Technical question

[Zalama]

5 seems bit much, maybe 2-3 max..

[Jbat]

I could see 5 out of an exhaust, maybe not at peak but in the midrange you can often get large gains. like I said, dyno before and after and you will know for sure

@Zalama, not sure on that dyno sheet but those numbers are super close, your talking 1/2hp, what intake (if any) was on before the VBAK, and my guess would lean to tuning at this point. If it wasn't changed after the VBAK was installed you are limiting the motor on what it can do.

[Zalama]

The intake was stock all the way.. air filter, stock.. tubes, stock..
Of course not anymore. One of the techs said, that the air tubes in vbak are too small, and
therefore limit the air intake... I dont know, they seem pretty big in diameter for me..

[Rapomcar]

Zalama your dyno results are diametrically opposed to general wisdom displayed in this thread and other areas of this forum. You cannot argue with these numbers. I could never get my head around the rather large HP gain postulated by the simple mod of the vbak. Let us just look at the rear velocity stack and filter. It is wedged in between the frame well and tank with very little air movement. My faith in the old under tank air box is still alive and strong. I am going to keep the stock setup and attempt to rely on the beleaguered right side air filter for increased air.


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[Zalama]

I have thought about that... its a cramped space, only if I could get more air into that area
without some major bodywork.
I KNOW!!! WHEN IN DOUBT, USE NOS!!!!

[scawein]

I have tried increasing the air going in by several ways. See this thread.

DIY Cold Air Intake

I tried, I tried and tried. The airbox was built to be as large as the interior area would allow. I still have that airbox and would send it someone to try if you want to prove it to yourself.

The PR velocity stacks or Churchkey's setup offer the best air you can get in without forcing it....like you said Zalama (NOS or ???)

Unless you increase the amount of air going in, nothing you do on the output will be giving you what it can. The stock airbox is restrictive as he// and you would still be limited to the oval opening for the right side air filter.

Get more air in, get more out....I was willing to try and noticed a very real increase when I put the velocity stacks on without the airbox. I spent a lot of time making the airbox, it was a fun experiment but did NOT help.

[yamaweezle]

Originally Posted by IslamDiab

I also would like to share that i just got an email from cobra exhausts confirming that the exhaust gives 5hp

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I would believe "up to" 5hp, with the right tuning.

[Jbat]

here are my dyno sheets with samsons, churchkey vbak, and PCIII. Now have Speedstar, Churchkey Vbak, and PCV with autotune. Hope to get it dynoed with this setup before doing the H/C pistons to see what increase I get but if not the next sheet will have H/C pistons in.

[Zalama]

Originally Posted by scawein

I have tried increasing the air going in by several ways. See this thread.

DIY Cold Air Intake

I tried, I tried and tried. The airbox was built to be as large as the interior area would allow. I still have that airbox and would send it someone to try if you want to prove it to yourself.

The PR velocity stacks or Churchkey's setup offer the best air you can get in without forcing it....like you said Zalama (NOS or ???)

Unless you increase the amount of air going in, nothing you do on the output will be giving you what it can. The stock airbox is restrictive as he// and you would still be limited to the oval opening for the right side air filter.

Get more air in, get more out....I was willing to try and noticed a very real increase when I put the velocity stacks on without the airbox. I spent a lot of time making the airbox, it was a fun experiment but did NOT help.

I got interested about those intlet thingys. As you stated, that the box didnt work. How about losing the box, but staying with the inlet's. That way when riding there would be some ammount of fresh air increase near the engine air intake area..

[scawein]

Originally Posted by Zalama

I got interested about those intlet thingys. As you stated, that the box didnt work. How about losing the box, but staying with the inlet's. That way when riding there would be some ammount of fresh air increase near the engine air intake area..

You are looking for a RAMair effect, which is really hard to be consistent enough to rely on
.
My right side scoop (DIY) uses the 90 degree elbow that goes from the right side stock filter into the airbox. The way I installed it, it forces the air between the cylinders. I don't think I get much until speed but it does give me a bit of fresh air in there.



(Note: white things are vacuum line connections and you can see the 90 degree bend heading in between the cylinders.