Ignorant 930 turbo questions::

[THECARREAPER]

Hello. Had lots of cars, and lots of 911's/ This is my first turbo, which I purchased from a Pelican a few months ago.

Car has only been driven 3 times, and has been stripped for a repaint, headliner, new glass, ect.

I have some questions that I cannot seem to answer with the "search" feature:

1A) I would like to add a air / fuel ratio meter. Where is the best place in the exhaust to drill and install one?

1B) Any recommendations on what to buy, and from whom?


2) My blow off / waste-gate thingy has the upper line vented to atmosphere. my friends 1980 Euro turbo has a very different installation. His install has a tube that goes into the muffler, mine has a big pipe and two smaller lines.

This car was under the care of Mike Callus at Rennsport. I have receipts that total over $40k for the AC upgrade, 3.5 Liter turbo engine rebuild, and the trans-axle and LSD rebuild. I am really happy with all the hard work they put into this car, and I do not want to hurt the car out of my ignorance. The tub is a 1974 VIN. the engine is a 1982 turbo with 964 cams, giant twin plugs heads, and other stuff that i still don't know what the hell it means.




I know my CIS was modded for more power, but how much power can a 3.5L make on CIS? Ballpark?



Thank you for any help, and your patience.

[Norm K]

Originally Posted by THECARREAPER

1A) I would like to add a air / fuel ratio meter. Where is the best place in the exhaust to drill and install one?

1B) Any recommendations on what to buy, and from whom?


2) My blow off / waste-gate thingy has the upper line vented to atmosphere. my friends 1980 Euro turbo has a very different installation. His install has a tube that goes into the muffler, mine has a big pipe and two smaller lines.

First, congrats on your new car!

You'll likely get some varying opinions/advice - here's mine.

1A Post-turbo, for sure. I have mine pre-muffler, which I think probably offers the most accurate readings, but does expose the sensor to more heat than a post-muffler location. So, post-turbo, pre-muffler.

1B Depends a lot on what you want out of it. If you want it for hard-core tuning purposes, with logging capabilities, you'll probably want to look at Innovate's LM1. If for more basic tuning and monitoring purposes, you can save $$$ by using something from AEM, for example. In either case, absolutely select a Wide Band model.

2) That's your waste gate - your blow off/recirculation valve, is somewhere under or near your intercooler, depending on whether it remains in stock configuration or if it's aftermarket. Your friend's car likely retains its factory euro-muffler, which vents the exhaust from the waste-gate into the muffler to, you guessed it, muffle the sound it creates. Venting to atmosphere is not only okay, I think you'll find it's the preferred method for most folks here.

Norm

[oilonly]

Nice car. nkowi answered your questions. As far as AFR gauges go I amusing the WEGO IV. Cost a little more but easy to set up.

[mark houghton]

Originally Posted by nkowi

First, congrats on your new car!

You'll likely get some varying opinions/advice - here's mine.

1A Post-turbo, for sure. I have mine pre-muffler, which I think probably offers the most accurate readings, but does expose the sensor to more heat than a post-muffler location. So, post-turbo, pre-mufflerNorm

Uh, Norm: Wouldn't you say that 'post turbo' and 'pre muffler' are the same things? Just pulling your leg

Without a doubt, it should be installed post-turbo, but how far 'post' is the question. Me, I installed mine post-muffler, about 14 inches north of the tail pipe opening. I really haven't seen any issues with ambient air causing a false lean reading, and certainly not an issue once the exhaust gasses are blasting out the end. At idle might be the only risk of false readings, but again it's been working fine for me. And I don't have to worry about toasting the O2 sensor from the extreme turbo heat.
And also correct, don't confuse your wastegate with a blow off valve (stock 930's don't have blow off valves, but rather a boost recirculation valve). But if she ain't stock, then a BOV might have been added. Anyway, the top metal line to the WG does indeed just vent to atmosphere, unless there's an adjustable boost controller installed.
My wastegate vents the exhaust though the left hand side "fake" tailpipe (matches the single exhaust exit of my muffler on the right side). One must always strive for the glorious WG opening sound....why muffle it (took my WG muffler off years ago).

