OK. So I am new to this forum. This is my first post. Yay for me. So my question is this: Say I had an unlimited budget and wanted to build a turbo kit capable of dumping 25+ psi onto the renny. Is this possible? 4" piping, new internals, beefed up seals, ignition, etc. I have seen plenty of FD's dumping lots of boost but no 8's. wtf?

OK. So I am new to this forum. This is my first post. Yay for me. So my question is this: Say I had an unlimited budget and wanted to build a turbo kit capable of dumping 25+ psi onto the renny. Is this possible? 4" piping, new internals, beefed up seals, ignition, etc. I have seen plenty of FD's dumping lots of boost but no 8's. wtf?

I haven't ever seen anyone running much more than half that. From what I've heard, no one has really pushed the engine to breaking point, so no one knows how far it will go.

Mazsport got over 360whp with 13PSI. With beefed up seals (I assume you mean apex seals) I don't see why you couldn't go higher.

Use race gas. Give us dynoes :Eyecrazy:

I haven't ever seen anyone running much more than half that. From what I've heard, no one has really pushed the engine to breaking point, so no one knows how far it will go.

Mazsport got over 360whp with 13PSI. With beefed up seals (I assume you mean apex seals) I don't see why you couldn't go higher.

Use race gas. Give us dynoes :Eyecrazy:



Yes of course apex seals. I would say race gas would also be a must with this much boost. I am assuming people that have done FI kits have not bothered to upgrade apex seals and that is why no one wants to push more than 13 psi?

With 10:1 static compression you will have a very hard time pusing that kind of air into a renesis. But if you got the money give it a shot and let us know how it goes.

Yes of course apex seals. I would say race gas would also be a must with this much boost. I am assuming people that have done FI kits have not bothered to upgrade apex seals and that is why no one wants to push more than 13 psi?

I don't think it's that simple. Apex seals probably fail first but they're not the only thing that fails.

With an unlimited budget you could afford a complete custom motor but I'm not sure who you would turn to for that unless you could do it yourself.

With an unlimited budget, hell, lose the Renny all together. Swap a 20B in and if you still want more power order a booster from the shuttle program.

Well, with an unlimited budget, what you would do would be buy about 1000 motors. Then you would basically design a pretty badass turbo system from the ground up. Then, install motor one. Crank boost until something breaks. When something breaks, design a replacement for it, and incorporate that design when you drop the next motor in. Keep replacing motors until you're up to 25 psi or wherever you want to be. If you can run 25 psi at 9:1 compression on a given fuel system, maybe that's like running 21 psi at 10:1. It's not worlds different, just more difficult.

There are very few Renesis engines putting down 350 whp (to be honest, quantifying enginges by the boost they run instead of the whp which is really what you are after unless you are trying to hit a certain pitch on your BOV doesn't make sense anyway) and none that I know of doing 400 whp. Given enough time and money, you could build a system that began as a Renesis that will do 1000 whp, but the time and money just hasn't been done yet. Who knows how many engines, builds, and designs it will take. Usually, with cars, this is spread over many owners just pushing what can be done but with unlimited money I guess 1 guy could do it.

Seeing as to my knowledge it hasn't been done, I don't know of anyone who could concretely say what is the best way to do it. You can just make an educated guess, design/fab it up, and see if you missed anything.

Brilliant first post.

The two biggest things holding people back from doing huge horsepower FI setups one the Renesis are 1) the lack of engine management systems (the Cobb AP seems to have started to change this) and 2) the relatively high compression ratio of 10:1 which puts a lot of pressure on apex seals that cost $1600 to upgrade.

The two biggest things holding people back from doing huge horsepower FI setups one the Renesis are 1) the lack of engine management systems (the Cobb AP seems to have started to change this) and 2) the relatively high compression ratio of 10:1 which puts a lot of pressure on apex seals that cost $1600 to upgrade.

you missed part B of number 1... even with the proper tools for tuning, there's been issues tuning it once you get to those power ranges I believe.

you missed part B of number 1... even with the proper tools for tuning, there's been issues tuning it once you get to those power ranges I believe.

You'd have to use larger tubing where the MAF sensor is and recalibrate, definitely some upgraded coils possibly with longer dwell times, bigger fuel pump and injectors, and one hell of a cooling system.

I haven't really researched the XTREME rx-8 turbo'ing. I've always been more interested in the maximum low-lag power range, so I don't know what other tuning barriers you'd run into?

I think you'll be wantin' some custom low compression Rennie rotors wif dat order, mon.

This is complete speculation and I'm no expert, but you might be able to increase displacement/get better compression by taking very precise, shallow scoops out of the side irons (which I think are fairly thick). Sort of like the channels in the rotor faces, but in the side housings.

The two biggest things holding people back from doing huge horsepower FI setups one the Renesis are 1) the lack of engine management systems (the Cobb AP seems to have started to change this) and 2) the relatively high compression ratio of 10:1 which puts a lot of pressure on apex seals that cost $1600 to upgrade.

