Speedworks

Hy,



I'm rebuilding my engine (new housings and new irons) and my irons are ported with the Judge Ito aggressive streetport templates.





Normally th plan was to do the housings wit a Racning Beat mild steetport exhaust porting but I'm a bit reluctant to that as Racing beat told me that exhaust porting will affect emissions far more. And as my country is quite harsh on that I'm considering to keep the stock ports.



I will be running non seq turbo's on stock boost and little more (later maybe a GT35R single kit) for a long time and the power goal is 350-400ish HP in the long term.



The RB mild echaust port isn't tha much bigger than the stock port (it just cloeses a tad later) so I don't really know how much effect that will have.



Any info will be highly appreciated.



Neal

Speedworks

Anyone?

Jeff20B

It sounds like you have a 2nd gen engine. Those already have decent exhaust port timing. You can cut it up to the edge of the sleeve, which is a pretty small increase compared to the port to sleeve ratio (portability) of earlier housings. Those started out with much smaller port timing but the sleeves are roughly the same size.

Speedworks

Hy Jeff, My engine is 13B REW (FD).



These have already bigger exhaust sleeves than the 2nd gen engines.



The issue for me is that the raceport templates are out of the question for my use on this engine, and the mild streetport is next to nothing compared to the OEm ports on my (new) housings. So I prefer the leave them 'undamaged'. maybe losing a bit power, but what the hell.

diabolical1

i don't get how the Ito intakes are going to make emissions any easier with stock exhaust than ported exhaust, but i don't claim to have even half the knowledge of the RB collective, so i guess there is merit to their advice. if it were mine, i would port the exhaust, but given your thoughts and concerns i'd say you'll meet your power goals just fine even leaving them stock. good luck with it.



just curious ... in what country do you live?

Speedworks

Hy I'm in Belgium. Honestly, today I spoke a rotary friend and he tols me thesame about larger exh ports not affecting emissions.



The only reason i'm considering the exh streetport is to minimize turbo lag on the non seq twins.

j9fd3s

porting UP on the exhaust increases overlap, the time the intake and exhaust ports are both open, which is good for power, but bad for emissions, as the unburned intake mixture, can go right out the exhaust.



porting DOWN on the exhaust, shortens the power stroke, it should (in theory) also result in higher emissions because all of the mixture in that chamber might not have finished burning yet.



good news is that the fd ports are already pretty good (its like an fc with a better match to the sleeve), so it doesnt need as much work as some of the other engines do.





what kind of emissions testing do you have? is it a stationary test? or a dyno. our california test is done on a dyno at 15mph and 25 mph, and this test is much easier for the rotary than the old idle and 2500rpm unloaded stationary test.



ive tested tons of rx's with both kinds of tests and the KEYS to passing smog are that the air pump is pumping air into the exhaust ports during the tests, and that theres a working converter in the exhuast. on an fd this means its essential that the F and R rotor housings are not swapped, doing this blocks off the passage and is instant failure.



i have smogged a 6 port car, with the intake ports all open, it seems like the extra intake duration doesnt have a big impact. and earlier intake opening will though, its the same as porting the exhaust up.



in ca usually we've got to be better than 115hc's and .05 co, although the exact numbers arent published

Speedworks

We have stationary test at 3000rpm.



But I have decided to go with the stock ports in the end... as the FD ports already flow better htan the FC.



Thanks for the info and support!!

j9fd3s

oh thats not a problem, my friends gsl-se passed the 3000rpms test with no cat at all