EGT vs. wideband O2 gauges

[hsk8te2006]

Hi Everyone,

I need help making a decision.

Right now my '96 GS-T is essentially stock and I'm adding gauges first. I'm not planning on upgrading the turbo (budget conciencious), but I am planning on cheaper mods like cone air filter, UIC pipe with 1G BOV, high-flow Cat-con, wastegate restrictor removal, and perhaps a manual boost controller. Down the road I may get a full turbo back exhaust, but no plans yet. I'm looking to keep the future in mind in case I do choose to upgrade further, so I'm looking for experienced opinions.

I'm already planning on electrical boost with peak. I've been told that EGT can be handy. However, I've also read that a wideband O2 sensor may do more good than an EGT. Opinions please?

Also, I can use second opinons for my third A-pillar gauge... I'll have a good sense of what's happening inside the engine with an EGT or wideband O2, and the stock coolant temp gauge is accurate enough to let me know if there's a serious coolant system problem. I figure an oil temp gauge or fuel pressure gauge won't be much use on a nearly stock car if I have an EGT or wideband O2. That leaves me with voltmeter or oil pressure, and I figure I'd rather run out of electricity and need to be jumped or towed before trusting the non-reliable stock oil pressure gauge to alert me before my engine siezes if there's a drop in oil pressure due to a problem, so an oil pressure gauge with peak and warn may be best. Does anyone disagree with this logic?

Thank you so much,

Hsk8te2006

 

[Talesin]

An EGT is cheaper than a WBO2. If you have a WBO2, an EGT gauge is pointless. Both are only really useful if you're tuning your car, such as with DSMLink or an SAFC.
EGT is there to give a rough guesstimate if you're running too lean or rich, by looking at the output temperatures. If it gets too hot, likely too lean unless you're washing the cylinders with fuel in your tuning solution.
With a WBO2, you can see exactly how lean or rich you're running. With a good mixture, you won't run hot, so there's no need to have an EGT.

Oil pressure or temp would probably be best... I'd go with the temp myself. You have two stock sensors (in-dash pressure gauge and the idiot light, which uses a seperate sensor) for pressure, but nothing to tell you if the oil is getting too hot. And the stock oil pressure gauges *are* reliable... they just aren't calibrated to any set psi point. If you see that needle drop, you're losing pressure. The only thing an aftermarket pressure gauge is going to tell you is how much it dropped, exactly. Which you don't exactly care about if it's falling fast while you're boosting, just that it's falling.

There's also NO reason to run a peak-and-hold oil pressure/temp gauge. It's pretty pointless. I'd say the same about the boost gauge though... a standard mechanical is all you really need, even if having a warn light/buzzer could be handy to alert you to an overboost condition. But that's about the only reason to get one.

 

[hsk8te2006]

What benefit is there to knowing the oil temp? I would figure a low oil pressure warning light or beep could be a good insurance, no?

I was thinking of a peak boost gauge so I can track if my mods are helping or not, plus I have parts for 2 UIC pipe/filter combinations right now (must test together because one filter is too big for combination with one of the UIC pipes), and I figure a peak boost measurement from a consistant full second gear hard run should be useful to determine which pairing works best.

 

[Talesin]

If the oil starts to overheat, it loses viscosity and (more importantly) shear strength.. gets thin. When it gets too hot, it can get dangerously thin, leading to spun bearings, scored rotating parts, and other unpleasantness. It's VERY useful to know how hot your oil is getting, especially if you drive hard or autocross for extended periods. You already have a low oil pressure warning light in your dash cluster. It's the oil 'idiot light'.

