Understanding gauges for superchargers and why you need them

[Romer]

Bear with my education process. I think this is worthy of a separate thread for others to search on.

I am trying to select gauges and prioritize which ones I need first. I am looking for correction of my statements below. Remember, I'm an EE so try not to get to technical in your answers. Actually I am in mangement now so you might have to dummy it down.

Seems to me the boost tells you how the supercharger is working and that it allows you to see when it is adding more power.

Water temperature gauge allows you to see how your colling systems is doing. This to me is a must to start with and the first gauge to get (Opinions??) This will tell me when to back off or that I have a problem that needs immediate attention.

Intake Air Temp gauge allows me to see if the air getting to the supercharger is getting hot decreases performance. This would tell me I need to do something to cool the air to improve the performance

An EGT gauge will let you monitor the temp of the exhaust and let you know if it is getting too hot and there may be a problem with being to lean or detenation.

The fuel pressure gauge will let you know when the pump is not providing enough fuel. I am going with the Supra pump to alleviate this concern.

Any I missed?

So I am looking at this greddy infometer that has sevral of the above and more built in with monitoring capability. It does not have boost. Can I infer the Boost from the intake manifold pressure?

It monitors 25 channels like Speedometer, RPM, Water Temp, Ignition Timing, Injector Rate, Intake Air Temp, Fuel Temp, Air Flow Voltage, Intake Manifold Press, 02 Sensor Voltage, A/F, Battery Voltage, Throttle Position, WGV, ATF Temp, EGR Temp, Gear Position, 4WD Ratio, Exhaust Temp.

So back to priorities. I am guessing temperatures are more important to ensure I don't damage the vehicle and the boost is information on how and when it is working. Opinions

 

[airlaird]

Ken, You know, many of us have suggested things like guages etc.. . You don't really NEED these guages...if you did, TRD would have supplied them. You don't really NEED a Supra fuel pump...if you did TRD would have supplied it. You don't really NEED a boost guage....if you did TRD would have supplied them. These guages are cool to have and to monitor the system. After 45,000 miles on my 1st Gen TRD S/C, (actually the first in Texas to have one put on), I have none of these mods except the boost guage. My truck still runs great and pulls like an english school boy. So please don't get freaked out by our suggestions as a "must have". Many of us ..including myself tend to scare people off on mods. If you bought all of these things we suggested...you've added about $600.00 to the equation. All these additions are great ideas....Please don't be overwhelmed.
In my opinion, you should have a Valve body mod done....this is a $500.00 dollar addition! some folks have had this issue...some not. Take the wait and see approach.
Oh, and yes you can hook up the boost guage to the manifiold.
airlaird

 

[Romer]

Thanks airlaird. I know a few folks who don't have gauges yet and don't have any problems.

Just want to make sure I understand what they all are and what they do for you. I would think using the OBD Temp values would be better than adding one because it's what the computer uses.

Mu OBD II Reader doesn't show real time data and I was thinking about getting one that does. These Digital gauges that read right off the OBD ports are the same price and so that could augment my current code reader.

On the manifold, my question wasn't were to hook a boost gauge to, but can I use the OBD "Intake Manifold Pressure" to get the same info.

 

[SUMOTOY]

Guages 101

Ken:
20 years of guage installs and eval, hoping I can help here. I will speak to guages in general, then analog vs digital.

FUEL
First, forget fuel pressure as a priority. It's a reference guage at best. IOW, you use it to set fuel levels if you are changing injectors adjusting fuel pressure regulators, etc. After you are done doing that, you remove it. BTDT many times

BOOST
First guage to buy with SC or turbo. Boost guage. The bigger ones tend to be more accurate than the smaller ones. Water filled are much more accurate than non. Autometer pro comp 2 5/8 water filled is the most accurate I ever installed (in the altimeter location of my 4R turbo). My 4R turbo was sensitive to 14psi vs 14.5, and I could dial in the boost controller very accurately with it.

For either water or non water filled, for low boost applications, the most accurate one is a 0-15psi fuel pressure guage. That's what I used in my S/C pictured below. It's a 1.5in guage, and in a S/C app is a good and accurate way to make sure all is well under boost, or identifying when you are. What surprised me the most as a turbo guy, when I thought I was in boost, I wasn't, and when not, I had 6psi. The one I picture below is not a lighted guage, but I don't miss that. It also has a chrom bezel that adds some bling to the install.

