
Apex'i AFC (fuel) and ITC (timing). About $500 for both. I used these back in my rice car days. Great adjustability of both timing and fuel. Main flaw is I don't know any Porsche that uses them, and don't have any schematics on how to wire them up. I don't even know if they'll work. Would be nice if they did.
Various stand-alone or piggyback systems (UniChip, etc.). Cost varies from $500-2000. Some use speed density or manifold air pressure, which would be nice, but I am hesitant to totally replace the factory DME or get a TOO complex of a fuel system; tuning could become a nightmare.

3) Boost control. What is the stock compression ration of a non-euro spec '84 Carrera? What would ppl vote is a safe, intercooled boost to run? I keep hearing anywhere from none to .5 to .7-8. The wastegate has a 5lb. spring which equates to about .35 bar. That is probably too low, so I suspect I will need to run a boost controller to allow more. I am familiar w/ these (manual v. electronic) from my rice car days. I may just run .35 bar for now.

4) Fuel system. At what point are bigger injectors recommended/necessary? What about fuel pumps? If I replace the fuel pump (I hear SC and turbo pumps are the ideal swap), are there two pumps? If so which one do I replace?

With any luck I will have this thing done in the next couple months. I only work on it on the weekends, and am always waiting for new parts to arrive. Things like T4 turbo flanges and oil line adapters are things you don't think of until you need them and set you back a week while you wait for them. But so far my costs have been VERY low. Buying everything used or off Ebay. The biggest cost will be the fuel management, but that's one area I don't want to skimp. Once I get it all together I will take pics.

If I get it put together but still only have the stock DME, can I drive it if I keep the boost down to say 3-5psi? Will the stock computer be able to supply enough fuel on its own for that? Or should I am playing w/ fire if I try that?

Colby

[beepbeep]

BOV: Use second hand Bosch recirculating BOC off a Saab 9000 Turbo...price: 10-20$...easily found on a junkyard. Works perfectly, ditch fancy 300$ "open" BOV's.

About boost & fuel issues:

You can probably run up to 0.5 bar with current ECU (your car has Bosch Motoronic and not CIS, right?) and injectors if you run intercooler.

Of course, use lambda-sensor to check mixture at all loads. Also, get yourself one of those raising-rate fuel pressure regulators. That means that if your boost is 0.5 bar 1:2 RR FPR will raise fuel pressure with 1 bar, allowing injectors to spray more fuel on boost.

C/R is probably the biggest issue...you could try to modify SAAB APC-computer with it's knock sensor and let it control the boost trough pulse-width modulation of valve on wastegate's pressure-line? (But Porsche-engines are noisy which could fool piezo knock-sensor).

APC works this way: you have your WG set at fool-proof pressure where detonation cannot occur under any circumstances...say 0.35 bar. If pinging is not detected by piezo-mic in engine head, electronicaly controled valve going to WG-bell will be PW-modulated to allow more boost. As soon knock is detected, valve will shut to decrease boost to safe level.

Electronic circuitry in APC is tuned for 4-banger watecooled head with hydraulic valve-lifters, but it might work on 911...just might.

[beepbeep]

Fuel pressure regulator chart:

[The Sign Guy]

Colby,

Check out the SDS system. I have one for sale, and there is a link in my ad where someone used this exact system to do what you are trying to do.

Click on this link to look at my ad and find the link to the TURBO.

Thanks, Kevin

[Tinker]

Colby,

As for scavenging the oil from the turbo, I have also seen it drained to the timing chain cover on aftermatket turbo conversions. But as you have stated, you really have to rely on gravity. This might be your only choice. On earlier motors with a sump cover (Since you post implies a Carrera case, probably no sump cover) I have seen a fitting welded on the bottom cover and a stainless line connected to that. That would seem the best solution other than the factory design or mounting an electric pump somewhere.

A friend of mine has done a few of these (added a turbo). One of them was on a Carrera motor without an intercooler. The guy is running a Motec system and it runs good and strong....for a few runs. Without the intercooler, it really starts to cook the mixture and he has to back off the timing and boost to keep it from melting down. I believe it has 9.2:1 static compression ratio and is runnong between .5 - .7 bar boost. The motor is stock and was not rebuilt or touched prior to adding the turbo. It has held surprisingly well. This one is draining the turbo oil to the chain cover.

