What's wrong with superchargers?
 

Such as the MP62? Is it that they are somewhat limited in boost? What about the cold side supercharger setups?

Does this look like something you'd want in your car?
Attachment 239930

Cuz they whine like a bitch and i already have enough bitches whining in my car.

I ran a ffs cold side setup for about 3 years. the major issue is the heat, both heat soaking the blower and heating the air. I ran water injection, both pre and post blower, and never had a problem. I was running 13psi, 225-230rwhp, and the car was predominately used for track days. before I took it apart to go V8, it was one of the fastest track miatas in texas. If you are looking for a FFS kit for a 99-00 let me know, because I've been meaning to post mine up for sale.

A man walks up to a young woman in a bar and says "I can tell that you're going to get laid tonight."

"And how do you know that?" the woman asks, "Are you psychic?"

"No, I'm just stronger than you."



It's not so much that we hate positive-displacement superchargers, we just hate the people who use them. There are two principle and vastly different reasons for this.

First, the Miata aftermarket is at present principally supplied with supercharger systems by two specific vendors who have historically tended to make false and misleading statements about the kits that they sell. This has tended not even to involve the superchargers themselves, but rather the brain-damaged engine management solutions which they have packaged along with them.

Second, there's virtually no reason why one would actually be justified in installing a positive-displacement supercharger as opposed to a turbocharger. All else being equal, positive-displacement superchargers tend to be more expensive, less efficient, hotter running and make less power than a comparable turbo system.


In considering these facts, one can then look with considerable opprobrium at the extremely vocal minority of Miata owners who blindly espouse with near religious fervor the virtues not only of positive-displacement superchargers in general, but of the lying jackasses mentioned in point #1 in particular.





And here is a picture of a cat:

https://www.miataturbo.net/attachmen...ine=1339895892

200 ft-lbs of torque at 2500 RPM is pretty slick, in my opinion.

https://www.miataturbo.net/attachmen...ine=1339896096

But then, this is not the typical MP62 setup.

I think it depends on the intended use of the car. If I were doing ANYTHING with my car other than Autocrossing it I would have a turbo on it.

And what the ---- do u want 200ft-lb of torque at 2500rpm for? You plan on shifting to a 4k redline or something? Reality is when you're racing you're not going to see that "epic torque" at 2k or 3k or even 4k.

Oh, I'm sorry, did the OP specify that he was interested in racing application only?

You use that 200ft-lb torque on every light so u can shift at 4k rpm?

Are you trying to construct an argument that less torque (or less area under the curve, if you prefer) is desirable? I didn't say 200 ft-lbs at 2500 rpm is the end-all be-all. I said it's "pretty slick." It's nifty. Neat. Fun. Enjoyable.

https://www.miataturbo.net/attachmen...ine=1339898385

... And that's what's wrong.

Im pretty sure the point is that theres simply no point in having the torque there, when you can have shitloads more 500rpm later turbocharged.

I mean, why is 200tq at 2500rpm better than 250tq at 3000rpm?

Dann

Why not 300 ft-lbs at 3500 rpm? Or 350 ft-lbs at 4000 rpm?

I swear, I completely agree with the overall (and dramatic) superiority of the turbocharger in almost all applications. But it's silly sometimes the lengths people go to argue this point...suggesting that lots of torque way down at 2500 rpm is somehow bad.

Really?



As for why I want to shift at 4k, I think I have a completely legitimate reason. After 4k, the Whipplecharger's volume is migraine-inducing.

I wasnt arguing anything i guess this speaks better for what i'm trying to say.

Both dynos are limited by the stock injectors.

http://www.flyinmiata.com/tech/dyno_...odooII_1.6.pdf

nothing wrong with superchargers. they're just not the best. here at mt we want the best. we are 1337 like that.

also there is nothing wrong with 200wtq at 2500. in fact, anyone that claims it sucks or you don't need it there obviously doesn't enjoy a VERY fun street car. throwing you back in your seat and hauling arse without having to be wound out to redline is a wonderful feeling. I enjoy it daily.

