Bigger turbo give more HP at same PSI as a smaller turbo?
07-15-2006, 06:13 AM
#1
Honda-Tech Member
Thread Starter
Join Date: Aug 2001
Location: Fort Worth, TX, USA
Posts: 1,842
Likes: 0
Received 0 Likes
on
0 Posts
Bigger turbo give more HP at same PSI as a smaller turbo?
I'm trying to see if I understand this compressor map thing.
Basically it works that to get a certain PSI the turbo has to provide the air flow of the engine itself and then a pressure ratio to that. For instance theoretically to get 14.7 PSI a turbo would have to provide a pressure ratio of 2.0 at a certain volume flow. So if a big turbo and a small turbo can both provide say 400 CFM for 14.7 PSI on an engine and they are both operating in efficiency islands that makes the air the same temps, then really they should both dyno around the same right?
Now if the small turbo is able to provide that 400 CFM, but its at like a 68% efficiency range and the big turbo can do it at 78%, then the bigger turbo is able to deliver a denser air and thus more fuel can be mixed in for more power. Right?
Basically it works that to get a certain PSI the turbo has to provide the air flow of the engine itself and then a pressure ratio to that. For instance theoretically to get 14.7 PSI a turbo would have to provide a pressure ratio of 2.0 at a certain volume flow. So if a big turbo and a small turbo can both provide say 400 CFM for 14.7 PSI on an engine and they are both operating in efficiency islands that makes the air the same temps, then really they should both dyno around the same right?
Now if the small turbo is able to provide that 400 CFM, but its at like a 68% efficiency range and the big turbo can do it at 78%, then the bigger turbo is able to deliver a denser air and thus more fuel can be mixed in for more power. Right?
07-15-2006, 06:22 AM
#2
Honda-Tech Member
Thread Starter
Join Date: Aug 2001
Location: Fort Worth, TX, USA
Posts: 1,842
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (Westrock2000)
basically what I'm asking is as long as the required amount of air volume is being supplied and the air density is the same, the engine doesn't care what kind of a turbo it comes from right?
07-15-2006, 08:49 AM
#3
Member
Join Date: May 2004
Location: Nashville, TN, U.S.A
Posts: 2,992
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (Westrock2000)
That is correct for one part of the equation. There are a lot more like ball bearing efficiencies and technology of the wheel, but those are small compared to volumetric efficiency. The smaller turbo will of course cause a greater exhaust "restriction" lowering the volumetric efficiency of the engine in the higher RPM or large displacment. This is probably the greatest reason why a smaller turbo generates less HP at XX PSI then a larger turbo at the same XX PSI.
11-23-2006, 09:07 PM
#4
Honda-Tech Member
Join Date: Apr 2006
Location: thread hijacker, SNJ
Posts: 855
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (adseguy)
rather than start a new thread ill resurrect this one
so if you push the same psi of a bigger one, you get more hp
this in turn puts more strain on your engine correct?
to rephrase... you aren't "unlocking" hidden engine potential with a bigger turbo
you are just raising the bar on how far you can push it... correct?
lets just say a small turbo 10psi = 7psi on a bigger one
both create the same hp and put the same stress on your engine
am i correct?
so if you push the same psi of a bigger one, you get more hp
this in turn puts more strain on your engine correct?
to rephrase... you aren't "unlocking" hidden engine potential with a bigger turbo
you are just raising the bar on how far you can push it... correct?
lets just say a small turbo 10psi = 7psi on a bigger one
both create the same hp and put the same stress on your engine
am i correct?
11-26-2006, 08:41 PM
#7
Honda-Tech Member
Join Date: Oct 2006
Location: Lovin the EF, Wa
Posts: 4,420
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (dafuzzbudd)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dafuzzbudd »</TD></TR><TR><TD CLASS="quote">does a bigger turbo make the air cooler?</TD></TR></TABLE>
no.
no.
Trending Topics
11-26-2006, 08:44 PM
#8
Join Date: Sep 2003
Location: C BuS, Ohio, 43146
Posts: 661
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (b00sted-Hatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b00sted-Hatch »</TD></TR><TR><TD CLASS="quote">no.</TD></TR></TABLE> It sort of does... If you take a little turbo and run alot of boost and make it run out of effiency. The small turbo will heat the air more than a larger turbo flowing the same volume of air.
11-26-2006, 08:54 PM
#9
Honda-Tech Member
Join Date: Oct 2006
Location: Lovin the EF, Wa
Posts: 4,420
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (SiKid86)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SiKid86 »</TD></TR><TR><TD CLASS="quote"> It sort of does... If you take a little turbo and run alot of boost and make it run out of effiency. The small turbo will heat the air more than a larger turbo flowing the same volume of air.</TD></TR></TABLE>
allthough that is a bit true he didn't specify anything.
like if you ahd a t3 and boosted 20psi out of it, and compared the t3 to a gt35r at 20psi you'd have a **** load more power jsut because the gt35r forces muchhh more air into the cylinders.
allthough that is a bit true he didn't specify anything.
like if you ahd a t3 and boosted 20psi out of it, and compared the t3 to a gt35r at 20psi you'd have a **** load more power jsut because the gt35r forces muchhh more air into the cylinders.
11-27-2006, 07:18 AM
#11
Honda-Tech Member
Join Date: May 2003
Location: Portland, Oregon
Posts: 5,735
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (aaronISthrowed)
It's the difference between pressure and volume.
It takes air and fuel to make power, and a larger turbo can push a higher volume of air at the same psi.
It's like the difference between a garden hose and a fire hydrant (extreeme example). But basically if both the fire hydrant and the garden hose both flow the same psi the hydrant will be delivering more volume at the same pressure.
