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Old 03-01-2010, 01:06 PM   #1
GrimmSpeed
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Default GrimmSpeed Flow Bench Testing - Results!

There seems to be an on going debate whether or not it makes sense to add an aftermarket up pipe to a car that already has a catless oem up pipe(ie, All sti and 06+ wrx). we’ve cut apart the oem catless and found some pretty nasty ridges around the oem flex joint which definitely aren’t good for flow. We’ve seen dyno comparisons on nasioc but I don’t recall seeing actual flow comparisons. Over the next few days we will be running some comparison tests on the flow bench to get some hard data for you guys.


Off to build the flow bench jig for the up pipe….


CONSOLIDATED RESULTS FROM THREAD:

UP PIPE

Subaru OEM Cat'd Up Pipe at 28" - 164.7 CFM <--- BOOOO!
Subaru Gutted OEM Up Pipe at 28" - 216.1 CFM
Subaru OEM Catless Up Pipe at 28" - 244.6 CFM
Grimmspeed Up Pipe at 28" - 292.6 CFM

CFM increase of 20% or 48 CFM at 28" of water

I am honestly quite shocked by the difference between the catless oem and an aftermarket up pipe. My initial thought was that the aftermarket version would flow better but not by this much. I can only imagine what the difference is between an aftermarket and a cat'd oem.

Remember, this isnt max flow, this is just the flow at the industry standard of 28" of water...it is used for comparison, not determining max flow.

Subaru OEM Catless Up Pipe


GrimmSpeed Up Pipe




Ok here are the Cat'd OEM Up Pipe results
Subaru OEM Cat'd Up Pipe at 28" - 164.7 CFM <--- BOOOO!
CFM increase of 78% or 127.9 CFM at 28" of water vs. an aftermarket up pipe.

OEM Catted Up Pipe


Here is a graph of all three tests:




Subaru Gutted OEM Up Pipe at 28" - 216.1 CFM

I was rather shocked by this number compared to the oem catless up pipe. The oem catless is still about 30cfm more than a gutted oem.


Subaru Gutted OEM Up Pipe





CROSSPIPE

Subaru OEM Crosspipe at 28" - 230.4 CFM
Grimmspeed Crosspipe at 28" - 315.5 CFM


Subaru OEM Crosspipe




GrimmSpeed Crosspipe
CFM increase of 37% or 85.1 CFM at 28" of water vs. oem crosspipe.
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Last edited by GrimmSpeed; 12-17-2010 at 06:47 PM.
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Old 03-01-2010, 01:51 PM   #2
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Frankly there have been more stories of used uppipes that get installed that have cracked then there are stories of aftermarket ones... Not to say aftermarket ones dont, as there are for sure cheap knock-off brands out there.

Then there are all the fanbois that spew "it's OEM, it's god's greatest creation on earth." Thats fine for a stockish sized turbo, but go bigger, and a real uppipe with correctly sized piping could prove it's weight for that last few percent in power...

Ultimately, I think budget is what gets folks... It's almost 50% the cost to get a used uppipe, vs says yours.
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Old 03-01-2010, 02:03 PM   #3
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I agree that many of the OEM pipes will crack before the good aftermarket ones, of course the cheap ones could crack whenever.

The budget can get most people for sure, but we are hoping to prove that it is worth you money to upgrade!!

The aim of this thread was more for the flow rates, but quality and durability are also important and relevant here.
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Old 03-01-2010, 02:31 PM   #4
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In for the results. I have a COBB up-pipe installed now and going to a GrimmSpeed EWG, cant wait!
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Old 03-01-2010, 02:46 PM   #5
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looking forward to results.

As a side note, It would be really cool if you threw an OEM catted uppipe from 02-05 wrx's on your flowbench just for kicks and giggles while your at it. Maybe it would sway a few more people to swap uppipes.
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Old 03-01-2010, 03:00 PM   #6
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As the owner of an '07, i'm interested as well. I doubt that I need a new upipe, but very soon i'll be installing Group N engine mounts and would like to kill 2 birds w/one stone...just don't want to piss away $ though.
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Old 03-01-2010, 03:39 PM   #7
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Yeah we hear you, we want to know too! We are going to dig up a catted up pipe for fun as well, it would be a great comparison...

