Pros and Cons of Blow Through vs Draw Through Mass Air Meter
Guys, since I'm redoing my whole intake/intercooler setup, whats my best bet here? What are the pros and cons of each? Which is going to give me the most accurate tune?
A blow through allows venting excess pressure to air. Draw through requires a bypass valve. The amount of air going over the meter is what the tuner needs. Weather it is pressurized or not the meter will capture that info and the tuner will adjust settings accordingly. For the best tune both systems will need an accurate reading of the inlet air temp.
A blow through allows venting excess pressure to air. Draw through requires a bypass valve.
Jean Marc Chartier
Both will have to have a bypassvalve, just a matter of where it vents to. I'm just trying to figure out which one gives the most driveable features, ease of tunability, and consistency. Like with the draw through, you have to deal with backwash on the MAM, potentially... Just trying to figure out all the issues with each option. Seems like most people prefer the blow through.
I've been blow thru for a while, and it is so much easier to deal with. I have a 3" Pmas tube mounted in the pipe between the intercooler and throttle body, about at the water pump. This is the longest straight shot of air.
Set up like this, you do just about whatever you want an the other side of the intercooler. I have a Mini race bypass and waste gate vented to atmosphere, but all the maf sees is what comes through the IC, which is very stable.
I had nothing but trouble trying get the Lmaf to work with a large recirculating bypass in draw thru config.
I've been blow thru for a while, and it is so much easier to deal with. I have a 3" Pmas tube mounted in the pipe between the intercooler and throttle body, about at the water pump. This is the longest straight shot of air.
Set up like this, you do just about whatever you want an the other side of the intercooler. I have a Mini race bypass and waste gate vented to atmosphere, but all the maf sees is what comes through the IC, which is very stable.
I had nothing but trouble trying get the Lmaf to work with a large recirculating bypass in draw thru config.
Thats one of the issues I was wondering about. My Mass Air is a BA2400 which is 4" and my intercooler will be 3" pipe. I'd like to go to a blow through but not sure if going from a 3" tube to a 4" mass air really makes any sense. Might cause some issues going from a 3" to a 4" section then back down to a 3". Or I could just go from 3" up to the 4" and then go straight into the throttle body and neck it down to 3" with the MAMeter right in front of the throttle body.
Thats one of the issues I was wondering about. My Mass Air is a BA2400 which is 4" and my intercooler will be 3" pipe. I'd like to go to a blow through but not sure if going from a 3" tube to a 4" mass air really makes any sense. Might cause some issues going from a 3" to a 4" section then back down to a 3". Or I could just go from 3" up to the 4" and then go straight into the throttle body and neck it down to 3" with the MAMeter right in front of the throttle body.
The BA's are nice mafs.
I doubt that a 4" will fit in front of the engine, at least it wouldn't on mine but you may have more room.
I'm just not sure about the 3/4/3 transition, but probably would be a problem unless the 4" sections were long enough to let the air flow. I don't see that with our set ups.
iv been usein a 90mm draw through mass air for some time now with no problems. I puy my mass air between the throttlebody and I/C right in front of my electric fans and my blow off between my my I/C and my supercharger. Works well for me
This pic you can see my blow off routed back to my superchager inlet but know its vented to the atmosphere.
These pics are old but the mass air is now where the blue intake clamp is
Last edited by justin mccluske; 09-21-2008 at 04:00 PM.
Thats one of the issues I was wondering about. My Mass Air is a BA2400 which is 4" and my intercooler will be 3" pipe. I'd like to go to a blow through but not sure if going from a 3" tube to a 4" mass air really makes any sense. Might cause some issues going from a 3" to a 4" section then back down to a 3". Or I could just go from 3" up to the 4" and then go straight into the throttle body and neck it down to 3" with the MAMeter right in front of the throttle body.
why don't you run a '04-newer slot style MAF and one of justin starkey's MAF adapters. that's your best and cheapest bet.
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justin mccluske- Your intake is is like the one I made for my draw thru with the L maf, and I never had a stable maf signal....I'm not sure why.
tarajerame - I agree, with the 04' slot style maf idea, some even have the iat wired through them. But, Derrick already has the BA maf, so I would give it a try.
Edit: I just remembered. The slot style maf with the iat is a problem if you want to use water/meth injection. You want the juice to hit the iat sensor, but never the maf sensor....
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Last edited by ONELOWF; 09-22-2008 at 02:09 AM.
Reason: Forgetful!
why don't you run a '04-newer slot style MAF and one of justin starkey's MAF adapters. that's your best and cheapest bet.
I'm not familiar with this..... I've had the BA2400 for a while, the tuner I'm using likes SCT equipment. I"m not sure if he would like using the slot style. I don't know how it will work with the other SCT equipment. Will that be a problem?
why don't you run a '04-newer slot style MAF and one of justin starkey's MAF adapters. that's your best and cheapest bet.
I'm thinking I may sell the BA2400 and go with this instead. I like the looks of this...
Any idea if the SCT tuners have any issues with tuning these? Guess not Since VMP is a SCT tuner and recommends it. I guess there are no issues with it matching up to 42lb injectors? Anyone know of any issues there?
I bought my Pmas from my tuner, made him happy twice!
I had ordered a tube from Justin, but my tuner said it was overkill, and would not give the best resolution, so too big electronically.
Email Justin and ask for his recomendation.
thanks to Dirty88 for the sig
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