Increase top end without sacrificing low end?


jamie

jamie

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Hi, i hope i dont sound like a freak asking this, as i dont own a civic Ek9 yet.. but as i said i like to do ALL my research even future research before i buy lol :D

anyways i was wondering how do you increase top end wihtout sacrificing the low end acceleration, i mean i have seen that final gear changing thing.. which lowers top end but i mean what mods increase top end without sacrificing the accleration?

Thanks :nice:
 
jamie said:
Hi, i hope i dont sound like a freak asking this, as i dont own a civic Ek9 yet.. but as i said i like to do ALL my research even future research before i buy lol :D

anyways i was wondering how do you increase top end wihtout sacrificing the low end acceleration, i mean i have seen that final gear changing thing.. which lowers top end but i mean what mods increase top end without sacrificing the accleration?

Thanks :nice:
Click to expand...

Tuning...

The exhaust system and intake side are very sensitive to such a high revving 4cyl. Going all out with the exhaust will create no back pressure at all which would rob everything until vtec comes on with 2nd cam.

We were talking about the silencer on cannon type mufflers that makes solid differences when on or off.

If you want more bottom and mid range the get a 4-2-1.

Everyone will have different opinions because one car may feel good to you but someone else might not like it.

Study more on what the pro's say and facts that you can search up.

peak power figure is nothing without torque and mid range which is the main key to promote acceleration. This has been proven on a drag strip and dyno figures.
 
yer i mean since looking on this site i have seen numerous ways of tunning and tbh im getting a bit baffled and confused on it all.. i mean if you got a Fully decated exhaust.. straight through 1 pipe to backbox.. wouldnt that make the top end better and the accelaration at low and mid better?..
 
Im not sure if you already know this, but from what I have gathered...

At full throttle a larger straight pipe will always be better, but at lower rpms and partial throttle, your engine isnt exactly pumping out exhaust gasses like crazy.

This is where you could use the effect of flowing gasses in a smaller pipe to "pull / siphon" out the exhaust gas remaining in the engine after the combustion stroke, hence reducing pumping losses and increasing performance.

To be more technical, every individual pulse of exhaust gas from one cyllinder could be utilized to create a vacuum that 'sucks' the gasses from other cyllinders (coupled with a good valve-overlap design and etc). A large, free-flow pipe destroys the efficiency of such pulses. Midboxes, resonators and similar things serve to reduce the flowrates (and reduce noise), effectively creating the effect of a smaller pipe.

Hence, for everyday driving a straight flow, large diameter exhaust could be less desirable as your engine will feel like it needs more throttle to maintain the same speeds.

However on WOT you want the piping to be bigger for the same effect to be utilized (bigger pulses). Its a compromise you'll have to make while trying to balance out choking (too small), perfect flow, or distorted flow (too large) at different ranges of RPMs and throttle %. Also, at higher rpms, the flow of gasses will be less capable of coping with the engine pumping speeds, the effect is less important and you'd want the piping to be bigger to reduce restrictions instead.

I've experienced both piping designs in their extremes, but all I can say is the effects are really quite small to put too much thought into it. Its not like we're designing a competition engine where tenths of seconds matter... are we? :eek:

Personally I think an exhaust design suited to everyday use is more practical. I'd stick with the stock 2.2" or so for this one, with perhaps a change of muffler (as this seems to be the most restrictive part of the entire EK9 exhaust assembly).

My two cents, do correct me if Im mistaken.
 
i agree...

Wouldn't the intake manifold affect this as well?

I guess the config on my car is just about right. I don't feel much difference in power when the 2nd cam comes on but feel it plenty on the first cam... Silencer on is really great for drivability but downside is... not enough sound.. LOL..

Besides, who would drive their car on the street on 2nd all the time??? It would be better to tune your car to suit your needs...

Having slightly less peak power for low and mid range torque is something i wouldn't go pass on the street. i don't need to drive above 3000rpm anymore because of the torque I get with the silencer. If i'm on track then just remove the silencer.

but really the bottom end and mid range on 1st cam really sucks without silencer.. and gets annoying.

I think this is why Honda developed the K20A to provide everything that we've been trying to do with the B series engine...

mmMmmmMmm... K20A. :p~~~~~~~
 
Hehe yeah a slightly more restrictive exhaust is probably better if its your everyday car. The 'lightness' of a large exhaust would be sweet on the tracks though. Looks like you have a simple solution for both worlds. :eek:

Personally I prefer to hear the awesome engine noise instead of exhausts blazing, so Im pretty happy with the stock muffler. But I might get an itch for something else later...

I havent experienced K20A power, but I'd rather for fear of being disappointed with the B16B afterwards. :p

Quite a number of people prefer the tune-ability of the B series though. Some say that a well sorted B20B can be better than a K20A, with similar levels of tuning, although the K20A is smoother and more linear.
 
Oh. I just realized the point of this thread. :p

Well a change of cams usually doesnt sacrifice low end while increasing top end power. Heard TODA B's are excellent at this?
 
Sorry, I meant to say a change of cams -could probably not- sacrifice low end while improving high end.

I never thought that low to mid-range power would drop that much with the bigger cams though, given that we have 3 sets of cam settings. :shocked:
My question would be was he required to advance/retard the cam phases with the two performance cams? The drop in mid-range is quite bad to be had, given only the cam change with all else being equal.
 
Tri Y design headers gives both low end and high end, i read that they give you the good of both "worlds" 4-1 header and 4 - 2 - 1 header.
 
I think it depends on what you want to do with your car.

Track: then cams would be fine, you don't use 1st cam much.

Street: simple mods ro promote mid range. or supercharger.

I've just listen to a roots type charger on a K20A and Damn!!! that whine is so nice!!! And still keeps the vrrooommmm baaarrrrrrrr!
 
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