911SC Turbo

[iamchappy]

Thad, dont forget to give us the details of the drive.

[rfng]

Originally posted by sammyg2
Looks very similar to what I did, except mine is under the knee pad just to the right of the steering column.

running that tubing without kinking it is lots-o-fun, isn't it?
Going through the tunnel I was afraid it would rub against something and get a leak so I fished it through some 1/4" nylon tubing just for added protection in that section.

I have a spare 3" oil level guage that I plan to modify to hold my air/fuel ratio gauge that will take the place of my working clock.
I'm going to try and install the a/f guage inside the oil level gauge.
If I did it right it will look like it belongs there. If not, oh well.

Why would you do that, just attach a 924 booster brake tee and you can connect the line under or behind the gas pedal.

[tsuter]

Richard, My boost gauge measures boost only - not vacuum. So I hooked it to a source above the throttle butterfly in the turbo outlet pipe. Not sure if applying high vacuum (i.e., using the brake vacuum booster line) would affect the calibration over time? I guess its under some vacuum anyway most of the time. So maybe it would have been easier to "T" off the brake vacuum line.... if its safe??

[sammyg2]

Hmmmm, never thought of using the brake booster vacuum line.
I'm gonna go look at it this morning though, might be the way to go.
Yesterday I was fooling around in the engine compartment and partially kinked that 1/8" nylon tubing so I have to do some work with it anyway.
Thanks for the tip. Sometimes things are so obvious they are hidden in plain sight.

If I can just tie into the vacuum line in front instead of running that stupid tubing all the way to the back I will do it.
I'm assuming there isn't any reason why the signal there would not be accurate?
I can't see any kind of bleed system on it or anything but I've never played with it before.

[rfng]

Originally posted by tsuter
Richard, My boost gauge measures boost only - not vacuum. So I hooked it to a source above the throttle butterfly in the turbo outlet pipe. Not sure if applying high vacuum (i.e., using the brake vacuum booster line) would affect the calibration over time? I guess its under some vacuum anyway most of the time. So maybe it would have been easier to "T" off the brake vacuum line.... if its safe??

Yeah, I ran it that way for about 2 1/2 year and 70K miles. Not a problem, pressure always equalizes, so whether it vaccum or boost you will get an accurate reading. Go to the junk yard look for a 924 (I don't have the part number) and take the t off of the brake booster. The t portion is small you can just slip a piece of vaccum line over the plastic tube kit, no clamps necessary, just make sure it slides in about 1"-1.5".

[rfng]

Originally posted by sammyg2
Hmmmm, never thought of using the brake booster vacuum line.
I'm gonna go look at it this morning though, might be the way to go.
Yesterday I was fooling around in the engine compartment and partially kinked that 1/8" nylon tubing so I have to do some work with it anyway.
Thanks for the tip. Sometimes things are so obvious they are hidden in plain sight.

If I can just tie into the vacuum line in front instead of running that stupid tubing all the way to the back I will do it.
I'm assuming there isn't any reason why the signal there would not be accurate?
I can't see any kind of bleed system on it or anything but I've never played with it before.

You tap into it around the gas pedal, there a line comming in. Its inside of the car. As for a mount I used a old clock gutted it and cut a hole in the center, so it would fit into the stock clock position.

[rfng]

As for your lag and fuel system. Part of you lag problem is :

1. The pipe BAE used from the turbo outlet to the throttle body is too big. I think BAE used a 3" pipe, you can use a 2.25-2.50 pipe which will reduce the volume of air required to fill the engine and should knock off a few hundred rpms.

2. You are not giving it enough fuel. A 3.0 engine requires at least 2 csv or 1 for each 3 psi to run properly. The closer to rich you run the more responsive the turbo will be, as the increase in fuel will cause a better and larger burn which will flow more gases to spool the turbo up faster. However what you guys are doing may work but you are only compesating for fuel under boost and really not metering it according to throttle position and boost. A boost pressure regulator on the main fuel line will not work, as it will not compensate or raise the fuel pressure enough. CIS relies soley on fuel pressure and not duty cycle of the injectors, so a large increase is required, ( but the contol pressure also rises proportionately, so the plate does not rise proportionally to fuel it.

However there is a limitation as to how much you can raise the pressure and have the car still run correctly. That why 270-300 horsepower is the maximum, you will run out of fuel and must modify the system extensively. Even with my mods, I would run out of fuel at about 13 psi and the fueling was marginal.

