I'm probably missing where this has been discussed before, but I've heard on numerous occasions that a regular turbo is way worse for your engine (particularly rotaries) than a centrifugal blower. I plan on getting a blower and putting a modest 7psi boost so i don't strain anything.... but I was curious to have more rotary knowledge help me decide how this could be a bad thing.

Also makes me wonder why everyeone doesn't get a blower.

 

A centrifugal supercharger is not a blower. It would be difficult to make a blower work on an RX-8. Regular turbos and regular superchargers are worse for an engine. Increasing HP is always bad for the life of the motor. Everyone doesn't get a blower because A. there is not one available. B. not everyone wants a blower

A blower is a supercharger that sits on the intake manifold and blows air directly into the motor.

 

Any forced induction whether it's a turbocharger, supercharger, or nitrous is "bad" for your engine because it increases stress. Even "modest" boost of 7 psi is bad to some extent. A turbo is probably better performance-wise because of the increased exhaust backpressure at low RPMs plus the fact that the rotary's high RPMs spool the turbo faster than most piston engines. I also don't think the Renesis really has the torque to spare for a supercharger's parasitic power loss so why not use the waste/exhaust energy?

 

Ok.. a centrifugal blower (as I was told) was a turbine that was belt driven. And yes, I was under the impression it went directly into intake manifold...but it's blowing cool air. So, I would assume that I'm not going to hurt my engine too badly. Also, the friend that's been telling me about a blower said if they don't already fit one to the rx8, then they'll probably have one out in not too terribly long anyway. He said that they were very multi-applicational as far as fitting on different cars.

And, if you're right, and there is no healthy way to do a mega-power boost for my car, then what sort of decrease in engine life are we talking about? (again, sorry if i'm posting under a less appropriate thread)

And I didn't want to run hot air through my car...that's why I didn't want to use the typical turbo.

 

any time you compress air, it's going to get hotter.

 

So you're point is that there is no difference worth worrying about? Or is there?

 

I can't decide whether I'm going to ever get crazy enough to risk spending 3-5k on a turbo that's just going to probably hurt my car. *sighs* Perhaps I'll just stick to weight reduction and a new REVi and exhaust. Afterall, I only have 3k miles...no mods yet.

I need a hug....

 

You can't avoid the heat.
Intercooler helps some but it's still going to run hotter.
How long will your boosted engine last? Nobody can really say.

Just adding a blower would do nothing for you. Engine/fuel management is the key.

 

Very informative. Thanks for all the info. I'll still be checking this thread if you have any tasty tid-bits or suggestions. I'm completely a newbie in the whole car-mod thing.

I also don't know how engine/fuel management is relevant. : )

 

You need to be able to control the amount of fuel being used. Also, adjusting the timing of how the spark plugs fire may give additional performance improvements but that's secondary to the fuel. Like Ajax said, the forced induction (FI) will run hotter. The laws governing gases show that if you compress the gas (like with a turbo) it heats up with the added energy. An intercooler helps cool the compressed gas back down a little. But the engine also needs to run a little richer, or in other words with more gas. Not all of that gas is being burnt but that's ok because the additional gas helps by acting as a kind of coolant, carrying away heat. If you run with too little gas being burnt, or "lean" as it's called, then the heat starts doing bad things to your engine.

I picked most of this up by studying the posts of MazdaManiac and RotaryGod. They seem to be up on the technical problems of this sort.

 

How do I regulate the amount of fuel going into my engine...how do I make SURE I don't have to little running through? Go buy a performance fuel pump or something?

 

First of all a "blower" is a supercharger. A turbo is a supercharger. It doesn't mater if it is exhaust dricven or belt driven. I assum what your freind means is a roots supercharger. These are misconceved to be blowers, but that is incorrect. The term "blower" is slang anyway for supercharging. The fact is if I wanted to get technichal that a roots is not a blower at all, nor a compressor, it is a pump.

Next know that the "wasted exhaust" that you use is not free. Why then would you spend money for a free flowing exhaust? A turbo is a plug in the exhaust.
You talk about adding back pressuure like it's a good thing.

As far as the centrifugal blowers go all turbos are of that type. However for this application it is universally considered the worst choice when belt driven.
The roots is the worst efficiency wise and is bulky so this leaves us with two rather less know types of compressors to optimize the rotary. One being the screw blower and the other one is the unit I build the axial flow.

Use your search button to find lots of info on both these units. Hymee in Australia is developing the screw kit for the 8 and I the axial. There might be other kits being developed using othe type compression but I'm not familure with those.

Turbo kits are rumored to be coming out every day but the only one really available is the Greddy.

 

weight reduction is good but that revi will only take you so far....

 

Wow, you are a newbee. Better use the search again it's all in here, in great detail. There is no current answer to your question, lots of minds are working on it. If it were simple as a fuel pump I'd be selling "Dukes" (an aircraft pump) pumps like crazy.

 

hehe use the search button..you'll get a whoel lot of reading..but look at the bright side..by the time you are done with it all....you'll have a lot more knowledge..and one of the supercharger kits might acctually be out for you to buy :D. (the latter might be wishfull thinking.......)

 

Centrifugal superchargers suck *** - they only make power as your RPMs climb

If you're getting a supercharger and you're going to suffer the parasitic loss, go with a roots type - this has max boost at all times, so your torque curve is just nasty.

 

what thread can i find the Turbo VS Supercharger argument? I'm not asking for a response here just a pointer to where I can find it. I've been looking all over for a thread that satisfies my curiosity about the two. I'm wondering why folks are weirded out over a "parasitic" supercharger if it MAKES power... in other words, don't know where the power loss puts a strain..or how it's any different than the strain a turbo puts on an engine. Anyone know where this thread could be? LINK ME!!!

Thanx again.

 

here are soem threads that talk about it.....there are a lot of others that have it too...but they start off on a different topic but sway into the turbo vs supercharger discussion. you can also check out the threads that rotary god made about boosting the 13b-msp (he made one abotu how the auto has less power potential)..they are good and insightful reading...you'll learn a lot. also richard paul is good reading. as are a bunch of others those are the tow that are right at the top of my head :D

https://www.rx8club.com/showthread.p...o+supercharger

https://www.rx8club.com/showthread.p...o+supercharger

 

i didn't read through those threads but i think one of them talks abotu your parasitic loss question..haha but don't quote me they are a few pages long :p

 

thank ye thank ye

 

i've been looking at FI options of teh 8 for a long time..i stumbled on this sight looking at compressor maps for garrett turbo's...here is a free tech article they have.

http://www.turbocalculator.com/turbo...ercharger.html

 

rock on. you rule for that. that'll truly feed my ignorant brain cool stuff about forced air things. no really. ;P

 

look - you'll make more power with a turbo and if we're talking GReddy turbo v centrifugal supercharger, you'll make full boost faster with the turbo as well.

 

But don't the belt driven superchargers avoid turbo lag?

 

Yes but if you have a centrifugal supercharger that makes boost pressure as the square of the rising rpm, you hardly have any boost down low. If you have a centrifugal supercharger that makes 8 psi boost at 9000 rpm, it only making about 4 psi at 5000 rpm. Below about 3000 rpm you are probably losing power due to the losses associated with them. If a turbo (any turbo) lags for a split second but then recovers to full boost, lets say 8 psi, and it hit this number by 3000 rpm, who's faster? Most boost throughout the powerband makes more usable power where you need it.