Future RX-8 After-market Mods
12-07-2002, 01:00 PM
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Future RX-8 After-market Mods
So how do you guys think the future will bode for after-market mods for the 8? Does the RX-8 have the potential for below 5 second 0-60 times and 13 second 1/4 miles? How high would you speculate that the HP could be boosted N/A and with a Turbo?
12-07-2002, 08:15 PM
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Possible mods: Engine
1. Exhaust (cat-back)
2. Hi-Flow Cat or remove it
3. Intake
4. Chip (Ignition Advance, Fuel Curves)
5. Bridge Porting
6. Headers (kill the evil pre-Cats)
I believe this engine with most of these mods should be able to pull 300 hp and probably more. As I would expect some of these mods to be part of the MazdaSpeed version and its expected to pull 300.
Now the whole other way of doing this would be an aftermarket turbo system. Which I would consider a little more risky, but with the aftermarket availability of the RX-7 I would expect no less than to have several decent kits to come out for the renesis. I think to go FI on the renesis the skies the limit. As Mazda has been quoted as saying this engine would work well with FI. It all depends on how well the turbo systems are engineered for the car as to how reliable they will be.
We can only hope for the aftermarket support the RX-7 saw.....
Then I'm sure a 5 second 0-60 could be had. As I too hope to some day be in the low 5's and mid to low 13's
1. Exhaust (cat-back)
2. Hi-Flow Cat or remove it
3. Intake
4. Chip (Ignition Advance, Fuel Curves)
5. Bridge Porting
6. Headers (kill the evil pre-Cats)
I believe this engine with most of these mods should be able to pull 300 hp and probably more. As I would expect some of these mods to be part of the MazdaSpeed version and its expected to pull 300.
Now the whole other way of doing this would be an aftermarket turbo system. Which I would consider a little more risky, but with the aftermarket availability of the RX-7 I would expect no less than to have several decent kits to come out for the renesis. I think to go FI on the renesis the skies the limit. As Mazda has been quoted as saying this engine would work well with FI. It all depends on how well the turbo systems are engineered for the car as to how reliable they will be.
We can only hope for the aftermarket support the RX-7 saw.....
Then I'm sure a 5 second 0-60 could be had. As I too hope to some day be in the low 5's and mid to low 13's
12-08-2002, 03:00 AM
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well fritts, i dunno how much more power this engine'll make with SOME of those modifications... the chip'll make you some, but i'm skeptical about an exhaust swap (other than maybe for wieght, a la the FD?? i don't think Mazda will want to tie up as much power as they can with this unit... it's not a grocery-fetcher), and cat tech has really come along but you'd probably need to get rid of 'em to go over 300, and an intake swap is really really sketchy, with all the engineering that's gone into the variable-length induction runners... unless you wanted to just go with a really, REALLY short one 
heh heh... but what do i know?? i'd be anxious to see what SCC does to really @#%! an 8 up, and how it turns out...
heh heh... but what do i know?? i'd be anxious to see what SCC does to really @#%! an 8 up, and how it turns out...
12-08-2002, 11:12 PM
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The exhaust manifold on the Renesis looks terribly inefficient - a proper header will be an interesting design, it appears that with the side exhaust ports on either side of each rotor, the ones toward the center of the motor currently dump into one tube, while the end ports each have their own, giving a two rotor engine a three tube manifold. I am sure that the center ports could benefit from their own separate header tubes, making all four equal length of course. I suspect a good chunk of power could be made here, though designing it to work with what is sure to be a close-coupled catalytic converter will be difficult. The day of the simple two-rotor header is over.
I've always felt there was serious potential in higher compression rotors if anyone made them relatively inexpensively. Should the Renesis stay a naturally aspirated motor I see potential here as well - not that you can't turbocharge it instead.
I don't know if there will be much to be gained from a catback exhaust - these days catbacks are pretty efficient from the factory. The RX-8 is said to not be particularly quiet so I suspect its stock catback may be less restrictive than those put on naturally aspirated RX-7s in the past.
