Evil Aviator

I wasn't arguing semantics, but rather trying to point out that a supercharger doesn't create the instant boost like you hear in the hotrod rumors. When the supercharger is below its boost threashold (yes, they have one), there will be a lag time before boost sets in, just like a turbocharger. Yes, you are correct, there will be near zero lag once the supercharger passes this boost threashold line. However, there will be some additional lag with the supercharger depending on the effectiveness of the clutch or bypass valve. Also as a non-lag related sidenote, most Roots and Lysholm-type superchargers will not create max boost until about 3,000-3,500 rpm (depending on the setup), which is about where a turbocharger of the same boost level would also create max boost.

... as well as better throttle response, less weight (and less space in some cases) than a turbocharger system, you don't have to mess with your exhaust system, and I still maintain that it looks and sounds unique (Evil intangibles).

The TII is still your best bang for the buck, as well as the best bang for your time and effort, and I will continue to maintain that statement until the market makes a drastic change in TII pricing or forced induction pricing and/or technology. I'm not going to forego science and economics just to make someone feel better, and I don't think that RETed or any other knowledgeable person on this forum will, either. Granted, sometimes it is fun to do something that doesn't make much sense, just to see how it works, or maybe just to be different or make a statement. There are not any forum rules that say you need to listen to any of the posts here, so please just lighten up a little.

I realize that debates sometimes make for some tension on this forum, but you will find that the other automotive forums lack this tension because they also lack any knowledgeable members. Just look at one of the other forums sometime, and you will notice threads with a whole lot of posts of "hey, does anybody know...", answered with "I don't know, but", or "that sounds cool", or "I was wondering that, too", and various other worthless replies. You may have noticed the same thing when talking about your car with your friends and family who also don't know what you are talking about. Hehehe, "Hey mom, I'm going to put a 4-rotor nitromethane engine in my car" - "oh, how nice dear, will you be home in time for supper?". You can't have a debate unless you have a clue. I guess that sometimes it is fun to run your crazy ideas past people who lack the knowledge to debate them, but I still prefer this forum most of the time.

BTW, I still think that trying to make an NA into a TII is a stupid idea in most cases.

RETed

Some people are just stubborn - I get tired banging my head against stubborn heads.&nbsp I'm trying to offer the most practical option for most people; I realize that not all of you care to listen - that's fine with me.&nbsp What does irritate the **** out of me is the amount of BS this thread has uncovered - if you read through all the misconceptions, you'll see the stubborness that pops up no matter what kinda of proof opposite you throw at them.&nbsp I put that Excel graph to prove a point, but a lot of you people are in denial - fine with me.&nbsp I'm not going to get into a huff, because you don't listen.

You can make all the excuses you want.&nbsp Stock ECU or not, I ran my dyno runs on a Autothority ECU which made the car run like crap.&nbsp I'm surprised the Horiba Lambda showed the AFR's as being spot on - the RPM ranges above 3,000RPM was all set to "0", so it's overly retarded timing on the reprogrammed ECU, obviously.&nbsp Like I said before, this can easily escalate into a "well, I could've done this" debate, which you have proved true...

The SC NA is not an option for everyone.&nbsp It's the same are your argument for turbo'ing is not an option for everyone.

What I base my opinion on the SC being not a viable option is this...
1) The Nelson kit is MINIMUM $4,000.&nbsp Someone threw a $3,000 price tag, but I don't think most people can get this price?
2) A good, used Turbo II can be easily had for that price.&nbsp I know people will complain they can't find a good, used vehicle - well, I can't control demographics.&nbsp You gotta be patient sometimes; it took me 3 YEARS to find may AE86.&nbsp During that time, I've scoured Autotrader, Cars.COM, Yahoo Cars, ebay, and Excite Classifieds almost religiously.&nbsp I've finally got mine for a sweet $1,400 (out the door) deal that I can turn around and sell for $3,000 right now for a 100% profit due to it being a hatchback.&nbsp Was it easy?&nbsp No.&nbsp Did it take time?&nbsp I think so.&nbsp Within that same time, I've had friends who have picked up FOUR Turbo II's that are under $1,000 each (average about $500 each).&nbsp Granted 3 out of the 4 were either engine fires or blown motors, but sub $1,000 J-spec motors easily fixed that; we're lucky we have the knowledge and the know-how to fix these major problems.&nbsp They 4th car was a $700 PRISTINE silver '87 Turbo II that had 130k miles on the OD - the car was super straight and super nice paint for almost a 15 year old car!&nbsp The cars are out there - you just gotta be patient.