AND YET

there's absolutely no reason you can't achieve this with turbochargers. just run a small enough one. Its been proven too many times to count that a well set up gt2554 setup will embarrass the common supercharger setup on our cars. it is better EVERYWHERE


*****short version:
https://www.miataturbo.net/attachmen...ine=1339905689

Interesting, I assumed a supercharger would run cooler than a turbo. I'm not sure it's something I'd do anytime soon as I already have a TA with a LS1 but the thought of more power in my Miata is always in the back of my mind.

I had an M45 Jackson kit for about six months running 10psi intercooled with meth injection. Was the car quicker than a stock miata? Hell Yes. Did I get beat routinely in any kind of acceleration incident by a turbo miata with 10psi? Yes. That "massive amount of torque at 2500rpm" didn't really amount to dick considering overall power achieved was greater on the turbo car. . .

It was a very interesting experiment none the less but my conclusion is that I'd never have another positive displacement charger on a miata again. Ever. Granted the JRSC M45 was the shittiest blower made for this specific car, I really got tired of buying belts every 2 weeks and having to tighten them almost every day or it would start slipping.

Racing around with friends in their lightnings or 03/04 Cobras the sound of an Eaton coming at you always made me giggle but after owning and driving Turbo cars, screw these blowers. Even with WMI and a semi-quality FMIC my IATs were way higher than the turbo miata I tuned. Much to my surprise the FMIC didn't really seem to change the throttle response / power transition a single bit, even though I increased the intake manifold volume by several liters in the process. :giggle:

https://www.miataturbo.net/attachmen...ine=1339907743


That's my perspective on SC Miatas. For the type of driving I'd be doing in basically any vehicle I owned, turbos are by far a greater match in the long run.


You could always buy a used ForFucksSake Cold side Yo-Yo Charger from tann3r AND turbo it. . . . Just throw away that powercard crap and get a REAL fuel solution running FOUR properly sized injectors via Hydra/AEM/Adaptronic/FAST/Megasquirt/Tec/Etc.


Here's an article on compound boost (Turbo pushing air into blower): http://www.musclemustangfastfords.co...a/viewall.html

Positive displacement superchargers are not the only ones available. I guarantee mine is cooler than a turbo. I have less area under the curve, I admit.

Many years ago I drove an M62 + TDR i/c setup on a 2000 miata with some kind of fuel and timing box.
My car at the time had the GT2554.
My car made more torque everywhere. Even at 1500 RPM. Weird, I know.
And his car had endless pinging issues.
Additionally, the M62 setup had some weird unpleasant vibrations, at certain RPMs. Dunno if this has since been fixed.

And yet you have less torque under curve than both discussed here. Ouch.
No offense, but I think the failtrex kits were the biggest let down ever. We (or at least me) expected greatness when it was being hyped up by Emilio and others.

Roots blower through the hood or go home.

I'll take the reliable car that drives like a C6Z. That means turbo > hand-dryer.

Just to be fair, the biggest knocks on MOST sc'ed set ups are the lack of real engine management, the fact that they are bolted to stock motors and the fact that MOST of their owners are clueless. It's more than possible to have a M62 setup make as much or more power then most turbo setups and to have perfectly linear and transitional throttle response. BUT it does get hot without water, it does kick the belt from time to time, it does require C12 or E85, it is a purpose built motor and it does whine like a MF'er.

I still say it all comes down to what your plans are with the car, what your fab skills are and what your budget is. I love the way my car instantly pulls out of a 35mph tight sweeper in second gear(1,500rpm) after being at TPS=0 for 2 seconds all the way to 73.4 mph in second. In a properly sized turbo car that's going to be more difficult to accomplish. That being said there are a number of reasons my car wouldn't survive a 30 min session on a road course, one of the biggest is heat.

Im about to build a twin charged BP4W. As a bit of a fabrication exercise.

I intend to run an SC14 bottom mount hotside, with a filthy big turbo high mount. Perhaps a t3/t4 hybrid.

