Please don't laugh @ me

[VR4Kaos]

i know you all gonna think im really dumb now but what the hell if you dont ask you will never know i was told once by some weird guy lol
how dose a the twin turbo work i know with a single you reach 300rpm approx and the turbo kicks in
well it feels bout the same on the vr4 but when dose the 2nd turbo kick in or dose it work together
btw remember dont laugh at me dumbness ...pmsl

[peter thomson]

They both work together karl

[Turbo_Steve]

As Peter say, Karl, it's a V6 with a turbo on each side, rather than them working sequentially.

And strictly speaking, a turbo doesn't "kick in" either - they work all the time: they're always spinning away happily.

The "kick in" you refer to is when they enter their "efficiency" zone.

Imagine trying to blow a water droplet across a table using a straw. You can keep blowing gently, but that water droplet will never move. You can blow harder and harder, but there is a certain point where that droplet will move.

It's a rubbish analogy, but it gives you an idea what's going on....the air is flowing all the time, the turbos are turning, but it's not until it starts flowing at a certain rate that the engine produces enough gas to spin them faster to produce more pressure to produce more gas to sping them faster to produce more pressure to produce....etc.

[Roberto]

Don't feel dumb at all Karl.

Asking questions is something everyone has to do.
It's one of the best ways to learn, sometimes, you can search and search and never find the answers to the simplist of questions.

[VR4Kaos]

thanks for all the replys steve your water explanation is understandable even @ my iq level thanks.
so do all twin tubs work this way do they :)

[Atik]

Not all work this way. Some are sequential like the Legacy GTB and they 'kick' in one after the other.

[VR4Kaos]

thought as much think them runnin parraell is a much better idea presume it will be much smoother gradual excelleration vr4 are a bit quicker than the subs aint they ?

[Atik]

Its an age-old debate. I personally think the VR4 has the allround stock VS stock advantage. The Legacy is 'apparently' easier to get tuning parts so a modded one could be much more advanced than a modded VR4. That said, a well modded like-for-like VR4 VS GTB would still be very close. I would still give it to the VR4 though :D

And yes, having both turbos run same time means the power delivery is smoother. The Legacy is known to have the VOD (Valley of Death) where the wait between the turbos feels like you are driving a 1.1 litre Ford Fiesta!

[martin_y]

RX-7 has sequential, too. I liked it, as it gave a lot of torque at low down revs, where a rotary lacks a bit. Yes there was a dip in power as the 2nd turbo is "added" to the 1st turbo's boost, around 4500 rpm.

Our cars seem to have enough torque in the range where you normally drive without sequential.

[kinger]

Im not sure about that, my Legnum is pretty standard only got an exhaust and panel filter at the moment, and my mate has a pretty standard Legacy GTB, same just an exhaust and cone filter and i kick his ass all day long, off the lights, rolling start in the twisty's everywhere and it really gets to him cos its newer and he paid a lot more for his than i did.

[VR4Kaos]

so glad i bought a VR4/rally

[Turbo_Steve]

If his is one of the newer legacies, then it will be heavier than the VR4, unfortunately. And the Valley of Death isn't that bad on the standard car, but makes tuning them a pigging nightmare! You can do it, but getting a smooth transition....hmm..not something I'd like to try.

It's easier, apparently on the RX7s due to their excellent setup, and the fact that the rotary seems to spit out hot gas like it's going out of fashion!

[Subaru ETA]

RX-7 has sequential, too. I liked it, as it gave a lot of torque at low down revs, where a rotary lacks a bit. Yes there was a dip in power as the 2nd turbo is "added" to the 1st turbo's boost, around 4500 rpm.

Our cars seem to have enough torque in the range where you normally drive without sequential.

yup onthe RX-7s the set up works very well. you dont really notice them cwitching over. you get more torque through more of the power band making them fun in the wet :D

[waxer]

Most tuners seem to ditch the sequential turbos and go for one big one, for max top-end power.
My brother's just bought an RX-7 that's been modded in Japan. It has one huge big turbo that's said to be good for 1000hp, but it's currently boosting at 1.1bar, and producing 350-400. We're not sure how quick it really is, cos he's still a bit scared of the back axle, which is a "locking diff". But it's an awesome motor, seems to pull as well as a Legnum up to 5000rpm, then just go mental up to about 7000.
But totally impractical as a daily driver, he's just going out in it on Sundays at the moment.

[HOODY]

Don't feel dumb at all Karl.

Asking questions is something everyone has to do.
It's one of the best ways to learn, sometimes, you can search and search and never find the answers to the simplist of questions.