Post some pictures and keep the list informed.

Tinker

[Colby]

Beep: Yes, a boost sensitive FPR is definitely on the list. Which I get is still depending on whether I let Protomotive stick it to me w/ their $600 FPR, or I get one elsewhere for $150 (how different could their's be to justify the cost???). My dad tried using a knock sensor on his 3.0L race motor w/ an Electromotive fuel management. It was too noisy, so as much as I'd like to have one, I think I will have to rely on the gauges. Which brings me to the next thing; gauges. I will definitely have an EGT, A/F, air intake temp, and cyl head temp gauge. I think these are your best warning that something bad is about to occur. Re: the BOV, I considered the Bosch recirculating unit. I don't like how it is connected to two rubber hoses. I would prefer one which is welded on at one end. That is a more solid mount, and allows me to run open if I choose (which I will if I keep the MAS at the factory location. If I ever mount an aftermarket MAS before the turbo, then I will have to have it closed loop).

Sign Guy: Tell me (and everyone else) more about this system. Does it replace the Motronic setup, or piggyback? Is it fully programmable, and if so by laptop? Is it hard to setup? Does it use the factory coil, distributor, etc?

Tinker: I would really like to plumb it into the timing chain cover, but it sure is a tight fit. If not, I will have to resort to a pump setup. Do you (or anyone else) know how the 930 setup works?

Colby

[5axis]

http://www.sdsefi.com/

david 89 turbo cab

[dean]

On a 930 there is a cam driven gear pump. It sucks oil from the turbo accumulator tank. Then the pump dumps the oil into the oil tank.
Dean

[beepbeep]

1. SDS is really nice system...

2. There's nothing wrong with recirculating Bosch BOV...i've run those up to 1.4 bar, despite shoddy connections.

3. Progressive FPR *shouldn't* cost more than 100$...notice that i'm talking about *progressive* which are raising the pressure more than boost. Ordinary linear ones can be had for a song.

4. 930 has a oil-pump on left upper camshaft sucking oil from turbo...a bit of an overkill...gravity-drain should work.

Please keep us posted on your results!

Good luck!

[RarlyL8]

Colby - I just took (and posted) a few pictures of my 930.
Here are a few more that may help you:

On the drivers side of the engine you can see the turbo oil scavenging pump that runs off the right rear cam. The steel line connects to the oil accumulator tank. Oil is fed by a bajo fitting off the engine oil sensor located at the center rear of the engine.



This is the accumulator tank. Connects to the bottom of the turbo, pump sucks out the oil, line on the left runs to air breather to stabilize pressure.

JOHN WALKER - remember the bracket I asked you about? This is it - the one that was fabbed because the stock unit would not fit the K27-7200 correctly. Don't know why, it just would not line up on this Euro exhaust.

[RarlyL8]

That middle picture was upside-down. Lets try again:

You would have to machine the camshaft to accept this oil pump. Not something I think you want to do.

I'd like to hear more about the gravity drain into the bottom sump plate. Will this work well long-term? Does the oil back up at all?

[RarlyL8]

Here is a better picture of the rear turbo oil scavenging pump:

[RarlyL8]

[Colby]

My main concern w/ using a standalone system, such as SDS, is the little things. Like, what about the tach; will it still work? And doesn't the Motronics use a ton of variables (throttle position, etc) to determine the fuel/timing? SDS doesn't, does it? It just seems "safer" to use the tried and true Motronics, then tweak it with a piggyback system. But then again, I have never tried a standalone setup, so this could be just feared instilled by ignorance.

Colby

P.S. Those pics are VERY helpful. Looks like I could use a 930 oil accumulator, then design an electric pump (fuel maybe?) to do the sucking. I hope I can avoid that and get the gravity drain to work.

[beepbeep]

SDS uses a number of sensors to determine mixture.

Those are most important:

1. MAP-sensor (measures absolute pressure in manifold)
2. Crank-position sensor (measures RPM and exact position of the crank)
3. Throttle-position sensor. (measures how much throttle is depressed)
4. Lambda-sensor for closed-loop

This is how things are done on all modern cars and in certain areas, SDS is more advanced than Mo(to)ronic...

