Some questions about tb and maf location

[zblackbeast]

So, i was reading this thread (http://www.shoforum.com/showthread.php?t=57368&highlight=pre+blower+throttle+body) and i understand about 90% of it.. But now, i was talking with a friend about running the tb PRE blower on both a sc and turbo set up and he brought up something i couldnt answer. Wouldn't running the tb pre blower cause vacuum in the blower? What exactly are the benefits to running the tb pre blower?

 

[BlackonBlack89]

Sho nut blower car is like this. I forget all reasons why but I think it was easy or more consitent tuning. The maf is never pressurized. Also I would think throttle response would be better. also the blower doesn't care if its in vacuum or have air forced in it. Ie twin charged cars. Turbo usually feed pd blowers like in cobalt ss or in cobras. Also a lot of diesels have sequantial turbos small one feeding a bigger turbo for wider tq bands

Ive never seen a turbo have a tb before it. Also if I'm thinking this thru correctly u wouldn't need a bov because no air is getting in to be pressurized hence no stacking against the tb plate. But then again pd blower do have bypass vavles now

 

[NEp8ntballer]

what are the benefits to reinventing the wheel?

 

[WSC-SHO]

It was me asking questions. I was simply asking what the most efficient method for placement of the throttle body and Maf sensor's were on a turbocharged car. Wouldn't getting rid of the Maf and running a Map system be even more beneficial?

 

[Toolman]

Stock TB location, blow-through MAF (one designed to be used as a blow through, not the stock FORD stuff), is the setup for a street driven turbo SHO, IMO.

 

[WSC-SHO]

What MAF did you use then? I'm just trying to learn all I can before I attempt my turbo build this winter. (bear with me on the stupid questions )

 

[yamahaSHO]

If only you guys had someone local that knew anything about boosting SHO's...

 

[WSC-SHO]

If only you guys had someone local that knew anything about boosting SHO's...

When are you free? I've literally got like a full page of questions written down. I get off work and read up on things in my free time... :wave:

 

[Toolman]

It is an HPX slot style maf, good for metering upwards of 1000hp. Even the Ford 90mm will run out of resolution around 500whp.

You can use it in 2.5''-4'' tube. I have the 3'' housing, but you can also get a bung that will weld onto your IC piping.

While I vented metered air for many years (while using a drawthrough setup), it is not ideal. With the BTM, there is no issue with an atmospheric dump valve, your plumbing is easier (because you do not need to have the small to large to small tubing that you see on so many FI SHO's due to the size of the 80/90mm MAFs), and your tuning will be easier.

You can get an 05 mustang slot style maf for around $150, and it is good for a low boost SHO (300whp in a 3'' tube, which is the size of the TB, and makes for a nice and tidy setup), unless you want to use LARGE IC piping (3.5'' will meter up to 400whp, 4'' up to 500whp). Mine is the VMP HPX, which has about twice the resolution of the mustang maf, and is good for 600+whp in a 3'' tube, and 1000+ in a 4'' tube. It only cost $199 right now, but you need a bung and a wiring pigtail, which will bring total cost to around $280 or so. Still a great deal, considering how important proper metering of air is for a FI SHO.

 

[somedude_001]

I ran a lincoln continental maf in my turbo SHO initially and it ran great. Then I changed to a lightning maf and it was more difficult to deal with in a blow through setup because the plastic housing kept flexing when I would try and clamp it tightly and the massive size difference/packaging issues I had.

2.5" pipe to 4" back to 3". everything had to be "just so" for the car to run right if I had anything apart. I will be giving one of the maf's toolman mentioned a try in my camaro project in 3" pipe. The camaro will be a blow through setup with a atmosphere dump just like my turbo ATX had.

 

[WSC-SHO]

The idea was tossed out earlier to run the MAF before the turbo inlet and run a recirculating valve back the to the turbo, rather than venting to atmo. Thoughts?

 

[yamahaSHO]

That's one of the better options.

With my particular setup, the issue is more with the placement of the BOV/Bypass valve location in my setup. It creates weird turbulance in the piping before it gets to the MAF. I have the lowest spring that HKS makes for my BPV and it won't vent until 13 -14 PSI when it should vent around 6 with it cranked down like I have it (wouldn't vent at idle with the spring it came with - stiffest). It is unable to completely vent all the air it needs to. When I use the BPV as a "pop-off" valve to limit boost, the venting gives weird MAF readings and then my injectors go haywire. I use less injector when I do NOT vent and just run through full boost. I used to run the MAF pre-blower and vent the BPV back to the inlet of the blower. It worked great for WOT and light throttle/low RPM, but because it could not vent enough air, it would run extremely rich under engine decel. If at 5k RPM engine decel, the computer would quit adjusting and applying KAMRF and the car would have to be restarted.

