When You do the carb thing yes the secondaries are open all the time... They're controlled by solenoids from the ECU...
The '84 '85 GSLSE had the ports are controlled by exhaust backpressure... With those the 6ports won't open if a free flowing muffler and headers, that aren't tuned, aren't used...
They're are some kits that use the stock lower intake and down or side draft webers for the upper... The right manifold and and a SuperTrapp might get around this... though I've never seen it done...
Rotaries get BAD mileage... I once got 11mpg with my turbo and considerded that good... I fixed the AC and used it ONCE... 4mpg!!!
As far as porting the 6port. There's a lot you can do to the primaries before you hit water. But since the secondaries are already open and huge... Look here for some more info...
Rotary vs Turbo VS Nos
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Jim Molloy
- Posts: 203
- Joined: Fri Jul 21, 2000 12:01 am
Rotary vs Turbo VS Nos
Here's a couple of web sites I vist quite
often.Lots of ideas , facts, bs.Sort thru it
ask questions and make your decisions."http://www.mazspeed.com/"and
"http://www.rx7club.com/index.php" Just cut
and paste.Good luck.
------------------
72 SuperVert w/12A Rotary engine.
Unique is what we seek,bizarre is what we are
often.Lots of ideas , facts, bs.Sort thru it
ask questions and make your decisions."http://www.mazspeed.com/"and
"http://www.rx7club.com/index.php" Just cut
and paste.Good luck.
------------------
72 SuperVert w/12A Rotary engine.
Unique is what we seek,bizarre is what we are
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spootman
- Posts: 97
- Joined: Mon Jul 30, 2001 12:01 am
Rotary vs Turbo VS Nos
I have no experience with this, but I have heard that rotarys got ok milage when they were new, but worn ones get much worse gas milage. The 1st gen rx7s got 22 mpg from the factory, apparently.
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Splortch
- Posts: 1
- Joined: Fri Feb 08, 2002 12:01 am
Rotary vs Turbo VS Nos
originally posted by MzQ: "Rotaries get BAD mileage... I once got 11mpg with my turbo and considerded that good... I fixed the AC and used it ONCE... 4mpg!!!"
It seems a bit unfair to badge all rotaries as gas guzzlers. My '86 N/A 13b 6 port FI gets about 17mpg around town (and I stomp on it a LOT), and 18 to 20 highway. The engine has well over 100k on it, but an older 150k engine I had got nearly the same mileage. Obviously a carb or turbo won't be as efficient, but depending on the setup, decent mileage can be obtained. With a good condition 13b, 24 or 25mpg is possible on the highway. Besides, an N/A will sip on the lowest octane you can find. It beats filling up with 93 and octane booster for a built piston engine
.
Also, I have my 5th and 6th port wired open, so they are open all the time. Mine weren't functioning, so I had nothing to lose. A slight loss can be noticed down low, but it's more than worth it to have the power that should've been there in the first place up high. It's Mazda's version of VTEC. Another option is also to remove the sleeves entirely, which nets little or no loss in the low-end, and noticeable gains higher in the powerband.
calereeves: the gains in porting a 6 port are generally not worth it (unless one wishes to go to a peripheral port, which is not only very expensive, but generally considered unstreetable). Rotaries like a free-flowing exhaust and intake. Keep that in mind, and you can make fairly cheap power. (For example, a $200 Racing Beat header and $20 K&N style filter will give you a NOTICEABLE gain over stock, and you will like it!).
It's quite possible to make 200rwhp reliably from a non-turbo rotary. The real problem is not extracting power from an engine, but making the parts of the Bug strong enough not to break!
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86 RX-7
85 MR2
It seems a bit unfair to badge all rotaries as gas guzzlers. My '86 N/A 13b 6 port FI gets about 17mpg around town (and I stomp on it a LOT), and 18 to 20 highway. The engine has well over 100k on it, but an older 150k engine I had got nearly the same mileage. Obviously a carb or turbo won't be as efficient, but depending on the setup, decent mileage can be obtained. With a good condition 13b, 24 or 25mpg is possible on the highway. Besides, an N/A will sip on the lowest octane you can find. It beats filling up with 93 and octane booster for a built piston engine
.Also, I have my 5th and 6th port wired open, so they are open all the time. Mine weren't functioning, so I had nothing to lose. A slight loss can be noticed down low, but it's more than worth it to have the power that should've been there in the first place up high. It's Mazda's version of VTEC. Another option is also to remove the sleeves entirely, which nets little or no loss in the low-end, and noticeable gains higher in the powerband.
calereeves: the gains in porting a 6 port are generally not worth it (unless one wishes to go to a peripheral port, which is not only very expensive, but generally considered unstreetable). Rotaries like a free-flowing exhaust and intake. Keep that in mind, and you can make fairly cheap power. (For example, a $200 Racing Beat header and $20 K&N style filter will give you a NOTICEABLE gain over stock, and you will like it!).
It's quite possible to make 200rwhp reliably from a non-turbo rotary. The real problem is not extracting power from an engine, but making the parts of the Bug strong enough not to break!
------------------
86 RX-7
85 MR2
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goatmaster187
- Posts: 351
- Joined: Thu Nov 29, 2001 12:01 am
Rotary vs Turbo VS Nos
Regarding the tranny issue, you can pick up a three or five rib Bus tranny for $50 to a few hundred bucks. As a plus they are geared low for a high spinning engine. My tranny guy makes an adapter to fit a Bug nose cone so mine bolted right in. It's kinda like the Berg setup.
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sinistervw
- Posts: 699
- Joined: Fri Jan 25, 2002 12:01 am
Rotary vs Turbo VS Nos
with a turbo you can actually get better VME and increase gas milage, this is if you use low boost and tune your fuel delivery curve to turbo output (well this is true with piston powe; don't know about rotary though!)