3 motors for a fc3s(2nd gen rx-7)

[blight]

Originally Posted by MclarenF1

Oh mah Gawd! That LS1 Rx7 is AWESOME! I've been thinking about my "affordable dream project" for a while now, and I'm pretty set on a RX7 with a smallblock. If you really want to go simple and effective, think about a Chevy crate motor with 2 big, sucking four barrels on top of it. No ECU or any of that junk to deal with. I've seen this on a couple of the 1st gen. Rx7s. Big motor + really small car= rocket. I think the 2nd gen. Rx looks better, though. I also think the Nissan motor would be out of the question. I own one, and that thing would be almost impossible to change over. The 2 rotor turbo from the 3rd gen. would probably be a bigger pain than you think, too. If I was going to do that, I would try to go all out and see if I could get a 3 rotor out of a Mazda Cosmo. But maybe that would be impossible. Not that a fuel injected LT1 would be easy, though.

so if i were to get a carbed 350 (i would stroke it out to a 383 stroker) with a carb instead (this WOULD be cheaper is assume) do i have to mess with ecu and computer crap?

[MclarenF1]

Since a carbed motor is strictly a mechanical set up, there is no ECU to worry about. A modern fuel injected motor has an engine control unit to adjust injector cycles (thus controlling fuel flow) in relation to the amount of air that it is able to pull in from the atmosphere (as read from the mass air flow sensor). Carbs do away with the injectors (or injector if a throttle body set up) and do exactly what their name implies- they simply mix the air and fuel and send them down the intake manifold together. Of course you would still have wiring to do, but just for speedometer, tach, temp gauge, etc. Just no sort of "central control unit" to hook into.

There are a few compromises, especially if you have been spoiled by computer controlled motors all of your life. Carbs can be finicky about proper tuning, cold weather starting can be annoying, and economy and effeciency aren't quite the same (but a well tuned motor can come mighty close).

The main advantage here would definately be cost. A fuel injected LS1 would be my dream swap (a great mix of speed and all around drivability), but you could buy a bone yard carb motor for a fraction of the price, and use the money you save to build the crap out of it. In the end, you would probably end up with a faster car for less money. Pick up a copy of Hot Rod magazine and do some price checking at performance shops. It won't take long to see why so many people still like to work over old fashioned motors. Lots of parts available for not so much dough. But, then again, Electronic Fuel Injection is a great thing, and older motors with this (like the LT1) probably aren't too terribly expensive. And once you get it hooked up, I think ECUs are really easier to work with. In ending, all I can really suggest is to look at your wallet, and then weigh the big picture accordingly.

[kfoote]

Why not a 20B 3-rotor? It's a direct drop in, they're relatively inexpensive, and it doesn't upset the weight balance of the car very much.

[MclarenF1]

I agree, that would be a heck of a motor. I've read alot about what a V8 switch would involve, but I haven't read much about the 3 rotor. Are you sure it's a direct drop in? That would definately be a better handler. The ultimate straight line capabilites of the V8 would probably be higher, though. I wonder how hard it is to actually get hold of one of the 3 rotors. And how rare are parts? I bet that would be an expensive switch...

[blight]

Originally Posted by MclarenF1

I agree, that would be a heck of a motor. I've read alot about what a V8 switch would involve, but I haven't read much about the 3 rotor. Are you sure it's a direct drop in? That would definately be a better handler. The ultimate straight line capabilites of the V8 would probably be higher, though. I wonder how hard it is to actually get hold of one of the 3 rotors. And how rare are parts? I bet that would be an expensive switch...

i am not worried about handling check out-
www.grannysspeedshop.com

they give all the info i need about the v8 swap. this is cheap.

and hey it onyl takes about 550hp to pull a 10 flat. Nice. So i think i am going to go with the sbc then in the RX. thanks all for the help on this.

[MclarenF1]

Sweeeet!

[blight]

Originally Posted by MclarenF1

Sweeeet!

i have been looking for 6 fucking years of obsessive compalsive hell - and now i finally found the perfect platform. I see you are new- if you really want to do everything this car is everything except mpg which is not so bad as it is. and hey you can do most all the types of racing depending on your suspension. autocross- drag- le mans style, even rally racing. this car really is the perfect platform. and hey it has a 50/50 weight distribution and has an ungodly low power to weight ratio as it is stock NA motor even. and not only that these cars can be easily picked up for under 1500 dallars i just bought one for 600 because it has no motor.

and one last thing- my girl friend thinks its pretty- and and there is enough room in the hatch area (if you move the seats forward and bend them forward as well) to mess around and do almost ALL the positions..--- he he he.. Thats right guys-

Anyway thanks all for your tremendous imput with this. see ya got to buy that kit for the fc now . OMG WEEEEEEEEEE! 150mph here i come (or cum which ever comes first- he the post could probably get me banned but i am so happy i could burst!)