If it were air and not water, that added volume could be mixed with an added volume of fuel and the result would be a difference in power output at the same boost level.
And that's not even taking into account the heat differences. That's a whole nother story.
It takes air and fuel to make power, and a larger turbo can push a higher volume of air at the same psi.
It's like the difference between a garden hose and a fire hydrant (extreeme example). But basically if both the fire hydrant and the garden hose both flow the same psi the hydrant will be delivering more volume at the same pressure.
If it were air and not water, that added volume could be mixed with an added volume of fuel and the result would be a difference in power output at the same boost level.
And that's not even taking into account the heat differences. That's a whole nother story.
11-27-2006, 08:16 AM
#12
Honda-Tech Member
Join Date: Jan 2005
Location: Lower Right Hand Corner, PA
Posts: 5,643
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (EJ1 wilcox)
Also, smaller turbo's choke up at higher RPM ranges, which causes the engine to lose a lot of torque. Larger turbo's don't do this, and carry the torque slope further into the RPM range.
Horsepower is derived from torque and RPM, the more torque you make in the 5-8K range the more horsepower your car is going to make.
Horsepower is derived from torque and RPM, the more torque you make in the 5-8K range the more horsepower your car is going to make.
11-27-2006, 11:01 AM
#13
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (EJ1 wilcox)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EJ1 wilcox »</TD></TR><TR><TD CLASS="quote">It's like the difference between a garden hose and a fire hydrant (extreeme example). But basically if both the fire hydrant and the garden hose both flow the same psi the hydrant will be delivering more volume at the same pressure.</TD></TR></TABLE>
Althought Ive always understood and agreed with this type of analogy, the difference is the engine is the same size. PSI is the measurement of air pressure or resistance to cram into the engine. If you hook up a gigantic turbo to that very same engine, its going to encounter the same amount of resistance. I dont see how it can sneak more CFM (volume) into the engine at the same psi (resistance). The engine is the garden hose/hydrant and it did not change. I can't seem to wrap my head around that.
Althought Ive always understood and agreed with this type of analogy, the difference is the engine is the same size. PSI is the measurement of air pressure or resistance to cram into the engine. If you hook up a gigantic turbo to that very same engine, its going to encounter the same amount of resistance. I dont see how it can sneak more CFM (volume) into the engine at the same psi (resistance). The engine is the garden hose/hydrant and it did not change. I can't seem to wrap my head around that.
11-27-2006, 11:49 AM
#14
Member
Join Date: May 2004
Location: Nashville, TN, U.S.A
Posts: 2,992
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (Muckman)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman »</TD></TR><TR><TD CLASS="quote">
Althought Ive always understood and agreed with this type of analogy, the difference is the engine is the same size. PSI is the measurement of air pressure or resistance to cram into the engine. If you hook up a gigantic turbo to that very same engine, its going to encounter the same amount of resistance. I dont see how it can sneak more CFM (volume) into the engine at the same psi (resistance). The engine is the garden hose/hydrant and it did not change. I can't seem to wrap my head around that.</TD></TR></TABLE>
That's cause the analogy IS wrong. It has everything to do with efficiency of the turbo aka how much CFM it can produce within an efficiency range (gasp....a compressor map). I'm assuming that's why manufacturers talk about turbos in CFM not GOD DAMN PSI. The other part of the equation is gas reversion due to turbine restriction. That's about it minus an intercooler.
Althought Ive always understood and agreed with this type of analogy, the difference is the engine is the same size. PSI is the measurement of air pressure or resistance to cram into the engine. If you hook up a gigantic turbo to that very same engine, its going to encounter the same amount of resistance. I dont see how it can sneak more CFM (volume) into the engine at the same psi (resistance). The engine is the garden hose/hydrant and it did not change. I can't seem to wrap my head around that.</TD></TR></TABLE>
That's cause the analogy IS wrong. It has everything to do with efficiency of the turbo aka how much CFM it can produce within an efficiency range (gasp....a compressor map). I'm assuming that's why manufacturers talk about turbos in CFM not GOD DAMN PSI. The other part of the equation is gas reversion due to turbine restriction. That's about it minus an intercooler.
11-27-2006, 12:13 PM
#15
Junior Member
Join Date: Aug 2003
Location: Vacaville, CA, usa
Posts: 76
Likes: 0
Received 0 Likes
on
0 Posts
What ive always stood by is what power you expect out of a certain turbo i believe that 12psi on a basic 50 trim t3/t4 will make more than lets say gt35r because the gt35r is more efficient at a higher amount of boost
11-27-2006, 02:39 PM
#16
Honda-Tech Member
Join Date: Oct 2003
Location: Catching Rivers on Fire TWICE
Posts: 6,281
Likes: 0
Received 0 Likes
on
0 Posts
Re: (Ryan15)
10psi from a gt40r is the same as 10psi from a t25, the reason you make more power from a gt40r is the exhaust housing and its ability to flow. If these 2 turboes are running 10 psi on the same motor the same amount of air is entering the cylinders, just because the compressor is capable of flowing enough air for 800hp doesnt mean it will, for example if you had a gt40r compressor and a t25 turbine/housing it would make the same power psi for psi as a stright t25. It just builds to much back pressure.
11-27-2006, 02:57 PM
#17
Honda-Tech Member
Join Date: Mar 2006
Posts: 1,153
Likes: 0
Received 0 Likes
on
0 Posts
Re: Bigger turbo give more HP at same PSI as a smaller turbo? (adseguy)
Thread
Thread Starter
Forum
Replies
Last Post
dornon13
Forced Induction
135
02-08-2009 04:44 PM
eag36
Forced Induction
11
01-02-2006 07:32 PM
