What are you driving now?

[Nicholasng925]

Hmm, wouldn't the car feel weird if drive without boost? In NA engine, the air enters from air filter and went straight on into the throttle body but for turbo, the air still need to go into the compressor and travel through the intercooler before reaching the throttle body. Such a long path for the air to take and since there is no boost at all, I guess the compressor is not sucking in air strongly like when there is boost?

Run without boost probably can help you to save more fuel.

Are you adjusting boost on the go inside your car with boost controller?

Nope not at all. The car works just as usual without boost, you can treat the boost as an additional amount of air pushing into the throttle body. Now you can imagine, with boost the suction of air into the air filter is way stronger than without.

Running without boost definitely saves more fuel than with boost. But for lighter cars such as bolt-on Myvis, running with boost might save more fuel. It really depends. Sometimes it's not about the boost level but the rpm. The best rpm for fuel efficiency should be around 2.4k, but less than 3k.

I have a Works Engineering manual boost controller under the car bonnet.

 

[RENESIS VIII]

Yeah, 1996 1.6L.. 20 years now. Not giving much problem. As I can remember, parts that I have replaced are alternator (kong already, did not charge, ok la after 20 years), radiator hoses, plug cable, and add some battery negative cables (plus all parts for maintenance of course). Other than that, its all stock. I like it that way. Maybe wana swap engine later but after get another family car..

These old mitsubishi engines are quite reliable. But I heard people saying 4G9 engines are not as reliable as 4G1 engine. But looks like yours is quite good. Manual?

 

[RENESIS VIII]

Nope not at all. The car works just as usual without boost, you can treat the boost as an additional amount of air pushing into the throttle body. Now you can imagine, with boost the suction of air into the air filter is way stronger than without.

Running without boost definitely saves more fuel than with boost. But for lighter cars such as bolt-on Myvis, running with boost might save more fuel. It really depends. Sometimes it's not about the boost level but the rpm. The best rpm for fuel efficiency should be around 2.4k, but less than 3k.

I have a Works Engineering manual boost controller under the car bonnet.

I see. So even at 0 boost, I think the compressor is still sucking in air like usual, just not at high intensity/pressure like it is during boost.

So when adjusting boost, you need to adjust it by opening your bonnet or you can do it from interior?

 

[jebatdex]

These old mitsubishi engines are quite reliable. But I heard people saying 4G9 engines are not as reliable as 4G1 engine. But looks like yours is quite good. Manual?

yeah manual, and yes I forgot, i change the gearbox already once, 2 years back, bearing problem. Long story for my gearbox problem, happened its just bearing problem, meaning if change bearing should be fine (some sound coming out), unfortunately that time I did not find the correct gearbox specialist and I went to the wrong workshop and he con me. I go through all Tribunal Pengguna thing and got back my money (fuh!).

For me, its quite reliable. IMHO, any old Mitsu engines, if maintained should be OK. Depends on many factors such as maintenance, driving style, usage etc..

 

[Nicholasng925]

I see. So even at 0 boost, I think the compressor is still sucking in air like usual, just not at high intensity/pressure like it is during boost.

So when adjusting boost, you need to adjust it by opening your bonnet or you can do it from interior?

One more thing to add, I think even though the path taken by the air for turbocharged cars is slightly longer than NA cars, they are quite efficient so one will barely feel the path difference. Of course the piping length and design will make a difference between two turbocharged cars, ceteris paribus.

Most of the time people don't really adjust boost levels, just decide on one intended boost setting and forget about it. You can always drive below that boost level should you just want to relax and cruise. Your throttle pedal is the key.

 

[RENESIS VIII]

yeah manual, and yes I forgot, i change the gearbox already once, 2 years back, bearing problem. Long story for my gearbox problem, happened its just bearing problem, meaning if change bearing should be fine (some sound coming out), unfortunately that time I did not find the correct gearbox specialist and I went to the wrong workshop and he con me. I go through all Tribunal Pengguna thing and got back my money (fuh!).

