V-8 Weight nolonger a viable argument
 

Two companies are now building aluminum blocks that will reduce the weight of the cast iron 490 Lb small block Chevy to 390 Lbs.

Hekimian Racing makes a block that can be bored up to 455 Cid and all factory accessories bolt on for $4000.00

Chevrolet is producing the 5300 Vortec in aluminum for its line of 2004 vehicles
290 Hp @ 5200 & 325 Tq at 4000 with oil change scheduled at 10,000 mile intervals and first service at 100,000 miles.

Based on a rotary engine weight of 337Lbs:
The average battery weghs 30 to 50 Lbs, relocating it to the rear hatch, the weight on the front suspension will be increased :eek: by...10 to 30 Lbs.

How much do these engine's cost? Ten dollars says I can rebuild and port the hell out of a rotary for cheaper and get to 290 hp and 325 Tq.

Nice find though. 100lbs less on that block is pretty significant!

i doubt youll get 325 Tq outa a wankle with just 290 HP

No actually I would have much more HP!

But it would mainly be down low.

Re: V-8 Weight nolonger a viable argument
 

Is that based on shortblock weight or longblock weight? An '87 TII engine in shortblock form (no manifolds) weighs in at 200 lbs or thereabouts (according to the shippers who shipped me mine). I find it prett hard to believe that with 2 headers, 2 heads, and all other accessories it only weighs 60 lbs more than a 13bt

Being someone who has done a V8 conversion and also being someone who is running a website promoting the V8 RX-7 concept .... this is my opinion:

The newer Chevy LS1 is an all aluminum V8 (about 350-400 HP stock) and there is a couple of RX-7s that I know of that have LS1 motors in them. However, most of the arguments over RX-7 V8 conversions are from people who simply don't like the idea of anything other then a Rotary engine in a RX-7 so I suspect the arguments are not going to stop.

My biggest problems with the whole V8 RX-7 concept is I don't like referring people to Grannys Speed Shop for the V8 conversion parts because I hear a lot of horror stories about Grannys and their products (I also had problems with Grannys).

<~~~ doesnt like v8 swaps ... its kinda like ruining the heritage of the RX series..... and all that time those people in japan did the research for years to get it to work... same with the germans.... to me it feels like your disgracing the cars soul.... oh well thats my opinion

<--------- hates v8 swaps also


-Shawn (v8 swaps are for people who are scared of the big wankle)

If you move the battery to the rear of the car how is wieght increased on the front end?

Ah heck. To each there own. I am drawn to the RX-7 for it being unique. And I would have to say a RX-7 with a V8 is unique. At least if you do the swap you know they are automotive enthusiats. Which is more than I can say for some of the wankel engined rx-7 owners i have meet.

James

"Almost immediately after taking over the RX-7 program, Kobayakawa began work on the next generation. And while there was total freedom over the powerplant choice for the new sports car, the rotary was selected, first for compactness and power potential, but also for heritage. Said Yamamoto: "To forsake the rotary would be losing our identity. The RX-7 could not and would not exist without the rotary"

hmm...

The new posts........ support my point above. ;)

im only gonna post once here because i have had this argument so many times before.

V8 RX-7's are an issue that will never have a one-sided argument. personally I would only convert a Vert to a V8 (mainly due to the fact that it is a heavy beast), but V8 Rx7's are just as fast, unique, and time consuming as the regular. the rotary will never die or go away completely and there are many many people who love the rotary, so we dont need to worry about rx-7's becoming extinct or all v8's.

i guess i feel this way because i have 3 7's and when you have had your fun with the wankel, a V8 rx-7 is quite intruiging. i think rotarists should be honored that the Rx-7 is the subject of many V8 swaps. it proves that, not only is the rotary engine a work of genius but the car it primarily resides in is a piece of genius as well

Justin

YA CHevys LS1s suck ass! I HAD a Camaro Z28 with a LS1 and it could not even pull a full car length on my friends NA 91 RX7. Not to mention GMs usuall problems with their electronics. The six speed was ok but the skip shift was annoying as hell. Also 290 HP from a big ass V-8 is horse shit. Piss poor performance and I would expexct nothing less from GM but piss poor performance. Ok lets see Honda has 2.0 NA thats putting out 240 HP and now Mazdas RX8 will be putting out 250 HP N/A so what the hell GMs got all those cubes to play with and the best they can do in stock trim is 290 LOL Man that is funny. I got a idea GM should just close up shop and do the whole world a favor by not selling there crap products anymore. Oh ya where is 1/2 there motors assembled now? Mexico and the other 1/2 Canada. Not only do they rip the American public off by selling junk cars to the working man but they fire a good chunk of them and move assembly plants to Mexico for cheap labor. Yet the cost of labor goes down but the price of the car still goes up, plus the cost of ownership goes up because of high maintenece on their junk products. Ya know when I think of high quality products and especially cars and where they are made for some reason Mexico does not pop into my head. I guees when I think of high quality craftsmanship I think Japan, U.S. and then Germany. So take your low tech aluminum cast blocked V-8s and throw em in some Impallas and sell it in Mexico. We dont want your crap and you won't sell shit. Imagine a 5 liter rotary? It would mop your V-8 shit up right now. DUMB ASS. Please sombody quote me I love that shit :)

Funny you should mention problems with electronics. Does ANYONE have a wiper switch that works right? ;)

Also let us not forget that that 290lbs is backed with a large 350+ ft lbs of torque that will get your car moving ina hurry.