I would NEVER run just a blower.

Dann

^^^While a neat novelty the added weight and complexity of such a setup would not make it a viable option for just about any form of competitive driving^^^

This is a common perception, and it's certainly easy to understand why. We've all seen pictures of turbochargers glowing red on the dyno.

But what really matters for our purposes is not the temperature of the turbine housing, it's the temperature of the air being emitted from the compressor.

Centrifugal compressors have a higher efficiency than positive-displacement compressors. It doesn't matter whether the compressor is being powered by exhaust gas or a belt, it's all about the style of the pump. For our purposes, this mostly means that centrifugal pumps heat the air less as they compress it.

So with a positive-displacement supercharger, you are using more energy (from the engine) to turn the screws, and also creating more heat as you do so. BHP will always be lower for a given BMEP, owing to the power lost to turning the supercharger. And BMEP will always be lower for a given Mainfold Pressure, owing to the reduced density of the air.


Does this mean that supercharged engines can't make big power? Of course not. The dyno sheet that mgeoffriau posted is one of many showing big-number supercharged engines. But because of the lower efficiency, we can universally state that the same engine, if fitted with a turbocharger and otherwise in a comparable state of tune, would tend to make more power for less money and less fuel consumed. And we're not simply referring to peak power as is often stated, but total area under the curve.


So it's kind of a lose-lose proposition.


Now Mobius has pointed out that there are some superchargers which use centrifugal compressors. Within the Miata community, the Rotrex is probably the best known example in the present day. These devices are not without their charms, however they do suffer from one annoying weakness- with a centrifugal compressor, the mass of airflow through the pump is not linearly related to the speed of the pump as it is with a positive-displacement unit. At low speeds, centrifugal pumps hardly work at all, and the result is that boost with such a system rises with RPM. Low RPM = low boost, thus negating the usual (if highly exaggerated) selling feature of superchargers in general. Of course, this can to some extent be rectified by altering the pulley / gearing ratio of the unit to increase its speed, but you have another set of limitations at the top end- you can't exceed the compressor's own redline speed, and you have to figure out some way to cause it to stop making more boost beyond a certain point, usually by placing static restrictive orifices (like the restrictor plates used in NASCAR) at its intake.

So why don't turbochargers also suffer from these flaws? Because the shaft inside a turbocharger isn't mechanically coupled to the engine. It's free to spin up to a very high speed even at low engine RPM (provided that it's been sized properly), and then at the high end we can easily regulate its maximum speed by using a wastegate to bypass the exhaust around it.


Does this mean that centrifugally-supercharged engines can't make big power? Again, that'd be a no. But as with the first example, expect it to cost more, be more complex, and produce a less desirable torque curve.




In the end, it all boils down to a very simple question: what is the "best" way to achieve the goal of having a fast Miata, or a fast car in general?


Consider the following: If Lotus dropped the price of the Exige to $5,000 tomorrow morning, would it still be possible to build a Miata which was faster than a stock Exige? Of course- the science doesn't change. The only difference is that now, you'd have to be a damned fool to do so, and the Exige owners would be fully justified at laughing their asses off at anyone who tried. The Exige is a "better" platform to build from, and if it's also cheaper, then there's no justifiable reason for buying a Miata anymore.

Substitute "Turbocharger" for "Exige", and "MP62" for "Miata", and the basic logic remains the same.

I'd wonder how different this thread would have gone on a supercharger forum.

https://www.miataturbo.net/attachmen...ine=1339946775

http://www.mayer-johnson.com/power-c...me-and-autism/

Umm, 35 mph @1500 RPM is more like 6th gear.

https://www.miataturbo.net/attachmen...ine=1339947320

Very fun and easier to drive autox than my 94 with a 2554r.

For street driving I definitely prefer the turbo. This is purely because of my driving style. With the turbo I get the nice rush of torque down low and shift at a leisurely rpm. I drive the centrifugal the same and I miss my turbo.

But driving to, and close to redline and the super feels wonderful.


