Turbo Size

[beerad]

Hey guys just wondering if your turbo is spooling up 15psi of boost and its just a shitter factory turbo then you switch to a ball bearing 1000hp beasty turbo and you still only run it at 15psi is the engine going to go any faster or is it just the delivery of the power that changes. cheeer

[shaggz]

that wont change wot will change is when yuou cum on boost and probably your tourqe patterns bigger turbo you devolp boost later in rev range generally but also generally they'll hold boost a bit better and can sustain higher boost levels sumone correct me if im wrong. but why would yuo wanna put a huge sucker on if yuo only gonna do street use if yuo dragging or circuit thats a different story

[CozmoNz]

Um... bigger turbos flow more air... boost pressure is this volume of air compressed.

so when the moron boyracers say *im running 9psi*.. thats nice darling, im running 4psi and flowing more air than you .

why is it that dragsters can run 6psi and run 7's? and the brat in the gtir runs 22psi and manages a 14.5 . AIR FLOW.

[EVLGTZ]

Would make a huge difference also in terms of flow. 15psi on one turbo can be vastly different to 15psi on another turbo.

Different turbos can flow different amounts so of course this will have an effect on how hard the motor is pushed.

[beerad]

so break it down for me boys, im knew to the turbo thinggy

[10k 20v]

it all comes own to efficiency, a larger turbo will produce lower charge temperaures at the same boost levels as a smaler turbo, so therefore producing a denser air charge, not always the case as some smaler turbos can be bloody efficient

[Loudtoy]

it all comes own to efficiency, a larger turbo will produce lower charge temperaures at the same boost levels as a smaler turbo, so therefore producing a denser air charge, not always the case as some smaler turbos can be bloody efficient

As can be seen on my fiance's starlet, running a ct9 at 12psi was average, didn't like running it that high but due to exhaust and other things thats the lowest i could get it.
It now has a tdo4 on it, doesn't boost quite as qiuckly, ct9 had full boost by 2.3k and tdo4 doesn't have full boost till 3.3k but it's just about as fast off boost as it was with the ct9 on boost. This is because of the air volume that is going through, even off boost the tdo4 is flowing nearly the same vloume as the ct9 was on say 3psi.
Cause of this - heat.
Ever notice your car goes better on a cold night?? Colder denser air, bigger turbo on same boost generally equals this.

Hell that does't make any sense at all, hope i haven't confused you with it. With a bit of luck someone with better wording skils than me will translate this into usefull information!

[Dell'Orto]

Its a bit of a combination of what Jimmy was saying...a larger turbo can flow more air at a given rpm, with less shaft speed than a small turbo.
The slower the turbo is spinning, the cooler the air is, as its not being compressed as densely.
IE TD04 (GSR Lancer) vs T88 (Croydon drag GT-R)
The TD04 might be pushing 15psi of indicated boost pressure, but only flowing 400cfm with a shaft speed of 150,000rpm
The T88 could push 15psi, and flowing 900cfm with only 80,000rpm.

There are heaps of variables in it, but basically bigger turbo = more airflow = more power



These numbers are completely made up too btw, its just for comparison.

[Zero_Cool]

oo so that means that if i run 18psi on my td05 and my car doesn't blow up then i run a lets say t78 on 18psi my car would blow up? interesting

[Loudtoy]

Its a bit of a combination of what Jimmy was saying...a larger turbo can flow more air at a given rpm, with less shaft speed than a small turbo.
The slower the turbo is spinning, the cooler the air is, as its not being compressed as densely.
IE TD04 (GSR Lancer) vs T88 (Croydon drag GT-R)
The TD04 might be pushing 15psi of indicated boost pressure, but only flowing 400cfm with a shaft speed of 150,000rpm
The T88 could push 15psi, and flowing 900cfm with only 80,000rpm.

There are heaps of variables in it, but basically bigger turbo = more airflow = more power



These numbers are completely made up too btw, its just for comparison.

Aha i knew someone would come to the rescue, cheers brad i seemed to have some kind of mental block when i wrote that. Btw where did you guys get to last night, i showed up and there was no one there!

[Rollux]

As already stated, pressure is not a measure of volume.
As a real example, by car has enough fuel stock to cope with 14psi from my T25. When I put my GT28R on tho, it will only have enough fuel for about 8psi, but it will still make more power on 8psi on the GT28R because there is still more airflow and less heat.
Remember the compressor on the turbo is also a restriction in the inlet system, so the more efficient it is, the less of a restriction it becomes.

[Lunchie]

Its a bit of a combination of what Jimmy was saying...a larger turbo can flow more air at a given rpm, with less shaft speed than a small turbo.
The slower the turbo is spinning, the cooler the air is, as its not being compressed as densely.
IE TD04 (GSR Lancer) vs T88 (Croydon drag GT-R)
The TD04 might be pushing 15psi of indicated boost pressure, but only flowing 400cfm with a shaft speed of 150,000rpm
The T88 could push 15psi, and flowing 900cfm with only 80,000rpm.

There are heaps of variables in it, but basically bigger turbo = more airflow = more power



These numbers are completely made up too btw, its just for comparison.

Aha i knew someone would come to the rescue, cheers brad i seemed to have some kind of mental block when i wrote that. Btw where did you guys get to last night, i showed up and there was no one there!

how the F**K did u manage a 14.7 1/4mile with only 93kw?......and front wheel drive!!!

[Loudtoy]

how the F**K did u manage a 14.7 1/4mile with only 93kw?......and front wheel drive!!!

