# throttle body before a turbo? **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [February 29, 2008, 6:45am UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191 "2008-02-29T06:45:09Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![newman](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/newman/32/7569_2.png) [@newman](https://forums.speedlife.net/u/newman)\ **Post date:** [February 29, 2008, 12:43pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/21 "2008-02-29T12:43:20Z")
> [@Nikuk](#): > > really? I’m not delving deep into it here, but I would assume its almost bass-ackawrds to put the meter infront of the turbo & IC. > > I’ve never done it with a MAF, only with VAMs (think trap door & spring)… and draw through fucking sucked in every way by comparison to blowthrough. Especially once a front mount was introduced. 300zx & skyline & subarus are all draw through setups. ---
**Author:** ![Nikuk](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nikuk/32/7254_2.png) [@Nikuk](https://forums.speedlife.net/u/Nikuk)\ **Post date:** [February 29, 2008, 12:45pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/22 "2008-02-29T12:45:51Z")
> [@newman](#): > > this is called PUMP CAVITATION > **[Cavitation 1-3 – McNally Institute](https://www.mcnallyinstitute.com/01-html/1-3.html)** Liquid based, but same concept. as for the edit: > [@newman](#): > > the maf should read the same voltage on either side of the compressor, but depending on the proximity to the throttlebody, you can develop pressure waves traveling in the opposite direction of the airflow which will disrupt the reading. yea, i would’ve thought density change from ambient (pre compressor) to compressed (post compressor) to compressed & cooled (post comp & IC) would make for differences, no? > [@newman](#): > > 300zx & skyline & subarus are all draw through setups. OIC ---
**Author:** ![newman](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/newman/32/7569_2.png) [@newman](https://forums.speedlife.net/u/newman)\ **Post date:** [February 29, 2008, 12:52pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/23 "2008-02-29T12:52:43Z")
> [@Nikuk](#): > > [Cavitation 1-3 – McNally Institute](http://www.mcnallyinstitute.com/01-html/1-3.html) > > Liquid based, but same concept. Fluid based. Air is a fluid. > [@Nikuk](#): > > as for the edit:yea, i would’ve thought density change from ambient (pre compressor) to compressed (post compressor) to compressed & cooled (post comp & IC) would make for differences, no? yeah, but mass can neither be created nor destroyed. Qin = Qout. here’s information about how a hotwire maf works: (i’ve seen a much more thorough description, but cannot find it now) > **[Air Flow and Mass Sensing Devices](https://www.knfilters.com/maf/mafdevices.htm)** > > Factory direct K&N replacement air filters, air intakes, oil filters & cabin filters. KNFilters.com - the official site for performance filtration products. > Unlike air flow meters, hot wire or hot film mass air flow sensors directly measure air mass, as the convective qualities of air are affected by factors like temperature, humidity and density. Hot wire sensors create an analog signal and hot film sensors a digital frequency signal. > Most common hot-wire MAF sensors use a platinum wire or filament heated to a prescribed, maintained temperature above ambient, located centrally in the incoming air stream. These sensors function on the electrical principle that resistance increases with temperature. As intake air moves past the wire or film, the cooling effect causes a measurable drop in resistance, and thus lower voltage is required to maintain the prescribed temperature. The hot-wire MAF control unit is sent a reference voltage of 5V, and returns around .4V to.5V at idle and from 4.5V to 5V at full throttle. Based on a fixed data set, an accurate assumption of air mass is made. > Readings can stray from the target values as a result of contamination of the wire and for the sake of accuracy, an additional input from an integrated intake temperature sensor is sometimes used. Many hot wire MAFs incorporate a burn off cycle when the ignition is switched off, heating the element to over 1800-degrees F to clear it of contamination. Hot wire sensors are the most physically delicate and easily contaminated of all the air flow and mass sensors. ---
**Author:** ![Nikuk](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nikuk/32/7254_2.png) [@Nikuk](https://forums.speedlife.net/u/Nikuk)\ **Post date:** [February 29, 2008, 12:57pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/24 "2008-02-29T12:57:50Z")
> [@newman](#): > > Fluid based. > > Air is a fluid. Thats what I said… 😛 Nice, thanks. This is why I stick w/map sensors I suppose. ---
**Author:** ![boardjnky4](https://avatars.discourse-cdn.com/v4/letter/b/96bed5/32.png) [@boardjnky4](https://forums.speedlife.net/u/boardjnky4)\ **Post date:** [February 29, 2008, 1:09pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/25 "2008-02-29T13:09:43Z")
> [@newman](#): > > Carnut could go into more detail than I feel like at the moment, but any restriction to the inlet of the turbo causes HUGE decreases in efficiency. That was pretty much what I was thinking. ---
