maf relocation

[nando]

this is true for a close system like a compressed air tank, but an engine is far from a closed system since it flows air pretty quickly, boost is just flowing more air than the engine can let though resulting in a positive pressure.

uh.. no. Do you know what atmospheric pressure is? Boost is basically increasing the atmospheric pressure the engine sees. If you ran an engine on a planet that had a 2 bar atmospheric pressure, it would run the same as a boosted engine running 1 bar of boost on earth.

[Tchao]

^ Dude just shut up. Your bull shit has no meaning here.

A MAF is actually easier to tune with on a M/S50 motor then MAP. There are lots of advantages with MAF then MAP.

[nando]

^ Dude just shut up. Your bull shit has no meaning here.

A MAF is actually easier to tune with on a M/S50 motor then MAP. There are lots of advantages with MAF then MAP.

huh? I didn't say anything about map/vs maf in that post.

but if you think boost is the pressure that the engine can't suck in.. okay. ;)

and anyway what I meant by MAP being a little easier to work with is there is no confusion as to where the sensor goes. A line to anywhere within the manifold, done.

[Tchao]

If you want to get technical, shouldnt be put into runner, TB inlet, near major ports like ICV's etc. Pressure maybe the same in a static world. But not when theres flow, restrictions, pressure pulses, heat, etc....

A MAF only belongs before the turbo, as thats the total air going into the motor. Just as you would for AFM.

[Jaxx_]

A MAF only belongs before the turbo, as thats the total air going into the motor. Just as you would for AFM.

There's nothing wrong with a blow-through MAF if you vent to atmosphere... :roll:

thanxks jaxx thats what i was thinking just to get an even reading but im not sure i want it to be were the incoming air threw tb directly hits it since that is were its flowing the fastest and hitting the plenum to basicly split into both sides, but i guess any tuning program i find for this motor woulnt be that precise.
this will be after a bigger turbo and thottle btw

I wouldn't worry about it that much. If you want to get that serious you should be doing EGTs and AFRs on each cyl. Not cheap, nor cheap to fix if the sensors fail and hit the turbo. Don't mess with it unless you're trying very hard to get the last few ponies out of your already maxed out setup. That, or you're tuning for super enduros or high-rpm Autobahn blasting.

Carb'd engines have this problem all day long-- it's not uncommon to see 1 cyl has EGTs of 700 while another has 1000.

[Tchao]

If that was the case then why do all DME tuners (TT, TRM, NickG, etc) use pull though, why do all OEM FI application that utilizes a MAF run pull though?

With (at least DME) MAF's you can set the target air to fuel ratio and let the computer do the rest. This is how the DME is programed and I would almost bet his tune from TRM says the same.

[Jaxx_]

If that was the case then why do all DME tuners (TT, TRM, NickG, etc) use pull though, why do all OEM FI application that utilizes a MAF run pull though?

With (at least DME) MAF's you can set the target air to fuel ratio and let the computer do the rest. This is how the DME is programed for and it I would almost bet on his tune from TRM says the same.

because most tuners won't vent to atmosphere. I think the real issue is longevity. blow through maf will end up getting a lot of oil on it from the PCV system and turbo oil seals if they leak.

Plus, a MAF closer to the throttle body will let the motor have better throttle response.

[Tchao]

Throttle response is determined by tuning, not how close the MAF is.

Either way the OP needs to contact TRM.

[dranttna]

uh.. no. Do you know what atmospheric pressure is? Boost is basically increasing the atmospheric pressure the engine sees. If you ran an engine on a planet that had a 2 bar atmospheric pressure, it would run the same as a boosted engine running 1 bar of boost on earth.

this is not true at all, that would mean it has that pressure on the exhaust side also and the engine would run just like it does on earth. boost is haveing more pressure on the intake side than the exhaust. if your turboed, go stick a pressure gauge on the collector and see what the pressure is for yourself.
i will be calling trm as soon as i get a chance.
im not saying one maf location is better than the other, but i did move it to blow-threw and pull-threw just to see what would happen and they are about the same. the 5-gas says its alittle bit richer at 3k rpm and up with the blow trough setup but this could be due to a hidden vacuum leak on hte pull-threw. im going to do a smoke test tomorrow just to make sure then retest

[Jaxx_]

Throttle response is determined by tuning, not how close the MAF is.

If you said MAP, this would be true, however, MAF reads the air volume before all that air gets pushed all the way though the turbo, IC charge pipes, intercooler and throttle body. Practically speaking, this is why the length of charge pipes and intercooler size/style matters. The ECU will compensate for the air flow before it's reached the motor. No amount of tuning can predict throttle input.

[Tchao]

Doesnt matter, the TPS reads any input the fastest, and at a few thousand times a second, it can predict you are WOT before the TB is all the way open when you smash it.

[dranttna]

i didnt notice any thottle responce changes either way, the tps is the first input to the ecu, there is a delay for the ecu to proccess the other sensors inputs befor it starts compensating and adjusting the inj pulse wdth and timing. i could tell that it spooled up slightly faster with the blow-threw setup though. even though it makes alot more sence to have it pre turbo since it would be metering all the incomeing air it takes to make the boost pressure... ultimatly i will find out tomorrow what works best on my setup, others may be differant

[dranttna]

okso the smoke machine releaved that the control solenoid for my ebc spit the plug out of the back which caused a huge boost leak. fixed this and then went for a test drive, with the blow-though it cut out pretty hard at 4k and 1/2 throttle. with the pull-though it cut out even harder at 4k with 1/2 throttle but then died instead of going to idle... more thottle makes it cut out sooner, with 1/3 thottle it doesnt cut out. no leaks, good fuel pressure, i have no fuckin idea whats goin on. this is pissing me off

[dranttna]

ok so i pulled my almost brand new plugs and they were fried. so i threw in a set of bosch plugs and holly shit... i wasnt expecting it to pull all the way though so it was alittle scary haha but the fun scary. so note to self, dont use autolite plugs. i've been chaceing this problem forever. btw the pull-though is deff the way to go now that its fixed.

[Tchao]

Keep in mind you need to keep the MAF where the tune in your DME is made for. A blow though senses a lot less air flow then a pull though (preturbo).