dial8

iTrader: (4)

Hey guys, lately I've been following the thread below by phillipthompkins and asking A. Cake, Rot. Ress. and a few others about high revving, high comp turbos. I did a little searching on the forum and and on the web and couldn't really a definative answer so I decided to ask the Gurus here in the Performance section.

1. How do you make a rotary rev up to 10 grand and make power up there?
I've seen arguments from porting and fuel mods to just balancing the rotating assembly and tweaking the ecu. I want to know how to make power that high in any rotary engine, Turbo and N/A, from S3 to S6.

2. How much benifit do 9.7.1 S5 N/A rotors really give in a turbo application? And whats the highest you would boost 9.7.1?
Is 10lbs too much? 15lbs too much? High comp turbo piston engines are super fast, but blow up really soon. On rotaries a high-comp turbo will spool the turbo faster and have better off boost response, but does raising the bar from 9.0 to 9.7 actually cause more problems in the long run as the higher you rev and higher you boost, the more you need to retard the timing to stay safe and the more you need to have a car in "perfect" running condition.

3. Mega single port top end, or bridge port top end?
Again with a turbo application where top end is key, is the large "mega-port", both intake ports milled into one large port, worth it or should you just go bridge?

My goal is a car that can compete in the Redline Time Attack and similar events and still fall under the Street Class. For those unfamiliar, the basics of street is unlimited engine mods as long as the car can still hold a valid registration and be driven on the street. I want to build a car with a massive top end, that can still be (rarely) driven on the street in between Time Attack, HPDE, and solo-practice. My power goals aren't lofty, but I would like something that make efficient use of its power, and doesn't run rich just so it wont blow up. I would appreciate any info from anyone, drag, Auto-X, and road racing alike, as anyone who knows how to make power has relevant experience.

fidelity101

iTrader: (11)

well if your going be going after a project like that you should not skimp out on any penny for an engine management system along with some good tuning.

and for those rules for a street car, does that mean you have to keep your cats? that would suck.

dial8

iTrader: (4)

I don't have to keep the cats, just show a valid registration. I am limited to the number of guages though, which I think sucks...

I plan on getting a Haltech, haven't decided which version yet. NOTHING will be skimped on and I want to go to extremes with everything, but still follow the rules. My problem is how to make it all work.

diabolical1

iTrader: (3)

1.) sufficient airflow - which essentially amounts to a port that will provide the engine with air up there. you'll probably want to look hard at a full bridge. streetports can rev there if they are large enough, but i honestly don't know how much power they're making as compared to bridges and peripherals.

2.) quicker spool is the only benefit that the high-comp rotors would give to you, but you'll also need to get you turbo, wastegate and wastegate runner setups spot on - even moreso than usual. you can run serious boost on the 9.7:1 rotors as long as you have the support - engine management, fuel, intercooling and a "good" (not decent) tuner.

3.) my experiences with the siamese ports (or "mega"-port as you call it) are limited to normally aspirated applications, but from what i read, they are not optimal for turbos - which is not to say it wouldn't work well, but it's just better to have the 4-port plates ported appropriately.

oveall ... from what you've asked, i'd say look into setting up a bridgeport turbo - maybe a 40R or 42R. there are several guys on the board running comparable setups, so search and see if you'll be able to finance a setup like that.

hope that helps.

diabolical1

iTrader: (3)

as for the legally registered part, which i forgot to equate into my previous diatribe - depending on where you live, you may be better off going with the siamese port and more appropriate turbo.

killahrx7

the most boost i've run on 9.7:1 is 22lbs with 10 deg. of timing WOLF3D EMS race gas. street port with holset hx55 turbo. car made power all the way to redline 8500 and did not fall off. like the guy said bridgeport makes alot of power upstairs so you can try a four port bridge. i've done 6 port bridge and loved it more than any other combinations. what you also want to look into also is the turbine housing a/r ratio. i think that also plays a part in top end speed. too responsive/small might choke the car up top, too large might produce alot of lag.

dial8

iTrader: (4)

Fantastic, thanks guys.

Roen

iTrader: (2)

A couple of people are trying 1/3 bridge turbos on a six port engine......though I think it would be interesting if someone tried a 2/3 bridge turbo.

dial8

iTrader: (4)

Call me crazy, but for engine thats being built to be beat on, I still have to toss that red "reliability" flag into play. Thats one reason why I chose high-comp, high power with less boost. The biggest thing I'm worried about/wondering about is making power up top. Most of the cars I've watched have anything between 350-450 WHP, in street class few people build their cars. 90% are newer cars with a ton of bolt ons, and 7200 RPM shifting points.

My original turbo plane for the car was a BNR stage one at 10 lbs. With port work, and supporting mods with a good tune that should see me right at 300 WHP at 8.2K and(I hope) 320 at 9.2. That will give some room to improve while I think staying on the safe side based on my forum reading.

Roen

iTrader: (2)

I think Aaron Cake has 391 on his 1/3rd bridge?

dial8

iTrader: (4)

True, and I thought he was only running thirteen pounds. But when I asked him he saw no point in building in a high rev motor because he drives on the street. He's shifting at 7K I believe, and hes happy. Which brings me to my next question, you can build an NA motor to make power at 9K, but will a turbo engine built the same way make power up there? The only theories I have on this are for piston cars, which just gives me a general idea, but nothing to really base my opinions on. I think the tune is key here so the engine doesn't out breath the turbo at the top end, or lag like a Subaru at the low end.

