Sterling

I would like you to describe your set-ups, your opinions on performance, engine wear, and ultimately after having had both, which you prefer.
I would rather hear from those that have had identical engines and cars for each example, but don't want to limit it too much.

This is not intended to be some sort of end-all to the turbo-super debate, but rather a collection of opinions by those who have actually owned and driven for extended periods, both set-ups. No conjecture, assumptions, or speculations, or bashing in this thread- just the real deal.

No opinions or comments from instigators, please, but rather questions to the others that have this rare experience.

79+80+84_rx-7

I have a question..... say you have a supercharger with an 8 pound pulley...... does that mean it can make 8 pounds , or does that mean its 8 pounds at 850RPMS?


thanks, Andrew.....

Atkins Dan

STERLING : I have driven both cars (supercharged & turbo) and I like sc better and the reason is with an sc the boost is all ways there right off of idle . on the turbo I did not like the lag time but both cars were & are fun to drive .

79+80+84_RX-7 : when you run an 8 pound pulley that is ALL the pounds of boost it will make if you want more boost just change the pulley .

my sc car is a 1st gen and my cousin has got the 87 turbo2 .

BOOST IS BOOST and there more fun cars to drive than n/a cars .

CODE BLUE 2 your turn !!

Dan Atkins

mrmasda

I have sold and driven rotaries since 1976. I sold the last rx7s in the USA in the 90s and loved the dual turbo and was even able to take a stock and our winning rx7 of the Daytona 24 hrs for a thrill ride at Daytona. My nickname at work was mrmasda so I took it for all my personel tag. I own an 72 RX2 with a 5" supercharger I did not want the Electrics of the turbo but in hind site my car would be quicker at mid to top and I would have a current car. I have spent a ton of money on my labor of love,Aussie custom oil cooler, custom aluminum radiator,custom built holley carb,upgraded fuel system,gauges, and special air intake but then I would have had to spend also to turbo. The meat for me is that instant 9 lbs of boost at low rpm where the rotary has no torque. I have not touched the inside of my 13b for the 3(three) yrs I have been boosted. I have the light weight flywheel and 4.44 lsd and she jumps when the secondaries sing. The kit was installed by myself in a weekend and could have done it in one day. Both are great for us rotor heads and I hope one day to be able to own both at the same time then I could really hear my wife say you love those cars more than me but then she already knows that.

680RWHP12A

i have driven both s/c and turbo charged vehicles and there is NO comparison!!! turbo is way better!!
the sc car i had was a 85 se with a 6 port streetport with the camden sc kit. it was the big kit with the high boost pulleys on it..it ran good (low 13 sec on slicks), but not good enough...plus the s/c being a roots type did have some vibration wich i didnt like , since the rotary engine is so smooth...as far as performance goes, i have a 13b turbo (j-spec) with a 45 weber blow through on 10 psi with no intercooler, that makes 230 rwhp!!! with lots of room to upgrade!!

im using the 13b blowthrough as a comparison because it wouldnt be fair to use my 12a turbo

high-RPM

why not have both.... was thinking the other night how simple it would be to install both (in theory).... assuming that the supercharger has a electronic clutch, then it can be turned off via a switch. a pressure switch could be added to the xorst so that it turns the sc off when enough exhaust back pressure is being generated - OR when enough boost is being made by the turbo...

possible.... beit insane and expensive.... but possible none the less

imagine torque of sc with top end of the turbo....

smiles

just my 2c worth

- BennY

mar3

iTrader: (8)

there you go, sterling...

Sterling

People that lay out the cons for either a roots SC or a turbo state that the turbo suffers from lag while the SC has boost available from the start, and the SC runs out of boost up high while the turbo is increasing boost.

Of course, turbo lovers say that "turbo-lag" is not really that big a deal, while SC lovers say that their torque range is lowered so much that they don't really need to go that high in the rpms anyway.

I don't think I would personally be too upset by turbo lag, and it's probably a criticism most exploited by the pro-SC guys. It can pretty much be ironed out by someone who knows what he's doing -from what I've read from turbo owners. But these same people that have figured out how to virtually eliminate turbo lag still seem to think that there's just no way to improve the performance characteristics of a roots SC. (If they tried, they could!)

However, I hope to demonstrate with my project next summer that by stuffing a huge-*** blower under the hood in blow-thru configuration and boosting a ridiculous amount but bleeding off some of the boost, I can achieve a very healthy helping of roots-given boost from way down low all the way up to redline.

My supercharger set-up will be trying to overboost the engine, and the boost will be regulated primarily by a series of valves, not by engine rpms.
What do you think all those rats nest solenoids are for? They deliver signals at different manifold pressures, opening valves and tripping electric solenoids. Hopefully my "Manifold Pressure Dependant Boost Correction System" (MPDBCS?! ) won't be nearly the mess that the rats nest is, but there will be some complexities involved.

...just gotta think outside the box. Looking at a component (like a SC) and saying, "It is what it is." does'nt cut it with me. We're all smart enough to take something (anything) and make it better.

Rx7carl

From all I've read, its a matter of application for turbos. A small turbo will spool quick, but wont deliver max power. A giant turbo will make huge power, but the spool time (lag) will be significant. So running a giant turbo on the street would be kinda counter-productive IMHO. Just an observation. But what do I know, Ive never owned either.

mar3

iTrader: (8)

Fear not! We represent 25% of his poll as of 12/02/03 @ 1551 hrs CST....

REVHED

The problem with bleeding the boost off is that the blower is working harder than it needs to and will heat the air up accordingly. No? Of course it depends on how efficient it is at the higher pressure.

Sterling

The idea is based on the Eaton supercharger bypass valves. At cruise, the valve opens the intake to the compressed air side. In effect, the blower just spins around not really doing much more than circulating air. According to Eaton, it uses 3 HP in this bypassed mode.
I figure that can't be heating up the air.

Pulling the relief valve on an air tank causes it to cool down. The reason was explained to me in scientific terms along with an elaborate equasion, but I can't find it. Not sure I would even know how to apply it. But it leads me to believe that the compressed air will actually cool if it's bled off. -Whether it will cool down to the same temperature as the same boost achieved by usual delivery, I don't know.

All this may be moot for two reasons...I am intercooling, and I also intend to overboost just enough to achieve what I want.
I also plan on experimenting with water injection hopefully by the summer after.

luiml73

iTrader: (1)

I will now like to present exibit A

http://jackson57.customer.netspace.n...%20alright.WMV

fitzwarryne

I have not tried either in a rotary. However, some years ago we put a lot of time in comparing both in Ford-Lotus and Renault Alpine situations both involving Weber carbs.. The general conclusion was the SC produced the power earlier but not the peak later on. Thus, at fairly constant speed situations such as a track the turbo was better. In rally situations the SC was better. The critical point was the gearbox, 4speed was ok on a SC but with a 6speed close ratio box turbo had advantages. At that time good 5 speed production boxes were not around as 5th tended to be a lazy overdrive.