Has anyone ever swapped a Piston into an RX-8?
#101
lightweight 17's will fit, but I don't know how much fuel you'll save and the stock wheels are already so light that any wheels that are considerably lighter cost about $600-$800 a rim. Look at some Volks and Gram Lights and you'll see what I mean.
http://www.wheelweights.net/
http://www.wheelweights.net/
I've heard there are two manufacturers of the OEM rims. One was 22 lbs, the other is 25 lbs.
#102
Registered
Thread Starter
I started with the idea of a Piston swap because the cheap KA24DE engine had more torque at mid RPM range than a RENESIS.
A lot of people look at wheel horse power (peak) but for fuel economy I'm considering how much torque can be delivered into use at any given amount of fuel. Basically Fuel-to-Torque ratio, which is Miles per gallon.
I'm considering replacing CAT with a mid pipe, replacing the muffler, using lighter and smaller wheels (because wheel is not the only thing that has weight, tires weight too), have Interceptor on top of it to make the car run lean at cruise and map it to use with only High octane.
There are other ideas like attemping to make the intake temp cooler but that's for later.
A lot of people look at wheel horse power (peak) but for fuel economy I'm considering how much torque can be delivered into use at any given amount of fuel. Basically Fuel-to-Torque ratio, which is Miles per gallon.
I'm considering replacing CAT with a mid pipe, replacing the muffler, using lighter and smaller wheels (because wheel is not the only thing that has weight, tires weight too), have Interceptor on top of it to make the car run lean at cruise and map it to use with only High octane.
There are other ideas like attemping to make the intake temp cooler but that's for later.
#104
#105
#106
Registered
Thread Starter
I AM looking for 22MPG range. The RX-8 I had before got like 15MPG or 17MPG at best and on the 15 miles trip to work I drove like 11 miles on highway.
I don't plan to pay a lot for wheels. Last time I checked the stock 18" weighted 22LB same as Dodge 18" but the Dodge wheels were 7.5" instead of 8".
I'm thinking 16" if I can get it down that much. 17" if not. One inch in wheel and a bit more in tire could count for something.
Does the lighter fly wheel accounts for anything? Or is it just as much as a Cat-less exhaust?
I have a HKS 4" steel pipe on my 240sx. It sounds glorious with a low growl (I've heard enough Mustangs, 350Z, G35, Civic Type-R, WRX to say this).
But the frikking thing is heavy and expensive. The only reason I have it is because it came with the shell. Will a cheaper and lighter 3" straight pipe sound like crap (Civic with fart can) on an RX-8?
I don't plan to pay a lot for wheels. Last time I checked the stock 18" weighted 22LB same as Dodge 18" but the Dodge wheels were 7.5" instead of 8".
I'm thinking 16" if I can get it down that much. 17" if not. One inch in wheel and a bit more in tire could count for something.
Does the lighter fly wheel accounts for anything? Or is it just as much as a Cat-less exhaust?
I have a HKS 4" steel pipe on my 240sx. It sounds glorious with a low growl (I've heard enough Mustangs, 350Z, G35, Civic Type-R, WRX to say this).
But the frikking thing is heavy and expensive. The only reason I have it is because it came with the shell. Will a cheaper and lighter 3" straight pipe sound like crap (Civic with fart can) on an RX-8?
Last edited by Soravia; 01-01-2008 at 07:02 PM.
#107
#109
Hit & Run Magnet
iTrader: (3)
more info on the intercepter x. (also note: its mazsport, not greddy. greddy has the e-manage ultimate)
http://www.mazsport.net/store/index....uct_detail&p=7
http://www.mazsport.net/store/index....uct_detail&p=7
#111
Zoom-Freakin'-Zoom
iTrader: (5)
I AM looking for 22MPG range. The RX-8 I had before got like 15MPG or 17MPG at best and on the 15 miles trip to work I drove like 11 miles on highway.
I don't plan to pay a lot for wheels. Last time I checked the stock 18" weighted 22LB same as Dodge 18" but the Dodge wheels were 7.5" instead of 8".
I'm thinking 16" if I can get it down that much. 17" if not. One inch in wheel and a bit more in tire could count for something.
Does the lighter fly wheel accounts for anything? Or is it just as much as a Cat-less exhaust?
I have a HKS 4" steel pipe on my 240sx. It sounds glorious with a low growl (I've heard enough Mustangs, 350Z, G35, Civic Type-R, WRX to say this).