Add a full exhaust (3" custom from the local muffler shop should be about $500), and the appropriate fuel mods, and you have a reliable 13-second car.&nbsp Turbo lag?&nbsp I don't feel it has any significant turbo lag - sure a SC NA might give you a little better throttle response.&nbsp In the long run, the beefier Turbo II drivetrain will prove to be more reliable than a high-strung NA that's SC'd; care to argue otherwise?&nbsp I bet the majority of these folks who are stubborn against a Turbo II have never driven one...can we get direct experience here?

(Hoping to stop adding to this ridiculous thread...)


-Ted

N1XRR

Blah blah blah

Man, some people need to reseach SC's more.

Roots type is nice because it gives you x amount of boost almost all the time. Centrfugal is nice because the faster it turns, the more boost it produces.

SC's are REALLY nice(espically roots type) in auto-x. That linear power is whats really best, and the fact thats its on ALL the time.

And as I've learned, spouting off numbers from even identical dyno's(event he same dyno) may be off +/- 10 hp. Why? It depends how tight they strap down your car. I've seen my car go from 185 to 197rwhp by just tightening up the straps. Nope, I will never trust dyno's to be 'true' tests of HP again.

Michael

Aaron Cake

iTrader: (1)

Hey!

RETed

If you wanna get technically about it, the last time I checked ALL "superchargers" (including turbochargers) do this.&nbsp I think you meant the linear response between RPM and boost; if this is the case ALL superchagers do this, including roots types - it sounded like you were implying the roots type didn't.


Last time I checked, an SC on an FC NA turned it into an instant E Prod vehicle.&nbsp Last time I checked, ANY FC in EP was not competitive.


Now this is an interesting comment.&nbsp This basically implies that would never trust ANY dyno.&nbsp So how to do you compare power numbers?&nbsp I've NEVER heard this happening on "low powered" vehicles on a DynoJet unit.&nbsp This would not suprise me on those double roller "Mustang" and "Clayton" dynos though.&nbsp How about an eddy current DynoPack dyno?&nbsp SCC mag compared the DynoPack to the DynoJet, and the numbers were basically identical.&nbsp Your comments are a pretty stupid thing to say - you basically throw out all modern methods to measure power output from vehicles out the door, which makes this whole thread a waste of time?



-Ted

FPrep2ndGenRX7

quote:
--------------------------------------------------------------------------------
SC's are REALLY nice(espically roots type) in auto-x. That linear power is whats really best, and the fact thats its on ALL the time.
--------------------------------------------------------------------------------

Reted said:
Last time I checked, an SC on an FC NA turned it into an instant E Prod vehicle. Last time I checked, ANY FC in EP was not competitive.



I get to correct Reted! I think he meant to say E Mod.

RETed

Doh!&nbsp You're right!&nbsp That's E Modified!
I'm still on vacation in Hawaii!



-Ted

jarrod

how about a blown,nitromethane burning
top fuel fc....
would love to see a 6-71 or 8-71
on nitro piped up to a 13b..LOL

that would be a site to see....LOL

slinges

Has anyone considered a G60 supercharger from a VW Corrado? These can be picked up for less than $500 and it seems like all you'd need is the custom mounts which you'd need for any type of SC. What about some SC's from some other production cars...Thunderbird SC, Grand Prix GTP....any thoughts? Seems like if you CAN run the stock ECU, a supercharger is a much less expensive option than a turbo, especially for somone with n/a car that they're quite attached to (like me). It also seems like a supercharger would be a LOT easier to hook up than a turbo, because of all the custom work involved. I would probably use a small FMIC with a supercharger anyway, because of the limited amount of boost available with the charger (I think a G60 would only make about 8psi with the correct size pulley for an 8000rpm redline). Any comments on this?

