Raptor 350 Intake Stuff

[griff]

I pretty much finished the modified intake on my Rap', came out pretty nice I think.

Modified lid, 2" snorkel added...

This is an early pic of the v-stack I made.

Its 2.5" aluminum pipe, I used a pipe-expander to get a good press fit in the airbox throat. The carb side of the stack is radius'd to blend with the boot. Then everything burnished, and the throat wet-sanded and polished. I used Permatex Black during final assembly to bond the pipe to the airbox. Its VERY solid.

And a K&N SN-2570 conical air filter clamped on....

Already ordered an Outerwears for the filter, should be here next week. I had them make a custom one for the intake snorkel (thats why it has a flanged lip), so that I can cover it if I'm gonna be in super sloppy conditions.

Seems to flow very nicely......

 

[jasonp]

cool!

 

[griff]

cool!

Thanks

Hey, maybe you remember..... cfm formula for engine potential.

I think its:

max rpm X CI displacement / 3456 = engine cfm

 

[kreed5821]

Very nice, Griff!

 

[floridaredneck]

Nice i did the same thing with mine a while back.

 

[jasonp]

[quote:jowjl3c4]cool!

Thanks

Hey, maybe you remember..... cfm formula for engine potential.

I think its:

max rpm X CI displacement / 3456 = engine cfm[/quote:jowjl3c4]

This is the one I got.
Average air flow (CFM) = 1.67 x HP per cylinder

 

[griff]

[quote:2aoi3ezd]

Thanks

Hey, maybe you remember..... cfm formula for engine potential.

I think its:

max rpm X CI displacement / 3456 = engine cfm

This is the one I got.
Average air flow (CFM) = 1.67 x HP per cylinder[/quote:2aoi3ezd]

Thats a different one than I remember, but it looks like it works too. I think that one tries to show 'real' cfm, where the one I remember shows only the theoretical physical maximum.

A friend of mine said to just to take the lid off (rather than run an additional 2" hole). I told him I didnt see the point, its a 349cc engine, its maximum cfm isnt all that much.

So I did the math, 349cc = 21.3 CI. OK, I'll assume a 10,000rpm redline for the moment.

10,000rpm x 21.3 / 3456 = 61.6 theoretical maximum cfm

Thats the most the engine can draw at any given point. Well, a unrestricted 2" hole will flow a lot more than that by itself, and that airbox already has a decent size hole in the stock snorkel as well.

Most K&N's are good for 500+ cfm easy.

So yeah, I thinkin this setup compared to taking off the lid wouldnt even show up on a dyno for a relatively stock 350.

Youve been on a flow bench much more recently than I Jason, how much do you think an unrestricted 2" hole will flow?

 

[jasonp]

You know I'll tell you something griff. I don't even run an airbox as the conditions I run in permit me to do so. Just by trying the Uni to the K and N I can feel a little difference. I have a 50mm volecity stack on the UNI and the just a small little K and N filter that pushes on to the carb. I feel more hit at about 8500 rpm and has a little more pull with the K and N. Both setup should flow enough for the engine. My best advice is to go try it and see what you actually feel. If you feel no difference you confimed it for yourself that the hole flows enough air.
A unrestricted 2" hole will flow more then 500 cfm at 20" inches of water.

 

[griff]

You know I'll tell you something griff. I don't even run an airbox as the conditions I run in permit me to do so. Just by trying the Uni to the K and N I can feel a little difference. I have a 50mm volecity stack on the UNI and the just a small little K and N filter that pushes on to the carb. I feel more hit at about 8500 rpm and has a little more pull with the K and N. Both setup should flow enough for the engine. My best advice is to go try it and see what you actually feel. If you feel no difference you confimed it for yourself that the hole flows enough air.
A unrestricted 2" hole will flow more then 500 cfm at 20" inches of water.

500cfm, yeah thats in the range I expected, cool, thanks

Yeah, I'll definitely experiment with the lid off. I have to run a lid realistically, I just get into too much ****

With the Uni to K&N, I know they'll be a difference. Uni's dont draw air through them very cleanly, A LOT of turbulence. Even though its flow rate is above this engines requirement, that extra turbulence in the intake tract causes some velocity loss into the venturi.

