How much Boost can i run?

Q&A regarding engines, turbos, and intercoolers and power upgrades

How much Boost can i run?

Postby Selsvik » Fri Nov 22, 2019 8:35 pm

hi!
I am wondering how muvh boost i can run on stock engine. or stock ish
I have recently upgraded the turbo with a bigger turbo from GT4-PLAY, the S148 Hybrid Turbo.
https://gt4-play.co.uk/shop/turbo-technics-s148-560
And i also have the 3" DeCat Downpipe from the same company, and i have mounted a cheap ebay muffler for less resistance.

Stock with no upgrades i was told that i can run 1Bar of boost safely. but now that i have these upgrades the exhaust have much less resistance and is then safer to run high boost(someone told me).
so how much boost can i run safely with these upgrades? :)

Mods:
S148 Turbo
3" DeCat Downpipe from gt4-play
Low resistance 3" ebay muffler
Pod filter
Silicone intake pipe
Members don't see the above ad. Register now - it's free!
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 42
Joined: Sun Oct 28, 2018 8:02 pm

Re: How much Boost can i run?

Postby underscore » Fri Nov 22, 2019 8:39 pm

The general consensus seems to be 1 bar or 14.7 psi is pushing the limit for the stock headgasket. I'd aim for 12-13 tops to be safe.
★ 1991 GTFour RC ~ "Rebel Scum" ★
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 4322
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: How much Boost can i run?

Postby Magroo » Fri Nov 22, 2019 8:59 pm

I can confirm I blew my head gasket by boosting over 15 lbs. This was the stock jdm composite gasket. Upgraded to arp studs and cometic MLS gasket now.
Magroo
Club Member
 
Posts: 170
Joined: Fri Jun 06, 2014 8:07 pm

Re: How much Boost can i run?

Postby Selsvik » Fri Nov 22, 2019 9:05 pm

so the headgasket is the weak point on this engine?
If sometime in the future the headgasket blows, what parts is recommended to change? and yes, a stroonger headgasket :)
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 42
Joined: Sun Oct 28, 2018 8:02 pm

Re: How much Boost can i run?

Postby silverarrow » Fri Nov 22, 2019 9:46 pm

1 bar of boost on stock turbo is NOT the same as 1 bar of boost on any bigger turbo. Your safest bet is to install a wideband o2 on your downpipe and keep an eye on your afr while you slowly increase the boost. I ran 1 bar of boost on one of my previous ST185s just fine on stock turbo though. I ran 12 psi(minimum ext. wastegate spring) on a 60 trim T3/T04e .63 ar turbo kit for a little while, but my engine would ping.

Boost typically doesn't kill motors, it's the tune. With that upgraded turbo, you're probably going to max out your injectors and go kaboom from running too lean and with the stock tmic you're going to run into heat soak which may or can lead to power loss and maybe even engine failure.

Whoever that told you that you can run more boost because you have said upgrades isn't really bright. Not to offend, but find a friend that actually knows what he/she is talking about.
89 240sx
02 Nissan Frontier 4x4 Supercharged
silverarrow
Club Member
 
Posts: 655
Joined: Mon Aug 09, 2004 5:07 am
Location: Inland Empire, Southern California

Re: How much Boost can i run?

Postby freddie » Sat Nov 23, 2019 2:31 am

Bar is a metric measurement for Atmospheric Pressure. 1Bar = 1 Atmosphere.
Atmospheric Pressure (measurement) depends on where you are located and how high above sea level
your location is.
Where I am located (Australia) is not so high above sea level, therefore 1bar = 9.8psi. That is what we
work on.
So I think running a boost pressure of say 10psi is pretty ordinary. The A/M ECU and Turbo I am using
in my 205 engine is set at 1.85bar. max. The standard engine in my 165 (with a few mods to help it
breath a bit better) ran at 1.2bar (12psi) exceeding three years of DD without any problem.
freddie
Club Member
 
Posts: 98
Joined: Mon Jan 23, 2012 9:20 am

Re: How much Boost can i run?

Postby 93celicaconv » Sun Nov 24, 2019 3:10 pm

freddie wrote:Bar is a metric measurement for Atmospheric Pressure. 1Bar = 1 Atmosphere.
Atmospheric Pressure (measurement) depends on where you are located and how high above sea level
your location is.
Where I am located (Australia) is not so high above sea level, therefore 1bar = 9.8psi. That is what we
work on.
So I think running a boost pressure of say 10psi is pretty ordinary. The A/M ECU and Turbo I am using
in my 205 engine is set at 1.85bar. max. The standard engine in my 165 (with a few mods to help it
breath a bit better) ran at 1.2bar (12psi) exceeding three years of DD without any problem.

Not quite right.

Bar is a metric unit of pressure. Atmosphere is the average pressure at sea level (average in that there are high pressure and low pressure deviations all the time). While BAR and ATMOSPHERE are not at all related, 1 Atmosphere = 1.013 BAR. 1 Atmosphere also equals 14.7 psi.

Atmospheric pressure at 9.8 psi would be at an elevation of 10,750 feet above sea level. That is not very close to sea level at all. Australia's highest peak, Mount Kosciuszko, is 2228 meters (or 7,310 feet) above sea level. So I don't know where in Australia you would ever encounter an atmospheric pressure as low as 9.8 psi.

But, 1 BAR = 14.50377 psi, no matter what, no matter where (these terms are not atmospheric pressure related, just different units of measurement for pressure).
93celicaconv
Club Member
 
Posts: 433
Images: 26
Joined: Sun Jul 12, 2015 11:08 am

Re: How much Boost can i run?

