Does yours make boost??

[michael a]

I have a td42 with a turbo on it, If i rev it in neutral it does not produce any boost maybe 1 psi if lucky. driving it makes 11-12psi no problems.

I was driving a mates car, It makes boost when revved in neutral.

So does yours? or do I have a problem ???

[HotFourOk]

Mine is the same, it will produce a couple of psi if revved in neutral.

It will make 11psi through gears, but the load on the motor is what creates more exhaust gas to spin the turbo.

You see some of the ricer boys going, revving it at lights, with their BOVs going off.... so some cars must make good boost in neutral.

[LuxyBoy]

It will make 11psi through gears, but the load on the motor is what creates more exhaust gas to spin the turbo.

That makes no sense to me. If you rev your vehicle be it petrol/deisel/car/4X4 to a certain rev it has a certain fuel/air mixture being burnt that creates a certain amount of exhaust gas; whether in gear or not it makes sense to me that it will always make the same amount of exhaust gases at that rev. (For every action there is an equal and opposite reaction)

Tell me if i am wrong but that sounds logical to me
Flame suit on

[pongo]

It will make 11psi through gears, but the load on the motor is what creates more exhaust gas to spin the turbo.

That makes no sense to me. If you rev your vehicle be it petrol/deisel/car/4X4 to a certain rev it has a certain fuel/air mixture being burnt that creates a certain amount of exhaust gas; whether in gear or not it makes sense to me that it will always make the same amount of exhaust gases at that rev. (For every action there is an equal and opposite reaction)

Tell me if i am wrong but that sounds logical to me
Flame suit on

Most diesels have a govenor, which will allow full fuel under load only and also limit the max RPM

most lawnmowers jhave em as well, If you know how to bypass it you can really cut the tall grass

[DanielS]

It will make 11psi through gears, but the load on the motor is what creates more exhaust gas to spin the turbo.

That makes no sense to me. If you rev your vehicle be it petrol/deisel/car/4X4 to a certain rev it has a certain fuel/air mixture being burnt that creates a certain amount of exhaust gas; whether in gear or not it makes sense to me that it will always make the same amount of exhaust gases at that rev. (For every action there is an equal and opposite reaction)

Tell me if i am wrong but that sounds logical to me
Flame suit on

No load mate,

if you keep an engine at 2100rpm in neutral for 1 hr, then keep the same engine at a steady crusie at 2100rpm for the same time it will use more fuel. that is engine load, and engine load = fuel burnt= boost.

Daniels

[DanielS]

oh back on subject...

my old turbo system didn't make boost free reving,

and my new system see a slight twich in the needle under fully floored, then zero..

once again there is no load on the engine free reving .

Daniels

ps ( i love friday lunch time pints )

bye

[KiwiBacon]

That makes no sense to me. If you rev your vehicle be it petrol/deisel/car/4X4 to a certain rev it has a certain fuel/air mixture being burnt that creates a certain amount of exhaust gas; whether in gear or not it makes sense to me that it will always make the same amount of exhaust gases at that rev. (For every action there is an equal and opposite reaction)

Tell me if i am wrong but that sounds logical to me
Flame suit on

As already mentioned, a diesel injection pump only puts in enough fuel to maintain the speed that your foot dictates.
With no load there's little fuel burnt and little exhaust heat.

When load is applied more fuel is injected which makes for much much hotter exhaust. Hotter exhaust has more volume so it spins the turbine and creates boost.

If you hold your engine at full rpm with no load you'll get some boost just because of the exhaust volume you're poking through it, but it's a terrible thing to do to an engine.

[michael a]

ok so i get that there is no load when reving in neutral but why does my mates car make full boost when revving it??

My egt sits on under 100*c at idle Where do most diesels sit at?

[stool]

It comes down to useing the correct turbo for a engine size

My ball bearing garrett turbo made around 5psi at 3000rpm free spinning with intercooler and 3" exhaust On a 2.8t dieael

[KiwiBacon]

ok so i get that there is no load when reving in neutral but why does my mates car make full boost when revving it??

My egt sits on under 100*c at idle Where do most diesels sit at?

My diesel EGT is off the bottom of the dial when cold, when fully warm is about 170 deg C.
What car has your mate got? Is it petrol?

[RAY185]

ok so i get that there is no load when reving in neutral but why does my mates car make full boost when revving it??

My egt sits on under 100*c at idle Where do most diesels sit at?

What sort of vehicle does your mate own?