BOOST VS BOOST + VACUUM
The only one I found to be good here is the VDO 30Hg>25psi Vision Series. All the low pressure ones (15psi) don't appear to have very good vacuum calibration. Not sure why. I certainly wouldn't run over a 15spi guage with a S/C application, or even a turbo application, if you are running under that. More isn't better here if you never see it. In fact, a 0-10 would be fine for the S/C, they just don't make therm.

EGT
Useful for a turbo install, reference guage for a SC. Again, assuming you to be getting enough fuel, the EGT is a setup and forget program with fuel. EGT's get high enough, you should pick that up some other way. On a turbo application this is a must do, because temps go past 1600 with turbos, not with SC's however.

WATER
A good guage to have, given the accuracy of the stocker, or even the RT mod stocker. A good water guage is very accurate, and can give you the exact operating conditions of your engine. I tend to put a mark for normal operation, so that a quick glance tells you if you are heading up. Once you start heading up, it happens quickly, btdt.

OIL TEMP/PRESSURE
You have an oil pressure guage in the truck. You are familiar with what's normal and what's not. I'd skip adding a more accurate one. Oil temp is good, and one I'd have instead of water myself. It gives the long term heat trends in the engine. And you do want to see an occasional 100C temp.

INTAKE AIR TEMPS
I like these if using a dual probe (one pre IC and one Post IC). I suppose for heat management, might be a nice reference, but when you are logging/testing/modding, you can get this off the OBDII port if memory serves.

ANALOG VS DIGITAL
Spa makes the absolute best guages I've ever worked with. Their digitals have hi/lo memory, settable 12v relay triggers, selectable nigh vision colors, and dual guages in 2 1/16 round shells that are the meow. Expect to pay dearly for them, but that's as close to one of those indy car dash monitors you are going to get.

For boost, get analog. Digital boost guages will make your eyes flutter, btdt. A needle sweep is much easier to track and trend than digits wheeling faster than your eye can follow. I have used some of the 3 second averaging digital guages, which are fine, but may miss some anomoly by averaging.

OBDII, Zetronics, etc.
The OBD interpreters are ok, and I use them extensively for tuning/testing/diagnostic. I can't imagine having all that all the time being advantageous over a given set of guages. What I do for trips in my wife's v8 quattro, put the OBDII Palm reader and cables in the glove box, in case I need it for something. Otherwise the dash guages provide all the information I'm really interested in for driving.

SCREEN ANALOG
I'll add that there are also several digital screens that show analog guages faces with needles. They look kinda cool I guess, but they definitely stutter from the feedback loop on them. I haven't seen a refresh rate on them that comes close enough to an anaolog guage to give it the advantage. That said, if you are scrolling through checking for diagnostics, they are great tools, and can verify that something is amiss. I tend to think they would be an addition or reference to an analog guage during diagnostics, but not a good standalone guage reading. Again, expecially in the SC application, the supercharger bypass valve really wings that guage from 0>max boost>0 quite quickly. A screen analog may or may not be up to that task in clarity or definition.

Ken below is the VDO 1.5in fuel pressure guage Summit Part 153002 installed where the emergency flasher switch was, and a close up of the face. It is chrome, but I believe it's also available in black with white letters. When I towed the camper in June, I installed a temp water guage, which I have since snipped the zip ties on, but the sensor is still in the head. Boost and Water would be my first two and only guages I would use, especially if you have OBDII for diagnostics.

HTH

Scott Justusson
QSHIPQ Performance Tuning
Chicago IL
FZJ80 Supercharged

 

[Romer]

Thanks, I didn't see the answer to my question

On the manifold, my question wasn't were to hook a boost gauge to, but can I use the OBD "Intake Manifold Pressure" to get the same info.


This is what I am looking at. Again, the data from the OBD port would seem to be more accurate than an add on Temp gauge for operation. You seem to disagree.

http://www.rallysportdirect.com/shop/newsdesk_info.php?newsdeskPath=9&newsdesk_id=6

 

[SUMOTOY]

Thanks, I didn't see the answer to my question

On the manifold, my question wasn't were to hook a boost gauge to, but can I use the OBD "Intake Manifold Pressure" to get the same info.


This is what I am looking at. Again, the data from the OBD port would seem to be more accurate than an add on Temp gauge for operation. You seem to disagree.

http://www.rallysportdirect.com/shop/newsdesk_info.php?newsdeskPath=9&newsdesk_id=6

Be careful Ken. "Only some parameters may be displayed" could mean very few, specifically, the ones you want you may not get. I'd get only the ones you need as aux guages, and get a palm OBDII reader for diagnostics. You only want all that information if into diagnostics, you don't need it all dancing around when you are trying to drive. Even in the race cars I build, KISS for the driver. Big oil and Big water temp lights, water and oil temp guages ( you can use the same guage for each with a switch btw, btdt), oil pressure, and boost. With OBDII the rest is available, but not a distraction.