Unfortunately, whereas the next step in a naturally aspirated piston engine is to change the cams, porting a rotary will require an engine rebuild, and no one has much of an idea yet how much can be gained over the stock Renesis ports. If they're designed to flow well at 9000 RPM from the factory I suspect there may not be much to be gained, though perhaps with the radically different exhaust ports the limits on how far the porting can be taken may have been moved. I'd be curious to see if they can bridgeport the exhaust end, too. :D
From the bits I've read it sounds like the car could use a slightly stiffer setup for less body roll, and according to Automobile magazine this month the longer wheelbase, while making the car more predictable than the RX-7, also makes it not have that same sparkling turn-in, so perhaps something could be done in the suspension to improve that.
I hate to say it, because I'm no great fan of aftermarket wings, but the rear of the RX-8 is crying out for SOMETHING. It'd be subtle, like the stock wings on the 88 and up FC and early FDs.
I've always felt there was serious potential in higher compression rotors if anyone made them relatively inexpensively. Should the Renesis stay a naturally aspirated motor I see potential here as well - not that you can't turbocharge it instead.
I don't know if there will be much to be gained from a catback exhaust - these days catbacks are pretty efficient from the factory. The RX-8 is said to not be particularly quiet so I suspect its stock catback may be less restrictive than those put on naturally aspirated RX-7s in the past.
Unfortunately, whereas the next step in a naturally aspirated piston engine is to change the cams, porting a rotary will require an engine rebuild, and no one has much of an idea yet how much can be gained over the stock Renesis ports. If they're designed to flow well at 9000 RPM from the factory I suspect there may not be much to be gained, though perhaps with the radically different exhaust ports the limits on how far the porting can be taken may have been moved. I'd be curious to see if they can bridgeport the exhaust end, too. :D
From the bits I've read it sounds like the car could use a slightly stiffer setup for less body roll, and according to Automobile magazine this month the longer wheelbase, while making the car more predictable than the RX-7, also makes it not have that same sparkling turn-in, so perhaps something could be done in the suspension to improve that.
I hate to say it, because I'm no great fan of aftermarket wings, but the rear of the RX-8 is crying out for SOMETHING. It'd be subtle, like the stock wings on the 88 and up FC and early FDs.
12-22-2002, 01:11 AM
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Depends on emmissions. If you're in Cali, you may be screwed, but in regions without smog testing you can delete everything but a header, presilencer, and power pulse muffler (with associated plumbing, of course) and free up horsepower otherwise choked off by the cats.
Rotaries are intensely sensitive to exhaust tuning. Opening it up (removing cats and restrictive stock mufflers), while at the same time keeping enough backpressure to properly pulse the exhaust pressure wave for proper scavenging, is one of the most reliable bolt-on mods you can make.
I like the fact that the engine is N/A. The twin turbo in the FD (3rd gen) was overstressed, and led to reliability issues or essential modifications. A more mild turbocharging, like the TII (1986-1991) or the 12A Jspec turbo (1979-1985) gives reliable boost without the works-great-when-everything-runs-properly-but-lookout! factor.
Rotaries are intensely sensitive to exhaust tuning. Opening it up (removing cats and restrictive stock mufflers), while at the same time keeping enough backpressure to properly pulse the exhaust pressure wave for proper scavenging, is one of the most reliable bolt-on mods you can make.
I like the fact that the engine is N/A. The twin turbo in the FD (3rd gen) was overstressed, and led to reliability issues or essential modifications. A more mild turbocharging, like the TII (1986-1991) or the 12A Jspec turbo (1979-1985) gives reliable boost without the works-great-when-everything-runs-properly-but-lookout! factor.
12-22-2002, 01:43 AM
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Originally posted by manntis
The twin turbo in the FD (3rd gen) was overstressed, and led to reliability issues or essential modifications.