If I were to purchase one of the MAF's Tim has suggested, I'm farily certain it would still act the same if I didn't address the BPV. I would like to to use a wastegate to vent/control boost, however, I would have to ideally run the WG closer to the throttle body, move the MAF and vent back before the blower. I don't have the desire to do so anymore, so I'm happy with what I've got.

If you want to chat, just contact me.

 

[Toolman]

Lots of work/plumbing/leak potential. Besides the fact that you are putting your MAF many feet upstream of the TB. The MAF is telling the engine how much air it is ingesting. But when all that air has to go through a turbo, then piping, then an intercooler, then more piping before finally reaching the engine, your MAF reading and what the engine is ingesting may not always be in sync. With the MAF closer to the TB, there is quicker/more accurate response, along with all the other attributes I mentioned above.

For the money, a proper BTM is the way to go. You will spend more in funky silicone transition hoses to make a large 80/90mm MAF work with your IC tubing than the cost difference between that 80/90mm MAF and a proper BTM.

 

[WSC-SHO]

Seems to be some differing opinions here... for the record, I'm shooting for 325-350whp, so not a crazy amount of boost. Most people I see run the TB in the stock location and the MAF somewhere in the charge piping. Is this honestly a bad setup with a MAF like toolman suggested?

 

[yamahaSHO]

Lots of work/plumbing/leak potential. Besides the fact that you are putting your MAF many feet upstream of the TB. The MAF is telling the engine how much air it is ingesting. But when all that air has to go through a turbo, then piping, then an intercooler, then more piping before finally reaching the engine, your MAF reading and what the engine is ingesting may not always be in sync. With the MAF closer to the TB, there is quicker/more accurate response, along with all the other attributes I mentioned above.

This shouldn't be a problem with tuning.

For the money, a proper BTM is the way to go. You will spend more in funky silicone transition hoses to make a large 80/90mm MAF work with your IC tubing than the cost difference between that 80/90mm MAF and a proper BTM.

My Lightning MAF and transition hoses was less than $100.

There are many ways this can be done properly. A big advantage to the slot-style MAF is being able to get great resolution and higher metering capability in a smaller diameter housing. In many cases, it gets rid of the **** larger point-style MAF's have.

At 325-350 whp, you can run with a lightning 80mm if you want to stay cheap. Personally, I would run it as a DT setup with venting boost back into the turbo inlet.

 

[WSC-SHO]

A big advantage to the slot-style MAF is being able to get great resolution and higher metering capability in a smaller diameter housing. In many cases, it gets rid of the **** larger point-style MAF's have.

At 325-350 whp, you can run with a lightning 80mm if you want to stay cheap. Personally, I would run it as a DT setup with venting boost back into the turbo inlet.

Could you explain what you mean by resolution and metering capability? Is that just how accurate the MAF actually is and how much it flows? And would I be able to step up to 375 or 400whp and still retain the Lightning MAF? What do you mean by the "****" in larger point style MAF's?

Also, what is a "DT Setup"

 

[yamahaSHO]

Could you explain what you mean by resolution and metering capability? Is that just how accurate the MAF actually is and how much it flows? And would I be able to step up to 375 or 400whp and still retain the Lightning MAF? What do you mean by the "****" in larger point style MAF's?

Also, what is a "DT Setup"

Resolution - How accurately the MAF can meter through its entire range.

Metering capability - Max amount of airflow it can measure.

Currenty hitting 5v (max) on my 80mm MAF at 440whp (last dyno), but a turbo will not have to account for the same parasitic draw.

DT - Draw-Thru
BT- Blow-Thru

**** - Look at pictures of my setup and you'll see what I'm talking about.

You'll be surprised at what 325-350whp would run like with a turbo (with great mid-range torque). I sometimes had more fun when I actually had traction.

 

[WSC-SHO]

That's the idea, looking at starting at 300-325whp with ability to tune more boost later. I'm looking at a T3/4 hybrid, 62-1 trim and with a 62-70 ar, it should support anywhere from 300-450whp while maintaining efficiency. So based on that, you think a lightning MAF would work for me?

 

[yamahaSHO]

Yes. If you're on stock pistons, I'd shoot for the 325whp range. Other than that, watch for broken axles and transmissions.

 

[WSC-SHO]

Thanks for the help, I'm sure I'll have more questions, but I need sleep tonight. I'll leave the thread up as a general question/answer thread.