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Online Z900-WA

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Re: Modified Airbox
Reply #30 on: June 13, 2020, 11:57:49 AM
Just thought I'd throw my 2 cents in. Recently had my bike flashed & while the ecu was out I went ahead & installed a Sprint filter & completed the airbox mod according to the directions on Ivan's website

http://www.ivansperformanceproducts.com/z900rs_airboxmod.htm

Seemed like it was worth the effort, since according to his graphs doing the mod added almost 5hp, sitting on the dyno, not to mention the intake ports seem crazy small for a near liter-bike and they're location also seems less than ideal for supplying the engine with fresh, cool or even just enough air.

Anyway, I used a 1" uni-bit with a total of 12 strategically placed holes & then used the steel mesh from the stock filter along with screws & silicon to secure everything together & prevent anything besides the additional air from entering my airbox. I can't remember if I took pics, but I'll post some soon if I did, because it turned out great!!

Took my time, did it right & it really paid off. I noticed a difference from the 1st time I took it out, especially in the mid to top-end, there's just more there now. This includes sound too, definitely more intake noise, but I swear my exhaust seems louder as well but not in a bad way. I've got akra headers & SC-Project CR-T, it's a great combo & everything was factored into the flash as well, so no worries about AFR etc.

Granted, I'm sure the Sprint filter is helping too, but honestly the main reason I decided to do the mod was after spending so much $ on the filter & then seeing how tiny the stock air intakes were, I just couldn't see it being able to let enough air in, for the high flow filter to make any difference. The Sprint's filter area is probably 4-5x the size of the intakes.

Lastly, I also did the velocity stacks as recommended, but I had to wait a few weeks for them to arrive, so I can say that from experience, that they do seem to help with the bottom-end to mid-range response a bit, without any drawbacks on the top-end. Although, I haven't noticed any negative consequences from completing the mod, period. Actually, that's not entirely true, there is one drawback... It hits the rev-limiter too darn quick now & the power-cliff around 9.5-10K isn't there anymore (after mod & flash) so it's a lot easier to hit the rev-limiter if you're out riding hard & don't keep an eye on the dahs. The worst part is, it really feels like it could keep pulling strong for another 1000 rpm or so, if the limiter weren't there, now that it isn't being suffocated...

Overall, I was really surprised & impressed by what a noticeable improvement it made to the bike. I really debated over whether to do it or not. I'm very happy I did!!

Oh yeah, it's been about a month now & I still haven't seen any trouble codes from it either


Offline Frontline

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Re: Modified Airbox
Reply #31 on: June 13, 2020, 03:49:19 PM
As someone that has been tuning for years and likes to analyze data (logged engine data), few things you need to be aware of. Don't trip over the numbers  :002:

First of all, the "Ivan airbox mod" came about because of the inferior RS airbox design (inlet). Ours is different, and just randomly adding holes to the airbox changes its velocity and not always in the way you think.

The 116HP dyno pull was done in June and the 121HP run was done in November. Ignoring that I plugged your air numbers (alt, pressure, hum, temp) in my calculator and came out to only +2.2HP difference as your actual D/A was 500FT lower in elevation with a correction HP figure of 2.2% (119hp vs 121hp). When looking for dyno run improvements, I would only compare dyno runs take on same day and hopefully within same hour. The D/A constantly changes and since an engine is nothing more than an air pump, air quality plays the biggest role (on a N/A engine). Boosted engines make their own atmosphere.

Still, the butt dyno can be pretty accurate if you know your bike pretty well and what to expect (before/after). Personally, I rather listen to that than a dyno sheet taken at two very different times. One thing I am impressed with is the dyno numbers (irrespective of final numbers) is pretty good considering you are at 1,840FT elevation with a very high 4,500FT D/A!!! On worst days we are 2,600FT and best days 900FT below sea level (when N/A motors feel like they all have nitrous  :020:

Thanks for sharing your info  :047:
Last Edit: June 13, 2020, 03:54:27 PM by Frontline

Offline KawaJagz

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Re: Modified Airbox
Reply #32 on: June 14, 2020, 09:34:19 AM
Seems like a lot of effort and expense for gains only in the top 1k rpm so no real improvement on the road, but may be better on a track.
I used to be indecisive, but now I'm not so sure!

Offline Frontline

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Re: Modified Airbox
Reply #33 on: June 14, 2020, 12:50:53 PM
*Originally Posted by KawaJagz [+]
Seems like a lot of effort and expense for gains only in the top 1k rpm so no real improvement on the road, but may be better on a track.
Maybe you don't but I take my Z900 to redline every time I ride. You ever hear the term "Rome wasn't built in a day"... On N/A engines, it takes a lot of little things to make a difference. And on the non-restricted Z900, it takes even more. So to say its not worth the effort/expense on doing 1 mod isn't looking at the big picture or is too lazy to do what it takes.

