ITBs and MAT sensor

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Six_Shooter
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ITBs and MAT sensor

Post by Six_Shooter »

I'm converting a Crower mechanical intake to EFI.

The only thing that I can't come to a solid conclusion on is the location for the MAT sensor.

I will not be running a common air filter housing so that idea is out.

What I have come up with is placing it in the #7 runner because I there's space to do so, it will be somewhat hidden and should be pretty indicative of what the air temp is entering the cylinder.

What have others done in a similar situation?

I suppose I could simply make a bracket that holds the MAT near the engine and be somewhat close to the air temp entering the cylinders. This is on a T-bucket, so no hood, no enclosed engine compartment to speak of so heat soaking shouldn't really be an issue.


Any problems with the MAT sensor only being in one runner?

Pictures for reference (Ignore the coolant temp sensor, it's all I had handy at the time):
MATLoc01.jpg
MATLoc02.jpg
Tha Toy: 1973 Datsun 240Z Turbocharged, and loads of fun, now MS'd
Tha Otha Toy: 1923 T-bucket Hot Rod, Currently Sniper'd
Tha Daily: 2005 Chevy Blazer
Tha Summer Daily: 1987 Buick Skyhawk hatchback
Tha Long Term Project: 1985 GMC S-10 Jimmy, hasn't been fun for a while
whittlebeast
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Re: ITBs and MAT sensor

Post by whittlebeast »

If this thing is a NA motor, mounting is close to the air filters and call in go.

Andy
billr
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Re: ITBs and MAT sensor

Post by billr »

I think putting it in one runner will be reasonably accurate. Regardless of where you put it, consider one of those small GM ones with 1/8" MPT (Standard Motor Products #TX73). You can hide that easier...
CRSTune
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Re: ITBs and MAT sensor

Post by CRSTune »

Or the open element air temp sensor if we're talking about smaller units:
http://www.t1racedevelopment.com/t1-mot ... ensor.html
(AEM and a couple of other locations also have them available)

Notes:
1/8" NPT
2 Pin Deutsch DTM Connector
Open Element
GM Calibration
I'm in the VA/DC area! Let me know if I can help you locally! I offer tuning and troubleshooting services.
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whittlebeast
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Re: ITBs and MAT sensor

Post by whittlebeast »

Here is a pic of mine. Top center of the photo. I prefer to not have anything that could possibly wind up in the motor and can run into serious hear soak issues. This does not work on boosted motors.

http://www.nbs-stl.com/CrxTypeR/B18C%20Side.jpg

Andy
Six_Shooter
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Re: ITBs and MAT sensor

Post by Six_Shooter »

whittlebeast wrote:If this thing is a NA motor, mounting is close to the air filters and call in go.

Andy
I think you may have missed this part:
Six_Shooter wrote:
I will not be running a common air filter housing so that idea is out.
I'm trying to find some air filters that will flow enough and be down IN the tubes. I've found ones that are the right shape to work, but I have no dimensions yet... detail for later at this point. I REALLY want the open stack look. Any filters on top, even those flat ones that sit on the top of the tube just ruin the look for me.

If you're saying mount it near the top of the tubes, that's a no go, while it would be more accurate to what is being commonly pulled in for air temp, it would be ugly and look very out of place. Although I am making a bracket for something else where I could possibly incorporate the MAT sensor into it and MAY not look out of place...
billr wrote:I think putting it in one runner will be reasonably accurate. Regardless of where you put it, consider one of those small GM ones with 1/8" MPT (Standard Motor Products #TX73). You can hide that easier...
That's my thought too, while it may not be completely accurate for all cylinders it should be good enough for the intended usage, which is a street rod, no racing, no very cold days (no top and a windsheild that is lower than my head makes it REALLY cold when the temp is low), just a cruiser.

I'll look at that sensor you mention, but I have several of the standard 3/8" NPT and even made the bung for one earlier tonight to weld to the intake...
Last edited by Six_Shooter on Sun Dec 25, 2016 12:04 pm, edited 1 time in total.
Tha Toy: 1973 Datsun 240Z Turbocharged, and loads of fun, now MS'd
Tha Otha Toy: 1923 T-bucket Hot Rod, Currently Sniper'd
Tha Daily: 2005 Chevy Blazer
Tha Summer Daily: 1987 Buick Skyhawk hatchback
Tha Long Term Project: 1985 GMC S-10 Jimmy, hasn't been fun for a while
Yves
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Re: ITBs and MAT sensor

Post by Yves »

MY experience with my ITB's is that mounting it in the intake manifold makes it susceptible to heat soak.