So bluemicamatt is on the not needed team, anyone else??
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Old 03-01-2010, 03:44 PM   #8
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in for results.. have an hks up pipe sitting on my floor looking to install it but may sell if no gains are yielded in the results.

when can we expect results?
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Old 03-01-2010, 03:51 PM   #9
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Quote:
Originally Posted by Sinister_kid View Post
in for results.. have an hks up pipe sitting on my floor looking to install it but may sell if no gains are yielded in the results.

when can we expect results?

yeah it will be interesting to see the CFM difference between the two. i'm almost done with the jig for the flow bench then we can get them up on the chopping block.

Justin
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Old 03-01-2010, 04:28 PM   #10
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Can you upload a pic of the cut OEM up-pipe?
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Old 03-01-2010, 05:22 PM   #11
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i'm also eagerly waiting for the results........im running vf43 and def goin bigger this summer so if an aftermkt uppipe makes enuf diff compared to my oem catless, then i'm certainly going to spend some $$$ and get a quality brand........
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Old 03-01-2010, 05:37 PM   #12
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There shouldnt be a debate. This has been covered and tested multiple times already, and the gains are absolutely proven.

Perrin tested it
Buscher tested it
Shiv (Vishnu) tested it years ago
I THINK Gruppe-S tested it
A couple members have tested it
There are multiple reports of people doing it and reporting faster spool and more power over the entire powerband. In fact, anyone who has ever done it, can tell you that its worth doing.


Gains are in the 7-14whp range and 12-17wtq range. Buscher claimed higher, but his claims are always a bit overinflated.


Anyone who needs convincing at this point, probably still wont believe you, or are the type that are too lazy to have bothered taking even 2 minutes to research it, as, again, its been covered, with dyno results to back it up, by multiple sources.

The oem catless up pipe is MISERABLE from a flow standpoint, the crush bend towards the bottom, the bend at the top that is essentially 2 crushed pipes welded together at an angle, the TINY diameter, the big ridge at the flange and pipe at the entrance. Its just aweful. Better than a catted up pipe, but not by nearly as much as people would like to think.

Last edited by Davenow; 03-01-2010 at 05:43 PM.
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Old 03-01-2010, 05:39 PM   #13
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interested in results
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Old 03-01-2010, 05:43 PM   #14
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Quote:
Originally Posted by WRX SEX View Post
interested in results


Spend 30 sec researching it and look at them. They are already out there and have been for years.
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Old 03-01-2010, 05:45 PM   #15
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What I would REALLY like to see is back to back dyno results with a low level modified car (stage 2, or even stock) comparing a catless up pipe to an EWG up pipe.

I say that because so many are under the mistaken impression that it only offers better boost control. When in fact, it offers very nice power gains.
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Old 03-01-2010, 05:51 PM   #16
GrimmSpeed
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Quote:
Originally Posted by Davenow View Post
There shouldnt be a debate. This has been covered and tested multiple times already, and the gains are absolutely proven.

Perrin tested it
Buscher tested it
Shiv (Vishnu) tested it years ago
I THINK Gruppe-S tested it
A couple members have tested it
There are multiple reports of people doing it and reporting faster spool and more power over the entire powerband. In fact, anyone who has ever done it, can tell you that its worth doing.


Gains are in the 7-14whp range and 12-17wtq range. Buscher claimed higher, but his claims are always a bit overinflated.


Anyone who needs convincing at this point, probably still wont believe you, or are the type that are too lazy to have bothered taking even 2 minutes to research it, as, again, its been covered, with dyno results to back it up, by multiple sources.

The oem catless up pipe is MISERABLE from a flow standpoint, the crush bend towards the bottom, the bend at the top that is essentially 2 crushed pipes welded together at an angle, the TINY diameter, the big ridge at the flange and pipe at the entrance. Its just aweful. Better than a catted up pipe, but not by nearly as much as people would like to think.
Sounds like you have been around this block a few times!! We are doing this to help out the newer subie owners who are curious and those who have not found their answers yet.

Will
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Old 03-01-2010, 06:25 PM   #17
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Quote:
Originally Posted by GrimmSpeed View Post
Sounds like you have been around this block a few times!! We are doing this to help out the newer subie owners who are curious and those who have not found their answers yet.

Will
Im interested to see the reults also, Do you guys have a flowbench in house?.