The detonation at 6 psi is because you are running too lean. You need to run a little on the rich side as this is an air cooled engine and must use part of the fuel to reduce cylinder temps.

[tsuter]

Notes: The turbo outlet pipe is 2.50 ID to the throttle body. It uses a 2.25 to 2.50 reducer to connect to the turbo outlet which is 2.25. The turbo inlet pipe is a 3.00 ID all the way to a 3.00 inch elbow into the turbo which is 3.00.

Drive test results:

a. The Tial BOV is very quiet. You can hear a "pssssst" on each shift under boost but it is not loud at all.

b. I ran the TurboXS MBC closed and recorded 6psi on the boost gauge. Tialco Wastegate has the .4Bar spring. Ramped in third gear 2500 to 6000 - no issues noted. Boost begins at 3000 and is maxed by 4500. Function of the compressor as my Fabspeed exhaust is 4.5inches straight out right side!

c. opened the MBC four turns and recorded 9.5psi on the boost gauge. ran a second time and immediately got a very loud "poooof" type noise. Like VERY loud. It was a "known" sound and I had blown the silcone bonnet clamped to the top of the throttle body with the turbo outlet pipe off. No big deal but it was really tight reattached on the side of the road and lowered boost.

d. Opened MBC 3.25 turns and recorded 7.5psi on the boost gauge. Third gear WOT 2500 to 6000. - no issues noted so I'm leaving it at that setting.

e. Note: Enrichment CSV opens via the closing of the Hobbs NO switch at 3.0psi boost. You definitely know when it opens as you feel more power (at least I think I feel more power)

For $75 and three runs, I may even visit the local chassis dyno just for kicks and see where things stand at 7.5psi with enrichment at 3.0

[tsuter]

And the wide angle view - home from the check out drive. No nasty fuel leaks!! Hopefully the last significant motor mod has now been completed with the Tial BOV.

Well maybe have to think about two stage enrichment. 3.0psi and again at 6.0psi - like the old days. Maybe even put the second one in that airbox place right below the TB and trigger it at 3.0 and the upper (existing) one at 6.0??

[sammyg2]

LOL it never ends.
How hard does it pull at 7.5 and at 9.5?
I image it's plenty strong.

[tsuter]

Not sure I could tell any big difference from 7.5 and 9 as third gear goes pretty fast but the big "POOOOF" when the silicone bonnet blew off at 9psi sure got my attention. That one really should be aluminum I think - well that's another project.

I have to drive some more over the next few days - make sure I have no detonation and then see about a dyno run.

[iamchappy]

I would think a metal cap, carbon glass or strap across the top of the bonnet bolted down or held on by springs could keep it in place.

[ohecht]

I have been following this thread as a potential project for the future, and I have a general question for all turbo setups:

Is it hard to constantly take the turbo itself out for upgrades, service, etc.?

There seems to be a lot of fine-tuning and regular maintenance on turbos, and almost every exhaust component on every car I have had has become "permanently" installed due to heat, corrosion, etc.

I have never been able to "casually" remove an exhaust item without worrying about broken hardware, cutting things, etc.

When I just look at the connections between my SSIs and the 2-in, 2-out muffler I have now, I don't see it coming apart easily.

What's the secret, or is it sometimes a huge pain?

Thanks,

Olivier

[sammyg2]

I can have the turbo out of the car and on the bench in 10 minutes.
The rest of ther exhaust take a little while longer but not much. A good high temperature never-sieze is your friend. I use nickel-eaze by lubriplate.
With htat you don't have to worry about broken stuff.

[tsuter]

1. My turbo has never had maintenance in 45,000 miles and never been rebuilt. They are very reliable however Oiling is critical for a DIY install and proper cool downs.

2. Removing the turbo or muffler/exhaust has the same challenges re: seized bolts etc. as any NA car but it doesn't need it anymore often.

3. All the other stuff - BOV, Wastegates, Inlet and outlet pipes, Enrichment injectors, switches are simple bolt on devices anyone of which can be removed in a matter of minutes for maintenance or evaluation however typically nothing would be required.

4. More typical is as a DIY install, the OWNER keeps wanting to tweek and improve the configuration and this is the normal reason things get taken apart.