I am still debating whether to keep the super (quieting the exhaust), or go through the effort of swapping in my turbo bits.

Btw, does not eat belts.

Kindly expound.

Do you have TPS controlled boost in your 94?

I have the opposite (not exactly) experience. My E36 M3 has a centrifugal supercharger, and my miata with the GT2554 is easier to throttle modulate at autox. Possibly due to TPS controlled boost (and low 5 psi wastegate can).

Man thats one sharp ass elbow.

Jason, not a rotrex, but a VF Engineering. I think the model is a V9, without looking. 10psi at redline.

Did not have TPS controlled boost on the 94, just a MBC running 12psi with 3" exhaust attached to the crappy begi S downpipe.

Never drove a TPS based, so not sure how that effects things. Maybe I could be faster in the 94 if I knew how to drive and predict the power onset better.


Not sure if the compressor housing can be rotated.

Its easier to drive because its slower. Slow cars are usually easier to drive.

Joe, you should get the MT medal of honor for this post:party:
+100
There isn't a MIATASUPERCHARGER.NET.

That should tell you something.
:giggle:

I has supercharger. It's a nice day driver and autocross car. Oddly enough, I post better times naturally aspirated than I do with the supercharger on.

If I went back 3 years, I may have decided differently on the system. I'm satisfied with the power I've got, although it is barely enough to outrun the new precedent of 250hp Korean crossover SUV's.

My biggest battle has been maintenance actually. It's been a PITA to pull the supercharger off to service a loose egr tube/cap or calibrate the 02 sensor or change the clutch. I've probably had the supercharger off or loosened in order to adjust the belt alignment 6-10 times since I've installed it. I don't think I'd be pulling off a turbo that much...

The author there doesn't realize there's a difference between twincharging and compound boost. When I read compound boost, I think of this:

https://www.miataturbo.net/attachmen...ine=1311962164

Interesting.. I think it's a matter of semantics really, I've always understood using a compressor to feed any compressor is compounding..

http://www.lsxtv.com/news/granatelli...early-1200-hp/

All the stuff i've done to my kit since i first installed it.. During my install i realised begi sent me the wrong bolts from turbo to downpipe (either that or the person that sold me the kit bought the wrong ones)... Anyhow during my install i installed them and then next day i bought new ones to replace the short ones. Then i had the 2 pieces of the downpipe welded together since i didnt like the shitty slip fit design (was leaking and coming apart everywhere) After that i did an intercooler install about 3 months after installing the turbo. 2 weeks ago i checked the bolts on the turbo.. everything is perfect. i've had 0 reason to do anything else to my turbo after the initial install. Obviously other than essentials for the motor. I've been turboed for about 2 years now.

I'm just following TNTUBA around posting on anything he's been posting on, since we have similar SSM goals in mind. Also, I'm completely unable to leave a thread alone with people crapping on superchargers. It's a personality fault of mine.

This is my twin-screw supercharged power curve:
https://www.miataturbo.net/attachmen...ine=1341269331

It's about as flat as you can get, and makes it much easier to drive since it's predictable, linear power all the way through the curve, and it modulates with the throttle pedal in a predictable, linear fashion.

A turbo will never do that. Turbos are great for the track where you're just modulating mid corner and then flooring it on exit from a high RPM, but when you need to constantly go on/off gas and get the most power you can (i.e. autocross,) a twin screw supercharger is unbeatable.

A normal (M/MP) roots is okay, but tends to fall flatter on its face at higher boost at higher RPMs. For low boost they're fine. A centrifugal is all the worst parts of a turbo (power lag), without any of the advantage (laggy but still AVAILABLE torque at low RPMs) and is only useful for a track car with a VERY close ratio gearbox to keep it up in the boost. In that circumstance I'd still choose a turbo over a centrifugal SC since you can get so much more maximum power without parasiting it all away. Centrifugal is mostly just cheap and easier to plumb since it's small and can drop in a spot that has an A/C compressor or power steering pump...

https://www.miataturbo.net/attachmen...mathjtdall-jpg

All out turbo motor for comparison. Same dyno! got to be ready for the wall of torque that hits at 4000 rpm and a tiny bit of response lag mostly at lower rpm's.

owned:laugh:

And which one of these cars was faster this weekend?