But the frikking thing is heavy and expensive. The only reason I have it is because it came with the shell. Will a cheaper and lighter 3" straight pipe sound like crap (Civic with fart can) on an RX-8?
I don't plan to pay a lot for wheels. Last time I checked the stock 18" weighted 22LB same as Dodge 18" but the Dodge wheels were 7.5" instead of 8".
I'm thinking 16" if I can get it down that much. 17" if not. One inch in wheel and a bit more in tire could count for something.
Does the lighter fly wheel accounts for anything? Or is it just as much as a Cat-less exhaust?
I have a HKS 4" steel pipe on my 240sx. It sounds glorious with a low growl (I've heard enough Mustangs, 350Z, G35, Civic Type-R, WRX to say this).
But the frikking thing is heavy and expensive. The only reason I have it is because it came with the shell. Will a cheaper and lighter 3" straight pipe sound like crap (Civic with fart can) on an RX-8?
you really really need to read more and post less... really..
this should make my point...
https://www.rx8club.com/showpost.php...80&postcount=7
and to answer the ? in another thread... if you get one or two more mpg with the ceptor x on a na car, it will never pay for itself...
beers
Last edited by swoope; 01-01-2008 at 10:55 PM.
#113
The point of this question seems to have gone over a lot of peoples heads. The car looks fantastic but the engine is thirsty, lacks torque and reliability is an issue. The right engine will give 30+mpg 250k miles+ easy, rebuild proof driveability and maintenance, 180lbft torque and 190 bhp. The rotary engine has two strengths and many weaknesses, if mazda had built the car with a better engine they would have sold five times as many. The fact that you can buy an excellent example with a knackered engine for £500 ($750) is all the proof anyone without rose tinted specs needs.
Obvious candidate is the Honda s2000 engine (same gearbox I think) but it also lacks torque and costs £2000 ($3000) upwards. My choice would be a 2.5 BMW engine & gearbox, a cheap, bullet proof, superbly smooth straight six, not too big & really cheap. (£500 or thereabouts) ($750) can easily be chipped to over 200 bhp and 200lb/ft. It shouldnt affect the handling much and its rock solid proven german engineering. Has anyone had a go at this?
Obvious candidate is the Honda s2000 engine (same gearbox I think) but it also lacks torque and costs £2000 ($3000) upwards. My choice would be a 2.5 BMW engine & gearbox, a cheap, bullet proof, superbly smooth straight six, not too big & really cheap. (£500 or thereabouts) ($750) can easily be chipped to over 200 bhp and 200lb/ft. It shouldnt affect the handling much and its rock solid proven german engineering. Has anyone had a go at this?
#117
It may be less of an issue in America but in the UK where petrol is $10+ a gallon a car that does 15mpg is a disaster. Add in the lack of torque and reliability issues and the continued use of a rotary engine in any future production car must be questionable.
I re-raised the issue because there doesnt seem to be a definitive answer or anything close to one. Maybe the answer it to install a 325 bmw engine myself and report back
I re-raised the issue because there doesnt seem to be a definitive answer or anything close to one. Maybe the answer it to install a 325 bmw engine myself and report back
#118
Most people bought it for the looks and put up with the engine. Drive a straight six BMW and you will realise the rotary engine has no virtues that the bmw cant equal and it has none of the vices, its a no brainer,.
#119
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 253 Likes
on
110 Posts
Answer for what question? Piston swaps have been done, this is in a subforum dedicated to the after all. The engine doesn't really matter. The Daab turbo engine swap has the same challenges as the Izuzu swap and every LS swap.
If you feel strongly, then take action on it.
Posted From RX8Club.com Android App
If you feel strongly, then take action on it.
Posted From RX8Club.com Android App
#120
I cant find the subforum, I love the site but the indexing of subjects and the ease of use needs a tidy up. My point is that Ive seen a lot of conjecture about this subject but the engine choices seem ill considered at best. An engine thats not too difficult a fit, has the same smooth revving and power to weight that the rotary does but with added benefits of torque, easy maintenance and double the fuel economy. If its practical I`ll have a go, I think its by far the best engin e choice.
#121
Actually, I bought it for the engine and am lukewarm about its looks. And, like most enthusiasts who appreciate this car, I didn't buy it for the engine, per se, but rather for the remarkable handling the little engine makes possible. No automotive journalist ranks a straight six BMW's handling ahead of the 8s. And swapping in a larger, heavier engine would negate the 8s handling advantage. That's just basic physics.