Roen

iTrader: (2)

I believe to make a turbo engine high-revving, you need to make sure that both the engine and the turbo don't run out of breath up top. You can build your motor the same way you build an NA, but you need to also pick a turbo that doesn't choke up top, or choke slightly, but still give you close to max airflow at the power peak rpm that you want.

dial8

iTrader: (4)

Cool.

So to cliff so far-
For this build I will need a port larger than a street port. We discussed what it takes to get an engine to breathe at high RPM and the most effective and efficient and way is to have a large port opening that just barely starts to scavenge from the low end to add to the top end. It is possible to build a turbo engine that will still go that high and make power, but turbo selection is key.
The 9.7.1 S5 n/a rotors are okay to use in a turbo application. Aside from giving little budge room in tuning and having a sharper power curve than 9.0.1 and 8.5.1 rotors, they can still be used up to 22lbs, which is way higher than I want to go. Everything has to be perfect, but perfection will also go a long way to preservation which is another plus.
I'm not crazy for dreaming this, it actually might work. +1 for the creativity of the Rotary Engine builders. I think the near infinite amount of set ups is why our engines will never go away.

Roen

iTrader: (2)

Personally, since I like to be unique, this is what I would consider:

6 port NA engine with the largest streetport you can do on the primaries, bridge on the secondaries and auxillaries
GT35R with a very very large exhaust hotside
Some unweidedly large wastegate with a 8 or 10 psi wastegate spring
A nice v-mount intercooler setup (Front mount if you want to spend less money)
Haltech E8 with analog **** for boost control
2 x 720 primaries
2 x 1600 secondaries
RP's Nippondenso Fuel Pump
Rising Rate FPR
Hell, Parallel fuel line conversion if you have the money
Make sure that Pulsation Dampener is good, or at least put a Banjo Bolt in if you have an S4
Maybe run NGK Iridium 8's in the leading and 9's in the trailing, with some nice Racing Beat wires
You could always lighten up the rotors to help them spin higher, as well as rebalance the rotating assembly with tighter tolerances.
Add a carbon fibre driveshaft and a lightweight aluminum flywheel, and you'll have something nice and rev-happy.

I'm sure I can come up with some other stuff later.

Black91n/a

The stresses and costs go up a lot as you increase the redline. On a turbo motor you're probably better off keeping a lower redline and upping the boost a little to compensate.

To really rev it out you need to consider lighter apex seals (ceramic, mega $$), lightened rotors, clearanced rotor tips, higher oil pressure, looser bearing clearances with race bearings, lots of oil mods like the loop line and oil pump porting, things like rotor gear retention, and lots of other stuff like that. All in all it'll cost more and be less reliable if you insist on revving it that high.

Roen

iTrader: (2)

mmm...Ianetti apex seals....what were they, $1500 a set of 6?

dial8

iTrader: (4)

Sneaky. The on thing I'm worried about in making it rev high is stress, though there are many ways to ease this tension. But a lot of people around me are asking if I really need to rev that high with a turbo. I still say yes, but are there any thoughts?

dial8

iTrader: (4)

The V mount I wouldn't go with cause it screams cutting, time, and hard ship trying to get everything to fit behind a stock S4 bumper. And I don't know if I'd go that high with the secondaries or turbo, since the most I'll run would be about 100 octane. Everything else looks good, but I can't give away all my secrets.

Roen

iTrader: (2)

You don't NEED to rev that high with a turbo, it's more for, "look at what I can do!"

dial8

iTrader: (4)

Kind of. My logic behind wanting to rev high is this. Two cars with the same HP, one shifts at 8K one shifts at 9K. The 9K shifting car will be "faster" because it shifts later, and shifting later means higher peak hp. Side by side the 8k will reach its peak sooner and the pause at the shift will allow the 9K shifting car to go farther/faster.







Did I **** that one up?

Roen

iTrader: (2)

If that's all you're looking for, you can just change your trans gears or your final drive to be longer.

dial8

iTrader: (4)

Hmm. I already bought the RB 4.30 gears and was hoping to have the best of both worlds. Is this the unrealistic part of the build?

Roen

iTrader: (2)

well, with the 4.3, you'll make the time in each gear even shorter, detracting from your goals.

The tradeoff is time in each gear vs. acceleration. The longer you are in each gear, the slower you pull.

Then again, all gearing does at the end of the day, is to set your accel characteristics as well as your top speed.

Our cars are geared way too high (think 200+ mph NA), so you can a significantly higher gear and still not top out.

I don't think the ITS guys running 5.12 gears are running out of gear, though I could be mistaken.

darkphantom

iTrader: (2)

anything is possible with the right amount of money!

classicauto

iTrader: (3)

Yep.

The reality is even with all the mods under the sun to keep the keg in one piece.....revving to the sky will make shorten the engine's life.

9K is really not that high though. As Black91n/a has stated you'll need a few key items but for only 9K it should hold up well with a proper build. ****, you won't even *need* a rated flywheel or scattershield at those revs, although it wouldn't be a bad idea if you value your legs.

Really though, if you plan on turboing the car, building it for a lofty redline is essentially a waste of time. Mainly because in order to size a turbo to actually breathe high up like that, you will have zero bottom end. If its a race engine then, hey I guess it doesn't matter, but at that point you may as well go with a cheaper build (to the tune of 3-4K cheaper) and have 1500rpm less up top, all while making the same amount of power as the high revving setup.