I second that, ive asked many many many many many many questions... and I thank you all for being so helpful. Ive had my leg for a year now and still didnt know the turbo answer. was a Good read ^^^^

[HOODY]

Im not sure about that, my Legnum is pretty standard only got an exhaust and panel filter at the moment, and my mate has a pretty standard Legacy GTB, same just an exhaust and cone filter and i kick his ass all day long, off the lights, rolling start in the twisty's everywhere and it really gets to him cos its newer and he paid a lot more for his than i did.

hahahahahaha

[bradc]

Steve, which Legacy are you talking about exactly?

The sleekest shape were a bit lighter, 1500kg for a manual one versus 1530kg for a VR-4

http://www.goo-net.com/catalog/SUBARU/LEGACY_TOURING_WAGON/10047705/index.html

The new ugly ones are 1520kg:

http://www.goo-net.com/catalog/SUBARU/LEGACY_TOURING_WAGON/10055395/index.html

And the best Legacy of all time is 1520kg:

http://www.goo-net.com/catalog/SUBARU/LEGACY_TOURING_WAGON/10047861/index.html

As for power, VOD, and other crap, read this page http://www.clubvr4.com/forum/showthread.php?t=41054&page=7&highlight=legacy+owner

Note in particular my posts comparing power at the wheels of a stock VR-4 vs a stock Legacy and then a modified one of each. The VR-4 simply has a lot more power.

The one advantage that you have with a Legacy is that you can bin the entire twin setup and go with all of the piping from a single turbo Impreza fairly cheaply and end up with a much bigger turbo and a more reliable setup.

[Kieran]

Note in particular my posts comparing power at the wheels of a stock VR-4 vs a stock Legacy and then a modified one of each. The VR-4 simply has a lot more power.

/Puts on Batman theme tune...

Da-Da-Da-Da-Da-Da-Da-Da-DA-Da-Da-Da-Da-Da-Da-Da.... STAT MAN!!!:d

Brad, it's not always about the numbers... Remember the Legacy VS Legnum video on Youtube?

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

Here's a translation I found (on the Legacy forums, funnily enough), of the commentary...



The vid basically puts the Gen II Legacy GTB against the Legnum VR4 in two different arenas: a slalom based handling test course and a circuit 3 lap race.

On the offset slalom based course, the active yaw control allowed the Legnum to be more composed at 40mph through the slalom and the tight curve, and to handle braking from 60mph whilst turning with less rear end slide and more safer front end push. They found that the 100kg lighter 17 inch wheeled Legacy GTB handled the slalom well but could slide when provoked and could slide whilst braking and turning hard from 60mph. The Legnum's high-tech AYC allowed it to handle the course faster.

At the circuit, the Legacy was faster in a straight line and on turn-in than the Legnum, and despite not having AYC it was able to match the Legnum through the bends due to having Bilstein shocks and being 100kg lighter. The Legacy posted the faster time and beat the Legnum head to head.

The chase car - 250bhp Silvia S14 - could not keep up with either the Legacy or the Legnum.

FWIW, the BH5 has handling improvements over the BG5 - introduced two years into the life cycle of the Legnum. Furthermore, the auto VTD-AWD Legacys have an electronic torque split (the system used as the base for the Impreza STI DCCD) so the manual Legnum's AYC stability advantage is eroded when put head to head with a VTD-AWD Legacy.

[Turbo_Steve]

Not sure where you're getting those weights from, Brad. None of my legacies have weighed less than 1640Kg when I've weighed them.
Haven't weighed the VR4 yet - no plans to drag / track it.

[AlanDITD]

Very surprised the sivia couldnt keep up with either of them....kinda cool though!

[bradc]

It is indeed kind of funny that the S14 couldn't keep up :)

Kieran, I wonder if the extremely oil overfilled VR-4 was having power problems? The massive amount of smoke coming out on the track was from an excess amount of oil in the VR-4 engine bay.

The other thing is that if you look at the power figures from 5000rpm upwards which is the speed they would be driving at, the Legnum would be a lot quicker from 5000 to 6000rpm but from 6000rpm to 7000rpm and with the weight difference the Legacy could be a bit quicker right up at the top of the rev range.

Makes you wonder though how much different it would be if Mitsi didn't put those stupid 205/55/16 wheels on the stock cars! Imagine if Mitsi had put EVO 5 wheels on them with 225/45/17 tyres and Bilstein shocks.

[Kieran]

Kieran, I wonder if the extremely oil overfilled VR-4 was having power problems? The massive amount of smoke coming out on the track was from an excess amount of oil in the VR-4 engine bay.

Ummm... What?! :inquisiti

[bradc]

I remember reading in another translation that the oil coming out of the Legnum was due to being massively over filled with engine oil.