ShaunB

Im going to get a 7 inch camden supercharger from atkins rotary, and going to be running a 90 turbo 2 motor with the turbo 2 tranny, and when i get it done i would gladly show you a dyno, then you could see the difference between the SC and the Turbo, and im not talking about the HP numbers, im refering to the power band.

Funklord

a turbo can run higher boost with a smaller unit. its also more efficient.. you get **** HP per PSI, because the faster you turn an SC, the more power its belt saps from your engine. a turbo gets power from something you dont need anyway.. your hot exhaust. if things were perfect engines would make 100% mechanical energy that make syour engine go and 0% thermal energy which does nothing for you. but since they arent the best we can do is take the excess thermal energy and put it to good use. plus, superchargers screech like somene dragging their fingernails across a blackboard, whereas a turbo wails like a jet engine. personally i think a turbo is more streetable, because when you're just driving around doing errands, you dont use the turbo, which means no boost, and you'd use less gas. if you're ever racing your car, you probbably wont be spending a lot of time in the 1-4000 range, so who cares what your low end is like. if you want a car with lots of low end, why did you buy a rotary? on the other hand if you had a v8, a SC would probbably be a better idea, because you woudlnt need a crazy wicky wack manifold, and v8's dont usually run really high boost anyway. also a big v8 probbly spends a lot less time in really high rpms, if at all. so a supercharger would be much more effective. but you dont have a v8, you have a rotary, so get a damn turbo!

thats my story

ShaunB

I have had 2, 87 turbos, and a 89 turbo. and i have also rode with my brother in his 1 gen, 4 port with a 5 inch supercharger. And I would have to say the supercharger pulled alot harder all the way to 7000 rpm. i have also race him in a 87 turbo he pulled 3 car links on me. there for i know how, both of the supercharger, and the turbo Rx7 runs. Therefore i will be getting a 7 inch supercharger. and you can still change your boost on the superchargers, and in that dyno how much boost was he running i seen 10 psi turbo 14 psi turbo. but nothing for the supercharger. thats my thoughts

RX-7Impreza

you know i dont get all of this "Why do it? it will be more expensive for less power and inefficient." tell me, what better describes the act of purchasing a rotary powered car than the previous statement??

Top 10 reasons to put a SC on a rotary instead of a turbo??

10) because it sounds really really cool.
9) turbos are harder to tune and less predictable
8) because you can then say "I have a SC rotary."
7) because people told you not too
6) because you are making a unique car even more unique
5) they may give you a "SC Rotary" section on the forum
4) It is a challenge to overcome
3) if you wanted cheap, overabundant, easy to come by power. the emblem on the back of your car would be 5.0 and not RX-7.
2) you are an enthusiastic mechanic and that is what you do

and the number one reason to Supercharge your RX-7.......... :drumroll:

1) because you can.



I personally dont care about the cheapest easiest way to make my car fast, because that way comes with 8 cylinders. you have a unique car as it is...... why follow the trend now???

Justin

Rotary-Revolution

Yeah! Right now I tell the local ricers I have a "Rotary" engine and they scratch there heads and say things like "so how many pistons?"

I would love to see what they would do when I add "Supercharged" to that!


But Turbo, Supercharger, or N/A they sill.....
Isnt that the ultimate goal!

Liquid Anarchy

iTrader: (2)

Hehehe, it's being worked on. I believe it's making it's debut in Dallas sometime soon. Can't say much more than "Yes, it exhists. Yes, I've seen it. Yes, I've seen it run. And yes, it's VERY loud." I can't wait for it to go public.

deadRX7Conv

I was dreaming of a S/C kit for the vert. But, the cost is outrageous. If they can sell a kit for $1800 for a 5.0, why can't they make one for $1800 for the rotary?

It can be done. But, why bother spending $4000 on a car that didn't even cost that much.