The twin turbo in the FD (3rd gen) was overstressed, and led to reliability issues or essential modifications.
The problem was mainly overheating.
12-22-2002, 02:02 AM
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tell that to the members of my rotorhead club that have needed rebuilds on FD engines when they went boom.
Great for street driving, but once you get into 'spirited' driving it is widely accepted (even conceeded by Mazda) that the twin turbo configuration was rushed to market without full testing.
Great for street driving, but once you get into 'spirited' driving it is widely accepted (even conceeded by Mazda) that the twin turbo configuration was rushed to market without full testing.
12-22-2002, 04:03 PM
#9
Originally posted by manntis
tell that to the members of my rotorhead club that have needed rebuilds on FD engines when they went boom.
Great for street driving, but once you get into 'spirited' driving it is widely accepted (even conceeded by Mazda) that the twin turbo configuration was rushed to market without full testing.
tell that to the members of my rotorhead club that have needed rebuilds on FD engines when they went boom.
Great for street driving, but once you get into 'spirited' driving it is widely accepted (even conceeded by Mazda) that the twin turbo configuration was rushed to market without full testing.
The majority of the blown engines were a result of improper tuning once the engine was modified. Heat played a major part as well (especially the pre-cat). Everyone knows how un-appaptive the stock computer was to simple mods. There are a number of stock 3rd gens on the road with ungraded vacuum lines and removed precats that have allowd those cars to go over 100k miles. Not many though!
12-22-2002, 06:32 PM
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True duel exhaust 28% over stock: http://www.mazdatrix.com/r-ex86nt.htm
Intake on n/a FC ~5%: http://www.rx7club.com/forum/showthr...threadid=95492
New housings (see pic) probably about 50%+ on renesis. :D
Intake on n/a FC ~5%: http://www.rx7club.com/forum/showthr...threadid=95492
New housings (see pic) probably about 50%+ on renesis. :D
12-22-2002, 08:00 PM
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Originally posted by manntis
tell that to the members of my rotorhead club that have needed rebuilds on FD engines when they went boom.
Great for street driving, but once you get into 'spirited' driving it is widely accepted (even conceeded by Mazda) that the twin turbo configuration was rushed to market without full testing.
tell that to the members of my rotorhead club that have needed rebuilds on FD engines when they went boom.
Great for street driving, but once you get into 'spirited' driving it is widely accepted (even conceeded by Mazda) that the twin turbo configuration was rushed to market without full testing.
True, the TT system was rushed. This led to engine overheating. Mazda later fixed this, but not until after they stopped selling the car in North America. Series 8 FDs (99-02) are much more reliable while running higher boost.
12-23-2002, 09:02 AM
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Originally posted by m477
Again, the majority of FD engines failures are caused by OVERHEATING, not because the engine is running too much boost.
True, the TT system was rushed. This led to engine overheating. Mazda later fixed this, but not until after they stopped selling the car in North America. Series 8 FDs (99-02) are much more reliable while running higher boost.
Again, the majority of FD engines failures are caused by OVERHEATING, not because the engine is running too much boost.
True, the TT system was rushed. This led to engine overheating. Mazda later fixed this, but not until after they stopped selling the car in North America. Series 8 FDs (99-02) are much more reliable while running higher boost.
I'm totally confident that a NA RENESIS engine will last much longer than 100K miles. I wouldn't be surprise if many will go 250K miles. NA first & second gen RX-7's have a very good reputation for live long lives.
On the other hand, if the MazdaSpeed RX-8 doesn't comes FI, I will be either considering a MazdaSpeed 6 or adding a turbo kit to a RX-8. I don't think I will be satistfied with anything less than 325HP from a MazdaSpeed RX-8. Also, a FI kit will give the RENESIS engine a very healthy dose of low end torque that many drivers will be yurning for.
