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Naturally Aspirated Performance ForumDiscussion of naturally-aspirated rotary performance. No Power Adders, only pure rotary power!
From the "12A" to the "RENESIS" and beyond.
Primary bridge s5 13b
48mm itb
Microsquirt ecu
Direct fire ign 1a coils
All trailing plugs
Racing beat street port exhaust
255lph, 6an feed and return
2 id1000 injectors
55psi fuel pressure
Timing is 26* 5split
Saw No change except for hp/tq by decreasing timing down to 22* and more split. We believe the exhaust is becoming the choke point.
i'll never understand why people run two different port timings on half of the ports if they're not going to separate the two runners going to the different ports.
its the same as running an aggressive cam on one lobe and then a mild one and the other( 4 valves)
i could see if you ran two bridges but one was slightly sooner opening then the other, maybe as a swirl effect...
but you left the outside stock ? or "just" streetported?
Its a 6 port engine, saw no reason to add a bridge to the secondaries based on total opening. So they will always pull differently. Aggressive big street, with large exhaust ports. Added bridge to primary ports going into the housing (beveled). Runners are opened up and cleaned. This engine has reached 9000rpm before based on gearing and speed. Exhaust and external differences have acured since then but no internal work.
He's right about the port timing. If they're wildly different in opening and closing then they aren't going to play nice with each other when they share the same throttle plate. I'd hunt down some Turbo II end housings and port them to match the primaries. There is no real drivability difference between a half bridge and full bridge.
Depending on how long the dyno pull is, I'd also try colder plugs. If it feels like it is breaking up after 6-7 seconds at WOT, that is the plugs overheating. Heat range 9 is still kinda hot at this power level/RPM. My car would pull great in the lower gears on the street but on long straights on the rallycross course it would break up and lose power. Problem gone after switching to range 10 plugs. Also picked up some top end acceleration at the dragstrip, for the same reason. It no longer felt "flat" sitting at the top of 3rd gear.
Had a adaptronic 440 laying around from an abandoned project. Wired in, with plx and interface board. Pulled clean to 8500 limiter. So I'm guessing the microsquirt was damaged.
Try running some gappable plugs with tigheter gaps. The dyno looks like you're getting spark issues up high. I run NGK BR10EG in my turbo car. They're super cheap and gapable like a conventional plug. Plus they're a colder heat code. I daily drove on the same plugs for 4 months without issues.
03-13-16, 09:05 AM
