max power from stock turbo
07-29-2003 | 07:23 PM
#1
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max power from stock turbo
I own a 2002 wrx and was wondering what the stock turbo can handle. I have heard that it can be safely turned up to 15 pounds on stock injectors. But what about bigger injectors? If you got bigger injectors, fuel pump and either a re-flash or UTEC; what could the turbo safely handle for power or boost?
07-29-2003 | 07:54 PM
#2
You answered your own question. Most people say the stock turbo will fall out of it's efficency range around 15 psi. They also say the neighborhood of 280hp is all a stock turbo'd WRX can safely produce, irreguardless of injectors, EM, whatever.
07-30-2003 | 03:16 PM
#3
Well what you COULD do,
is do some really really really specific calculations for your car.
Figure out some Pressure ratio: (Boost+1 ATM)/ 1 ATM
and flow rates of your engine:
CFM = [(liters)*(rpm)*(Volumetric efficiency)*(pressure ratio)]
----------------------------------------------------------------------
5660
VE would be around 90 percent-ish (use 90 in the formula, not .90)
Remember to compensate for Altitude,humidity, and temperature when calculating pressure ratio!!!
And then go look @ a compressor flow map
Then plot the path your car would take in each gear under different load.
Then go plot an "ideal line" w/ the most boost possible while still staying in the efficiency range of the turbo.
To make the long story short, go to your really expensive EBC and make gear/rpm specific boost. You *could* make as much psi as the fuel system and flow and the stock internal components can physically endure, so you could program say 1.5 bar @ 5000 rpm, which would be ~400 cfm through the turbo. Now I have NO idea how much the stock TD04 can flow but @ 7300 rpm fuel cut, you'll be @ almost 600 cfm which I know the TD04 can't flow.
Anyways you can max out your stock turbo by making the turbo make MAX possible efficient boost under every rpm and engine load condition.
is do some really really really specific calculations for your car.
Figure out some Pressure ratio: (Boost+1 ATM)/ 1 ATM
and flow rates of your engine:
CFM = [(liters)*(rpm)*(Volumetric efficiency)*(pressure ratio)]
----------------------------------------------------------------------
5660
VE would be around 90 percent-ish (use 90 in the formula, not .90)
Remember to compensate for Altitude,humidity, and temperature when calculating pressure ratio!!!
And then go look @ a compressor flow map
Then plot the path your car would take in each gear under different load.
Then go plot an "ideal line" w/ the most boost possible while still staying in the efficiency range of the turbo.
To make the long story short, go to your really expensive EBC and make gear/rpm specific boost. You *could* make as much psi as the fuel system and flow and the stock internal components can physically endure, so you could program say 1.5 bar @ 5000 rpm, which would be ~400 cfm through the turbo. Now I have NO idea how much the stock TD04 can flow but @ 7300 rpm fuel cut, you'll be @ almost 600 cfm which I know the TD04 can't flow.
Anyways you can max out your stock turbo by making the turbo make MAX possible efficient boost under every rpm and engine load condition.
07-30-2003 | 03:54 PM
#4
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Thanks for the input guys
I guess the next step is finding a compressor map(any ideas) for my turbo.
and If I get the UTEC I will be able to use it like an electrionic boost controller right?
verc- for using that formula, in liters Would I use 2.0 liters or 0.5 liters for each cylinder? And for pressure ratio ex. I would use
[(15+1)*14.7] / 14.7 =16 Is that right???
[2*5000*90*16] =14400000???
then compare it to a map
I guess the next step is finding a compressor map(any ideas) for my turbo.
and If I get the UTEC I will be able to use it like an electrionic boost controller right?
verc- for using that formula, in liters Would I use 2.0 liters or 0.5 liters for each cylinder? And for pressure ratio ex. I would use
[(15+1)*14.7] / 14.7 =16 Is that right???
[2*5000*90*16] =14400000???
then compare it to a map
07-30-2003 | 04:32 PM
#5
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You need your units to match in the top eqn. You have atm for one and psi for the other. Your pressure ratio should be about 2 for the stock turbo. Also you need to make your engine into cubic feet of displacement which is 1L=0.0353ft^3. Change that and you are in business. That will also make your CFM number to a reasonable number
. EDIT: SOrry your vol eff will also need to be in a decimal form(i.e.0.9)
Stephen
. EDIT: SOrry your vol eff will also need to be in a decimal form(i.e.0.9)Stephen
Last edited by XstephenX; 07-30-2003 at 04:35 PM.
07-30-2003 | 09:30 PM
#6
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HUH?!?
That's a lot of work for a TDO4. You guys are more dedicated than me.
15 psi and 270 sounds about right. Of course, you could port the housing and put a 16G wheel in. That would give the capacity to run 350 hp and around 22psi.