I used that conical K&N instead of the cylindrical type, conicals tend to have a very nice and even flow through them, and since its a little smaller, theres more volume in the airbox outside of the filter. In theory, that helps reduce the pressure/vacuum differential when you nail the throttle.

But I dont think that will make a difference with my config, that 2" hole plus the stock hole in the lid can definitely flow a lot of air. The engine just doesnt have enough displacement to create that much of a vacuum at any given time.

Well, it'll be interesting to play with nonetheless

 

[warriorguy5]

very creative , well done . I think you should make a couple sets and sell em hahha

 

[jasonp]

[quote:iiab7zzm]You know I'll tell you something griff. I don't even run an airbox as the conditions I run in permit me to do so. Just by trying the Uni to the K and N I can feel a little difference. I have a 50mm volecity stack on the UNI and the just a small little K and N filter that pushes on to the carb. I feel more hit at about 8500 rpm and has a little more pull with the K and N. Both setup should flow enough for the engine. My best advice is to go try it and see what you actually feel. If you feel no difference you confimed it for yourself that the hole flows enough air.
A unrestricted 2" hole will flow more then 500 cfm at 20" inches of water.

500cfm, yeah thats in the range I expected, cool, thanks

Yeah, I'll definitely experiment with the lid off. I have to run a lid realistically, I just get into too much ****

With the Uni to K&N, I know they'll be a difference. Uni's dont draw air through them very cleanly, A LOT of turbulence. Even though its flow rate is above this engines requirement, that extra turbulence in the intake tract causes some velocity loss into the venturi.

I used that conical K&N instead of the cylindrical type, conicals tend to have a very nice and even flow through them, and since its a little smaller, theres more volume in the airbox outside of the filter. In theory, that helps reduce the pressure/vacuum differential when you nail the throttle.

But I dont think that will make a difference with my config, that 2" hole plus the stock hole in the lid can definitely flow a lot of air. The engine just doesnt have enough displacement to create that much of a vacuum at any given time.

Well, it'll be interesting to play with nonetheless [/quote:iiab7zzm]

I think what I'm feeling is the differences in intake length between the two filters not actual flow differences... I'm not sure though. I like to use the UNI under very dust conditions as it's a bigger filter and can take a lot more material before getting plugged up.
That would make sense about a smaller filter having less pressure differental in an airbox type setup.. I think what the total flow of the air box is something to consider but also right when you do crack the throttle open there is a huge space vaccum is trying to fill. The amount of time it takes to fill that hole is basically the restriction. I do feel as though intake and exhaust tuning play a hand and hand roll so as the overlap event on the camshaft.

 

[griff]

I think what I'm feeling is the differences in intake length between the two filters not actual flow differences... I'm not sure though.

If you arent running an airbox, or have open-lid setup then the intake tract length only really matters post air-filter. The length of the filter doesnt matter too much, as it can draw air along its entire length. Its advantage is as you noted, theres more surface area, so you increase the service interval.

That would make sense about a smaller filter having less pressure differental in an airbox type setup.. I think what the total flow of the air box is something to consider but also right when you do crack the throttle open there is a huge space vaccum is trying to fill. The amount of time it takes to fill that hole is basically the restriction.

Spot on

I do feel as though intake and exhaust tuning play a hand and hand roll so as the overlap event on the camshaft.

And again

 

[jasonp]

I have a 50mm volecity stack on the uni setup.

 

[griff]

Finally had a chance to do some more tuning and testing today. The carb was still a little lean on the main, so I now have a 155 in there, which is working well. Pulls cleanly up top now with a nice solid strong pull.

I have the a/f screw set at 2.5 turns out right now, it seems happiest there. The Holeshot needle is still on the 3rd clip.

After I was done fool'n around with that, I tested the bike with and without my modified lid. No difference at all, not even a little bit that I could notice. The additional 2" hole seems to flow more than enough, and taking the lid off doesnt even register on the ole' butt-dyno.