Stealthy's Turbo GSR Build Up Thread
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Yes sir...I'm takin the trip from CTizzle next year. Gonna be in the Built Motorsportswear booth y0qwikxr said:that spool rate is gonna be suh=-lowww
not to threadjack - but whats this talk about Carlisle? I'm like an hour from there..
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there is a car show there next spring? and Mike is gonna be there and a few of us are thinking about going up there to see the hatchie.
i went last year, if im still in ohio come next year i will definatly go. thatll be around the time that i COMPLETE my setup (complete build, 600+hp)Jezek said:.82....wanna battle?
No, seriously...you gotta go to Carlisle next year so we can meet up....maybe even run
jacker.....dont worry bout it
i kinda see what you are saying, but you have any pics? im a visual learnerqwikxr said:
not really as much as you'd think, the price tag on the gt35r is bc of the dual ball bearingqwikxr said:that spool rate is gonna be suh=-lowww
not to threadjack - but whats this talk about Carlisle? I'm like an hour from there..
Turbines are actually a very simple science. The turbine powers the compressor because it is a physical restriction in the exhaust flow. The more it restricts (ie: the smaller the turbine) the faster it spins the shaft... but the more it chokes the engine and robs you of top-end horsepower. The less it restricts (ie: the larger the turbine) the slower it spins the shaft... but the less it chokes the engine and the more top-end horsepower you can make. That's the key to understanding a turbine.
A/R is the area Ratio of
All those open areas between the turbine blades on the aftermarket wheel result in far less turbine backpressure, which paves the way for lots more top-end horsepower... but remember: this aggressive turbine will spin more slowly than a smaller one. The slower shaft speed means the compressor spins more slowly, also. When the compressor speed slows down, your boost output falls off as well. This is why large turbines need large compressors to match!
So now it gets real technical...
Its time to figure out how to match a turbo to your engine, this involves selecting the proper compressor and turbine wheels along with the right combination of housing A/R. A mismatched turbo could not only result is extreme lag, but also wasted potential as a turbo can easily outflow an engine. I.e. bigger is not always better.
The only real calculation that needs to be done is to determine how much air you engine is actually flowing. This depends on a number of things including the RPM, absolute temperature (Rankin, equal to 460 + Fahrenheit temp), absolute manifold pressure (psi, equal to boost pressure plus atmospheric pressure), and lastly the engine volumetric flow or EVF in cfm.
First to calculate EVF use the following equation:
EVF= (engineCID / 1728) * (RPM/2)
Next we’ll use EVF to calculate the amount of air in lb/min the engine is flowing under boost and at temperature using this equation:
N= (P*EVF*29) / (10.73*T)
Where N is the airflow in lb/min, P is the absolute pressure in psi, and T is the absolute ambient temperature in Rankin.
Finally, multiply N by the volumetric efficiency of your engine (VE). This compensates for the fact that upon every cycle of the engine, not all of the old air/fuel mix in the cylinders is forced out the exhaust. Thus there is a difference between the actual airflow through and engine and the predicted airflow. This discrepancy is equated to a VE. There is literally thousands of hours worth of online reading about volumetric efficiencies for just about every production engine. To get the most accurate results from this step I would suggest researching your engine and coming up with the most realistic VE possible as this does have a significant affect on engine flow. If you are just messing around with compressor flow maps and need a value for VE just to experiment with, 85% efficiency is a nice conservative number for most modified turbocharged cars at high rpm (6500-7500). Keep in mind though that on a forced induction setup VE can easily exceed 100% so again it will be very beneficial to research your engine.
Want me to keep going, or have you had enough?
Ok, we're almost through..
With the flow rate you have just calculated, you can look at compressor maps of different turbo chargers to see which ones give you the air flow you need at the pressures and efficiencies that you want to run.
When selecting a turbo, it is important to do the above calculations for a number of different RPM’s and boost pressures because you will not always be at redline under full boost while driving you car. Checking the turbo performance at various engine speeds and pressures will give the overall picture of how well the turbo is sized to your vehicle.
Matching a flow map to your engine flow requirements will allow you to pick the compressor wheel trim for your application. However before you go out and purchase that new turbo, you still have to settle on an exhaust wheel and turbine A/R. The real determining factor in this selection is maintaining compressor wheel speed. Remember the wheel RPM lines on the flow map? Well a properly sized exhaust wheel/housing combination will keep the compressor wheel operating within the maximum and minimum wheel speeds on the map as often as possible. Since different “hot side” combinations can affect your turbo’s performance, (i.e. a little more lag in return for more top end, or quicker spool up at the cost of overall power) the best thing to do is to contact a turbo manufacturer or distributor (www.extremeturbo.com, www.forcedpeformance.com, www.turbochargers.com) and they will be able to tell you the exact effects you can expect from all of the various hot side combos available for your turbo model.
