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Discussion Starter #1 (Edited)
......be HAPPY with it!!!


Take a look at this. This is a comparison photo of the Akrapovic FULL race system side by side with the stock headers.

The head tube diameter is the same size and so is the basic design.

It is true the stock head pipes have flow reducing Catalytic Converters inside but if you look closely you will see this area of the stock pipe is much larger in diameter then the equivalent part of the Akra pipe to make up for the flow reduction.

Based on that one can assume the stock headpipes even with the cats inside probably flow as much as the Akra, or very close to it.
 

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Discussion Starter #2 (Edited)
Now its true the Akra system does have the H cross over tube lacking on the stock headers, BUT that cross over H tube is NOT nearly as large as the external diameter would indicate. The passage thru there is actually smaller than your little finger, so I can't even guess how much that actually helps and if it does what it does.

*UPDATE"

Actually the passage thru the H tube is about the size of a pencil. I would like to know more about how much affect this H tube actually has.

Anybody got any info on H tubes? None of the other makers Leo Vince, KR Tuned have this. I emailed Akra but I figure they are laughing at me thinking I thought they might tell me and I don't expect a response.

Im thinking it may be more of a brace than anything, but there is a passage drilled into each collector about the size of a pencil so the outer diameter size of the tube is misleading.

I can't see what such a small passage would do when such a large volume of exhaust is flowing thru the collectors when you are at full tilt boogie.

I will email Kerry Bryant at Area P and see if he will tell me.

JJ
 

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Discussion Starter #3
The final 2 pix shows that the cross over tubes on the stock headers are completely phony. You can see the holes in the bottom of them. My guess is the holes are there to prevent pressure building up inside them when they are welded on and are nothing more than "prettier" braces than what came on the 06-07 pipes.
 

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Discussion Starter #5 (Edited)
We already know by looking, the Boom Box does not have any bottle necks or mechanical restrictions to exhaust flow, but I cannot say for a fact it doesn't reduce or "muddy" up the exhaust flow thru resonance. My guess is if some, not much.

Bottom line, In My Opinion, if you have a slip on, especially one that eliminates the Boom Box, (ala Racefit, AREA P, Akra with link pipe) most likely it will flow almost as good as the Akra full system, probably very close.

I could take Akras HP readings from their website showing what the Slip On with link pipe gains as compared to Akras full system gains, but there is no way to know if their data is truly legit or inflated.

Its no wonder I liked the AREA P's Slip On performance. It really got the job done.

JJ
 

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Discussion Starter #6
And like Akrapovic claims, there isn't a bit of difference between the Race and EVO systems except the material, Titanium versus Stainless Steel and about 3 pounds, not much really.

I had both systems at the same time and failed to make a photo side by side so you will have to take my word for it.

NOW, the stock headpipes weigh about 6 pounds more than the Akra but thats the only penalty you pay with a Slip On. How big a deal is that to you is what you have to decide.

JJ
 

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Discussion Starter #8
but doesnt the cat being there affect airflow and power?
Yes and so does the size of the pipe. That was the point I was making in previous posts. The cats are there, but the diameter of the cats pipe (section where the cat is located) is larger than the diameter of the Akra pipe in the same area.

So the stock pipe is handicapped by the cats, but has a larger pipe to work with to make up for it as compared to the corresponding Akra.

So since it is larger, it can almost flow as much as the smaller Akra. Make sense?

JJ
 

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not only the short diameter of the cats pipe will decrease the flow,in fact, the bigger diameter and those blocks inside will make turbulence ,and then derease the speed a lot , result in the derease of the flow too.

sorry for my poor english ,but check the principle and construction of the silencer for air rifle by yourself,it would make some sense for you because the stock cats pipe almost have the same function like them

whatever,nice pix,thanks for sharing!
 

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Yes and so does the size of the pipe. That was the point I was making in previous posts. The cats are there, but the diameter of the cats pipe (section where the cat is located) is larger than the diameter of the Akra pipe in the same area.

