SnailOnARampage
Senior Member
That is meant to be taken in with everything i mentioned above, assuming that there is something letting the air out of the manifold once it reaches 10 psi.
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Gsr Turbo?
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That is meant to be taken in with everything i mentioned above, assuming that there is something letting the air out of the manifold once it reaches 10 psi.
Originally posted by SnailOnARampage@Mar 17 2003, 03:54 AM
full throttle and 10 psi means that the engine cannot take in anymore cf/m
correct, BUT there is still a hell of a lot more air going in in the first place.
SnailOnARampage
Senior Member
Yeah the larger turbo has the ability to pump more air into the engine, provided you need it. But if two turbos are able to pump the same amount of air into engine (at a given temperature, RPM and throttle position) they will be increasing the horsepower by the same amount. However, when you either increase the psi (cap) or increase the engines ability to use more cf/m (either by increasing displacement or RPM), the smaller turbo will be unable to keep the same MAP as the larger one. But, if you put a cap both turbos below their maximum load, the smaller turbo will be faster due to the reasons I explained above.
SnailOnARampage
Senior Member
So....what turbo will be faster actually depends on the size of the turbo vs displacement/rpms of the engine rather than the actual size of the turbo (provided there is some kind of cap on the intake manifold pressure).
SnailOnARampage
Senior Member
bigger is only better if you can use the excess that the larger turbo creates
SnailOnARampage
Senior Member
when you do your dyno at 10 psi (in the exhaust) it is quite possible that you can hit 400 whp, but the intake manifold pressure has to be a lot higher than 10 psi (at full throttle). The intake manifold pressure would have to be something like 22 psi (assuming the air was a normal temperature) in order to reach 400 whp on a semi stock GSR.
well, first of all, there is no psi in the exahust. the exahust is not part of the vacuum system. the intake manifold pressure is what is sent back to the waste gate via a vacuum hose to control boost level.
using a boost controller simply leaks out some of this to "fool" the gate into seeing a lesser pressure, but in fact it is more, as measured at the i. manifold.
using a boost controller simply leaks out some of this to "fool" the gate into seeing a lesser pressure, but in fact it is more, as measured at the i. manifold.
SnailOnARampage
Senior Member
ah good info. I didn't know that.
SnailOnARampage
Senior Member
Okay, now that I understand how a bov/waste gate works i'm not quite as dumb as I was yesterday.
However:
For Honda's mystical b07a DOHC VTEC engine which, unboosted moves 100 cf/m @ 7600 rpms. When you add the 14g turbo to it which @ 14.7 psi moves 200 cf/m(lets pretend) and set the wastegate or whatever to 14.7 psi, the engine is getting almost exactly twice as much air (ignoring loss caused by friction or constriction or whatever), hence making twice as much torque.
Now, when you strap that big ass t88 on that engine and set the wastegate to 14.7 psi you are still pushing 200 cf/m into that engine and still making only twice as much torque. the only difference is you have a ton of lag, which makes it so you dont see the power in every day driving, and you lose a lot of energy (horsepower) turning a turbo which you are only using to 40 percent capacity.
above is why I said this:
However 10psi of air at a given temperature at the map sensor on a given engine at given RPM at full throttle from a 14g and a t88 will make the same amount of horsepower.
Now, when you switch over to honda's mystical b11a DOHC VTEC engine which moves 150 cf/m @ 7600 rpm, you will get more power out of the t88 than the 14g in the high end, because the t88 is still capable of pushing the full 14.7 psi (now equalling 300 cf/m, which is 60 pecent capacity), while the 14g is only able to maintain just under 5 psi @ full throttle @ 7600 rpms...even though the wastegate is set to 14.7, its only running at 5 psi, and only making 1.3x more peak torque than stock, while the t88 is still making a full 100 pecent increase.
In a situation like the one above, the t88 is still too big, and the 14g is too small, so you would want to go and get a t3/t4 or something which moves 300 cf/m @ 14.7 psi. Now what is going to be the difference in HP between the two? The t3/t4 will be a lot better for daily driving, and will actually be faster than the t88, because of less energy being put into turning the turbo. The ONLY way the t88 would be faster on this setup, is if you either set the wastegate to a higher pressure, or increase the displacement/rpms of the engine.
