1 bar = 29.92 inches mercury (Hg) or 14.7 psi. So one division is very close to .5 psi

If you ran .5 bar the gauge would read about 45.

Jim,

I am confused and I plead total ignorance, but completely fascinated and obsessed with learning. Why would the gauge read 45? Is there a multiplier? Or does the gauge show measurements in something other than inches (hg) or psi? What does "inches mercury absolute" mean?

What kind of readings would I get with this gauge on my NA motor?

FYI, from Wikipedia:

Conversion chart here: http://www.iprocessmart.com/techsmart/conversions.htm

I love Ebay!
 

Hey Jim,

I found these two on Ebay: First one is $180

http://forums.pelicanparts.com/uploa...1182885746.jpg

http://forums.pelicanparts.com/uploa...1182885827.jpg

This one only has one needle, but the price is right at $30.00

http://forums.pelicanparts.com/uploa...1182885911.jpg

http://forums.pelicanparts.com/uploa...1182885931.jpg

The term absolute means "absolute zero", as in no pressure - a complete vacuum containing no air molecules.

Notice that these gauges all read about 30". This is the pressure increase to go from absolute zero to atmospheric where the gauge was located when the picture was taken. Sea level pressure is 29.92 inches (one barometer) though this can vary a little due to weather conditions. If you run .5 bar boost this would equate to .5x29.92=14.96 Add the 14.96 to the existing reading on the gauge, hence ~45

Look back through this thread and you will see a picture of my gauge on a work bench, it indicates 26-27". This is the absolute atmopheric pressure where I live, at 3400 feet elevation. Note that this is 3"-4" less than at sea level (29.92) and equates to 1.5-2.0 psi less than sea level. I'd hit .5 bar boost here at about 41" (14.96+26=~41). Does this make sense? (I don't articlulate very well)

These gauges are a little more accurate due to aviation appication, and the dual input is great for mearsuing pressure loss. The gauge you found appears to have the guts of a single reading mechanism isstalled inside of a dual reading housing.

I got it! Thank you, Thank you! BIG smile here in Memphis...

Jim,

I watched the video again. Wow!

What two pressures are you measuring? I think one is connected to the throttle body for manifold pressure? Is the other connected to your IC?

What is that red light that blinks on?

If I am going to boost without an IC, would the gauge with only one needle be useful?

Jim, after looking at your webpage, with all of your fabrication on it....I only have one word.....INCREDIBLE!!!! I have allot fo respect for a person who can fab up his own stuff. The cage, the front suspension, WOW, very, very good job!!!! That front suspension is a work of art... very nice

You could measure before and after your throttle body if you had the double gauge. Would be interesting.

Hi Nathan,

I am going to hold out for a double gauge. It will not cost that much more than the single. I found one for $35.00 plus shipping.

Hi Jim,

Saw this thread on the SDS Fuel & Ignition system you used in your 930. I'm thinking of using this same system in my 3.2L Carrera (non turbo) and from your great thread I figured it looks much easier to upgrade a 3.2L Motronic to SDS. I have in mind the EM-4 6F system. One problem area that has me worried is the Crank Pos Sensor, could I use my existing one? or (most likely) will have to use the SDS one, if this is the case I really like how creative you got with placing it at the pully end of the crank. By any chance do you ever do work for others? like making this pully mod and mounting bracket?

At first glance it would be great if one could use the existing sensors from the Motronic (ie: Crank Pos, Cyl Temp, Air Intake Temp). Any thoughts on this?

Or is there a better system on the market for upgrading Motronic 3.2L that would allow one to use most of the stock sensors and setup?

Thanks for your time.

Sal, you may want to check out www.maxhpkit.com. A number of 944t guys on rennlist are using this motronic programmer and are apparently very happy with it. I don't have any experience myself with the product but found it doing some research. They say that they are beginning development in the coming month, but I'm not sure how long it takes to complete. It looks promising and would be cool to be able to keep the motronic.

And just to stay on topic, this is still my favorite pelican thread of all time...Thanks for sharing with us Jim:)

Mike, thanks for the link - sure seems like yet another option. Sure seems simple to install.

However, what got me started thinking about replacing the Motronic is that I wish to get rid of the Air Flow Meter (Barn Door device) These AFMs have always made me wonder what happens to the Motronic Data Maps as the AFM get old and the spring starts to sag. Also they seem very restrictive to air flow.

So while thinking about this I found SDS fuel and Ignition system and really like the idea of getting rid of the AFM and the distributor completely. However, would also like to keep as many of the stock sensors as possible - or - at least have new sensors that mount right in the stock locations.

With so many Carrera cars on the road these days I would have thought someone would offer such a kit. I think any EFI pro could come up with a solution that would just replace the Motronic system.

Thank you for the link to the Motronic enhancment, I have not ruled it out and will look some more at it.

No problem Sal, you could also look at a MAF conversion to replace the AFM. I just tuned a friend's e30 M3 with a DTM style airbox and MAF conversion. To be honest, not much extra hp (8hp) for the 2.2K conversion price on a stock M3, but obviously room to grow and the intake sound is pretty cool.

Sal,

Pat Williams in Memphis offers an EFI kit. Excellence magazine did an article about in 2005. From what I have read here on the forum, EFI is an expensive conversion that makes the most sense for Turbo applications where greater than 400hp is the goal. There was a thread last week about the expense and obstacles of installing and tuning EFI.

Good luck and start a thread if you decide to take on the challenge. I would like to follow your adventure.

Also, the AFM does not allow the use of radical cams. I would love to fit a wild cam in my 911 3.2 carrera but at the price for just a MAF it is a no no.

A plug in ECU is what we need.

Sal, it would be best that you call SDS directly as I'm unable to provide definitive answers to your questions. However, I think SDS said they can interface directly with the Carrera cyl head temp sender and air temp sender. Regarding the crank position sender I'm pretty certain you need to install the pick-up and magnets as I did.

I don't do any of this work on the side, but I do have a spare throttle position sender adapter as pictured early on in my thread.

Mike, thanks for the feedback, again!

Nathan,

Not sure how radical cams you are going for but my 3.2L has NON stock top end. I'm using WebCam 20/21 grind with my stock AFM and Motronic system. Car is a scream, has a custom chip from Steve Wong that was created from a Dyno run (run was done with stock chip). After the custom chip the HP was about 260HP at the crank.

Here's the run data before and after:
http://www.911chips.com/dyno.html
it's the 7th one down or search for '84 3.2 Carrera on a Dynojet 248c'

The WebCam 20/21 is not all that radical but is very nice addition for a street 3.2L

Jim,

send me PM with price on the TPS mounting plate.

And thanks for this great thread.

Thanks Sal.