I would also like to see the results done on a stock manifold setup vs ported vs ported/hi-flow crosspipe. Oh yeah While you guys are at it lets see some results from tgv's vs tgvless.
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Old 03-01-2010, 06:26 PM   #18
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I'd believe anything above stock boost (WRX not STi) would greatly see the benefits of an aftermarket catless up pipe. I know there are plenty of WRX owners who have installed a factory STi catless up pipe for the increase in flow and power since STi take-offs can be had for pretty cheap. It would be reasonable to state that the flow results would differ on the pipe diameter and smoothness of the bend. As the guys from GrimmSpeed noted, the stock STi pipe does have ridges inside because Subaru is more worried about product cost than exhaust flow numbers. This alone is what supports aftermarket products.
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Old 03-01-2010, 06:50 PM   #19
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Quote:
Originally Posted by 2gnt2wrx View Post
Im interested to see the reults also, Do you guys have a flowbench in house?.

I would also like to see the results done on a stock manifold setup vs ported vs ported/hi-flow crosspipe. Oh yeah While you guys are at it lets see some results from tgv's vs tgvless.
Yes we do! Our plan is to Flow absolutely everything eventually, but one at a time now!
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Old 03-01-2010, 07:15 PM   #20
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Quote:
Originally Posted by oguitar View Post
Can you upload a pic of the cut OEM up-pipe?

oh man, not sure if i can found it..it was a couple years ago. i havent seen it for awhile.

Justin
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Old 03-01-2010, 07:16 PM   #21
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Quote:
Originally Posted by Davenow View Post
There shouldnt be a debate. This has been covered and tested multiple times already, and the gains are absolutely proven.

Perrin tested it
Buscher tested it
Shiv (Vishnu) tested it years ago
I THINK Gruppe-S tested it
A couple members have tested it
There are multiple reports of people doing it and reporting faster spool and more power over the entire powerband. In fact, anyone who has ever done it, can tell you that its worth doing.


Gains are in the 7-14whp range and 12-17wtq range. Buscher claimed higher, but his claims are always a bit overinflated.


Anyone who needs convincing at this point, probably still wont believe you, or are the type that are too lazy to have bothered taking even 2 minutes to research it, as, again, its been covered, with dyno results to back it up, by multiple sources.

The oem catless up pipe is MISERABLE from a flow standpoint, the crush bend towards the bottom, the bend at the top that is essentially 2 crushed pipes welded together at an angle, the TINY diameter, the big ridge at the flange and pipe at the entrance. Its just aweful. Better than a catted up pipe, but not by nearly as much as people would like to think.

mr davenow, i think you may be confused. we are doing flow bench tests, not dyno tests like these guys you are stating above.

btw - you going to sema this year(long ways off i know)?

Justin
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Old 03-01-2010, 07:17 PM   #22
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Quote:
Originally Posted by GrimmSpeed View Post
Sounds like you have been around this block a few times!! We are doing this to help out the newer subie owners who are curious and those who have not found their answers yet.

Will

Fair enough


Any chance of the back to back normal catless up pipe VS EWG on same car testing? I would be willing to give Justin a big wet smooch next time I see him for it. (nohomo)

On a serious note, the "benefits of an EWG" is VERY misunderstood and I dont think anyone has ever done any back to back testing with dyno results and driving impressions and posted about it on cars with lower mod levels. At least no one of noteworthy status (like a vendor or more well known person I mean)

You have an opportunity to sell a LOT of EWGs and make people like me who try to explain that they make power even on a STOCK car have to do a lot less of pulling our hair out in frustration.
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Old 03-01-2010, 07:17 PM   #23
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Quote:
Originally Posted by GrimmSpeed View Post
mr davenow, i think you may be confused. we are doing flow bench tests, not dyno tests like these guys you are stating above.

btw - you going to sema this year(long ways off i know).

Justin
See note above



I am planning on SEMA this year, definitely I had a bit of a 6MT thing going on this year that sucked up all of my funds (and then some)



As for the bench tests, I am interested, but a lot of people will look at it and still not get it. That and the fact that CFM gains are deceptively small. Look at how small the CFM difference on a full P&P head+cams is VS a stock head and cams, yet the HP difference is HUGE.


SINCE YOU ARE GOING TO HAVE THIS BENCH SET UP.... How about some ported vs non ported stuff testing? We all know what kinds of gains you get, but I would LOVE to see some CFM numbers.


Find yourself some dyno time man, I would LOVE to see someone with some clout (sp?) put up some dyno figures on the EWG vs IWG.
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Old 03-01-2010, 07:21 PM   #24
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I also realized I sound grumpy as hell in this thread.

Sorry about that
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Old 03-01-2010, 08:34 PM   #25
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Post #6 courtesy of DuckStu has a pic of the stock uppipe:

http://forums.nasioc.com/forums/show....php?t=1561572
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