Ok so im in the planning stage of putting a 20B in the TII. the goal is 650 WHP, with as little boost as possible. I had very good luck with high compression/low boost on the 13B, and i'd like to go the same route with this engine. The major reason for this is that it is much more efficient, as BSFC decreases with compression, and increases with boost. also it gives a nicer power curve and a lower lag time.

I have not yet bought a 20B block, as i havent quite decided how i want to go, and since i need another month or so worth of spare cash to get a decent start on the project. fortunately toyota has me working a decent amount of overtime lately....

What I'm trying to decide is which rotors to use in my build. obviously I cant use the 9.4 s4 that i really like. I'd rather not use the 9.0, as thats a little low on compression in my book. so, my question is, are the 9.7s strong enough to handle this power level (i'd like to build for ~850 bhp, even tho im not going to run at that level) I've heard a lot about how weak the 9.7 rotors are, makes me nervous to put them in a medium boost engine.

also, if the 9.7s are no good, are the rx8 10.0s any stronger? and if so, is the thinner apex seal issue the only problem? they are the same weight, right?

getting away from rotors, is it any more economical to buy a blown 20B than a running one? and also, do the stock intake manifolds flow well, or should i plan on getting a short block and TIGing up my own?

no matter whether i buy a running one or not, this engine will be apart for bearing and oil mods and porting before it ever sees mounts, so getting a blown core is no issue. and also please hold the advice about how this swap will cost me more than my life and etc. I am fully aware of what i'm getting into, and I think most will be surprised when i post up my final price and benchmark.

thanks for helping a 20B newbie out, guys!

pat

PS if someone can point me to a link with the pros and cons and/or reviews of the different 3 rotor capable ems's, i'd appreciate it.

 

i dont suppose anyone has a junk s5 na rotor that they would send me so that i can cut it in half and compare casting thickness to the s4 na? (i will pay shipping, and share the info with this forum as well as the fc section....)

 

why not try the RX8 rotors..
didnt Xcessive do that with his FD with much luck?

 

Hi comp. rotors + boost = kaboom not Zoom Zoom

 

rx8 rotors are no good for peripheral port exhaust housings

 

yeah, im going with the 9.7s

GT1-20B, you have something to learn about how forced induction works. boost increases effective compression ratio. thats all it does. so if you start out with a higher static compression ratio, you can make the same power with less boost, and no other changes.
also, as far as stresses on the engine, there are actually more stresses from low compression/high boost setups, because the engine is making more thermodynamic power per actual HP output due to more power loss spinning the turbo.

engines with a higher compression ratio have a lower BSFC, so they require less fuel to make the same power. hence better economy and less heat to dissipate.

the only reason the high horsepower crowd is so into low compression these days is that its easier to tune a low compression engine. forced induction creates a relatively predictable fuel curve, where static compression doesnt, so tuning is a more careful thing.

pat

 

I made almost 600rwhp at 16psi on my 20b with fd rotors and my car was very responsive. I'm shooting for 600rwhp at 14.7psi this time around. I don't see any reason why thats not achievable and the engine is barely breaking a sweat with stock ports.

-Destin

 

I guess I do have something to learn:
After nearly 30 yrs. at the Pro-Levels of the Rotary world, once again, after a fair effort at passing on good advise. I'm reduced to realize : You can take a horse to water, but You can't make'm drink it !

With all this " Rotary Turbo Knowledge" You seem to posses, I ask ? why originate a thread asking for advise on CR's .....

Sorry if I ruffled Your feathers, Obviouly I didn't realize You have all the answers !

We'll sure be keeping an eye out for Ya' round the bone yards .

 

I posted under my roommates username, (sillbeer).

-Destin

 

I read almost every post in this section and I aint seen a cheap 20b swap yet. Youd be teh man if you could swap for cheap, specially if you tell every1 else how.

