j9fd3s

iTrader: (3)

its funny cause ive heard about this engine from a couple of other people, and everyones seen old pics of it.

shm21284

Then where are they? Give me a link, a dyno graph, a video, something. Like Roen said, everyone else's power is right around the high 100 wheel hp to the low 200 wheel hp. This guy made turbo power with side ports? I just don't see how its possible. What was the peak torque value? What rpm was it generated at?? There are so many unanswered questions here. I just don't buy it.

peejay

It wouldn't happen to be in the Racing Beat catalog, would it?

Oh, I know. Perhaps a certain E-Prod engine that was built with all the "trix" you could put in a "Mazda"? (Ahem) That would be my fairest guess. I don't think he ever released power figures but I do remember hearing about the way the engine kept making power up to the point where they honestly didn't want to run it that high any more, AKA 10k+, and specifics about where peak torque happened.

THAT one, I can believe 290 at the crank, not wheel horsepower. For one, all tuning for THAT engine was done on an engine dyno...


Also: https://www.rx7club.com/forum/showth...2A#post1354471

Tom93R1

iTrader: (2)

Its not the Racing Beat motor, I know that much. Do you know who 2a+ron's works for? That might be a hint if you want to look for info on it. Damn I wish I know what info he does or does not want out there.

j9fd3s

iTrader: (3)

similar setup, they have raced that engine, although i think they had problems making it and the trans live @10k.

George84

Back in the summer of 2005 my max whp was a 151.13 whp at 7600rpm on a Dynojet. My running conditions were 102.20 *F, 29.70 in-Hg, Humidity: 21%. I was hoping for more but they only got a 5 or 6 rwhp gain out of the S-AFC II. This is on stock ports. I was not very happy with the shop I went to at that time. I am going to get re-dyno tuned on 4/3/08 at Tuxedo Park Racing, I am sure they can pull a few more hp out of her with a good tune and it won't be near so hot outside. I will post what my new numbers are after I get re-tuned.

ryanvx

iTrader: (1)

Bridge ports are ****... period. Large street ports still yield more power. Don't waste your time or your iron's on that route.

Rx7_Nut13B

iTrader: (1)

Sorry to pop your bubble......

Running NA Bridge ports will still kill any street ports.

Now running a Turbo, street ports are better to a certain point then Bridge ports take over.

And I am not saying the street ports are bad at all...... Just to make that clean... They have there place in the Hp world.

BLUE TII

iTrader: (9)

Rotarygod on the renisis-
So, since we have seen that 4 port 13b NAs make more power in "race" trim than 6 ports (several dynoed in the 200+ RWHP range) has anyone else thought about using the 4 port renisis as the base of a performance build?

ultimatejay

iTrader: (1)

NOOB. stockport<streetport<bridgeport<peripheral port.

pirsq

e-prod scca legal 2nd gen Pi pipe test car has made 204whp (mustang dyno)at 9200 still rising on a un-clearanced motor(same car test 20hp higher on dyno jet dyno's so 224whp dynojet) 1st gen 38 choke 48 weber 191whp and still rising at 10300 also owner rev limited (un-clearanced)motor is apart rotor's going to roger mandiville for clearancing and rebalance 11k here we come (p.s. going electronic mapable ignitinon.... timing change was 5-7 whp with the pipe and timing split was worth 5-9 more on the 2nd gen)plus a 51 carb next......then the header test.....looking for a 1st gen legal 38 choke to try and make 210-215whp with all of the trix's in that one. we might try the bigger port from the first gen in the second gen next....? maybe 240whp(dynojet) might be possible?....unlimited intake itb's custom intake .... no rule's i think i can put down 250-260whp 6-port .....my exhaust though very effective test at 98db at the track a little loud for street use....you might get away with it with a slightly bigger muffler(walker race magnum welded 3" in out) will post new figure's when car is back together

Whizbang

the only part about this is the variance of the dyno. The type of dyno alone with generate different results and significant ones at that. Plus you can mess with settings on loadings and corrections and the like. I really think think this would be hard to make official without all the contenders running at the same place, on the same dyno, consecutively.

rotarygod

iTrader: (1)

The problem with the 4 port Renesis housings is that their ports aren't like 4 port 13B's. They are more closely related to 6 port engines but without the aux ports. The secondaries are small. They are only open 10 degrees longer than the secondaries on the 6 port engines. The primary ports and the exhaust ports are smaller on the 4 port than the 6 port Renesis engines. I don't see as much total potential on the 4 port engines compared to the 6 port engines.

