MIGHTYMOUSE

iTrader: (59)

thinking about changing my setup to blow through.

draw through:
no oil possible on the maf
can't blow it apart

blow through:
more accurate air temperature
faster fueling response

thoughts?

Ryan23silverado

iTrader: (1)

I have a draw through setup with my Whipple twin screw. I am just thinking here, but wouldn't the hotter air temps on the blow through setup make it a leaner condition? Hotter IATs means a less dense incoming air charge to the computer, so the computer wouldn't put in as much fuel...? This could be bad on a SC setup.

XLR8NSS

iTrader: (4)

Couldn't you put the air temp sensor anywhere with either setup. I don't see how it would be more accurate on a blow through setup unless the sensor is integrated into your MAF? Do you have a MAF where it is? If you do you could still get a regular sensor and put it anywhere.

I've had both setups and I think the pull through was nicer for one reason. There was no unmetered air from the PCV setup like with the blow through. My MAFT didn't seem to work at all with the constant PCV leak with the blow through method.

I did hit something in the road one morning though and it pulled a piece of rubber tubing apart after the MAF. Since I was running the pull through setup at the time the car went extremely rich and died. It did start back up and drove fine after a few seconds though even with the tube ripped apart.(I didn't know it was like that until later)

Both methods have the pros and cons so I think if one is working for you then stick with it.

John

Mike Morgan

On our Corvette Supercharge kit we opted to set it up for draw through for several reasons.
1. More stable readings from MAF
2. Closed bypass system. It's quieter and stabalizes the inlet pressure
3. Closed PCV system and no oil through MAF

On cars with integrated IAT sensor, we've added a seperate sensor to meter inlet temps just before the throttle body. Earlier C5's already have a seperate IAT sensor.

The only realy drawback to draw through would be a flow limitation of the meter, but if you use the larger MAF there is more than enough flow.

red ws6 99

Blow through -

1.You can get the maf as close as possible to the engine. Which means its quicker responding to change. On FI this is of big concern.

2. PCV is not concern if its setup properly

Draw through -

1. Possibility of slightly more accurate reading due to less turbulent flow. With proper ductwork and MAF setup little to no difference from blow through.

Gary

Black LS1 T/A

I've done it both ways.

The Draw-Thru position was the most enjoyable (idled better) and I was able to dial LTFT's in better... easier to tune.

On the other hand, I saw a couple pounds less boost than with push-thru, and the MAf flaked out for a while when I took it thru one of those car washes with spray hitting the underside. I'm definitely uncomfortable with it down there,

But, it idles so sweet and tunes so much easier down there.

Maybe when I up the boost I'll put it back. I may even try to shield the MAF from the elements with something.

Black LS1 T/A

Hey, Mike M -

What's the word with your larger crank pulley?

Did it work ok...? do you have more, yet?

Black LS1 T/A

Mike, are your crank pulleys selling like hot-cakes why they are not available, or is it not quite a priority to have a couple always in stock?

I have a 2.80" Reichard Racing "no-slip" pulley and wondered what you thought the boost level might be with it with your crank pulley? I also have the 3.20" and the 4.10" ATI pulley.

I know what you estimated for the 4.10" pulley: 10 to 12 psi. What do you think the 3.20" might produce with your crank pulley?

Thanks, man!

Mike Morgan

Actually it's been a high priority for myself, but it's been a real hassle with the machinist. I should have about 10-15 in stock once I fill the orders. They have one more machine operation left and should be done tomorrow. I need to get them hard anodized and should be ready to ship. We'll start shipping friday or monday and might take a couple days to ship them all out.

Believe me this has been more work and time on my end than you could imagine. The idea is for me to make money for as little time as possible , but that never seems to happen. Oh well, it's a good part.

Mike Morgan

The 2.8" will over spin the blower. A 3.4" is the smallest I would recommend with a max RPM of about 6500rpm limit.
Are we talking on a 422CI motor? A 3.4" pulley will probably make about 12-14psi of boost if there is no slip. That's a rough estimate. It's hard to make a lot of boost on a D1 with a big motor. The blower has to work pretty hard to keep up with the engines needs.

ChrisB

The MAF itself is inherently temperature compensated - so the temperature of the air (within reason) will not skew the massflow readings.

It's much more effecient from an airflow standards to push the compressed air through the maf than to try to suck through.. and the timing/air temp changed come from the IAT.

Also with a draw through you have to vent your bov back into the pre-compressor area - with a blow through you can vent to atmopshere.

There a pro's and con's to either method - I personally have had better luck with blow-thru setups, and performance wise I think they are better.

Black LS1 T/A

I understand.

I think it's a great product, too... if I can get my hands on one.

We appreciate the effort you went to to design it.

Black LS1 T/A

Thanks. I want about 12 PSI max.

I'm seeing 8 PSI immediate, 10 PSI at about 6200 and close to 11 at 7000 now with the ATI crank pulley and 2.80. I want to settle at 12 PSI final at about 6500 to 6800 RPMs. Do you think your crank pulley and my 4.10 will make it?

I guess I can just try it. It's not like I haven't changed the pulley over and over again.

Mike Morgan

We just from a mathematical stand point a 3.75" pulley would be the same as the 2.8 you run now. I would run either a 3.6" or 3.5" pulley.

AzzHauler

iTrader: (3)

Oooh! Thanks for the update Mike. Sounds good, I can't wait. Seems like new products just don't like getting out fast, I think Rob knows this all too well now also.

MIGHTYMOUSE

iTrader: (59)

hey look at this post, well so far i am still suck through, but i do have my bov venting to atmosphere without issue... and now that i have the metal maf back in the car i should be able to move it without fear of blowing it apart like the plastic one.. casey we need to work on this AFTER friday night

AzzHauler

iTrader: (3)

No problem, only I'm working this weekend.

02BlackWS6

So if I'm reading this right, the pull through setup idles better and has less surging? If I install the MAF before the blower I might get a Pace 85mm descreened MAF. This way there's little to no restriction, and I'll cap the BOV connector on the intake hat and install a little filter on the BOV. Plus this setup sounds like my MAFT will still be of some use.

Black LS1 T/A

The better idling is cool and all. But, the most important thing to me is that LTFT's are at least 10% more positive when in the blow-thru position with the ATI. It's been theorized that the way they route the inlet hat hose to the throttle body makes the car see a vacuum leak. So LTFT's rise.

This makes you have to lower the Injector Flow Rate table so low, that with larger injectors, you run too rich to be able to get a good PE/RPM table adjustment. I had to go into the dreaded MAF table to compensate where PE/RPM table values weren't stupid low.

With the stock MAF, there is more restriction. But, tuning is a LOT easier.