Bah I was all xcited til i read this. Dood how you gonna do all this swap if you dont even know how a ems works?

kaboom not Zoom Zoom?

 

^ Natural selection will get you one of these days...i hope.

 

I've had a 9.7 turbo engine build before. Wasn't that impressed with it. All else being equal between builds with fd rotors, the high comp engine bosted 200-300 rpm sooner had better low end response (not that I care because I am never in low rpm's ), made more power at the same boost but overall the engine made less hp and torque because I was not able to run as much boost, not even with water/methanol injection. The areas under the hp/tq curves were also less with the high comp engine when ran up to its limit on pump gas vs the fd rotor engine.

I don't think he know's who GT1-20b is

As far as the low end power/response with a high comp engine, that can be overcome with the extra rotor of the 20b.

 

This is a prime example of someone who is sold on their own believes and refuses to keep an open mind. In your first post you practically made it seem impossible to do such a modification. I guess Crispeed and a couple others here should stop successfully building hi compression turbo charged 13b rotary's that make over 600rwhp. If you have the experience ( that I believe that you do) then you know very well that it's all in the tuning.

 

They aren't with the stock Rx8 apex seals as they are shorter. To make them work, the rotors will need to be milled deeper for the older 2mm - 3mm designs. The engine will also need some balancing due to how much lighter the Rx8 rotors are. The 9.7 rotors weight exactly the same as the stock 20b 9.0 rotors. I'm currently going to build my 20b with 9.7 rotors for the same reasons. Better response with better power down low and more power at lower boost levels. 450rwhp at around 8-10 psi just sounds extremely nice.

 

my high comp engine blew due to torque twist breaking the dowel pin on the housing. had nothing to do with compression.

I know exactly how an EMS works, i just wanted some advice from those who have used the different ones. for example the haltech e6 is a pain in the *** to tune, where the lt8 is much easier and has better resolution. the kind of **** you dont know till you buy it.

As far as cost, I am budgeting $5-7k for this project.
Blown core: 2k
rebuild parts+balancing: 2.5k
EMS:1100
turbo: free (already got it)
exhaust manifold: 200 (money for bends, fab work done by me)
mounts: free (fabbed by me)
charge piping: free (re-fab my old ones)
oil pan: free
clutch: 100 for a stiffer PP for my 13b one
flywheel: already got it
100-500 for random crap i didnt think of.

$6k isnt exactly cheap, but its a lot less than the 15-20 that most people tell you youre gonna need, and i may be able to shave some of that, too.

i wasnt asking about the compression ratios, i was asking about the strength of the castings, since i dont have any of the rotors in question to examine myself

GT1-20B, i didnt mean to offend your intelligence, but if you were really just trying to help me out by posting an unproven comment about something unrelated to my question, then im not sure what to tell you. Maybe you should try adding some facts to back up your advice. Even if i had been unsure about that, just telling me that it will make my engine go kaboom isnt much help.

As far as the whole compression argument, I know not many agree with me, but when you have taken as many engineering and thermodynamics classes and built as many different kinds of engines as I have, you might see things differently. I will be glad to discuss it civilly with anyone who wants to provide some real information, rather than "well i had one once and i blew it up"

Pat

 

Hmmm...are you sure about this?

32 x 32
6.4uS
0.1-degrees

What does the Microtech do?

I'm not arguing about "easier" - I'm wondering about "better resolution"?


-Ted

 

Yeah but Crispeed and these others are not building high compression motors for the street. He has built high compression motors running on methanol for drag racing use only. Patman is building this motor for street use on pump gas. Besides that I'd rather go with lightened pair of 8.5 rotors and be able to run 20psi boost safely on pump gas. A pound of boost will have greater effect in making power over 1.2 more in compression ratio. And if he had any idea who GT1-20b is it would be well advised to ask his opinion. PM GT1-20b he is always willing to give out advice and help others.

