Extremely sluggish low-end

[Dwoon]

This is intake we're referring to..... not exhaust.

 

How would torque be lowered by this? If anything, I would expect the response to be better.

 

Can exlpain how the airflow at whatever RPM affects torque, unless you say there is restriction at higher RPM Then less restriction, the better right ?

 

What air velocity you referring to at low RPMs? There's no FI whereby turbo cfm is a factor for lag.

 

Smaller air intake tube is better for low end torque??? You sure about this? Torque is generally associated with the timing advance, and air velocity (at least for NA) is not a factor that it can advance that leh. (at least not that I know of).... (usually temp, AFR).

 

eg. Just for you to think......use 1 straw to drink or 2 is faster? (Then how fast can you swallow if you use 3 straws??? any faster?). So you say maybe use Yakult straw to drink is better? Ok, not so good example earlier. Say use those huge diameter bubble tea straw, normal straw and yakult straw to drink..... what difference do you get?

 

Perhaps you can enlighten???

 

 

Oh, it does make a very noticeable difference.

 

Sometimes, its not bigger and free flow is better esp. at how RPM.

 

What matters most at low RPM is air velocity. In fact, smaller tubes are better for low end torque because this increase the air speed going into your engine.

Edited April 16, 2010 by Dwoon

[Jamesc]

When you put on nice 17" rims

 

why you wanna accelerate away so fast!

 

Accelerate away slowly to let people around

 

admire your nice rims a little longer! :)

[Celicagt42010]

I trust the CAI installer.. he's out in the market for very long... i have no low-end drop with stock rim before.. but only with 17"..

 

I don't know what was done to the intake. But if you retain the stock air box and just add a duct to the air box to take in cooler air from outside the engine bay, it won't affect your power. However, the the entire stock air assembly was removed, then it will cause your low end torque to drop.

 

[The_young_once]

I think avante on 17" looks just about right, definitely your pick up is suffering, but the handling, roll, stability at high speeds are well justify losing out say (eg, 12.5km/l become 11.3 km/l), 17's fit the avante wheel well and overall proportions nicely, look at so many Forte SX trim on 17's nowadays, just nice too bad, live with the sluggish a bit brother, at most step more, fc a bit suffer, but that's ok

[Celicagt42010]

This is intake we're referring to..... not exhaust.

 

How would torque be lowered by this? If anything, I would expect the response to be better.

 

Can exlpain how the airflow at whatever RPM affects torque, unless you say there is restriction at higher RPM Then less restriction, the better right ?

 

What air velocity you referring to at low RPMs? There's no FI whereby turbo cfm is a factor for lag.

 

Smaller air intake tube is better for low end torque??? You sure about this? Torque is generally associated with the timing advance, and air velocity (at least for NA) is not a factor that it can advance that leh. (at least not that I know of).... (usually temp, AFR).

 

eg. Just for you to think......use 1 straw to drink or 2 is faster? (Then how fact can you swallow if you use 3 straws??? any faster?). So you say maybe use Yakult straw to drink is better? Ok, not so good example earlier. Say use those huge diameter bubble tea straw, normal straw and yakult straw to drink..... what difference do you get?

 

Perhaps you can enlighten???

 

Yes, we are referring to NA here not Turbo.

 

http://www.cdxetextbook.com/engines/motive...taryengine.html

 

http://www.motorcycleproject.com/motorcycl...ws-porting.html

 

Check out on how the porting may actually make car slower and port valves used in the renesis engine.

 

Btw, valve lift and duration also affects air velocity. Thats why low end torque requires short duration and low lift to increase air velocity and swirling of the air to improve fuel mixing.

 

 

 

[Dwoon]

That's engine design.....

 

But for a fixed engine design (whatever it is) can explain how would a smaller & more restrictive intake pipe improve the torque. This is somthing really new to me.

 

Thanks

 

[Celicagt42010]

That's engine design.....

 

But for a fixed engine design (whatever it is) can explain how would a smaller & more restrictive intake pipe improve the torque. This is somthing really new to me.

 

Thanks

 

Hi! I am not sure if you have read my posts correctly but I did stress on low end torque. What applies to low end does no apply to high end.

 

Putting a larger pipe is to allow more air to enter the engine when it needs more air. Correct? This only happens at high RPM cause a smaller pipe is a restriction. But when the engine is at low RPM, the smaller pipe no longer becomes a restriction.

 

As I have mentioned before, a larger pipe causes the air to flow slower thru the pipe. Air velocity is very critical to volumetric efficiency and torque (which is also related to power). Thats why its not bigger = better. It has to be balanced with the air flow required by the engine.

 

The renesis article shows why designers uses valves to block of air paths into the engine at low RPM. Its to have a smaller and more restrictive path and hence increase air velocity.

