bigjoe25

Let me 1st say I know how to build "boinger" engines and Im not Jonny Ricer asking HoW d0 I mAkE da POWA wit a TUBRO!?@?!111

However, I will say this, I amm a complete NEWBIE when it comes to rotarys. I understand the reason behind lowering the compression ratio in a forced induction car because the boost will effective raise the comp ratio. Forgd internals are also needed to advoid detonation when it occurs so the engine doesn't go boom. I know knock because of detonation should be advoided at all costs, this I udnerstand. One way to do this is lower incomming temps and/or more fuel. All engines work that way.

Ok, so here is the million dollar question: Why cant I just turbo a N/A rotary? Im going to try to answer my own questions here a little bit.

1a. different Camshafts. A turbo spec cam is different than a N/A cam... Yeah sorry, I had to throw that in there, Im not that much of a complete newbie

1b. The computer is different. This can be remedied by a stand-alone ecu.

2. Lesser fuel pump/injectors. Even In a turbo model, I would upgrade.

3. Compression Ratio like I said above. Stock compression on a 2g 13b is 9.4. A turbo 2's is 8.5. How the hell do you change comp ratios in a rotary? Different Rotors? Would changing the rotors help? higher comp ratio will make a turbo spool faster in a "boinger" so running al little less PSI in a more effiecnt range turbo might be a good trade-off (think DMS, 8.5 in 1g with a 14b, 9.5 in a 2g with a t25, they are the same speed despite the vast turbo size difference.)

4. Strong internals. I hear Apex seals like to go, but thats true of them all. Of course I would go with heavy-duty ones if I rebuilt it. However, will a rotor "detonate" like a piston and fail? How are the rotors different in the turbo models?

5. tranny and rear-end. The turbo models are much mroe likely to have a stronger tranny, clutch, standard LSD, and gear ratios. However I would upgrade a stock T2's everything listed above so again, I dont see the problem.

6. Fuel. Pump to the injectors. Of course, I would upgrade either cars. (N/A or turbo)

Well that about sums it up for questions. Here is my plan. The only reason I am contemplating this vs buying a stock T2 is because I like to build my cars. I would be doing the exact same upgrade, the only difference is that I can put suporting mods on a stock turbo and it will be faster and cheaper than building a N/A, but in the long run the N/A upgrade to turbo specs would be just as fast. Im talking
Standalone ECU, fuel, clutch, LSD, t4 60-1 to name a few. I know whee to get msot of the parts and I've added it up.

Another reason is that T2's are rare. The closest one from me is 100 miles away and I REALLY dont want that one (it used to be owned by a friend, I do NOT want it as I know its problems) 2nd Closest one is 275+ miles away for to much $$$. Plus I can find cleaner, lower-mileage N/A's for cheaper. Plus it would be cheaper on insurance as well.

Anyway what are some of your guys thoguhs on this. I know it will cost more in the long run. Tell me the advantages and/or the disadvantages of doing it my way vs buying a stock t2 for $6,000 or more, or buying a N/A for $2500 or less and then turboing it for $5000 or so (including suport mods)

Any info on the RX7s would be aperichated really. A vendor list would be cool as well.

Attila the Fun

iTrader: (1)

Short answer: You can. Longer answer: It's re-inventing the wheel, and the newly re-invented wheel won't be as strong.

With care, you can turbo an N/A motor. It will actually have a small advantage in having more low-end torque, due to the 6-port design and higher compression. However, the advantage goes away and becomes a detriment as engine speed increases. Rather than go to all the trouble to rebuild an N/A motor to alter the compression ratio, it's easier and cheaper to just put in a T-II motor.

To answer your question more precisely: Yes, change the rotors OR have them machined. Machining them to change the compression ratio is costly, though

The rotor doesn't detonate (thought I have heard of them melting in cars where people made silly mistakes). The apex seals let go--like losing the piston rings in a boinger. "Heavy-duty" (3 millimeter) seals have not, to my knowledge, proven to be that much more reliable. The turbo rotors have a space machined in the face that lowers the compression.

To quote the Bard: "Aye, there's the rub." If you don't upgrade, you'll break. If you do upgrade everything else in the drivetrain, why not do the motor, as well?

That may be the deciding point, if you choose to ignore common sense. If you enjoy tinkering and don't need to have a more reliable car, you can do it for the fun of it. Just acknowledge that it's not the most efficient plan.

The first and most important issue is to define your goal(s). Then, tailor your plans to meet them. If your goal is just to tinker and learn, you can do the upgrade from an N/A. If your goal is to build a scary-fast car, get a series 5 T-II, then upgrade it.

