RX-7.... Rotary vs V8

[upgtx]

If you want a turn key 300rwhp turbo II and you can find the car, AND money is not too much of a factor.

Find the car, buy it, and bring it here.

Down to mankato, talk to Jon Wehner, he will put a v8 in it (has done two already) and you will have 295hp (minimum), a six speed and mid-high 20's mpg on the freeway, you will run mid 13's MINIMUM, and you will never have to worry about blowing an apex seal.

 

[RockLobster]

Down to mankato, talk to Jon Wehner, he will put a v8 in it (has done two already) and you will have 295hp (minimum), a six speed and mid-high 20's mpg on the freeway, you will run mid 13's MINIMUM, and you will never have to worry about blowing an apex seal.

Interesting my car has ALL the same qualities with a rotary in it, including not worring about blowing apex seals.

Plus it weighs about 200lbs less....

EDIT: 100-200 lbs less depending on which V8 it is...

 

[upgtx]

Turbo II's weigh less with an LS1 in them than with the stock motor. Yours is an FD though, so that doesn't really matter. One thing your car is missing though is TORQUE.

You can't really argue the cost of keeping the rotary reliable against the cost of keeping an ls1 reliable... In general turbo rotaries are not very reliable.

 

[mndsm]

Ah, no. IIRC the car is an FC. Nice one too.

 

[upgtx]

Well, his weight numbers are way off... Lots of people have LOST weight overall from the 13b to the ls1...

http://www.hinsonsupercars.com/faqFC.htm

http://www.rx7club.com/showthread.php?t=44799

http://www.rx7club.com/showthread.php?t=198154

 

[spek1098]

Yea, it be a bit easier to squeeze more power out of that ls1 then any rotorary. In fact, fd/ls1's have the best power to weight ratios of any cars I've seen out there. I kinda hate v8s, but wow, what a combo...

 

[RockLobster]

In general it is easier (read cheaper and requires less engineering) to get high power out of an LSx engine that is true.

But the weight numbers are incorrect. I have personally weight LSx powerd FCs and they are all else being equal a minimum of 100 lbs heavier.

The reason some people claim otherwise is that they either remove things like AC and make other weight reductions. Also the people that sell the conversion kits are doing just that, trying to sell conversion kits.

So unless you have delt with both setups

For instance a guy who lives in farmington just did and LS2 conversion.

My car is almost completly stock including has A/C and power steering still. The only weight reduction i have is my ABS is removed.

Both are S5 cars and his is about 120 heavier. Further, he has other weight reductions. I have dual exhaust still, he has single exhaust.

Thus typically the "weight savings" of an LSx motor is due to other weight reductions.

 

[upgtx]

The second link I posted was a guy who JUST got off the scales... And, I have seen IN PERSON 2 fc's with v8 swaps that weighed less than stock without weight reductions made to them. One big determiner is the tranny though, if you use the 6spd manual you generally lose weight with when compared to a stock turboII, I posted links so far proving I am right, post links proving me wrong.

 

[RockLobster]

Turbo II's weigh less with an LS1 in them than with the stock motor. Yours is an FD though, so that doesn't really matter. One thing your car is missing though is TORQUE.

You can't really argue the cost of keeping the rotary reliable against the cost of keeping an ls1 reliable... In general turbo rotaries are not very reliable.

Yes the car is an FC. And i will agree pistions will always have the torque advantage. But NOT the weight advantage. Block for block the 13b is lighter.

Also quite simply the reason rotaries have the reputation they do is simple.

Rotaries dont tolerate stupidity. That is why it is far easier to create power with an LSx motor. Some people just dont have the patience or understanding to set up, tune, and properly maintain rotary engines. They do not tolerate poor tuning, or lack of maintenance.

So yes it is easier to make reliable power with an LSx motor, because the LSx motors are far more idiot proof.

But, if you know how you can have a powerplant that is just as reliable in a rotary.

Plus i would love to see someone continually take an LSx motor that is mostly stock take it 1000rpm past redline contiualy and have it hold togeather for as long as a rotary will.

 

[RockLobster]

The second link I posted was a guy who JUST got off the scales... And, I have seen IN PERSON 2 fc's with v8 swaps that weighed less than stock without weight reductions made to them. One big determiner is the tranny though, if you use the 6spd manual you generally lose weight with when compared to a stock turboII, I posted links so far proving I am right, post links proving me wrong.

