RETed

Tell me when you get that dyno sheet!


-Ted

vaughnc

He's got one on his website, but it's obviously taken in the wrong gear or they started the dyno too late. Hopefully he's got some more that has a nice long graph where you can see secondaries kick in and real boost levels at lower rpms.

Evil Aviator

http://www.geocities.com/boatseason/dyno.html

Looks about right to me.

RETed

Well, well, well - this gets VERY interesting.

I've taken that dyno sheet and plugged in some rough coordinates into Excel, and then took some points off of my dyno sheet to compare...
My dyno sheet:&nbsp http://fc3s-pro.com/PROJECTS/dyno1.jpg

I've plotted both the "low boost" and "high boost" lines to compare, as the "low boost" run is more comparable on pure numbers with the SC run.

SC:&nbsp peak HP - 209.9, peak torque - 173.5
"low boost":&nbsp peak HP - 237.0, peak torque - 194.1
Notice, both dyno runs were done on identical DynoJet 248C models.



NOW, I don't know what the set-up was on this FC SC that dyno'd, but the pics show a Zenki NA, so it's running at least the 9.4:1 CR rotors; i could almost kiss my 8.5:1 CR rotors right about now!&nbsp My car is a 1987 Turbo II with a matchport and polish job.&nbsp The dyno run was before the big street port job; my FC *was* running a T5/T6 compressor upgrade, which would produce a little more power than a stock turbo, but at the very least the stock turbo would produce almost identical numbers (power slope) as the SC NA would.&nbsp Who'd have thought the comparison would look like this. So much for the theory for SC's have "more" or "better" low end torque!

The numbers do not lie...



-Ted

BLUE TII

iTrader: (9)

He's running a centrifugal SC so I hope no one would think it would have more low end torque than a turbo.
All you NA guys that say you want a SC for low end torque need to take a ride in a TII w/ full open exhaust. Low end torque is tremendous. As a passenger it feels a lot like a bigger displacement engine; as a driver you will notice the very slight lag before the boost comes on. I have to repeat it is very slight lag. Imagine what could be possible by using a modern, very slightly larger than stock turbo w/ ball bearing center- instant boost and still more power than I have ever seen a SC NA RX-7 make.

Fingers

But Ted, you're forgetting that he hasnt ported his ride, nor done the portmatch/polish intake job. You have to at least admit that this kind of power out of an NA is impressive, even if the TII does have more low-end (not much more)

vaughnc

Fingers' is echoing what I was thinking. The 89+ 13b-t engine would be more efficient than an NA engine with boost at any rpm.

SuperchargedRex

Its nice to see a good discussion about supercharging. The dyno run from my website was run when I first installed the sc. I was/am running the factory ignition and fuel computers. The kit came with a boost dependent fuel pressure riser, and I added 550cc/min secondary injectors and the RP fuel pump. Intake was a K&N cone, exhaust consists of pacesetter header and dynomax cat and cat back. The motor itself was completely bone stock and had 124,000 miles on it.

One of the common fallacies about superchargers is that they all have all their boost available all the time; this is not true. A centrifugal sc delivers boost relative to engine rpm. Roots type blowers offer better low end power than a centrifugal.

Someone quoted a price of $7k for a fully functional sc setup, mine cost $4k. But I will be the first to admit that I limited my boost for simplicity. Craig Conley (who now owns the rights to the Paxton SN series of blowers) can modify the impellar for $200 so that max boost would be 18psi. You would need to throw probably $2k of fuel upgrades (Haltech and injectors), and then spend many hours developing your own fuel maps on a dyno, because no one has done it yet. I would also recommend spending a grand on an intercooler at this point, because you will need it. So that would put you at the $7k mark, but with 18psi of boost.

Scathcart, I know what you mean about offering kits. I recently went through the hassle of getting a shop to duplicate the mounting brackets and thermostat housing, and had a hard time selling 3 of them.

The Paxton SN series of sc use internal lubrication, 10 ounces of Automatic Transmission Fluid. They specifiy that you must change it every 3000 miles. There is also an add-on kit for a cooler for the ATF, if you're concerned about the heat.

