Forced Induction Superchargers | Turbochargers | Intercoolers

So 15lbs of boost isnt 15lbs of boost?

Thread Tools
 
Search this Thread
 
Old Jun 6, 2006 | 11:36 AM
  #1  
Camaro_Zach's Avatar
Thread Starter
TECH Fanatic
20 Year Member
iTrader: (19)
 
Joined: Sep 2002
Posts: 1,531
Likes: 1
From: Chicago
Default So 15lbs of boost isnt 15lbs of boost?

So with my dinky 50 trims making 15 lbs of boost...thats not the same as say twin 67's making 15 lbs of boost?

can someone explain this to me or what...cause i see guys making 700+ rwhp on like 9 lbs of boost, then other situations where people are making 13+ lbs of boost with the same hp.
Reply
Old Jun 6, 2006 | 11:41 AM
  #2  
JZ 97 SS 1500's Avatar
LS1TECH Sponsor
iTrader: (2)
 
Joined: Aug 2002
Posts: 2,725
Likes: 0
From: Huntsville, AL
Default

The difference is just efficiency.

Jose
Reply
Old Jun 6, 2006 | 11:44 AM
  #3  
Camaro_Zach's Avatar
Thread Starter
TECH Fanatic
20 Year Member
iTrader: (19)
 
Joined: Sep 2002
Posts: 1,531
Likes: 1
From: Chicago
Default

i always thought it was manifold pressure...so no matter how hard/easy the turbos had to work...the manifold saw 15 lbs of pressure...how it built it didnt matter.

i realize im wrong lol.

so what two turbos would reach close to 800 rwhp "easily" what efficiency turbos would do the job. i see guys hittin 700+ on pump gas.

also how much of this is attributed to the plumbing? will too small/large pipes and too many bends cause issues with efficency?
Reply
Old Jun 6, 2006 | 01:58 PM
  #4  
Navy David SS's Avatar
TECH Veteran
iTrader: (13)
 
Joined: Nov 2001
Posts: 4,647
Likes: 1
From: Sioux Falls, SD
Default

My twin T-67's will do close to 800 each. On just 8lbs it did 635rwhp; on 17lbs (blowing the tires off on the dyno) they did 875RWHP. 18-20lbs will give us the 1,000 we are looking for.

All of the SS's set up is one off. No kit.

David
Reply
Old Jun 6, 2006 | 02:08 PM
  #5  
JZ 97 SS 1500's Avatar
LS1TECH Sponsor
iTrader: (2)
 
Joined: Aug 2002
Posts: 2,725
Likes: 0
From: Huntsville, AL
Default

Originally Posted by Camaro_Zach
i always thought it was manifold pressure...so no matter how hard/easy the turbos had to work...the manifold saw 15 lbs of pressure...how it built it didnt matter.

i realize im wrong lol.

so what two turbos would reach close to 800 rwhp "easily" what efficiency turbos would do the job. i see guys hittin 700+ on pump gas.

also how much of this is attributed to the plumbing? will too small/large pipes and too many bends cause issues with efficency?
IF you are trying to build a kit for a true race car to make the most power from the setup you can then you calculate all parameters for max efficiency. So you start with compressor maps, then piping diameters, bends and velocity. Also you look at intercooler endtank design...etc..etc.

Now for most kits just match the turbos properly to your desired boost pressure and you will see the numbers you are looking for. You need to post your engine combo to match the turbos. That changes things as well.

Jose
Reply
Old Jun 6, 2006 | 02:21 PM
  #6  
mahhddgtp's Avatar
TECH Enthusiast
 
Joined: Mar 2004
Posts: 604
Likes: 0
From: Loganville, GA
Default

All depends on how much air you flow and how well the motor itself flows....

12psi with a big turbo will yield you more power than lets say 12psi with a small turbo would... Why? You're moving more air with the larger turbo

You'll see a drop in boost if you get a larger intake mani or exhaust manifold. Why? It helps the engine flow more.... Less pressure is being built up in the IM, and more of the air is going into your engine... That's what you want....

Plumbing/intercooler(s) have a play in it too.. Like Jose said... efficiency.
Reply
Old Jun 6, 2006 | 02:43 PM
  #7  
smokinHawk's Avatar
TECH Senior Member
iTrader: (48)
 
Joined: Jan 2002
Posts: 7,354
Likes: 1
From: Columbus, ohio
Default

Originally Posted by mahhddgtp
12psi with a big turbo will yield you more power than lets say 12psi with a small turbo would... Why? You're moving more air with the larger turbo
.
Thats only if your engine size is different the restriction is the tubing and then engine then exhaust which will determin the boost most likely.

just think of it as colder air makes more power then hotter air because that air is denser, easiest way to think of effeicency.
Reply
Old Jun 6, 2006 | 04:57 PM
  #8  
family sedan's Avatar
On The Tree
iTrader: (3)
 
Joined: Nov 2004
Posts: 178
Likes: 0
From: Park Ridge, IL (Borders Chicago)
Default

Air + Fuel = Power.

