[MCL968]

I started to do the suggested air box mod, but I just couldn't get around how that half a snorkel looked, so I thought I would take a different angle on the mod.



I purchased a set of 4 velocity stacks from a big Suzuki, and then I set about cutting the front out of the air box and replacing it with the new stacks mounted to a piece of Plexiglas. The 4 stacks are 2 1/2 diameter, so they should increase airflow substantially compared to the original box without the mods.



A big plus for me is that they look kind of cool, although you can't see them under the front cover.



I will post any changes in how it runs once I get the gear oil changed in the trans and the trunk back together.

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[flash]

thought about that way back when we first started. commented on it at the time. given the zero restriction of the "normal" mod, i doubt there will be any performance gain, but it will be interesting to see nonetheless.



definitely looks cool. might sound better too.

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[MCL968]

Well, the verdict is in. The airbox mod was a success (many thanks to Flash for the idea!). Throttle response is improved, power is improved, and it sounds great.



That snorkle may have a function, but these cars have a very throaty intake note that is totally lost in that intake system.



All in all the mod is a good idea, and the unexpected benefit is the improvement to the engine sound. Cost was under 20 bucks for the stacks on E-Bay, and some labor.



Feel free to contact me if you are planning to give it a shot.

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[flash]

was the response improved over the "normal" airbox mod, or just over the stock intake, like the normal mod is? any real measurements to dispel the naysayers? that was the biggest pain with the other mod.

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[Paul W]

[quote name='MCL968' timestamp='1384274720' post='152088']

Well, the verdict is in. The airbox mod was a success (many thanks to Flash for the idea!). Throttle response is improved, power is improved, and it sounds great.



That snorkle may have a function, but these cars have a very throaty intake note that is totally lost in that intake system.



All in all the mod is a good idea, and the unexpected benefit is the improvement to the engine sound. Cost was under 20 bucks for the stacks on E-Bay, and some labor.



Feel free to contact me if you are planning to give it a shot.

[/quote]



Can you link an ebay ad here? I would like to make the procurement!

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[flash]

i'd like to see the cold start looked into before others jump in. i was worried about that with velocity stacks, having messed with those before. i never did get around to finding out though. i know there have been a few cold start issues with the normal airbox mod, in colder climates. if this flows better, or more to the point, faster, it may make that worse. nothing comes free, and this may be a great mod, but i'd like to see some more information before recommending it without caution.



very happy to see somebody picking up this particular baton though. once the supercharger project got underway, i abandoned the velocity stack testing. as i said, i knew that there wouldn't be a big gain in power, but anticipated a bit of added throttle response, due entirely to the speed increase of the air getting to the MAF.

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[MCL968]

[quote name='Paul W' timestamp='1384279749' post='152096']



Can you link an ebay ad here? I would like to make the procurement!

[/quote]



Here's a link to a complete GSXR 1000 airbox. The plexiglas needs to be 12.75" by 3.5", hole size is 2.25". Trim off the interior edge of the stack (where the clamp goes) to improve flow. I spaced the edges of the holes 3/5" between holes 1 and 2, and holes 3 and 4, with a little more in the center for rigidity.



1/8" plexi works great because the groove in the stack is that width.



http://www.ebay.com/itm/03-04-Suzuki-GSX...9849125%26



http://www.ebay.com/itm/073-SUZUKI-GSXR1...13&vxp=mtr

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[MCL968]

I will report on the cold start issue once it starts getting cold here. As for the gains, they are anecdotal; I have no data to support the claims, but the qualitative impression is that of better response and increased sound characteristics.



Besides, this is just a first step, eventually I want one of them cool supercharger kits!

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[flash]

again, better than the normal airbox mod, or just better than stock?



in either event, no worries - it's a real pain to test, so i didn't really expect any data (lol - regardless of how much i was hoping for it)



like i said, i did expect to see some throttle response over the normal mod. just not sure at what cost. i was sure that here in socal it would be fine. not sure about pennsylvania in the winter. looking forward to seeing how it turns out.

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[az968]

So i'm all set to (finally!) do the airbox mod. Where are people finding the "trim pieces" for around the holes? I must be the last remaining 968 owner that hasn't done this.



Thanks.

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[Gotter]

IIRC, I got mine from Home Depot or Lowe's....