"my high comp engine blew due to torque twist breaking the dowel pin on the housing. had nothing to do with compression." Patman

Torque twist breaking the dowel pin on the housing I doubt it. More like detonation and poor tuning. There are those making in excess of 600whp without added pins in their motors. Why don't they need extra dowell pins it's because they tune very very well. I have extra dowell pins in my motor simply because I am new to tuning and need that extra little insurance in case I screw things up. My suggestion low boost and most power I would go with bridge porting the motor or go with a semi-pport. You are going to lose fuel economy but hell you will make a shitload of horsepower on low boost. Good luck with your endeavor.

 

sorry ted, im full of it. lt8 16x16. dunno what i was thinking. the lt is more user friendly tho, and i believe the haltech lacks some of the teperature adjustment options and stuff. anyway, im no expert on which systems are set up how, thats why i asked about it. actually, I bet you could answer my question.

All who think broken dowel pins are due to detonation, consider this: detonation can't cause a torque in the forward direction, only in the reverse. the major forces caused by detonation are in the radial direction (straight out the side of the housing, like parallel to the spark plugs). How can a force in this direction break the dowel pin (well actually the rear iron casting) without damaging the rotor housing, or at least causeing a water leak? It cant. Anyway, dont you think I'd have heard detonation big enough to blow out a dowel pin? I didnt even notice that it was blown until i saw the smoke from oil coming out the hole it made. not to mention that it was cold, i was goin really fast (good airflow) and this wasnt the highest boost ive run. it was just the first time i kept traction enough to build the torqe that twisted the pin out.

The only reason i blew my engine is that i was too damn lazy to make some better motor mounts and a torque brace. when i pulled it out of the car, the right side mount was broken in half. had this not broken, i very much doubt that i'd have a problem.

pat

 

Dead wrong.
2lbs of boost is approximately equal to 1 point in the compression ratio, depending on the base ratio. that is, a 9.0 compression motor has appx. the same effective compression as an 8.0 on 2 lbs of boost.

the actual formula is:

Effective compression=static compression (9.7 or whatever) x (atmospheric pressure + boost pressure)/(atmospheric pressure)

for most cases, this works out to about 2lbs = 1 pt.

power output is very closely related to effective compression ratio, but also depends on temperatures and mechanical and thermodynamic efficiencies.

pat

 

Sorry to be a little vague in my explanation. What I was trying to get to is that how safely can you run a 9.7 compression rotors on pump gas? 14-17psi until you start worrying about detonation because of fuel octane. Where as there are those who have successfully pushed over 20psi boost on lower compression rotors with pump fuel. 8.5 rotors @ 20psi boost is going to make more power than 9.7 rotors at say 17psi boost. Well that's just my opinion and I'm just trying to help out with your request. I have a 13brew motor and using the stock rotors but have a set of 8.5 rotors that I will get lightened to '93 specs. Personally I like the casting's better on the S4 motors besides that I've seen the S5 and up rotor faces collapse. Good luck again.

 

Remember, were talking a 20b here. Some may need to run higher boost on a 13b with hi compression to make X amount of hp. I personally don't have any plans to run higher than 14psi on a hi compression 20b as my 20b will be tuned for pump gas and nothing else. Do you realize how much power I could actually make? Even at that range with a good size turbo would be too much for the street. Red-Rx7 made 628 rwhp with a t72 and 9.0 rotors at 13.7 psi. Imagine what he would have done with 9.7 rotors. That's the whole point here for me. Similar power with cooler charge temps and more bottom end with better response and better gas mileage. Imagine the around town drivability at even a lower boost say 8psi? IMHO this would be absolutely perfect.

