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Larger turbo vs stock turbo at higher boost?

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#1
A lot of people upgrade their turbo to a larger one.

What would happen if you just changed the intercooler, and were able to just run the stock Turbo at higher PSI, and run a mild tune on it (like +5PSI additional overboost)?
 


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#2
I wish I could afford a bigger turbo... Need so many other parts to go with it so not worth it IMO. I am just going to get the Access port then an intake plus a few other small power mods and leave it at that..

not sure if the stock turbo can handle any more boost psi as that's why the overboost feature only lasts for 30 seconds... To stop it from overheating ect like if it's in a country with 45 plus degree summers ect.. IMO, I could be wrong tho.
A lot of people upgrade their turbo to a larger one.

What would happen if you just changed the intercooler, and were able to just run the stock Turbo at higher PSI, and run a mild tune on it (like +5PSI additional overboost)?
Sent from my Mi MIX 2S using Tapatalk
 


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Austin
#3
A scenario for explanation: Two turbos, one big one small. Both at 18 psi. The bigger turbo will produce that at a higher efficiency and lower turbine speed, meaning waaay less heat generated. The difference in turbine rpm could be upwards of 20k rpm. Thats a big difference. So... not only will the bigger turbo make more power at the same boost level (because cold air is more dense, less heat than small turbo), it will do so more safely (less heat, less rpm strain on turbo)
 


slopoke

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#4
Let's not try to reinvent the wheel here. I do believe a stock turbo with E30 tuning is topped out at 230whp. So if you want to go more in terms of HP, a hybrid or bigger turbo is the next step. If you are not familiar with the differences between a Big turbo and a hybrid are. Hybrids spin up fast like a stock turbo, and makes quite a bit more HP on top. Big turbos are slower to spool up , but the HP just keeps building, way past what a hybrid can do.

So, you have to figure out what your goals are, if 230ish whp is fine, then upgrade the FMIC, maybe the intake and exhaust, find a tuner and get a E30 tune. More HP with gobs of bottom end torque, then a hybrid. If you want massive top end, go bigger turbo. Sky's the limit, but you gotta pay to play.

I have a hybrid, it's putting out lower 280 whp with an E30 tune. I've hit the limits of the stock fuel system. I can get a bit more by going aux fuel, how much more I can safely get, without big sacrifices in longevity, we will find out once my aux fuel setup is installed.
 


M-Sport fan

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#5
I wish I could afford a bigger turbo... Need so many other parts to go with it so not worth it IMO. I am just going to get the Access port then an intake plus a few other small power mods and leave it at that..
The Aussie cars are running the USDM/Western Hemisphere based factory tune, and not the Brit/Euro/R.O.W. based tune, enabling you to use an AP? [dunno]
 


OP
M
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Thread Starter #6
I wonder if you'll notice the increase from 190HP stock, to 230HP..

I was hoping for more like ~250HP, and a quick spool-up, without going through the cost of another turbo.
For that, I'll probably need to run the system at 28PSI.


Would you think that a larger turbo can generate more HP at lower PSI, or do the same PSI give the same HP on the output?
 


slopoke

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#7
I wonder if you'll notice the increase from 190HP stock, to 230HP..

I was hoping for more like ~250HP, and a quick spool-up, without going through the cost of another turbo.
For that, I'll probably need to run the system at 28PSI.


Would you think that a larger turbo can generate more HP at lower PSI, or do the same PSI give the same HP on the output?
I'm hitting high 25's continuous with my hybrid Revo S242 turbo. I do believe 27ish is tops for it. Air volume is another factor. For more air volume at lower psi, a larger compressor is needed.
 


Ford ST

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#8
I wonder if you'll notice the increase from 190HP stock, to 230HP..

I was hoping for more like ~250HP, and a quick spool-up, without going through the cost of another turbo.
For that, I'll probably need to run the system at 28PSI.


Would you think that a larger turbo can generate more HP at lower PSI, or do the same PSI give the same HP on the output?
The stock turbo cannot support that much power it's simply too small. In the upper RPM range it falls on its ass. I suggest you do some research on how boost works, especially how it changes in the RPM range and throttle body open percentage. Not being rude the stock turbo can only do so much in terms of horsepower. You can increase torque significantly on the stock unit.

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Last edited:

danbfree

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#9
I wonder if you'll notice the increase from 190HP stock, to 230HP..

I was hoping for more like ~250HP, and a quick spool-up, without going through the cost of another turbo.
For that, I'll probably need to run the system at 28PSI.


