Where can i buy a EMAP sensor?

[JamesWolak]

I am looking for a EMAP sensor for our turbo setup, does anyone have any experince with these and where i should buy one? I did a basic search and came up with nothing but i am sure i was searching in the wrong location.

Thanks,
Wolak

[JamesWolak]

I am looking for a EMAP sensor for our turbo setup, does anyone have any experince with these and where i should buy one? I did a basic search and came up with nothing but i am sure i was searching in the wrong location.

Thanks,
Wolak

[Pete M]

Basically, a purpose built EMAP sensor would be quite expensive if you were actually talking about a sensor that could be mounted to the headers and stand the heat, etc. Most people just use a MAP sensor of some description and use a relatively long metal pipe coming off the headers to protect the sensor from the heat. Because the gas in the tube doesn't really flow, there isn't much conduction of heat. You might be able to get away with a 3 bar sensor although we use a 5 bar.

[JamesWolak]

Thanks Pete. I have read about similar setups but never looked into it further. How do you have the tube attached to the manifold? I am thinking i would like to do it with a bung that the tube screaws into. I would say just weld it on but this will be on our comp manifold.

[Pete M]

I'd weld a fitting on and make the tube removable. We actually have ours tapped into a boss on the turbine housing but only because that was easier than welding something to the headers.

[JamesWolak]

Pete I am going to assume that your not running a GT12. Or are you?

[Pete M]

Nah, GT-15V. I'm guessing from the question that the GT-12 doesn't have the little boss thingy in the casting? On the 15 there's one on the back of the scroll, below the exhaust manifold flange, just a slab of extra meat you can drill and tap.

We have previously had it going to a fitting welded to the headers though and as far as i know that worked ok.

[drivetrainUW-Platt]

Whats an EMAP sensor? Same as a map sensor? You would want a 2 bar or 3 bar map sensor if thats what your talking about.

[Pete M]

Exhaust Manifold Absolute Pressure. But yes, as i mentioned, you typically just use a MAP sensor that can read appropriately high.

[JamesWolak]

Pete was there any precaution taken in the heat range of the MAP sensor most are around 200F max.

[Pete M]

Yeah, run a long pipe to it. Our sensor uses a 1/8 NPT fitting to attach to the pipe, which is about 40 cm long (go longer if you're scared). If you're using a more conventional 3 bar MAP sensor, then you'll need a bit of rubber hose from the end of your pipe to the sensor. The reason it works without frying the sensor is that there is no continuous flow between the headers and the sensor. Air/exhaust is a pretty good insulator of heat and thin wall stainless tube won't conduct far before the heat is rejected to the surrounding air. Of course, if you have a leak at the sensor end of the tube, you'll probably fry the sensor pretty quickly, so make sure there isn't one.

We've been using the same EMAP sensor for over 2 years now and it hasn't failed yet. Not promises of course, but the idea seems to work fine.

[JamesWolak]

Thanks Pete, we will be doing this shortly.

[drivetrainUW-Platt]

Why would you want to measure your exhaust pressure instead of your manifold pressure?

[Pete M]

Who said anything about instead of? Naturally, you still have a MAP sensor. EMAP is a very important quantity on a turbo car as excessive EMAP will have quite a large effect on power.

[Discretely elite]

Pete, I am from LTU as well. I am curious if you use your EMAP readings in conjunction with MAP readings to determine your efficiency(load point)? On MoTec there is a load setting for such a setup but it warns against pulsations which may cause fluctuations in load calculations. Also it seems that the pipe necessary to connect the EMAP sensor is impractical to install in the car.

Currently we plan to use it as a logging tool only.

[Pete M]

We tried MAP/EMAP tuning on the dyno once. You have to filter the hell out of EMAP to make it sensible, and if it misfires, that may lead to an incorrect mixture which may make it misfire more. Also, even though we haven't had any problems with it, i wouldn't be game to make the EMAP sensor something we relied on for the car to run, it seems too dodgy.

I also think there is a problem with not having at least one of your axes highly correlated with load. MAP/EMAP vs RPM means that you're relying very heavily on your MAP compensation, and hence on having your injector dead time set very accurately. Whereas having MAP or TP as your fuel table axis means you're relying less on the compensation because, for example, at a certain TP you're usually at a certain MAP. So slight errors just get reflected in the fuel table.

Long story short, we abandoned it. It's supposedly theoretically a good way to tune but it's got a bunch of practical problems that we didn't feel were worth solving.

We've run our EMAP sensor in the car too, you can coil the pipe to make it take less space. I don't know if it's something you'd want to have on for comp though for weight reasons.