SJ

Scott Justusson

 

[Romer]

Scott, I can set it up so only one or two are shown in a mock gauge form or digital bargraph. I don't see it as a distraction.

Do you not know the answer to my question?

 

[SUMOTOY]

Scott, I can set it up so only one or two are shown in a mock gauge form or digital bargraph. I don't see it as a distraction.

Ken, I encourage you to get the water and boost guage in analog. KISS. I've done a complete Spa guage install and found it to be distracting. I've done even the Zetronic setups, and find that boost should be analog.

Go bling by getting chrome ringed guages. The extra information you *need* are just vital engine monitoring of water and boost. Full blown OBDII interpreters are beyond bling. You have to think in terms of usefulness and function. I think Mr. T did a great job of designing very clear and non blinged information into the dash of the 80 (a big change from my 4R turbo with electronic dash). It's very german inspired, and needs no gizmotology added.

Just IME/O

SJ

 

[Romer]

Scott,
Don't know what year you have but mine has a Manifold Absolute Pressure sensor that can be monitored real time via the OBD port. I blieve you are incorrect here. I just checked the FSM.

KISS would be plugging straight into the OBD port and setting up the display with the two things I want to see, knowing I could see others. Usefulness and function are better with the OBD. I can monitor 1 or two things and switch the display if I want to see something else. I can log items as well.

I haven't decided to go this route, but I don't follow your logic.Or better yet, thats why the make vanilla and chocolate. You might be more distracted by the digital displays, but I would not.

 

[SUMOTOY]

Scott,
Don't know what year you have but mine has a Manifold Absolute Pressure sensor that can be monitored real time via the OBD port. I blieve you are incorrect here. I just checked the FSM.

That would certainly be a major step forward for Mr. T et. al. I certainly won't argue it, I'd be more interested in what it's doing to the tables and what it's calibration value is. MAP in a non forced induction truck seems overkill, but hey, Mr. T has been known...

Ok, if so, then we have a couple of issues to deal with. First, MAP sensors are rated in mbar (1000mbar = 1bar = 14.7psi). To get a reading off a MAP sensor for boost, you'd need a MAP sensor calibrated to read up to at least 1.5bar (1 bar = 0 vaccuum + .5bar boost pressure). If it's not calibrated that high, you will get a dead guage above 1 bar, btdt (IOW, every measure over 1 bar is 1 bar). I'd be interested to see if that was something anyone has tried on their force inducted truck OBDII reader. Anyone?

Then, what is the value of that reading. Usually those are read in MBar, or Kpa readings, which would only give you a trend, and tough to read Ken. Or, if the gizmo takes that value and converts it to boost pressure. Ken if you look in the FSM, does it give a range for that sensor (usually in Kpa)?

On the old audi turbos, the dash boost guage read in tenths of a bar with a 3second trail average. So anything over 1.0 bar was boost pressure. I'm used to dealing with that in turbo diagnostics and service. But in a supercharged truck, or even a track/street car, 0-x psi is still my preference.

Ken, you need to understand that in the SC boost comes on (and off - bypass) really fast, so you will have spinning numbers, or a jumping equalizer for your eyes. It's bling without much use, something that gives the edge to an anolog guage, since sweeping needles and their maximum sweep is pretty easy to follow.

No doubt in my mind, you'll understand if you try to make it complicated. My suggestion, before you spend you money on the bling, get the 20USD VDO from summit. Then watch that for a while, and think of how what you see on the analog guage, will look like in electronic form.

First, Ken, you need to have something to read. That would mean installing the SC first.



SJ

 

[Romer]

Thanks Scott for your input. The display can be set up as analog dials that look just like a real gauge.

Anyone else have any input?

 

[airlaird]

Ken, I installed my boost guage (the "skinny vacuum hose") to the "nipple" on top of the manifold. It was that simple. My guage shows 6PSI at full throttle.
airlaird

 

[Romer]

Thanks airlaird.

I am leaning towards a regular gauge for boost and the OBI thing for the temps as it gives me two (Coolent and intake)

 

[Romer]

Ken
FYI, I added my comments on screen analogs to my Guage 101 post (#4).

SJ

I see that. I have seen analog gauges at work and do not agree with your conclusion.

 

[SUMOTOY]

Map Sensor OBD II

Ken:
I found the following chart for toyota N/A map sensors (1 Bar MAP sensor), that I believe also applies to your truck. (.5-3.9v, 30Hg vacuum = .5v, 0vacuum = 3.9volts). I suspect that your OBDII reader won't register anything over 0 vacuum. IOW, on your OBD II digital screen analog guage will read all boost pressures as 0 vacuum. Dead guage.