Oh yeah, and it'd only cost you $400
That's a lot of work for a TDO4. You guys are more dedicated than me.
15 psi and 270 sounds about right. Of course, you could port the housing and put a 16G wheel in. That would give the capacity to run 350 hp and around 22psi.
Oh yeah, and it'd only cost you $400
07-31-2003 | 10:11 PM
#7
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Originally posted by impreza7
HUH?!?
That's a lot of work for a TDO4. You guys are more dedicated than me.
15 psi and 270 sounds about right. Of course, you could port the housing and put a 16G wheel in. That would give the capacity to run 350 hp and around 22psi.
Oh yeah, and it'd only cost you $400
HUH?!?
That's a lot of work for a TDO4. You guys are more dedicated than me.
15 psi and 270 sounds about right. Of course, you could port the housing and put a 16G wheel in. That would give the capacity to run 350 hp and around 22psi.
Oh yeah, and it'd only cost you $400
You said capacity... so you mean with the right upgrades the stock turbo would be good for up to 350 hp(crank?). how whould that affect spool up? and $400, is that for porting the intake/exhaust housing and the 16Gwheel?
So upgrades I would probably need would be a bigger top mount intercooler(btw what is the stock intercooler good up to?), bigger fuel pump and injectors(how big of fuel pump and injector?), and a reflash or a piggyback to handle it.
ANd could the engine safely handle that without beefing it up?
You need your units to match in the top eqn. You have atm for one and psi for the other. Your pressure ratio should be about 2 for the stock turbo. Also you need to make your engine into cubic feet of displacement which is 1L=0.0353ft^3. Change that and you are in business. That will also make your CFM number to a reasonable number. EDIT: SOrry your vol eff will also need to be in a decimal form(i.e.0.9)
2*5660*0.90*2=20376
I still don't understand this "1L=0.0353ft^3".
What does "^" stand for? and you said I need to "make my engine into cubic feet of displacement ", Is that what I sould use for (liters)?
Thanks XstephenX and impreza7,
This really helps a lot
08-01-2003 | 03:03 AM
#8
Registered User
Joined: Jan 2003
Posts: 185
Originally posted by nitro
a 16G wheel??? what is the stock one? and you are referring to the compressor wheel right?
You said capacity... so you mean with the right upgrades the stock turbo would be good for up to 350 hp(crank?). how whould that affect spool up? and $400, is that for porting the intake/exhaust housing and the 16Gwheel?
So upgrades I would probably need would be a bigger top mount intercooler(btw what is the stock intercooler good up to?), bigger fuel pump and injectors(how big of fuel pump and injector?), and a reflash or a piggyback to handle it.
ANd could the engine safely handle that without beefing it up?
I tryed this....
2*5660*0.90*2=20376
I still don't understand this "1L=0.0353ft^3".
What does "^" stand for? and you said I need to "make my engine into cubic feet of displacement ", Is that what I sould use for (liters)?
Thanks XstephenX and impreza7,
This really helps a lot
a 16G wheel??? what is the stock one? and you are referring to the compressor wheel right?
You said capacity... so you mean with the right upgrades the stock turbo would be good for up to 350 hp(crank?). how whould that affect spool up? and $400, is that for porting the intake/exhaust housing and the 16Gwheel?
So upgrades I would probably need would be a bigger top mount intercooler(btw what is the stock intercooler good up to?), bigger fuel pump and injectors(how big of fuel pump and injector?), and a reflash or a piggyback to handle it.
ANd could the engine safely handle that without beefing it up?
I tryed this....
2*5660*0.90*2=20376
I still don't understand this "1L=0.0353ft^3".
What does "^" stand for? and you said I need to "make my engine into cubic feet of displacement ", Is that what I sould use for (liters)?
Thanks XstephenX and impreza7,
This really helps a lot
the "^" stands for power. in this case..it woul dbe to the third power.
08-01-2003 | 08:05 AM
#9
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sorry that is saying that there are 0.0353 cubic feet in one liter. I calculated it and it comes out to around 635CFM that your turbo needs to flow. I don't have, or know where to get, a stock turbo map but if you got one then you would be able to tell what horsepower the turbo would be good to(in its efficient range). BTW that number is at 5krpm.
Stephen
Stephen
08-01-2003 | 05:04 PM
#11
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Joined: Nov 2002
Posts: 79
From: colorado
details
The TD04-13G is rated at a max flow of 360 CFM at 17 psi, but can hold only about 11 psi, at 7000 rpm on our 2 L engine because the engine wants more flow than it can provide (ie about 460 CFM at 85% VE and a pressure ratio of 2.18 -- 17 psi). It can support almost 24 psi at 3000- 4000 rpm.
http://www.stealth316.com/images/td04-13g-raw.gif
If you put a 16G compressor on the TD04 you'd strangle the engine on exhaust back pressure, it has a 6cm exhaust side, and the stock exhaust side for the 16G is a 7 cm.
