Tailpipe fuel consumption effect

[uls]

hindi ba mas malakas sa gas yung ganun?

you lose low end torque, but gain hp at the top end

[uls]

in regulated places, you can replace anything before and after the cat

basta you have a cat

may nabibiling high flow cat if you want less restriction

anyway, if you're in the Phils., you don't need a cat

you can replace the entire exhaust system from manifold to tail pipe

[kurby]

you lose low end torque, but gain hp at the top end

in layman's term po? mababa ang hatak sa low rpm? pero lalakas ang power at high rpm? so you need to step on the gas pedal more for torque? tama po ba?

in regulated places, you can replace anything before and after the cat

basta you have a cat

may nabibiling high flow cat if you want less restriction

anyway, if you're in the Phils., you don't need a cat

you can replace the entire exhaust system from manifold to tail pipe

ang 97' series 3 ay may cat converter pero, walang o2 sensor? wierd..

[uls]

in layman's term po? mababa ang hatak sa low rpm? pero lalakas ang power at high rpm? so you need to step on the gas pedal more for torque? tama po ba?

tama po

ang 97' series 3 ay may cat converter pero, walang o2 sensor? wierd..

meron yan

impossible wala

[kurby]

tama po



meron yan

impossible wala

wala po eh... hinahanap ko. walng front or rear. ewan ko nga ba bakit wala.

[uls]

akala ko 97 3 series (BMW)

yun pala 97 series 3 (Sentra)

ewan ko lang, baka wala talaga O2 sensor

di ako familiar sa Nissan

pero pag EFI dapat may O2 sensor

baka tinanggal

if the O2 sensor is disconnected, the ECU will think you're running lean, so it will richen up the A/F mixture (inject more gas)

[erick_214]

Elow Dusky...

Tanong ko lang sana,,, I have a Hi-ace 3.0 Turbo A/T...

Ngayon the Q is,,,kung sakaling magpalit ako ng tailpipe(freeflow/bigger) eh mas bibilis ba yung pag-ikot ng turbo at mas marami siyang ma-iinduce na air sa cylinders? Will it make the air-fuel micture leaner? Will it give my van a little bit more HP?

TIA...

Erick

[duskylim]

Dear eric:

Please go to page1 and 2 and read my posts there - that should answer your questions regarding the relationship of a turbo with the exhaust system.

I believe my post #17 will be the most informative.

Regarding lean-out well that's a phenomenon most associated with gasoline/spark ignition engines, diesels engines ALWAYS run LEAN.

There is ALWAYS excess air in a diesel - ranging from greater than 125 parts air to 1 part fuel (by weight) at idle to maybe 22 to 20 parts air to 1 part fuel at full throttle.

In contrast, gasoline engines run about 16 parts air to fuel on lean cruise about 12.5 parts air to fuel on hard acceleration and have a 14.7 parts air to fuel stoichiometric ratio.

Power in a diesel engine is controlled by the amount of fuel injected, there is no real control over air.

Diesels do not run on stoichiometric mixtures that is, the exact amount of fuel needed to burn the oxygen in the air charge completely - they always have excess air.

If the quantity of fuel injected is made to approach the Stoichiometric ratio, more and more black soot, smoke and particulates are formed - so the maximum quantity of fuel that can be injected (maximum delivery) is determined by this - what is called the 'smoke limit'.

Hope this helps.

Best Regards,

Dusky Lim

P.S. feel free to ask if you have any more questions

[Wh1stl3r]

*dusky
Would an AFR of 15 (locally available diesel) give you black smoke? What's the richest you can go on locally available diesel without doing an EDSA bus impression?

[duskylim]

Dear whistler:

Trying to produce a stoichiometric ratio on a high-speed diesel engine will result in smoke emissions so black it will blot out the sun.

An air-fuel ratio of 15 : 1 is applicable to gasoline engines but not to diesels.

Diesel fuel has a stoichiometric ratio of around to 14.5 : 1, similar to that of a gasoline engines which is 14.7 : 1.

Although that is the 'chemically correct' ratio needed to burn all the air and fuel completely, there are FUNDAMENTAL limitations in the diesel combustion process that prevent this from being achieved.

The MAIN problem is that diesel fuel is introduced into the combustion chamber as a LIQUID.

In contrast a gasoline engine introduces the fuel as a VAPOR or gas.

Liquids do NOT burn, only vapors do.

Even if the fuel is solid like coal, paper or wood, it actually undergoes a period of gasification BEFORE it can burn.

In a gasoline engine, by the time combustion begins, the fuel has been vaporized and thoroughly mixed with air - just the right conditions for ignition by a spark plug.

In a diesel, the fuel is introduced as a fine liquid spray and there is a period of time in which it must mix with the combustion air and vaporize BEFORE it can start to burn.

This is called ignition delay or the delay period.

Basically a diesel engine must vaporize and mix it's fuel and air almost at the very same time that it needs to burn it.

The fuel that did not mix properly with air before burning becomes SOOT.

Adding more fuel does NOT improve the mixing process - it just makes more SOOT.

In a high-speed diesel engine there is just not enough time for all the air and fuel to mix together properly to burn completely.

Conditions are different for low-speed diesel engines - because things happen comparatively slowly.

The air-fuel ratios used by automotive diesel engines on hard acceleration are the richest realistically achievable - that's why you blow smoke when you step on it.

Let me say again the maximum air-fuel ratio is determined by the 'smoke limit' - adding more fuel only makes more smoke.

Although the engine is allowed to approach the smoke limit during hard acceleration under load, it is not intended to run at the smoke limit continuously.

If the engine was allowed to run at that air-fuel ratio all the time it would suffer serious damage very quickly.

The large amounts of carbon soot formed would foul the piston rings - jamming them and abrading the cylinder walls.

It would also contaminate the oil and quickly cause a breakdown in it's lubricating properties.

Carbon would build up around the valve seats and cause them to burn and leak.

The strong reducing atmosphere (from the excess unburned fuel) in the vicinity of the injection equipment will cause pitting and corrosion.

As you can see there are many issues to address if you want more power from your diesel engine.

Feel free to ask if you want to know more.

Best Regards,

Dusky Lim