Would you think that a larger turbo can generate more HP at lower PSI, or do the same PSI give the same HP on the output?
Definitely more power with a big turbo at the same PSI as a stock turbo, there is a lot more volume at the same pressure and like what was said before, at lower temps as it works less hard to produce that power... However, keep in mind that ethanol does have a cooling effect so running e30 not only provides higher octane for the fuel itself, it can be tuned more aggressively running cooler too. Over just a 93 tune, it feels like I'm making 20 HP/ 30 TQ more on the e30 I'm running and boy you can feel it. My dizzy tune runs ~24.75 max psi on 93 but is tuned to jump up to 26.5 psi on e30 as it runs cooler. Still with the stock turbo still only having a 1 7/8" outlet diameter, the stock intake and exhaust is still not very restrictive, although intake and exhaust over stock on e30 would get you that extra 10 HP / 15 TQ if you can afford the extra grand to be under Cobb's version of "Stage 3".

Although I'm personally happy with e30 on stock turbo, you might want to look at a hybrid, some nice choices coming out these days!
 


OP
M
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Thread Starter #10
Thanks for the replies.

It was like I suspected.
I'll think it over, but think to just upgrade the intercooler for now.
Will come back here, once I did the plunge!
 


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#11
The Aussie cars are running the USDM/Western Hemisphere based factory tune, and not the Brit/Euro/R.O.W. based tune, enabling you to use an AP? [dunno]
I hope I can use an AP lol.. Is there something that says it won't work on the Australian version??

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danbfree

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#12
The stock turbo cannot support that much power it's simply too small. In the upper RPM range it falls on its ass. I suggest you do some research on how boost works, especially how it changes in the RPM range and throttle body open percentage. Not being rude the stock turbo can only do so much in terms of horsepower. You can increase torque significantly on the stock unit.
What's interesting is that the stock turbo wastegate spring is only 5.6 psi and Jason of Dizzy is experimenting with a 7 psi upgraded spring and a tune to support it... part of what makes his tune smoother is that he dials back max boost just a touch and even on the stock setup this does help hold boost a little better as revs climb. But ultimately that weak spring does release boost a little early, so that's a big factor in the boost dropping off at upper RPM's with the stock turbo. If he is successful, he's hoping to release a combo of upgraded WG spring and supporting tunes for it, should be interesting!
 


Quisp

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#13
What's interesting is that the stock turbo wastegate spring is only 5.6 psi and Jason of Dizzy is experimenting with a 7 psi upgraded spring and a tune to support it... part of what makes his tune smoother is that he dials back max boost just a touch and even on the stock setup this does help hold boost a little better as revs climb. But ultimately that weak spring does release boost a little early, so that's a big factor in the boost dropping off at upper RPM's with the stock turbo. If he is successful, he's hoping to release a combo of upgraded WG spring and supporting tunes for it, should be interesting!
I had stock turbo turbosmart wastegate upgrade with a Tune + tune 2 years ago.
 


A7xogg

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Hampton roads
#14
What's interesting is that the stock turbo wastegate spring is only 5.6 psi and Jason of Dizzy is experimenting with a 7 psi upgraded spring and a tune to support it... part of what makes his tune smoother is that he dials back max boost just a touch and even on the stock setup this does help hold boost a little better as revs climb. But ultimately that weak spring does release boost a little early, so that's a big factor in the boost dropping off at upper RPM's with the stock turbo. If he is successful, he's hoping to release a combo of upgraded WG spring and supporting tunes for it, should be interesting!
It does help with holding boost, but it still drops off, not nearly as much or as fast but still want an upgraded turbo
 


Jerickson88

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#15
Boost pressure is irrelevant. It’s torque targeting. We don’t just crank up the boost for more power. Temperature and air density have effect on how much boost is made, not turning open a valve to make it so.
 


Jerickson88

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#18
So, if I bolted a TS wastegate in with a 7lb springs, will I notice a difference, bone stock? I can tell you that getting away from an electronic bypass valve, definitely makes a difference in performance.
 


danbfree

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#19
Boost pressure is irrelevant. It’s torque targeting. We don’t just crank up the boost for more power. Temperature and air density have effect on how much boost is made, not turning open a valve to make it so.
Absolutely, and it's easy to see this in action, on cool days you often see less boost because he's making all the power it should and doesn't need to max out boost and on warmer days, it needs to max out boost to try to make it's targeted power, but we also need to have a starting point for discussion, so I can see why people discuss max boost.

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Broward county Fl
#20
I wonder if you'll notice the increase from 190HP stock, to 230HP..

I was hoping for more like ~250HP, and a quick spool-up, without going through the cost of another turbo.
For that, I'll probably need to run the system at 28PSI.
When stock horsepower is mentioned people are referring to HP at the flywheel.
When tuned horsepower is talked about they are talking about at the Wheels.
Stock horsepower at the wheels is about 15% less than what you see advertised.
Stock horsepower at the wheels is closer to 170 HP +/- 5 hp.
so put simply you will notice the difference between stock and tuned.
Not sure anyone has achieved 250 WHP with a stock turbo.
I am running 28 psi on 93 oct and I am not close to 250 whp and I don't think e30 would get me close either.
 




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