SureShot

Rotary basics:
Compression ratio is determined strictly by the face shape of the rotor.

Pro:
No cam line with its friction, load, size, and weight penalty.
No valve heads & stems to impede flow.
All timing & flow issues are controlled by the shape & size of the ports. (5 per chamber on the Renesis)

The stroke (eccentric) is very short, so revs can go high and torque will be low & broad. You don't see a sharp torque peak.

Reciprocating mass is zero and rotating (balanced) mass is low.

Con:
The metal clearance angle behind the compression seal at the apex is ~60 degrees. (With a piston its 90)
This leaves less tolerance for detonation stress.

RETed

You're not just a complete newbie on rotary engines; you're also a newbie on how to efficiently use a public forum.

You see all the stickies at the top of EVERY page?
You should try and click them - you'd be amazed that your last question is actually answered in there...


-Ted

Icemark

Okay, so everything you know about piston engines, put on the back burner, because most are not the same for rotaries.

, again not applicable to rotary engines

... no just increasing fuel on a rotary will result in lower HP output.

. you can (please read the FAQ for FC sticky thread at the top of this section before posting).

, no cam shaft on a rotary... not sure if you understand this concept.

actually no, you would not want to upgrade until other upgrades have been done. The stock non turbo injectors are good for up to/around 50hp more, without modifications

no need to change compression ratio in the first place, but if you wanted too, you would just change the rotors. Now if you had a 89-91 non turbo, and were thinking about turbo'ng it, then I might change the rotors to a lower compression, but otherwise there is no need.

Detonation will damage Apex seals, but seldom damages the rotor. More likly is that damaged apex seals will damage the rotor and housings. As far as the difference in rotors between the Turbo and Non turbo, it is only the compression ratio that is different.

Yes they do, yes you probably should

again no, not unless there are sufficent other mods to justify it, you will only lower HP on a rotary by increasing fuel. This is not the same as for piston engines... more fuel does not increase output, unless breathing efficency is increased.

It sounds like you would be better off buying a Turbo, rather than trying to convert a non turbo, even if you did have to travel.

bigjoe25

Thanks to eveyone who has posted! Im not sure what my goals will be, I will b looking at everything from a broad view. Im leaning toward just buying a stock T2 to advoid head-aches in the future.

BTW thank you RETed, you post was the most inspirational out of the rest posted. You're insigt on my dilemma has proven most helpful and I beleive you carried this thread to completion. You are are great human being and deserve the nobel prize for literature. I would say peace as well, but that might already be taken.

Seriously though, at least other people comented on why it's not smart to turbo an N/A due to the fact of the drive-line will break and if I go to the hassle of upgrading the drive-line I might as well bought a t2 in the 1st place. If you don't have anything to contribute, why even post?

Turboing a rotarty is 100X easier than turboing a boinger. I have turboed a couple N/A cars with big sucess, one being a 240sx (ka24de) and the other being a friends Honda. The fiend didnt go with forged internals and still had higher comp and everything about his engine has failed and is not having the pwoer output like he wanted. My 240 had just a hair under 500 HP and the only reason I got rid of it was because someone offered me a price I couldn't refuse and a daily driver car to go with it.

If anything, I think Imight save up for a FD, but the weak Apex seals kinda scares me away. I could afford a new Rx8, but they have become more of a Grand touring car than a true sports car.

Jager

iTrader: (10)

Not too nice to rag on Ted, he adds alot to the forum and is a very helpful person.

Also you don't need forced induction for big HP. Actually you should of done you're homework before buying a NA over a TII. Impulse spender perhaps? I would think with the cash you make turboing every car and having a 500hp 240 would easily get you into a FD range (or something simular). And FYI, all cars with apex seals may break. Just the same as any piston engine can throw a rod ;o!

Now be nice

Icemark

what makes you think the apex seals are any weaker on a FD than a FC or any other rotary??? Now you do sound clueless.

obvously someone that has not driven one

Digi7ech

iTrader: (1)

Since you are asking these questions I do not recommend a Turbo conversion on an NA block.

You really need to know your 13b before you take on a project like that.

I would say a 13BT conversion would be easier than 13b/Turbo'd.

As well.
My only deterrant from turbo'ing NA blocks is that the Tuning/knowledge base for 13BT's are insanely huge compared to turbo NA's.

On a NA you will need to do lots of custom tuning to get it in runnning condition.
On a TII block you just throw an Rtek 1.7 ECU in with 720's and a boost controller and your set for a good 20+hp increase over stock.

RETed

Yeah, especially since Mazda lists the exact same part number for all apex seals from 1986 +.
Clueless?
I concur.
I think he should stick to piston engines.