Light weight, quite sticky road tires, the ability not to just keep my foot up it but feather the throttle when it wants to get a wheel up and some decent springs.
Btw there are a few other 14.8's and 9's with higher trap speeds to back it up and all with an open diff.
Should be a few more specs like 60 ft times i think in the profiles part

Edit Apparently i didn't put it up but the 60ft time was 2.02 and the half track was 9.0 at some speed or other i think it was 73mph??

[Dell'Orto]

how the F**K did u manage a 14.7 1/4mile with only 93kw?......and front wheel drive!!!

Mental driver

[Lunchie]

how the F**K did u manage a 14.7 1/4mile with only 93kw?......and front wheel drive!!!

Light weight, quite sticky road tires, the ability not to just keep my foot up it but feather the throttle when it wants to get a wheel up and some decent springs.
Btw there are a few other 14.8's and 9's with higher trap speeds to back it up and all with an open diff.
Should be a few more specs like 60 ft times i think in the profiles part

Edit Apparently i didn't put it up but the 60ft time was 2.02 and the half track was 9.0 at some speed or other i think it was 73mph??

so what sort of time would you expect a 130kw (atw) example could do (1994 gt apex) with well sorted suspension?

[jondee86]

Hey guys just wondering if your turbo is spooling up 15psi of boost and its just a shitter factory turbo then you switch to a ball bearing 1000hp beasty turbo and you still only run it at 15psi is the engine going to go any faster or is it just the delivery of the power that changes.

The short answer is, that no matter what size turbo you are running, if it is
limited to 15 psi, you make the same power.

The 15 psi is the pressure difference from the inlet manifold to the
outlet manifold with the valves acting as a restrictor plate. And flow
is the result of pressure x area. So if you want more flow you can
increase the size of restrictor plate (bigger valves), or increase the
pressure difference (boost).

Looking at it another way, pressure is the result of flow divided by
area. It's not the turbo that sets the pressure, but the size of the
restrictor plate (or orifice) that it is blowing through.

Don't believe me ?? Then how much pressure do you have in a
garden hose until you put your thumb over the end of it ???

If you have 15 psi, then you have 15 psi. It doesn't matter if it comes
from the meanest mother of all race turbos, an electric fan, a steam
powered compressor or a choir of angels farting in unison... all you
have is 15 psi

Cheers...... jondee86

[EVLGTZ]

so what sort of time would you expect a 130kw (atw) example could do (1994 gt apex) with well sorted suspension?

Well I ran a 13.82 with 131kw at wheels in my levin a few years ago. That should give some indication.

[vvega]

Hey guys just wondering if your turbo is spooling up 15psi of boost and its just a shitter factory turbo then you switch to a ball bearing 1000hp beasty turbo and you still only run it at 15psi is the engine going to go any faster or is it just the delivery of the power that changes.

The short answer is, that no matter what size turbo you are running, if it is
limited to 15 psi, you make the same power.

The 15 psi is the pressure difference from the inlet manifold to the
outlet manifold with the valves acting as a restrictor plate. And flow
is the result of pressure x area. So if you want more flow you can
increase the size of restrictor plate (bigger valves), or increase the
pressure difference (boost).

Looking at it another way, pressure is the result of flow divided by
area. It's not the turbo that sets the pressure, but the size of the
restrictor plate (or orifice) that it is blowing through.

Don't believe me ?? Then how much pressure do you have in a
garden hose until you put your thumb over the end of it ???

If you have 15 psi, then you have 15 psi. It doesn't matter if it comes
from the meanest mother of all race turbos, an electric fan, a steam
powered compressor or a choir of angels farting in unison... all you
have is 15 psi

Cheers...... jondee86

so whats the diffeance in desity from air that is 15psi @100 dgrees c
and air that is 15 psi @ 20 dgrees
:d
wanna fine out how much of a differance to air volume a little bit of heat can make
tir this

blow up a baloon
hold a lighter under it ...see what happens

if you can see much differance with a tiny flame barly varing heat over such a small volume of air ..imagine the differance over the period of engine flow for say 1 minuite
at 8000 rpm on a 1600 you divde 8000 by 4 = 2000 x cc's....= air moved at atmospheric wot position

its a lot of air....
you all are getting it right....kinda you just need to pool your answeres togeathier and see what attually happening

v

[Dr-X]

I Think he's talking about equal conditions. Of course heat is going to make a difference, but we're comparing turbo's under the same conditions, assumingly. Good write up jondee86.

[Andy from the block]

The short answer is, that no matter what size turbo you are running, if it is
limited to 15 psi, you make the same power.

If you have 15 psi, then you have 15 psi. It doesn't matter if it comes
from the meanest mother of all race turbos, an electric fan, a steam
powered compressor or a choir of angels farting in unison... all you
have is 15 psi

So without taking heat into account, you think all turbos at 15psi would
flow the same volume of air in a given space of time at the same rpm?

If this is true, then it contradicts what people earlier said about larger
turbos flowing more air at the same psi.
If Jondee86 is correct in his same psi same flow arguement, does that
mean the only benefit a larger turbo has at the same psi, would be heat
efficiency? (assuming all other variables are constant, ie: piping size,
port size, intake manifold etc)???

As already stated, pressure is not a measure of volume.
As a real example, by car has enough fuel stock to cope with 14psi from my T25. When I put my GT28R on tho, it will only have enough fuel for about 8psi, but it will still make more power on 8psi on the GT28R because there is still more airflow and less heat.

So if what I understand of Jondee86's arguement is correct, Rollux is
making more power and using more fuel , not because of increased flow
of air volume, but purely on heat efficiencies of the larger turbo?