With those thoughts in mind, the Centrifugal SC setup should cost less than the Roots SC and TT setups. Especially if the "spool time" is relatively similar on the Centrifugal SC and the TT setups. I would say Roots SCs have a different application (like as close to direct response as possible) as compaired to the other 2 options. I could be off in left field, but that is not how the ball bounces though. I have seen a few Mustang guys get Roots SC systems with everything necessary to make a beast for a few grand. Although their suspension setup sux big time (barring the latest models).

I have stayed away from SCs because I have always run higher revving 4-bangers and I do my best to stay in the sweet spot (in boost) so that I maintain that instant throw-you-back-in-the-seat response. I guess having a 6 cylinder is lilke having a jack of all trades kind of deal.

Kevtex... I have read your posts and for the most part agree with all of them except this one. The power requirement is not the same to get it from a belt as it is from the exhaust. When you take it from the belt you will suffer a larger power requirement due to the parasitic loss etc and you are taking power to make power. Gaining it off of exhaust gasses doesn't cost anything. The engine is shooting out the exhaust gasses whether the turbos are there or not so you are not taking any power from your engine to make the extra power (boost).

^ There is more back pressure with a turbo than without one therefore you are taking some power away. The parasitic losses from a turbo are negligible when compared to the losses from a supercharger though. The SC takes a much much bigger toll on power than the tc.

With a turbo, the engine has to work harder to get the exhaust out because of the increased back pressure the turbo provides. The same amount of extra work is required if you take the power from a crank pulley.

Haha...sorry...I wasn't really asking you were did you find the pic, but rather, where does someone find such a huge safety pin. ;)

I have to disagree with you on that one kev... just my personal stance doing more research right now to provide valid documented points.

Here you go: Why bigger turbos make more HP at the same PSI.... - Page 3 - RX7Club.com

Not at all because the sc has to move gearing and a belt while the tc only has to spin. We aren't arguing for the sake of argument, we know this is and has always been the case. In modern days, parasitic losses from the sc have been greatly reduced through new designs, but its still takes a bigger toll on the engine to make the power.


Also, guys, the whole bigger turbo makes more power thing.... From what I understand its not because it flows more, we know that 5psi is 5psi. What matters is the charge density of that 5psi. According to what Silo posted, a turbo that is in its peak efficiency zone (or island if you've ever seen a turbo flow chart) will create a more dense 5psi than one that is not. Think of it this way... colder air is denser, air particles are more compact therefore there is more oxygen to burn therefore you make more power. The same apparently goes for a turbo operating at peak efficiency vs one that isnt. The one operating at peak eff. somehow produces a more dense charge (at the same temperature) as the one that is out of its efficiency zone.

The post by silo didnt explain why, but I have a feeling it has something to do with how the air is compressed in a more efficiently sized tc than a less efficiently sized one. Efficiency relating to the size of the engine and the amount of psi you are targeting.

I'll do some more research and let you guys know.

And the parasitic loses of a s/c are always way higher then the losses due to backpressure increase by a turbo. Don't forget that otherwise wasted engery (in form of heat) is used to drive the turbo. The overall efficiency of a turbo is higher than that of a s/c which doesnt mean that I would roule out a s/c - I even prefer it since you can reach a certain amount of gain with less cost and less labour and with less parts (less parts = less possible source of trouble).,

Having said that, a birdy told me there will be a press release later today... ;)

O.o

Hope that birdy wasn't kiddin....

Alright so after reading a bit from reputable sources. AKA Garrett from the stuff that Silo showed us.

Bigger turbos make more power per the same psi for two main reasons:

1) Bigger turbo will put less heat into the air and therefore the air is denser. More air = more power

2) The actual CFM of the turbo is meaningless. What matters is how much of that air is actually going into the engine and being used. There are restrictions that keep all the air from getting to the combustion chamber, the main one being backpressure from the exhaust housing of the turbo. The smaller it is the more backpressure, the less air that can flow through the engine, the less air that can flow INTO it in the first place and therefore less power. So bigger exhaust housing means less backpressure, meaning more air in, meaning more power.

The logic seems to be that it doesnt matter if the turbo can flow an infinite cfm, if the engine can't make use of it. The less backpressure, the more the engine can use, the more power it can make.

So how does this all apply to the SC vs TC dilemma?

I would say its the same thing, more flow through the engine means more power. So why do manufacturers recommend sticking with 2.5" piping rather than 3" piping on an SC? Because the sc doesnt flow enough in the first place to cause a 2.5" exhaust to become an obstruction??

That was my point. A larger turbo, and i have to state more specific, at a given psi might be more efficient, which means will it heat the charge less, hence more oxygen in that charge.

One simple factor is that it has to "shovel" less. You have a larger shovel you will dig that whole more efficiently than with a spoon. The other factor might be that the exhaust side is larger and therefore pumping loss is reduced. The larger turbo might still be less efficient at a lower psi but usually we compare the peak operating psi range.

Yes, we know sc's have higher internal parasitic losses than turbo's. The majority of the power drawn from the engine is used to to compress the air, not toovercome parasitic losses.
None of this discussion should have any impact on one's decision to buy a GTM supercharger. I've had a turbo before and would prefer the torque curve provided by a a supercharger for a daily driver.

But if the turbo is sized just right, the midrange torque is really good. I had a turbo kit on my old Toyota Celica, and the response was very quick. That also looks like the case for the TT kits available for the 370, judging from the dynos of those TT systems.

Yeah, once I post why, we are all experts and knew all along, but before then no one could give me a specific answer as to why.:rolleyes:

Ya know what I just realized...There is no easy way out......I just need to pick a HP goal for my car....If the SC can do it then I should get it...If the SC can't do it then I should buy the TT kit...