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[flash]

note on the ports: the ones we used in the design of the airbox mod are not trim ring for aesthetic's sake. they are there to smooth the airflow as it enters. you cannot get those at home depot. they are speaker ports with a rounded entry edge. the original source dried up, but they are still out there at other sources. again, the key is to use something with a smooth rounded entry edge, not a square one.



the mod shown above takes this idea to its ultimate step. the velocity stacks will do an even better job of getting the air in there. it may be a minimal improvement over the standard airbox mod, but an improvement is an improvement.

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[az968]

Flash, sorry for the bad terminology, I knew they were velocity stacks from your article and the threads, just couldn't connect my brain to my fingers when I was inquiring typing but your response should clarify for anyone looking at this. . Just ordered the Suzuki stacks from ebay. Next to the K&N web site.

Thanks,.

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[flash]

no worries. this particular mod has gotten a lot of publicity. when dave and i came up with the original one, after a day of testing and measuring in my garage (it was pretty cool - a few of the 968 guys were there) we then spent a couple of hours on the phone working out the placement and size. then, on the dyno, i was able to clearly show the gains. this bugged a couple of people, as they didn't think it would work. those same people still can't get their head around the idea that this was a joint venture (to some extent, actually a group project). whatever.



i always wanted to play with velocity stacks, to replace the speaker ports, but just never got around to it. i did the supercharger instead. i'm glad somebody else got to this. i'd love to see comparison runs with ports versus stacks though. i'm still curious as to whether or not further gains could be made.

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[az968]

I guess if you could find one of each mod and swap the airboxes between two cars and measure each combination of mod and car side by side, you'd have a pretty good idea of differences . You could even throw in a paper filter vs K&N and measure again, not to raise that old argument. I'm too far away to drive over but I could ship you my airbox after I get the stacks on them in a couple of weeks.

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[flash]

yup - that's how we did it, coupled with careful measurements of conditions prior to each run.



not likely i'm going back to the dyno any time soon. time consuming and costly, and i'm done. like i said, i went supercharger, and after over 3 years, and over 40 other cars successfully running it, it works so much better than any airbox mod or any other mod could hope to, that it just doesn't make sense for me to bother.

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[Spyderman]

So, I've managed to get my hands on a spare airbox, and I've ordered four 2" (1.97" inside diameter) speaker ports from a seller on ebay. I noticed in MCL968's post that he installed the Suzuki velocity stacks portruding from the front of the airbox, versus how 'Flash' mounted his speaker ports flush with the face of the airbox.



Is there any rhyme, reason, logic or gain in mounting the speaker ports further out from the airbox face, as MCL968 did with his velocity stacks?



The speaker ports I ordered look to have a good bit of distance on the tube portion aft of the rounded port edge, and I assume some of that length needs to be trimmed before gluing them into the freshly cut holes in the airbox, or would there be a benefit if they be allowed to extend from the airbox face, say by an inch or two?

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[flash]

no. velocity stacks do their work, not because of the distance, but rather because of the diminishing entry diameter. the air velocity is increased as it moves from the larger diameter to the smaller one. this may provide more air in the airbox, which would have the potential for more power. i haven't seen any tests on this yet, and question the likelihood of any measurable gains, due to the large OEM opening. still, it looks cool and it may help, so no harm no foul.



the subwoofer ports are there to smooth the square corner. some people have made the mistake of using some other item (like PVC pipe fitting, or the wrong speaker ports, and completely defeated the purpose. it may clean up the aesthetics to do that, but it does nothing for airflow, and in fact may actually create more turbulence than just having the hole. the ports only want to be as long on the inside as needed for gluing, and flush on the outside to avoid any entry turbulence.

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[Spyderman]

Great, thanks Flash...I'll trim the tube portion just enough to facilitate enough surface area for the glue to hold them in place, and place ports as flush to the front of the airbox as the reinforcing ribs allow. Curious to hear the enhanced 'growl' when all is said and done. May record the sound of the stock airbox and the modified airbox on my cell phone, using the record feature, and see if I can post the .wav files here for others.

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[Bulti]

Flash I'm finally arriving at phase #325 of my mega-overhaul, which would be the air box mod. But I suppose I let the thing alone until the NA Package arrives? Don't want to ruin a perfectly good non-efficient part :-)

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