Which port is right for me?
 

I need to build a engine for my FD racecar. The car will be used for circuit work and drifting (dont hate me :lol:). I want to build an over the top engine that will handle way more than I could throw at it.

I want to make the widest power band I can, rev to 9000rpm, be making around 14psi by 3500rpm (4000 at the latest) and get as much power as possible without boosting past 25psi. Using pump 98RON fuel and water injection (no meth).

My current shopping list (subject to frequent change :lol:)
NRS Ceramic 2 piece 2mm Apex and solid corner seals.
2 piece center bearing eccentric shaft.
Turbonetics GT-K 1000 turbocharger.
Race stud kit
and many other things but you get the gist of it.

Now i'm new to both rotary engines and turbochargers. I've been doing as much research as I can over the last month or so and I believe I now have a fair understanding of what I'm getting into, but if i'm wrong about something please point it out.

Finally to the point of this thread. Given the ultimate goal what kind of port is right for me? Obviously emissions, noise and a nice idle are of little concern to me. I've been looking at a semi peripheral port with street side ports, would this suit me? or something else?

I forgot to mention that reliability is a concern, I don't want a port that will dramatically compromise the life of the seals or risk swallowing them.

Reliability with that much boost? Good luck :/

What breaks at 25psi? Oh and some friendly advice don't just make comments, give reasons to support your opinion. As it stands that post is not very useful to me.

If you are looking to make the most possible power at a certain PSI then a perihperal port or a semi-peripheral port would be the best. 25 psi would be easily attainable by 4000 rpm if not sooner, while making around 700rwhp... on pump gas with water injection.
however its not the most reliable setup.. but it doesn't mean its not streetable, it just means that it will need to be rebuild more often.

If you are making this much power you will be wanting to use a t6 turbo, with a completely custom exhaust manifold, and turbo manifold. It will also require a standalone ecu, just to list a few major upgrades.

If looking for reliability, you are more likely to get it with a streetport or a bridgeport. This engine will not last an extremely long time with any port. Streetports are also much quiter, getting louder and louder with the more extreme ports: bridge, semi-pp, pp..

you will still be able to make awesome power with these ports, they just wont yield the most possible power.

if you are going to say you want to build something like this, then you have to know what you are getting yourself into. I dont know if you are or not, just putting it out there.

I may have given mixed signals, I suppose maximum power is the least of my concerns. A wide, usable power band is more important. Would I really need a t6 turbo? You say this setup would need to be rebuilt more regularly. But why what is going to break and/or wear out? Would running only 20psi substantially change the reliability?

Hey man I wasn't trying to be a jerk, that's a lot of power and a lot of boost, with a lot of things to go wrong. Your primary issues are going to be cooling all the heat that the setup will generate, and the fact that a fuel hiccup at that boost level can detonate pretty easily and kaboom. Plus all the stress that that much power creates causes components all around to wear out at a faster rate. AFAIK the only kind of porting that directly affects reliability is a bridgeport, because the little bridge for the corner seal can fatigue and crack. Mazda used peripheral ports on their LeMans race cars (non turbo though) and over their history of participation had the highest finishing percentage of any manufacturer.

Good comments above.

It sounds like a good street port would fit your needs of wide power band. Balance the assembly so that 9k RPM is doable. Maybe do 3mm seals instead of 2mm for better detonation resistance - although I understand the NRS seals are quite resilient.

Less boost = more durability. Search on a thread from howard coleman in the 3rd gen section about AI / WI.

Check the Single Turbo section for dyno plots of various turbo setups so you get a better idea of your options.

You might be well served by speaking with a local Rotary shop and leveraging their expertise. It could save you some money.

the old apexi drift FD was running something like a small street port, their turbo kit, which is maybe gt35 sized, at around 15psi.

they were making 350-380hp

much more than that, and you are going to run out of room for radiators

Lets say you were looking for roughly 500rwhp. A Big streetport, along with a GTK850 (since you seem to be interested in the GTK lineup) will yield very strong response, with a pretty wide power band. You will need to get a big ol' radiator. If response is of concern, i would also look into using a V-mount intercooler, it will help with lag quite well. You are fine with 2mm seals at 9000rpm, as long as you clearance and balance your rotors. You will also need to look into a better fuel system.

The apexi Drift car ran the stock twin setup for a while before moving over the a small street port and the rx6 single turbo setup. They also used a vmount setup which I think should be used in a track/ drift car for best cooling

I think the first thing Andor needs to make a decision on is max power. That will give everyone a better idea of how to comment on a combination. Right now we are all shooting in the dark.

Also, a big street port will shift the power band, not extending it. What he needs to look on is his air flow characteristics eg. intake manifold, throttle body flow for range.

IMHO, I don't think you would need an rpm range to 9k if you want to spool and make power very quickly. The apexi car won titles and broke records, turning only 7200-7600 rpm while making 450hp peak power.