The Renesis seals are basically the same materials as in the REW. The 10:1 compression ratio in this scenario is a little negated. Cylinder pressure, while dictated by compression - amongst other variables (fuel, air, ignition timing, etc...) - is also going to be dictated by the supercharging. Point being, 9:1 compression and 40 lbs of air won't yield that much less stress than 10:1 and 40 lbs of air.

This is complete speculation and I'm no expert, but you might be able to increase displacement/get better compression by taking very precise, shallow scoops out of the side irons (which I think are fairly thick). Sort of like the channels in the rotor faces, but in the side housings.

For the minute amount you'd take out, this will not increase displacement to any standard that is worthwhile. Further, it would be a bad idea to extend the engine seals as the more they are out of their grooves and exposed the more prone to failure they will become. The seals are still - as always - a prime mode of failure. And of course, there's the overriding need for the seals to actually seal and keep the three chamber's functions separate.

This is complete speculation and I'm no expert, but you might be able to increase displacement/get better compression by taking very precise, shallow scoops out of the side irons (which I think are fairly thick). Sort of like the channels in the rotor faces, but in the side housings.

what is no.

beers :beer:

i'll take fantasies for 2000.

Hmm... So aside from the obvious upgrades that would be needed in order for the renny to handle this much boost, it seems the throttle body and upper intake and probably the entire intake system would have to be bigger in order to have enough air be able to pass through it. Could the intake be re-manufactured to look and function exactly the same but have a bigger inside diameter? Who would/could accomplish this? ITBs? I realize that it would be cheaper to just slap a 20b into the 8 and just go from there but I have plans on doing that to an FD. I know the REW can be modded to handle tons of boost so why not the Renesis?
I would probably have Smokin Joe's out here on LI do the build as I have heard good things first hand about them. Anyone here have any experience with that shop?

PS Thanks to MM for the compliment. I have waited too long to ask this question here.

As to my other question in my second post, has anyone upgraded their renny with high performance apex seals? What is stopping someone with a turbo, different wastegate spring and boost control from turning the boost up to 20 psi?

As to my other question in my second post, has anyone upgraded their renny with high performance apex seals? What is stopping someone with a turbo, different wastegate spring and boost control from turning the boost up to 20 psi?

... just a random answer to this question... not the most appropriate one, but still....

i dont know how many people here have turbo's that will do that in ANY kind of efficient manner...?

As to my other question in my second post, has anyone upgraded their renny with high performance apex seals? What is stopping someone with a turbo, different wastegate spring and boost control from turning the boost up to 20 psi?

You need to get off the seals. They're not holding us back. Also why are you talking about messing with the wastegate spring then using a boost controller?

Apex seals aren't hold us back. So get off the "high performance seals" train.

Also, get off the boat of "25 psi this" and "20 psi" that. PSI is a very loose measurement when talking power. You need to think it terms of airflow, not pressure. Like 55 lb/min, or 65 lb/min of air.

The high compression also isn't holding us back. Higher compression gives us a greater starting point, so we can (theoretically) run less airflow to achieve the same power. It just requires better and more careful tuning.

Maybe he wants to eventually use his blowoff valve to fill up his tires when they are low. Once you get up to 40ish PSI, you should be set for street use.

I would think you would need better apex seals in order for the engine to handle more heat and pressure. Why do they even sell high performance apex seals if that is not what is holding us back? If nothing is holding us back then why have I not seen anyone pushing more than 13 psi? If it is only a matter of airflow, that leads me back to my 3rd post.

Blowoff valve hooked into tires and tire pressure monitor system ftw...

The high compression also isn't holding us back. Higher compression gives us a greater starting point, so we can (theoretically) run less airflow to achieve the same power. It just requires better and more careful tuning.

Gotta disagree. If we had lower comp rotors we'd be seeing 400+whp Renesis engines on pump gas right now.

Why do they even sell high performance apex seals if that is not what is holding us back? If nothing is holding us back then why have I not seen anyone pushing more than 13 psi?


Why do they sell those super +80mpg +100hp plug in chips on ebay if we don't need them?

I would think you would need better apex seals in order for the engine to handle more heat and pressure. Why do they even sell high performance apex seals if that is not what is holding us back? If nothing is holding us back then why have I not seen anyone pushing more than 13 psi? If it is only a matter of airflow, that leads me back to my 3rd post.

Blowoff valve hooked into tires and tire pressure monitor system ftw...

Give me a link to those "high performance" apex seals you are talking about.

Gotta disagree. If we had lower comp rotors we'd be seeing 400+whp Renesis engines on pump gas right now.

It's true it would be easier to achieve that power on lower compression. Tuning is more key with higher compression, and quality of gas, etc etc. I just don't think it's the answer to our problems.

he wants the airplane rotary seals that eat housings.

