How to improve low end torque for auto car...

[Elfenstar]

I've not seen much data about exhaust flow. But I'd think a straight flow muffler will allow exhaust gas to escape faster in all RPM. Stock muffler design is usually quite conservative and restrictive.

 

I believe switching to larger exhaust pipes is the one that can negatively affects low rpm performance.

 

It reduces torque because with less backpressure means more gases escapes and due to the overlap of the intake and exhaust valves, some/more of the intake charge gets out. thus less fuel and air = less strong explosion = less torque and power. This is minimised or totally negated at higher rpms and you get higher power at the top because the engine can breath easier.

 

Some ecu's can compensate to a certain extent in closed loop cycle but might still be fooled because of the oxygen content from the fresh charge (i.e. thinks the ratio is alright or think that it might be running lean).

 

Thats why a perfect match of exhaust to intake means you can get better power and torque all around. the more aggresive exhaust cam helps cheat a lil on this by having the duration shorter/later but increasing lift to allow roughly the amt of gases to escape

 

Edit: i forgot to mention apparantly BMW's ECUs have managed to get around this (or so their geeks say) so if you drive an auto BMW, feel free to upgrade and let me know [laugh]

Edited September 19, 2006 by Elfenstar

[Elfenstar]

ots of ppl frm wrkshop whom i spoke to most of the time will recommended semi flow for auto... due to autocars need certain back pressure for the low end

 

Rubbish. the loses are due to what i said before. and the reason its felt more in autos is because a certain percentage of torque is lost due to the converter so the loss is more noticeable.

[Sash7]

so bro, meaning straight thru is ok for auto? but if the loss is really feel by auto cars due to the converter using straight thru... so not really suitable for auto rite?

[Limws1]

... as above.. anyone got any advice?

cheers

 

What car are you driving?

 

You can try replacing the stock underdrive pulley to light weight pulley. This is stage 1. Stage 2 will also include light weight water pump and aircon pullies.

 

Do a search on the Net for 'underdrive pulley' and 'dyno'.

[Wolverine]

no plobem one leh lah ...stet too oso can

[Elfenstar]

The trick is to get your setup right so that theres no loss. in the engine, one change will have a chain reaction so you need to get the chain reation right or get the ecu tuned so that everything is hunky-dory again.

[Sash7]

yo bro... so straight thru for auto can pervent low end losses.... so we have to do frm intake all the way to the exhuast... wat kind of set up is idea for ... let say a 1500cc auto car(my car)my exhuast is operated to semi-flow... to me not so much of a different for low end...but on high end can feel the car breathe better as for my intake is juz normal drop in KNN... thinking of getting enclosed pod with CAI...as for header 4-2-1? will it do any good???? as for retune of ecu... meaning we get a piggy back to fully tune it?

[Elfenstar]

If your exhaust is properly matched to your intake then yes, you will have power and torque gains throughout the rev range.

 

Setup wise is gonna be an issue as it involves matching the components. This also involves the header (I prefer 4-1 in tuned length).

 

As for retuning, i would suggest going with whatever your tuner is best at.

[Sash7]

hmmmmm.... ok thks... actually i dun really have a turner here... think most of us is more trial n error kind of things ... think next thing i will do is to change the enclosed pod n c whether there is a improvement or not...

[Elfenstar]

what car are u driving again???

[Sash7]

me driving a honda civic EU1 model 1.5 vti.... u in aus rite?... should knw how it look like....think is common thr.... got 3door somemore...

[Elfenstar]

I think i know which one. Havent seen that many on the road though and the last civic which was less than 1.8l (bar the hybrid) was the ek series.

 

you shouldnt have too many problems finding good quality parts. It is a civic. AEM makes very good parts for them minus the crazy prices that jap parts have .

 

Have a look at the us honda forums. they're more crazy abt civics than the japs .