360 CFM works out to a crank shaft power out of about 250 hp, if you over spin the turbo you can get up in the neighborhood of 280 but your effeciency is terrible and the air charge will be quite hot -- like over 350 deg F --- can you say "detonation territory" ?
The stock injectors can handle all the air flow out of the stock turbo especially if you run a high density race gas.
Larry
http://www.stealth316.com/images/td04-13g-raw.gif
If you put a 16G compressor on the TD04 you'd strangle the engine on exhaust back pressure, it has a 6cm exhaust side, and the stock exhaust side for the 16G is a 7 cm.
360 CFM works out to a crank shaft power out of about 250 hp, if you over spin the turbo you can get up in the neighborhood of 280 but your effeciency is terrible and the air charge will be quite hot -- like over 350 deg F --- can you say "detonation territory" ?
The stock injectors can handle all the air flow out of the stock turbo especially if you run a high density race gas.
Larry
Last edited by hotrod; 08-01-2003 at 05:15 PM.
08-02-2003 | 09:54 AM
#12
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The TD04-13G is rated at a max flow of 360 CFM at 17 psi, but can hold only about 11 psi, at 7000 rpm on our 2 L engine because the engine wants more flow than it can provide (ie about 460 CFM at 85% VE and a pressure ratio of 2.18 -- 17 psi). It can support almost 24 psi at 3000- 4000 rpm.
How come the engine can support "24 psi at 3000- 4000 rpm"? Does it have to do with the speed of the engine vs the amount of air that can get stuffed through the valves before they close; and between 3000 - 4000rpm the turbo has full boost so that is when it can support the most psi (24) at the slowest engine speed. As the engine gets faster the amount of psi it can take in is less and less untill 11psi at 7000rpm?
So porting the intake and exhaust manifolds whould greatly aid in alowing more power throughout the rpm range; while not increasing air intake charge? whould porting affect the strength of the engine?
So at what rpm would be the best time to shift in each gear?
I almost forgot, thanks for the link to the compressor map
Last edited by nitro; 08-02-2003 at 09:57 AM.
08-02-2003 | 11:13 AM
#13
VIP Member
Joined: Nov 2002
Posts: 79
From: colorado
flow and pressure
A turbocharger is a constant pressure variable flow device. By that I mean you set the output pressure, and it will flow what ever amount of air it takes to hold that pressure (assuming your with in its limits).
The thing that actually determines how much air you flow at a given pressure is the engine displacement, your rpm and the effeciency of the valve heads, intake manifold.
You can put a 1000 CFM rated turbo charger on a 2 liter engine and it will flow essentially the same air flow as a 500 CFM turbo, because the engine is only capable of accepting 460 CFM of flow at 17 psi.
At 3000 - 4000 rpm the engines air flow requirement falls right in the sweet spot of the stock turbos compressor map and the turbo will supply all the air the engine will accept at those rpms and max pressure for the turbo which is about 24 psi boost. (of course you may detonate like crazy at that boost and kill the engine, but the turbo is ready willing and able in that rpm range)
The guys who have run Delta Dash logs have shown that the actual manifold pressure is a lot lower than your boost gauge reads. The gauge just does not read fast enough to show the huge down turn in pressure, because you are only at 7000 rpm for a half a second or so, under max acceleration. Even a VF22 won't hold 17 psi at red line, all though the boost gauge tells you it does.
Yes the weak point in the stock WRX motor is the ability of the valves, heads, cams and intake/exhaust manifold to breath. The engine only flows at 80%+ VE at red line, the RA spec C engine which has much better head design with the AVCS cams flows at about 93% VE at 7000 rpm.
The biggest single problem is the stock cams are relatively mild cams. Once you improve the cams then you need porting and valve work to get higher rpm and breathing at high rpm. The stock intake and exhaust manifolds are fair to good. The stock exhaust works well up into the high 300 hp range, and gives excellent low end torque. Headers are showing their value at high rpm, but typically reduce low end torque enough that many folks go back to stock exhaust manifolds to get back around the town driveability.
Larry
The thing that actually determines how much air you flow at a given pressure is the engine displacement, your rpm and the effeciency of the valve heads, intake manifold.
You can put a 1000 CFM rated turbo charger on a 2 liter engine and it will flow essentially the same air flow as a 500 CFM turbo, because the engine is only capable of accepting 460 CFM of flow at 17 psi.