Bottom line is, a sc isn't for everyone. But if you already have an NA that your attached to for whatever reason, and if you're willing to live with limited boost for a modest power gain, than the Paxton sc is a good fit. I would never deny that the turbo can generate as good as or better power, for me the sc was a personal decision. Plus, I just like being different.

Sorry for the length of the post.

vaughnc

Length?? Talk some more there superchargedrex we're all listening

Some self education is in order, so point us to a good book or website if you know of one.

I need to read up on centrifugal vs. roots; intercoolers, pluming, & disadvantages of intercooling, etc...

My pop's park avenue ultra has an OEM roots supercharger on it, and I do enjoy the throttle responce & seat of your pants acceleration it offers off of 89 octane (you were wondering RETed weren't you ). I didn't notice any fading at higher rpms, so I'm assuming they work pretty well at lower boost levels with higher rpms.

You mentioned an NA & imature fuel maps. If I start with a 13b-t engine in my convertible the haltech fuel maps "should" only need minimal tweeking for lower rpm boost. I'm assuming 8PSI is 8PSI no matter how it's delivered Then I just need to consider intercooling the air to make good HP at lower boost levels (18psi on a dialy is a bit much )

Of course the NA engine in the convertible could be modded, but I'm assuming the 13b-t engine would be a better candidate for supercharging.

Of course on your supercharged GTU-S you obvioulsy didn't want to remove the original NA engine (be true to the car).

I would like to see a new dyno chart with your mature fuel maps. I'd also hope your dyno company does it right this time (ie start the dyno recording in 4th gear at 1500rpms so we can get a better reading). Wouln't hurt to take her up to 45mph in 4th on the dyno and then punch it so we can see the boost kick in

SuperchargedRex

Sorry to dissappoint you Vaughn, but I've got an '88 SE and I'm still running the factory computers. And since my car was dyno'd at the now defunct Rampage Racing, they won't be touching the car again.

As for adding an intercooler, the two main disadvantages are the pressure drop as it goes through the core of the ic, and any lag that's created due to lots of plumbing. Which is one of the reasons I toyed with the idea of squeezing in an air/liquid intercooler in place of the elbow between the sc and the throttle body. Now you're talking about using a TII motor and intake, then you'd be set to use a factory intercooler. Of course, you'd be losing the 6 ports, unless of course you're simply talking about using low compression rotors in an NA motor.

Fuel maps might be an issue. I am not an expert, so the best thing I would suggest is to talk to someone like the Hitman who is extremely knowledgeable. My opinion, however, is that the fuel maps to the turbo might be significantly different if they are boost dependent. Think of it this way, with a turbo, you can spool up the boost regardless of rpm, not true with a centrifugal sc. Now, if you went with a roots style that makes full boost in a similar fashion, then the maps would be closer.

If you want to learn more about intercoolers, check outSpearco Intercoolers I found their catalog to have a lot of good info.

For good info about sc in general, check out the Tech section of superchargersonline

Hope this helps.

RETed

This can escalate into well-I-can-do-this argument, and it really won't get us anywhere.&nbsp You throw enough money into ANY car, and it'll go "fast".

What I was surprised with the numbers it he low end discrepency is just isn't there.&nbsp Now you can argue all you want about my matchport and polish job, but anyone with a bunch of sandpaper can do this to their engines in a few hours.&nbsp The motor was just not really ported - the exhaust ports were "squared" out a little, but the overall port dimensions wasn't touched.&nbsp This really doesn't constitute a "port job", as this was my first foray into "porting" my engine.&nbsp Most full exhaust 13BT's will put down about 230hp to the wheels on the DynoJet, and this is totally inline with the "low boost" numbers I had put down.

We are talking about a $4,000 SC kit.&nbsp With that kinda money, you can easily buy a very nice Turbo II.&nbsp My argument is start out with a stronger drivetrain if you want more power.&nbsp If you're happy with about 200-250hp, that's all the NA drivetrain can handle.&nbsp Most people will opt to have more power; there are very few which would be satisfied with 200-250hp on an FC (yes, I know you said this vaughnc!) - you guys need to take a ride on a 400hp one.

