Going to be building up my first 13b here shortly. The more I read and learn, the more I understand that doing a BP will require 8500+ rpm. This of course seems to require the hardened gears, rotor clearancing, and engine balancing. Adding considerably to the cost (I've only checked 2 sites (RB and MT), but I'm assuming everyone is close on the machine work). I'll be buying 12A side housings to port out as advised by atkins (more meat, not as hard to FU). I have a 6 port motor now (91) to use as a core. If need be, I'll buy new rotor housings.

Motor is to be in a 1600lbs car, mainly driven on the street to have FUN with, definalty NOT a daily driver (I have a few). Carbs and distributor will handle the engine's fueling and spark.

My main question is, can I make 200hp or thereabouts, without spinning the motor to 9000, and subsequently requiring all the high RPM parts?

Big SP is what I'm leaning towards.... but there are so many damn options... make a 4 port from the 6? half BP?

 

it depends on the porting.

The milder the porting, the less torque you make, so the higher you must rev.

A decent P-port will make 200hp at about 6000rpm...

Re-think using carbs... carbs are great but EFI is even better.

The peripheral port engine I'm currently constructing is designed to have a thick meaty powerband in the midrange, where it's really useful. It will use carbs to start with, but EFI will definitely be in the cards for later. The carb will limit the type of intake manifold I can use... there's just not enough underhood space to fit the runner length I want, *and* the plenum size I want, *and* the carb *and* the air filter. But with no carb, just a throttle body, the options are greatly opened up.

 

double post

 

just a word of caution before you make a mistake, realize that the 12A side housings are not compatible with '91 13B rotor housings (no where for the water seals) ... the NEW rotor housings that you buy will have to be for the '84-'85 13B-6PI. for a Gen II 4-port, you'd have to use T2 side housings.

 

exactly why I posted my intentions.. There seems to be a lot of mix/matching available, but it would be easy for someone like myself to get it wrong

SO... I'm still a bit confused about what you said. To use the 12A housings, I'd need to buy or find 84-85 6 port ROTOR housings??? AND If I wanted to use the rotor housings from the 6 port motor, I'd need T2 (4 port) side housings. Is this correct?

Can I make 200hp with a 6 port? I don't think a PP is in the cards for me. Housings costing 1000$ each, and the high rpm's will add to much to the cost. At that point, it would be much more economical to just do a blow through turbo setup.

I like the NA for the simplicity in the setup. I like the carbs/distrib because I want something different. I've always had haltech or other efi managment, and I want to do a "retro" type thing. I think 200hp in a 1600lbs car would move it decently down the road/track. Since it's a FUN project, and really won't be competitive in ANY form of auto racing (stuck in wrong class always), the idea is to spend only what I need to spend. If I can make 200 with a 6 port motor, then why do a PP motor that will cost 3X as much?

Please forgive me if I have the wrong assumptions about cost and power. I'm a NOOB when it comes to spinning triangles.

 

at the flywheel? Yes ... a good streetport and carbie will do it fairly easy, someone here even got 215 with the stock SE injection in place.

at the drive wheels? Yes, but you'll probably end up with something not too street-friendly (my opinion)

 

There are two common engine types where you can interchange housings: '74-85 and '86-02. (Not counting the RX-8 engine) '74-85 has the coolant O-rings in the rotor housings, '86-02 has the coolant O-rings in the side housings.

The '74-78 13Bs used the exact same side housings as the 12As of similar vintage. GSL-SE rotor housings however are the ONLY ones that are available new, with the coolant O-rings in the rotor housings, if you want to use 12A side housings. Putting GSL-SE rotor housings with 12A side housings just makes you a '74-78 13B, except with oil squirter passages.

 

sounds like my goals can be met then. All I need to do now is figure out which carbs/manifold, source the housings, and put this thing together.

If I did decide to go with a BP, is 250hp a possibility? If I can find the components nessicary to build the motor without breaking my budget, I could then spring for the high RPM components nessicary to make the motor live up there near 9K.

 

If you build the port to make power up there, it'd be hard *not* to make 250hp.

 

what else do I need for high RPM operation?

Hardened gears, 3 window bearings, oil pump mods? I can't afford the 2000$ RB lightweight rotors, but I'm not sure how many out there actually spring for those?

I understand that the clearances will need to be spot on, and that the rotors will need to be clearanced on the side to run at that high of an RPM.

51IDA on the carbs?

If I did go with a bridgeport, would a smaller bridge be more "reliable"? So as not to get close to the water seals? What about that post I saw/read about, someone using a side seal to add a bridge to the water seal, sort of like a fence?

What kind of power band do the BP motors have? I'll I've really been able to find are dynos for boosted motors and FI. Power not unlike a NA honda engine I'm assuming? (little to no torque ~100ft lbs) with all the power coming on up high right?

 

Descion has been reached.

13B BP motor.

I had sourced TII housings, but I'm looking for Series 5 rotors (NA) and series 5 stationary gears. Best thing would be to find a S5 TII motor core. Know of any available?

 

hell, a well tuned standalone (or even an safc) intake, exhaust and a few other bolt on goodies will get you to about 200 crank hp on a STOCK BLOCK s5 n/a. youle probobly hitmax hp a little after 7k and have power out until a little after 8k.

some porting f the s5 irons (maybe a 1/2 bridge) and you could have well over 200 and still not realy need to upgrade the internals. just keep it under 9000 and youle be fine.

200 hp isnt asking that mutch of an n/a.

 

carbon apex seals ...

 

Found a good deal on a S5 TII motor If everything is ok in the motor (going to look on fri), I'll have the motor, swapping the TII rotors for NA s5 rotors.

Off for BP'ing. I'm now looking for S6 gears, my S5 gears will be for sale soon I believe.

 

...and bye bye engine longevity and low-rpm torque.

I'd gladly trade off over-8500rpm power for iron seals.

One nice thing about the carbon-aluminum seals... they're very housing-friendly, and they're still only $30 a pop while the iron seals are almost double that.
When you figure in the housing friendliness, it just might be more cost-effective to run the carbons and just rebuild more frequently.

 

I didn't realive I could use the S5 or S6 gears. THought I had to spend 600 on gears from racingbeat....so it's going all out BP. Oh yea, and some trick carbon seals from CLR

 

WOOT! I picked up a S5 TII motor, S5 NA rotors, TII Trans, and will be headed back to grab the S6 gears. Just bought a set of Weber 51idas as well :-D

 

A SET????

 

well, I suppose they are joined, so I should have said "I just bought some weber 51ida's".

In any case, I have only enough for one motor :-D