[MclarenF1]

Friggin awsesome! Be sure and let us all know how it turns out. For the past 2 years I have known that I am definately going to build one for myself. I'll be done with grad school next spring, so hopefully I can get started the following summer. I even have my fiance excited about it. Granted, at first I had to bribe her (I told her if I could build this car, I would forgo buying a motorcycle ), but she seems pretty enthused about it now. She even brings me ads for nice used RXs! Anyway, GOOD LUCK!

[ls1mazda93rx7]

Originally Posted by kfoote

Why not a 20B 3-rotor? It's a direct drop in, they're relatively inexpensive, and it doesn't upset the weight balance of the car very much.

actually the 20b is very expensive http://www.pfsupercars.com/ any v8 would be cheaper. trust me ive been around rx7 for along time ive owned 3 different rx"s . the 20b set up i think weighs the same as the l-s1 counting all 20bs sub comp. do lots of thinking and research thats all im saying.

[blight]

Originally Posted by ls1mazda93rx7

actually the 20b is very expensive http://www.pfsupercars.com/ any v8 would be cheaper. trust me ive been around rx7 for along time ive owned 3 different rx"s . the 20b set up i think weighs the same as the l-s1 counting all 20bs sub comp. do lots of thinking and research thats all im saying.

i found out that with an iron block the 350 only weighs about 150 or so more than the rotary engine - with aluminum intake heads water pump and ect. i should be closer to 50/50 than the stock rotary so the guys with the rotarys fine great engine but shove it up your self when you want to argue about weight ratios. and that reminds me the power to weight ratio is closer than before when you add 150-300 horse to the what motor you already had so really now the carbed v8 is SO much better. Hmm i wonder when a mod is going to delete that post of mine...

Anyhow what kind of carb do you guys recomend for around town for better MPG for a 383 stroker anyhow?

[kfoote]

Originally Posted by ls1mazda93rx7

actually the 20b is very expensive http://www.pfsupercars.com/ any v8 would be cheaper. trust me ive been around rx7 for along time ive owned 3 different rx"s . the 20b set up i think weighs the same as the l-s1 counting all 20bs sub comp. do lots of thinking and research thats all im saying.

The 20B is about $4000 US for a new long block. The cost of the conversion parts should be less because a few of the same electronics can be used, and I believe the stock 20b engine mounts can be used. For the LS1 engine, it's $2800 for a remanufactured long block, a completely new wiring harness and electronics will have to be installed, you'll need a new transmission bell housing, new clutch, etc, etc, etc. The final price should end up about the same.

150 lbs may not seem like much, but when it's 150 lbs of weight that high and that far forwards, it is a big deal.

[blight]

Originally Posted by kfoote

The 20B is about $4000 US for a new long block. The cost of the conversion parts should be less because a few of the same electronics can be used, and I believe the stock 20b engine mounts can be used. For the LS1 engine, it's $2800 for a remanufactured long block, a completely new wiring harness and electronics will have to be installed, you'll need a new transmission bell housing, new clutch, etc, etc, etc. The final price should end up about the same.

150 lbs may not seem like much, but when it's 150 lbs of weight that high and that far forwards, it is a big deal.

hey moron read my post again IRON BLOCK- throw aluminum crap on it and throw the battery in the back and you are fine. and again 150-300 hp/torque- man give me friggin break you don't know what you are talking about it is way more worth than that rotary- and i have decidied on using a base 350 stroked out to a 383 stroker with carb, screw the ecu crap i have always worked with muscle cars and you know what so much easier and cheaper to get power - lt1 would be nice but you know what i am going to sell it and use one out of an old truck of a friends he is going to give the 350 to me for free - he ows me for some crap anyhow. so buddy don't even talk. check out v8rx7.com

[ls1mazda93rx7]

alright everybody settle down. v8 weighs 150lbs and the rotary tt rotary cant fuction with out all componets such as turbos, turbo manifold, intercooler, heatsheild, and all the rats nest of vacum hoses and pipes. all this shit weighs about 75-100lbs so u gain maybe 20lbs if you put an ls-1 so whats the point now. 20bs motors are really hard 2 fine parts for, and now you gotta find someone 2 work on an engine that 95% of united states has now idea what is. the ls-1 will get 32mpg on the hwy compared to the rotarys 24mpg.Im done with this thread, IMO id go with the motor in it or a v8.

[ls1mazda93rx7]

thanks everybody for the input, and im not cutting anyone down. c'mon blight why be so harsh on kfoote hes been a good sport and is just telling you his veiw of this thread.

[blight]

Originally Posted by ls1mazda93rx7

thanks everybody for the input, and im not cutting anyone down. c'mon blight why be so harsh on kfoote hes been a good sport and is just telling you his veiw of this thread.

Why? Because what he said was previosuly proven to be wrong in a post and the site that i had posted so it was worthless information. That need not be mentioned- in other words it is a waste of bandwith.