So the stock pipe is handicapped by the cats, but has a larger pipe to work with to make up for it as compared to the corresponding Akra.

So since it is larger, it can almost flow as much as the smaller Akra. Make sense?

JJ
yeah i get it now, but if u could cut of the cat which shouldnt be that much wouldnt it make it almost like a full sytem?
 

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i'll ad this caveat.........

In AKRA's defense for smaller ID tubing its quite conceivable it increases velocity as with porting etc smaller ID has proven to be benificial.

BD
 

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Discussion Starter #12
i'll ad this caveat.........

In AKRA's defense for smaller ID tubing its quite conceivable it increases velocity as with porting etc smaller ID has proven to be benificial.

BD
I would agree thats true on the intake side dealing with negative pressure (vacum).

But on the exhaust side dealing with positive pressure as one old engine builder once told me, the pistons will push all that exhaust out. It has to.

I think thats why Top Fuel dragsters use 8 short independent fat exhaust pipes.

I once remember reading where Rob Muzzy said that for all out MAX power 4 individual pipes like Honda did on the original 1969 CB750 would make the most power.

I believe that collector stuff is mainly for scavenging and adding the intake flow to begin ASAP.

But looking inside the stock headers, they look basically the same as the Akra.

Simply blowing air thru the pipes, I don't think there would be much difference in flow comparing the 2. I think I am going to rig up some kind of flow bench.

If you got a slip on, your getting a lot of bang for your buck in my opinion with these 08 stock headers. And probably the 04-07 models as well.

The 06-07 has some real nice Titanium header tubes and with a Cat eliminator pipe ala ZX10-Sinner's bike, and his race fit slip on, he has a heck of a combination for the 2nd gen thats prolly as good as a full system.

You notice Akra never builds a pipe design with no other considerations that would make the best power, they instead build a pipe to mimick the stock system of each model.

JJ
 

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Well I have always had the opinion that the difference between a slip-on and full system is very little.I called lee of lee's performance in N.C. and asked about this,he told me that the difference in full system and slip-on both tuned with a power commander would be about 4 H.P.Personally I can't see spending that much more for 4H.P.
 

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sadly over priced by the leaders in moto exhaust systems :(
 

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And like Akrapovic claims, there isn't a bit of difference between the Race and EVO systems except the material, Titanium versus Stainless Steel and about 3 pounds, not much really.

I had both systems at the same time and failed to make a photo side by side so you will have to take my word for it.

NOW, the stock headpipes weigh about 6 pounds more than the Akra but thats the only penalty you pay with a Slip On. How big a deal is that to you is what you have to decide.

JJ
Guess I could hit the gym and settle for a slip-on then!!:lol:
 

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I guess in all getting a full exhaust is just another way to shave weight. Thanks for the pics and the theory Jimmy. Anymore details please keep us informed.
 

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Thanks for the comparison. Good info to have...as I will prolly be able to afford a slip-on...I am a po-boy lol
-S
 

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You cannot compare a good system with stock junk ti system. That is apples to oranges. The things your not looking at are the radius's on the bends, if they are being cheated or not, also the insides of the exhaust where the welds are. Any type of lips rough transition will hurt exhaust pulse, and rod HP.

I would not call the Ti used on the second gen zx-10 good. Mine cracked all over the place.
 

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Discussion Starter #19
You cannot compare a good system with stock junk ti system. That is apples to oranges. The things your not looking at are the radius's on the bends, if they are being cheated or not, also the insides of the exhaust where the welds are. Any type of lips rough transition will hurt exhaust pulse, and rod HP.
Sure I can compare them, that is the purpose of doing this comparison. I never said the stock TI system is as good as the Akra, but it isn't that far off so sayeth my butt dyno.

JJ
 

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Nice comparison Jimmy, you just helped me make up my mind on gettin a full-system. My area-p has done nothing but impress the hell out of me.
 
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