This looks interesting... V8 Caldina

[vvega]

ok lets lay off teh figuures and get the basics right

a equation of cfm and v.e gives you your power

so a small turbo may deliver 350 cfm to the engine at 14 psi

a larger turbo may deliver 350 cfm to the motor at 7

however the smaller turbo will suplly more power over teh total rev range

while the larger turbo will have a larger off boost hole

when you deside on a turbo you size it to your power requirements

if you was a 500 hp motor you get a 600odd cfm turbo
this gives you the best posible spool time and power from keeping in teh high effciancy range of teh turbo

if you oversize the turbos you will fall out of efftiancy in the lower range and perhaps even in your top boost figgure



psi is not relevant in a dissuccion about mating turbo's to engines
psi is liek cam duration
its speced to give you what you need

charge heat is not relevan
you size your intercoolers aproratly and make sure your turbo is still running in effiancy

all that is releanvt is your power aim
you size and build your engine to get the best possible power curve from that

thats where i think this has gone wrong
hes got good power
but IMO he could have got a far better power curve buy utaliing turbo's better suited to teh power figgure hes tring to obtain
im making teh asubtion its not over 500 hps simple because teh rest of the car sinply wont take it and it would take significant money to increase that

perhaps in the range of 10k

just my thoughs

v

[4000GT]

Still trying to understand how same PSI will equal to different amount of oxygen particles providing intercooling is used.

Density of particles...

[4000GT]

Yup, no question he could have made that power with much smaller and cheaper turbos! I think we are all pretty much in agreement on that, I am guessing he didnt want to open the motor and thought the W series would handle whatever the unopened turbo motor would make. Hell he may have found the turbos cheap or had them off other builds and just thought these are cool turbos and chucked them on. it would be great for him to chime in.

[vvega]

Yea, could definatly make more power, but with the engine in question, I don't know if it would be able to make much more power without causing some serious damage.

I think what Akane and vvega are getting at is that the GT35R's are a bit overkill for the engine in its current build. If it were built tougher, then they'd be great

I agree, more will need to be done to the motor (if stock), to take advantage of the big turbo's. Again it really depends what the builder had in mind for the motor. Example, I am tending towards a T51R on my 1UZ, but I wont do the rods / pistons etc straight away, I want to see how far the stock motor can be pushed. if I dyno and get say 450WHP at 10psi it would be foolish for someone to say you should change turbo as it is too big to make that 450WHP you are making...

depends on what you wanted to acheve
psi is not important its teh powercurve
if you could get more power over teh total rev range and still keep the same max power figgure buy useing a smaller turbo then why wouldnt you

you say you want to be educated but i dont see you listing
even garret the makers of teh turbos on that guys car disagree with you and you still mantain your know more than them ??

i dunno but id assume garret would know somethign ...unless im missing somethign

[vvega]

sorry just saw your agreeing with teh smaller turbo thing now...

[Malcolm]

this is ridiculous. I'm going to do this in short sentences to try and make it easy to understand.

Boost pressure is a function of airflow generated by the turbo vs. air consumed by the engine.

Since engine air consumption doesn't change with a different sized turbo, we can consider that to be constant. If we have the same boost pressure that means we are flowing the same volume of air out of the turbo (cfm).

The only thing left that could make the bigger turbo more powerful is more air mass for the same volume (eg higher density), which since pressure is staying the same, as we've already stipulated, means that it has to be cooler (lower temperature).

Provided your smaller turbo is operating within it's efficiency range (learn to read a compressor map), then it shouldn't be producing much more heat than the big one.

To conclude, stop making up shit and pretending you know what you're talking about.

The only way the big turbos might make the car feel more powerful is that they're so laggy that because the power increases rapidly it feels more powerful than it really is.

[BlakJak]

Geezus vvega. Put some effort into spelling and grammar, will you... your posts may make some sense but theyre damned hard work to read...

[mr_monkey]

Geezus vvega. Put some effort into spelling and grammar, will you... your posts may make some sense but theyre damned hard work to read...

Wayne cant help it unfortunately- i can read his stuff fine.

-Nathan

[vvega]

Since engine air consumption doesn't change with a different sized turbo, we can consider that to be constant. If we have the same boost pressure that means we are flowing the same volume of air out of the turbo (cfm).

turbo and compressor housinf effect V.E so yest diffent turnos affect the dynamic Cfm teh engine is inhaling

thats why some people make 200kw @19 psi with a tdo5
and then they make 200kw @ 12 psi on a to4e

the rest of teh rev range may be crap but peak power figures are identical (as you noted)

v

[Malcolm]

how can the VE of the engine possibly change dependant on the turbo? That doesn't even make sense. Provided the air entering the inlet ports is the same temperature, at the same pressure, and isn't considerably more turbulent from one turbo to the other (which is unlikely by the time it's gone through a heap of piping, and intercooler etc), then why should the engine care what kind of turbo the air has come from? The only reason I see for making the same power off less boost from a different turbo is if the smaller one was heating the air too much, and so to get the same mass flow rate you need a considerably higher volumetric flow rate, hence you end up with more pressure for the same air mass (and hence potential to produce power) - at which point you're clearly operating your smaller turbo out of its efficiency range