So, the only time my original, now very flamed, post is NOT true is if one of the turbos is too small to push the cf/ms required by the engine @ 10 psi. The post is ALWAYS true provided that the 10 psi is being read at the MAP sensor.
However:
For Honda's mystical b07a DOHC VTEC engine which, unboosted moves 100 cf/m @ 7600 rpms. When you add the 14g turbo to it which @ 14.7 psi moves 200 cf/m(lets pretend) and set the wastegate or whatever to 14.7 psi, the engine is getting almost exactly twice as much air (ignoring loss caused by friction or constriction or whatever), hence making twice as much torque.
Now, when you strap that big ass t88 on that engine and set the wastegate to 14.7 psi you are still pushing 200 cf/m into that engine and still making only twice as much torque. the only difference is you have a ton of lag, which makes it so you dont see the power in every day driving, and you lose a lot of energy (horsepower) turning a turbo which you are only using to 40 percent capacity.
above is why I said this:
However 10psi of air at a given temperature at the map sensor on a given engine at given RPM at full throttle from a 14g and a t88 will make the same amount of horsepower.
Now, when you switch over to honda's mystical b11a DOHC VTEC engine which moves 150 cf/m @ 7600 rpm, you will get more power out of the t88 than the 14g in the high end, because the t88 is still capable of pushing the full 14.7 psi (now equalling 300 cf/m, which is 60 pecent capacity), while the 14g is only able to maintain just under 5 psi @ full throttle @ 7600 rpms...even though the wastegate is set to 14.7, its only running at 5 psi, and only making 1.3x more peak torque than stock, while the t88 is still making a full 100 pecent increase.
In a situation like the one above, the t88 is still too big, and the 14g is too small, so you would want to go and get a t3/t4 or something which moves 300 cf/m @ 14.7 psi. Now what is going to be the difference in HP between the two? The t3/t4 will be a lot better for daily driving, and will actually be faster than the t88, because of less energy being put into turning the turbo. The ONLY way the t88 would be faster on this setup, is if you either set the wastegate to a higher pressure, or increase the displacement/rpms of the engine.
So, the only time my original, now very flamed, post is NOT true is if one of the turbos is too small to push the cf/ms required by the engine @ 10 psi. The post is ALWAYS true provided that the 10 psi is being read at the MAP sensor.
SnailOnARampage
Senior Member
Originally posted by Ractive78@Mar 17 2003, 06:17 AM
If you guys are done arguing, could you give some advice, on the fuel system I should use, and which turbo would work best? "With the gsr motor" Do you know of any dyno places in Virginia " close to Waynesboro if possible"?
And what is a good boost controler, to use?
Hondata is apparently the best, however I have no experience with any of them. As for the boost controller, I could not tell you
Originally posted by SnailOnARampage@Mar 17 2003, 08:21 AM
For Honda's mystical b07a DOHC VTEC engine which, unboosted moves 100 cf/m @ 7600 rpms. When you add the 14g turbo to it which @ 14.7 psi moves 200 cf/m(lets pretend) and set the wastegate or whatever to 14.7 psi, the engine is getting almost exactly twice as much air (ignoring loss caused by friction or constriction or whatever), hence making twice as much torque.
Now, when you strap that big ass t88 on that engine and set the wastegate to 14.7 psi you are still pushing 200 cf/m into that engine and still making only twice as much torque. the only difference is you have a ton of lag, which makes it so you dont see the power in every day driving, and you lose a lot of energy (horsepower) turning a turbo which you are only using to 40 percent capacity.
for the 6th time, it doesn't work this way.
So, the only time my original, now very flamed, post is NOT true is if one of the turbos is too small to push the cf/ms required by the engine @ 10 psi. The post is ALWAYS true provided that the 10 psi is being read at the MAP sensor.
10 psi is 10 psi. it is PRESSURE. it is not the AMOUNT of air.
fill a 10-speed skinny ass bike tire up. it takes like 30 psi to make it "hard" to the touch.
fill a mtn bike knobby tire up with 30 psi, until it is hard.
tell me, which one has more air in it? the mtn bike - cuz its wider and has more area to fill before it starts gain pressure- in other words, more volume.
with that in mind, go back to the article i linked above where i describe volume vs mass.