At 3000 - 4000 rpm the engines air flow requirement falls right in the sweet spot of the stock turbos compressor map and the turbo will supply all the air the engine will accept at those rpms and max pressure for the turbo which is about 24 psi boost. (of course you may detonate like crazy at that boost and kill the engine, but the turbo is ready willing and able in that rpm range)
The guys who have run Delta Dash logs have shown that the actual manifold pressure is a lot lower than your boost gauge reads. The gauge just does not read fast enough to show the huge down turn in pressure, because you are only at 7000 rpm for a half a second or so, under max acceleration. Even a VF22 won't hold 17 psi at red line, all though the boost gauge tells you it does.
Yes the weak point in the stock WRX motor is the ability of the valves, heads, cams and intake/exhaust manifold to breath. The engine only flows at 80%+ VE at red line, the RA spec C engine which has much better head design with the AVCS cams flows at about 93% VE at 7000 rpm.
The biggest single problem is the stock cams are relatively mild cams. Once you improve the cams then you need porting and valve work to get higher rpm and breathing at high rpm. The stock intake and exhaust manifolds are fair to good. The stock exhaust works well up into the high 300 hp range, and gives excellent low end torque. Headers are showing their value at high rpm, but typically reduce low end torque enough that many folks go back to stock exhaust manifolds to get back around the town driveability.
Larry
08-04-2003 | 02:09 PM
#15
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Re: details
Originally posted by hotrod
The TD04-13G is rated at a max flow of 360 CFM at 17 psi, but can hold only about 11 psi, at 7000 rpm on our 2 L engine because the engine wants more flow than it can provide (ie about 460 CFM at 85% VE and a pressure ratio of 2.18 -- 17 psi). It can support almost 24 psi at 3000- 4000 rpm.
http://www.stealth316.com/images/td04-13g-raw.gif
If you put a 16G compressor on the TD04 you'd strangle the engine on exhaust back pressure, it has a 6cm exhaust side, and the stock exhaust side for the 16G is a 7 cm.
360 CFM works out to a crank shaft power out of about 250 hp, if you over spin the turbo you can get up in the neighborhood of 280 but your effeciency is terrible and the air charge will be quite hot -- like over 350 deg F --- can you say "detonation territory" ?
The stock injectors can handle all the air flow out of the stock turbo especially if you run a high density race gas.
Larry
The TD04-13G is rated at a max flow of 360 CFM at 17 psi, but can hold only about 11 psi, at 7000 rpm on our 2 L engine because the engine wants more flow than it can provide (ie about 460 CFM at 85% VE and a pressure ratio of 2.18 -- 17 psi). It can support almost 24 psi at 3000- 4000 rpm.
http://www.stealth316.com/images/td04-13g-raw.gif
If you put a 16G compressor on the TD04 you'd strangle the engine on exhaust back pressure, it has a 6cm exhaust side, and the stock exhaust side for the 16G is a 7 cm.
360 CFM works out to a crank shaft power out of about 250 hp, if you over spin the turbo you can get up in the neighborhood of 280 but your effeciency is terrible and the air charge will be quite hot -- like over 350 deg F --- can you say "detonation territory" ?
The stock injectors can handle all the air flow out of the stock turbo especially if you run a high density race gas.
Larry
However, you'll be porting the entire turbo system, including the exh. manifold, up, down, and both the compressor housing and exhaust on the turbo. This effectively opens the 6cm outlet to about 6.7cm, while increasing flow efficiency due to the mirror finish that a good port will give you.
This includes the all important wastegate bypass, which helps hold boost psi constant without dangerous spikes. When both this and the turbo exhaust is ported, it runs very well with minimal backpressure issues all the way to mid 300hps. A properly ported TD04 functions remarkably similar to a TD05, without the drawback of having different exhaust flanges and the intake outlet pointing the wrong way. Although theoretically your spool up time will increase, I noticed very little initial increase, but it will shift your torque curve to the right, which increases horsepower and increases your torque rpm peak. So instead of reaching full torque at 4,000 rpms, it'll be more like 4,600 rpms.
And Larry, race gas is like 3.50 a gallon!! No thank you.
There's a blue RS up here in Fort Collins that's running the exact system I'm speaking of, who blew me and my ported TD04 13G with 255hp off the road!!
The $400 I'm speaking of is $100 for the wheel, and $200 for balancing and turbo rebuilding (you can't just slap a new wheel in there and expect it to spin perfectly.) Porting maybe $100? I ported my own pipes and turbo, so I don't know the exact cost of that. If you lived closer I could have this done for you in a week, but let me know if you're interested, I could hunt down the wheel from a DSM site.
7
Last edited by impreza7; 08-04-2003 at 02:40 PM.