What is done to the twin screw setup? How much money invested? Lets start there.

your "friend" likes to post dyno plots with no parts list or setup, then say something crummy about turbos and disappear

Can you read? He has a link to his build in his signature?

I got my ass handed to me. But we put miatas on top of the fleet of vetts vipers and RX7's.

I think Race logic traction control, Quafe Transmission so you can go fast enough in second gear, and a better rear wing were an advantage for David. I also think I got some suspension setup issues. maybe half of the differance could be chocked up to that. The other half he just out drove me.

Another thing was it was Goodyear vs Hoosier but I dont know what the differance there is.

Bob

Good job putting the Miata's on top. Now we all have to work to do it when the "real" RX7's are there.

signatures turned off:facepalm:
thanks for being a devensive a$$hole tho:giggle:

I'll check it out.
(PS: I do think his plot is impressive, don't get your panties twisted)

I try :) .........Anytime

You can't get your panties twisted........if you don't wear any :)

Bob: Are you running a 6spd? The quaife set really is perfect for autox... I think autotech has 2 kits left -- you should pick one up, especially if you're talking about building an XP miata.

BTW, We should spend some time Friday figuring out how to tune our wings. I bought a giant spool of pink twine from harbor freight for the purpose. :D

The goodyear vs hoosier thing is really interesting, and I think a lot of it comes down to driving style. I wish there was a good way to get really good data on the two tires, but the setup changes for the two tires on an SSM car to optimize them differently are huge...

But I don't have a dog in this fight. I don't think I would have anything for either one of you. My Co Driver might....but I have no skillz.

FWIW Scott Frasier still kicked both our asses running in CSP also in the same run group.

Bob

Scott is a machine. I was texting him Saturday night asking him if he just ever got tired of winning.

Total expense list for the build: Expense Log - DestinationSSM
Powertrain details for the build: Engine - DestinationSSM

Motor: Around 4500$ all done, half of which was the machine shop labor charge. In the end, I still think I overbuilt it, but I'd probably do about the same thing again if I had to start over. I'd spend a little more money on it if I were going turbo (stronger rods probably,) but it's a very very similar build to a high power turbo build.

Supercharger head unit: 2000$
SC crank pulley from FFS: 150$
Manifold from Corky: 860$ + infinite headache
Intercooler: 80$ + maybe 100$ of fab time
Intercooler piping: 100$ + maybe 100$ of fab time
RB header: 425$
Custom 3" stainless exhaust: ~1500$
AEM: 950$

In the end, the motor build, exhaust, and AEM are identical to what I'd do/have to pay for on a higher end turbo build. So, the SC "kit" is around 3000-3500$, depending on how much you can do yourself and how much you have to pay a welder to do.

Still got the 6 speed 3.636. 7400 rpm rev limit tops out at 60.3 mph in second. I kept blowing sound on sunday bouncing off the rev limiter past sound station. Just wasnt quite enough I think to warrent 3rd though.

Bob

Just looked over some of your site. Pretty sweet actually. Why can't more SC guys be like this. If there were more people like you and TNTUBA here maybe, just MAYBE we wouldn't hate on the sc guys so much:D

Yeah, sunday. I got him by quite a bit saturday. I left multiple seconds on the course sunday, which I fully admitted all run group sunday, and my PAX paid for it. :)

I think the courses were terrible for any cross class comparison, though. There were very few sections to use any power. I think our cars were basically overweight CSP cars for most of this weekend, especially on Sunday. I was just happy to stay ahead of Scott overall by 3 tenths for the weekend. :)

Awwww that's the sweetest thing anyone has said about me in years :)

Not all us blower guys are douches. I will freely admit I'm a jack ass....but not a douche.

David's car is breaking my heart. I had been thinking all winter I was going to have a bad Autocross Miata......and he had to come along a take it up a few notches.