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FD3S Non-Turbo

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Old Feb 12, 2004 | 07:15 PM
  #26  
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if you use the stock ecu, you would be throwing a lot of extra gas into your engine. I bet it would do more bad then good.
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Old Feb 13, 2004 | 06:59 AM
  #27  
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I've seen some Japanese web pages list N/A FD3S. I don't remember how much HP they get, but it looked most of them were ported or PP'ed to get decent power. It looked like fun to me to have PP FD I wish I could!!!
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Old Feb 13, 2004 | 10:26 AM
  #28  
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you wouldn't need a special ECU...and they are same compression rotors as n/a....
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Old Feb 13, 2004 | 01:49 PM
  #29  
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I think it would fun as a daily car. I thoroughly enjoyed driving my '86 NA FC for 10 years as a daily driver. Bounced the needle to 7 grand + every day and for 135k miles on the same engine. Get more of a chance to row thru the gears and enjoy the chassis instead of going ballistic. Same ecu should work as long as the throttle position sensor does not think it has boost at full throttle (hopefully it uses the boost sensor). You'd probably get more help if you asked this in the Race Car Tech forum...
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Old Feb 13, 2004 | 02:14 PM
  #30  
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Bleh@na FD's. It just doesn't go together. Get an FB, port it and slap a holley on it. You will be happier and have more fun.
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Old Feb 13, 2004 | 02:17 PM
  #31  
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Originally posted by rotary-tt
I think it would fun as a daily car. I thoroughly enjoyed driving my '86 NA FC for 10 years as a daily driver. Bounced the needle to 7 grand + every day and for 135k miles on the same engine. Get more of a chance to row thru the gears and enjoy the chassis instead of going ballistic. Same ecu should work as long as the throttle position sensor does not think it has boost at full throttle (hopefully it uses the boost sensor). You'd probably get more help if you asked this in the Race Car Tech forum...

cmon guys, stop encouraging him. taking the turbos off of an already turbocharged car is retarded.
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Old Feb 15, 2004 | 01:04 AM
  #32  
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Originally posted by fastcarfreak
if you use the stock ecu, you would be throwing a lot of extra gas into your engine. I bet it would do more bad then good.
No. A lot more *air*. Maybe.

The FD uses a speed-density computer. That means it takes the engine speed (RPM), the density of the air in the manifold (air temperature/pressure), and calculates the amount of airflow via an internal volumetric efficiency map.

By removing the turbos, obviously the engine would never see boost. So the computer would simply never go into the "positive manifold pressure" (over 14.7psia) part of the map. Big deal. Engine should run fine.

The only sticky wicket would be that there wouldn't be the exhaust restriction from the turbos. So the VE goes up, meaning for a given intake manifold pressure, more air flows through the engine. So the engine runs leaner.

But maybe not. How much exhaust restriction do the turbos represent when not under boost? Probably not *that* much.

So, to sum up, it'd run just fine. Maybe a bit lean, but N/A rotaries seem to like running leaner than typical at full power.

9.0:1 compression is slightly lower than normal for N/A - N/As have been mostly 9.2-9.4 compression, another couple points down isn't gonna hurt much. Again, airplane types take FD and Cosmo engines, scrape off the turbos, and run them as-is, and make decent power doing so.

- Pete (Boost spike? Whuzzat? )
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Old Feb 15, 2004 | 01:06 AM
  #33  
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From: https://www2.mazda.com/en/100th/
Originally posted by peejay
No. A lot more *air*. Maybe.

The FD uses a speed-density computer. That means it takes the engine speed (RPM), the density of the air in the manifold (air temperature/pressure), and calculates the amount of airflow via an internal volumetric efficiency map.

By removing the turbos, obviously the engine would never see boost. So the computer would simply never go into the "positive manifold pressure" (over 14.7psia) part of the map. Big deal. Engine should run fine.

The only sticky wicket would be that there wouldn't be the exhaust restriction from the turbos. So the VE goes up, meaning for a given intake manifold pressure, more air flows through the engine. So the engine runs leaner.

But maybe not. How much exhaust restriction do the turbos represent when not under boost? Probably not *that* much.

So, to sum up, it'd run just fine. Maybe a bit lean, but N/A rotaries seem to like running leaner than typical at full power.

9.0:1 compression is slightly lower than normal for N/A - N/As have been mostly 9.2-9.4 compression, another couple points down isn't gonna hurt much. Again, airplane types take FD and Cosmo engines, scrape off the turbos, and run them as-is, and make decent power doing so.