**Author:** ![Cavi\_Mike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/cavi_mike/32/5217_2.png) [@Cavi\_Mike](https://forums.speedlife.net/u/Cavi_Mike)\ **Post date:** [February 29, 2008, 1:37pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/26 "2008-02-29T13:37:28Z")
> [@Nikuk](#): > > another valid point. Imagine part throttle flow, lol. > > And I imagine that when yo come off the throttle, completly blocking the airflow infront of the turbo would not make for a happy turbo. Actually the vacuum created from cutting off the intake side of the turbo will make it spin easier since it draws the air out of itself and air is the only thing resisting the compressor. Didn’t you ever notice how a vacuum cleaner winds up faster when you plug the hose? Or a hair dryer? ---
**Author:** ![Zer0DazE](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/zer0daze/32/7624_2.png) [@Zer0DazE](https://forums.speedlife.net/u/Zer0DazE)\ **Post date:** [February 29, 2008, 1:37pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/27 "2008-02-29T13:37:57Z")
> [@Nikuk](#): > > [Cavitation 1-3 – McNally Institute](http://www.mcnallyinstitute.com/01-html/1-3.html) > > Liquid based, but same concept. > > as for the edit:yea, i would’ve thought density change from ambient (pre compressor) to compressed (post compressor) to compressed & cooled (post comp & IC) would make for differences, no? > > OIC if i understand the right, a MAF setup NEEDS an IAT, and thats why it doesn’t matter which side it is on. ---
**Author:** ![somedude](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@somedude](https://forums.speedlife.net/u/somedude)\ **Post date:** [February 29, 2008, 2:09pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/28 "2008-02-29T14:09:38Z")
some of you guys are saying turbo lag but are you meaning throttle lag? I realize that there would be a certain amount of throttle lag both on and off the throttle, but there may be a couple of advantages on this application. the stock TB is 65mm and is a restriction so thise would allow for a larger TB. the discussion about blowthroug vs drawthorugh is interesting to read here vs the SHO forum because on there it is more of a heated arguement of 5 people with draw through and 5 people with blow through saying their setup is better when in all reality it makes no difference at all on this engine. Most cases when changing from one setup to another the tune isn’t even adjusted. blow through seems to be more common on our cars though because then we don’t have to worry about shooting flames when lifting throttle at high rpm due to metering unused air. will having the TB before the turbo cause damage to the turbo or will it help keep it spooled when off the throttle due to removing major load from the compressor side. i’m not sure if it will be intercooled. it might be a meth hore. I’m trying to avoid flipping the intake around because you have to use a spacer to lift the intake to clear the timing belt and that lowers the torque curve in the rpm band. > [@ubengineering](#): > > BOV’s arent rocket science, they even come with instructions > > dont try to be mr. innovative You are not familiar with my car are you? ---
**Author:** ![Cavi\_Mike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/cavi_mike/32/5217_2.png) [@Cavi\_Mike](https://forums.speedlife.net/u/Cavi_Mike)\ **Post date:** [February 29, 2008, 2:17pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/29 "2008-02-29T14:17:31Z")
A slightly undersized throttle body isn’t as big of a deal on a blow-through setup, they’re actually usually larger on lower hp, n/a cars. Why are you so bent on doing a draw-through? ---
**Author:** ![reliant\_turbo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/reliant_turbo/32/7189_2.png) [@reliant\_turbo](https://forums.speedlife.net/u/reliant_turbo)\ **Post date:** [February 29, 2008, 3:09pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/30 "2008-02-29T15:09:39Z")
yeah the 84 through 87 non intercooled dodges had this setup. i know you other dodge guys had laggy setups like this but ive seen them be very responsive when you take the boost control away from the ecu as the distance from the compressor output to the intake manifold is one inch. its probably more the ecu boost control (limits boost till 3-4k) and the intake manifold being garbage on the older cars. one other caveat. all the piping must be hardpiped with very little rubber left unsupported internally as the system sees full vacuum. another thing is that a popped off intercooler hose = rev to the moon. if you use large piping from the throttle plate to the turbo and a large TB, it should work pretty well. Brian ---
**Author:** ![Nikuk](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nikuk/32/7254_2.png) [@Nikuk](https://forums.speedlife.net/u/Nikuk)\ **Post date:** [February 29, 2008, 5:28pm UTC](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191/31 "2008-02-29T17:28:30Z")
> [@Zer0DazE](#): > > if i understand the right, a MAF setup NEEDS an IAT, and thats why it doesn’t matter which side it is on. then it all makes sense, :tup: [Previous page](https://forums.speedlife.net/t/throttle-body-before-a-turbo/44191.md?page=1)