Turbos that spool at rev

[tybrenis]

Hey guys,

I've noticed that some cars, like Jetta's or SRT-4s for example, will spool the turbo and built boost even when the car isn't in gear. I heard a video of a jetta with no exhaust and it sounded like a turbo diesel truck going up a hill without ever even leaving his driveway. Our car only builds boost under heavy throttle, as you all know. Just wondering the difference here and why that difference has been built into different cars.

Also, I would like to know if there is any way to make the turbo sound a bit louder? I love hearing that spool up sound!

 

[SeR_Cyclops]

I think that even SRTs wont boost in neutral, I think they must be under a load (Moving) to boost.

 

[dandan2]

it coulda been a tdi jetta! i have a neiber with a built on and when u rolls down the street i can hear his turbo spooling the whole time! and its because their turbos are tiny!

 

[HondaEat-R]

I'd say when it comes to boosting w/ no load, the size of the motor is more relevant than the turbo.

 

[anarchistchiken]

Negative, engine size doesnt matter, only turbo characteristics (size of housing & design of the fins mainly) factor into spool speed. Like the guy who cant speak English from Texas said, Jettas and GTI's (older ones at least) use a tiny tiny turbo called a k-51 or something like that. The inlet is about the size of a 50 cent piece, it's pretty ridiculous. The fact that all the cars exhaust must flow through that tiny housing makes the turbo spool at even the slightest blip of the throttle, but I've never seen any car build boost at idle.

If you want a louder turbo, get an intake or exhaust, or just take one of your O2 sensors out and leave the hole open in the exhaust, that will liven up your morning commute.

 

[HondaEat-R]

1) The VW turbo you're talking about is a KKK K03 turbocharger.

2) I hope you're kidding when you say engine size does not affect spool up. We all know that A/R sizes are relevant, however, what you're saying is that if I took a T25 and noted the spool characteristics while on a 2.0L, then put the same turbo on a 6.0l motor and noted the characteristics they'd be the same.... ? Wrong

This is very very basic: More displacement equals more exhaust gasses. Exhaust gases are what primarily spools your turbo.

 

[mazdafreak7]

its a combo of enigine size and turbo A/R the car is most likely not building boost without driving unless he has a two step, another thing that makes a turbo way louder is a anti surge compressor housing, i went from a T04R with standard housing to a T04Z with anti surge and the anti surge is 5 times as loud and it has the "semi truck" spool sound under light throttle, and this is a 67mm turbo with 1.15 AR exhaust housing, turbo is on a built RX7

 

[tybrenis]

I'm not talking about building boost. I'm talking about passing air through the turbo when you rev it and hearing that "spool" sound. The video in question was a 1.8t jetta, not a diesel, and it was whirring away like a semi truck. I guess it just has to do with back pressure in your exhaust. No exhaust, nothing to stop you from hearing the turbo spinning.

 

[HondaEat-R]

The Jetta was prob running open downpipe, which basically reduces back-pressure, and also allows you to HEAR the turbo spool much more. Even just changing from a thick cast downpipe, to a thinner walled stainless downpipe will produce more noise. It will resonate more sound easily.

You could just make you AFR rich as s*** on idle, and rev it up. The exhaust air will be saturated w/ fuel and will spin the exhaust turbine much more easily.... not suggested though, lol.

 

[mazdafreak7]

yea an open downpipe is prob what your hearing, ive heard that alot on srt-4s

 

[pliskin679]

my buddy has a evo and it will build boost sitting in neutral by just revving it, and its got a pretty big turbo... a FP-red. it all depends on how the turbo is build, and how smooth it is.

http://www.youtube.com/watch?v=CYopWiYr5tA

just like that

 

[pliskin679]

and a open DP lets you hear it alot more

 

[perfectblend]

could the turbo have ball bearings!?

 

[foxracer]

In that video hes not building any boost, take your j pipe off and rev it alittle it will do the same thing.

 

[SeR_Cyclops]

Yeah he is not building boost you just hear the turbo, with my cutout open it sounds similar.

 

[MAZDA_SPEED]

1) The VW turbo you're talking about is a KKK K03 turbocharger.

2) I hope you're kidding when you say engine size does not affect spool up. We all know that A/R sizes are relevant, however, what you're saying is that if I took a T25 and noted the spool characteristics while on a 2.0L, then put the same turbo on a 6.0l motor and noted the characteristics they'd be the same.... ? Wrong

This is very very basic: More displacement equals more exhaust gasses. Exhaust gases are what primarily spools your turbo.

x2, Ive owned a 1.8T. k03s

 

[squire0311]

lol the fp red isnt that big! its barley bigger than a stock evo 8turbo!

 

[kyle's protege5]

I dont know what your guys problem is, mine will spool and pop off all day when punching the gas in neutral (cabpatch)

 

[WIMSPWI]

a vw commonly runs a k03 or k04 u tards...and why'd u buy ur msp? u thought cause it was turbo itd be fast? please...