I'm still waiting for other dyno sheet - I'll punch all the numbers in and see where they all come out.&nbsp I realize this is only one example of a SC NA, but it's typical of most applications.&nbsp I dunno about the 18psi pulley - that's going to surely blow your car up with no intercooling.&nbsp I've messed with a friend's Honda Civic with a JR SC, and we went from a 6psi pulley all the way up to a 15psi pulley (custom); let me tell you, the amount of timing that had to be pulled at anything over 10psi is stupid and surpressed too much power - the car made GREAT gains in power from 6psi up to 10psi, but from 10psi to 15psi it didn't do jack cause of the hotter intake charge and extremely retarded timing to get rid of detonation.

/RANT ON
The ONLY kits I'm really go up against it the Nelson/Paxton kits.&nbsp Don't be throwing in Roots type SC kits unless you show me a kit that does this with the stock fuel injection.&nbsp That POS carb'd kit is a waste of time in my book due to the carb conversion.
/RANT OFF

I've seen the Nelson SC kit pump up 230hp to the wheels (OLD SCC mag), so I know this kit has more potential.&nbsp Right now, I heard a lot of sqwaking, but no proof of all your claims.&nbsp Please, don't go arguing me about the advantages of the (FC3S) SC kit unless you have dyno sheet to back it up...&nbsp Right now, the whole SC "advantage" is no where to be seen with that last Excel graph.



-Ted

Evil Aviator

First of all, you guys need to get past the idea that you need to download some magical EMS map from the internet that will be "close" to your setup, and then tweak it. All aftermarket EMS units that I know of ship with a good base map, you set your idle, then start tuning at no load (neutral) through the rpm range, and then SLOWLY work your way up the load bands. Every car is different, so there is no point in buying an aftermarket EMS if you are just going to use someone else's map, as a "high-performance" chip would do the same thing (partially tune your engine) for half the price.

Secondly, 8 PSI is not 8 PSI!. The air/fuel ratio which is maintained by your EMS is based on mass (weight), not pressure. The efficiency of the compressor will affect how much the air is heated under compression, which will determine the mass airflow at a given pressure. Every supercharger (including turbosuperchargers aka "turbos") has it own distinct characteristics which is shown on its respective compressor map. The characteristics of the intercooler (or lack thereof, lol) will also affect the mass airflow into the intake manifold. If you can understand the concept of a cold air induction system, then I think that you can understand the value of an efficient compressor and intercooler. BTW, Roots-type superchargers are notorious for poor efficiency.

Just a guess, but I would imagine that since the 6-ports were retained, the purpose of keeping the NA engine was to maximize the low-end torque.

You just can't beat Corky Bell's new "Supercharged!" book. Yes, he once agin omits the rotary engine, it has a lot of his opinions and some physics errors, but it covers all of the different types of superchargers, intercooling and exhaust principles, and everything else that you need to know in order to build your supercharged engine.
http://www.amazon.com/exec/obidos/ASIN/0837601681

vaughnc

So I think we've started touching on overcoming some of the disadvantages of supercharging.

- Intercooling - possibly the stock TMIC will help
- fuel maps - OEM haltech maps are a good start in tuning
- platform - turbo II engine & drivetrain is a bit better
- current dyno chart - flawed as superchargedrex is using the OEM computer. Still a good sign of potential
- main advantage - medium HP/torque improvement with near 0 lag & better torque in the 1500-3500 rpm range
- chassis cooling - ATF self cooled
- chassis lubricating - ATF every 3000 miles
- TII, 4 ports, & low rpm torque? - yes
- NA, 6 ports, & low rpm torque? - yes

Most car manufacturers are getting 40-80more hp from low boost on supercharged cars. That's a good indication 100hp on an intercooled supercharger with medium boost should be very possible. More R&D needed though on my part

Evil Aviator

That's totally false. Superchargers also take some time to get to the rpm in which they are producing a significant amount of boost. They will generally have much less lag than a large turbocharger, but twin sequential and dual scroll turbochargers begin to close this gap as you have seen with RETed's comparison.