[JFairman]

Nice car.
Sometimes the boost recirculation valve is referred to as a diverter valve. It gets called different things.
Hard to say what your HP is... Can't see what headers are on there but the turbo looks like a hybrid K27 7200.
With 964 cams it's probably around 440HP with good torque from the 3.5 liters and dual plugs if it has good headers and straight through free flow muffler.

The innovate LM-1 was discontinued a long time ago and is inconsistant junk by todays standards. I've never heard anything good about the LM-2 that replaced it either.
The best AFR gauge innovate makes is the digital MTX-L with a tiny self contained controller inside the gauge body. It comes with easy to change black and white faceplates.
I've had one for 2 or 3 years now and it always works great. I had an innovate LC-1 before it and it was a total piece of s...

Best price I've seen on the MTX-L is through amazon. Amazon.com: Innovate Motorsports 3845 MTX-L All-In-One Air/Fuel Ratio Gauge Kit for Powersports: Automotive
There's other good ones out there too.

[Tippy]

Ditto JF on the MTX-L

[THECARREAPER]

Many thank yous to all of you. I had 2 Lotus Esprit SE's with the turbo and the "Charge Cooler's ", but i really have a tremendous amount to learn about 930's, especially modded ones. I will order the recommended A/F ratio meter this weekend.

I dont know who makes the exhaust, but i have some crappy pics. Car sounds PISSED OFF and loud for a "911" but i have never had a 930 before.

Am I correct in assuming the exhaust has to come off the car to drill and weld the bung for the sensor?

Surely I don't want get metal shavings from the drilling into the exhaust and damage the turbo ? Correct?

Thank you. I am sure i will have more New Guy questions soon.

[Norm K]

Originally Posted by mark houghton

Uh, Norm: Wouldn't you say that 'post turbo' and 'pre muffler' are the same things? Just pulling your leg

I would, Mark, except that I'm not always the proverbial sharpest tool ...

[Norm K]

Originally Posted by THECARREAPER

Am I correct in assuming the exhaust has to come off the car to drill and weld the bung for the sensor?

Surely I don't want get metal shavings from the drilling into the exhaust and damage the turbo ? Correct?

Yes, the muffler must come off. But once you give yourself adequate access (e.g. simple removal of the rear valance/heat shield and, perhaps, the easier-than-you-might-think removal of the rear bumper) getting the muffler off and back on could hardly be more straightforward.

and

Since you'll be drilling into the muffler tubing - whether you select the inlet as I did, or somewhere further downstream as Mark did, all the air/exhaust gasses will be moving away from the turbo, effectively mitigating the risk of any drill shavings or weld slag getting into your turbo. Still, catching as much of it as possible is always advised.

[IMR-Merlin]

I had varying results using Innovative products. On my current build I am looking for something different.

I ran the LC-1 on a Dinan M3 that I built and it was real buggy. Hope they changed/corrected their issues.

[gumba]

I wonder if it's the Innovate gauge rather than the LM-1. I run the LM-1 in the turbo and the VW bus using their G5 gauge. The gauge fluctuates a lot while driving. I've tried to dial down the response time. I've been running 2 LM-1's in our n/a race car using a dual a/f gauge built by Westach for the past 5-6 yrs. with no fluctuation or issues.
The 02 sensor is installed at the right end of the muffler where the egr valve line use to connect. The DP muffler is essentially an empty can.

[aseem]

Take a look at Zeitronix as well for a wideband. Their Zt-2 package with LCD is a great product which I have installed in my car. They have some nice options as well.
Zeitronix Zt-2 : SEMA Award Winning Wideband Engine Datalogging System

[IMR-Merlin]

Originally Posted by gumba

I wonder if it's the Innovate gauge rather than the LM-1. I run the LM-1 in the turbo and the VW bus using their G5 gauge. The gauge fluctuates a lot while driving. I've tried to dial down the response time. I've been running 2 LM-1's in our n/a race car using a dual a/f gauge built by Westach for the past 5-6 yrs. with no fluctuation or issues.
The 02 sensor is installed at the right end of the muffler where the egr valve line use to connect. The DP muffler is essentially an empty can.