You aren't going to get more boost off a different UICP or intake. That's pure wastegate actuation, and it'll always open at the same point, aside from boost creep or spike, both of which are BAD things. Both of which are easy to see if you just watch the gauge... having a peak level is pointless, unless you're doing serious high boost application and can't look at the gauge while you're trying to keep the car going straight.
Pipe is pipe. For intake tract, 2.5" should be more than enough for most everyone, until you're trying to make 700+whp, at which point you'll probably know just what size you'll need.
The only difference an UICP or intake will make is how fast the boost comes up... which a peak gauge will NOT record.. so it's kinda useless for that, too. :b
I really wouldn't stress over which to use. Go with whichever fits, has the least bends possible, and the smoothest bend radii possible. You aren't going to gain or lose THAT much between two different hardpipes, especially compared to the stock flex piping.

 

[thekellbeast]

Also, don't turn up the boost until you have some sort of logger. You could use a pocket logger/Palm 'n' stein/whatever they have these days. I just got DSMLink and I'm trying to track down a laptop with a serial that I can run it on.

Back on point, don't start turning up until you have a way of knowing what's going on inside the engine.

 

[bling5tatus]

Ok, what are good oil temp numbers, and what would be too much? Should it be ~ the same as the coolant temp? I would think they should be close to the same. What would cause the oil temp to be higher than the coolant? Like, say, why can't I just keep an eye on my coolant temp and have a good idea of how hot the oil is? I mean obviously, it's the coolant temp and not oil, but other than that, are they not very similar or what? Please elaborate, and thanks in advance.

 

[hsk8te2006]

Thank you so much for the advice on the pipes. I appreciate the effort you're putting into helping me figure my new car out.

When you say that the amount of boost is pure wastegate action, are you saying that a stock 2g will be boosting up to the stock wastegate's limit already? What is the stock 2g wastegate limit?

I'm not looking to turn the boost way up.... maybe a few pounds... for example, I read that removing the restrictor in the wastegate actuater will tend to raise the boost between 1 and 2 psi, and I also heard that this is generally safe for a stock car.

Speaking of which, for when i get a boost controller, any ideas how high the boost can safely go on a 2g turbo car with a stock fuel system, stock timing and ecu, stock IC and nearly stock intake? Is the EGT a reasonable sign to watch in my case?

Also... you say not to turn the boost up without knowing what's going on inside an engine... is the EGT not enough info for a low boost increase on a stock car? ... A datalogger isn't recommended by the tech pages until a "stage 2 setup of over 300 hp.

Thanks for your input guys.

 

[donmagicjuan]

For the record, the stock temperature meter is not as reliable as you might think. Slap on a ginormous FMIC, hack your bumper cover to hell, and log your coolant temperature while you go for a nice spin. You'd be surprised how high the actual temperature gets (to the point of pulling timing) while your stock meter just sits fat, dumb, and happy in the middle of its band. I'm not preaching that you should run out and buy an aftermarket coolant temperature meter (I don't have one), but be careful how much faith you put in the crap stock one.

Oh, and I vote WBO2 over EGT.

 

[kenamond]

Thank you so much for the advice on the pipes. I appreciate the effort you're putting into helping me figure my new car out.

When you say that the amount of boost is pure wastegate action, are you saying that a stock 2g will be boosting up to the stock wastegate's limit already? What is the stock 2g wastegate limit?

I'm not looking to turn the boost way up.... maybe a few pounds... for example, I read that removing the restrictor in the wastegate actuater will tend to raise the boost between 1 and 2 psi, and I also heard that this is generally safe for a stock car.

Speaking of which, for when i get a boost controller, any ideas how high the boost can safely go on a 2g turbo car with a stock fuel system, stock timing and ecu, stock IC and nearly stock intake? Is the EGT a reasonable sign to watch in my case?

Also... you say not to turn the boost up without knowing what's going on inside an engine... is the EGT not enough info for a low boost increase on a stock car? ... A datalogger isn't recommended by the tech pages until a "stage 2 setup of over 300 hp.

Thanks for your input guys.

