boost return, return............

[newt]

im thinking of refiting my boost return pipes, when i got my g40 they were not fitted ,luckily i had a spare pair from years back when i removed them from a previous g, ( keeping things always come in handy lol they must of been in the atic for 6 years lol) problem being the breather pipe has been cut off as i used to run a catch tank and the boost return pipework before completely removing the pipework
 what are peoples views on refiting it , i dont need the blow off noise , the charger and tooth belt whine is enough
i realise that also the air recirculating into the charger is walm , is this really a problem
i know jabba "like" to keep the breather setup, and others say dont breath into the charger.....
ps
 any one got an unmolested boost pipe ? the one with the breather pipe intact.

[The Duck]

What makes you think the air going through the G-Lader is warm? No boost pressure = no temperarture rise.

[Justin14100]

What makes you think the air going through the G-Lader is warm? No boost pressure = no temperarture rise.

You do make a good point here - people always go on about the "hot oily air" that goes into the engine. yeah. its hot. then it goes back into the charger. then into the intercooler. and cooled. and before its closed off there is almost no load on the air anyway.

[newt]

simple
the air with the boost return pipe removed gets vented to atmosphere so lets say that air at idle is 25 degrees
the air with the boost pipes in place going back into the charger will of gone through the heat soaked rockercover so would of risen a coupe of degrees potentialy at idle this process will get worse as the air temp goes up whilst on boost (compressed air is hotter)
there for the air is cooler with boost pipe removed the difference may only be a degree or two. but its not gonna run cooler with the recirculating pipework thats for sure
as for cooling the air, lets say for example the compressed "on boost" air in the intercooler with no boost return is going in at 45 degrees ad coming out at 25 degrees thats a drop of 20 degrees , with the boost return pipes in place and lets say that the returned air has picked up a couple of degreed of heat from the rocker cover is going in at 47 degrees , unless the intercooler surface area is greater its not going to come out at 25 degrees, i could be wrong with the "potential " heat that could be absorbed by returning through rocker cover

ps im not worried about the above , i dont think it will be "human ly" noticable on the road , it may be picked up in control conditions ie rolling road

[hayesey]

Air pressure in the boost return pipe isn't zero, there is a pressure drop when the BRV opens but it's not to relative zero as the charger is pushing air round the boost pipes and brv pipes,the whole lot has some pressure which isn't seen on a boost gauge because that is under the throttle plate.

This is my understanding of it anyway, someone should put a temperature probe into the brv pipe and measure what's happening

[Jezza-7]

From personal experience the air is warmer with the return on as when i was driving on the motorway having done 150 miles off boost, i pulled over one day and thought i would see how hot my alloy boost pipe was. It was very hot and i didnt expect it to be as hot as that. Obviously the air just keeps getting reculated over and over again. Knowone drives on boost all the time so it will get hotter and hotter. Unless you have a front mount intercooler it might not be as hot?

Then with the boost return removed i did the same jurney off boost, and when i pulled over the boost pipe was the very cold. Cause the air wasn't reculating over and over again, the only air coming into the charger is the air from the atmosphere and colder than the warm air that would be recualting with the boost return on.

I think that proves a good point in my opinion? But im not sure?

[newt]

From personal experience the air is warmer with the return on as when i was driving on the motorway having done 150 miles off boost, i pulled over one day and thought i would see how hot my alloy boost pipe was. It was very hot and i didnt expect it to be as hot as that. Obviously the air just keeps getting reculated over and over again. Knowone drives on boost all the time so it will get hotter and hotter. Unless you have a front mount intercooler it might not be as hot?

Then with the boost return removed i did the same jurney off boost, and when i pulled over the boost pipe was the very cold. Cause the air wasn't reculating over and over again, the only air coming into the charger is the air from the atmosphere and colder than the warm air that would be recualting with the boost return on.

