everone tells me that 3in is the best for the turbo. Dose anyone have a dyno that shows the hp gain for a 2.5 in. to a 3 in.?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by love2xlr8integra &raquo;</TD></TR><TR><TD CLASS="quote">everone tells me that 3in is the best for the turbo </TD></TR></TABLE>

What kind of power are you pushing or wanting to push?

 

I push 540whp through a 2.5in down pipe into a 3in thermal with out a problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HugePistons &raquo;</TD></TR><TR><TD CLASS="quote">I push 540whp through a 2.5in down pipe into a 3in thermal with out a problem. </TD></TR></TABLE>

neat. $1 says u make more with a larger dp without a problem

 

you are probably right but I am two lazy to make another for this car I have made about 5 now keep swiching turbos around.

I wonder how much I would gain??? it at 25psi right now.

 

everone tells me that 3in is the best for the turbo. Dose anyone have a dyno that shows the hp gain for a 2.5 in. to a 3 in.?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VDoP-B18C1 &raquo;</TD></TR><TR><TD CLASS="quote">everone tells me that 3in is the best for the turbo. Dose anyone have a dyno that shows the hp gain for a 2.5 in. to a 3 in.?</TD></TR></TABLE>

That would be a very good comparison.

 

how much 2.5 are we talking about?
with a t3/t4 57trim and 2.5 full at 17lb I made 370 on 93 oct.

then I put on a gt3561e and a 3in cat back at the same boost made 405.

 

dunno if it helps but i got gsr motor t3/to4e 2.5 downpipe to 2.5 straight pipe. no cat, res, or muffler. 290 @9pounds. stock block.

 

A couple years ago Arturbo switched from a 2 3/8" exhaust to a 3" exhaust and gained about 10whp.. This was a turbo gsr w/ revhard kit @ 7.5psi of boost.

 

can i see a dyno sheet. eveyone talks about "so and so" but i want to see it. can any do that or dose everyone just no "so and so" how has gain hp from it....???

 

i don't think anyone has a chart/sheet to compare. unless they own a dyno themselves, it would be pretty spendy to strap onto a dyno everytime you made a change to your car. anyway...i'm running a 2.5"-3" dp, and 3" thermal exhaust...making 300+whp at 10psi. i don't know what i would make with anything smaller but i would guess that my torque numbers would go up a tad bit and my horse power figures would drop.

 

I posted the dyno years ago, but I have to look for it again. I wouldnt say it gained 10whp just to say it. I wouldnt mislead anyone like that. And if anyone knows my car its Direp...

art

 

i would also like to see a dyno caparison with 2.5 piping to 3 cuz everyone keeps telling me to go 3 instead of staying 2.5

 

Assuming that the turbine is an isentropic process, which is really isnt because nothing is 100% efficient, the work that turbine can produce per unit mass is
w = h1 - h2
where w = work per unit mass and h = the enthalpy at each state of the turbine. 1 = before the turbine and 2 = after the turbine. enthalpy is the measure of how much energy a substance has at a given state (certain temperature and pressure) so lets assume Temp remains constant and pressure is the only variable to base enthalpy on. Well the higher the pressure, the higher the enthalpy; the lower the pressure, the lower the enthaply.
There fore the larger the difference in (h1 - h2) the more work the turbine can produce and spin the compressor.
So what we want is a higher pressure on the inlet and a lower pressure on the outlet. we cant really change the inlet pressure, but we can change the outlet pressure by providing less resistance in your exhaust. This can be done by increasing the cross-sectional area of your exhaust and by minimizing the bends and expansions and contractions (from the cat, resonators, etc). Theorectically you make the most power with the largest shortest exhaust.
I could spend another paragraph explaining major and minor losses in the flow of gases or liquids through a system using Bernoulli's eqn, but i have to go pick up my headgasket so i can start putting my motor back together. let me know if you want to hear it
hope this helps
later

 

Well, lets look at it this way. The facet coming out the side of my house has a 2 in. hole to let water out, I hook a 2 in. hose up to it. Now are you saying that if I hook a 3 in. hose up to it, the water will come out faster even though it can only go though a 2 in. hole to start out with?
The second way to look at it is you have a 2 in. hose with water running through then you have a 3 in. PVC pipe that the water is running through, after it comes out of the hose. the water is not going to flow into that 3 in.any faster, then it can come out of the 2 in. hose. all if is going to do is flop in the PVC pipe. It has no reson to take up the hole 3 in. pipe because its coming out of a 2 in. hole to start with.

 

you totally missed the point. Your turbo makes power off of efficiency. If there is less pressure on the exhaust side of the turbo then it will take less energy to make the turbine wheel spin. The more energy you have to put into spinning the wheel to make up for backpressure after the wheel the less power you will make. No exhaust is the best turbo exhaust.

 

"i don't think anyone has a chart/sheet to compare"
so if no one has a dyno that shows this why is everone wanting a 3in pipe. Its the same as me telling you advil works better for pain then Tylenol but till you test it you dont know.....

 

3" is the magic number for one reason : availability, if 4" was commercially available, then 4" would be what people want.

You need the largest exhaust you can get your little hands on for a turbo car, and you don't need a dyno sheet.

If this was a class named "turbo 101", then consider this your first lesson.

Flow is a function of the pressure drop accross the orifice. Reduce the restriction at the outlet and you increase the pressure differential, therefore increasing the flow..just do it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by love2xlr8integra &raquo;</TD></TR><TR><TD CLASS="quote">"i don't think anyone has a chart/sheet to compare"
so if no one has a dyno that shows this why is everone wanting a 3in pipe. Its the same as me telling you advil works better for pain then Tylenol but till you test it you dont know.....</TD></TR></TABLE>

Assuming that the turbine is an isentropic process, which is really isnt because nothing is 100% efficient, the work that turbine can produce per unit mass is
w = h1 - h2
where w = work per unit mass and h = the enthalpy at each state of the turbine. 1 = before the turbine and 2 = after the turbine. enthalpy is the measure of how much energy a substance has at a given state (certain temperature and pressure) so lets assume Temp remains constant and pressure is the only variable to base enthalpy on. Well the higher the pressure, the higher the enthalpy; the lower the pressure, the lower the enthaply.
There fore the larger the difference in (h1 - h2) the more work the turbine can produce and spin the compressor.
So what we want is a higher pressure on the inlet and a lower pressure on the outlet. we cant really change the inlet pressure, but we can change the outlet pressure by providing less resistance in your exhaust. This can be done by increasing the cross-sectional area of your exhaust and by minimizing the bends and expansions and contractions (from the cat, resonators, etc). Theorectically you make the most power with the largest shortest exhaust.