boost is boost? turbos compare

[cjridert1]

Looking into getting a 50 trim, but probably will only be pushing ~20psi. I have a 16g now that pushes this - is there any advantage to running a 50/20g outside of not overrunning its efficiency and heating up the intake air? lbs/min would still be the same for 20psi or not?

Thanks guys

 

[VTRICCO]

boost is definately not boost. Bigger turbos might produce the same boost pressure as smaller ones but will flow signifigantly more air at that same psi

 

[silver bullit]

20 psi on a 50 trim is nothing to a t-25/14b.

If you dont have the mods for the additional air flow, there is no point to bump the boost on a bigger turbo if you dont have the mods for it.

 

[Mr Peepers]

Boost is not boost

A 50 trim will be moving more air(lb/min) than a 16g at the same psi. This is because the efficiency will be higher for the 50 trim at that psi, meaning more energy goes towards actually compressing the air rather than just heating it up. This will allow more (dense) air to be stuffed into the cylinders and a leaner afr and/or more advanced timing before knock occurs.

Also, the turbine and turbine housing will be much less restrictive, particularly at higher rpms, giving you better overall flow(or VE). This is something usually overlooked by most.
A turbo is more than just the compressor.

EDIT: I'm a little slow...

 

[VTRICCO]

isnt that what i just finished saying

 

[bacalhau16]

Im not even sure if that is truly what he is asking because that answer should just be obvious. If your asking how different a 16g is compared to a 50trim turbo or compared to a 20g then, that might be a little better. But still it is that different.

OP, would you care to clarify your question a little better?

 

[JayRolla]

If you are thinking of upgrading dont even bother with a 50trim. In my experience's a evo16g is pretty comparable to a 50 trim. The small amount of air gained up top in the rpm band is not worth the loss in spool. This is just my .02

 

[silver bullit]

Boost is not boost

A 50 trim will be moving more air(lb/min) than a 16g at the same psi. This is because the efficiency will be higher for the 50 trim at that psi, meaning more energy goes towards actually compressing the air rather than just heating it up. This will allow more (dense) air to be stuffed into the cylinders and a leaner afr and/or more advanced timing before knock occurs.

Also, the turbine and turbine housing will be much less restrictive, particularly at higher rpms, giving you better overall flow(or VE). This is something usually overlooked by most.
A turbo is more than just the compressor.

EDIT: I'm a little slow...

isnt that what i just finished saying

You 2, i said the same thing but oh well tell em how it is.

 

[Mr Peepers]

You 2, i said the same thing but oh well tell em how it is.

Sure did, that's what the "I'm a little slow" part was for. We're on the same page, but some of us took longer to flip to the next.

 

[cjridert1]

I may not be getting this yet - besides the heated air, is there a difference or not? Ideal gas quick: PV=T since Pressure is the same, volume is lower given higher temps

10torr/10C = 1L 10torr/30C = .33L (units & #s to make math easy with correct result)

Are there other changes/variables present I am missing? If this is it, a 16g is the same as a 50trim if you achieve the same intake temp? i.e. 16g ran ragged with the same intake temp as a 50 trim (ehhh, I know) yields the same potential power increase?

 

[JayRolla]

Lets say a 16g will only flow 36lb/min at its best. A t67 can flow close to 70lb/min. Now with both turbos at 30psi, the 16g still will only flow 36lb/min and the t67 will flow 70lb/min at the same boost level. So no same boost is not the same. The heated air is another factor you have to deal with when running small turbos like a 16g. Thats why a 50trim performs better on pump gas, but both turbos on race fuel or e85 and there is not much of a difference.

 

[turbodsm_125]

there is a diffence in the amount of air flowed. a 50 trim has a bigger impeller and thus will flow more air cooler and creat a more dense charge as stated above numerous times. the bottom line is that it moves more air at the same psi due to the increase in compressor housing size.

 

[cjridert1]

Lets say a 16g will only flow 36lb/min at its best. A t67 can flow close to 70lb/min. Now with both turbos at 30psi, the 16g still will only flow 36lb/min and the t67 will flow 70lb/min at the same boost level. So no same boost is not the same. The heated air is another factor you have to deal with when running small turbos like a 16g. Thats why a 50trim performs better on pump gas, but both turbos on race fuel or e85 and there is not much of a difference.

36lb/min is still a volume rate though right? If the air is compressed the same amount (20psi) and the temp is static, then the volume rate must be the same? If I flow 40lb/min or 30lb/min, this is going to change the pressure inside the system isn't it? Like in a fuel line (granted fluids aren't very compressible) - if you increase the volume flow rate, you need to either increase pressure or increase the line diameter (or decrease temp to lowest density - like 4c for water). Thanks for helping me trying to get this, I don't mean to harass you if it comes off this way - I just only understand the efficiency overrun which leads to higher temps.

 

[bastarddsm]

if nothing else on the engine changes besides the turbo....boost is boost.