I also don't want a $2400 roots kit(camden). I want to keep the FI and would prefer an eaton/whipple/screwtype/...over an ol' roots type.

I'll just have to wait until I stumble on a Nelson kit(or a T2) in the salvage yard.

seymour30uk

interesting thread, more info please...

those who have come on with a ' my TC is faster than your SC' attitude, please take it away with you, if you want a faster car than anyone else go buy a skyline or someting. I bought an RX cos it was unique, challenging and different, and would be interested in the Supercharger concept for the same reasons. So if posting, faults or problems, yes. challenges and 'cockfighting', no

lechnoid

i only have a minute to go into this, but there's one issue through this whole thread that nobody has seemed to catch onto (unless i missed it)...

when it comes to fuel issues, increase, decrease, etc...if you'll notice, the atkins SC setup converts from FI back to the good 'ole carb. why? cheaper, with better performance. don't believe me? call dave for yourself and he can give you the full run down. i know their website was posted earlier, feel free to drop him a line.

another thing...boost levels. dave atkins told me over the phone that he has run his daily driver at 15 psi and has had customers push as high as 25 psi.

after months of research, i've finally decided on the route i'm gonna be taking. for around $6K, i'll be pushing my engine to 400 hp. i could go higher for not much more cost, but i don't wanna push too hard.

Evil Aviator

I don't think that anybody is debating the "cool factor" of the supercharger, as it is difficult to argue subjective points. I'm sure that a supercharged RX-7 would be fun to drive, and I may even try such a setup sometime. However, the fact remains that superchargers are not as efficient as turbochargers at this point in time. For many people, this is a fault or problem, and should be pointed out especially since the stock 13BT and 13B-REW make good low-rpm power with their modern turbochargers. To sum it up, if you think that the supercharger is cool, then that's great. If you think that the supercharger will give you more power at the same boost level as the stock or aftermarket turbos, then think again.

LOL, better performance than what? Yes, the carb setup may be better than trying to make the stock ECU work with the forced induction, as is common with many of the ghetto mods found on this forum. However, there is no way that any carb will give better overall performance than a good aftermarket EMS. I think that even Dave would admit that the Microtech EMS that he sells would prove far superior for power, reliability, and drivability, when compared to a carb. If you look on the Atkins site, you will notice that there is a throttle body option for the Camden supercharger - take it!
http://www.atkinsrotary.com/fuelinj.htm

"No one can go fast on a fuel system that is not calibrated correctly, and no fuel system in existence can be calibrated as accurately as a modern electronic fuel injection. For this reason, EFI is the only fuel delivery system discussed in this book" - Corky Bell, "Supercharged!"

Carbs are dead, and the sooner people realize this the better.

BTW, running a SC at 25psi requires the same internal prep and intercooling (if not more) than a turbo. Please don't try to run 25psi in a stock engine.

RETed

Sure, be sure to count every single penny on the project.
In the meantime, I'm helping to build a twin-turbo 13B-REW using twin, non-sequential GT-2535's.&nbsp We'll see whose powerband is flatter...


-Ted

RX-7Impreza

i dont see where the whole "I can get more power with a turbo" thing is coming from. i can get more power with a jet engine, so what. i dont think anyone here will debat the fact that a turbocharger will net more gains than a supercharger running the same psi. i havnt read one person saying that a SC would be better yet the turbo guys seem defensive.

in the end the turbo will kick my SC *** with less money and less time, but i gaurantee that i will appreciate a custom SC setup more than i would a faster turbo setup.

quote me on this... turbos???? been done already. give me a challenge without an instruction manual.

Justin

rxsvn

there are a few supercharged rotaries around where i live (in new zealand, next to australia incase youve never heard of it) but one inparticular is the Mazsport series 5 rx7 that runs a supercharged 20B periphial port. It runs a top ET of 10.4 secs 1/4 mile, which is excellent concidering it is road registered. They didnt say alot about how they combined the supercahrger to the 20b but what they did say was that they had taken all of the 'over laping' of the engine - anyway if you want to talk to them go their site www.maz-sport.com,