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Technical turbo engines 101

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Technical turbo engines 101

Zane

Zane

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Hi Everyone

Just purchased a Bravo t-jet sport, my first turbo charged engine. Just a few questions regarding the turbo. Is it true that you have to make the vehicle idle for a few minutes before switching off, and I'm not a guy that drives flat out so my turbo gauge always reaches 2 bars maybe 3. Am i hurting the motor by not driving it so that the gauge goes up all the way.

Sorry for the idiotic questions but you here all sorts of stories

Thanks in advance :worship:
 
You have to let the car idle a few seconds when you stop suddently after speeding, it's not something you need to think about very often unless you drive like a mad man.

There is no rule on how to drive regarding the turbo's maintenance. it's a reliable engine, you're not driving a 70's turbo. :)
 
Zane said:
Hi Everyone

Just purchased a Bravo t-jet sport, my first turbo charged engine. Just a few questions regarding the turbo. Is it true that you have to make the vehicle idle for a few minutes before switching off, and I'm not a guy that drives flat out so my turbo gauge always reaches 2 bars maybe 3. Am i hurting the motor by not driving it so that the gauge goes up all the way.

Sorry for the idiotic questions but you here all sorts of stories

Thanks in advance :worship:
Click to expand...

does it say anything in the vehicle handbook about how to operate the engine?

the T-Jet engine is a well proven and well developed unit that is also fitted to the Abarth 500 and Abarth Grande Punto so it's designed to be driven and driven hard!

Most turbo engines are run at a lower compression which means they are sluggish off boost; the bravo is the same compression as a regular normally aspirated engine with a turbo on top
This means that the car performs ok even without the turbo and if you want more power the car will respond

There is no need to wait for ages idling after driving the car, you only have to do this on cars like evos which have huge turbos that get red hot

Enjoy learning the car and dont be afraid to use full boost :devil:
 
The handbook for the T-Jet does state something about letting the car idle befoer switching off after "vigorous driving" (i'm sure thats the term it uses lol).

If you have driven "off boost", ie below about 3000rpm you will be fine and dont need to let it idle. If you have been driving like a mad man, but drive off boost for a while before stopping the car you should also be okay as far as I believe.

The reason you would need to let the car idle after driving "vigorously" is to allow the engine and oil to cool down...but not being a mechanic I'm not entirely sure why haha!
 
If the turbo is red hot, and you just stop, you will loose the circulation of the coolant, i.e. oil. So you'll cook the oil and bearings and seals............
 
Pretty much what people have said before.

Just dont drive like a crazy fool until the engine has started to warm up and just calm things down a little the last minute of your journey (y)
 
The manual:
"STOPPING THE ENGINE
Turn the ignition to STOP while the engine is idling.
IMPORTANT After a taxing drive, you should allow the engine to “catch its
breath” before turning it off by letting it idle to allow the temperature in the engine compartment to fall."
 
Slightly off topic but is there a big reduction in fuel consumption when driving on boost?

Im imagining it to be like 1.4 mpg off boost and 2.0 mpg when on boost.
 
colin79666 said:
The manual:
"STOPPING THE ENGINE
Turn the ignition to STOP while the engine is idling.
IMPORTANT After a taxing drive, you should allow the engine to “catch its
breath” before turning it off by letting it idle to allow the temperature in the engine compartment to fall."
Click to expand...

I love these translated instructions :D
 
I thought i would put my 2p`s worth in after reading some pretty bad advice having been involved with/building turbo engines for 10+ years.

For a start, the t-Jet (9.8:1CR) does NOT run the same compression as the non turbo version (11:1CR), virtually all engines fitted with a turbo have to run a lower compression ratio in order to prevent meltdown via detonation. You can run a turbo on a standard CR engine if the turbo pressure is kept to a very small level OR the engine is built like a tank and the spark pattern modified.

If the guage is reading 2 to 3 bar (29.40 to 44.10PSI) then the guage is obviously broken or, if you are running this pressure the engine wouldnt last long, these boost pressures are massive and rarley run by even the mega powered cosworths/Evos etc, these kind of pressures would equate to circa 300BHP+.

The idling before shutdown should in my opinion be a given, whether you have given the car a thrashing or not, idling before shutdown allows the impellers of the turbo to return to their lowest RPM so that they dont continue spinning when the oil supply has stopped.
Same deal when giving the car some beans from cold, as soon as the water temperature reads `normal`, the oil temperature isnt necessarily at its operating temperature when the water is, try fitting a oil temp guage and you would be very supprised. Therefore, refrain from thrashing the car until the oil temperature has stabilised, a good 10 mins after the water has guage reads normal. This is good practice when owning a turbo engined car along with oil changes between intervals, given the cost of turbos it is well worth taking good care. I owned a RS Turbo many moons ago, the turbo lasted well in excess of 100k being run at more than twice the original boost presseure and a few trackdays thrown into the mix, only because of all the above.
 
Lloydy,

I think when the OP said it reaches 2 bars and sometimes 3, I am assuming he means the bar chart graph thing showing Oil pressure on the digital screen beneath the speedo on the T-Jet.

Just saying...
 
9.8:1 is a high cr for a turbo engine, hence it is in quite a high state of tune and needs iridium plugs. The goal was to minimise turbo lag on an engine designed to be economical off boost. It is a low boost engine with a small turbo.
But yes 10% less than the nasp 1368 engine which is above average cr from my understanding, 9.81 being a common nasp cr?

Lloydy19880 said:
I thought i would put my 2p`s worth in after reading some pretty bad advice having been involved with/building turbo engines for 10+ years.

For a start, the t-Jet (9.8:1CR) does NOT run the same compression as the non turbo version (11:1CR), virtually all engines fitted with a turbo have to run a lower compression ratio in order to prevent meltdown via detonation. You can run a turbo on a standard CR engine if the turbo pressure is kept to a very small level OR the engine is built like a tank and the spark pattern modified.

If the guage is reading 2 to 3 bar (29.40 to 44.10PSI) then the guage is obviously broken or, if you are running this pressure the engine wouldnt last long, these boost pressures are massive and rarley run by even the mega powered cosworths/Evos etc, these kind of pressures would equate to circa 300BHP+.

The idling before shutdown should in my opinion be a given, whether you have given the car a thrashing or not, idling before shutdown allows the impellers of the turbo to return to their lowest RPM so that they dont continue spinning when the oil supply has stopped.
Same deal when giving the car some beans from cold, as soon as the water temperature reads `normal`, the oil temperature isnt necessarily at its operating temperature when the water is, try fitting a oil temp guage and you would be very supprised. Therefore, refrain from thrashing the car until the oil temperature has stabilised, a good 10 mins after the water has guage reads normal. This is good practice when owning a turbo engined car along with oil changes between intervals, given the cost of turbos it is well worth taking good care. I owned a RS Turbo many moons ago, the turbo lasted well in excess of 100k being run at more than twice the original boost presseure and a few trackdays thrown into the mix, only because of all the above.
Click to expand...
 
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