A 20B takes more cooling so it's going to need a larger radiator and larger oil coolers. More fuel, more plumbing, more wiring, etc...
In turn it's going to need larger wheels and wider tires to handle the additional torque, larger heavier brakes to to slow the extra power and weight down.

All of this doesn't just add a few pounds.

 

^ True but some of these upgrades can and should be a part of a 500hp 13b car as well. When they are close in weight even with 20b car hauling what extra weight it has to have I'd still be putting my money on the 500hp 20b car to pull on the 500hp 13b car. But just for good measure lets just do some weight reduction to the 20b car to bring them back to dead even weight.

 

Perfect example of 20b reliability/durability. Attila the Fun just recently rebuilt his 20b. When he did his conversion a few years back, it was a stock rebuild done by Peter Farell (no special seals, coatings, porting or nothing). The engine made over 350rwhp and over 400lbs at 15psi on stock twins. The engine lasted over 70k miles with the owner running the engine fairly hard that entire time. The engine could have lasted longer than that given the condition of the internal parts. When the engine was pulled apart by Kevin Landers (Rotary resurrection) said the internals were nearly perfect. I can't remember what caused the engine to blow. Anyways, Glassman man, I challenge you to find any 13b that would have lasted as long as this 20b did at that boost level, while also being abused making that kind of power for 70k+ thousand miles. I seriously doubt you would find that unless the 13b was always granny driven.

Here's some more facts for you. The larger displacement 20b wont need to rev nearly as high as a 13b to have decent acceleration. All that high reving does is shorten your engine life. The less you have to push your engine, the longer it will last. The 20b will have more power thoughout the entire rpm range. You can take a corner at 12mph while the gear selector is in 4th with a 20b. Don't even think about doing the same thing with any 13b.

The only downsides I see to the 20b is the extra cost, slightly heavier weight, and worse fuel economy.

 

3-rotor = use S5 NA high comp rotors All 20B's were TT out of the factory. How can it be deemed reliable? We all know that turbo charged cars are shitty. Go NA fashion if you want a race car. For *****'n'giggles do the Cosmo 20B TT. Yes, RE's are durable. You can push them to hell.

 

yeah the stock twins seem kinda dumb, especially when they weigh in at over 80lbs with the cast iron exhaust mani. Go big single, or n/a like I did!

 

In my opinion (dont take me literal b/c I havent done a 20b swap only a 13B-RE swap which is still in progress.) So far they seem like they would cost about the same. I had to get better brakes, a front mount, the engine, a new radiator, the mounts (both the 20b and the 13bre uses the same mount kit to bolt into an FC,) a EMS, a new drivetrain (tranny, diff, axles, etc,) blowoff valve all of the hoses, the downpipe, a high flow cat, exhaust, etc. To me, from the 20B conversions that I have seen and the 13B-RE conversions that I'm undergoing right now (yes that means multiple) the only major price difference between the motors seems to be the motor.

The 20B will cost you $4k by itself whereas you can get a 13B-RE for about $1.5-2.5K. Whenever people talk about these swaps, they always talk about the prices to support the new engine (like cooling, EMS, etc.) But when you think about it, you would have to do the same for any other car that's making such high hp numbers. I am not trying to join any ongoing arguments... Only tring to give my 2 cents on the matter.

 

When I weighed just the iron bits; the manifold, twins in their housing, and the short down pipe, all together they weighed 62lbs. Yeesh.

 

 

I'm actually working on a 20b FC swap right now. I found my 20b on Ebay for $3,800.00 shipped. This included the Engine, Turbos, ECU, Wiring Harness, and Transmission. In my opinion this is a very decent price. The only issue I had with the engine upon delivery is that the upper intake manifold was cracked, and the waste gates were damaged. Although those will no longer be an issue as I'm converting to a single turbo and going to build a new intake manifold for the car.

The goal for the 20b is 600 rwhp, which isn't a big deal, just something to have fun with. We're going to be using probably a T-88 turbo (incase we want to add more power later down the road. I'm very fortunete as I have a shop that allows me to come in during the week to work on my motor and car. The biggest costs in this build for me is going to be Turbo, Brake system, Suspension setup, and a few other odds and ends.

Here's prices so far for my FC build

88 FC3S - S4 - N/A - $700.00
Complete 20b 3 Rotor Engine - $3,800.00 shipped
RE-Amemiya GT Wide Body Kit - $7,000.00 (only one in U.S.A. WOOHOO!)
Tein Flex Coilover System - $1,300.00
Tein EDFC Controller - $300.00
5 Lug Conversion - $200.00
Other odds and ends - $500.00

So depending on what you want the end result to be, prices will vary. I'm probably looking close to about 40k to 50k for my entire project. But a 20b is capable of a lot more power/torq then a 13b and will have to work less to make that same power. To put it in very simple terms, compare a 500 whp Civic to a 500 whp Mustang.

Blackbird

 

^ Don't forget the turbo II tranny and rear end.

 

Actually Sean wants to use the 20b transmission. Of course it will be moddified, and we may end up using a 9 inch Ford rear. We have to take things apart and see what we have to work with. I'll try to keep you updated as possible.

Blackbird

 

The 20B install wouldnt be as much for others as you though. For example you are including your 7k body kit...which wouldnt be included in the cost of the swap.

If I wanted a monster street car I would go with a 20B....if I wanted something to have fun with on a drag strip only I would just build a 13B. Major HP out of it, save the money from not having to buy a 20B and have it shipped. People have said a P-Port 13B built up will only last 10-50k miles...true. But at 1/4 mile at a time...how long would it take to reach that mileage. Yes it would break something from the harsh driving...but ANY drag car will break.