It also means that the FTU presumes all manifold pressures above 3.0volts to be 0.

Since there doesn't appear to be any TRD issued MAP sensors, it indicates that at least the pressure transducer can take the extra whack of boost without messing up it's vacuum calibration.

You may want to confirm this before sinking that kind of Jake. Any OBDII supercharged trucks with diagnostics that can shed some light here?

Cheers

Scott Justusson
QSHIPQ Performance Tuning

 

[Big_Moose]

Ken,

The answer is yes, the OBDII scanner will read "Manifold Absolute Pressure", but, I don't think is would provide measurable information or the boost values you are expecting / need. If, I remember correctly, the later model 80's use a MAS sensor (similar to a MAF), while the early 80's utilize a MAP sensor.

The same applies to the Intake Air Temperature, but, I can't remember where the factory sensor is for this reading. Since the SC compresses the intake air charge, which creates additional heat, so theoretically the air charge temperature is greater than the intake air temperature (dependent upon sensor location), and would be a moot measureable point.

As you have mentioned, the two most important measurable parameters would be water temperature & boost / vacuum. I use the combination boost / vacuum gauge, which provides information on SC performance, engine performance, etc. My boost gauge reads 10psi under wide open throttle.

I really like that GReddy unit, and would use it to monitor water temp and tranny temp. Where are you going to mount this unit so you can easily read it in critical conditions?

Joe

Thanks Scott for your input. The display can be set up as analog dials that look just like a real gauge.

Anyone else have any input?

 

[619TOY]

For a very educational webpage on superchargers and gauges, etc. check out gadgetonline.com. This page is based on 3rd generation 4Runners but you will learn alot.

 

[Romer]

Joe, thanks for your input and the answers I was looking for.

If I get only a boost gauge then I think there is room on the pillar. If I get boost and Temp, then I will have to think about it.

One need I have is my OBD scanner does not show real time data. So it would be either get this or an OBD Scanner for the same price that displays similar data or look at one of the tailored PC/Pocket PC packages.

 

[SUMOTOY]

Ken,

The answer is yes, the OBDII scanner will read "Manifold Absolute Pressure", but, I don't think is would provide measurable information or the boost values you are expecting / need. If, I remember correctly, the later model 80's use a MAS sensor (similar to a MAF), while the early 80's utilize a MAP sensor.

I thought they all used MAF, the pre OBDII used a flapper style, OBDII used vortex or hot wire. The later 80 MAF also incorporates MAP, and from the graph above, most likely just for altitude compensation (needed for the later style MAF's). My 94 80 has no MAP sensor, because flapper style is a mass based unit, less dense air, flap won't open as far.

MAP sensor location is usually in the intake manifold (electronic sender) or it is a maniold hose to the MAP in the FTU, usually found on the german turbo cars. My research indicates that Mr. T uses a 1 Bar MAP sensor in non forced induction applications. This means there is no reading on boost applications, more specifically, it will read all values in excess of 0 vacuum as 0 vacuum. I believe however, if you can match the vacuum voltage on a 2bar sensor from a toyota turbo application, you could get readings on boost. I also suspect that OBDII will trigger a CEL with one, because it's getting a voltage on boost that's out of range. The best hope is that it would just ignore it, but most OBDII programming doesn't ignore out of range values without CEL. I also suspect this is an expensive option to just get OBDII MAP reading. It would certainly be a must if looking to tweek the SC programming ala the 4 runner SC TRD offering.

The same applies to the Intake Air Temperature, but, I can't remember where the factory sensor is for this reading. Since the SC compresses the intake air charge, which creates additional heat, so theoretically the air charge temperature is greater than the intake air temperature (dependent upon sensor location), and would be a moot measureable point.

From what I can tell, Mr. T uses two variants, 1 mounted in the airbox, the other integral to the MAF. So it will only give IAT pre supercharger, but it is not a moot measureable point. If you know pre compressor temps and pressure, and post compressor temps and pressure, you can calculate compressor efficiency. You can also directly see differences in ideal IAT (ambient) vs engine bay (radiant and forced/free convected) heated IAT. A good way to measure affects of heat management modifications on IAT.


Scott Justusson

 

[FirstToy]

Where are you going to mount this unit so you can easily read it in critical conditions?

Joe

That's a good point too. Don't know the dimensions but maybe replace the clock w/ that Greddy unit... I guess somewhere near the direct line of view is best but not much playroom...