If your are running no air filters and just sucking in hot underhood air, you would be better off to mount it somewhere in the area where the stacks are but not connected to the motor. Like the firewall.
I use airboxes and they draw air through 2 pairs of tubes that are fed by a cone filter. I mounted my iat in the tube coming off the cone filter. This is the air temp that the motor actually sees (maybe it will heat up small amount in the airboxes, but that's about it. It works.
Dennis_Zx7r
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Re: ITBs and MAT sensor

Post by Dennis_Zx7r »

I mounted my MAT above one ITB at first. The problem was, that during transient, it would sometimes cause some of the mixture coming back into the airbox, cooling the sensor several degrees. This resulted in spikes in the fueling calculations, and I therefore mounted the sensor more towards the inlet of the airbox, where it worked fine.
This was even with a closed plastic sensor element.

I know a guy who mounted an open element sensor inside an ITB with an open element, who had the same spikes. In his case the spikes were a magnitude worse, so he couldn't use MAT correction at all. The sensor data in the logs looked horrible and was pure noise, with spikes even reaching -35°C below ambient temperature.

Because of this, I personally would aim for measuring the pure airr, and avoid getting mixture near the sensor.

In any case, I would not put air filters IN the ITB. The surface for the mixture to pass through would be extremely small resulting in possible severe performance loss. Even worse, they might loosen und prevent the throttle blades from closing.
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Yves
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Re: ITBs and MAT sensor

Post by Yves »

Try mounting it in between the runners. Shouldn't be too far of from what the runners see as a far as air temp is concerned.
whittlebeast
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Re: ITBs and MAT sensor

Post by whittlebeast »

Spikes in the MAT are almost always a wiring issue and not a true spike in air temp. Keep in mind that MAT as far is the code is concerned is temperature absolute. That works out to 460 degrees below 0 F. So the difference between 90 and 100 F is

(460+100)/(460+90) = about a 2% change in fueling.

With noise setting in at -35 C or -31 F

(460-31)/(460+100) = about a 25% change in fueling.

Being dead on in the MAT is not a show stopper. Noise in the MAP can be a real issue.

Andy
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Re: ITBs and MAT sensor

Post by whittlebeast »

I happen to own an ITB racecar that idles in line for about 2 min followed by about 50 sec of pure abuse.

The MAT will rise about 10 degrees as we are in line at very low speed. When we launch on course, the MAT drops at a very steady back down about 10 degrees F as we hammer the motor. The CLT normally maxes out about 15 sec into the run. There are no spikes in either the MAT or CLT.

See http://www.nbs-stl.com/CRX/Engine%20Tem ... Course.png

The noise you see in the MPH is the nature of the GPS signal that I am feeding the ECU.

Andy
Six_Shooter
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Re: ITBs and MAT sensor

Post by Six_Shooter »

I had completely forgot about fuel...splash(?)... vapour misting(?)... whatever you want to call it cooling the sensor causing inaccurate readings. The location I had proposed this could be a very real issue, especially if I run batch fire (most likely at this point, since there will be no cam sensor signal to start with. I may switch to sequential later) and at low RPM /throttle closed situations.

Again, this is a street rod with ZERO chance of being raced. T-bucket with no roll bar (Though it used to have one and would like to build another one to replace the one that my Uncle and I built for it), no hood, so "underhood" heat soaking is not an issue. So my concern is mostly idle, low throttle angle cruising and transitions from idle up. I'm not saying it won't see WOT, because it definitely will, but it will only ever very briefly be there. So max HP or performance is not really a concern. I know you're probably asking why I am putting this set up on then. Well, because I can, and because it's how my Uncle wanted the car, though it was originally mechanical, I'm going EFI just to make the street manners better.

I I think I'll go with a mounting location not in a runner. I'm making a mount for a fuel pressure gauge that I should be able to incorporate an IAT sensor into and still look decent.

As far as the filters are concerned, I've found some that will have sufficient surface area to feed the engine, they are designed for engines that displace more than twice what each cylinder has in my engine. I just need to get some dimensions to know if they will fit or not. If these filters interfere with the throttle blades I have bigger issues to worry about then. They will be at least 1.25" above the throttle blades, likely more. Again, this engine is not about performance. I understand from a performance standpoint a single filter feeding all cylinders is better due to constant air flow through the filter being easier to pull air in versus the starting and stopping of air flow for each cylinder. If this was a race application I'd do the air filtering very differently.

For reference, this is the car and a picture of the mechanical setup.
2016-08-15-01.crop.jpg
PAR-T3.jpg
Tha Toy: 1973 Datsun 240Z Turbocharged, and loads of fun, now MS'd
Tha Otha Toy: 1923 T-bucket Hot Rod, Currently Sniper'd
Tha Daily: 2005 Chevy Blazer
Tha Summer Daily: 1987 Buick Skyhawk hatchback
Tha Long Term Project: 1985 GMC S-10 Jimmy, hasn't been fun for a while
Dennis_Zx7r
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Re: ITBs and MAT sensor

Post by Dennis_Zx7r »

That thing looks nice. I personally don't think the airfilter in the first picture lessens this, and I would be concerned about little stones or debris from the road getting in there, especially with the open wheels. However, that's of course your decision.
I think I would place the MAT somewhere in the vehicle where there's no chance of heatsoak, and it can pick up the ambient air temperature. Or somewhere between the funnels, although there might be heatsoak. Looks like the temperature of the air going is going to be nearly ambient temperature, at least when the car's not standing still.
Six_Shooter wrote:I had completely forgot about fuel...splash(?)... vapour misting(?)... whatever you want to call it cooling the sensor causing inaccurate readings. The location I had proposed this could be a very real issue, especially if I run batch fire (most likely at this point, since there will be no cam sensor signal to start with. I may switch to sequential later) and at low RPM /throttle closed situations.
Two examples, both naturally aspirated engines.