PS If a LS1 Camaro pulled on a 91 N/A, that Camaro must have had both head gaskets blown, dropped 2 pistons, and have 2 flat tires.

Either that or you are full of something. BS meter anyone?

A LS1 6spd Fbody should be a VERY low 13sec car. If you can't pull a NA RX7 with 160hp, you can't drive. I like V8 RX7's, when my motor pops (and thats not IF but most certainly WHEN) I will seriously consider an LS1 swap.

Daniel

Weight.
 

I'm actually still curious about the weight of a longblock V8 compared to a longblock 7. When I say longblock I mean a totally stock TII with emissions control, compared to an aluminum block with heads, emissions and headers. I'm not bagging on anybody or their projects/cars, I'm just curious.

-David Guy
Andern Research Labs, LLC.
dguy@andern.org

Yep....you are a dumbass. LS1's suck???? are you on crack? Ls1's in the new vette make OVER 400 HP. YES repeat that with me again.... 400 HORSEPOWER. That is nothing to laugh at. I would also like to see this 240 hp honda engine produce more then 200 ft/lbs of torque that you are talking about. And whats this about you couldnt pull on a Na rx7??? you know there is more then 2 gears in a 6 speed right? Your whole post just proves your stupidity.... here you go. this should be good enough for now.:wtf1:

-Jerry

Mine works just fine :confused: LS6.

does it seem to anyone else that the Marines are an angry bunch of folks.....what was it my dad used to say... Utah State Motorcycle Club??? Uncle Sams Misguided Children???

Justin

what about weight split???

With the V8, 80 percent of the weight is above the crank as opposed to the rotary which is closer to only sixty percent above the crank.

so all you V8 advicates, how do you compinsate for the change in center of gravity???

Even if you add/replace all the extra parts to make the V8 light enough that it changes the weight to maginally close, what to you do about the center of gravity shift???

Or again is straight line drag performace the only thing V8 conversion people are intrested in???

I have a 5.0 RX, it was either that or it was going to the crusher, so sue me.

Tell me again why I need all that torque to move a sub 2800lb car?

One thing to keep in mind about stock (from the factory) horsepower ratings... They don't mean squat. Does anyone care that a stock Camaro makes xxx hp? or a stock RX7 makes xxx hp? Yeah, maybe the first week you own it. My point is this: Everyone who buys their cars for performance reasons, always has the next mod in mind -- and more often than not, that mod is a HP mod...

Keep in mind that the factories crank out passenger cars to be basically on similar levels of performance -- I mean within the same class of car. The factory does not build a motor to it's potential. I don't care if it's Chrysler, GM, Honda, or Mazda. They build it to a level of what they see as extreme reliability, some degree of efficency (MPG), while still maintaining somewhat of a performance edge on their competitor(s).

So to compare a 2.0 Honda to a 350 GM while both make the same horsepower doesn't really mean much... I applaud Honda for getting the same results from a smaller package. But keep in mind there are people who would own nothing less than a V8 in a domestic car. (Including me except for my FC). It's all about marketing . . . Remember back to the 60s when motors were cranking out 400 HP STOCK, and the factories were CONSERVATIVE with their HP ratings -- read: they made more than advertised! Why? Marketing strategies...

If we saw factories build to the limits of their engines, there would be no fun for us. We wouldn't be able to mod without seriously comprimising the reliability of the engine -- and most of our results would probably result in very small improvements.

Sorry for the longwinded post, but my point was that comparing stock ratings doesn't really mean much to most enthusiasts because of what we have planned for the car. Although I have seen some extremely powerful small displacement motors, there is no denying the Torque and HP potential of bigger displacement engines. Right now, those bigger displacement engines are piston engines. I'll freak (and applaud) the day I see a small displacement Honda or Mazda (or anything) run the quarter in 4 seconds... I'm not saying it won't happen, but based on today's technology, it's not possible (or at least no one has figured it out).

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 :rolleyes:

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.

:eek:

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 ...... :rolleyes:

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. :rolleyes:

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.:D

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 ass....I think the point has been proven that even in stock a Camaro will kick the shit 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 :puke: on the spot.

http://image1ex.villagephotos.com/pu...sp?id_=1195328