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-   -   12-14 MPG for a 3.3L Turbo (http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/564323-12-14-mpg-3-3l-turbo.html)

Tilikum Turbo 09-14-2010 10:19 AM

12-14 MPG for a 3.3L Turbo
 
Is that about right for a 3.3L Turbo(1986 US version)?

RarlyL8 09-14-2010 10:28 AM

With a worn out WUR, yes. With an adjustable WUR 21-23mpg.

87 930 09-14-2010 10:39 AM

I'm running too fat and I get 16-17.

Richard930 09-14-2010 11:09 AM

Got 22+ mpg on my last long run thanks to high 14s AFR in cruise. Could probably do even better on the highway if I leaned it out a little more, but that would mess up my other AFRs.

Short trips around town on and off boost its a different story; 13 -14 mpg is normal.

Noah930 09-14-2010 12:18 PM

Quote:

Originally Posted by RarlyL8 (Post 5560291)
With a worn out WUR, yes. With an adjustable WUR 21-23mpg.

How can you say that without knowing his driving conditions/habits? Or are you saying that a properly tuned 930 should be getting over 20 mpg, regardless of the heaviness of the driver's right foot?

FWIW, I get that 14-16 mpg in mixed street driving, but about 20 mpg on the highway.

RarlyL8 09-14-2010 01:00 PM

4th gear 70mph steady cruise. Yes a properly tuned stock geared CIS 930 should get 21-23mpg on the highway and ~15mpg in town. Boost is not figured in as you don't do that if you want good mileage. These figures are good for power levels from stock to 400WHP. I don't have any data above that point.

Oheggem 09-14-2010 01:36 PM

If i converted miles to km and gallons to liters correctly i got about 8 MPG on a mixed 300km roudtrip this summer. About 2 liters on every 10 km.

It has a few mods though but i thought that was not very good. Costs to have a smile on my face. :D

WPOZZZ 09-14-2010 02:15 PM

Damn, I'm getting 11-12.

mark houghton 09-14-2010 02:27 PM

I get 20-something just mellow cruising (not boosting). For those of you that are sucking big wind in that regard, well....you're just running a lot richer than you need to be. 14.0-14.2 AFR at cruise/14.4'ish at idle is where I've settled at (I used to run stoichiometric 14.7, but found she runs better a bit richer than that).

e170drvr 09-15-2010 07:57 AM

Mark, you are running open loop? I'm still trying to find the sweet spot, I've got my idle at 13.9 now. Cruise are around 14.0ish, On boost is well...rich. I have no idea what the mpg is! Can't keep my foot out of the boost since I installed Brian's headers!!!

RarlyL8 09-15-2010 08:10 AM

Mid 13's at idle is fine as that translates to ~3% CO. Cruise is where you pick up the mileage of course and mid-14's seem to work best. Boost is like 5-6 mpg in the high 11's:1 so that is probably what you are getting! I find myself driving the car at higher RPM's to hear that tuned song, really sounds cool.

Schwarzeritter 09-15-2010 08:22 AM

I think it depends on the parameters, individual cars, modifications, enviormental conditions that be, amongest other things. Tuning as well.

So is the issue that you want better fuel econ?

Tilikum Turbo 09-15-2010 02:04 PM

Quote:

Originally Posted by Schwarzeritter (Post 5562215)
I think it depends on the parameters, individual cars, modifications, enviormental conditions that be, amongest other things. Tuning as well.

So is the issue that you want better fuel econ?

The real issue is waste...even if someone gave me a 50,000 gallon rig in my backyard for free with 100 octane fuel, I still would be concerned with MPG. Engineers can never leave well enough alone when it comes to efficiency.

My car is also completely gutted of all A/C stuff from stern to stern, rear seats, spare tire, radio/electric antenna, and soon to go will be the fog-lights(which basically are useless in a semi-desert), and some lightweight seats.

I'll keep at it!
:D

Miguel Antonett 09-15-2010 02:19 PM

What about some pictures of the car?

Tilikum Turbo 09-15-2010 08:39 PM

Quote:

Originally Posted by Miguel Antonett (Post 5562982)
What about some pictures of the car?

http://forums.pelicanparts.com/uploa...1284611869.jpg
http://forums.pelicanparts.com/uploa...1284611930.jpg


Here's a few...

930cabman 09-16-2010 08:56 AM

10 mpg
 
My 1987 turbocab with 84k miles appears basically stock with the exception of a 1 bar spring and a RUF muffler and generally get about 10 mpg average around town with somewhat of a lead foot. Thanks for the tip regarding the WUR. I do need to purchase a decent air/fuel gauge, any ideas?

thanks,
John G

mark houghton 09-16-2010 09:15 AM

Quote:

Originally Posted by e170drvr (Post 5562146)
Mark, you are running open loop? I'm still trying to find the sweet spot, I've got my idle at 13.9 now. Cruise are around 14.0ish, On boost is well...rich. I have no idea what the mpg is! Can't keep my foot out of the boost since I installed Brian's headers!!!

Yep, open loop. One of the first things I did was to unplug the O2 sensor and tune the engine around it.

Tilikum Turbo 09-16-2010 11:55 AM

Quote:

Originally Posted by 930cabman (Post 5564470)
My 1987 turbocab with 84k miles appears basically stock with the exception of a 1 bar spring and a RUF muffler and generally get about 10 mpg average around town with somewhat of a lead foot. Thanks for the tip regarding the WUR. I do need to purchase a decent air/fuel gauge, any ideas?

thanks,
John G

Holy cripes...and I thought I was getting low MPG!

That RUF muffler...is that with or without a CAT?

And is it signficantly louder than stock?

911st 09-18-2010 07:29 AM

I suspect the best opportunity for improvement is not on the fuel side!

However, a good working lambda system with the AFR's / CO adjusted to a working range that the lambda can adjust around should keep the AFR's near 14.7 at cruse which would be a good place to start in search of better MPG.

To improve on this look to the ignition for the best gain in MPG!

Most US 911's do not have anywhere enough timing advance at cruse. Usually it is something like 25 deg total advance by about 2500 to 3000rpm. In many cases we are not even going to see our total advance on the freeway at legal cruse speed to run efficiently.

Get total advance to around 33 deg at lite cruse and there will be a measurable improvement. The motor should also run cooler.

A low restriction exhaust for less pumping loss and stock light weight wheels with the right tires for lower rolling resistance can also help.

http://forums.pelicanparts.com/uploa...1284823654.gif

RarlyL8 09-18-2010 09:09 AM

EFI 930's with engine management control of ignition typically don't do much better than low to mid 20's mpg from what I have seen. I think Don gets 28mpg with his which is exceptional. That is off-topic though as stock equipment is CIS with a distributor.
There are gains to be made on the ignition side but it is diminishing returns after you repair or replace the rich worn out WUR's that are on a lot of cars. Going from low to mid-teens to low 20's mpg is pretty huge for just replacing one component.


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