It was the actual control box that the wideband O2 sensor plugged into, not the LC-1 gauge. When it worked, it worked flawlessly, then it started to burn through O2 sensors, they upgraded the software to change the heating circuit and since tht happened, it never worked right again.

[Groovie Ghoulie]

I would love to know why people insist the sensor must be mounted post turbo. I see many OEM manufacturers mount them pre-turbo on many cars. Also: exhaust Gas is Exhaust Gas, why should after the turbo matter?

Also: "because we have always done it this way" is not a viable answer (this is the internet after all). I would like some legit technical sources to read up on. Varying opinions are everywhere these days.

[Ronnie's.930]

^^^ I know that one good reason to mount the O2 sensor after the turbo is that if some of the sensor breaks off, it won't pass through the compressor and turbine wheels on its way out of the exhaust. I've never read of a sensor breaking apart, however.

[JFairman]

Originally Posted by Groovie Ghoulie

I would love to know why people insist the sensor must be mounted post turbo. I see many OEM manufacturers mount them pre-turbo on many cars. Also: exhaust Gas is Exhaust Gas, why should after the turbo matter?

Also: "because we have always done it this way" is not a viable answer (this is the internet after all). I would like some legit technical sources to read up on. Varying opinions are everywhere these days.

Because wide band O2 sensors are thrown off by the high exhaust backpressure before the turbo and therefore give innacurate readings if mounter there. Narrow band O2 sensors are not affected by exhaust backpressure and thats why one is there from the factory for the lambda computer.

For example if your turbo is making around 15 psi boost pressure the exhaust backpressure before the turbo hot side turbine will be around 30psi.
It will be a little higher with an old design journal bearing 3K K27 7200, and a little lower with a newer much more efficiant ball bearing Garret.

If you don't believe it just call the innovate tech support 800 number and ask them.

[jsveb]

Originally Posted by JFairman

Best price I've seen on the MTX-L is through amazon. Amazon.com: Innovate Motorsports 3845 MTX-L All-In-One Air/Fuel Ratio Gauge Kit for Powersports: Automotive
There's other good ones out there too.

JF, is the harness with this kit long enough for a 911, or does it require an extension?

Also, is there an output for an ecu, to tap into the O2 signal?

Thanks.

[THECARREAPER]

Originally Posted by JFairman

Because wide band O2 sensors are thrown off by the high exhaust backpressure before the turbo and therefore give innacurate readings if mounter there. Narrow band O2 sensors are not affected by exhaust backpressure and thats why one is there from the factory for the lambda computer.

For example if your turbo is making around 15 psi boost pressure the exhaust backpressure before the turbo hot side turbine will be around 30psi.
It will be a little higher with an old design journal bearing 3K K27 7200, and a little lower with a newer much more efficiant ball bearing Garret.

If you don't believe it just call the innovate tech support 800 number and ask them.

Great post. Thank you.

[RarlyL8]

Call Innovate? The same folks that sell junk that works for about 5 minutes? I wouldn't give a nickel for their advice.
Yes as Jim stated pressure does affect AFR somewhat. You can compare the readings from multiple sites and see the small differences. We know the range where the engine runs best at idle so it's not hard to find the best baseline reading. OEM bung is before the turbo but does not need or use accurate boost readings. Tailpipe is decent boost reading but bad for idle and cruise. Best spot for all readings is a minimum of one foot before the tailpipe. If installing long term in the muffler neck a heat sink is suggested for sensor longevity. As previously stated, locating after the turbo also eleminates the rare chance of a cracked sensor going through your turbo. I've got one of those on the shelf and man is it ugly.

[mark houghton]

Jeeze Brian, such slammage for Innovate products. You must have had a bad experience (or more likely, know of a bunch of dudes that have). Mine's been working fine now for what....maybe 5 or 6 years...with the sensor mounted as close to the muffler as possible in the tail pipe. Pretty basic setup, with analog gauge. Maybe I'm one of the few lucky ones.