How fast do you want to get to 60mph?
How high do you want to pull the wheels in the air on a 1/4 launch?
Do you want to drift?


All of these require torque baby..
Some people just want more than what they have now...

 

That was a good point about the weight being higher up on a V8. That has gotta have an effect. But how would you measure that?

James

 

My stock TII gets to 60mph plenty fine for me. Plus most of my races start around 80-90mph. I don't care about putting my wheels in the air and no I do not want to drift (because I don't feel like wrecking my TII).

So again, tell my why I need all that torque from a V8? I find the torque I get from my TII more than satisfying.

 

Hate to tell you, but 2800lbs is still a whole lot of weight that will need torque to move.

Why is there this urban myth that when a car gets around 2500lbs it seems to magically be light as a feather and physics no longer apply to it?

 

Well I tell you what then. You've convinced me. I'm gonna throw out my turbo rotary engine for a turbo diesel. With all that torque I'm sure to run 9's and turn record times at Mid Ohio

 

The question about center of gravity is easily solved. The kits sold to put a V-8 into a RX-7 lower the engine and move it further back, thus correcting the weight distribution and the center of gravity. Not something I would ever do myself but whatever makes you happy.

 

See that's the wonderful thing about torque. It can be manipulated through gearing.

Let us also not forget the horsepower is derived from torque and engine rpm.


HP = Torque * RPM / 5252

More torque means more power, plain and simple.


Read up on the difference between Torque and RPM and you will find out that Torque is what gets the car moving.


Simple case, even in RX7's its true. The car pulls harder at the torque peak, not the horsepower peak.

Torque is also wonderful because you can manipulate how much FORCE is going to the wheels, although the POWER at the wheels is unchanged, no matter the gearing.

 

i'm sure anyone driving an rx7 would notice the power difference if the car had a v8 in it, but how many 2nd gen owners drive their cars hard enough to notice the difference in the handling that would be created by a v8 swap? most of these cars are driven on the street and will never use the handling potential that they were born with. slap on some higher performance suspension pieces to compensate the v8 and half of the rx7 drivers out there probably wouldn't be aware of any handling difference.

hmm i wonder if anyones ever put a hemi in an rx7, that truly would be a unique car .

and im just curious, but does anyone know the weight on a built 20b tt block setup?

 

A V8 conversion is for people that want to go fast with less money. I do however agree that it does some what disgraces the RX-7's name, but that doesn't mean I wouldn't do it. I want to put a LS-1 in a Honda, for sleeper value and sheer enjoyment.

 

I agree bingoboy, I think the handling issue is pretty well moot because the argument seems to center around the drag strip.

Xtream, also a good point. Personally its my beleif that unless it has a 13B in it, it's no longer an RX7. (when referring to 2nd gens anyway)

 

i believe the V8 swap shouldnt be thought of as a matter of weight, but as a matter of where the weight is placed, the V8 engine will overhang further than the rotary engine by a good deal, therefore not making the RX-7 a mid engined car any more correct? therefore the inertia, and handling characteristics of the car will be ruined. it isnt the weight of the rotary that is so amazing, its just how short the block is that makes it amazing

 

LS1 is shorter, sits lower, and weighs less than a dressed 20B, so for all the reasons you all say the LS1 is bad (logical reasons anyway), the 20B is worse. And it even costs more, and with the LS1 you get more reliabilty, more potential for power, and a 6speed.



I looked up the weights of a dressed 13BREW and an LS1 longblock just to prove someone wrong once, as I recall the LS1 was only about 10lbs heavier. Cast iron turbo manifolds and turbos aren't light.

I am not going to argue which is better, because frankly I don't care. It all depends on what you want. If you are tired of swapping 13BT's into your car on a regular basis, and you want torque, then you may put X kind of different motor in you car. However, some people are fascinated with the rotary and won't have anything but one, and good for them, but thats still not a reason to be blind to logic.

Just remember, Torque wins races and horsepower sells cars. Those races which occure in a reasonably straight line anyway

 

everyone has had good points. i'm one who believes that it just doesn't seem like a 7 w/o a rotary since that is what drew most of us to these cars. it sort of turns into a frankencar. also icemark hit it on the head for those of us into the dynamics the compact rotary offers. low center of gravity and a midship package. even with battery relocation, you have added front weight out further and up higher. raising roll centers affects a cars handling immensely. as for turbos, yes they weigh more but you can also keep that weight back and low with proper engineering and just the general fitment of a turbo. thus advantagous packaging ability. to each his own, though.

 

They may have the weight down, but the size of the block is still the same. Therefore, it still won't be able to be put aft of the front axle line, and the weight distribution problem is still not solved. 20b's only came in luxury Cosmos where Mazda didn't make weight dist. a high priority. Ie. there is no reason to compare the location of a V8 in relation to a 20b in an FC. If you can get the weight dist. equal to a 13b, then you may convert some nay-sayers.

