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This is a discussion on Boost & HP Level in the Forced Induction forum
I read on here a lot how you shouldnt shoot for a boost level but a power level. I've also read alot that conflicts with this though. Here's my question: There's a few boosted F22's out there making 300ish WHP. If I'm running 12psi, and ...
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|07-28-2006, 11:48 AM||#1|
Boost & HP Level
I read on here a lot how you shouldnt shoot for a boost level but a power level. I've also read alot that conflicts with this though.
Here's my question:
There's a few boosted F22's out there making 300ish WHP. If I'm running 12psi, and I make 250whp, could I increase boost to 14-15psi to try and make 300 safely? That's not too much boost for a stock block to handle?
|07-28-2006, 01:01 PM||#8|
Maybe theory was the wrong word, I didnt mean it in any kind of negative way
I'm going to try and run 15psi when I get the new clutch next week. A guy on another site is running a T3/T4 at 14.5psi daily and claims no issues after a bunch of miles. That had me thinking about what we're talking about here and I just wanted to hear some reasoning behind it.
|07-28-2006, 01:51 PM||#9|
how many miles are on the motor again?
and how many miles on the headgasket? and do you know if its a stock head gasket or not?
once you start getting up there towards 300hp you might want to consider a 3 layer metal head gasket, new timing belt and water pump, and some arp head studs...
|07-28-2006, 03:06 PM||#11|
lol, go and crank away
they are stong motors...
i have yet to see one thats tossed a rod
just beware if your temps start to rise or you get white smoke...
as long as you don't overheat or run it with water in the oil you won't hurt anything
and if you do pop the head gasket it'll give you a reason to get a 3 layer, some ARP's, and a hondata intake manifold gasket...
and a DIY PnP on the head too
i like seeing your progress...
i was going to start wiring the wideband etc last night but got involved with helping a friend lower an S10 so my evening was shot...
saturday is a dedicated setup and tuning day... wooo hooo
"Highly psychotic and extremely violent."
|07-29-2006, 08:15 PM||#15|
|07-31-2006, 10:25 AM||#20|
I'll see if I can find it.
Here's what a guy wrote on MatrixOwners, we were talking about the same topic. Only difference there is, there's only like 4 or 5 people that actually have or have had a turbo car. Not a whole lot of knowledge on FI but makes for "interesting" reading.
Quote from LHO-RTS:
OK here is the deal with this:
Boost is boost, no matter how big the turbo is. If you have a big turbo making 4 psi, it will make the same power as a small turbo making 4 psi. The size of turbo does not effect power if the boost is exactly the same.
I have proven this with my 94 cavy turbo. I had a smaller t3 KKK K26 turbo that made my car run a 14.85 1/4 mile when it was setup at 4psi boost. I ran the exact same time, 14.85 1/4 mile with the current turbo i'm running which is a HUGE-a** GM5 turbo from a 6.5L diesel, and i was running, you guessed it, only 4 psi boost.
Boost is boost, you will get the same amount of power from the same level of boost no matter what size the turbo is.
The main diff from large to small turbos is where the power comes in and where it falls off.
So I wrote back:
Case re-opened, this is SO NOT TRUE! Please dont post info thats so friggin false its not even funny.
A. Now that you have a Mack truck turbo it takes longer to spool it up, thus making slower launches with better top end. Kinda equals itself out.
Let's not compare drag times as power examples, thats just shooting in the dark. If you have a dyno comparison then show it.
If a T3 makes 300cfm at 4psi and a T25 only makes 200cfm at 4psi, you're trying to tell me that will be the same power? I think not mang. Thats why people buy big a$s turbos, higher HP
^^ No man, I took fluid dynamics in school.
You must understand, 4 psi is 4 psi going into the engine. It doesn't matter what is putting it in there. 4psi from a larger turbo just means there is more volume and less velocity.
And don't rag on a car you've never seen. My cavy actually has no lag that way it setup. I have the vids to prove it!! I got the turbo for free and decided to throw it on for run. The reason it only make 4psi is that it is too inefficient for the engine. Its on an engine with less than have the displacement of the engine the turbo came off of. The V6 simply doen't have the exhaust pressure to spool it fast enough to make more than 4-5psi.
When you read a boost gauge it's taking the reading from the intake manifold pressure, correct? So if the pressure in the manifold is the same, the engines power will be the same.
I finished the debate with:
An engine is a air/fuel pump, the more air/fuel you get in there the more power you make.
If you have 200cfm of air and the correct amount of fuel, you'll make 200whp(VERY GENERAL ASSUMPTIONS HERE)
If you have 300cfm of air and the correct amount of fuel, you'll make 250+whp.
The more air/fuel you cram in there and correctly ignite, the MORE POWER IS MADE. SO, the size of the turbo directly effects the power output.
|07-31-2006, 10:34 AM||#21|
thats basically what you should have said. he is just spouting shit that he heard someone else say...you wonder why there are single turbo supras making 800HP at 28 psi, and there are 600 horsepower supras running at 28 psi?
|07-31-2006, 10:42 AM||#22|
He claims he has a degree in Fluid Dynamics Degree or not, he's WAY off.
This is his last post:
cfm is a FLOW measurement, NOT a PRESSURE measurement. Don't mix em up. And psi is not just a number. Its POUNDS PER SQUARE INCH. If you have a volume (your intake manifold) and you have 5 psi of air in there, it's the same 5 psi regardless of the size of turbo. If you have a large turbo at 5 psi boost, the flow THROUGH the INTAKE MANIFOLD will be the same as the flow THROUGH the INTAKE MANINFOLD at 5 psi boost from a small turbo.
Here is the diff two turbos, same boost pressure, assuming same size intake piping intercooler and throttle body and intake manifold;
Large turbo: doesn't have to spool as fast as the smaller turbo, larger compressor housing, less velocity, same volume, as soon as the air exits the turbo and enters the rest of the intake piping and intake manifold same flow!
Small turbo: has to spool faster, smaller compressor housing, same volume through smaller compressor = more velocity, as soon as air enters same intake tract as large turbo, SAME FLOW!!!
Dude, what i'm saying is you WILL get the SAME POWER at the SAME BOOST LEVEL with any turbo.
Lets say 10psi makes 250whp on whatever car with a smaller turbo. If you install a larger turbo and run 10psi, it will still make 250whp, just at a different rpm.
Think about it man!
I came back with this:
LHO, So why are there all of these compressor maps and different sized turbos man? They all make the same power why have choices?
PLEASE sit back and think about what you're saying because its way off. If you want to make drag comparisons, Wish100K was running a T25 at 8psi, it took him like 17 seconds to get to 100. Then he switched out to a Big16G equivelent, it only took 12-13 seconds to get to 100 at the same boost level. Cant be possible right, same boost level, same HP I think not man. I'm sorry but you're wrong here.
you said 5psi in the intake manfiold is 5psi, thats true, but the volume is NOT the same.
Take a 2 liter Pepsi bottle and pressure it to 5psi, then do the same with a spackle bucket. You're saying the Pepsi bottle has the same volume as the spackle bucket? NO FRIGGIN WAY! MORE AIR = MORE POWER!!!
Last edited by Turbo&Auto; 07-31-2006 at 10:45 AM.
|07-31-2006, 11:33 AM||#23|
4 psi IS 4 psi.
but it is NOT Directly proportional to CFM. and CFM is the actual volume of air getting into the motor.
psi is the RESISTANCE of the air NOT getting into the motor.
he can take his fluid dynamics degree and shove it up his non real world experience asss :P
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