Turbo or Supercharge
05-10-2007, 12:56 PM
#2
Senior Member
Join Date: Nov 2001
Posts: 2,284
Superchargers are good for low end to mid kick. Turbos are good for mid to high end kick. It depends on your prefered driving style.
My friend's SC 13B in his '81 is very excellent. It has an aluminum flywheel and will break them loose in gear from a roll. The carb is right out of the box. Very easy to install the SC and very easy to get it up and running. Plus if you already have a great exhaust system, like the Racing Beat dual pipe "street port" system, you get to keep it.
He also installed one in his REPU. It's a 7" and the belt slips a little. We're looking into it. It has a light steel flywheel and works great in the truck. It feels like a GSL-SE flywheel with an HD disc. Not too bad to drive and he tows with it.
I installed an SC on my Bro's RX-4 wagon and it woke that thing right up. We used a GSL-SE flywheel but with the added rotating weight of the SC, it feels more like the old stock 30 pounder. He's going to get a light steel flywheel which should work perfectly in that heavy beast.
I'm biased toward the superchargers because I've done a few. I think they're great. Excellent driveability and low end. High end is fine too to tell you the truth. However if you're trying to get maximum high end and only high end with relatively poor regular driveability, a big turbo is probably for you. Otherwise a modest turbo would probably work. Also plan on getting a large diameter exhaust with not much muffling because the turbo reduces much of the noise as most of the exhaust energy is spent in spinning the turbine. You're just trying to dump it so 3" is appropriate I think. Must make room for a front mount intercooler, all the tubing etc. Must also use an ECU; most likely aftermarket stand alone. Send and reurn fuel system that can handle increased pressure of like 50 PSI. I'm probably forgetting some stuff.
Anyway if it was me, knowing both systems are probably going to end up costing about the same in the end, I'd go with an SC. I have too many other projects to worry about without the headaches involved in doing a turbo.
My friend's SC 13B in his '81 is very excellent. It has an aluminum flywheel and will break them loose in gear from a roll. The carb is right out of the box. Very easy to install the SC and very easy to get it up and running. Plus if you already have a great exhaust system, like the Racing Beat dual pipe "street port" system, you get to keep it.
He also installed one in his REPU. It's a 7" and the belt slips a little. We're looking into it. It has a light steel flywheel and works great in the truck. It feels like a GSL-SE flywheel with an HD disc. Not too bad to drive and he tows with it.
I installed an SC on my Bro's RX-4 wagon and it woke that thing right up. We used a GSL-SE flywheel but with the added rotating weight of the SC, it feels more like the old stock 30 pounder. He's going to get a light steel flywheel which should work perfectly in that heavy beast.
I'm biased toward the superchargers because I've done a few. I think they're great. Excellent driveability and low end. High end is fine too to tell you the truth. However if you're trying to get maximum high end and only high end with relatively poor regular driveability, a big turbo is probably for you. Otherwise a modest turbo would probably work. Also plan on getting a large diameter exhaust with not much muffling because the turbo reduces much of the noise as most of the exhaust energy is spent in spinning the turbine. You're just trying to dump it so 3" is appropriate I think. Must make room for a front mount intercooler, all the tubing etc. Must also use an ECU; most likely aftermarket stand alone. Send and reurn fuel system that can handle increased pressure of like 50 PSI. I'm probably forgetting some stuff.
Anyway if it was me, knowing both systems are probably going to end up costing about the same in the end, I'd go with an SC. I have too many other projects to worry about without the headaches involved in doing a turbo.
05-13-2007, 05:07 PM
#3
Senior Member
Join Date: Jan 2006
Posts: 545
Turbo for the win, check out my dyno post over in the dyno section. My turbo is virtually lag free, but I have an electronic boost controller which makes a huge difference.
Roots type s.c. are terrible at best. If i had to put on a sc. definately would be a centrifugral one. and it would have to be intercooled. A little more money up front. But once again carbs are out dated by thirty years, and your going to want some kind of ignition control, so just do a turbo swap.
Jeff do you have any dyno sheets for the s.c. are they the camden brand? We going to have a dyno day in olympia in June, bring down one of them. Is the 81 rx7 Dan's?
Roots type s.c. are terrible at best. If i had to put on a sc. definately would be a centrifugral one. and it would have to be intercooled. A little more money up front. But once again carbs are out dated by thirty years, and your going to want some kind of ignition control, so just do a turbo swap.