I think hes talking about these type of apex seals. http://www.rotormaster.com.au/subPage.asp?cid=12
Imo the thing thats holding us back is the tuning , the high compression of 10:1 and quality of fuel , i think you can get passed 400+whp with race fuel. Shouldn't the small displacement also be a factor? I would also like to know more about this subject :)

As people muck around in the 300-400 whp range, I don't see apex seal failures really being sited. I don't see many people going "man, this is as far as it goes before I need race gas." I think getting to the limit of the stock ignition system (330ish whp) is quite doable right now but you don't have a ton of people there and looking for more. It's going to take time, money, and experimentation.

reaching the point where the OEM ignition runs into spark blowout is VERY doable... its being surpassed by a few people already with no issue

the tuning capability is there for well beyond numbers we are seeing now, just being precisely tuned is the key. as has been said, compression ratio/availible pump gas characteristics... some other things are also in the way for most people trying to break those kinds of numbers - driveline, first being the tranny

The big reason people aren't "just cranking up the boost" is also because things tend to break (other than the motor) when you surpass double the factory horsepower. Like transmissions, axles, rear ends, bending suspension parts, twisting powerplant frames, snapping motor mounts, etc etc.

I think the biggest factor IS money. Sure the FDs are able put down alot of power, but that car is well over a decade old. With enough time and development, Im sure we will see alot of people putting down a reliable 400+ whp. The rotary isn't a "mainstream" engine, so development for it is slow. Over the next couple of years, I estimate we'll see big improvments in power outputs. It just takes time.

Most of us love driving out cars and dont want to break them. It is a fun car to drive with the stock power, double it and it is a blast. When people get tired of 300-350HP and have money burning a hole in there pockets they will start pushing it farther. When the envelope gets pushed, things will break, someone will improve the broken part and then move forward until another part breaks and they do it again until all the week links have been broken and fixed. Takes time, money and a lot of tow trucks.

300-350 is good. Once you edge closer to 400, you need to invest a lot more cash than just for FI. We also have the issue of the side exhaust ports being more of a restriction.

When does the exhaust ports become a restriction?

Just a thought: Why not just rip off the entire intake manifold, port the intake ports on the motor, then manufacture custom intake tubing from the newly ported ports right into the throttle body. Yes this would eliminate all the Mazda engineered intake ridiculousness and most likely give you some ecls, but it may allow for more airflow as to accommodate more boost. This method would be strictly for turbo applications btw. I think that lowering the compression ratio is key for getting more hp out of the ren in a FI application for the street. I am actually willing to take the next step and try something different on my 8 which is why I have started this discussion in the first place. The direction I go needs to be carefully researched and planned before anything else so I appreciate all the input I have received thus far regarding this and would love to hear more. Thanks.

Just as a side note, I believe the Mazda team has done a wondrous thing with the intake manifold but it seems that they did not have FI in mind when they created it. I just feel that something entirely different may have to be done to make the 8 really up to the power levels that we have been seeing in 7s for quite a while. I think the ren can handle much more than the rew and I want to prove it.

^well of course the renny wasn't built for FI its N/A from the factory. The Rx7 fd came in turbo stock , and the engine itself is made for a turbo. Whenever you make an engine that was N/A from the factory and try to modify it to hit boost , most of the time its going to cost more. Also how do you plan on getting lower compression ratios? Wouldn't alchohol/methanol injection help on how much power the renny can achieve on pump gas? Does anyone on the forum use alchohol/methanol injection?

Just a thought: Why not just rip off the entire intake manifold, port the intake ports on the motor, then manufacture custom intake tubing from the newly ported ports right into the throttle body. Yes this would eliminate all the Mazda engineered intake ridiculousness and most likely give you some ecls, but it may allow for more airflow as to accommodate more boost..

good point - do it !

^well of course the renny wasn't built for FI its N/A from the factory. The Rx7 fd came in turbo stock , and the engine itself is made for a turbo. Whenever you make an engine that was N/A from the factory and try to modify it to hit boost , most of the time its going to cost more. Also how do you plan on getting lower compression ratios? Wouldn't alchohol/methanol injection help on how much power the renny can achieve on pump gas? Does anyone on the forum use alchohol/methanol injection?

Do you actually read or do you just post off the top of your head?

Aluminum rotor housing = lower temperature?? I have heard that aluminum rotors end up seizing fairly quickly. But what if you are just using aluminum rotor housings with cast iron rotors? I am pretty sure I remember seeing some vendor either selling or developing aluminum rotor housings. Anyone know about this?

The OE housings are aluminum.

I am all confused in the head now. I should just get this and call it a day: http://cgi.ebay.com/ebaymotors/3-ROTOR-20B-Race-Motor-Mazda-RX-7-Cosmo-Engine_W0QQitemZ270251935242QQcmdZViewItem?hash=it em270251935242&_trksid=p3286.m14.l1308

frick, too bad that already sold, it would have been nice to buy it and then replicate it a couple times....lol