I'm looking at purchasing my first rotary and been reading... it's a whole lot different than pushrod engines.

Looking at a 13b from a 1990 Rx7 that has peripheral porting, racing beat upper manifold, side draft throttle body with fuel injection, and I think a tec3 management system. He said it made around 150whp but from what I'm reading online, if a 13b has PP it should be a) very hard to street (which doesn't matter too much cause it's not a daily driver) b) should be making a LOT more power.. like 300hp NA?

What influences how much horsepower you're making once the housing is ported? It's not like a LS1 where you throw the cam in and it changes the engine's strokes. Is it possible the engine was de-tuned to be more street-able or just possibly the stock fueling was the limitation?

For fueling I believe theyre just stock 1990 fuel pump and injectors.

I'm not overly concerned about the power, I just want to know what I'm getting myself into. Is there room for growth for horsepower if it is truly PP? And if so, what would I need to upgrade in addition to what's done (PP, standalone ECU) in order to get more power out of NA?

Thanks

EDIT: the engine is a fresh rebuild from what I'm told and I have no reason to doubt based on the quality of the work on other things on the car

 

Edit: thanks to the mobile app suggesting this thread, I didn't realize it was almost 2 years old. :/

Hi @pan .

I currently have a 13b peripheral port in my FC and can definitely shed some light on this topic.

First things first:

• If the car is actually peripheral ported, was correctly built, has good compression and is tuned correctly, you can make near 300whp NA. My last dyno was at 280whp on a crappy old haltech e6x ecu (poor controlling and tuning features).
• That said, there is no way that engine will run on a factory fuel pump or injectors. The only possible way is if the car was only tuned to ~4k RPM (which would explain the 150 hp you've mentioned). I'm currently running x2 ID1700x injectors and a walbro 255lph fuel pump. It is very likely the stock fueling is limiting any additional power to be gained.
• Peripheral port engines are not very streetable. Don't get me wrong, I drive mine as often as possible, but they can be a bear in traffic and low rpm. They really want to be up higher in the RPM range.
• I'm not familiar with the ECU currently installed but from a quick glance, it seems to be a fairly uncommon one for use in rotaries. Based on the information I could find, it looks like it will still work for your purposes if you find a competent tuner who is familiar with the Tec3 software

Bottom line:

• You will need a much larger fuel pump. A Walbro 255lph will do the trick, is relatively cheap, and basically drop in for the FC chassis.
  • Make sure you buy genuine and not a knock-off, as there are many fakes out there.
• You will need larger injectors. Ideally, a total of 3400cc's of flow (this will leave you a bit of headroom, so you don't max out the injectors).
  • If your engine has a primary and secondary fuel rail (4 injectors), you can split this by using x2 smaller primaries and x2 larger secondary's.
  • Or you can do what I did and run one fuel rail with two ID1700x injectors.
• Exhaust plays a huge part in making power on a peripheral port. You can choose either a long or short primary system (this is where the two pipes from the header merge).
  • Most rotary racing specialists (Racing Beat, Pineapple Racing, Atkins, etc.) generally agree on the pipe size, length, and collector types required for both systems.
  • Long systems generally produce a broader power band with more low end torque and short systems generally produce higher peak HP with a smaller powerband.
  • This information can be found in Racing Beats rotary performance catalog PDF (found on google)
• Compression test the engine before you do anything. Doesn't matter if it was just rebuilt. Compression test it anyway, so you're not wasting money. You can even use a piston compression tester by taking out the schraeder valve and checking the pulses as the engine is cranked (if you need more information on how to correctly do this, feel free to search or ask)
  • Make sure the engine is healthy, your oil cooler is working, you have sufficient oil pressure at high RPM, and that you have an upgraded radiator (with a clutch fan or an e-fan with at least 3600 cfm).

Assuming you have most of the bits to get this engine going strong, it will be a blast once complete

 

unfortunately the OP last login was feb of 2020.

 

Caught that after posting. Can't delete

 

djSL - Very nice and thorough break-down and analasis. But as said, the OP (original poster) was only here briefly and prolly won't see your great reply.

But it is good to have your experience and knowledge on FI and engine management. I am a carb guy but when I decide to switch to EFI throttle body Ill look you up.

 

BUT good sir, I HAVE SEEN THIS GREAT REPLY!!! Thank you. just blew a coolant seal and I think its time for a rebuild, I was looking at PP housings but I want to street and drift it, and so I was thinking semi pp. ty for all the info