A/R is the area Ratio of
All those open areas between the turbine blades on the aftermarket wheel result in far less turbine backpressure, which paves the way for lots more top-end horsepower... but remember: this aggressive turbine will spin more slowly than a smaller one. The slower shaft speed means the compressor spins more slowly, also. When the compressor speed slows down, your boost output falls off as well. This is why large turbines need large compressors to match!
So now it gets real technical...
Its time to figure out how to match a turbo to your engine, this involves selecting the proper compressor and turbine wheels along with the right combination of housing A/R. A mismatched turbo could not only result is extreme lag, but also wasted potential as a turbo can easily outflow an engine. I.e. bigger is not always better.
The only real calculation that needs to be done is to determine how much air you engine is actually flowing. This depends on a number of things including the RPM, absolute temperature (Rankin, equal to 460 + Fahrenheit temp), absolute manifold pressure (psi, equal to boost pressure plus atmospheric pressure), and lastly the engine volumetric flow or EVF in cfm.
First to calculate EVF use the following equation:
EVF= (engineCID / 1728) * (RPM/2)
Next we’ll use EVF to calculate the amount of air in lb/min the engine is flowing under boost and at temperature using this equation:
N= (P*EVF*29) / (10.73*T)
Where N is the airflow in lb/min, P is the absolute pressure in psi, and T is the absolute ambient temperature in Rankin.
Finally, multiply N by the volumetric efficiency of your engine (VE). This compensates for the fact that upon every cycle of the engine, not all of the old air/fuel mix in the cylinders is forced out the exhaust. Thus there is a difference between the actual airflow through and engine and the predicted airflow. This discrepancy is equated to a VE. There is literally thousands of hours worth of online reading about volumetric efficiencies for just about every production engine. To get the most accurate results from this step I would suggest researching your engine and coming up with the most realistic VE possible as this does have a significant affect on engine flow. If you are just messing around with compressor flow maps and need a value for VE just to experiment with, 85% efficiency is a nice conservative number for most modified turbocharged cars at high rpm (6500-7500). Keep in mind though that on a forced induction setup VE can easily exceed 100% so again it will be very beneficial to research your engine.
Want me to keep going, or have you had enough?
Ok, we're almost through..
With the flow rate you have just calculated, you can look at compressor maps of different turbo chargers to see which ones give you the air flow you need at the pressures and efficiencies that you want to run.
When selecting a turbo, it is important to do the above calculations for a number of different RPM’s and boost pressures because you will not always be at redline under full boost while driving you car. Checking the turbo performance at various engine speeds and pressures will give the overall picture of how well the turbo is sized to your vehicle.
Matching a flow map to your engine flow requirements will allow you to pick the compressor wheel trim for your application. However before you go out and purchase that new turbo, you still have to settle on an exhaust wheel and turbine A/R. The real determining factor in this selection is maintaining compressor wheel speed. Remember the wheel RPM lines on the flow map? Well a properly sized exhaust wheel/housing combination will keep the compressor wheel operating within the maximum and minimum wheel speeds on the map as often as possible. Since different “hot side” combinations can affect your turbo’s performance, (i.e. a little more lag in return for more top end, or quicker spool up at the cost of overall power) the best thing to do is to contact a turbo manufacturer or distributor (www.extremeturbo.com, www.forcedpeformance.com, www.turbochargers.com) and they will be able to tell you the exact effects you can expect from all of the various hot side combos available for your turbo model.
btw i have the following on order
cp 9:1 81.5mm pistons to replace the je 9:1 81mm pistons
arp head studs
honda bearings
new water pump
new itr oil pump
new timing belt
new headgasket
it will also get micropolished crank during the machine work phase before assembly
btw, this was financially feasable compliments of the guy who wrote me a $900 check to get my bumper fixed (that im putting off til i get the whole car painted) , so that helped
cp 9:1 81.5mm pistons to replace the je 9:1 81mm pistons
arp head studs
honda bearings
new water pump
new itr oil pump
new timing belt
new headgasket
it will also get micropolished crank during the machine work phase before assembly
btw, this was financially feasable compliments of the guy who wrote me a $900 check to get my bumper fixed (that im putting off til i get the whole car painted
) , so that helpedMr. Jollypants
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Beer bong FTMFW!
Nice turbo though, oh, and nice rod.
Nice turbo though, oh, and nice rod.