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Old 02-16-2010, 01:30 AM   #51
NSFW
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Quote:
Originally Posted by CoolRex View Post
Blow thru was very inconsistant on my car. Draw thru not only made more power but stayed consistant.
Did your car still have the PCV valve installed when you ran blow-through?
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Old 02-16-2010, 06:44 AM   #52
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Nope.
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Old 02-16-2010, 06:56 PM   #53
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what goes on the end of the tube? short ram, cai, or just a filter?
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Old 02-22-2010, 11:59 PM   #54
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Edit= Extremely bad values, my Latency was way off!! Do not use for anything other than mockery

Quote:
Originally Posted by NSFW View Post
Cool, good to know. I have some questions, if you don't mind...
What turbo?
What diameter is the tubing at the MAF sensor?
How many grams per second is your MAF reading? And how many volts?

I'm trying to figure whether I need 3" or 3.5" tubing.

Thanks!
For contrast: I have 86mm maf tube so here are my numbers:
FPred


But really only pay attention to up to 2.2v, I haven't finished scaling open loop, it is pig rich, like richer than 10:1 when it should be 11.5:1 on my table.


Code:
MAFv	G/sec
0.9375	0.423
0.9766	0.743
1.0156	1.00623
1.0547	1.62752
1.09375	2.02662
1.1328	2.52565
1.1719	2.95892
1.2109	3.35982
1.25	3.68061
1.28906	4.07908
1.32812	5.25466
1.36719	5.63185
1.40625	5.93841
1.4844	8.65653
1.5625	11.2902
1.64062	14.7685
1.71878	18.4448
1.7969	21.9734
1.875	26.9944
1.9531	30.59
2.03125	36.4375
2.10938	41.5196
2.1875	47.272
2.26562	55.8115
2.34375	69.0561
2.42188	75.5043
2.5391	83.823
2.65625	85.1789
2.7734	123.809
2.8906	142.262
3.0078	162.165
3.125	183.682
3.2422	207.029
3.3594	232.37
3.4766	259.896
3.59375	266.404
3.7109	281.96
3.8281	290.674
3.9453	328.79
4.0625	371.707

Last edited by Bizko1288; 10-16-2010 at 11:29 AM.
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Old 03-20-2010, 03:36 AM   #55
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Really obvious question I'm not sure about anymore because no one has mentioned it as a problem: Isn't capping the PCV side that vents while on boost just a really bad idea for engine longevity?
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Old 03-20-2010, 11:09 PM   #56
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The crankcase port typically isn't capped, it's routed to a catch can or air/oil separator.

The key thing is to cap the nipple on the intake manifold.
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Old 03-21-2010, 12:20 AM   #57
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Quote:
Originally Posted by NSFW View Post
The crankcase port typically isn't capped, it's routed to a catch can or air/oil separator.

The key thing is to cap the nipple on the intake manifold.
I must be misunderstanding something then.
Can I trouble you to critique these points please (assuming MAF in intercooler pipe)?
I thought the hose between the pcv and turbo inlet pipe would need to be capped so metered air is not cycling past the pistons and back to the inlet tube while system is in boost.
I also thought pcv to intake manifold could remain stock as this off-boost venting does not interfere with MAF accuracy.
Lastly, what about the head breathers, would those perhaps be tied into the pre-PCV crank vent hose so they too do not vent metered air to the inlet?

Noob here .

TIA!
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Old 03-21-2010, 02:03 PM   #58
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Quote:
Originally Posted by climberd View Post
I thought the hose between the pcv and turbo inlet pipe would need to be capped so metered air is not cycling past the pistons and back to the inlet tube while system is in boost.
It's typically retained, but with catch-cans / air-oil separator in the middle.

With draw-through or blow-through, that air won't affect MAF readings.

Quote:
I also thought pcv to intake manifold could remain stock as this off-boost venting does not interfere with MAF accuracy.
Off boost, the intake manifold is in vacuum, so that hose pulls air in. With the stock MAF location, that's just fine. With blow-through, it's a source of unmetered air.

Quote:
Lastly, what about the head breathers, would those perhaps be tied into the pre-PCV crank vent hose so they too do not vent metered air to the inlet?
Head breathers get treated the same as the case breather - into a can-can/separator, and then into the turbo inlet.
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Old 03-21-2010, 02:44 PM   #59
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Default noob question - rough idle

So at idle, my 07 STi dips and almost/does stall. I have the perrin gt30r setup with blow thru and fmic. After reading through this post, it seems I may have problems relating to this. My tuner said I have a leak somewhere and I have to find it before he can tune for me. It makes me want to sell the car

I appreciate any suggestions of course
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Old 03-21-2010, 04:38 PM   #60
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Well, is there a hose running from your PCV valve to the intake manifold, or not?
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Old 03-21-2010, 05:36 PM   #61
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I dont know what it looks like. I tried to look up a diagram so I can check, but I'm not finding anything online. Once I find something I will be able to answer that question.
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Old 03-21-2010, 06:17 PM   #62
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Ok I found it. Yes it does still have a hose connected that looks like it runs down to the top of the block.
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Old 05-21-2010, 05:36 AM   #63
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So did you try removing the PCV valve?
With a blow-through setup, it becomes a vacuum leak.
It's what your tuner was complaining about - it'll screw with your AFRs for sure.
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Old 06-29-2010, 06:49 PM   #64
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So, whats the conclusion? I'm thinking about Perrin blow through tube. To buy or not to buy?
Because I found lot of different info.. For example:

http://forums.nasioc.com/forums/show...&postcount=586
http://forums.nasioc.com/forums/show...&postcount=591

Perrin FMIC kit on the way, so I'm thinking about this tube... Would be easier to make some custom turbo inlet without MAF for my rotated setup...