For me, its quite reliable. IMHO, any old Mitsu engines, if maintained should be OK. Depends on many factors such as maintenance, driving style, usage etc..

Woah, tribunal case. Then you probably have heard before of DanzEterna and all his tribunal case? Since you are an old ZTH member and Danz posted quite a lot of stories regarding tribunal. So at the end you got back your money and bought another gearbox?

I agree. old Mitsubishi engines are quite tough and can withstand a lot of things even when not very well maintained. Well, since they are quite a big player in heavy industry machinery field, I'm sure their experience and expertise helped them a lot when they are manufacturing car engines. Besides, old Proton during 80s and 90s still uses a lot of parts directly from Mitsubishi themselves and I believe quality control is also better back then. After 90s era, I guess that is where Proton start to go downhill in terms of quality control.

One more thing to add, I think even though the path taken by the air for turbocharged cars is slightly longer than NA cars, they are quite efficient so one will barely feel the path difference. Of course the piping length and design will make a difference between two turbocharged cars, ceteris paribus.

Most of the time people don't really adjust boost levels, just decide on one intended boost setting and forget about it. You can always drive below that boost level should you just want to relax and cruise. Your throttle pedal is the key.

Well, since the path for the intake air to travel is longer, I thought perhaps on lower or 0 boost, the car might feel laggy because the pressure is not there to force the air to move quickly.

Oh, I actually thought you can set it to like 0 boost if you want.

 

[Nicholasng925]

Well, since the path for the intake air to travel is longer, I thought perhaps on lower or 0 boost, the car might feel laggy because the pressure is not there to force the air to move quickly.

Oh, I actually thought you can set it to like 0 boost if you want.

You are right in a way, for negative boost levels. The laggy feeling is the same as the reduction of low end torque, meaning it is not as responsive at low rpm as compared to City and Vios or even Myvi. I tend to compare my car on vacuum area with City because my parents have two City's at home, so I am used to that kind of responsive low end torque. At 0-bar, my car feels good just like NA car to me.

Set it to 0-bar boost? Hahaha then what's the point of having a turbo setup? The minimum boost level I can set is aligned with my wastegate spring rate, which is 0.5 bar. Anything lower means my car is having a boost leak somewhere.

 

[RENESIS VIII]

You are right in a way, for negative boost levels. The laggy feeling is the same as the reduction of low end torque, meaning it is not as responsive at low rpm as compared to City and Vios or even Myvi. I tend to compare my car on vacuum area with City because my parents have two City's at home, so I am used to that kind of responsive low end torque. At 0-bar, my car feels good just like NA car to me.

Set it to 0-bar boost? Hahaha then what's the point of having a turbo setup? The minimum boost level I can set is aligned with my wastegate spring rate, which is 0.5 bar. Anything lower means my car is having a boost leak somewhere.

If the City you have at home is the one using CVT gearbox, then I think the low end torque response is very good as the gear ratio can be adjusted to suit lower RPM usage.

Wait, I think maybe I misunderstood you earlier when you mention 0 bar boost. You mean your engine will be running at 0-bar when it is under 2000rpm is it?

 

[Nicholasng925]

If the City you have at home is the one using CVT gearbox, then I think the low end torque response is very good as the gear ratio can be adjusted to suit lower RPM usage.

Wait, I think maybe I misunderstood you earlier when you mention 0 bar boost. You mean your engine will be running at 0-bar when it is under 2000rpm is it?

I think I should explain a bit more on the experience of driving a turbocharged car haha!

At idling (0% throttle), the boost level is -60 kPA.
At light throttle about 10-20%, the boost level will increase to maybe -40kPA to -20kPA.
At half throttle (50%), it will go up to 0-bar.

All these are vacuum area. Normally when we are driving with light load, we seldom drive past 0-bar because 0-bar is similar to a NA car (for me).