The stock 2g wastegate actuator (WGA) opens at about 8psi. The stock BCS bleeds off some of the boost so that the WGA sees less of the actual boost pressure. The statement "pure wastegate action" requires a bit more explanation. The compressor is a centrifugal pump that forces higher-pressure air into the motor, and the ECU adds the right amount of fuel to that air (if all is going well), so you get more power. The exhaust from the motor drives the turbine which drives that compressor (they're on opposite ends of the same shaft). The wastegate is a hole in the turbine housing that is blocked by a valve. If the valve is opened, exhaust bypasses the turbine wheel, the turbine wheel has less torque applied to it, it stops accelerating, the compressor stops accelerating along with it, and the compressor outlet pressure (boost) stops increasing. If the valve is closed, all exhaust gas goes through the turbine, increasing amounts of torque are applied to it, it accelerates, the attached compressor accelerates with it, and boost continues to go up. The wastegate actuator is connected to the valve in the wastegate and controls when it opens. This has nothing to do with intake pipes, upper intercooler pipes, BOVs (if they'll hold the boost), etc. So changing any of those won't affect boost, as this is controlled directly by the boost control system (which includes the BCS+ECU, WGA, and WG). The BCS restricter mod will increase boost, because you're now tinkering with the boost control system by increasing the amount of boost signal pressure (from the compressor outlet) that is bled away from the system before it gets to the WGA (so the WGA "sees" less of the actual boost pressure and opens the wastegate at a higher boost as a result).

Stock boost is around 11-12psi. Folks say you can bump that up safely to 15psi, but NOT WITHOUT A LOGGER. All cars are different, and a logger will tell you if you're having problems or not.

If you're sticking with the stock T25, I'd reconsider the 3-gauge pod. You only need a boost gauge and a logger. The WBO2 sensors cost $200+ depending on the brand and feature set. That money can instead go to a major go-fast part instead. And a $60 Autometer mechanical boost gauge will do just fine, though it's not as sexy as the $200, feature-loaded alternatives (more go-fast part money). If you intend on upgrading way beyond a stock T25, consider getting the 3-gauge pod and leaving 2 spots empty if you can tolerate the eye-sore. Or mount the boost gauge more simply and get the A-pillar pod later when you need it.

EDIT: But I should mention that you need to upgrade the 2g BOV to go much higher in boost, and intercooler pipes, aftermarket air filters, intake pipes, and exhaust WILL help with power. They let air flow more easily through the motor which increases performance. But they won't change boost.

 

[Talesin]

Sorry, I'd meant that the boost level wasn't dictated by how free-flowing the intake tract is, it's controlled by the wastegate, not an intake bottleneck of any kind. So swapping your intake pipe or intercooler piping will not raise boost, but it WILL result in smoother intake flow, increasing throttle response and overall power.

The OEM internal wastegate on a stock MHI turbo tends to open at around 10psi from what I've seen, with a line directly from the compressor outlet elbow to the wastegate actuator. A boost controller (the BCS is essentially a bleeder-type boost controller, feeding the bled-off waste air back into the intake tract) reduces the amount of boost that the wastegate 'sees', allowing it to stay shut longer, thereby building more boost before it hits the required pressure level to open. The BCS stops shunting (giving full boost reference to the wastegate) if the ECU detects too much knock, thereby dropping boost.. but it can't go below the wastegate spring pressure.

Far as I know, stock boost on a 1G is 12psi with the stock vac line setup, and the BCS in the loop, or 10psi when it sees knock. 2Gs supposedly boost at 14-15psi (roughly 14.7psi, 1BAR) and can be dropped down to that same 10psi when the BCS is tripped.



A WBO2 is a better solution compared to an EGT, if you're looking to actually tune the car. The EGT is more of a clumsy kind of band-aid that's cheaper, so a good number more tend to run it and just get a 'rough tune' based on their logger results, and a read from the EGT to watch for any temperature spikes which generally would suggest running overly-lean in a certain band, allowing the user to richen up that point.
If you're not looking to actually tune, EGT and WBO2 are pretty pointless to have, unless you just want yet another gauge to show off.