We are ultimately battling one thing and that is displacement. A small engine is physically limited in how much torque it can produce based on it's size as well as efficiency. Keep in mind that if efficiency is maxed out at 100%, your limiting factor is now displacement. Any engine can only prodcue so much torque. Now since torque theoretically would be flat across the rpm range as rpms rise (assuming 100% efficiency everywhere which isn't going to happen), horsepower would rise. This would mean we have 2 options to making more horsepower. One is to rev it up higher. Torque doesn't have to rise but as rpms do, horsepower will all things being equal of course. The other option is to increase torque everywhere and hence horsepower. To do this we need to increase efficiency. This is the reason for more agressive porting. A downside to this is that if you increase efficiency at one load and or rpm, you also decrease it at another. If we get agressive porting that keeps volumetric efficiency over 100%, and this is possible, power goes up at this spot.

As an example, a side ported engine is really limited to somewhere around 160 ft lbs of torque. Give or take a few but for example's sake, I'll use that number. Let's assume that we could in fact get 160 ft lbs of torque across our entire rpm range. It has typically fallen off quite a bit by this point though but let's just keep the example. At 8000 rpm, 160 ft lbs translates to 243 hp. At 9000 rpm it translates to 274 hp. If you max out torque potential, you can only gain power by revving higher.

However let's say we have a peripheral port engine that has a greater than 100% volumetric efficiency in places. Let's say we found a way to make our engine have 200 ft lbs of torque at 8000 rpm through this VE increase. Power at this location would now be a staggering 304 hp! At 9000 rpm with 200 ft lbs or torque, we'd have 342 hp!

Displacement determines total torque potential and hence horsepower potential obviously taking into consideration design goals. Porting changes the VE to give us more "usable displacement" by increasing VE over 100%. You don't have to have huge overlap to get 100% VE. It's all about the design of the total system. Hopefully none of that was too confusing. I imaging it'll raise more questions though.

pirsq

good post rotary god
you make a good point that most people dont take in to account all dynos measure torque...... hp is calculated......... the higher the torque the higher the hp the down fall of most rotarys is they make great hp at high rpm's but low torque. by increasing the torque across the power band we can make a big jump in power .... this is were my PI pipe comes in it raises and significantly flattens the torque curve.... where most rotarys peak and start to fall off this thing just keeps going and it shows up both in the torque and hp curves in a plateau shaped dyno graph.all cars tested start to peak at 7-7200 (pre pipe was between 8-8400 followed by a drop off about 3-400rpm later)and carry almost flat(the peak gain only increase's slightly after that)to 10,300 max dyno tested so far(customer did try it to 11k at the track said it pulled strait though like it wanted to go to 12k)
what i feel my pipe accomplishes though a dramatic increase in exhaust scavanging is a dramatic reduction in dilution of the incoming intake charge (much like the side port exhaust creates in the renisis)thus the increase in hp and tourqe across the board.as for a side port 290whp i would have to see it maybe crank? my friends scca gt2 car pp fuel injected is making 295whp(shooting for 300+for late this year)is a 2 time run offs competitor 1st year went from 20+ to 8 in 2 laps right behind patton in the sunbeam and snaped the drive shaft
and thats a stupidly fast car so if you know some one that can really build a side port to make that kind of power please email me contact info ill have guys lining up to give him or her buisness....hey combine that motor with my exhaust and we could rule the world....hahahahahaha

peejay

But it isn't, at least not volumetric efficiency.

Bone stock as-produced piston engines of the late 80's were doing over 100% VE at peak torque. And they're better all the time.

Side port engines would be lucky to approach 90%.

dj55b

iTrader: (2)

I'm really interested in hearing more about your exhaust setup. Do you make any for a 12a engine? Pictures would be awesome.

rotarygod

iTrader: (1)

It's not uncommon to hit 100% VE or greater on engines. They just do it over a very short rpm range and only at full load. In some cases they hit it at a couple of points rather than over a range. The RX-8 hits greater than 100% VE in 2 places in the powerband and averages over 90% for much of the usable powerband. That's why that engine with the same displacement as a 13B will walk all over it all day every day. It's a superior engine design in the same sized package.

VE is not a constant with rpm (or load for that matter). The goal of porting is to increase VE over a certain area that you intend to use. Ultimately though you can only get so much naturally aspirated and anything over 100% VE is over a small area. You just won't see 125% VE n/a like you can with forced induction. You could see 105% in places though and maybe a bit more. You get the idea. Ultimately the limiting factor is displacement and we just don't have much which means that we need to also consider rpm.