I've been very interested in taking the cylinder head off and doing a heavy port job...but it would shock people how little is to be gained with a lot of work. I would have done it long ago if the engine wasn't mechanically rpm limited.
Last Edit: June 14, 2020, 12:51:46 PM by Frontline

Online Z900-WA

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Re: Modified Airbox
Reply #34 on: June 23, 2020, 09:45:01 AM
Just wanted to give a quick update on the results of my airbox & velocity stacks mod done in conjunction with my flash.

1st off, I also installed a sprint race filter at same time. I also have a full system, SC-Project Titanium CRT w akra headers.

2nd, I too, prefer the top end of the rev range whenever I'm riding aggressively (which is 90% of the time). I had my rev-limit raised with flash. Unfort nowhere near the level that powertronic's ecu sw does (13k) or sbk's flash service does (check youtube "sbk Z900") they're out of thailand & frequently raises their z900's to 12-12.5K & show massive power gains up top as a result. Now, I can't say how legit their results are, but like I mentioned before, from my own experience after the mods & flash the massive drop in power after 9-9.5kish is gone now & it feels like it would keep on pulling if the limiter were raised to 11.5k or so.

I haven't noticed any lack in low end at all and I actually used the velocity stacks from a previous gen 2015' Z1000 that I got off ebay, brand new condition, all 4 for $19. They're approx. 1/2" longer than the short ones in our stock setup & all of equal length.

As a side note, I also just fitted my Annitori QS Pro 2 to the bike & aside from a few settings I need to dial in to perfect it & eliminate the occasional false neutrals. I'd def reco to anyone considering, Vcyclenut even has a $15 off coupon from some of his YT affiliates, so it's just over $200 & well worth it. Plus easy to install. I'm much happier with the overall performance of the bike now after these mods. I Just wish the rev-limit was higher, now that I know it can be done.

I'm gonna be resending my ecu in, in the next week or so, they forgot to disable my 02 sensor & when I do, I'll snap some pics of my setup & mods to post on here.

In the meantime, check out these articles on the impacts of modding you're airbox / velocity stack length, shape & diameter.

http://www.phaedrus.me/id158.html

http://www.phaedrus.me/id158.html

For some reason, different pages keep giving me the same link, so if you're interested just go to the page in the link, scroll to the bottom and select the links to the other pages with the various different types of tests and their results.

The results are nothing short of incredible, IMO. It's not for our bike (obviously) but I did a lot of searching & finding someone who put in this level of effort & attention to detail, experimenting with various airbox mods & velocity stack parameters / combinations & even comparing the results on multiple dynos deserves some serious respect & appreciation. This type of info is nearly impossible to find, especially with such a controlled & scientific approach to the testing including detailed analysis of all the results.

My impression of the results, is that these type of mods can make a significant difference to a motorcycles performance, both good & bad. The only way to know for sure is to try it for yourself, but your best bet is to let a pro do the experimenting for you and follow their advice if you trust their results. After plenty of research, I felt confident I could rely on Ivan's results to be genuine, he didn't really have much to gain by posting the instructions online for free, afterall I'm glad I did, but I never would have done it otherwise.

Offline MZ900

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Re: Modified Airbox
Reply #35 on: June 23, 2020, 09:51:14 PM
Would love to see the mod
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Offline RobZ900

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Re: Modified Airbox
Reply #36 on: June 23, 2020, 10:11:31 PM
*Originally Posted by MZ900 [+]
Would love to see the mod

+1. Interested to see the finished product.
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Offline MZ900

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Re: Modified Airbox
Reply #37 on: June 24, 2020, 05:50:44 AM
Watched sbk videos.... well , tacho goes to the 13k nice curves, but is it really safe? My tuner refused to remove rev limiter to keep the engine life 🤔
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Online Z900-WA

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Re: Modified Airbox
Reply #38 on: June 25, 2020, 03:58:42 AM
Really couldn't say for sure on the safety. I'd have to assume prob not, although they have done a lot of Z's @ 12k+.

However, p3 tuning out of uk raises Z900's to 11.2k w their "Woolich" flash & they're definitely a legit outfit, so I'd be more than comfortable with that. Trying to get 2WDW to make it happen for me, will def let you know if I'm successful.

There is a video on YT where a Z900 owner has a discussion about all of his mods (think that's nearly even the title btw) & says he's put 10k miles on his Z since having limiter raised to 12k w Woolich & hasn't had any issues.

Either way, with a flash & better airflow, in & out, it really does seem like it wants to keep revving... Whereas before you knew it was time to shift when the power dropped a 500-1k before redline, the dropoff isn't really there anymore, so an extra 500+ rpm would just be a nice cushion to avoid the limiter.

Can't believe I didn't take pics of the process but I'll post asap.