MG Performance Forum

I have started looking at air / fuel gauges to go along with my SC installation. There appears to be numerous choices to make. What would the forum members suggest as to make, model, options etc.? Being electronics impaired, I am almost clueless as to the best selection.

Lonnie

Hi ,
Regardless of the gauge .. take care of the sensor .

The “ old” UEGO 4.2 LSU does degenerate over time .
The “new” UEGO 4.9 LSU does have calibration build in. A kind of a lifetime calibration.


My first AFR measurement in my MGA I did with my AEM failsafe gauge . ( PN 30-4900)

The gauge combined AFR reading , manifold pressure reading , RPM reading and data logging in 1 device.
With some logic to switch for example a warning licht when crossing software adjustable AFR-Boost limits.

Pretty good and convenient… especially the “in the gauge” data logging .

The downturns are :
1) based on a Bosch UEGO 4.2 LSU sensor
2) pressure sensor a bit of and no possibility to calibrate on this
3) hard to get a RPM signal into the unit correctly
4) AEM software not evolving ; a feeling of neglect of the AEM FSB .
5) most important … not available anymore .

In 2016 a new AEM FSB was released .. the PN 30-4910. With the possibility to combine with a flex fuel sensor.
This gauge is also no longer available .

So yes .. it did and does his job of seeing AFR / pressure / RPM and logging data sets .
And it gave my a tremendous insight in the function of the SU carb and the combined accuracy and repeatability of the SU.

I hope AEM will come up with a successor . Based on a LSU 4.9 and a more robust software environment .

Otherwise I would consider to go to an innovative Motorsport PSB-1 .. the pain would be the not build in data logging.

Hopes it helped in your search .

Seph

Seph, Thank you for your detailed reply. Unfortunately, I don't understand most of your details. That's a problem on my part, not what you offered. The Innovated Motor sport PSB-1 you pointed out at the end of your post is pricier that I was planning on. Basically, all I want to know ( I think ) is the A/F ratio to allow proper tuning. This car is a pleasure car for the street. I have no plan to go racing with it. All I'm after is a bit more umph in my "77B. Basically I don't know enough about the subject to make an informed decision. especially for $300.00. Is there a reasonable option in the under $200.00 range that might fill my need? If not, I will probably purchase the PSB-1. In addition to A/FR it appears to be able to show vacuum and boost which as well would eliminate the need for a boost gauge.

Lonnie

Not for everyone but I actually prefer the Innovate LM-2 handheld to the permanently installed ones. No need to weld bung into exhaust and can be used on multiple vehicles. I just make a simple sample probe out of cheap copper tube to suit each vehicle, install it, tune and then remove it.

Here is a pic of a couple of probes I have made, one for cars and one for motorcycles. The longer the probe, the more accurate the readings, especially at low load conditions.

Doug

Lonnie ,

I think Doug makes a good point in your context .

Adjusting a carb with a “static” AFR device is for a lot of cars enough.

Seph

I also use the Innovate LM-2.
It’s a good tool and I prefer to datalog when tuning. A little searching should turn one up for about $225.
Unless you just want to see it while cruising I don’t find a lot of value in watching AFR or boost if you are making 5psi after properly tuned.
I do like to know MAP (boost) vs AFR when tuning.
I don’t think your supercharger has a bypass so maybe that isn’t critical once you know your max boost.

If I wanted to look at a gauge and datalog, I would buy the PSB-1.
If I wanted to watch AFR I think any $200 gauge kit from Innovate or AEM would work fine and I would just pick one where I liked the look.

This is what I have in the race car, I have both AFR and twin needle EGTs. It has worked flawlessly for well over a decade, and the O2 sensor has stood the test of time, as many don't with leaded race fuel.If I had to pick witha twin SU carb set-up, which is not the case for the OP, I choose the twin needle EGTs as they let me get a read on each carb. On a single carb, o FI setup, I would go with AFR with a O2 sensor.

https://www.autometer.com/2-1-16-wideband-a-f-street-ultra-lite.html

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 1 time(s). Last edit at 2024-04-17 07:32 AM by Speedracer.

I have used two Innovate units and they are real good units though some other brands may be better? I would not buy one with the older 4.2 sensor, go with the 4.9 sensor as the old ones can't read very far into the rich side and may not last as long.

As Hap noted don't put these on a cart that will see leaded fuel. If you run it with leaded gas it will wreak the sensor and if purge the tank and run unleaded the lead remaining in the engine will likely take out the second sensor too.

You can log things better by looking out the window and driving while a cell phone records the gauge. Drag a in a vacuum gauge into the picture and you'll be able to compare it to your throttle.

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Ken Adkison
Hoping we all get the best running car we can, out driving, so youth see and dream of curating our efforts forward another generation

1975 MGB restored in 2009 to near stock with 9.8:1 compression and mild cam .

Developed Modern Engine Management System
Bespoke closed loop, sequential, port fuel injection system based around MegaSquirt MS3-Pro controller.
Hand made intake, wiring and other parts.

https://www.youtube.com/channel/UCcdmkAGSliRgRzpdyuSaMrA

I've used Innovate, AEM and Autometer and I prefer the Autometer.

Jim

I’ve run the auto meter wideband for about 4 years now. I’m happy with it. It helps me tune and was easy to install since I had the bung already in my MOSS exhaust.

Brad

That is the same one I have, yes it has been dead nuts reliable, even with unleaded race fuel.

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

Hi Hap, can you explain how you would use the EGT guage in place of an AFR one with twin SUs? Thanks!



Edited 1 time(s). Last edit at 2024-04-23 09:42 PM by dylan873.

I uue both, the EGTs probes are 6" from the header measured from the header flange to the head downward, one goes on the front header tube (for front carb), one on the black header tube (rear carb), Since I run twin HS6, a AFR gauge alone can not show me what each carb is doing, The EGT let me look at front vs rear carb, many times we will find, one carb needs a different jet height setting that the other carb to acheive the same exact readings. The AFR gauge is back up set-up, it only shows an overall look at both carbs and it's probe is just past the header collectors as shown above. On the race car I am looking for 1300 degrees on both carbs at WOT on the longest straight in top gear, and that normally nets me about 12.5 on AFR.

ON my set-up with twin carbs, give me a choice between the two, and I pick the EGTs every time due it's ability to read both carbs independently, however, if one only has one carb is suded, then a AFR alone should do the trick.

Here is the EGT gauge I use and the probe type.

Guage type : Dual needle : https://www.westach.com/product-page/2da2-47

Probe type, band clmp style, require a 3/16: hole in header tube for the probe. https://www.westach.com/product-page/712-2dwk

Also worth noting an EGT is a thermocouple type gauge, like early MGB's mechanical water temp gauge meaning it is mechanical, not electrical, since we race in the day, I have no need for light in my gauge, for use in the dark they sell a separate light kit for the gauges.

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 2 time(s). Last edit at 2024-04-24 07:16 AM by Speedracer.