I have a really nice '91 RX7 with a 13b N/A Motor. I own a salvage yard so i have many parts at my dispense. I would like my rx7 to have around 400 whp. I currently have a complete 13BT Motor tranny harness and ECM. I also have a 99 camaro complete drivetrain. I cant decide wich motor to go with. My power to weight shouldnt be affected much by the ls1 since it is an alluminum block and 400 horsepower is very easy to get out of one. Ive been learning alot about rotaries lately and they really interest me. I guess what im asking is how hard is it to get 400 whp out of a 13bt. I guess also what would be the cost of getting 400whp out of a 13bt? In the end i want a reliable street car that can kick ***. Wich drive train should I go with?

 

In the long run the LS1 will be cheaper and most likely require less upkeep on your end. Also I'm in kansas just curious where abouts are you if I may?

 

Most FC's on this forum have a rotary engine... This is primarily a rotary forum, with plenty of rotary information.

Although the 13BT may cost more to reach your 400 HP goal... It is far more unique than an LS1.

 

I will definitely agree with the unique part. And I can't deny it's kind appealing just for the WTF factor even though my initial plan is the small block chevy route. Time will tell

 

I'd vote to keep the rotary too. I see to many people swapping in piston engines.
IMO, if you don't like the rotary engine, then why would did you purchase an RX car?

There are cars that look similar that can give you your 400HP and have piston engines for example a 951

 

By no means am I not a Rotary purist, but what's not unique about a swapped LS1?

 

k4 bro I feel ya there. I love RX's originally I had the spare 350 and already know how to work on them. Thus cheaper and a lot easier for me especially not having a garage to work in. But I love RX's specifically yea there are similar looking cars but they not the same. But now I'm leaning more towards the rotary for the sake of something unique. Plus I can always learn.

Off topic but my "new" Rex reminds me a little of my first car a '90 Chevy Beretta Indy. Never thought about it until tonight they kinda similar to gen 2's

 

Burnt you have valid argument but on the other hand how many cars are running LS1's? Not just RX's vs. how many cars are running rotarys?

 

The fact that the LS1 comes in MANY vehicles and is often swapped in many many more vehicles. Don't get me wrong... It's cheap for the horsepower. But the LS1 = generic.

Buy an 80-something Supra or Porsche 944 if you're looking for a piston car... Swap those cars, and leave the rotary to someone who cares.

 

Given you have access to both motors that takes a great deal of cost out of the equation. Comparing both motors, fully dressed, the ls1 is still ~60lbs heavier (I think it's actually 80 but it's been a while since I've looked at the numbers). I'm pretty sure the t56 or 4l60e (or whatever you end up using) is a heavier trans. than the t2 trans. Keep in mind you do move the weight forward and decentralize it with the ls1 swap. Even if you don't keep the motors fully dressed the advantage is still with the 13bt and it only gets more of one.

You'll have to either fabricate or buy mounts for the ls1. Depending on the trans you use you may not have to do anything but swap the motor, or just get an aftermarket driveshaft. Either way, at 400hp you'll need to look into an upgraded rearend for both scenarios so lets just say you got a t2 rear and swapped it as well, your driveshaft cost just went down.

From there it's a somewhat simple wiring job and then start modding for the 13bt. The mods will vary in expense depending on who you buy from. For the ls1, it's a more complex wiring job (or an expensive harness) followed by a couple somewhat expensive mods (it's an ls1, not a 5.0 or old 350) and you're at 400whp.

In the end I'd expect you to pay a bit more for the ls1 but it will be reliable (assuming no gremlins in the electronics) and you'll get 30mpg highway. I'd expect the 13bt to be ~200lbs lighter and need more consideration; no taking her for a spin and putting her away wet. That being said, I personally prefer boost to n/a. I'm putting an s5 into an fc that I picked up with a half done 350 swap in it. I'm doing it simply because I only want ~300whp and it's FAR cheaper to get that with a 13bt than an ls1, simply the swap costs too much to justify it (but it seems you don't have that problem).

Anywho, just my $0.02

edit: To add, you'll need to either fab or buy headers (not that cheap) and pretty much an entire exhaust system for the ls1.

 

I live in Junction city

 

fun fun. Off topic you see a lot of RX come through the yard? I'm out in Prairie Village/Overland Park. Wondering if it's worth the trip to the big one out here.

 

I have Two RX7s in my yard right now that have complete drivetrains. An 87 and a 90 vert both N/A. I also have an '83 12A motor in my wharehouse.

 

Well **** on that note I think I may be making a drive when the weather little better again. Prolly not to junction city though lol. Just my local.

 

I agree on the ls1.. Many cars run the ls1. The ls1 is a very dependable motor that makes great power. A set of ls6 heads and cams would easily make 450 at the crank.. I too am thinking of doing the same swap.

 

Agree with who?

Did you even read the great points that valley made??

 

if you have the LS1 already it would be easier to swap that in than to upgrade the 13BT.

if you had to buy the LS1 then i would say upgrade the 13BT as it would be CHEAPER, not more expensive as some claim.

 

I have been debating on the same thing and after weighing out the pros and cons and pricing I am sticking with the rotary. May start pulling it out the car next weekend and tearing it down hopefully everything is reusiable but with 0 compression in both housings something gave...

 

13b is the way to go lighter power to weight

 

Id go with the 13bt if I were you. Its a rotary powered car and there arent many of them on the road. There are a billion cars on the road powered by a v8 engine. The 13bt may come stock with lower power and only last until around 200k but it is definitely more unique then a v8. I also am in love with the rotary engine but go with whatever you want and Im sure youll be happy with either in the end.

 

LS1's always seem like a cheaper option in the beginning, until you realise your driving around 2 cars worth of parts.

If you know what your doing, LS1

If its your first swap, then keep it all in the family.

 

lol i've seen a lot of ls1 rx7s with nearly 50/50 weight, and the same total weight as a 13Bt powered car. that is assuming aluminum block and n/a on the ls1.

for the OP:

Both can cost the same or one can cost more than the other.
Both can weight the same with 50/50 weight
Both are easy to do if you read, and do it right the first time.
Rx-7s are great chassis regardless of the motor it's all in the build.

Just decide what you want to do with the car, decide how much money you want to spend, then double that cause you won't stop (trust me), and decide what you are more comfortable working with.

Both have there highpoints and both have there downsides. I have both and love both. don't give a **** if my car's soul is gone, as long as it's an RX-7

 

Keep it rotary. Love the 13bt. power to weight ratio is great and its unique. Had to get my input in so there. No Pistons!

 

port the 13B, add a single turbo set up, change injectors and add in some gadgets such as boost controller, fuel pump and regulator and a power fc.....you will get 400hp easily

 

LS1/3 would be cheaper. The latter you can hit 500hp with a cam and other minimal mods and will be 100x reliable than a rotary ever will be.

But seeing as you own a salvage yard, I guess its down to personal preference?