 

[hsk8te2006]

When you refer to "tuning", what is required to do that?

Also, if I don't invest in whatever is required to tune, do you think it is safe to increase boost by the 1 or 2 psi the WG restrictor removal will do without a datalogger or tuning equipment?

I've already received the 3-gauge pod... With only a boost gauge (that can warn in case of spike or creep), and an EGT, do you think it is safe to use a manual boost controller to increase by anotehr 1 or 2 psi beyond the wastgate restrictor removal?

THanks again

 

[Talesin]

Either an SAFC, DSMLink (and a '95 EPROM ECU to put it in), or the AEM EMS standalone replacement. SAFC is the cheapest. I really do not think you even need the EGT for the BCS restrictor removal mod.. just the boost gauge, for general safety. Unless you're tuning, the EGT is just yet another gauge. You'd do a LOT better to invest in a datalogger cable instead.

 

[bling5tatus]

yep, you need a logger... also, look into getting an innovate lc-1. It doesn't have a pretty gauge, although one can be hooked up... but it will provide the functionality of a wbo2 sensor to tune with (in combination with a logger).... so really, get a logger and a cheap wideband... you'll be good to go. Also, you'll want an afpr if you put larger injectors/pump in your car as the stock fpr will cause you to run rich as crap and make it difficult if not impossible to tune.

 

[Calan]

Logger first (mmcd or pocketlogger + palm IIIc is fine)

Like bling said... get a decent WBO2 without the expensive gauge. I have a Zeitronix ZT-2 unit that I'm very happy with. (It will also allow you to log using a laptop, but I mostly just use the palm).

The nice thing about the ZT-2 is that you can use the EGR input at the ECU to monitor your AFR on your logger, if you aren't in California.

The other guys made some good points also. The stock temp gauge is practically useless...but again the logger will show you the coolant temps. The stock oil pressure gauge is close enough to show trouble, but there is no way to monitor oil temp, so that would probably be my next choice for a gauge.. (In fact it is my next choice when I can afford a good one ).

So my picks... Boost/Vac gauge, a good logger, WBO2 unit (without the gauge for now), and Oil Temp gauge.

 

[bling5tatus]

so what was a "safe" oil temp? I'm thinking of getting a prosport oil temp gauge from prosportgauges.com... I still do not know what safe oil temps are though.

 

[kenamond]

When you refer to "tuning", what is required to do that?

Also, if I don't invest in whatever is required to tune, do you think it is safe to increase boost by the 1 or 2 psi the WG restrictor removal will do without a datalogger or tuning equipment?

I've already received the 3-gauge pod... With only a boost gauge (that can warn in case of spike or creep), and an EGT, do you think it is safe to use a manual boost controller to increase by anotehr 1 or 2 psi beyond the wastgate restrictor removal?

THanks again

If you have a logger, you should be able to do the BCS mod or even get an MBC and 2g BOV and see if you can push it up more. The logger will tell you if there are problems, and you can lower boost if you see problems. The tuning would come into play if you want to run higher boost but are seeing issues via your logger. Some things you'd have to do, though, may require additional parts. Like if you're leaning out when you raise boost, you might rewire your stock fuel pump and maybe go to a 255/AFPR. There's just not really a way to tune with the stock ECU.

To tune, you need either a piggyback like SAFC or DSMlink+EPROM ECU or an aftermarket ECU. Otherwise, you're at the mercy of the stock ECU settings.

The basic idea is to get as much power safely out of your engine. You do this by adjusting boost, timing, and/or fuel.

If you put larger injectors on, the ECU doesn't know that. If you do nothing, the ECU opens them up for the same durations it would for the smaller stock injectors, so too much fuel is injected, you run rich, and you lose power. SAFC is one way to handle this. It intercepts the MAS signal and alters it so that the ECU thinks it's getting less air than it really is, so it injects less fuel. You adjust this at different RPM ranges until you get things where you want them.