- Pete (Boost spike? Whuzzat? )
the fd ecu will just run off the 02 sensor until 3200rpms, and then go 10:1 rich after that, it should be ok
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Old Feb 15, 2004 | 01:54 AM
  #34  
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So even with less exhaust restriction making VE go up, it'll still be excessively rich, just like an FC N/A?
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Old Feb 15, 2004 | 02:45 AM
  #35  
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ive ran my FD n/a once or twice before....(forgot to tighten a hose clamp on a IC coupler, lol) my friends civic 5spd was faster. I wouldnt ever recommend doing that though, because you risk majorly overspooling the turbos. If you want a n/a rx7...pick up a FC for $1000...keep the FD turboed. And a n/a engine swap will be entirely too much trouble and money to make it worthwhile
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Old Feb 15, 2004 | 10:34 AM
  #36  
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Even *I* would rather have an FD over an FC, given the choice. And I'm an "older is better" kind of guy. Much nicer suspension, for starters.

There is (at least) one racing class where FDs are permitted *only* if they are non turbo. Peripheral port OK. They do fairly well.
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Old Feb 15, 2004 | 05:17 PM
  #37  
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tell you what, why don't you just put a chevy v8 in it and go away.
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Old Feb 15, 2004 | 05:25 PM
  #38  
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From: https://www2.mazda.com/en/100th/
Originally posted by teamstealth
ive ran my FD n/a once or twice before....(forgot to tighten a hose clamp on a IC coupler, lol) my friends civic 5spd was faster. I wouldnt ever recommend doing that though, because you risk majorly overspooling the turbos. If you want a n/a rx7...pick up a FC for $1000...keep the FD turboed. And a n/a engine swap will be entirely too much trouble and money to make it worthwhile
pull of turbos, replace with rb header, done 8
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Old Feb 15, 2004 | 08:43 PM
  #39  
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If money is not a problem you can order an engine from japn built by AR-F they have made non pp-port engines (I think, probably wrong) ranging from 250-35- rwhp and have developed a special exhaust that reduces the db down to only 110. Also Top Fuel had posted NA engines. There was one more Ijust can't think of. I am sure in the end when comparing costs going single is the best choice. These cars are not as fragile as you think I am on my second set of turbo and my engine is almost at 115,000 milesand I can still smoke a Z-28.
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Old Feb 15, 2004 | 09:12 PM
  #40  
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Originally posted by rotary-tt
You'd probably get more help if you asked this in the Race Car Tech forum...
True, there are some n/a FD's running in SCCA where they did not allow turbos untill just recently, and then in a real funky regional class. SP1 I believe.

Last edited by cpa7man; Feb 15, 2004 at 09:16 PM.
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Old Feb 15, 2004 | 09:36 PM
  #41  
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I really do like the idea of an N/A rotary, but turbo lag is fun. If money was no option, and you really wanted an N/A motor in an FD, I would go with a 4 rotor, like what scoot did. 500+ rwhp without a turbo, wow
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Old Feb 16, 2004 | 02:27 AM
  #42  
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NA FD isn't too bad of idea, if i had good money and time i would conside, of course we talkin peri port here right?
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Old Feb 16, 2004 | 02:29 AM
  #43  
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PP 13B-REW or 20B would be perfectly fine in an FD.
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Old Feb 29, 2004 | 08:02 PM
  #44  
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Thanks for everyones comments!

Tony
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Old Mar 18, 2006 | 04:17 AM
  #45  
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You guys suck

Have you ever seen some of the built up n/a fcs?
they gut em down and the FD already has a nice big port and a really **** motor,
just make a header and get a power fc. itd work great.
way nicer powerband, just not as much power. Would be awesome for auto-x and tight twisties.

Don't forget that the stock turbo crap does weight quite a bit, they may have cut down w/ plastic IC parts, but you can remove all of that crap and the stock twins and all of the rats nest associated with it.

I would only do this if I stripped the car down to actually take advantage of the lost weight of the turbos, something like 2300lbs and 200rwhp would be fun FD has really nice chassis pretty interior. im stuck w/ fc interior....

HATERS!
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Old Mar 18, 2006 | 09:30 AM
  #46  
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Wow, Node, bringin' posts back from the dead!

Dale
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Old Aug 9, 2012 | 07:32 PM
  #47  
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Back from the dead...

I guess the reason behind this is to still be able to drive your sexy fd, but have it much more reliable, and probably save a bit of fuel.
How often do you get to race people on the street anyway? Well i guess that depends where you live, but for commuting to and from work in a city its not going to be often, so no need for big power.

How about this, convert to straight lpg using the old mixer style setup, cheap setup, cheap fuel, and no need to worry about playing around with the ecu if it doesnt work so well without boost.

I think its a smart option...
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Old Aug 11, 2012 | 04:41 AM
  #48  
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just chuck a carb on, throw away the ecu all together haha. but yourd have to port it to get decent power. but a 48mm ida carb, on stock port would be a reliable 180hp. good on gas ish. and something different. stil cheaper to do new turbos
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