FI Decision Thread
03-12-2010, 11:19 PM
#46
I want the best kit for a daily driver and longevity for the best price. Stillen has showed a lot of R&D where as GTM has not posted as much.
Stillen / GTM both get +1 for looks (my opinion)
GTM gets +1 for price
Stillen gets +1 for R&D
which means for me they are a tie and now it will be the price of install. GTM says 12-14 hours and stillen says 10-12 hours. Which means stillen my cost less for labor over GTM which may make the final cost of each kit the same
Stillen / GTM both get +1 for looks (my opinion)
GTM gets +1 for price
Stillen gets +1 for R&D
which means for me they are a tie and now it will be the price of install. GTM says 12-14 hours and stillen says 10-12 hours. Which means stillen my cost less for labor over GTM which may make the final cost of each kit the same
Sam doesn't have two marketing guys to sit around post updates and chit-chatting on the forums. He's been quite busy tuning a G37 and a 370Z and developing the stage 2 and stage 3 kits for both.
03-13-2010, 12:09 AM
#47
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honestly the only way to really test them all is numerous installs and time. all the hype and marketing just gets in the way and confuses people. gtm, stillen and greddy all have negatives against their kits and customer service so no point really considering that.
for anyone who is seriously interested in f/i, you should sit down with the person who will install and tune it. they will be the 1 who can sort all the actual cost of going f/i. take whatever you think it will cost and add 50-100% of the cost to be safe. going f/i on a car built for n/a isnt always easy but it can be done well if you plan it out.
for anyone who is seriously interested in f/i, you should sit down with the person who will install and tune it. they will be the 1 who can sort all the actual cost of going f/i. take whatever you think it will cost and add 50-100% of the cost to be safe. going f/i on a car built for n/a isnt always easy but it can be done well if you plan it out.
03-13-2010, 12:24 AM
#49
Registered User
honestly the only way to really test them all is numerous installs and time. all the hype and marketing just gets in the way and confuses people. gtm, stillen and greddy all have negatives against their kits and customer service so no point really considering that.
for anyone who is seriously interested in f/i, you should sit down with the person who will install and tune it. they will be the 1 who can sort all the actual cost of going f/i. take whatever you think it will cost and add 50-100% of the cost to be safe. going f/i on a car built for n/a isnt always easy but it can be done well if you plan it out.
for anyone who is seriously interested in f/i, you should sit down with the person who will install and tune it. they will be the 1 who can sort all the actual cost of going f/i. take whatever you think it will cost and add 50-100% of the cost to be safe. going f/i on a car built for n/a isnt always easy but it can be done well if you plan it out.
03-13-2010, 01:44 AM
#53
I think another factor that you should consider when choosing between superchargers and turbos is power-robbing characteristic of superchargers. Why does it take 8-9 psi for a supercharged engine to make the same power that only takes 6 psi to make for turboed engines? Because a portion of the horsepower is powering the supercharger blower, instead of going to the wheels. So if you look at the big picture, even though a turboed car and a supercharged car is making the same amount of wheel horsepower, the supercharged engine has to produce 5-10% more power at the crank. So a supercharged engine is having to work harder to produce the same power. This will put more stress on the rods and pistons. Just my 2 cents.
Last edited by Modme; 03-13-2010 at 02:01 AM.
03-13-2010, 02:16 AM
#54
That's true and that is one of the draw backs of a SC. But one thing good about a SC is that it helps the bottom end. More power quicker. Who drives around at 5-7000 RPM where a turbo is most affective. The car already has pretty good top end, but lousy bottom. That is what I think we are trying to fix.
03-13-2010, 02:31 AM
#56
Good read:
Engine Horsepower vs. Wheel Horsepower
The Real Story of Parasitic Supercharger Power Loss
The question is frequently asked, "How much boost is safe to run on a stock engine?" This is an important question that requires more than a simple answer of how many pounds of boost. Most people think of boost rather than of horsepower. The question really should be, "How much horsepower can I run without damaging the engine?" Because of the efficiency differences from system to system as well as many other factors involved, the boost can almost be an irrelevant part of the equation. Obviously, the more boost pressure you have to stick into the engine to receive the desired horsepower output, the harder that is on the engine itself. The optimal goal is to achieve the most horsepower output with the least amount of pressure in the cylinders.
When we talk about horsepower output, there is another large factor that needs to be considered - the difference between actual engine horsepower and wheel horsepower. What is important to the driver of the vehicle is the wheel horsepower (as measured on a chassis dyno) because that is what actually gets your car down the road. Things like drive-train loss and other 'wasted' or 'lost' horsepower are removed, leaving you with only the resultant power to the ground - which is really the only thing that counts for the cars actual performance.
On the other hand, what is important to the engine is the amount of work it has to do in order to produce the desired wheel horsepower. This actual engine horsepower can even be broken down farther. You have the flywheel or crank horsepower (as it would be measured on an engine dyno) and you have the 'real' or actual engine horsepower that the engine is required to produce (which can be calculated by the fuel consumption). This is the actual power demand, forces, and 'stress' that are placed on the internal engine components (rods, pistons, crankshaft, head gaskets, etc.) that when exceeded, cause engine failures.