Because everything you read on the web is right huh.....

 

[RockLobster]

For instance a guy who lives in farmington just did and LS2 conversion.

My car is almost completly stock including has A/C and power steering still. The only weight reduction i have is my ABS is removed.

Both are S5 cars and his is about 120 heavier. Further, he has other weight reductions. I have dual exhaust still, he has single exhaust.

Thus typically the "weight savings" of an LSx motor is due to other weight reductions.

This car has a t56 transmission, and is still heavier.

 

[spek1098]

Because everything you read on the web is right huh.....

I think your forgetting the stuff your typing is on the web...

He's listing references to back up his argument, that is just sound debating. Please give us some references to back up your argument, otherwise its just your word, on the web.

 

[RockLobster]

I think your forgetting the stuff your typing is on the web...

He's listing references to back up his argument, that is just sound debating. Please give us some references to back up your argument, otherwise its just your word, on the web.

Does he or do you own any of these cars?

Lets forget the web, how about i host a tech day and i will SHOW you on my intercomp scales to prove it to you....

That way nobody is using hersay from vendors who may or may not include bias to sell thier products.

I would submit that using potentially heavily biased sources for reference is hardly sound debate method.

To perhaps bring a petty argument to a close, ill conceede that both engine transmission assemblies are close enough in weight (assuming one of the full aluminum LSx) blocks that weight reductions in either seupt can tip the scales either way.

 

[RockLobster]

Well, his weight numbers are way off... Lots of people have LOST weight overall from the 13b to the ls1...

http://www.hinsonsupercars.com/faqFC.htm

http://www.rx7club.com/showthread.php?t=44799

http://www.rx7club.com/showthread.php?t=198154

But to play the game a little longer

2nd reference refers to weighing a v8 car vs mazda curb weight published numbers from 15+ years ago which are known high numbers. For instance my car BONE STOCK was 100lbs ligher than mazda published curb weight for my model/trim...

Further his weighing shows it to be 123 lbs heavier than the factory published curb weight.

The third reference is an actual admission that his car is slightly heavier. I have read probably upwords of 20 threads just like those two, all are only proclaiming 1 thing. The swap isnt as bad with an LSx motor as with other v8s like a standard small block. But it is still heaver by 100lbs or more...

 

[mndsm]

I have to say I take the side of RockLobster on this one, I have a hard time believing a Chev smallblock would EVER weigh less than a 1.3 rotary. Also, he's more than willing to prove it, offering scales and the works. That being said, let's try to keep this friendly. I'm a fan of both ideas myself, and no matter what happens, the car is going to be fun to drive.

 

[RockLobster]

I should say that as well. I like the LSx powerplants a lot I am actually on the hunt for a nice vert with a blown motor to put an LS2 t56 combo out of a 05 or 06 gto into for a street sleeper.

But for the track i would rather have my rotary....

 

[spek1098]

Does he or do you own any of these cars?

I don't think that really matters, do I have to go to China to know that it exists?

I don't think I've claimed to have any perticular knowledge of this car, I've only stated general observations of the statements made in this thread.

That being said, if everything you said here is true, and its 100lbs heavy then stated, this whole arguement is kind of mute anyway. 100lbs isn't very much, its the difference between a skinny 5'6" guy and a normally build 6'4" guy. Also, to over come the diffentcy that the 100lbs will make in the over all power/weight ratio would be very easy with an LS. Say the car is 2300lbs stock (a guestimation) with 300 hp thats a ratio of 7.666. So the ratio in a LS fc, weighing 2400lbs with 300 hp, is 8. You would only need 15 more hp to have a 7.666 ratio in the 2400 car.

Now I'm not dissing your setup, as you say, its hard to build one of these that will hold up in the long run, and if you've done it as you say, then props, that's a bit harder that dropping a V8 in there.

 

[mndsm]

I've seen his car dyno. On a rough tune with low boost (breakin) It hit something close to 250 to the wheels on LSE's dyno. I'd say 300 easy out of that thing, and it ran like butter.

 

[mazdamn02]

I don't think that really matters, do I have to go to China to know that it exists?

I love that quote!

Also- Ls1 and rotaries both stink- I say make it electric.

 

[mndsm]

Bio-diesel!