Beyond half throttle, the boost will start kicking in to positive region, and there's where all the fun are.

Cruising at normal speed (90-100km/h) doesn't require boost to sustain the speed so the reading may be around -40kPA. Cruising at higher speed to maybe 120km/h will demand higher pedal pressure at -20kPA. If I maintain my pedal at 0-bar, the maximum cruising speed will be around 130-140 km/h.

Any speed beyond, I will require some boost to help me sustain. I remember I was boosting 0.3-0.5 bar just to maintain my speed at 160km/h.

Back to your question, there is something called turbo spool or turbo lag. How quickly a turbo spool depends on many factors such as the size of turbine, the size of intercooler, piping length and design etc.

When my engine is running at below 2000rpm, the turbo is not spinning quick enough so the most it can go up to is 0-bar, but not able to generate sufficient boost until positive boost region.

I think someone else can help to explain a bit more hahaha! :sleep:

 

[lsm1991]

These old mitsubishi engines are quite reliable. But I heard people saying 4G9 engines are not as reliable as 4G1 engine. But looks like yours is quite good. Manual?

all also macam tanks.... 4g1x's were even simpler hence technically more reliable (most had minimal sensors)

old mitsu's... they tappet away, they tend leak but damn they last forever

 

[RENESIS VIII]

I think I should explain a bit more on the experience of driving a turbocharged car haha!

At idling (0% throttle), the boost level is -60 kPA.
At light throttle about 10-20%, the boost level will increase to maybe -40kPA to -20kPA.
At half throttle (50%), it will go up to 0-bar.

All these are vacuum area. Normally when we are driving with light load, we seldom drive past 0-bar because 0-bar is similar to a NA car (for me).

Beyond half throttle, the boost will start kicking in to positive region, and there's where all the fun are.

Cruising at normal speed (90-100km/h) doesn't require boost to sustain the speed so the reading may be around -40kPA. Cruising at higher speed to maybe 120km/h will demand higher pedal pressure at -20kPA. If I maintain my pedal at 0-bar, the maximum cruising speed will be around 130-140 km/h.

Any speed beyond, I will require some boost to help me sustain. I remember I was boosting 0.3-0.5 bar just to maintain my speed at 160km/h.

Back to your question, there is something called turbo spool or turbo lag. How quickly a turbo spool depends on many factors such as the size of turbine, the size of intercooler, piping length and design etc.

When my engine is running at below 2000rpm, the turbo is not spinning quick enough so the most it can go up to is 0-bar, but not able to generate sufficient boost until positive boost region.

I think someone else can help to explain a bit more hahaha! :sleep:

Thank you very much for your long explanation. Now this helps me to understand more on turbocharged engine operation during lower RPM. Never actually gave much thought on this topic about low boost level.

all also macam tanks.... 4g1x's were even simpler hence technically more reliable (most had minimal sensors)

old mitsu's... they tappet away, they tend leak but damn they last forever

I guess simple is gold for old 4G1 engine, hahaha. But how does the newer DOHC 4G15 fares, I don't know. That one is like a completely different engine already.

Tappet sound is a common characteristics for most old Mitsubishi engines. Leak can be solved with oil seal change.

 

[sweelt]

Turbo help u to reach the required kmh faster. More air force in, more powahhh... Colder the air, the better engine performed.

 

[RENESIS VIII]

Turbo help u to reach the required kmh faster. More air force in, more powahhh... Colder the air, the better engine performed.

More air + fuel = more power

 

[vr2turbo]

0 bar means no boost at all? If no boost, still can run properly?

No problem. So, the boost lag under 2k rpm means nothing much to you since you rarely keep it below 2k rpm.

O is same as NA loh! NA where got boost......lol

 

[RENESIS VIII]

O is same as NA loh! NA where got boost......lol

Same as NA but intake air still need longer time to reach cylinder since need to travel a long path. Won't that somewhat affect throttle response compared to a true NA?