 

The motorcycle article talks about why porting up the head may not be a good idea and it may actually reduce power at low end because it reduces air velocity.

[Jamesc]

Extremely sluggish low-end

 

My wife has the same problem too! :)

[Fuelsaver]

I've been experiencing sluggish low-end especially during 2nd gear after i change my stock 15" to 17" recently. i've changed k&n drop-in filter & customize cai. the problem could be due to the 17".. and yes, i'm on lenso samurai sc01 (it's considered as the "lightweight" cat w/ 7kg per rim.)

 

was wondering what can be the next steps to improve my low-end? i've no issue with mid/high-end and can feel the power with anything above 5k rpm.

 

i'm looking for parts that don't void warranty.. please advise if any of the below that helps and feel free to suggest if i do missed out any.

 

- change stock sparks plug

- change stock sparks plug cable

- pro steel RS brake hose kit to improve stock brake kit

- lta-approved exo (sadly, in the market current don't have any)

- uniQ piggyback

 

yes, i'm driving avante 1.6MT.

 

thanks.

 

power is never enuf. u will upgrade after upgrade.

 

cable, hose, exo, uniQ all will have part / all warranty voided, depending wat prob it had caused to other parts of car.

 

hope it's not wet blanket to u -

1. chg to stock rims, or trade for 16"

2. revert to stock air intake setup, or chk for any sharp bend in ur cai routing. actually ur orig car oredi cai'ed; u no need to do anythin to air intake unless u going for open pod w/cai.

 

cheers.

[Dwoon]

Still don't understand..... those are engine design considerations... not what is supplying it.

 

From the renesis engine article:

 

At low engine speeds, air flows into the engine through the primary intake ducts only, keeping the air velocity in the manifold high, which provides better air fuel mixing.

 

From the motorcycle article :

 

First, just because a head is made to flow more air doesn't mean the engine will achieve that quantity of air movement. After all, the head doesn't move the air through itself, the rest of the engine does. If the engine can't support the head's potential, it is just that -- potential, and not practical reality.

 

Doesn't say it reduces torque. As said, its engine's design consideration for flow and its limitations.

 

As I understand, flow velocity is not equal to to volume (cfm) of air which is what is important... no? That being said, it is the volume of air available to the engine (not the internal engine's construction). When the engine draws the air..... is volume more important or is the air velocity (but cannot supply sufficient in time).

 

With my earlier examples using straws.... would one draw more air in using a large bubble tea straw or a yakult staw, in a faster time to supply the same volume irrespective of engine design (flow rate inside straws is different)

 

Would capability to supply more air faster to engine, result in reduced torque? (Maybe not improve torque if the engine cannot make full use of the added capacity, but reducing it?) Going back to the topic, TS complained a loss in torque.... would a more free flow intake cause this?

Edited April 16, 2010 by Dwoon

[Showtime]

Hi! I am not sure if you have read my posts correctly but I did stress on low end torque. What applies to low end does no apply to high end.

 

Putting a larger pipe is to allow more air to enter the engine when it needs more air. Correct? This only happens at high RPM cause a smaller pipe is a restriction. But when the engine is at low RPM, the smaller pipe no longer becomes a restriction.

 

As I have mentioned before, a larger pipe causes the air to flow slower thru the pipe. Air velocity is very critical to volumetric efficiency and torque (which is also related to power). Thats why its not bigger = better. It has to be balanced with the air flow required by the engine.

 

The renesis article shows why designers uses valves to block of air paths into the engine at low RPM. Its to have a smaller and more restrictive path and hence increase air velocity.

 

The motorcycle article talks about why porting up the head may not be a good idea and it may actually reduce power at low end because it reduces air velocity.

 

yes it does. and thats due to the larger x-sectional area. but doesn't the volumetric flow rate and hence, mass flow rate remain the same?

[So_nice]

u might wanna change to a bigger 4-2-1..as for rims, i still think 17" are more suitable for 1.8 and above.

[Ken4555]

Actually there are customized extractor out in the market already. Not locally but overseas. I can feel slight improvement on throttle especially on stock rim.. but the improvement eventually go away after upgrading to 17".

 

Kinda regretted changing to 17" tho.. should have just upgrade to 16" will do.

 

my car original 15 i upgrade to 16... from 185 i upgrade to 205... cheap taiwan made RM rims quite heavy... LOGICALLY shd be slower... but my other light mods make up for it so i dont feel less power but rather better grip and stability... and i'm sure your car is gripper and better right? would you want back your little bit of power and better FC for smaller rims and skinnier tyres? not me...

 

my bro's car 16" he change to 225/40/18... end up size of whole wheel bigger than stock also... except for being much noiser... no noticeable change in power... he is using original wed sport with tyres costed him like around 3k...