#122
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 253 Likes
on
110 Posts
I cant find the subforum, I love the site but the indexing of subjects and the ease of use needs a tidy up. My point is that Ive seen a lot of conjecture about this subject but the engine choices seem ill considered at best. An engine thats not too difficult a fit, has the same smooth revving and power to weight that the rotary does but with added benefits of torque, easy maintenance and double the fuel economy. If its practical I`ll have a go, I think its by far the best engin e choice.
RX8Club.com > Frankenstein RX-8s > Frankenstein RX-8s
This is the breadcrumb string for where the thread is located.
This thread is IN the subforum for engine swaps: Frankenstein RX-8s.
My point about the engines wasn't the engine choices. Everyone has different engine likes and dislikes. My point was is that it doesn't matter WHICH engine you pick, the challenges will still be the same across the board. The cost and difficulty of swapping a BMW I6 is going to be pretty much the same as swapping an Mazda 20b, a GM V8, a Ford V8, an Izuzu V6, a Saab Turbo I4, a Porsche Flat 6, or a Harley V-Twin.
They ALL have the same challenges to deal with. Picking a different engine isn't suddenly easier. The ONLY engine that could be considered to be "easy" is the peripheral port 13b from the RX-7, but that is still around a $12k-$15k (USD) project, consisting of some fabrication requirements, many ECU and wiring difficulties, and exhaust, cooling, and oiling customization. And that's for an engine that is fundamentally the exact same size!
It's possible that the 2.0L MRZ from the 2006+ Miata would be "easy" to swap as well, since that car shares the same subframe and most of the same body electronics modules as the RX-8. You can bolt the front and rear subframes of the RX-8 to an NC Miata after all, the reverse is clearly true as well. But I've only heard of someone pursuing that once, and I heard no more about it. It's a far weaker engine anyway, and not much more fuel efficient.
BTW, I can't seem to find a BMW straight 6 engine that would be "double the mileage" of the 8 without also being a diesel and/or a hybrid.
You need a City rating of around 32mpg and a highway rating of at least 44mpg in order to classify as "double". And you have to consider that a portion of mileage calculations is the aerodynamics which will NOT be transfered from that BMW to the RX-8. An RX-8 that isn't hitting 16mpg city and 22mpg highway is an RX-8 that has something broken. Might be parts or it might be the driver, but it doesn't change that fact.
I also don't see you pitching a fit over vehicles that get significantly worse mileage... If mileage is such a big concern, get a car with better and be done with it.
You may also want to consider that even assuming you find an engine that allows "double the mileage", doing a swap that costs you even 6,000 quid is going to take a very long time to break even on the fuel costs vs swap costs.
Last edited by RIWWP; 09-06-2013 at 09:25 AM.
#123
The RX8 has a better drag coefficient than the 3 or 5 series BMW, assuming the engine will fit without changing the bonnet line its figures will improve slightly. My mates 325i will return close to 45mpg on a run and 28 overall, I think this is close enough to warrant the experiment. I plan to do all the work myself except the electrics where i have some help. There are no cars for the common man in the UK with worse mileage so the point is irrelevant.
My plan is to buy the RX8, recon the rotary and sell it to fund the change. It would appear from this forum that custom garage service hourly rates in America are very high compared with Europe.
My plan is to buy the RX8, recon the rotary and sell it to fund the change. It would appear from this forum that custom garage service hourly rates in America are very high compared with Europe.
#125
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 253 Likes
on
110 Posts
No one here thinks the rotary is a mass market engine. It's a niche engine for sure. Your 10% is way way way too high.
If you want to swap and think you can do it easily, then just go ahead and do it. We know the drawbacks of the engine and most of us love it anyway. No need to continue bemoaning the topic. You aren't going to suddenly convince us of anything we didn't already know.
My attempts were only to try to get you to understand that it won't be as easy as you think it is, but I have no stake in that so... have fun...
If you want to swap and think you can do it easily, then just go ahead and do it. We know the drawbacks of the engine and most of us love it anyway. No need to continue bemoaning the topic. You aren't going to suddenly convince us of anything we didn't already know.
My attempts were only to try to get you to understand that it won't be as easy as you think it is, but I have no stake in that so... have fun...