Simple as that.
Reply
Old Jun 6, 2006 | 05:13 PM
  #9  
muncie21's Avatar
TECH Enthusiast
iTrader: (14)
 
Joined: Apr 2005
Posts: 591
Likes: 0
From: NE Ohio
Default

Boost pressure is an indication of flow restriction or back pressure. How much air flowing 'through' the engine is a better predictor of horsepower than boost pressure.
Reply
Old Jun 6, 2006 | 05:35 PM
  #10  
Boostaholic's Avatar
TECH Addict
iTrader: (4)
 
Joined: Sep 2002
Posts: 2,542
Likes: 0
From: Boise, ID
Default

15lbs of boost @ 190deg F vs 15lbs of boost @ 100deg F?
Reply
Old Jun 6, 2006 | 05:56 PM
  #11  
JZ 97 SS 1500's Avatar
LS1TECH Sponsor
iTrader: (2)
 
Joined: Aug 2002
Posts: 2,725
Likes: 0
From: Huntsville, AL
Default

Originally Posted by Boostaholic
15lbs of boost @ 190deg F vs 15lbs of boost @ 100deg F?

A relatively stock headed 346 CI engine revving to 6500rpms at 15psi running a compressor effic. of 70% for both units would net around ~820hp at 190 inlet temps.

For the engine running 100deg inlet's it would net around ~955hp.


Jose
Reply
Old Jun 6, 2006 | 05:58 PM
  #12  
Camaro_Zach's Avatar
Thread Starter
TECH Fanatic
20 Year Member
iTrader: (19)
 
Joined: Sep 2002
Posts: 1,531
Likes: 1
From: Chicago
Default

Originally Posted by family sedan
Air + Fuel = Power.

Simple as that.


hahahaha honestly way to not answer my question at all. we know you need air and gas to create an explosion. thanks. roger. check. did you even read the posts prior to making yours? hahah
Reply
Old Jun 6, 2006 | 06:00 PM
  #13  
Camaro_Zach's Avatar
Thread Starter
TECH Fanatic
20 Year Member
iTrader: (19)
 
Joined: Sep 2002
Posts: 1,531
Likes: 1
From: Chicago
Default

i wish i knew wtf these tti turbos were so you could do the efficiency on em haha. i know its 15 lbs of boost at peak of 111 inlet temp.
Reply
Old Apr 7, 2009 | 10:08 PM
  #14  
crazymofo1986's Avatar
12 Second Club
iTrader: (3)
 
Joined: Mar 2004
Posts: 330
Likes: 0
From: florida
Default

look at it this way to. my buddy has a jetta and another gti there pushing 15 lbs. and there slow. lbs has no relavsion to hp. dont quote me on that tho,
Reply
Old Apr 7, 2009 | 10:55 PM
  #15  
TARZAN's Avatar
11 Second Club
20 Year Member
iTrader: (12)
 
Joined: Dec 2003
Posts: 1,312
Likes: 0
From: Memphis Area
Default

Originally Posted by JZ 97 SS 1500
A relatively stock headed 346 CI engine revving to 6500rpms at 15psi running a compressor effic. of 70% for both units would net around ~820hp at 190 inlet temps.

For the engine running 100deg inlet's it would net around ~955hp.


Jose
This is probably the best way to look at it, to help him really understand....its easier than trying to explain when you say "efficiency", because not everybody understands what an efficient turbo does better lol, or why for that matter.

-Will
Reply
Old Apr 7, 2009 | 11:09 PM
  #16  
ItsNotStock's Avatar
TECH Regular
iTrader: (24)
 
Joined: Aug 2007
Posts: 446
Likes: 0
From: Billings, Montana
Default

This thread is old...
Reply
Old Apr 7, 2009 | 11:19 PM
  #17  
Frost's Avatar
FormerVendor
iTrader: (45)
 
Joined: Jul 2005
Posts: 5,913
Likes: 2
From: Richmond VA
Default

Originally Posted by crazymofo1986
look at it this way to. my buddy has a jetta and another gti there pushing 15 lbs. and there slow. lbs has no relavsion to hp. dont quote me on that tho,


Look at it this way; this thread is like three years old...
Reply
Old Apr 8, 2009 | 06:35 AM
  #18  
Somebody09's Avatar
TECH Resident
 
Joined: Dec 2004
Posts: 905
Likes: 0
Default

Originally Posted by crazymofo1986
look at it this way to. my buddy has a jetta and another gti there pushing 15 lbs. and there slow. lbs has no relavsion to hp. dont quote me on that tho,
What's a relavsion?
Reply
Old Apr 8, 2009 | 08:03 AM
  #19  
sujomatt's Avatar
TECH Resident
iTrader: (7)
 
Joined: Dec 2008
Posts: 796
Likes: 0
From: CT
Default

i think he was saying relation?
Reply
Old Apr 8, 2009 | 08:12 AM
  #20  
cablebandit's Avatar
9 Second Club
20 Year Member
iTrader: (37)
 
Joined: Nov 2001
Posts: 7,903
Likes: 1
From: Cleveland, OH
Default

my incons took 15psi to make 735rwhp....my s488 only takes 7.5psi to do that.
Reply



All times are GMT -5. The time now is 01:51 PM.