This would be something typical, less extreme data of the sort I mentioned. MAT sensor open element, mounted in the ITB.
Image
What you can see is that it's down to 6°C after a little load, and climbs back to 20°C after 10s, when back to idle.

The following is with the closed MAT sensor, mounted above one ITB (running semi-sequential). You can see it gets back to it's expected value like an e-function when the "misting" stops. Also note it drops to -8°C, ambient temperature is 28°C. This is not electrical noise, could be reproduced nicely and was solved by moving the sensor a little, as already mentioned.
Image
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Six_Shooter
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Re: ITBs and MAT sensor

Post by Six_Shooter »

Dennis_Zx7r wrote:That thing looks nice. I personally don't think the airfilter in the first picture lessens this, and I would be concerned about little stones or debris from the road getting in there, especially with the open wheels. However, that's of course your decision.
I think I would place the MAT somewhere in the vehicle where there's no chance of heatsoak, and it can pick up the ambient air temperature. Or somewhere between the funnels, although there might be heatsoak. Looks like the temperature of the air going is going to be nearly ambient temperature, at least when the car's not standing still.
I'm not sure what picture you're referring to as the "first picture". If you're referring to whittlebeast's Honda, that will NOT be happening on my car, there are different filters that can be placed on the top of the ram horns I have and even they take away from the look IMO.
There are these styles and variations of:

http://www.ccookenterprises.com/assets/ ... all-01.jpg

http://s13.photobucket.com/user/bobcowa ... l.jpg.html

That are easy to get, and work, I just don't like the look of them, I want to keep that open ram horn look.

If you're referring to the picture of the T-Bucket in the parking lot, that's a TBI setup on the car that was there only to get rid of the carburetor last summer, when I was having issues with it, that turned out to be more of a fuel delivery problem due to the fuse block having issues, or so it seems.

Like I said I've found some filters that look right to fit down in the tubes, but I need to get dimensions to know if they'll fit. I also have a couple ideas for simple mesh screens to keep the rocks and small animals out, which is likely what will happen, at least to start with, unless these other filters will fit and then I'll just start with those.

The only other style I'd consider and would still take plenty of custom work is two oval filters similar to this:

http://www.force-efi.com/pictures/BBC%2 ... ilters.JPG

I would have to make my own base plates though as I've only ever seen these for parallel tubes and not angled tubes like I have. But this would be an ABSOLUTE LAST resort. It looks good, just not the look I'm after.
Six_Shooter wrote:I had completely forgot about fuel...splash(?)... vapour misting(?)... whatever you want to call it cooling the sensor causing inaccurate readings. The location I had proposed this could be a very real issue, especially if I run batch fire (most likely at this point, since there will be no cam sensor signal to start with. I may switch to sequential later) and at low RPM /throttle closed situations.
Two examples, both naturally aspirated engines.

This would be something typical, less extreme data of the sort I mentioned. MAT sensor open element, mounted in the ITB.
Image
What you can see is that it's down to 6°C after a little load, and climbs back to 20°C after 10s, when back to idle.

The following is with the closed MAT sensor, mounted above one ITB (running semi-sequential). You can see it gets back to it's expected value like an e-function when the "misting" stops. Also note it drops to -8°C, ambient temperature is 28°C. This is not electrical noise, could be reproduced nicely and was solved by moving the sensor a little, as already mentioned.
Image
Yes, I totally understood what was being said about the fuel cooling the sensor, I just completely forgot about it in this instance. I had only originally considered it a problem when the MAT sensor was down stream of injectors, but it could also be an issue too close up stream.

I've decided to mount it somewhere on/close to the engine, likely in the bracket I mentioned before since it will be somewhat close to the stack openings (at least for the rear cylinders) and should read somewhat accurately of what is entering those stacks, along with being sorta hidden from view.
Tha Toy: 1973 Datsun 240Z Turbocharged, and loads of fun, now MS'd
Tha Otha Toy: 1923 T-bucket Hot Rod, Currently Sniper'd
Tha Daily: 2005 Chevy Blazer
Tha Summer Daily: 1987 Buick Skyhawk hatchback
Tha Long Term Project: 1985 GMC S-10 Jimmy, hasn't been fun for a while
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