So the optimal goal is to get the most wheel horsepower (actual performance) with the highest degree of efficiency so that the strain on the engine stays below the failure point. Choosing the power adder that produces the most horsepower with the least amount of parasitic loss is the way to achieve the highest wheel horsepower with the least amount of boost pressure required. This is where the efficiency of the turbocharger truly shines. With almost no parasitic loss, the turbocharger is able to let nearly 100% of the engine's power get to the wheels.
On the other hand, superchargers require that some of the engine's power be used to drive the supercharger. Depending on design and boost levels, this draw can be as much as several hundred horsepower in high boost applications. Even in a lower boost street application, a highly efficient supercharger system may still draw 50-75 horsepower. The net result is that you will have to run 2-4 more pounds of boost pressure and tax the engine with the added stress of an extra 50-75 actual horsepower, as well as supply the extra fuel to feed that 'wasted' horsepower. In recent independent third party testing of two supercharged vehicles and two turbocharged vehicles, superchargers had to run 2 to 4 more pounds of boost and still did not reach the power output of the two turbocharged vehicles.
Engine Horsepower vs. Wheel Horsepower
The Real Story of Parasitic Supercharger Power Loss
The question is frequently asked, "How much boost is safe to run on a stock engine?" This is an important question that requires more than a simple answer of how many pounds of boost. Most people think of boost rather than of horsepower. The question really should be, "How much horsepower can I run without damaging the engine?" Because of the efficiency differences from system to system as well as many other factors involved, the boost can almost be an irrelevant part of the equation. Obviously, the more boost pressure you have to stick into the engine to receive the desired horsepower output, the harder that is on the engine itself. The optimal goal is to achieve the most horsepower output with the least amount of pressure in the cylinders.
When we talk about horsepower output, there is another large factor that needs to be considered - the difference between actual engine horsepower and wheel horsepower. What is important to the driver of the vehicle is the wheel horsepower (as measured on a chassis dyno) because that is what actually gets your car down the road. Things like drive-train loss and other 'wasted' or 'lost' horsepower are removed, leaving you with only the resultant power to the ground - which is really the only thing that counts for the cars actual performance.
On the other hand, what is important to the engine is the amount of work it has to do in order to produce the desired wheel horsepower. This actual engine horsepower can even be broken down farther. You have the flywheel or crank horsepower (as it would be measured on an engine dyno) and you have the 'real' or actual engine horsepower that the engine is required to produce (which can be calculated by the fuel consumption). This is the actual power demand, forces, and 'stress' that are placed on the internal engine components (rods, pistons, crankshaft, head gaskets, etc.) that when exceeded, cause engine failures.
So the optimal goal is to get the most wheel horsepower (actual performance) with the highest degree of efficiency so that the strain on the engine stays below the failure point. Choosing the power adder that produces the most horsepower with the least amount of parasitic loss is the way to achieve the highest wheel horsepower with the least amount of boost pressure required. This is where the efficiency of the turbocharger truly shines. With almost no parasitic loss, the turbocharger is able to let nearly 100% of the engine's power get to the wheels.
On the other hand, superchargers require that some of the engine's power be used to drive the supercharger. Depending on design and boost levels, this draw can be as much as several hundred horsepower in high boost applications. Even in a lower boost street application, a highly efficient supercharger system may still draw 50-75 horsepower. The net result is that you will have to run 2-4 more pounds of boost pressure and tax the engine with the added stress of an extra 50-75 actual horsepower, as well as supply the extra fuel to feed that 'wasted' horsepower. In recent independent third party testing of two supercharged vehicles and two turbocharged vehicles, superchargers had to run 2 to 4 more pounds of boost and still did not reach the power output of the two turbocharged vehicles.
03-13-2010, 02:40 AM
#57
Good read and I see your point. I was aware that turbos could spool quickly but from my understanding, one of the drawbacks from that is that it tops out on the output a bit sooner. So you don't continue to add boost with RPM's, but it just levels off sooner. Am I wrong in this case?
And if that is the case then why are SC any good at all? Just wondering?
And if that is the case then why are SC any good at all? Just wondering?
03-13-2010, 03:13 AM
#58
Hmmmm, I must hang around in a different world than most (it's my own world and I rule). In my world, the roots style superchargers are the ones that provide instant power down low. Centrifugal superchargers were good for high hp at high rpm. Turbos, if sized correctly, could give you high hp and decent power throughout the rpm range (though not as instant or strong down low as the roots). Turbos and centrifugal superchargers are very similar in design just driven differently. My choice of forced induction would be a roots or screw type supercharger for a daily driver hands down. My world might be different though.
03-13-2010, 08:10 AM
#60
Hmmmm, I must hang around in a different world than most (it's my own world and I rule). In my world, the roots style superchargers are the ones that provide instant power down low. Centrifugal superchargers were good for high hp at high rpm. Turbos, if sized correctly, could give you high hp and decent power throughout the rpm range (though not as instant or strong down low as the roots). Turbos and centrifugal superchargers are very similar in design just driven differently. My choice of forced induction would be a roots or screw type supercharger for a daily driver hands down. My world might be different though.