I know a few people will bash me for talking about dragging, and say its not real racing or whatever. Im just making a point...and if you bring up something like "well how long will the built 13B last on a road course...something more than 1/4 mile at a time", well all I have to say is you dont need that kinda horsepower on a road course. Not like you can use all of that power in a curve. Im sure the 800hp in a mid 2k lb car will really stick to the road when you gun it.

 

Thanks for pointing that out, it's true not everyone will spend 7k on a body kit. I was just putting prices out there so they would have a general idea of costs. Redneck is right though, if you build a 13b with a P-Port you can get major numbers out of them. They don't last very long, but don't cost nearly as much to repair when they blow up. And if anyone ever tells you otherwise you know they are full of ****. Any motor built for racing, I don't care if Pettit, Acosta, or Amemiya built the motor, sooner or later it will break. 20b's however will maybe last you a little longer depending on power you want to make. To give you an example take a 13b @ 600 hp will maybe last you 50K or so (don't know exact numbers) now a 20b @ 600 hp will last you probably 75K (this of course is based off the fact that you have 1 more rotor helping to do the work of the original 2 rotors.)

Now costs of a 600 hp 13b, and a 600 hp 20b will vary. 13b will cost maybe 10-15k. 20b will cost 20-25K because you have more parts to deal with and different tuning is involved. I'm not sure on exact prices, these are just general prices I'm throwing out to show the difference. If anyone can help back this info up that'd be great, thanks.

Blackbird

 

Please lets not quote these kinds of pricing estimates based on engine choices. As far as the engines themselves, both engines will need enough turbo and fuel to reach those levels. The 20b will only need additional dowel pinning to run safely at that power level without twisting the block. You don't have to spend 20-25k to have a 600hp 20b.

 

You may not need 20k to get 600hp out of a 20B, but he was probably including the cost of getting a 20B and swaping it. So technically it really would cost that much to have a 600hp 20B in your car.

 

yes, that was including the buying the engine, and putting it in the car. As well as cost for tuning the engine, that's not cheap. But if you actually break down parts and prices of building a 600 hp 20b I'm sure you'd get close 20k

20b block
20b rebuild kit
dowling
turbo
fuel system
ECU & tuning
installation of parts

Also I'm giving prices that it would probably cost if a shop did all the work for you. If you did all the work yourself yes it would be cheaper. Also I'm not trying to scare people away from doing swaps by qouting prices I'm just trying to cover the full spectrum in what it takes to build a solid running engine.

Blackbird

 

Actually if your just talking about the engine upgrade 20k is still high. You can have a 20b in an Rx7 and running with good power for around 10k and even cheaper if it's in an FC(as some forum members have proved). A Gt-42r and manifold would add an additional 3k w/tuning. Now of course these prices are if your able to do most of the conversion yourself saving labor. Currently I'm rebuilding my own 20b engine and have spent less than $500.00 just the rebuild the block (that includes new RA seals). You just have to know how to shop.

Stock engine 4000.00
Rebuild 500.00
Doweling 700.00
Flywheel 220.00
Stage 3 clutch 450.00
Subframe 1000.00
Ecu 1500.00
2 Walbros 200.00
PFR 200.00
Exhaust 1000.00
rad 500.00
IC 500.00

Thats less than $11,000

Keep in mind some things will be higher or less depending on what you use and if you want to use new housings and such (which in most cases will be a waiste of money since the used blocks are usually very low mileage). Some people think everything has to be brand new! Nope even the stock block engine will make that power with stock original internals and only dowel pinning. Durability is all based on how well it's tuned.

 

were all 20b automatic trans??

 

Yes.

 

No I am talking about a 20b, that has been dowelled, street ported, solid corner seals, upgraded fuel injectors, new fuel pumps, ECU, GT35R turbo, fabrication of turbo manifold, fabricated intercooler piping, fuel cell. The prices I'm qouting are something a shop would charge you, not if you were to do the work yourself. I want something capable of 10 seconds or less in the 1/4 and still completely streetable, with a full interior. I'm a firm believer in "going fast & looking good!" Damn perfectionist complex!

Blackbird

 

I see what your saying however, Gt-35r isn't enough turbo to reach your 1/4 goals unless you do some weight reduction. You could hit the high 10's but not lower than that. Personally that's the turbo I'm gonna use on my 20b because I want the response and a broad power band. 450max rwhp would be more than enough for me on the street.

 

Some minor corrections/additions:

368 rwhp and 425 lbs/ft torque at the rear wheels

Cause of engine failure: the nut behind the wheel. I was driving late at night in January (cold weather = leaner mix) and did not react quickly enough (due to being sleepy) to the sound of pre-detonation. No blame can be assigned to the engine or the builder/tuner.

3rd gen drivers who have driven my car have commented that it isn't working nearly as hard to accomplish the same thing, which supports t-von's comment about "won't need to rev as high".

The short answer, though, is torque. No matter what you do to a 13B, you won't get the kind of torque the 20B produces.

 

I have a 1990 rx thats i have awaiting "maybe" a 13bt swap, but recently i read an artcle about a rx with a 20b and it rekindled my intrest in doing a 3rotor FC. now i dont need to run the **** out of my motor, im not racing. but an ocassional session in an empty parking lot or well known turns would be inline but basically just as a daily driver but only like 80 miles a week running like 10psi of boost and the normal assortment of goodies to keep it running cool temps, what kind of reliability and power compared to a 13bt would i be getting? and also if i did run a 20b i could use a 13bt tranny? and what else would i need compared to a 13bt swap to run a 20b

 

Honestly, I think the 3 rotor comes down to: if you can afford it or not.

 

For my project comming next spring time, Im going with a bridgeport 13b n/a instead of a 20b.

For one, its cheaper, WAY cheaper to build it, and rebuild it.
And two, its going to be my weekend driver anyways so thats about a rebuild every 2-3 years or so