I think that proves a good point in my opinion? But im not sure?

yes it certainly confirms my thought, good example
 

[Justin14100]

From personal experience the air is warmer with the return on as when i was driving on the motorway having done 150 miles off boost, i pulled over one day and thought i would see how hot my alloy boost pipe was. It was very hot and i didnt expect it to be as hot as that. Obviously the air just keeps getting reculated over and over again. Knowone drives on boost all the time so it will get hotter and hotter. Unless you have a front mount intercooler it might not be as hot?

Then with the boost return removed i did the same jurney off boost, and when i pulled over the boost pipe was the very cold. Cause the air wasn't reculating over and over again, the only air coming into the charger is the air from the atmosphere and colder than the warm air that would be recualting with the boost return on.

I think that proves a good point in my opinion? But im not sure?

Seems odd though cause its going to be cooled anyway over and over too. driving off boost my intercooler gets cold. it feels cold, so surely as its being re-cooled anyway its not a major issue. and as soon as you go on boost the BRM shouldn't make any difference at all cause it wont be taking any air from the recirculation pipes at all

[newt]

it wont make any difference when on full throttle, correct, but you drive more off boost as you do full throttle surely?

think maybe its worth actually measuring the air temp in the pipework with and without boost return pipes, it would have to be done in a "off boost" mode , as this is when the difference should be

[Jezza-7]

From personal experience the air is warmer with the return on as when i was driving on the motorway having done 150 miles off boost, i pulled over one day and thought i would see how hot my alloy boost pipe was. It was very hot and i didnt expect it to be as hot as that. Obviously the air just keeps getting reculated over and over again. Knowone drives on boost all the time so it will get hotter and hotter. Unless you have a front mount intercooler it might not be as hot?

Then with the boost return removed i did the same jurney off boost, and when i pulled over the boost pipe was the very cold. Cause the air wasn't reculating over and over again, the only air coming into the charger is the air from the atmosphere and colder than the warm air that would be recualting with the boost return on.

I think that proves a good point in my opinion? But im not sure?

Seems odd though cause its going to be cooled anyway over and over too. driving off boost my intercooler gets cold. it feels cold, so surely as its being re-cooled anyway its not a major issue. and as soon as you go on boost the BRM shouldn't make any difference at all cause it wont be taking any air from the recirculation pipes at all

Have you ever drove down the road for 10 mins, off boost then taken off the return pipe and felt the air? It is very warm.

The warm air will heat up the charger not to mention the heat from the engine/charger and the mount. If its a standard intercooler i dont think it will be as good for cooling as its not in the best postion. Also the intercooler is close to the charger that will get warm after time. If you have a front mount yes it probably woudnt matter if you had it or not.

My standard i/c is made out of ally and that still got warm when i had the boost return on but now its alot colder with the return off.

At the end of the day its personal choice. Only way to tell it to measure temp after i/c with the return then once again with the return off.

[Justin14100]

it wont make any difference when on full throttle, correct, but you drive more off boost as you do full throttle surely?

think maybe its worth actually measuring the air temp in the pipework with and without boost return pipes, it would have to be done in a "off boost" mode , as this is when the difference should be

Well my intercooler gets cold as i said - newly compressed air is going to be warmer than the air that would heat up in the engine bay pipes - remember one pipe goes across the top of the radiator on the way to the throttle body so that wont help.

then again. i dont have much / any faith in the boost return mod. I know some people live by it but constant lube from the breather / quieter / how it was designed by VW. frequent oil / filter and air filter changes are key to a healthy charger. Saw someone claim an 8bhp increase after the Boost return mod but just cant see it tbh.

than again. (again ) others around here have more experience with it than I do!

[Jezza-7]

it wont make any difference when on full throttle, correct, but you drive more off boost as you do full throttle surely?

think maybe its worth actually measuring the air temp in the pipework with and without boost return pipes, it would have to be done in a "off boost" mode , as this is when the difference should be

Was writing mine as this post popped up, i agree with the driving off boost and with the air temp!

