newbie trying to choose a 13B

[RX2Coupe]

Hi guys! need some advice on choosing a 13B for my project RX2. I have been reading a ton and i decided i would like to build a 13B because of the larger displacement and the aftermarket parts that are avalible. More bang for the buck. I didnt realize that they made so many 13b motors. I would like to build a NA street/strip motor. 13b, AP, 13B-RESI, 13B-DEI, 13B-REW, 13B TII, 4 port, 6 port??? I realize some of these are turbo motors and Fuel injected motors. Just not sure what would be the best foundation for a NA mill capable of someday making 200-250HP? Whats a good 13B for a Rotary newbie? As always any help is appreciated! Thanks!!!

[j9fd3s]

yes they did update the 13B over the years, but the good news is that most of the updated parts are things like the rotors and stationary gears, which fit any 13B, so it makes just about any 13B worth building.

if you want EFI it would be best to use an 86 and newer engine, they have injector holes already (and injectors and a fuel rail).

ideally you want the 4 port irons. the 6 ports dont respond to porting very well, so they are more power limited.

the 89-91 non turbo rotors are the lightest, and highest compression

the 89+ stationary gears are hardened from the factory, the 89+ tension bolts are nicer too

the FD bearings are better, you can pick a tighter clearance

the condition of the parts is actually the most important thing, the irons need to be flat, rotor housings need to be good preferably new, new seals, etc etc

[RX2Coupe]

Thanks or the info! Im leaning toward a 4 port for sure. I would love to play with a turbo motor but this is the first rotary I've ever played with so i wanna keep it kinda simple the first time. After i learn the ropes I will look into turbos. Anyone know were I can find a list of years,makes,models that came with 13b 4 ports? sounds like it might be the best place to start! lol Thanks for the reply! I was starting to think no body would

[TitaniumTT]

Efi 4 port engine are in turbo cars from 87 and up. Benefit is, if you build the engine and ecu, fuel injection and ignition system properly, after you're done playing in the n/a world, you can bolt on a turbo and have some real fun

[RX2Coupe]

I like the way you think TitaniumTT!!!!!!!

[Raksj04]

Are you planing on building one?

[My5ABaby]

Originally Posted by TitaniumTT

Efi 4 port engine are in turbo cars from 87 and up. Benefit is, if you build the engine and ecu, fuel injection and ignition system properly, after you're done playing in the n/a world, you can bolt on a turbo and have some real fun

Or just boost the 6 port...

[Raksj04]

Originally Posted by My5ABaby

Or just boost the 6 port...

Aaron cake did, Project Tina.

[TitaniumTT]

And its one of the biggest hack projects I've seen.

I can't weld aluminium, so I'm gonna build a mani out of steel and coat the inside....
let's use a megasquirt
I hate that project

[My5ABaby]

Originally Posted by Raksj04

Aaron cake did, Project Tina.

As am I, except I'm doing it the "normal" way. Using the TII intake on an N/A block and port matching the LIM. I went a step further and decided to use a standalone rather than stock TII parts (ECU, AFM, boost sensor) with a FCD.

[RX2Coupe]

Originally Posted by Raksj04

Are you planing on building one?

Yeah. Now that i got a idea of what to look for I would like to find one and go threw it. Im exited about it! A nice change of pace from piston mills!

[My5ABaby]

In general the best foundation is a 4 port (87-91 TII engine) that is N/A. However, it's so simple just to get a boosted rotary and make 200+ all day with basically 0 work.

[Raksj04]

I was told you can make good power with the N/A rotors in a 4 port engine with a turbo. I think the s4 NA rotors are 9.4 and the S5 is 9.7. and the S4 turbo is 8.7:1 and the S5 is 9.0:1. those where off the top of my head. The RX8 rotors are 10.0:1 but they need to be machined to work in a older engine. I know the apex seals are different and I believe the corner seals will cause you issues. It is just easier to run the 9.7:1 S5 N/A rotors.

here is the ratios and weights, I was off a bit.

Rotors: The S5 rotors have a higher compression ratio and lower weight than the s4 rotors.

S4 13b 6PI: 9.4:1 compression ratio ~10lbs
S5 13b 6PI: 9.7:1 compression ratio ~9.5lbs

S4 13b Turbo: 8.5:1 compression ratio ~10lbs
S5 13b Turbo: 9.0:1 compression ratio ~9.5lbs

[RICE RACING]

13B-REW and a 300bhp shot of Nitrous Oxide is what you need

[My5ABaby]

Originally Posted by Raksj04

I was told you can make good power with the N/A rotors in a 4 port engine with a turbo. I think the s4 NA rotors are 9.4 and the S5 is 9.7. and the S4 turbo is 8.7:1 and the S5 is 9.0:1. those where off the top of my head. The RX8 rotors are 10.0:1 but they need to be machined to work in a older engine. I know the apex seals are different and I believe the corner seals will cause you issues. It is just easier to run the 9.7:1 S5 N/A rotors.

here is the ratios and weights, I was off a bit.

You can make good power with the N/A rotors in a boosted engine (which is why I'm doing it), but the chances of detonation are higher due to the higher compression. I'm fixing this with e85 but a lot of people probably aren't willing to do that. I'm only doing it this way because I'm starting with a N/A platform. If I had my druthers it's just easier to start with a TII block.