 

bro no offense but pay peanuts get monkeys...

can't hv best of both worlds like eg. coilovers fantastic grip and stability but bumpy uncomfortable ride...

 

unless you get a high performance car if not hv to live with less low end...

 

bro did you use to ride? you know a Cagiva Mito 125? Benelli125? Yamaha LC125? all low end hopeless... but when high revs compresson very high... shiok...

 

moto-cross bikes... eg. KDX200.. WR200... funny bike SDR200... all the power comes the moment you release the clutch but top end so flat...

 

sorry think i out of point liao....

[Ken4555]

I know it's not a performance car.. If i would want a performance car in the first place.. i would had go for more high-end performance car.. but it's a passion to slowly upgrade to market's performance parts. it's a joy to drive a not-so-stock saloon car..

 

personal opinion tho..

 

agreed..

 

but mods shd be sensible and done with taste..........

 

......... but everyone's knowledge and taste different...

 

so i'm not making any sense.... haha

[Ken4555]

it is like tat when 15 to 17.

 

when i change it last time to light wt rims,

my fuel consumption down by 50km.

and slower pk up.

if heavier rims lucky worst.

 

but hell alot more grip, corner no brakes like no tomorrow.

16" cannot match the grip offering.

 

if u want a bigger rim, get 16 jus nice for the grip and pick up.

For looks 17 lor and get use to it lor.

 

i need to ask you this bro... cause you said 16'" cannot meet the 17" grip...

 

you see ah... Forte ss model original tyres 205(confirmed)/45(i think)/17(confirmed).....

 

i use 215/50/16..... for my 16" rims... this size is very rare... only some tyre brands carry this size...

 

So who got better grip? if considering both brand and model of tyre same?

[Ken4555]

I fully agree. Y CAI/Open Pod?

 

Since you say that your rims are lightweight, then the prob of sluggish low end could be due to your Open Pod.

 

Stock is best brother...

 

Dun spend so much money since your car is NA.

 

i'm a strong fan of open pods the bigger the better i just love the sound.....

 

but the fact is stock air box is best.... unless our engine mods very extensive like turbo or P/P etc...

[Ken4555]

Hmmm.... why would CAI/Pod affect the pickup? This is the input to engine.... doesn't affect the back pressure at all (that's exhaust) . If you ask me, it'll give faster throttle rev response due to more free flow of air into the engine.

 

Question for TS. Did you change the tube diameter whereby your MAF/MAP sensor is mounted? (That requires tuning otherwise it'll screw up all your AFR). I hope you didn't mess around with that when doing your CAI piping. This should be done for piping upfront of the air flow sensor and nothing at or after, leading to the engine. (Unless you intend to tune)

 

If the above holds true..... then tis your added weight of the wheels/tyres. To get some low end back, you might want to try a lightened crank pulley. (will most likely void warranty) Leave the alternator pulley alone (some will recommend you do that too), else your battery charging might be adversely affected. (unless you know what you're doing)

 

bro... most family saloons modded with just a open pod (watever size filter in the market steel or paper) immediately lowers your low-end power... you can ask around....

[Versatile]

my car original 15 i upgrade to 16... from 185 i upgrade to 205... cheap taiwan made RM rims quite heavy... LOGICALLY shd be slower... but my other light mods make up for it so i dont feel less power but rather better grip and stability... and i'm sure your car is gripper and better right? would you want back your little bit of power and better FC for smaller rims and skinnier tyres? not me...

 

my bro's car 16" he change to 225/40/18... end up size of whole wheel bigger than stock also... except for being much noiser... no noticeable change in power... he is using original wed sport with tyres costed him like around 3k...

 

bro no offense but pay peanuts get monkeys...

can't hv best of both worlds like eg. coilovers fantastic grip and stability but bumpy uncomfortable ride...

 

unless you get a high performance car if not hv to live with less low end...

 

bro did you use to ride? you know a Cagiva Mito 125? Benelli125? Yamaha LC125? all low end hopeless... but when high revs compresson very high... shiok...

 

moto-cross bikes... eg. KDX200.. WR200... funny bike SDR200... all the power comes the moment you release the clutch but top end so flat...

 

sorry think i out of point liao....

 

No worries bro. Like i said, it's the joy & passion and with the given 121bhp given.. i just want to try to tune it to the max. I've been driving NA car for the past 5 years.. if i want power, i would have go for rex or any tc cars. I guess should be a give and take issue.. with the low-end power gone.. i'm also glad that i've choosen the right rim/tire for better stability and grip.

 

i'm fine with low-end actually, just trying to find out is there any way to maximize the performance. i would like to thanks all mcf-ers for all the vaild pointers and comments. i learned alot from all the comments here..

 

:)

 

Cheers!

Edited April 16, 2010 by Versatile