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Old 01-29-2009, 08:20 PM   #1
apexslider
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Default Perrin GT35 rotated with Blow thru, questions

I just picked up this kit and was told by my tuner to not use the Perrin Blow thru boost tube. they said it can have voltage variations making the tuning process more difficult, and result in sub standard tune. This sound familiar to anyone? If so, do you recommend going with a normal (for GT35) intake with big maf?
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Old 01-29-2009, 08:57 PM   #2
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I find that the blow thru is easier to tune and the reason most companies offer it for their 35r kits is because unless you can put a CAI down in the fenderwell a ways away from the inlet of the turbo you will have idle issues especialyy when you first come to a stop.A lot of higher hp cars run a blow-thru,where do you live and try to find a better tuner around you.
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Old 01-29-2009, 09:14 PM   #3
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Quote:
Originally Posted by john 1badSTI View Post
I find that the blow thru is easier to tune and the reason most companies offer it for their 35r kits is because unless you can put a CAI down in the fenderwell a ways away from the inlet of the turbo you will have idle issues especialyy when you first come to a stop.A lot of higher hp cars run a blow-thru,where do you live and try to find a better tuner around you.
And this makes sense to me. I would think you would want the maf closer to the throttle body for more accurate readings of what the motor is actually seeing.

I live in Protland, OR...and the tuner I was going to use came HIGHLY recommended
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Old 01-29-2009, 09:21 PM   #4
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If you don't mind me asking who is it? I know Tim Bailey lives somewhere out there but I am not sure where but he's pretty good.
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Old 01-29-2009, 11:42 PM   #5
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The Perrin blow-through.... blows Blow-through MAF's can work well, but the Perrin one is very inconsistent in it's readings. I run a blow-through on my own car but I'd much rather run a good big MAF in the fender instead of the Perrin blow-through.
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Old 01-30-2009, 12:11 AM   #6
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Quote:
Originally Posted by john 1badSTI View Post
If you don't mind me asking who is it? I know Tim Bailey lives somewhere out there but I am not sure where but he's pretty good.
I have talked to Tim and he will be the one tuning my car. Tim did not tell me the above personally, but Surgeline did. They said they would happily tune my car with the blow thru, but they prefer the bigger maf in the fender.


Quote:
Originally Posted by socalLGT View Post
The Perrin blow-through.... blows Blow-through MAF's can work well, but the Perrin one is very inconsistent in it's readings. I run a blow-through on my own car but I'd much rather run a good big MAF in the fender instead of the Perrin blow-through.
what big maf would you use?
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Old 02-11-2009, 03:13 PM   #7
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Based on what experience are you thinking a blow thru bigmaf is a good idea. This is an absolute house of cards solution.

I've tuned two of them and they are not only challenging to tune, you often end up with turbulence and temperature effects on the MAF sensor that are untunable.

The primary reason people like the blow thru is so then can run a BOV and vent to atmosphere, and frankly half of the BOVs leak, so the BOV before the MAF ends up leaking in cooler air that causes turbulence.

On top of this you are asking the MAF sensor to operate quickly over a range of more than 100F and it is not designed to react that quickly. Intake temps are relatively constant and change slowly. Boost temps very wildly.

If you are operating a turbo that large, speed density based systems are the way to go.
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Old 02-11-2009, 03:18 PM   #8
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Go with whatever your tuner is comfortable with.
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Old 02-11-2009, 03:24 PM   #9
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Ditch the perrin blow through.. on a gt35r setup its going to be a PITA to tune.
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Old 02-11-2009, 03:38 PM   #10
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Quote:
Originally Posted by Badazzcr View Post
Ditch the perrin blow through.. on a gt35r setup its going to be a PITA to tune.
I did. I went with a big MAF in the CAI. But I'm going speed density once my tuner has it available for my car.

I should have my tune/dyno results monday evenning
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Old 02-11-2009, 03:42 PM   #11
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i dont know man, i know 2 GT35R STi's that have a perrin blow thru setup and there cars runs fine. One of the owners of the GT35r sti tunes the car himself, and he say's it really wasnt that hard, he also tuned the other blow thru gt35r STI as well. I've rode in one of them and it seems so smooth.
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Old 02-11-2009, 03:51 PM   #12
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Quote:
Originally Posted by TopEndPull View Post
i dont know man, i know 2 GT35R STi's that have a perrin blow thru setup and there cars runs fine. One of the owners of the GT35r sti tunes the car himself, and he say's it really wasnt that hard, he also tuned the other blow thru gt35r STI as well. I've rode in one of them and it seems so smooth.
the issue for me, was the tuner said it would cost more in dyno time to get the blow thru tuned, making it not worth it to me. My tuner said he would tune it, I just didn't want to pay for it
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Old 02-11-2009, 03:58 PM   #13
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I see, yea he did mention that it did take much longer to tune. but it was all road tune, i can see where your getting at.
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Old 02-27-2009, 09:48 PM   #14
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So from what I understand:

Big MAF CAI > Perrin Blow through pipe

A few tuners in my area are also steering me away from the blow through pipe.
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Old 02-27-2009, 09:50 PM   #15
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By the way, isnt this thread posted in the wrong section??

I think it supposed to be in the Engine management/Tuning section.
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Old 02-27-2009, 11:31 PM   #16
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The problem I think Surgeline is referring to is the turbulance a blow through can cause.. Tim Bailey has tuned my car several times and each time I would try to inprove on my custom blow through setup. The last one I came up with was pretty solid, but speed density worked out much better. Blow through's can become unstable if the slightest bit of turbulant air crosses the MAF. You'll be doing a pull through the rev's and then "BAM" a lean spot occurs.. On the next pull it's not there.. I can totally understand why it would be time consuming to work with that..
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Old 02-28-2009, 06:04 PM   #17
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I've been hearing ALOT about Subies going "speed density" lately. Are there kits available now for our cars? Cobb is supposedly releasing maps for speed density pretty soon.
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