12-23-2002, 10:08 AM
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My dad had a 1980 RX-7 for 21 years on the same engine and almost 300k miles on the original engine. He finally sold it last year to a guy that races dune buggies with rotaries and bought a Toyota Corolla :o (no puking smilies on this board?? haha). Granted, he wasn't running any boost, but if that doesn't say something about the rotary, I don't know what will....
12-23-2002, 12:47 PM
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rotories actually do have long-life potential (only 3 moving parts - two doritos on a toothpick!) as long as you change the oil on a regular basis and don't overheat them.
What I stated above about overstressing - BOOSTING CREATES HEAT. that's why intercoolers are a must for any significant boost, but the car didn't breathe well (no vents on stock hood, etc.)
Mazda rushed the twin turbo to market to compete with the 300ZX, Supra, etc. (yes I know it's prettier and lighter - I mean compete as far as consumer demand goes, and the words 'twin turbo' sells cars) I'm glad they took their time to get the RX-8 right.
Incidentally, the 1984-1985 RX-7 was available with a 13B (135 HP) option in the GSL-SE model as opposed to the 12A N/A in the rest for that generation - except the 12A Turbo available in Japan (165 HP). Why didn't North America get the extra 30 ponies from the 12AT? The 13B had a better torque band, sure, but mainly because in Japan there are rotary repair shops in every town, whereas in North America even many Mazda dealerships are scared of working on those engines... and statistically speaking, turbocharging an engine decreases its reliability.
In fact, many automotive engineers view turbocharging as a stop-gap solution. Developing all-new engines is expensive and time consuming, so slapping a turbo on engines in their mid-life is one more thing to constantly 'improve' the car before the next model comes out - sort of like added features, etc.
Look at the 300ZX, or even the New Beetle. First comes the N/A version. Then one with more power features or other gimmicks (T-tops, power sun roof, enhanced stereo, convertible, etc.) Then a Turbo version. Then an all-new generation.
Sometimes the order of 'enhancements' are shuffled around, but that's generally the arc of a car's marketing lifespan.
To combat the perception of unreliable engines (rekindled by the 3rd gen after very reliable 1st and 2nd gen RX-7s) Mazda decided to make an N/A rotary with virtually the same output as their previous twin turbo. Less plumbing, fewer parts, far less overheating potential.
I say give the new engine a chance. Mazda engineers have proven their brilliance time and time again. Try the N/A engine before you second guess them on this one.
(interesting fact: while designing cars Mazda usually cross-co-ordinates things so everything works well as a unit, but for some reason designing the twin turbo setup of the 3rd gen RX-7 was sub-contracted to an Aussie firm)
What I stated above about overstressing - BOOSTING CREATES HEAT. that's why intercoolers are a must for any significant boost, but the car didn't breathe well (no vents on stock hood, etc.)
Mazda rushed the twin turbo to market to compete with the 300ZX, Supra, etc. (yes I know it's prettier and lighter - I mean compete as far as consumer demand goes, and the words 'twin turbo' sells cars) I'm glad they took their time to get the RX-8 right.
Incidentally, the 1984-1985 RX-7 was available with a 13B (135 HP) option in the GSL-SE model as opposed to the 12A N/A in the rest for that generation - except the 12A Turbo available in Japan (165 HP). Why didn't North America get the extra 30 ponies from the 12AT? The 13B had a better torque band, sure, but mainly because in Japan there are rotary repair shops in every town, whereas in North America even many Mazda dealerships are scared of working on those engines... and statistically speaking, turbocharging an engine decreases its reliability.
In fact, many automotive engineers view turbocharging as a stop-gap solution. Developing all-new engines is expensive and time consuming, so slapping a turbo on engines in their mid-life is one more thing to constantly 'improve' the car before the next model comes out - sort of like added features, etc.
Look at the 300ZX, or even the New Beetle. First comes the N/A version. Then one with more power features or other gimmicks (T-tops, power sun roof, enhanced stereo, convertible, etc.) Then a Turbo version. Then an all-new generation.
