rotarygod

If someone were to make Renesis rotors that were based off of the 8.5:1 RX-7 castings, would there be any interest here for them? I'm curious. Keep in mind I am not making or selling them but I would like to get a good idea of how many people would potentially be interested in them should they someday become available.

The idea would be to copy an 86-88 Turbo II RX-7 rotor in casting and then machine out the seal grooves around the Renesis design with the exception of the apex seal grooves which would be 13B sized. The rotors would gain weight but they would be a full point and a half lower in compression and by far be the strongest rotors you could get since '88 which had the strongest. That's why they would be the best to copy. The other idea would be to copy the casting thickness of these rotors but then have different machining in place to give the desired compression ratio.

Keep in mind that STOCK 13B rotors cost about $1200 per pair, Renesis rotors cost about $900 per pair, and Racing Beat modified Renesis rotors cost $2000 per pair. Do you think anyone would consider a stronger low compression set of Renesis rotors for let's say $1500?

What are the opinions on this? Keep in mind I have not made any and am not selling anything so don't get excited. I have an idea though that may help us out but I'm not saying how just yet. I really want to get an idea of feasibility to see if it is even worth pursuing.

Nemesis8

iTrader: (3)

I would rather have the side seal issues resolved by the time I crack open my Renesis one day. Will these tackle this weakness? I can see where this is going - 400 HP here we come.

rotarygod

Unfortunately with a side exhaust port I don't see how to change that. Get the Richard Sohn OMP adapter, use 2 stroke oil, and rev it up every once in a while and hopefully you won't have a carbon issue messing with the side seals.

morkusyambo

I am definately interested, and willing to spend 1500. From all the questions I have asked, it seems like lower compression is going to be the safer AND more reliable way to make 400+ horsepower on pump gas w/FI

nycgps

iTrader: (1)

My original plan is to open my Engine at about 60K miles for 2 reasons,

First is to see how much *Carbon* have inside the motor, since I want to show the world that what is it like after 60K miles of Synthetic oil motor use.

Second is to change it with Racing Beat's Rotor. Cuz at that time I think I will go FI with it, anything lighter (or stronger?) will be helpful. and so far I think RB is the only company that has something like that (for Renesis at least)

So yes Im interested in this kind of project(or imagination?)

ChrisRX8PR

iTrader: (1)

I would buy a set. That would be awesome. That would be all thats needed to compliment the renesis breathing ability . now Im all excited and they dont even exist...:P

Chris...Esmeril

Wanganrx8

i would probably get em if they were out

gh0st

right now, id day id wait till i needed to open up the motor to get them but if they come out, i could see myself impulse buying these. discipline is over rated.

id like to see how it would affect the power band though. you would have an easier time tuning the car to max turbo efficiency (20+ lbs for most dual ball bearing turbos) but the i was told at seven stock that the renesis starts to lose efficiency below 9:1 compression NA. not that you would really care if you had a snail bolted onto your motor.

Kane

iTrader: (1)

I could see myself paying $1500 for these, but my main concern would be drivability with the boost way up. Does anyone have exp with a rotary pushing 15 or more lbs of boost and how it feels for day to day driving as I would prolly only track it a few times a year.

nycgps

iTrader: (1)

FD guys does it all the time

mysql101

then don't floor it?

or just hit the low setting on your boost controller and do 8 psi for street.

Kane

iTrader: (1)

I hate being an idiot... good point.

ddub

Why 8.5:1? Why not the s5/FD 9.0:1? Those seemed to work fine with FD's and s5's... Don't see how they could be *that* much weaker.

mike1324a

I think there is a market for them. Especially as time goes by and more and more people start seriously modifying their 8. If i was to seriously mod my engine i dont think that is unreasonable. Storker kits/Low compression pistons on other engines are in that area ore more expensive so it sounds like a good deal to me for any serious modders.

nycgps

iTrader: (1)

Well yea, as time goes by more and more people going to *seriously* modifiy their engine.

If something like this exist I will get it, at least I think its more *worth it* than RB's version

Theres a new item from RB

http://www.racingbeat.com/resultset....rtNumber=10047

Racing Rotor, but its more like they just sell it piece by piece

rotarygod

Please keep in mind that no one is building these right now and no one has even started it as a project. It's just an idea that has potential to go somewhere and we'll leave it at that. It's not saying it will though.

As to why 8.5:1, the basis of the new rotor design would be off of the 8.5:1 RX-7 rotors that were used from 86-88. These were the thickest and strongest rotors available. Yes they are slightly heavier but you'll only be using them for highly boosted applications and you'll never notice anything negative as a result of the slight weight increase. If they were light, they'd be weak. There's a tradeoff.

In reality they would be cast with no rotor dishes in them at all. The dishes would be cut out according to however they were ordered. They could be make at 8.5:1 or higher. Anywhere in there. It doesn't matter. Made to order. It would just be a simple programming change on the CNC machine. The rotors are actually thick enough that you could take it down as low as 7.5:1 if you wanted to. The strength will be there.

A downside of lower compression is less power off boost and lower gas mileage. But you'll be able to run more boost and make more power with the same octane level gasoline. There is always a tradeoff. As a general rule you should use the highest compression for the boost level and octane you intend to use. If you want 300 hp or less, stick to stock compression. If you want more power, start going down in compression. It's not to say that you can't make more power than this with higher compression. Not at all. It is understood though that your safety margin goes down should something go wrong.

Turbo spool is also slower with lower compression. You just can't get everything. People want fast spool, higher average power, high peak power, smooth idle, great gas mileage, emissions passing ability, good resistance to detonation, ability to use low octane fuel, etc. You can't have it all though so take your pick on which ones are most important. Chance are that if you really need more than 400 hp, you'll probably be willing to sacrifice some things.

While there have been many RX-7's that have broken the 400 rwhp mark with 9.0:1 compression, they don't really go much higher without running a very high octane fuel intended for racing or some form of auxiliary injection such as alcohol. There have been RX-7's that have topped 600 rwhp with 9.7:1 compression rotors. However it's been on C16 fuel or straight alcohol and not pump gas. With these fuels even a Renesis could probably go to 500 or so.

With 9.0:1 compression, you can get to about 425 rwhp or maybe a little higher on pump gas. At least in a 13B you can. Scott at Mazsport has been really showing that the Renesis has more in it than many people think it does and it is getting closer to this number and it is doing it with a full point higher compression. When you have a higher volumetrically efficient engine, it's not too hard to see why. If he can get near the 400 rwhp mark on a stock Renesis and pump gas, imagine how much higher it could go on pump gas and lower compression!

It's all a tradeoff. What is most important to you? IF anything ever happens with new rotors, you'll be able to decide what compression you want and will be able to get it.

RX8PDX

I need to convince the wife to let me get a turbo first, but if the funds were there, I would be interested also.

I think as the 8 gets more common, and people are seeing what its capable of compared to previous gen rotaries, I think the market will start increases more and more.

LiL BenNy

id def be interested when i blow my engine... lol it will either be this or an ls1? hehe

maxxdamigz

iTrader: (1)

As the turbo gets get more highly circulated and you start seeing more people popping thier engines on bad tunes, over boost, or just mileage, the replacement engine market should become pretty steady. Maybe Mazmart or whoever was starting up Renesis rebuilds over the winter would be interested in carrying a stock of lower compression rotors.