Postby grip-addict » Sun Nov 24, 2019 11:24 pm

Silver arrow is absolutely correct. The max boost you can run on any aftermarket turbo is Wastegate until you get it on a dyno to check afr's. Installing a wideband is also an option. Just for comparisons sake, the gt3071r makes about 300 whp at 13 psi on the 3rd gen 3s.
grip-addict
Newbie
 
Posts: 8
Joined: Sat Oct 05, 2019 1:31 pm

Re: How much Boost can i run?

Postby freddie » Mon Nov 25, 2019 3:55 am

Not quite right.

Bar is a metric unit of pressure. Atmosphere is the average pressure at sea level (average in that there are high pressure and low pressure deviations all the time). While BAR and ATMOSPHERE are not at all related, 1 Atmosphere = 1.013 BAR. 1 Atmosphere also equals 14.7 psi.

Atmospheric pressure at 9.8 psi would be at an elevation of 10,750 feet above sea level. That is not very close to sea level at all. Australia's highest peak, Mount Kosciuszko, is 2228 meters (or 7,310 feet) above sea level. So I don't know where in Australia you would ever encounter an atmospheric pressure as low as 9.8 psi.

But, 1 BAR = 14.50377 psi, no matter what, no matter where (these terms are not atmospheric pressure related, just different units of measurement for pressure).

Sorry I stuffed up.
Standard Atmospheric Pressure at Sea Level is 14.7psi = 101.325kpa =1bar (The hard measurement is 14.695psi)
In my neck of the woods the Atm. is 14.77psi = 1018mb (that is at 12.00am 25/11 2019)

My previous explanation is wrong. Total pressure is the Atm + the pressure required. But unit of measurement only relates to the pressure
applied eg a tyre pressure of say 32psi (220kpa) is measured as 32psi (and not + 1Atm)

Therefore 1bar =(approx.) 14.7psi. 10psi = 689.2mb or 0.68bar. 12psi = 0.827bar 18psi = 1.24bar.

So 1bar 14.7psi on a stock engine (with a good few miles on it) may be a bit high.

As I am a qualified plumber and Hydraulic Draftsman, I look at Turbo's like pumps, while pressure and volume are similar,
they are not the same, so I like to think that the bigger the pump, the more mass or volume you are going to get and
pressure is what is going move the mass. No matter what the size of the Turbo is, if you are running say 15psi, then the max.
pressure to the engine cylinder is going to be 15psi. However the CFM volume can increase with the size of the Turbo.

Of cause there are other factors to be taken into consideration such as air can be compressed (water and some fluids
cannot be compressed.) Size of the plenum chamber/inlet manifold and gas flow etc. and engine dynamics.
freddie
Club Member
 
Posts: 98
Joined: Mon Jan 23, 2012 9:20 am

Re: How much Boost can i run?

Postby 93celicaconv » Mon Nov 25, 2019 11:36 am

Thanks for your clarification and your more detailed response/explanation. Excellent response with experience backing it up!
93celicaconv
Club Member
 
Posts: 433
Images: 26
Joined: Sun Jul 12, 2015 11:08 am

Re: How much Boost can i run?

Postby MWP » Mon Nov 25, 2019 5:37 pm

Everyone giving advice.... but no one has asked which gen of the 3SGTE he has?
It makes quite a bit of a difference to the correct reply.
My collection of GT4 documentation: http://gt4.mwp.id.au
[color=Blue]Daily:
Toyota RAV4 ACA23R
Race-Car: Toyota GT4 ST185 5S-GTE
MWP
Established Member
 
Posts: 1614
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: How much Boost can i run?

Postby Selsvik » Thu Nov 28, 2019 6:36 pm

i have the ST185, therefore 2.gen. 3SGTE :)
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 42
Joined: Sun Oct 28, 2018 8:02 pm

Re: How much Boost can i run?

Postby Gert » Thu Nov 28, 2019 7:07 pm

Selsvik wrote:so how much boost can i run safely with these upgrades? :)

Mods:
S148 Turbo
3" DeCat Downpipe from gt4-play
Low resistance 3" ebay muffler
Pod filter
Silicone intake pipe

There is no easy answer for this, IMHO.
Meaning, what is your goal? Are you going to boost the car in fifth gear for 10 minutes? Or are you only going to push 1 bar in first and second gear. In second, she can reach 100 km/h, theoreticaly enough in most countrys :D

And, what fuel? What is the condition of the engine? At what outside temps are you driving. How healthy is the cooling system? Etc, etc.
Gert
Club Member
 
Posts: 53
Joined: Tue Sep 29, 2015 8:53 am

Re: How much Boost can i run?

Postby Selsvik » Tue Dec 10, 2019 6:37 pm

sorry for late answer. But in theory the engine should be in good condition, since i am the 3. owner and the preowners have changed oil every 5000km and filter every 10 000km. but still after changing broken turbo, it still uses a bit oil...
the cooling system is fine! The coolant has also been changed when i changed turbo, so thats good.

it has only run 140 000km, so should be in good shape. but because of this oil usage, i am a bit unsure...

was aiming for 1. 2. and 3. gear,

outside temp now inwinter is cold

Fuel - 98octane, highest quality fuel
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 42
Joined: Sun Oct 28, 2018 8:02 pm


Return to Performance and Power

Who is online

Users browsing this forum: No registered users and 3 guests