[chunderlicious]

rev it in bursts... dont hold the revs, floor it then let off floor then let off like they do when showing off at the lights. this will get the air flowing fast enough that itll boost up the car.... watch kym bolton at 8 day 2006 and it is what he does. rev rev rev drop clutch and he had full boost and made it up the hill.

petrols do the same thing. you just need to let it sit at higher revs for a few seconds and itll boost if it has the correct size turbo. the engine load is what gets it spinning. the extra exhaust produced by the stress of load. by revving then letting it off it takes it back to idle which puts a bigger load on the engine to spin it faster.

always worked for me and everyone else i saw in petrol and diesel.

[Patroler]

rev it in bursts... dont hold the revs, floor it then let off floor then let off like they do when showing off at the lights. this will get the air flowing fast enough that itll boost up the car.... watch kym bolton at 8 day 2006 and it is what he does. rev rev rev drop clutch and he had full boost and made it up the hill.

petrols do the same thing. you just need to let it sit at higher revs for a few seconds and itll boost if it has the correct size turbo. the engine load is what gets it spinning. the extra exhaust produced by the stress of load. by revving then letting it off it takes it back to idle which puts a bigger load on the engine to spin it faster.

always worked for me and everyone else i saw in petrol and diesel.

I'll second that, also a lot comes down to turbo size, I had a bluedird with an L20 and T04 and it would make stuff all boost revving it in neutral, didn't event make much in first - maybe 10psi by the time it revved out, but as the motor loaded up in 2nd and 3rd it'd hit 20-23psi.
Also had a TX3 laser 1.6l with small rhb5 IHI turbo and it would do the bov thing if it was revved quickly in neutral would get upto 3-4psi (maxed out at 11 - wastegate worked on this one).

[michael a]

My maye has a TD42 but gu standard turbo with 3in dump pn it. I havce the DTS kit with mitsu turbo on it.

What patroler wrote is the same on my car.

If the waste gate has a hole in would this cause a problem like this jsut an Idea.

[Tapage]

A stock HDJ-80 wth factory CT-26 turbo make boost at neutral .. if you disconect the wastegate can go up to 16 psi or so ..

My 2H aftermaket turbo don't make more than 5 PSI in neutral .. even wth a lot's of fuel that have injected by electric pump .. making 14 PSI with load ..

[KiwiBacon]

rev it in bursts... dont hold the revs, floor it then let off floor then let off like they do when showing off at the lights. this will get the air flowing fast enough that itll boost up the car.... watch kym bolton at 8 day 2006 and it is what he does. rev rev rev drop clutch and he had full boost and made it up the hill.

If I hold the engine at 1500rpm in neutral the boost gauge still shows nothing. But if it's in second and I ease the clutch out it builds boost instantly to about 10psi if I keep the foot down.

Fastest way to launch by far, but it's gotta take it's toll on the driveline.

[me3@neuralfibre.com]

Petrol generally won't register boost in neutral, as boost gauge is after the throttle butterfly.
BOV is BEFORE the throttle butterfly. This restriction allows the limted gasflow put out by the turbo to be held back, creating pressure. Boost gauge before the throttle butterfly on petrol would register.
Your diesel swallows all the air as fast as the turbo pushes it, there is no butterfly restriction = no boost. Gasflow yes, but no boost.

Boost is a result of the turbo pushing against something, engine, butterfly etc.

Paul

[KiwiBacon]

Petrol generally won't register boost in neutral, as boost gauge is after the throttle butterfly.

Yes they will, you have to open the throttle to rev the engine.

[me3@neuralfibre.com]

Petrol generally won't register boost in neutral, as boost gauge is after the throttle butterfly.

Yes they will, you have to open the throttle to rev the engine. ;)

Assuming you aren't willing to bounce it on the rev limiter they generally won't make boost.

Is that better?

Anti lag makes good boost, you could fit that to fix the problem. Sounds way cooler than any p*ssant Blow Off Valve.

Paul

[HotFourOk]

Petrol generally won't register boost in neutral, as boost gauge is after the throttle butterfly.

Yes they will, you have to open the throttle to rev the engine.

Assuming you aren't willing to bounce it on the rev limiter they generally won't make boost.

Is that better?

Paul

Well, mine's a diesel with NO butterfly, and needs to rev a LOT to generate any boost in neutral..

[tna racing]

mines a gas powerd and it creats 9psi in nuetrul and 10 through the gears

[Tapage]

mines a gas powerd and it creats 9psi in nuetrul and 10 through the gears

Good point ..

I thought butterfly Diesels procude ( or at lease you can see in your boost gauge that in my case it's before the butterfly ) less boost than non butterfly Diesel at neutral ..