F1Pilot

Gday guys,



First post on here.



I have posted a fair bit over on FDRX7 in aus, but would like to throw what Im doing out there as much as possible to get some feedback on my ideas.



My FD is a 97 Series 7 RS. I originally changed to single turbo GT35, PFC, W2A blah blah, however the rebuilt block I bought from a rotary shop didnt last much past 1000k. It had not even produced any power yet and I was babying it alot.



Anyways, pulling that motor out has prompted me to do something Ive always wanted to, 20B!!



Having raced sports sedans in the early 2000's and driven a 13B PP in my old RX4, I wanted this motor to be NA.



For this, I bought a B series engine and pulled it down. All the internals have been sent to Xtreme Rotaries here in aus.



They will be lightening and balancing it and also some porting.



Now, onto porting.....my original plan was to go full BP with a custom designed 6 runner throttle body and manifold. I will be making my own carbon fibre trumpets too. I used to make similar setups for some IPRA cars here in aus.



I have designed the throttle body to be able to run primaries and secondaries. The linkages are adjustable and can also run all throttles at the same time.



After seeing Logans awesome results with his semi-pp, I began to head that way. Still keeping the BP and adding small semi PP. (Judge ITO, please chime in at anytime!!!!)



However, I will be making the manifold myself, and mucking around with Autocad it became apparent that it would be MUCH easier to run a full PP as a secondary.



So what I am thinking now is a BP primary, running off 40mm throttles and a PP, runner size is 45mm however I was thinking of tapering down to a 40mm PP in the PP sleeve.



i was thinking to not go too big.



I have attached some pics of the concept so far. Throttle bodies and carbon trumpet tools are just about to be machined.













So the big questions I have:



1. What would be better? full BP/semi-pp or primary BP secodary full PP?



2. If a full PP is better, do you think 40mm port area is too big?



3. I am looking to have the housings machined to take a PP sleeve I will design, however I am stuck on the timing. Should I try to time the port to open equally and close equally around the BP the Xtreme does? Something like this pic below:





Green would be the BP timing, Red would be the PP.



Im all ears and I hope to have this thing up and running within the next couple of months!!



Cheers.

F1Pilot

Also I have just realised that BP only on the primary ports, would allow me to run a 2 piece seal if i wanted to.



The plan was to try this setup on my old housings, which arent perfect and then if all is good, buy some new housings, port them and buy ceramics. Being street driven, I imagine the 2 piece would be better.

F1Pilot

I think my mind is made up on purchasing the LINK G4 Extreme for this job. It seems to so everything I need and more.



I will be looking at running 3 X 550 primaries and 3 x 1000cc in the standoff position on the secodaries.



The LINK can not only stage the injection, but allows you to allocate how much % of fuel you want from primaries vs secodaries. This is handy for me because I would like the standoff injectors to do most of the work at WOT.



Also anyone out there have any suggestion as to the PP size/timing questions?

shainiac

There are tons of options on port timing. The only ports you're ever going to get credible and documented information on is the factory stuff. SAE 900032 is a good resource.



Mazda used two different modern port timings. The "optimized" being the newest, but peakiest. Made more power, but less broad, iirc.



base optimized

IO 100 BTDC 80 BTDC

IC 75 ABDC 80 ABDC

Liborek

While this is true, we must point out that port area both on intake and exhaust side is substantially bigger, which in its own contributes to peaky powerband. I like the fact, that they worked out intake opening and exhaust closing timing with regards to how rotor face is physically blocking the flow path during overlap.

To the OP, honestly, you´re making it to complicated. Bridgeports are not worth a hassle. They have huge amount of timing without flow of semi-pp. Always remember why they were developed, to circumvent the rules after peripheral ports were banned in some race applications. I know that IPRA guys developed these things to limit, but same amount of development and money poured into PP - it wouldn´t be even comparable...

In my opinion, you should leave side ports with low overlap ie streetport at max + semi-pp. Or just do full peripheral port engine, based on optimized timing. Quality ECU and good tuning will take care of driveability. On the other hand, driveability of engine with to much timing and to much port area will be bad. Also tuning exhaust system to match everything would be huge pain, maybe impossible to do...

F1Pilot

Well I am now actually waiting to hear back from Xtreme to see whether it will infact be better to only extend port the primaries.
The reason I have swung towards a larger PP is the simplicity of the manifold over the semi-pp.

The throttle body is already being made, so it will be 3x40mm and 3x45mm intake.
However to make it simpler from here, would be to use the 45mm runners for the PP, (albeit the PP sleeve may reduce to a smaller size at the housing face).

I already have all the linkages made to be able to play with staged throttles, although it may infact do nothing.
The problem is that everyone out there seems to say "Im going to do this or that", and never end up trying it, nor sharing any actual results.

At least this way, I will know! Although the PP timing will be there, I am interested to see what it drives like and sounds like, when the secondaries are closed.

Liborek

Definitely. But if you´re going with one side port+PP, you should IMO use secondary side port. Of course, if primaries can be ported to desired area and timing, then it doesn´t matter.

All good.

Well, problem is, that this setup will have very large port area and duration. It would be best to use PP as primary port and side port as rpm based secondary - I know, it sounds backwards, every combo port uses side port as primary etc. But no one has ever gave proof that its the right way to do it. Some argue that they´re minimizing overlap, but overlap is still there, acting as vacuum chamber pulling exhaust gases into intake at low load. On the other hand, there are few people who figured out how to make large overlap engines behave and this is it. Make PP with 80° BTDC opening and modest closing, like 50°-60° ABDC. This will create very strong torque curve from lowest rpms up to about 6000 rpms, then side port will come into play. Side port should be closed much later, like 80°ABDC. If you do it other way around, well, sideport won´t give you torque of PP, and in worst case, both ports running based on load will result in sluggish response and poor power at low-end and mid-range. Don´t get me wrong, I´m not bashing you, but given unusual setup you´re planning, you probably want something with advantages compared to usual setups and this is just how I see it based on mine research of rotary engines with combination intake systems and some common sense It won´t be so hard to use servo motor or other means to open ports based on rpms

I wish you all the best, hope you will keep us informed on progress

F1Pilot

I do like that idea Liborek. And once I have the pieces in my hands, it will be interesting to see if this is possible.

A motor mounted onto the primary port throttle shaft and rpm activated by the LINK G4, shouldn't be too difficult.

With the injector setup however, I may need to idle it off the primaries to have some flow through those ports to use the primary injectors which will be mounted in the stock position. Only reason I want to use those is for tip in response, which may or may not be an issue with the 1000cc secodary injectors in the standoff position.

So, I could have the primaries open a slight amount and have the throttle mechanically connected to the secondary PPs.

Unfortunately due to the throttle body design, it doesnt really let me use the secondary side ports. So hopefully if these are activated by RPM, the primary side ports will provide enough port area.

What type of motor would you use to activate the throttle shaft?

F1Pilot

Totally forgot about this thread!!

The car is alive!! Or has been, the throttle body is off for some changes.

I stuffed up a measurement and the tps doesn't fit, so moving it requires so giggling.

The staged throttle may or may not fit now.

Vids are up on you tube of the first startup, sorry about sound my friend doesn't know how to operate his phone!

F1Pilot