Jusy my .2 cents

Thanks for all the replies guys. I've always thought that shooting for a specific power is the wrong way to go about it. I want to make the most power I can whilst meeting my goals of powerband early boost and reliability. But to give you guys an idea I would be happy in the region of 550 - 650hp. The car will be built from the ground up and nothing will be unchanged. I believe I should be able to deal with the heat generated. For intercooling I will be using an water>air intercooler possibly with water spray on the heat exchanger. I want to rev to 9000rpm primarily for speed in a given gear, I don't mind if it is past peak power as long as it hasn't dropped too much.

I am a perfectionaist and I want to build this car once and get it right so I can just enjoy it. I built my last car 3 times and still wasn't happy. Cost isn't an issue. If it takes 2 years to build slowly as I can afford it then so be it.

Oh and my reason for looking at the GTK series is I want an inconel turbine wheel. I plan to make custom exhaust sleeves and I've read about melting turbine wheels :o

you see I think, thats where I think you might have trouble with the setup you want. I not sure their is anyone here making full boost by 3500 rpm with a 550-600whp setup around here. i could be wrong, but I personally don't know of anyone..... yet.

Also, spraying water on your heat exchanger while racing I don't think will be allowed. (water on the track).. not sure. I would check it out.

if cost isn't a issue, I think maybe going with a three rotor might give you everything your looking for. Enough motor to spool a big turbo quickly. I'm only speaking from a power point of view. I don;t know about cooling it though.

I never said full boost I said 1 bar by 3500 - 4000 rpm.

Water spray is a fine mist it is only on when needed (under boost) and is entirely evaporated.

I'm with Indian, if cost wasn't and issue for me, I'd be rocking an N/A PP 3 rotor. The Boys from Speedsource make about 450hp with their setup, and seeing it in person, it really doesn't look all that complex. Most Grand-Am teams use a Motec EMS to run it, so basically everything has already been done for you. Also running an N/A keeps you away from the crazy amount of heat that seems to plague the Turbo Rotarys. Plus, they just sound awesome at full song......

My most important concern for the whole car is getting the weight down as much as possible and keeping the balance, so 20b is out. Also i'm not interested in N/A.

I'm a machinist and I have a spare engine so I thought I might try something silly. Two peripheral ports per rotor, placed next to each other of around 30mm in size. No side ports. Compared to a single 2" peripheral port there would better velocity for low end stuff and less overlap. However flow would be approximately 25% less. Thoughts?

Your spool and power goals do not go hand in hand. Having a bar by such an rpm will be near impossible with the size of turbo you will need to run to achieve the hp you will be "satisfied" with. 400 would be possible with that kind of spool but you are limited to 7000-7500 rpm usually because of the turbo you'd use. I've seen 400hp out of a gt3076R which is relatively small. 1 bar by 3000 and 400whp at ~18psi. Remember that this is a small t3 turbo, and subsequently, turbine. To do something like this, you have to make sure you have plenty of wastegate to evacuate the gasses after the engine has reached desired boost. Be aware that fast spooling setups USUALLY (not always) generate a TON of heat in the engine and adjacent ancillary equipment ie: intake manifold, radiator, intercooler, turbo center section. Race fuel will be a must. Cooling system will have to be top notch.

I'm not saying your goals are COMPLETELY unrealistic, just extremely lofty.
That being said, if you are dead set on this then I welcome you to prove us all wrong. New ideas are always good to further experience and grow. I'm trying one of my own and will have some results hopefully before then end of the year.

I forgot about another thing.
Using large/high overlap ports such as peripheral will yield a ton of flow, but poor low rpm volumetric efficiency because of the nature of the high over lap. Just because you have a lot of boost at 3000 rpm doesn't mean you'll make more power than one with smaller ports and less overlap at the same rpm. Port shape not size, will be the determining factor in the powerband of this engine. Something close to stock with worked ports (reshaped, not made larger) will yield a good powerband from 3000-7000 usually.

Look for peripheral port turbo dyno's and you'll see what I mean about the bottom end.
torque curve doesn't always reflect boost curve on high rpm high overlap engines.

1. my FC only lost 40lbs going from a stock turbo 20b to a 13bt.

2. what would the advantage of 2 PP's be over one? the NSU engines did something kind of like this, they have a teeny tiny PP that is timed for no overlap, and hooked right up to the primary barrel of the carb. second port is bigger, and earlier hooked right to the secondary of the carb. idle isnt any better than the std mazda PP (it might be worse, actually, i have seen one running)

A machined perihperal port is the way to go if you're looking for boost that soon in the RPM range. Thats why i am doing one. You'll want to have pretty small ports though if you want your system to be optomized at 650hp. Im pretty sure with a BW s475 you'll see around that much power at 1 bar, and you'll probably see it at around 4000 rpm as well.. your powerband wont be the most friendly, but you'll whoop ass with it.