This makes sense, with my 4 cyl turbo, when we just upgraded theintake and Down Pipe we saw huge gains as more air was flowing in and out. When I chipped the ECU I also went 3 in TBE and with the small turbo on the car I hit full boost @ 2500 rpms and actually had more TQ than HP on the car. I had over 300 TQ and about 260 HP on a 4 cyl FWD car, it was fun to feel all that TQ. Since the turbo does create its own back pressure we could go larger on the exhaust (to a point of no return of course) but I guess NA cars use the exhaust to create the back pressure.

tell me again how discuessing turbo's for the last 3 pages is on topic to this thread?

lol.. I was waiting for you to say something shumby! lol... Thanks for the education though guys... I'm definitely learnin' here. lol

MOds/admin. please move the turbo posts to there owen thread. There is useful info here but all these posts will take away from the point of this thread. (GTM's SC) makes it hard to search and find info in this topic

Because the compressor side of a turbo and a centrifugal supercharger are pretty much the same, unlike a roots-type/twin-screw supercharger. Understanding one will give you a greater understanding of the other.;)

to me the point is simple..... if you are making a small amount of boost(3-5lbs) the stock exhaust and cats can handle the amount that is trying to be pushed out. However, the more boost you make (8-10lbs) the more trouble the stock exhaust has . So by removing the restrictions in the exhaust you will see higher gains with higher boost levels.

I think it's all useful information for vets and noobs. Shoot 70 pages of this thread alone is just filled with us begging GTM for information on the SC kit. They should remove that before moving this useful information.

I think the little birdie may have lied about more information today.

Haha, agreed. Also, complaining about turbo/centrifugal sc info on this thread yet not about the random fat guy pics here makes no sense to me, lol.

That is the same result that I saw when upgrading the intake and exhaust on my S13 Fastback (CA18DET). It seemed as if I was at full boost sooner, but I had no way of really telling for sure. I also installed a Power FC the next day and spent like 2.5 weeks and 5 50 liter fillups (sucked) tuning it (mostly DD efficiency). When I upgraded from the T-2-Small to 2871, all I could say was WOW. And it was a bolt on affair.

The next quote pretty much sums it up, but everyone is entitled to their take on things.

Well put.

Sounds like something that I can agree with, but I have never increased boost pressure in my setups. I have only swapped out turbos for more efficiency for my application and driving habits.:ugh2:

Sounds like something that I can agree with, but I have never increased boost pressure in my setups. I have only swapped out turbos for more efficiency for my application and driving habits.:ugh2:[/QUOTE]

You didnt get the car tuned after swaping the turbo to a bigger one?

Possibly a MAF equipped car.

still a tune would put it in its real effiecency range as all turbos have their own sweet spot. On my stock turbo once it was tuned I gained power of course but I also gain a couple of MPG as it was in its sweet spot.

If I had to take a guess, and yeah thats what I'm doing with this post, I'd say the SC doesn't make enough power to bog down a 2.5" exhaust. The turbo's turbine housing would be causing some back pressure relatively close to the engine so I'd suspect the 3" turbo back exhaust would help elevate the back pressure by creating a lower pressure area aft of the turbines. The low pressure area would help increase the flow over the turbines due to a relatively high pressure zone pre-turbine. I don't think that a 500RWHP TT setup produces more exhaust than a 500RWHP SC setup so the 3" exhaust might just help to lower the pressure pre-turbine by moving those gases over the turbine blades faster and more efficiently.

LOL... the way you guys talk (technical stuff) just blows my freakin mind... If we were in a face to face conversation I would be nodding my head like I understood wtf you were saying.....

UPDATE NOW!

i completely agree im soooo clueless from how much people talk technical here :bowrofl: id completely do the same thing u would do stillenz :bowrofl:

I see what kevtex is saying. Laws of physics will tell you the same amount of energy is used to create say 6lbs of boost whether it be by pulley or exhaust. I totally agree with that, but the energy used by the exhaust while exactly the same as the energy used by the pulley does create different effects on the engines HP/TQ output. I still say using the exhaust pressure is more efficient for the engine to create boost and not have such and adverse effect on the current HP output, but yes, it does exhaust the same amount of energy on an atomic level as with the pulley.

Clarification............
 

You didnt get the car tuned after swaping the turbo to a bigger one?[/QUOTE]

Power FC is what I used. Never dyno'd, but I used FC Datalogit to dial in settings for my injectors and boost control module. Took me a long time to tune it (with help from a friend), but my AFR were safe and that was enough to keep me from blowing up. The thing I found odd was that the boost was set @ 10PSI when I bought the car from the lemon lot. I had no idea until I installed my gauge setup. Once I changed out turbos and installed the power FC, I kept the same boost level. The car was a beast compaired to how I purchased it. This was on a CA18DET equipped S13 Fastback (European model).:tup:

So if you are asking me if I had my car professionally tuned, the answer is no. Would I do it once I turbo the NISMO, hell yeah. Too many electronics and algorythms at work in a Z ECU. The CA was simple, which is why I loved it.

HEY DON'T MAKE FUN OF RANDOM FAT GUY!


:rofl2::roflpuke2:

wow this thread has grown 10 pages in 2 days..... and only 1 post from GTM out of the 10 pages.... you guys need to start a new thread and quit thread jacking this one....:tiphat:

Sam gave us something to talk about.....This is a forum...

any other request? Maybe sam can prepare you one of those pretty drinks with a little umbrella while you wait.


:stirthepot:

I think we have showed a lot of info, pics and shared more then any other company that doing this type of work.Yes the process is slow, and i don't think it can be any faster, just sending the car to carb and going through the proses is a big undertaking. them add all the different a/r housing we offer. all different pulley it is a very time consuming work . but that's what it takes .

Sam