In regards to the highest n/a power challenge, porting isn't going to be the only thing that helps get the highest number and more overlap is not always (always being the key word) best for power. The engine that does get the highest number will probably be revving higher too and of course have everything else designed around this. Ultimately as long as everyone is using a 13B based 2 rotor engine, everyone has the exact same 2 things to consider in engine design. Since displacement is the same, that leaves highest VE through good porting (and again more isn't always better) and rpm range. Those are the 2 important things to consider.

In my example above I mentioned a theoretical engine that makes 200 ft lbs of torque at 9000 rpm making 304 hp. If we couldn't get the VE to accomplish 200 ft lbs but we could hold 160 ft lbs into higher rpms then we'd need to raise rpm to get the same horsepower. At 160 ft lbs of torque, to get 304 hp, we'd need to rev to 10,000 rpm. VE and rpm are the 2 things to think about.

yomo

too much tech talk

im getting lost


i'll just hope im able to pull 190~200whp outa my 13b when i'm done...





and a side question, the general concensus seems to be that the s5 9.7:1 rotors dont provide much of a boost in power. but from what you said, their ability to rev higher will then provide a higher power (provided its still making power)... .right?

so basic question is, is it worth it for an s4 owner going with a SP to upgrade to the s5 rotors?

rotarygod

iTrader: (1)

I have a Mazda chart somewhere that shows that compression ratios between 9:1 and 11:1 on a rotary don't really have much difference in power. I'd still personally like to use the 9.7:1 rotors though. If for no other reason, they are lighter than the 9.4:1 rotors and that's less power being wasted to turning weight. A light flywheel will also help you get more of the power to the ground as it's less loss in the drivetrain. If you have access to the 9.7:1 rotors, use them. Use the S5 intake manifold over the S4 also but keep VDI and the aux ports working. It will hold power higher up in rpms and not sacrifice anywhere else to get it. It's just a better manifold whether stock or street ported.

If your intake and exhaust aren't tuned to a higher rpm, there comes a point where revving the engine higher won't do you any good. Once your power starts coming back down, more rpms above that won't help you.

Whizbang

who even makes flywheels for these cars that are good enough for 10,000 plus rpm ranges? let alone clutches and pressure plates? I for one like my legs.

rotarygod

iTrader: (1)

I personally don't see any reason to take a street car over 9000 rpm ever. I'm just stating examples of how things work and nothing more.

Black91n/a

Not exactly, a brake dyno measures torque and calculates hp, an inertia dyno (dynojet) measures hp and calculates torque.

pirsq

a dyno jet works my having a known fixed wiegh i.e. the drum and then measuring the rate of accelleration i.e work over distance that is the measurement of tourqe it calculates the hp thats why the dyno needs a rpm input for the car being tested if you change the rpm calibration you hp will be wrong....trust me i had a dyno jet in my shop for years the first thing you make sure is correct is the rpm calibration or your dyno figures will be wrong

yes the pipe works on 12a's my cousin also races e-p when he saw the results from the first car he had me make one for him his original motor was a no port work ita stock virgin with 48 ida and made over 145+whp
the car now has a small street port close ratio box and tilton clutch flywheel set up as soon as it get some break in time we will be going to the dyno for more tunning and testing shooting for 160+ whp range
i will be doing the port work for the second motor which will be getting a more radical port maybe clipped rotors and a few other trix like a 51mm carb and programable ignition to shoot for 175+ whp

we may do some testing on a stock ita/it7 type car if we can get / make jets to get the stock niki carb to work the jetting and timming setting are critical to get the most out of the pipe and not cook the motor in the process

i dont like posting pictures because i dont like peope trying to reverse engineer stuff i have worked so hard to develope but that being said i got some more parts in and am currently building anoughter pipe and i will be selling them so if you run ita/it7/its/e-prod/gt3/gt2 drop me a line i am ready and willing to work with racers that want to make use of this piece an i will provide tech suport for it ....... trust me you will need it as all convetional ideas on rotary tunning go in the trash bin with this one everything is different

boyrotor

Oh nooooo... I have been watching this thread with anticipation for pirsq to put us out of our misery and expand on this magical 'Pi pipe'!

But fair enough you dont want to put pics up, but would you be willing to expand a just a little bit on what exactly it is and how it works? What does Pi stand for?

I understand if you dont want to being in the industry but it would be much appreciated by the rotary community - I promise!


And from what i understand you can use weber fuel jets in nikkis. Havent done it personally though so cant say for sure, just a tip.

BLUE TII

iTrader: (9)

Lol, somebody probably just rediscovered the use of a megaphone after the header collector :P