 

Mr. Eccentric,

Well in your eyes then a LS1 swap must be superior to a 20B swap, because the 20B is even FARTHER out over the front axels. There is no reason to compare a 13B to a LS1, the 20B is the comparison since we are talking 2 powerplants that can compete with one another.

Daniel

 

I think this is called grabbing at straws.... great to sit back and watch the inane discussions about center of gravity, weight issues, engine placement and anything anyone else can think of to keep this discussion valid! These are all opinions (that I respect) of people who have no clue what 500ft lbs of torque will do to a 2900# car with 4.10 gears.

 

Ok. Rotaries have a much higher redline potential then any piston engine ever will. one point made. What compression is your V 8 running? probably higher then 9.5. Sure it takes more money to get a rotary more HP and torque becuase alot of stuff needs to be custom made. But quite frankly.. it is my beleif that once you swap an american engine into a import car that car is not longer an import for it's heart and soul are ripped from it. And only import cars can do that 2 grand per race thing around here.. not to mention when people hear a 7 they know whether it's a rotary engine or not by the simple fact it's exhuast sounds alot like a moped engine that's about to blow screaming through it's exhuast. Also not to mention someone got 498 pounds of torque and 517 HP at the rear wheels with a 13 B-REW and he pulled his wheels more then high enough for me. one i don't like having my front wheels in the air.. it's not a good thing on cornering courses Yeah sure it's cool to see, but i also like keeping tires on my car when racing. I have lot's of plans for my little 1.3 liter rotary.. but like alot of things it takes time.

 

I rest my case ......

 

Some people don't care about their cars "soul"...
some people just want to go fast. Who doesn't?

 

That is the dumbest most uneducated thing I have ever heard. If torque was all that mattered then we'd all be running diesel engines.

Why would you want a torquey V8 that can't rev? I've never heard of a V8 revving to 9 grand. And if you did want the power of a V8 then just buy a car with the V8 already in it and leave RX-7s to people who actually love and respect the car.

 

Read the whole thread before commenting. See above where I mentioned that the kit from granny's takes the block and moves it lower and further back, offsetting the issues presented by the V-8 block.

Ben

 

Yeah that's great, but even with relocation a V8 is a long engine, you may be able to get the CG even lower than the rotary somehow, but you won't be able to push the V8 back far enough unless you cut the firewall out and then you have more problems from doing that.

BlackFC
I was never condoning a 20b swap at all. I have no interest in putting a 20b in my FC. The 20b is a compromise in a front engine car such as the FC. You'd need to have a mid engine rear drive set up to realize the chassis potential from the engine's. Same for the V8. Period.

If all you want is torque and straight line speed than a V8 is the way to go. The by-product though is an Rx-7 with an identity crisis. Just go put a V8 in a Chevette instead, save the Rx-7's for those who have an appreciation for the pure engineering marvels that they are.

Hang on while I put on my flame suit.

 

Holy crap this thread is funny to follow....

"Rotaries have a much higher redline potential then any piston engine ever will."

ROTFLMAO...

BMW Williams F1... maybe some of you should petition that they switch from piston to rotary...

Facts & Figures:

Number of combustions during an average GP: 8 million
Maximum rpm: 19,000+

With three rotors...

13G, 20B, etc. all under 12,000 rpm

I'm not a rotary purist or anti this or that I love cars period. I find merit in almost any form of transportation and their respective shape, purpose, design, etc. When I see people on here with names like "V8sAreSlow" I think to myself wow... close minded. I remember standing in pit lane at MIS and you could hear the CART cars rolling through the speed traps at 256 mph at the end of the back straight. All vehicles are special, all deserve respect, some more then others, to not find someone's vehicle attractive or unique or the fact they embrace the automotive culture in some way is immature in my estimation.

 

Trav-
I definitely hear that...Does anyone here remeber when there were cars roling off the showroom floor that did the 1/4 in close to, or les than (not really sure of the exact numbers) 11secs?
Anyway....about the Chevy LS1 sucking ***....I think the point has been proven that even in stock a Camaro will kick the **** out of a lot of other cars...a NA 91 RX7?












Thats not even a contest.

 

I think the most bizarre trend in F1 was the turbo days, BMW had that 1.5L block that started life in an equivalent of what would now be a 3 series, producing 1200+ Hp by the end of development.

Don't get me wrong, I like V8's indeed, it's just I don't see them having any business in anything with 'Rx' for badging. Strike that, keep 'em out of R100's REPU's and if I ever saw a Cosmo Sport with one in it, I think I'd on the spot.