 

if you want, the best way is to start properly. a good port and polish of the head with a thinner headgasket to increase compression with a tune. Its more work and more exp than the rest i mentioned but it gives you a good start as you don't have to worry too much abt how the head flows. If you can get a good exhaust and intake system with adjustable cam pulleys with the port and polish (saves you retuning costs and saves you labour on fitting the pulleys). You can go cams to save a lil more at this stage to save even more on future labour.

Edited September 19, 2006 by Elfenstar

[Sozo]

Ah......... I've just installed a simple device and it really improved the low end torque, it just added on no mod needed. by the way i drive a Honda Edix 1.7, PM me if you want to know more. One more thing, it has 14 days money back policy.

[Lorrliew]

Cannot share info openly meh?

[Sozo]

Not so nice lah... wait kanna complain say i'm trying market something. to be frank i don't mind sharing (Good Thing must share mah)

Edited September 19, 2006 by Sozo

[Mikeyeo]

If our car is still under warranty, it is difficult to change to better performance parts such as increasing th manifold, air-intake, etc. By so doing would void the warranty.

 

The only things can owners of new cars can do is to add and/or replace certain stock components to better performance ones. This is what I have done on my 6 months old car without affecting the warranty.

 

I installed a cyclone air-intake, a pair of box-shaped magnetic fuel crackers along the fuel line, a voltage stabilizer and 9 points grounding cables, a Superione to further improve the efficiency of the combustion process of the the air. I replaced the stock spark plugs, plug cables and filter to high performance ones and the stock super heavy main crank pulley to super lightweight.

 

By just doing the above, my Mitsubishi Lancer is pretty fast at pick-up by steppng lightly on the throttle, acceleration improved significantly and overtaking is a breeze In addition, I am getting higher torque with lower rpm. Last by not least, save on fuel consumption. I retained the original size of my wheel which is 195x60x15 except that I changed the tires to performance tires.

 

My neighbour who drive a 3 months old 1.6 Nissan Sunny has complaint to me about lack of power and sluggishness of the engine. After showing him what I have done to my car and sat while I drove, he found it so 'shiok' that he is also going to do the same to his car.

[Phochem]

U sure by changing to light weight pulley will not void your warranty?

[Paikia_rav]

Most automatic cars suffers at low end as compared to manual ones. But come to think about it, the engines are basically the same, then why the differences? Then when u thought about it, you realised that the difference in the 2 is the gearbox. Not all straightforward mods suitable for a manual is suitable for a automatic gearbox car.

 

There had been some discussions about exhaust systems for automatic gearboxs, & most will advise not to have a complete straight through as the torque convertor in the autogearbox will casue a slag in transfer of power through the gears, hence it actually suffers from at low end instead, of course unless the car's displacement is big enough or it comes with forced induction whereby there is less reliance on back pressure.

 

Automatic gearbox (torque convertors) normally have further gear ratios to cater for the lesser gears (usually 4) and hence the power distribution are wider.

 

Try a light weight crank pulley. Although it does not increases horsepower, it actually creates less loss of power through the delivery. The difference of lighter throttle feel will be best felt when changing from gear 1 to gear 2.

 

Cold Air Intake might also do some good. This does not necessarily mean an oped pod as it actually might cause more harm than good if not configured properly to draw cool air into the intake manifold. (Cool air is denser and hence contains more oxygen for combustion) Stock ait filter box will suffice should a simple configuration of flexi funnel to draw cool air from external into the intake nozzle. A drop in aftermarket filter might be good as stock paper filters are more restrictive.

 

ECU re-mappings are good when u do some major mods like exhaust change, TC/SC, performance cams/piston and simple mods like CAI, muffler only, crank pulleys, etc need not as the stock can cope with these.

 

One thing I learn over the years of driving is, if you want more power, the cheapest and most reliable mod is to cut down on weight. Remove spare tyre, lightweight rims, dump your amplifiers and subwoofers which may weigh up to 50kg, use minimum required rim/tyre size to reduce power loss, go for diet, ask gf take taxis instead etc. The issue that matters is power to weight/drag ratio. Even if you drive a 200bhp car weighing at 1800kg with everything in, it might still lose in pickup as compared to a 120bhp in a 1000kg car.