Plus i think you dont use as much fuel with the boost return off as fuel is 60% for cooling. If you have the boost return off, travelling a few long distance trips the engine wont get as hot as it would with the retun on. Maybe? I dont know?

[Jezza-7]

lol an 8bhp increase? Is that possible? Who said that?

I dont think that would be possible?

I do agree with what you say justin about the radiator and that, i guess the only way to benefit would be to get a front mount setup if you want a lilttle cooler air temp?

[Justin14100]

From personal experience the air is warmer with the return on as when i was driving on the motorway having done 150 miles off boost, i pulled over one day and thought i would see how hot my alloy boost pipe was. It was very hot and i didnt expect it to be as hot as that. Obviously the air just keeps getting reculated over and over again. Knowone drives on boost all the time so it will get hotter and hotter. Unless you have a front mount intercooler it might not be as hot?

Then with the boost return removed i did the same jurney off boost, and when i pulled over the boost pipe was the very cold. Cause the air wasn't reculating over and over again, the only air coming into the charger is the air from the atmosphere and colder than the warm air that would be recualting with the boost return on.

I think that proves a good point in my opinion? But im not sure?

Seems odd though cause its going to be cooled anyway over and over too. driving off boost my intercooler gets cold. it feels cold, so surely as its being re-cooled anyway its not a major issue. and as soon as you go on boost the BRM shouldn't make any difference at all cause it wont be taking any air from the recirculation pipes at all

Have you ever drove down the road for 10 mins, off boost then taken off the return pipe and felt the air? It is very warm.

The warm air will heat up the charger not to mention the heat from the engine/charger and the mount. If its a standard intercooler i dont think it will be as good for cooling as its not in the best postion. Also the intercooler is close to the charger that will get warm after time. If you have a front mount yes it probably woudnt matter if you had it or not.

My standard i/c is made out of ally and that still got warm when i had the boost return on but now its alot colder with the return off.

At the end of the day its personal choice. Only way to tell it to measure temp after i/c with the return then once again with the return off.

The charger itself would heat up anyway - it is compressing air and produces quite a lot of heat - some slightly warmer air coming back in wont make little / any difference to internal charger temperatures. there are some figures in a thread somewhere about intercoolers saying on boost at the charger outlet its pushing up to 100C and off boost it was a couple of degrees above ambient at the TB. think it was didnt have the recirc pipes though.

it wont make any difference when on full throttle, correct, but you drive more off boost as you do full throttle surely?

think maybe its worth actually measuring the air temp in the pipework with and without boost return pipes, it would have to be done in a "off boost" mode , as this is when the difference should be

Was writing mine as this post popped up, i agree with the driving off boost and with the air temp!

Plus i think you dont use as much fuel with the boost return off as fuel is 60% for cooling. If you have the boost return off, travelling a few long distance trips the engine wont get as hot as it would with the retun on. Maybe? I dont know?

not sure how much it would effect fuel economy. but im sure as i said a few degrees warmer air isnt going to make the engine / charger run substantially hotter - you gotta remember inside the block there is huge amounts of heat energy being produced.

also it was on club polo someone claimed it was done on a RR. will find it for you.

[Jezza-7]

im thinking of refiting my boost return pipes, when i got my g40 they were not fitted ,luckily i had a spare pair from years back when i removed them from a previous g, ( keeping things always come in handy lol they must of been in the atic for 6 years lol) problem being the breather pipe has been cut off as i used to run a catch tank and the boost return pipework before completely removing the pipework
 what are peoples views on refiting it , i dont need the blow off noise , the charger and tooth belt whine is enough
i realise that also the air recirculating into the charger is walm , is this really a problem
i know jabba "like" to keep the breather setup, and others say dont breath into the charger.....
ps
 any one got an unmolested boost pipe ? the one with the breather pipe intact.

Have you been on german ebay? Type in, polo Auftrieb Rohr. Might get something? I have one but im keeping it as i know there hard to get