Knock is something to avoid. Things are getting too hot in the combustion chamber, and the fuel/air is burning prematurely. Typically, when you tune, you look for knock. You can retard timing if you have something like DSMlink, but you can't adjust the timing maps in the ECU with SAFC. In that case, you need to cool things down either by larger intercooler, water/meth injection, richer mixture, or lower boost.

You want to advance timing pretty much as far as possible without knock (there's a sweet spot that you don't want to go past, but if you can't reach that, you go as close as you can). Again, you do this in DSMlink or an aftermarket ECU. The timing advance depends predominantly on RPM and mass airflow. The timing map stores the timing advance as a function of rpm and mass airflow (3D data). So you'd be tinkering with this map if you were tuning your timing.

You also want an AFR in a specific range that is leaner than the stock setup. The WBO2 lets you accurately measure the AFR. Fuel maps can be altered in DSMlink etc., and the SAFC settings can adjust this by fine-tuning the "lie" about airflow to the ECU. Again, this is a map in terms of RPM and airflow (3D data again).

All of these things are interdependent.

That's a pretty crude description, but hopefully, you get an idea.

 

[hsk8te2006]

Man you guys are great... thanks for the info already.

so, next question... what logger would you reccommend for a car with a goal of squeezing as much as possible out of a nearly stock car (running the stock turbo for sure)?

 

[Calan]

DSMLink is pretty much at the top, if you've got an eprom ECU and/or the cash to get set up with the software (except for very serious/expensive standalone systems)... otherwise any decent and inexpensive (read outdated but fully functional) Palm Pilot with Pocketlogger software and cable will do just fine.

As I've stated many times, I love the Palm IIIc... it's got a bright color display, has a built in rechargable battery which is easily modified to always be powered/recharging from the car, and you can pick up a brand new one along with a cradle and charger from various places for about 50 clams.

I would also add that the constant power thing I mentioned is a real plus. Otherwise (with most palms), you're gonna be replacing batteries or pulling them out to recharge them. The IIIc has a built in rechargable battery that is designed to be recharged from the cradle. So you can modify your palm's cable to apply power from a permanently wired car charger hidden in the console or whatever... when your logger is plugged into the car, it's always powered and charging. (I'm lazy and hate changing batteries )

 

[bling5tatus]

Hey Calan, can you teach me how to charge/power the palm while it's plugged in for logging. That is my only problem right now, my palm doesn't hold a charge as long as I'd like it to... and I'd like to use it for the alarms it has so it'll beep at me if things start going awry.

 

[hsk8te2006]

What kinds of things do I need to watch out for if I remove the WGS restrictor and use a MBC to turn the boost up a pound or two on my GS-T? It is stock except for a cone intake, and I have a 1g BOV I plan to install shortly first. Basically, why do I need a datalogger in the first place sicne I do not plan to tune the timing or fuel systems? (or is adjusting th timing and fuel systems neccessary to be safe on a stock GS-T boosted by a few more pounds?)

Thanks
Jonathan

 

[delta448]

If you have a WBO2, an EGT gauge is pointless. Both are only really useful if you're tuning your car, such as with DSMLink or an SAFC.
EGT is there to give a rough guesstimate if you're running too lean or rich, by looking at the output temperatures. If it gets too hot, likely too lean unless you're washing the cylinders with fuel in your tuning solution.
With a WBO2, you can see exactly how lean or rich you're running. With a good mixture, you won't run hot, so there's no need to have an EGT.

If you're not looking to actually tune, EGT and WBO2 are pretty pointless to have, unless you just want yet another gauge to show off.

Unless you're tuning, the EGT is just yet another gauge. You'd do a LOT better to invest in a datalogger cable instead.

I respectfully disagree about the functionality of an EGT gauge.