Jeff do you have any dyno sheets for the s.c. are they the camden brand? We going to have a dyno day in olympia in June, bring down one of them. Is the 81 rx7 Dan's?
05-13-2007, 06:24 PM
#4
Member
Join Date: Dec 2004
Posts: 58
Originally Posted by woundup7' post='871680' date='May 13 2007, 03:07 PM
Turbo for the win, check out my dyno post over in the dyno section. My turbo is virtually lag free, but I have an electronic boost controller which makes a huge difference.
Roots type s.c. are terrible at best. If i had to put on a sc. definately would be a centrifugral one. and it would have to be intercooled. A little more money up front. But once again carbs are out dated by thirty years, and your going to want some kind of ignition control, so just do a turbo swap.
Jeff do you have any dyno sheets for the s.c. are they the camden brand? We going to have a dyno day in olympia in June, bring down one of them. Is the 81 rx7 Dan's?
Wow another Camden basher, big surprise. As jeff mentioned. turbo will give the most net hp. The camden does as advertised, nice thing about it is that it is simple and reliable. yep the s/c is carbed, again dated, however simple and user tunable. I rn the camden, it works great for off throttle response and torque. If you already ahve a fresh motor and want a streetable daily driver it is a great choice. On the other hand, if you are at square one with a blown engine and deciding which way to go, then no doubt about it, go TII swap with an upgraded BB turbo and a standalone. The TII route will cost more, but relative to hp you get way more for your money. Camden for a daily driver on an existing engine which is never looking to top 200rwhp, I mean never, that's it. TII transplant for an easy 300 with potential for 400+
05-14-2007, 07:43 PM
#6
Senior Member
Join Date: Jan 2006
Posts: 1,114
My vote is turbo. Better system for the rotary. Roots are old technology. That is just a plain and simple fact. Not trying to bash the camden unit. I would be interested to see a centrifugal unit on a rx7 though.
Are you running a 12a or 13b? turbo'ing a 12a is a tiny bit more complicated than a 13b. (custom manifold). In the end though it is not a huge deal.
Are you running a 12a or 13b? turbo'ing a 12a is a tiny bit more complicated than a 13b. (custom manifold). In the end though it is not a huge deal.
05-16-2007, 09:14 AM
#7
Senior Member
Join Date: Nov 2001
Posts: 2,284
Pulling out of the parking lot and sliding around:
http://media.putfile.com/Supercharged-RX-7-showing-off
In-car footage:
http://media.putfile.com/Supercharged-RX-7...wing-off-in-car
Revving the engine:
http://media.putfile.com/Supercharge...revving-engine
Donuts - short:
http://media.putfile.com/Supercharged-RX-7...ng-donuts-short
Donuts - long:
http://media.putfile.com/Supercharge...ng-donuts-long
http://media.putfile.com/Supercharged-RX-7-showing-off
In-car footage:
http://media.putfile.com/Supercharged-RX-7...wing-off-in-car
Revving the engine:
http://media.putfile.com/Supercharge...revving-engine
Donuts - short:
http://media.putfile.com/Supercharged-RX-7...ng-donuts-short
Donuts - long:
http://media.putfile.com/Supercharge...ng-donuts-long
05-22-2007, 11:32 PM
#8
Member
Join Date: Dec 2006
Posts: 57
Just a few things for the turbo heads around here ... you have obviously not checked out the Rotrex SuperCharger ... yes it is a centrifugal supercharger ... then you will argue that will take out the bottom end and be more like a turbo charger your right to an extent ... you have to also check out the 2 speed transmission for it from Antonov. The speed change can be adjusted via a solenoid for whatever rpm you want it to be switched at. So this is the solution for both top and low end boost. Check out their site and specs sometimes ... This is what I plan on doing and will have to custom make a bracket for it that will be attached where the AC pump normally sits. the whole system with oil weighs less than 10KG so fairly light too (this is without the transmission but I would say about 5kg extra for that looking at the pictures and size comparison.
05-23-2007, 06:43 PM
#9
Senior Member
Join Date: Jan 2006
Posts: 545
I seriously dont know where people come off saying turbo's have no low end, My set up makes full torque by 3500 and it stays there until 6000 and hits full horsepower at 7000. BTW I am not making this up its on the dyno sheet.
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