charge pipe questions
 

Hey, on my cold side pipes, i have 3 holes that need to be drilled for taps. I have the BOV, AIT sensor, and WI. In what order should they be placed?

BOV goes on the hotside Tom unless you are going to recirculate. And WI goes just by the TB Do not inject pre turbo period. AIT should be after the WI if you are going to run something to pull timming for heat etc. GL man

im using megasquirt. So i can put my AIT closest to the TB, the WI before that and the BOV near the turbo? is around a foot from the trubo okaY?

I think he means the cold side of the intercooler, or of the engine, anyway.

You want the BOV to be near the throttle body, not back by the turbo. The idea here is to keep the column of air in the charge pipes moving during a blowoff, rather than causing it to come to a standstill.

Are you also running an intercooler, or just WI?

Why would the BOV go on the hotside(pre-IC)? I thought the consensus (this year) was after the intercooler since air acts as a spring and would reduce spool since it'd be flowing backward through the IC when the BOV opened.

Or are you calling anything after the turbo hotside? From the title of the thread "charge pipes" I figured we are talking about only pipes AFTER the turbo so that meant HOTside is before the IC and COLDside is after the IC. In which case he was correct originally in putting them all on the coldside, he just wanted to know the order.

Forgive my ignorance

of course "no intercooler" throws my post right out the window but his signature does say he currently has an rx7 IC but is looking to sell it for a better one.

I thought he was gonna go pre turbo with the BOV i made no assumptions about IC or no IC And yes since i don't run a IC i consider anything after the turbo to be the hot side it simplifies things ;)

Dow.tom, it's your turn. The moro info you give us the better advice we can give you.

Reminds me of the guy a while back who wanted to recirculate the BOV back into the charge pipe between the turbo and the I/C inlet. Or this guy who thought that a BOV was incompatible with a WG, since they both vent pressure. :gay:

ROFL @ WG=BOV guy!

But as for the sensor/WI placement.. should the IAT go right downstream of the WI, or would putting the sensor downstream and 180* from the WI nozzle be a good idea? I've heard it discussed that the water droplets landing on, and evaporating from (sometimes [presumably] after the WI stops) the IAT will give a falsely low reading. I'm thinking maybe my idea would allow the IAT to measure the temp drop from the WI without getting soaked.

So long as it gets a good air flow it doesn't matter but not being bombarded with Meth/water is a good idea.

I've no first-hand experience here, but it seems to me that you don't want the IAT sensor being bombarded with water droplets for the very reason stated- they will tend to throw off the reading.

The following is pure speculation, based upon what I consider to be logical assumptions:

I find it difficult to believe that there is a significant cooling effect upon the air in the charge pipe during the short distance between the WI nozzle and the TB. The water, while presumably well-atomized, simply does not have a tremendous incentive to evaporate during the few milliseconds that it spends in the charge pipe. Placing the IAT into the far end of the intake manifold might produce a slightly more accurate reading (giving the water slightly more time to linger in the air), though I question both the practicality and the gain of that solution.

I have always tended to believe that the majority of the heat transfer (from the air to the water) takes place during the compression stroke inside the cylinder. This is where things *really* heat up, after all. On a 9:1 engine, the heat generated during the compression cycle (in terms of delta-t) is going to be similar to the heat that would be generated by a turbo putting out well over 130 PSI. Think about it- what numbers do we expect to see when we do a compression test?

During the compression stroke there is more than enough heat to cause instant vaporization of the water, and it's that vaporization, and not the mere presence of the water, that cools the air. By definition, the water hasn't absorbed much heat if it's still a liquid in atomized form- it is the process of converting the water into steam that consumes significant energy from the surrounding environment.

i plan to run only WI . But i use cold side as the intake side of the engine bay. My mistake for the confusion. My question was simply what order the 3 should go in, and how far spaced apart should they be?

From turbo to throttle body i would put them IAT, BOV, WI nozzle. That is unless you want to run a closed element IAT sensor vs. an open element one. If you wanted to run a closed element sensor and install it after the WI you could actually see what temps you were running after the WI cools the intake charge. The closed element sensor responds slower but it would work alright. We normally use the open element sensors because they respond faster but I've read that when injecting methanol it is best to not let it spray the element on the sensor because it can damage it. That could all be BS though. I still think you should run an IC though.

I spray across the sensor. Stick the BOV wherever you want. It doesn't really matter.

So you haven't seen any open element sensor damage with users spraying meth across it?

okay, i think i know what i plan to do, please give comments on how oyu think this will work. I want to put hte AIT sensor RIGHT BEFORE the TB. than have a 90 degree bend(toward hotside of engine bay). From there i want to place the WI nozzle on the 180 section and the BOV in the center between the WI and the Turbo (kind of in the middle of the 180degree bend).

comments. concerns?

Do it. Take pictures. Sounds fine to me.

question now. i cut the pipes. I have a 1inch Bosch BOV so i know i need a one 1nch hole and a little piece of 1in pipe for that. but what size holes do i drill for the AIT sensor that came from MS pnp and the WI nozzle?

3/8 NPT is the tap you want to use 9/16 drill should work for that.