I bought an EGT gauge for a reason you did not mention. An EGT gauge can tell you when you have a problem or if conditions are dangerous to the engine. I know, you're thinking the WB does that too... well sorta. The WB tells you when the engine as a whole -on average- is running rich/lean, it doesn't tell you how hot the leanest cylinder is though. You can have 1 cylinder rich, 2 cylinders perfect and 1 cylinder running dangerously lean. If you know the temperature limit of the pistons and valves you can monitor the lean cylinder's temperature to avoid failure.

On DSM 4G63's most people assume the leanest cylinder is #1 since it's injector is last to be fed from the rail (stevetek fuel page). There are at least a couple people though that believe cyl #2 is the hottest. I haven't done a side by side comparison so I honestly don't know. But at least give me some credit for pointing out the concept.

 

[Talesin]

Right. If you have an EGT gauge hooked up to each runner (so four EGT gauges), it'll tell you when a particular cylinder is having a problem. This has been suggested before as the only time an EGT would actually be useful, though I can't remember if Buschur or Shep said it. :b

So about $130x4 = $520, just to see when one cylinder got fuel-starved for a second, or might have a compression problem, or a failing injector, or any of a number of reasons why the temperature would spike on a particular piston. But it still won't tell you if that cylinder is running rich or lean, just that it got hot for some unknown reason.
Not exactly what most who are going the EGT 'cheapass' route are looking to shell out for, but if you're going for a fully-built drag car, more power to you.

 

[nightspeed87]

On DSM 4G63's most people assume the leanest cylinder is #1 since it's injector is last to be fed from the rail (stevetek fuel page). There are at least a couple people though that believe cyl #2 is the hottest. I haven't done a side by side comparison so I honestly don't know. But at least give me some credit for pointing out the concept.

Id say number two since thats were they put the knock sensor behind and also because when i check my plugs thats always the whitest one.
And personally I perfer the wideband, and yea one cylinder or two will run leaner but thats why I dont run a particularly lean overall airfuel ratio to begin with.
11:1 to 11:5 is still rather rich, and is as lean as the most of us on pump gas setups need to go.

 

[delta448]

Right. If you have an EGT gauge hooked up to each runner (so four EGT gauges), it'll tell you when a particular cylinder is having a problem. This has been suggested before as the only time an EGT would actually be useful, though I can't remember if Buschur or Shep said it. :b

I think maybe you missed the idea or misunderstood my post. You only have to watch the hottest cylinder, as long as you know which one it is.

So about $130x4 = $520, just to see when one cylinder got fuel-starved for a second, or might have a compression problem, or a failing injector, or any of a number of reasons why the temperature would spike on a particular piston.

The reason you want to know isn't to diagnose a problem, but to see the gauge and avoid destroying your motor if there is a problem.

Not exactly what most who are going the EGT 'cheapass' route are looking to shell out for, but if you're going for a fully-built drag car, more power to you.

I take offense in being called a cheapass, especially when it's off-base. I in no way ever said that an EGT gauge should replace a WB. A WB is very essential for tuning and if you can only afford one of the two, you should certainly get the WB. However, if you feel that spending a little bit more money is worth a little more peace of mind -as I do, an EGT gauge is not an unwarranted extra cost. Would I ever use one to tune with? -Not a chance in hell, the gauge doesn't react anywhere near as quick or as precisely as the WB. But it is useful to spot a trend or a gradual problem in enough time to shut down and save an engine. Seriously, how many people leave a WB hooked up in the car at all times? An EGT is just a way of keeping an eye on things for less cost than replacing burnt up WB sensors.

 

[hsk8te2006]

I appreciate the debate over the need or use of an EGT vs. a wideband, but noone really answered my recent question...

What is needed (safety and budget are my 2 top concerns) to safely up the boost in a mostly stock GS-T (with a 1g BOV) by a few psi beyond removing the WGS restrictor by using a manual boost controller?