5. If your car is CIS, you need to be AN EXPERT in K Jetronic because when you add an after market turbo you will need to understand in detail how fuel gets managed. If you can't tune your CIS when the car is NA you WON'T be able to tune it when turbo'd. And neither will anyone else!!

6. You will also need to be comfortable with getting rid of catalytic converters, air injection, exhaust gas recirculation, and deceleration valves, also O- sensor duty cycle modification, mechanical ignition timing, and ALL vacuum hose applications.

7. Backdating heater components to make space is required.

8. Air conditioning systems are not affected and don't need to be moved.

9. You should also not care how much it costs, or wonder if you should just swap in a 930 motor instead not because it costs a lot (it doesn't) but that should not be relevant to the decision process. A DIY turbo is UNIQUE project, a 930 motor swap is not. Are you a leader or a follower? Do you care?

In general as turbocharging a NA car is a significant modification, you need to be very well versed with how to maintain and tune your NA car first. Turbocharging is not a 3-4 day project. Getting it working correctly and reliably is more of an art and that has to be a challenge that you want.

Oh and lastly, you need a good jack and jack stands.

[ohecht]

The project aspect and tweaking over time is part of what I would look forward to. I am very comfortable with CIS maintenance, repair, and modification, but I would probably go with EFI first.

How would turbocharging work with my stock 9.3 compression? Is that feasible with the 7-8 psi you guys seem to be working with? I do not want to hasten the wear on my engine, but I imagine I would retain driveability in the lower RPM range if it is doable.

Olivier

[rfng]

Yeah thats the problem with boost. On my kit it started at 6 and eventually ended up somewhere between 9-13. As the motor got more tired, I compensated by turning up the boost. With the right distributor you can run 7-9 psi no problem non-intercooled.

The intercooler won't allow you to run a substantial amount of more boost, as it purely a function of the ignition timing (once the pressure get to certain point you have to move the timing), however it will give you a slight increase (smoother delivery) in horsepower at the same boost level. Sorta like a sewing maching.

As for the longevity of the motor, if you are worried (not Sammyg2) then my suggestion is that you leave it stock put a set of ssi's and be happy with 15 more horsepower. A turbocharged engine is not for the faint of heart. Even a low boost motor can blow if you run it hard enough. I've seen full built 930 engines let go after about 40K, it depends alot on your foot control. Even the guy who bought that tuner's 930 I forgot his name, was racing everything in site and guess what the engine let go.

Eventually if your car is putting out enough horsepower generally over 300 then the reliability goes down. Once you get to 100 plus hp per litre thats what you get.

On my car I started with a tired 3.0 and put about 70K extremely hard miles on it to check the reliability. It didn't let go but the valve guides and blowby were so bad it needed to be rebuilt. When I took it apart the pistons, barrels and rings were shot, valve guides gone, and the head gaskets where gone, but I expected that since the motor wasn't that healthy in the first place (what do you expect with motor with 180K plus).

As for the compression ratio porsche's rating is a little high, it closer to 9 than 9.3.

As for a distributor I have turbo one you can try before you buy Sammyg2. Its been recurved has a late advance unlike the 80 plus SC distributor which starts to advance right off of idle. It also has 5-7 less degrees of total advance.

[ohecht]

Thanks, guys. I will keep collecting information. I already have SSIs and the Stock SC is running great with maximum advance and fuel right now. The car already feels like a go-kart to me, so I would try to be happy with less 300 hp. Anything more than that, and I would probably hurt myself before the car!

The motor has 120k on it, and I suspect it was rebuilt at one time. All cylinders had 180 psi compression last time I checked and it consumes almost no oil whatsoever (~1 quart every 3-4 tankfuls). MPG has suffered at around 10 since I set the mixture to 3.5% CO and 35 degrees total advance, though.

I am looking forward to seeing the final versions of the DIY turbo kits in development now, and I will keep my eyes open at Hershey. What turbo would you recommend for 5-6 psi on a stock 9.3-1 motor?

Olivier

[tsuter]

If I was buying a new turbo for a 3.0Liter SC DIY install today I would get a TO4E in 54 trim.

turbos and corrected air flow

[ohecht]

Sorry last question, as I read that thread but was confused by the considerations for turbo selection:

What makes the TO4E in 54 trim such a good match, and how does the trim affect things? I read about the "efficiency islands", but I do not fully understand what the axes of the graphs are telling me. I need to understand more about how a selection affects the point when the boost comes on, etc.

Thanks again,

Olivier