 

..
This issue has been resolved.. with y GoopyApexSeals ,...
Try them on your next rebuild...on your next rebuild. .
wwww.GoopyApexSeals.com
845-947-0007
See our logo on www.pistonvsrotor.com..or visit our booth at the Pan American Rotary Vs Piston even in Salinas Puerto Rico Raceway Feb 25 and 26th. ..Oops Puerto Ricos Secret is out.
Buy them at

Delears:
*Puerto Rico:*
Mayol Speed Shop
Edificio M950
Carretera 149KM 9.2 Expresso a Manati
Manati Puerto Rico 00638
787-884-9044

*Florida USA Orlando:*
KiloRacing/RaceTech USA
Kilo or Carlos
9793 South Orange Blossom Trailway (OBT)
Orlando, Fl 32837
407-438-5467 or 321-229-6140

*Florida USA Tampa:*
New Import Speed Shop & Parts
Ramon Tossas
8000B N Armenia Ave
Tampa, FL 33604
813-936-3222

 

Pat i will say you are right about high compression + boost makeing more power. But to make more power it will take Higher octane fuel and make Det more likely to happen. For a street car i dont think high compression and boost will make a reliable car.

If you get a batch of bad gas it has a very high chance of causeing Sever det. And your probly saying well the same could happen with a low compression motor with high boost. Yes you will get some det but it wont be as sever.

If you are building this as a track day car or drag then go for the high comp and boost.. but if you are useing it as a street car i do think you will run into some problems. just my 02 and good luck with you build up

 

No offence taken, certainly not at my inteligence.
just an attempt to warn You of the inevitable.
As for adding facts to back up what I said, ..........I could sit here and take You to school on the subject, & bore you w/ information for countless hours on the Thermodynamics, & Combustion process of a Rotary engine, but I am sure it would be to no avail.
Already there are plenty of post from others advicing you to be objective, and focus on what is practical, and not on theoretical fantacies.
200 + reliable Hp. per rotor on pump gas & low boost "is" a fantacy.

To make 650+ Hp. out of a 20b, requires a fairly large compresor wheel, wich inharently brings mass & innercia with it. Also .......
The choke flow requirement of a ported 20b on a single turbo is quite large. At the very minimun, a 1.15 A/r .
Combine these 2 together, and You end up w/ a fairly large turbo that is inefficient at low boost . ....... Massive lag & feels like their's no turbo, while it spools up.
By the way, this is called surge, and happens when the air flow requirments are more than the compresor's minimum adiabatic efficiency in terms of CFM. at shaft speeds that define "Low Boost"
Larger Turbos like this don't respond, or flow well but rather "surge" under presure ratios of 1.15 or less, ruffly 17 psi.

Suddenly you will find your self with just the opposite of what You set out to build, the Turbo doesn't come in until Higher boost, at higher rev's and You have built your engine w/ Hi Cr. to boot

Your only logical alternative for this turbo is to CHOKE DOWN the Turbine housing in a poor attempt make quick boost, and end up with a Large Rotary engine governed to run at low Rev's

What fun is that ??

Some have made attempts at runing the twins on the 3 Rotor in an effort to reduce back presure and not limit the engine's Rev range, and yet retain good, low rpm boost, & throtle responce but in the end, been forced to face the music and admit falling way short of the target Hp.

Although what You've propose has been tried on street cars, You will find that turbo sizing for this purpose is a much easier task on a 2 Rotor engine. But in the end most frequently associated w/ eventual engine failure.


One last thing:
Believe what ever You may , and call it what ever you wish. But, this mis-conceived idea about tourque twist breaking the irons, in the real world is called pre-ignition.

Good Luck,

GT1-20b

 

you talk like you know all sorts of things, but nothing you just said has any real facts to back it up. go ahead, bore me with some thermo and some static force analysis, and explain to me how a radial force can cause a breakage in the tangential direction. And while you are at it, explain to me all about turbos, and prove me wrong when I say that turbo choice is based on pressure and mass flow rate, and therefore is not specific to engine displacement, but to the amount of airflow and horsepower desired.

pat

ps: and also, if youre going to lecture, at least take 30 seconds to check your spelling. all those misspelled words certainly dont lend anything to your arguments.