Sometimes the order of 'enhancements' are shuffled around, but that's generally the arc of a car's marketing lifespan.
To combat the perception of unreliable engines (rekindled by the 3rd gen after very reliable 1st and 2nd gen RX-7s) Mazda decided to make an N/A rotary with virtually the same output as their previous twin turbo. Less plumbing, fewer parts, far less overheating potential.
I say give the new engine a chance. Mazda engineers have proven their brilliance time and time again. Try the N/A engine before you second guess them on this one.
(interesting fact: while designing cars Mazda usually cross-co-ordinates things so everything works well as a unit, but for some reason designing the twin turbo setup of the 3rd gen RX-7 was sub-contracted to an Aussie firm)
12-24-2002, 10:06 PM
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With an after market TURBO from greddy like a T-78... The Rx-8 will have about 360 HP!!!
then with exhaust, intake, etc.... over 400 easily
making quarter mile in the 12s!!!
then with exhaust, intake, etc.... over 400 easily
making quarter mile in the 12s!!!
12-26-2002, 09:52 AM
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Originally posted by xkpbreaker
With an after market TURBO from greddy like a T-78... The Rx-8 will have about 360 HP!!!
then with exhaust, intake, etc.... over 400 easily
making quarter mile in the 12s!!!
With an after market TURBO from greddy like a T-78... The Rx-8 will have about 360 HP!!!
then with exhaust, intake, etc.... over 400 easily
making quarter mile in the 12s!!!
---jps
12-26-2002, 01:27 PM
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Might wanna RE-READ dat.....
I said after an aftermarket TURBO... which will usually add about 100-110 hp.....
so stock....... 250+110= 360!!!
then intake + exhaust + 360 = about 400hp!!
do the math..
I said after an aftermarket TURBO... which will usually add about 100-110 hp.....
so stock....... 250+110= 360!!!
then intake + exhaust + 360 = about 400hp!!
do the math..
12-26-2002, 02:14 PM
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Originally posted by xkpbreaker
I said after an aftermarket TURBO... which will usually add about 100-110 hp.....
do the math..
I said after an aftermarket TURBO... which will usually add about 100-110 hp.....
do the math..
the thing is, performance enhancement isn't that simple. there are so many factors which impact on performance, and so many variables which can be changed...
the most important thing to realize that there are almost no linear relationships in terms of changing one thing to affect some outcome... actually, there probably isn't a single one...
one cannot simply assume that at 1 bar the engine makes 250hp, then with 1.5 bar of boost (that's "2.5 bar" in the combustion chamber), with 2.5 times the amount of fuel, that you'll make 2.5 times the amount of torque when on boost... it would be cool if it worked that way, but then every guy and his grandma could get 100% of the performance capability of any engine in the universe, no matter the regulations (with enough money...)...
i know you're well meaning, and ya, you MIGHT be able to BARELY get the engine to run for a while 100hp over stock with the rest of the car stock, with a brand-name turbo kit... but... unlikely at best. not to mention the problems you'd have with a setup like that.
yeah, there are a lot of factors... adding an intake and exhaust will net you 40hp when you're trying to boost 100hp into an engine, but it won't net you 40hp with the rest of the engine stock... in fact, it may lose you more torque (at the bottom) than you gain (at the top)...
i don't pretend to know everything (i hope), but it really won't work that way, sorry bud.
it can be done, but not so simply.
12-26-2002, 02:22 PM
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With all the factors involved in producing an aftermarket turbo kit for a NA engine, not to mention its a rotary. Our only hope is that major RX-7 tuners get involved and use their knowledge to produce performance upgrades.
I hope the renesis can get to the 300hp mark NA. If so that's the way I'll go. Especially without a factory turbo option...
I hope the renesis can get to the 300hp mark NA. If so that's the way I'll go. Especially without a factory turbo option...