The 4-port vs. 6-port issue gets kinda sticky. Generally, for low-boost applications, the 6-port will help with the low-end torque, while the 4-port flows better at the high end. We could have a huge debate on this concept alone, but I think that it still comes down to personal preference. However, I think that most will agree that the 4-port lends itself better to porting, which is the track that you want to be on for high-boost engines.

I think that the SC issue comes down to whether or not it is worth it for you to spend 4K for your car to look and sound unique, at the cost of being slower than a TII with the same amount of money in engine mods. I think that it is safe to say that the SC will give better performance than a stock NA.

Felix Wankel

All this reminds me of supercharging an air-cooled VW. It works alright, but you're mainly spending money just to be different

Evil Aviator

There's nothing wrong with that, just as long as you realize it.

SureShot

My fantasy: The Paxton kit - with a viscous clutch torque converter like the fan clutch. The blower reaches max RPMs when the engine is at 5k and holds that as the engine revs higher. I'm thinking - not huge power, just more fun sporting around town.
Bill

vaughnc

check that quote again evil aviator:

Diddo sureshot's thoughts.

Just more power for putting around town in the convertible. More streetabable power is all I need. No stiff clutches or MADD power rushes here

Poindexter10thae

iTrader: (2)

I think the main problem is that the kit is so damn expensive, 3,000 last time I checked. If you got the cash, go for it. dont worry about breakin **** until it happens

SuperchargedRex

Sorry, I don't have any other dyno sheets posted, and since I haven't made any other modifications, I don't intend to dyno again. And I agree with you, if you upgrade the impellar to 18psi, you will need an ic. (I said that in my earlier post.)

I posted my dyno sheet with all my mods. I have offered some suggestions on how to gain more power from the supercharger, and given the pros and cons of those suggestions. There are advantages to the sc; its a relatively simple bolt-on that came with a C.A.R.B. sticker, so you can pass both emissions and a visual test if necessary. I have repeatedly passed with my setup.

I keep hearing the argument that if you want more power, get a TII. But if you just want some more power for your NA, especially if its a convertible, than the sc can be a viable option. I've been asked why I've dropped off the board lately, and this is a prime example.

vaughnc

duplicate - slow forum.

vaughnc

Ah don't let RetED and the other knowlege guru's intemidate you. It's the old "why buy a apple/macintosh" debate all over again Reted still doesn't realize your using the OEM computer and the car's not tuned / ported to take 100% advantage of your setup. Good results with the untuned stuff though I wonder if the lower compression rotors, haltech, & minor port would help?

Good to have you back though. I've seen about 5-6 supercharged rotaries on the web, but only 1-2 people actually participate on the forums.

BTW - anyone ever build a "blower" drag racing rotary on pump gas or alchohol like the piston ones on the espn drag races? I know the 7sec rotary alchohol cars are mostly turbos.

My convertible project plan is to do the TII conversion first. Once the car is tuned on a haltech & factory turbo I'll swap in the supercharger (and those mounts will be fun to find/fabricate). I'll probably try the OEM TMIC to see how it does.

Samps

Felix Wankel

I don't blame you, this place is going downhill.

Mykl

I tire of the old "buy a Turbo II" option as well. Find me an '89-'91 Turbo II in acceptable condition, and perhaps we can talk. As it is, they're few and far between.

Then there's the old Jap spec 13BT swap, if you can get ahold of one that'll run and last.

I think the supercharger option is a very viable solution for the n/a owners who have modest power goals. It may not have the most potential, but not all of us want 400+ hp monsters.

I'm debating this right now. I can't figure out what to do with the convertible, track down a supercharger, Jap-spec, or just leave it alone and save up for an EVO or something. I've got the cash, just not sure where I want to put it.

SuperchargedRex - I value your opinion, if there's anything I can do to make the FC forum any better let me know. I haven't been around much, but I can do a bit of cleaning up if necessary. That goes to anybody, my eMail is myklbw@bellsouth.net . If you write, make sure to include your forum name so I know who you are.