I tried to do a search on this but didnt find much, if there is already a thread please let me know. I would like to know other peoples opinions on weather or not one is "better" that the other when it comes to our beloved Renisis. Also i thought it would be a good POLL to do on "What FI are YOU waiting for" and posting reasons why.( not sure how to post a poll) :o

 

The Turbo Vs supercharger debate goes on in every car forum. There is no better or worse as both will do fine depending on application and intended use. If you gain an understanding of how each system works, you will also be able to see the inherent advantages/disadvantages of both.

For general street and maybe track use, a PROPERLY sized turbo usually offers benefits of both systems: low end torque and increased power at higher RPM. The key being that the turbo has been sized properly to work with the motor i.e. not running out of breath at 6000 rpm or starts to build boost at 6000 rpm.

Personaly, I would love for MazdaSpeed to come out with either system accompanied by the proper fuel enrichment/tuning package. Have that installed by Mazda too and you can look forward to a few years of warranteed fun.

 

While there is only one basic type of turbo that everyone uses, albiet with minor alterations, i.e. ball bearings instead of thrust bearings, there are many types of superchargers, centrifigal, roots, twin screw, axial flow.... Each one behaves very differently and offers certain advantages and disadvantages. For instance a roots is a positive displacement and gives its rated boost all the time, but it is only around 40% efficient, so your not going to be adding serious top end power with it. A centrifugal generates boost as a function of rpm. I believe its approximately proportional to the square of the rpm. So you get max boost only at redline, but they are very efficient, about 70% so great for top end power. I definitly wouldn't recommend picking either a SC or turbo, just based on its type, keep your options open and just pick the best kit available at the time, whatever that might be.

Personally I would just go with whichever kit offers the best quality, price, fuel management system (<-most important as seen by Greddy owners) and consider the company manufacturing it. You'll get great gains with any form of FI.

 

I think Hymee's SC is a twin screw? What kind of efficency does that offer, and how does the boost react to RPM? The reason i ask is i'm leaning toward his. Also considering RP's Axial SC.
Wouldn't it be easier to cool SC air than a turbo's air due to the fact the turbo is driven by hot exhaust?
Sorry if this questions are stupid...I'm a newbie when it comes to FI. :o

 

One advantage of turbo: its available RIGHT NOW! haha :D

 

Actually, the Greddy kit is a "Good" kit at a Great price. The E-manage is the downfall. however that will not always be the case, with the new ecu's comin out.

 

A lot of the twin screws (due to today's modern design & less leakage) are getting into the high 60 percentage range for efficiency. With twin screw it is similar to roots, where you get hp & tq right off idle. Downside of these design is they start to wheez out on the top end, build cylinder (in our case rotary) pressure when it is at a high point (tq peak) so it puts more strain on the engine. Also, since power comes right off idle, you may not have enough traction off the line.

Some of the Roots/Screw SC designs have the intercoolers (Stllen, Blitz, etc) others do not. The notion by some that these designs don't need air cooling is ridiculous. Heat not only comes from the temperature of the incoming air, but much of it occurs during the compression of the air in the SC/TC.

 

^ I cant imagine NOT having enough traction to get off the line...that would be GREAT!!! Have you heard anything about how the Axial Flow reacts?

 

Not anything more than what we have read on the board. Richard posts here regularly, so maybe he might be able to chime in.

 

According to Richard, his unit will perform just as well without and intercooler IIRC

 

http://en.wikipedia.org/wiki/Supercharger
http://en.wikipedia.org/wiki/Turbocharger

http://auto.howstuffworks.com/turbo.htm
http://auto.howstuffworks.com/question122.htm

Some great articles.

 

Thanks Photic, those are very informative. Now the problem i have is the more i learn about each FI setup, the more i cant deceide on which one to get...when available. I dont plan on getting FI till late next year and hopefully alot of these kits will be available then. Till then i'll keep researching this stuff!

 

Look at a few different systems and try and see which offers what you want. I.E. how much power/price/installation difficulty/reputation of the company/how far away a mechanic who can fix these things is. And other things of that nature, and I'm confident you'll find which one is right for you.
Personally I'm waiting on Richard's axial flow unit, it looks very nice for my needs and seems like it will be fairly affordable.

 

One of the things i like best about Richard's SC is the basic fact its an Axial flow. That is a unique feature, it would be kinda cool to have not only a unique engine but also a unique supercharger!
I know that is not a practical reason but if it does turn out to be a quality unit, the uniqueness will help! I wish he would provide more updates but i guess he is a very busy guy...understandable!
One question i have is does a supercharger also require a BOV? I asked this question to a couple people at the rotary rally but didnt get a real answer.