-Ted

powrdby13B

well don't talk THAT much **** on the drivetrain for a 86-88 na... it's gonna take more than 250 HP to blow the tranny/rear end.. this i know is true...
if you decide to turbo the na, the tranny/rear end wil be the least of your worries

aaroncake.com or .net or whatever has a good guide... you'll find your internals don't need much help. YOu aren't putting any stress on internals compared to a piston where the rods/pistons are having to stop and go with each rotation. unless you're running REALLY high boost, the only way to kill your engine is to **** your timing up or lean out and detonate, and other similar situations

NZConvertible

What he said was completely correct, adding fuel to richen mixtures will suppress detonation in either a piston or rotary engine. It will also lower power output in either a piston or rotary engine.

Ooh, that attitude is a recipe for disaster. There is nothing about a rotary that makes it any easier to turbo than a piston engine. Apart from the obvious difference between the internal configurations, the basics of turbocharging an engine are exactly the same whether it's a rotary or piston. Both are 4-stroke internal combustion engines and pretty much all the induction/turbo/exhaust hardware bolted to the outside is the same. Sure there are differences in the details, but thinking that doing this is going to be 100 times easier that with a piston engine is just nuts.

A Supra is more of a GT car than a true sports car. An RX-8 is nothing like a Supra...

ddub

RX8 is a 4 door family sport coupe

Just my opinion

iceblue

Seeing we both have the same cars. I think the 8 is the best production track car other then C5 under 90k that I have ever drove. Underpowerd for its superior capabilitys but incredable car to drive on the track. A barrel of fun in my opinion!

ddub

Huh? Track car? Obviously you haven't pushed your rx8 very far then, because I must say in stock form it is VERY limited! My 2nd gen owns the hell out of it, even did before my coilovers/suspension upgrades!

In my 3rd week of owning my rx8 I took a normal 90º turn at about 20mph in 2nd gear, hit the gas a little during the turn and got shot completely sideways. Then a week ago with damp ground (not very wet and not raining at the time) I was taking a turn at a light and spun 180º and ended up facing some shocked drivers in the other lane.

It handles pretty well for a stock car, but far from a track car that's for sure.

iceblue

I can push it far greater then each FC I have owned and my miata. Out of evry car I have drove I just love it. Outside of the understeer that is in evry mazda I have drove lol. Yea wet rain kinda sucks. I down shifted to 2nd at 45mph to pass a car and changed lanes at same time. The entire time I passed the dood I was faceing into his door. Was a pain to get back in shape. TC kicked in and wheel was over one of the reflectors and that just screwd the whole situation up. But a perfectly balanced car none the less. 90o corners at 60mph all day long. Your punching when you shouldent causing rear end to come around on you.

ddub

Maybe, but I also don't have Traction Control. Traction control is for people that need the extra help, no offense

And 90º turns at 60mph? Sorry but I'm gonna have to say a big BS unless you are taking HUGE sweeps into the turn and taking them very wide.

And like I said my 2nd gen owns my rx8 at handling, of course my 2nd gen is far from a stock suspension, so it's a bit hard to compare the two. But I have yet to be able to lose traction when pushing my 2nd gen, rx8 has happened a few times now.

RETed

Have you driven an M3?
How about a Miata?
How about a Z3 or M-Coupe?


-Ted

ddub

That's a good point

iceblue

I drove the v8 M3 rodster at the honda delarship when my friend was the car joky :-) handled like *** was fast as *****! M3 coup no. Miata read my post below where I have one or my signature. Z3 and 4 I realy had no liking for them. :-/ maybe my driving style.

iceblue

I do make a effort to apexi evry corner I take. We will say taking 1.5lanes in and sweeping 2 lanes out I will have no dificulty making a 90o at 60 to 80 providing marginal conditions veriable. I generaly use the TC after all its there why not.

ddub

You may have TC there, I do not. I got an RX8 without that option

Same with DSC (dynamic stability control)

iceblue

It makes a big differ. Can push car further. I have taken "right on red" 90o corners at 40/45mph into far lane of 4lane devided. Car stays and makes corner only b/c of TC "atleast without sliding tail into median". I have the option and it adds alot to "dry" condition cornering I think. Yea got DSC too.

ddub

Meh, I didn't want any of that crap. I got a Base model rx8 with NO options other than what they all come with standard. I wanted the lightest, least amount of frills rx8 I could. Now my rx8 weighed in at 3005 in stock form, if I could get it down to 2900 I'd be content, but once you start adding a bunch of the stupid options it just keeps getting heavier.

NZConvertible

TC and DSC don't add weight, they're just software...