Who using these? What's your experience?
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Old 06-29-2010, 10:11 PM   #65
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Quote:
Originally Posted by xennon View Post
So, whats the conclusion? I'm thinking about Perrin blow through tube. To buy or not to buy?
Because I found lot of different info.. For example:

http://forums.nasioc.com/forums/show...&postcount=586
http://forums.nasioc.com/forums/show...&postcount=591

Perrin FMIC kit on the way, so I'm thinking about this tube... Would be easier to make some custom turbo inlet without MAF for my rotated setup...

Who using these? What's your experience?
I'm using the Perrin FMIC and blow-through and it works great for me.
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Old 07-06-2010, 02:07 PM   #66
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BUMP for finally finding a thread that answered my questions...(did alot of searching).

And the other links too @xennon
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Old 07-27-2010, 11:36 PM   #67
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So a desk guy at the tuner told me they don't like the blow thru boost tube. But i decided to order the grimmspeed air/oil separator to keep my piping from getting oiled and ordered the blow through tube anyway. It is a band aid because i can't find a pesky boost leak. Perhaps this will eliminate my rich condition at high boost and just make my turbo work harder? What do you think? (I know i have to get it retuned for)
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Old 10-14-2010, 11:12 PM   #68
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Quote:
Originally Posted by autowagon View Post
So a desk guy at the tuner told me they don't like the blow thru boost tube. But i decided to order the grimmspeed air/oil separator to keep my piping from getting oiled and ordered the blow through tube anyway. It is a band aid because i can't find a pesky boost leak. Perhaps this will eliminate my rich condition at high boost and just make my turbo work harder? What do you think? (I know i have to get it retuned for)
I would suspect your boost leek is somewhere other than the intercooler piping before where you would put the MAF. So, no I wouldn't advice this; switching to a blow thru would only accentuate your problem and frustrate you and your tuner.

However, since your post was months ago, what results did you get?
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Old 11-08-2010, 10:24 PM   #69
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You would think after 1 year my blow-thru MAF setup would need to be cleaned? Well I decided to run the ROMRaider MAF Calibration tool to determine if it was up to par. This was done with a fresh ECU reset and then 10 minutes of city driving and 10 minutes on cruise control doing 60 mph.

Looks great to me.

Last edited by chuckdez; 11-08-2010 at 10:34 PM.
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Old 11-08-2010, 11:43 PM   #70
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Nice.
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Old 11-08-2010, 11:56 PM   #71
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someone was asking about the downsides of a blow through maf.

one downside that is somewhat annoying is water collecting in intercooler piping. (I have a blow through with a FMIC) With temp changes throughout a day, water condenses in the ic piping. Saturday it was 80*F, but that night it was in the high 40's. when you start it up in the morning, water will start hitting the maf and causing voltage spikes. this causes a rough idle. you will need to periodically clean out your ic piping.

or, better yet, just get a catch can. <-------- i need one of those.
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Old 11-09-2010, 06:51 AM   #72
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I've been running Blow-thru close to a year now so though I'd throw in my experiences:

The good:
For the most part, the car runs smoother than with draw-thru. Had just about no problems. Tuning fueling was much easier as there was no rich dips that come with a fmic and I could dial in the maf table better. No problems with running a bov and overall I'd say I'm a happy camper.

The Bad:
The maf does read higher voltages than with draw-thru so I had to get a bigger maf housing to compensate. I'm reading 4.7V on a 3" tube at 20psi with a vf39. So once in a while on a cold morning if I romp on it, I get a cell from getting too high of a voltage on the maf.
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Old 11-09-2010, 05:55 PM   #73
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Quote:
Originally Posted by Bad Noodle View Post
I've been running Blow-thru close to a year now so though I'd throw in my experiences:

The good:
For the most part, the car runs smoother than with draw-thru. Had just about no problems. Tuning fueling was much easier as there was no rich dips that come with a fmic and I could dial in the maf table better. No problems with running a bov and overall I'd say I'm a happy camper.

The Bad:
The maf does read higher voltages than with draw-thru so I had to get a bigger maf housing to compensate. I'm reading 4.7V on a 3" tube at 20psi with a vf39. So once in a while on a cold morning if I romp on it, I get a cell from getting too high of a voltage on the maf.
I'm running the Perrin blow-thru tube and with my calibrations its good for 495 grams/rev. Perrin claims their product can support 550WHP.

With my FMIC and VF39 I'm hitting 20PSI @ 3200 RPM with a 3.55 load. I can't wait for a larger turbo.
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Old 11-09-2010, 10:36 PM   #74
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What is the inner diameter of Perrin's blow-thru tube?

I'm trying to make up my mind about how big to make mine.
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Old 11-10-2010, 05:52 PM   #75
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Quote:
Originally Posted by NSFW View Post
What is the inner diameter of Perrin's blow-thru tube?

I'm trying to make up my mind about how big to make mine.
It is a little bit over 3", seems like 3 1/8" inner-diameter.
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