[vvega]

restiction of the ex housing and of teh compression

obvioulsy a smaller hole restrics flow more considerable
this effects teh v.e of the engine because the egine cant gasp enough air so isnt getting a full charge

its no different to the way that cams affect teh engines v.e

you can work out a engines theritical v.e btu teh you have to add in corrections

v

[4000GT]

how can the VE of the engine possibly change dependant on the turbo? That doesn't even make sense. Provided the air entering the inlet ports is the same temperature, at the same pressure, and isn't considerably more turbulent from one turbo to the other (which is unlikely by the time it's gone through a heap of piping, and intercooler etc), then why should the engine care what kind of turbo the air has come from? The only reason I see for making the same power off less boost from a different turbo is if the smaller one was heating the air too much, and so to get the same mass flow rate you need a considerably higher volumetric flow rate, hence you end up with more pressure for the same air mass (and hence potential to produce power) - at which point you're clearly operating your smaller turbo out of its efficiency range

Wont it change because the temperature IS different between different sized turbo's... as much as you discount it in your discussion, thats why bigger turbos exist, because it does make a difference. The point I made in my very first post was about charge density...

[vvega]

how can the VE of the engine possibly change dependant on the turbo? That doesn't even make sense. Provided the air entering the inlet ports is the same temperature, at the same pressure, and isn't considerably more turbulent from one turbo to the other (which is unlikely by the time it's gone through a heap of piping, and intercooler etc), then why should the engine care what kind of turbo the air has come from? The only reason I see for making the same power off less boost from a different turbo is if the smaller one was heating the air too much, and so to get the same mass flow rate you need a considerably higher volumetric flow rate, hence you end up with more pressure for the same air mass (and hence potential to produce power) - at which point you're clearly operating your smaller turbo out of its efficiency range

Wont it change because the temperature IS different between different sized turbo's... as much as you discount it in your discussion, thats why bigger turbos exist, because it does make a difference.

bigger turbos excist because there are bigger engines
you dont wanna se what goes on teh side of some plane engines....compressors teh size of your head

turbo's are ,made to a specific cfm thast what you buy them too

[Malcolm]

restiction of the ex housing and of teh compression

obvioulsy a smaller hole restrics flow more considerable
this effects teh v.e of the engine because the egine cant gasp enough air so isnt getting a full charge

its no different to the way that cams affect teh engines v.e

you can work out a engines theritical v.e btu teh you have to add in corrections

v

I can see how the turbine housing can effect the VE, although to what extent is hard to gather, my point is more about using a correctly sized turbo VS and oversized one, IMO a properly sized turbo shouldn't be overly restrictive on the exhaust side compared to a oversized one (kinda like how a properly sized exhaust system restricts no less than an oversized one)

[Malcolm]

Wont it change because the temperature IS different between different sized turbo's... as much as you discount it in your discussion, thats why bigger turbos exist, because it does make a difference. The point I made in my very first post was about charge density...

the temperature difference will only be significant if you're operating the smaller turbo outside of its efficiency. If it's properly specced then the smaller one wont be heating much more than the larger one.

[Akane]

Finally Malcolm comes along and cleared it up.

[flygt4]

who actually cares?

wouldnt be hard to sell off the gt35's and get a pair of gt28's or something for it, would probly make money on it

[vvega]

well yes and no
you dont atually pay that much more for bigger turbo's
its more just getting eth right one off that bat that will suit your application :d

v

[vvega]

restiction of the ex housing and of teh compression

obvioulsy a smaller hole restrics flow more considerable
this effects teh v.e of the engine because the egine cant gasp enough air so isnt getting a full charge

its no different to the way that cams affect teh engines v.e

you can work out a engines theritical v.e btu teh you have to add in corrections

v

I can see how the turbine housing can effect the VE, although to what extent is hard to gather, my point is more about using a correctly sized turbo VS and oversized one, IMO a properly sized turbo shouldn't be overly restrictive on the exhaust side compared to a oversized one (kinda like how a properly sized exhaust system restricts no less than an oversized one)

more often in not in factory cars the ex housing is quite restrictive
400 hp ct26 anyone ??
put a larger ex housing on them and they love you long time :d

[4000GT]

Wont it change because the temperature IS different between different sized turbo's... as much as you discount it in your discussion, thats why bigger turbos exist, because it does make a difference. The point I made in my very first post was about charge density...

the temperature difference will only be significant if you're operating the smaller turbo outside of its efficiency. If it's properly specced then the smaller one wont be heating much more than the larger one.

of course when you use terms like properly specced then you cant be wrong. You have a greater probability of being outside the high efficiency islands on a smaller turbo.