First of all, it doesn't need AMM, it can determine amount of air sucked into engine by measuring RPM and manifold pressure. Whit other words, there's nothing between turbo intake and filter...you can have straight pipe.

SDS is also *combined* fuel and ignition , so you can throw away ignition dizzy. It uses so called "direct spark", so each spark-plug has it's own coil...

Advantages are numerous....etc. etc.


However, you can start with Motoronic and see where it gets...piggyback systems are just band-aids.

Cheers!

[RarlyL8]

Colby - call up the add on turbo shops and see how they handle the oil. I'm thinking that you could use a pump such as those made for pre-oiling and post-oiling turbo timers.
On the other hand, if your turbo is mounted as high as a 930's AND the gravity system works long term on other transplants............
Need to find out from those who have done this.
Tinker?

[930fan]

I have no first hand experience on this subject but I have done some research on this for a future EFI conversion on my 930.

1) Gravity drain would probably work with a Garrett turbo. KKK equipped 930s that convert to Garretts' are required to put a restrictor in their oil return lines to control the flow due to the Garretts flowing much more oil than a KKK. I think your experience with rice cars would show that gravity drains work perfectly well on those cars

2) I would go with a Unichip. It can vary fuel and ignition parameters by +- 50% and has 400 mappable points. Advanced versions of the Unichip can also control boost, additional injectors plus have two programs for low and high octane fuel. It has been proven to work well with Motronic but the biggest advantage is that you don't have to muck around with mapping startup, low load and warm up maps which are the biggest headache of installing a stand alone computer. Contact an installer and talk to him. It will also be cheaper and more flexible than an afc/itc combo (a lot more mapping points)

3) Go with an electronic controller. They can get the boost in quicker and control it better plus they have an overboost cut as well as altitude compensation. I would suggest the blitz sbc-id. The Apexi unit can be made to work with a Motronic too.

4) According to the SDS site, a 350hp 6 cylinder engine would require 40lb injectors (420cc) to supply adequate fuel at 85% duty cycle. As for rising rate regulators, bear in mind that it takes a 4x increase in pressure to double flow so it's a poor band aid to increase system capacity. I don't know what the standard flow rate of your Carrera injectors are but if insufficient, you could either get 6 new 40lb ones or plumb some additional injectors after the throttle body.

As for pumps, the twin 930 pumps are excellent. Apparently, HKS rebadges these pumps for their own high flow kits.

Hope this helps. YMMV

[Colby]

Gravity drain will work, but two things concern me: 1) the return tube will only be about 2" long, and 2) it will be at about a 30deg downward, the about 45-50deg inward at the timing cover chain. Usually gravity drain works best with longer plumbing and with better angles. But as you said, the Garretts flow oil better so it may not block up as bad as would a KKK.

I agree w/ your assessment of piggyback v. standalone computers. Seems like a lot less headache (why not let the Motronic system already in place do most of the work, then modify the end result w/ a piggyback).

I will have an electronic boost controller eventually. I plan to at first just run the WG straight to the manifold. 5psi is a safe place to be while I work out the other kinks.

I read SDS's site last night and I too was shocked by what they say about FPR and fuel injector size. Stock Carrera injectors are 22lbs. Most ppl say if I turbocharge to bump up to 951 injectors, which are only 28lbs. According to them I need to double my injector size. That seems pretty huge. They also discourage the use of boost sensitive FPR which is contrary to what most other's say and do. Hrm....

Yes, I have heard the SC and 930 pumps are the hot setup. I don't know if I have to replace both or just one though...

Colby

[dean]

When I put the 930 motor in my SC, I just added a turbo rear fuel pump. I kept my stock fuel pump up front. It runs great.
Dean

[tbitz]

If you don't mind a little soldering then the "megasquirt" is a cheap ($100) fully programable ECU. I will be using this in my CIS-to-EFI conversion.

Check it out at:
http://www.bgsoflex.com/megasquirt.html

Ben Wills already has this installed in his 911 and is in the tuning phase. Check out the end of the "CIS to EFI" thread on Pelican.