clubber

I've looked around for a while and AFAIK, noone has ever listed all the normal (street) engine upgrades that can be done. I've got a good early 13B to rebuild and I'd like to get some cool mods if possible. Some of the stuff RUMORED to be true that I've found so far;

Lighter rotors are better but you can't run 2nd gen or later rotors in earlier engines due to geometry changes. This seems false otherwise Mazdatrix coundn't sell a light rotor engine for first gens and they do sell one.

Renesis cranks are lighter and stronger than older stuff and recomended in a performance build.

ARP stud kits are a good idea for more revs and they negate the need for dowel pins. The oversized studs are rumored to cause problems if done wrong but I don't know what problems.

Racing Beat has aluminium end housings but at a major price penalty.

Bigger oil pumps are always the better choice

2nd gen water pumps can be installed for a weight savings.

Street porting isn't always a good idea if you like the low end torque of a stock motor.

There is lots of info on apex seals and many that have conflicting viewpoints and I have no experience with anything other than stock. You can search for this and get tons confused by the wealth of info.

Rotor housings cannot be repaired when bad but I'm not sure on this.

Any other stuff???

I'm just trying to get a good street and autocross NA motor so any info is appreciated. I figure others will be interested too.

Rotospeed

iTrader: (8)

is it a 4 port or 6?

1. yes, you can use a fc rotating assembly in an old school 13b

2. i dont know

3. true ish, but others can give you the details

4. maby but i dont see the point for your applacation

5. yes, all s3 engines had the bigger oil bumps and i dont know about fcs

6. yes fc housing and fb (GLB brand i think) water pumps are both aluminum

7. true ish, are you talking 4 port or 6? if its going to be an autocross car check your rules before you do any porting as it may bump you up a class

8. you cant go wrong with stock, im using Goopy seals and love them. others can give you more info ....

9. depends on whats bad, chrome flaking cannot be fixed but if its a small amount they may be useable but not ideal.

other more knowledge able people will chime in and can give you more detail

clubber

It's a 4 port and on that subject, a few around here believe that they are better than 6 ports. Perhaps soon I'll know the answer to that. As far as checking rules for porting, it's going in my Maxton which is classed in E mod by the scca even bone stock so I can do a lot with no further class penalties.

j9fd3s

iTrader: (3)

1. you can run the later rotors in an early engine. there is a geometry change, but its so slight it doesn't matter too much, its actually not even visible if you have both housings together

2. Rx8 are lighter. its not needed, but if you need to buy one, its a good option

3. i've done a couple of stock diameter studded engines, and my OPINION is that there isn't a big problem with engine twist until you're really making big power (400+ on a 2 rotor), and B the stock diameter studs don't help with a twisting problem! the larger ones should, but the factories solution was to use the dry sump plate and a plate on top, and little skinny tension bolts. i would say on a non turbo "street" engine the ribbed S5 and later tension bolts are all you need.

4. the RB housings are over $1000 each, so they are probably out of budget, unless weight is that big of a priority. the low buck weight savings would be to run an FD engine, the irons went on a diet in the 80's so the later ones are much lighter.

5. yes. you want the 17.5mm oil pump if you don't already. its not a bad idea to bump the oil pressure either, the FD regulator is $30 new.

6. yes, the 86-88 water pump assembly is very similar to the 74-85 cast iron unit, except its alumium, so since they are really cheap used, and the weight is high and up front its kind of a nice mod.

7. low end torque comes from chamber sealing. the rotary has a lot of seals, and its got longer strokes, so there is more time and more places for leakage. if you build a really tight engine, even with a street port the low end will be better than a tired stock port.

8. there IS a lot of conflicting info about apex seals. seal choice depends on the application too. for instance if its a high (over 8500rpm) engine, the carbon seals are a better choice. for normal rpm engines the stock seals are going to seal best, however they are probably harder and thus more brittle.

9. goopy, and a couple of other places can fix really minor things, but they are wear items so they aren't really supposed to last forever.

my advise would actually be to skip the fancy parts, and just build a really good stock engine, with a couple of the updates, like the FD oil pressure redulator. if its a 13B the FD or Rx8 stationary gears are hardened, and come with the racing style bearings. actually the FD stock specs are better than the race car stuff from the 80's....