Originally posted by SnailOnARampage+Mar 17 2003, 08:22 AM-->Ractive78@Mar 17 2003, 06:17 AM
If you guys are done arguing, could you give some advice, on the fuel system I should use, and which turbo would work best? "With the gsr motor" Do you know of any dyno places in Virginia " close to Waynesboro if possible"?
And what is a good boost controler, to use?
We aren't arguing. in fact, this is turning into a very knowledgeable thread- one that you should be reading.
there is No such thing as wht turbo works best.
there is however, which turbo works best for what YOU want the car to do. so please, tell us what you want, potential peak power, and most of all, your budget.
fuel system, that depends on how big or small you go.
virginia? check out our locator in the referece section, or perhaps go to a local board- dragva.com someone there could probably point you in the right direction of a dyno shop.
boost controller - they all work pretty good.
Apex AVC-r
greddy profec B
greddy e-01
blitz DD
are all in my possibility list. they all cost about the same, and all sport pretty much the same features.
SnailOnARampage
Senior Member
Originally posted by pissedoffsol+Mar 17 2003, 06:35 AM-->SnailOnARampage@Mar 17 2003, 08:21 AM
For Honda's mystical b07a DOHC VTEC engine which, unboosted moves 100 cf/m @ 7600 rpms. When you add the 14g turbo to it which @ 14.7 psi moves 200 cf/m(lets pretend) and set the wastegate or whatever to 14.7 psi, the engine is getting almost exactly twice as much air (ignoring loss caused by friction or constriction or whatever), hence making twice as much torque.
Now, when you strap that big ass t88 on that engine and set the wastegate to 14.7 psi you are still pushing 200 cf/m into that engine and still making only twice as much torque. the only difference is you have a ton of lag, which makes it so you dont see the power in every day driving, and you lose a lot of energy (horsepower) turning a turbo which you are only using to 40 percent capacity.
for the 6th time, it doesn't work this way.
So, the only time my original, now very flamed, post is NOT true is if one of the turbos is too small to push the cf/ms required by the engine @ 10 psi. The post is ALWAYS true provided that the 10 psi is being read at the MAP sensor.
10 psi is 10 psi. it is PRESSURE. it is not the AMOUNT of air.
fill a 10-speed skinny ass bike tire up. it takes like 30 psi to make it "hard" to the touch.
fill a mtn bike knobby tire up with 30 psi, until it is hard.
tell me, which one has more air in it? the mtn bike - cuz its wider and has more area to fill before it starts gain pressure- in other words, more volume.
with that in mind, go back to the article i linked above where i describe volume vs mass.
Isnt 14.7 psi @ 150 cf/m the same thing as 300 cf/m?
SnailOnARampage
Senior Member
I am fully aware of the difference between pressure and the number of oxygen molecules being forced into an engine. I am saying that at a given temperature, at twice the air pressure, there will be twice as many oxygen molecules, hence twice as much torque.
Originally posted by SnailOnARampage@Mar 17 2003, 08:55 AM
I am saying that at a given temperature, at twice the air pressure, there will be twice as many oxygen molecules, hence twice as much torque.
the problem with this, is that it is not directly related.
twice the air pressure does NOT mean twice the amount of air flow
SnailOnARampage
Senior Member
A prime example for that is: put a little water in an empty steel campstove fuel container, heat the container until the water boils and moves all of the regular air out of the container, then put the lid back on. When the container is still hot, the water vapor has more energy(heat), causing more pressure on the walls of the inside of the container. As the water cools the pressure decreases and the thing slowly collapses, even though there were always the same amount of atoms in the container.
SnailOnARampage
Senior Member
Originally posted by pissedoffsol+Mar 17 2003, 06:57 AM-->SnailOnARampage@Mar 17 2003, 08:55 AM
I am saying that at a given temperature, at twice the air pressure, there will be twice as many oxygen molecules, hence twice as much torque.
the problem with this, is that it is not directly related.
twice the air pressure does NOT mean twice the amount of air flow
so is it going to be more than twice or less than twice? I am thinking less than twice.
SnailOnARampage
Senior Member
How would twice the pressure equal 3x the air flow? like in your 400 whp 10 psi dealy
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