Good to know, thank you! I was thinking the ECU sensor is in the ideal spot.

My upgraded rad and cooling system should be functionally identical other than the pump and in theory the S2 pump should be a lot better.

 

Just realized I likely don't have the restrictor in the upper hose from t-stat housing to coolant bottle. I ordered an OEM hose with that, and will probably throw the bigger restrictor into the heater core hose as the typical "MIAC" fix though I don't notice the noise.

 

Did you ever consider the possibility that the S2 water pump impeller might lose it’s effectiveness when under-driven?

 

I have, yes. Temps do seem a little better with it under driven. I've only done one event when under driven though. Idle and cruising around temps seem to be completely unaffected (meaning it's not so slow that it's struggling to cool)

 

i only ask because the only reason to under-drive it on the S1 is to avoid cavitation with the rudimentary design of it’s impeller. Even Mazmart recommends not under-driving their improved pump-style impeller design. Was thinking it might be worth testing to see if cooling improves by overdriving the S2 pump like a pump impeller would, but then it won’t really matter to increase flow if the radiator can’t cool it quick enough as a result.

 

The thread with CFD of the two S1 pumps (stock and Mazmart) is an interesting read. Would love to see that done with the S2 pump as well. The Mazmart pump was interesting in how much lower flow it had (while also not cavitating) but everyone that runs them on track cars sees *way* better cooling. I'll keep trying things for now. Definitely going to put the properly restricted upper AST line on instead of the poorly fitting silicone line that I have and go from there.

I have parts on order to build a Mazdaspeed style intake like Brett made, hoping to get air out of the radiator quicker that way too.

Also, another factor is that the S2 has the aluminum panel under the oil pan sealing even more air into the engine bay... I've not seen anybody else tracking/autocrossing an S2 that's tracking coolant temps so maybe I'm "fine" and it's not going to get better without hood vents or something to get hot air out of the bay.

 

I don't know why you guys are having problems. I did a test day on Sunday and even after five or six back to back runs with no cooldown my logs don't show water temps ever getting above 190F. :P

 

there are a couple of simple, small changes to the OE system that help to relieve that, but the STX ruleset doesn’t permit them

 

Like tossing the A/C? or God forbid a piston engine swap?

 

well those obviously aren’t allowed in STX, just as John was obviously kidding, but my comment is relative to the OE Renesis cooling system configuration.

 

did the heater hose location read higher or lower than the ECT sensor?

 

Lower, something like 10 degrees.

 

Curious what the changes are, even if not relevant to STX.

Temps were "fine" yesterday on a lower speed course. Max speed ~56 mph and ~30 second runs, peak temp of ~205F on course and climbed to 210F on the crawl back to grid.

 

I think Team is referring to the body work mods for cooling. I'm not 100% sure on that, maybe he'll clarify. But from my understanding, it means you can't make hood vents that serve the purpose of cooling the engine bay, as then it's a functional vent that's not from the OEM. But I could be wrong about the intended definition of "functional" and "non-functional".

F. Addition of spoilers, splitters, rear wings, bumper covers, valances, side skirts, and non-functional scoops/vents is allowed provided that either:
1. It is a production part which is standard or optional equipment of a US model of the vehicle. (“Model” is defined in Section 12.)
2021 SCCA® National Solo® Rules — 87
Section 14
2. It is listed in the vehicle manufacturer’s US accessory catalog for that vehicle for normal highway use. This does not allow for parts sold through a manufacturer’s performance catalog (e.g., Ford Racing, HPD, Mazdaspeed, Mopar Performance, Mugen, NISMO, SPT, TRD, etc).
Parts must be installed as directed by the manufacturer. Exact replicas, including weight, from alternate sources are also permitted.

 

nope, mods to the cooling system, not the bodywork.
.

 

I'm not sure what you're referring to then, because from what I could tell, most cooling mods are allowed provided they're not reducing weight/capacity.

 

Went and got my car dyno'd... I've had weak/sluggish starts for a couple of weeks. Looks like one or more of my coils died. BHR D585, so I upgraded to the new BHR OEM direct fit coils and all good now. Just a waste of a dyno session, haha.

 

those D585 coils never fail, everyone on the forum says so …
.

 

Yep... just waiting for the "compliant" coils to have issues because they're still D585s inside, but at least I'll be able to have Charles replace them. My car came with the LS style D585s from BHR so I can't have them replaced under warranty.

The most interesting part is that my AFRs under load were off everywhere with the weak/failed coil(s). My expected AFR is 13:1 AFR and as you can see it was well below that especially after APV opened.

 

I'd throw those away and just get the IGN-1As.

 

waits for the new dyno to be posted …

 

Gonna be a while, no chance to get back for a while. Hopefully before nats.

Data logs are back to normal mid 220s g/s now, so meh.

 

Have been testing Nankang CR-1 as the Yokohamas aren't readily available and we're saving them for nats. Did some more testing this past weekend, this time at Pocono! Amy's first real experience using third gear on course and we sorted out the feel of the Nankangs! They feel a lot better and they seemed to be more on pace too versus where they were at for NNJR.

Amy's fastest run:


My fastest run:

 

Under what circumstances does the pump cavitate? Sincerely asking.

 

continuous high rpm

It’s main purpose is for street car use, not a competition vehicle operating at high rpm for extended periods of time.

which most owners tend to over-rev their Renesis engine unnecessarily as well.
.