 

[colonel_odem]

so, if I go from stock sidemount with 14b and stock cams/intake then:
I put on a race FMIC, 2.5" pipeing, and 264 cams, with a ported and polished head, exhaust mani. and eIII16g turbo, then the boost is not boost? is that what is being said?

 

[daren_p]

if nothing else on the engine changes besides the turbo....boost is boost.

What exactly are you trying to say here? Are you implying that if I run a 16g at say 20 psi & then swap only the turbo for say a FP3065 & also run 20psi I will see the same resaults (ie same amount of airflow & same power)? If so I would have to completely disagree with this.

 

[csgsx23]

What exactly are you trying to say here? Are you implying that if I run a 16g at say 20 psi & then swap only the turbo for say a FP3065 & also run 20psi I will see the same resaults (ie same amount of airflow & same power)? If so I would have to completely disagree with this.

I think everyone agrees with this.

 

[bastarddsm]

DAREN,

yes. A turbo can only move as much air as the engine will let it. Granted a 3065 will be more efficient and will not heat the air as much, so the lbs/min will rise...some, but the CFM will stay very much unchanged. Where you see the big gains is having a 16 maxxed out that wont hold 20psi to redline, then switching to a 3065, and running 20psi, where it won't even break a sweat.

FYI the numbers i used were theoretical.

 

[northendtrooper]

You need to look for a CFM chart that compares Turbos together. That would answer your question

You must be logged in to view this image or video.

 

[bastarddsm]

No. i don't need to look at a chart to see somthing I allready know.

 

[JayRolla]

No. i don't need to look at a chart to see somthing I allready know.

So your saying if I have a 16g running 28psi all the way to redline that it will make the same power as a t67 at 28psi all the way to redline?? Lets say the motors where using race gas the that intake temps are almost the same.

 

[cjridert1]

So your saying if I have a 16g running 28psi all the way to redline that it will make the same power as a t67 at 28psi all the way to redline?? Lets say the motors where using race gas the that intake temps are almost the same.

This is what I was thinking, sure a big turbo makes more power at 20psi is what intuition tells me - could heat be the only reason? 28psi is probably unreasonable for a 16g (I think, Im sure there is some exception), maybe stick with 20? Besides heat/inefficiency (which can be battled a bit) it seems it should be the same. Race gas shouldnt matter here (theoretical, so we'll keep variables low) if intake temps are the same then pre-det. potential is same I would think?

 

[oldman420]

hahaha, this thread is becoming ignorant. We are not even answering the original question, just flaming. A 20g will not be alot better that a 16g on your appication. You would get a denser charge and your turbo would run with greater effeciancy, but the horse power gain would not be worth the money. Look at something with a larger turbine, rather that just a larger compressor housing. My .02 cents/.

 

[knochgoon24]

Psi is a pressure. At a certain RPM, your car will be able to use X amount cubic feet of air. As you increase the pressure, you fit more air into the same space.

It all comes down to efficency. A bigger turbo will move X amout of air more efficently. Since it can move more air, it's able to keep the 28psi all the way to the redline. The smaller turbo, which can't move as much air, would see a pressure drop.

 

[Black_Bullet]

Lets say a 16g will only flow 36lb/min at its best. A t67 can flow close to 70lb/min. Now with both turbos at 30psi, the 16g still will only flow 36lb/min and the t67 will flow 70lb/min at the same boost level. So no same boost is not the same. The heated air is another factor you have to deal with when running small turbos like a 16g. Thats why a 50trim performs better on pump gas, but both turbos on race fuel or e85 and there is not much of a difference.

I think theres a big enough difference to go 50trim if were talking about pump gas cars.
The 50 trim would allow a more aggressive tune due to its efficiency is better.
On maxed out race gas/ e85 tunes then id agree that they are near the same.
16gs have been proven to flow upwards of 40 lbs a min.

Psi is a pressure. At a certain RPM, your car will be able to use X amount cubic feet of air. As you increase the pressure, you fit more air into the same space.

It all comes down to efficency. A bigger turbo will move X amout of air more efficently. Since it can move more air, it's able to keep the 28psi all the way to the redline. The smaller turbo, which can't move as much air, would see a pressure drop.

Exactly. ^^^

Say you can get turbo ABC to make 20 psi, but it falls to 15 by 7k.
Then you go slap on XYZ turbo and it makes 20 psi all the way to 8k,
then obviously the XYZ turbo holding that boost longer will provide more power.
Thats were the more air flow of a bigger turbo really comes into play.

The reason turbos have a pressure drop is because they have reached the top of their compressor maps. An increase of rpms or stroke ( means an increase of air digested.)
which in turn increases the amount of air the turbo now must supply for it to hold the set boost ...

Now boost falling as rpms rise doesnt always mean the turbo is flowing less than it was when the boost gauge registered its peak psi; it just means your just stuck at the turbos peak air flow since the compressor cant physically "squeeze" anymore air into the engine...