mfi question for swap from ssi exchangers to headers

[advtracing]

Swapping my 2.4ltr system from ssi heat exchangers with twin out gutted dansk mufler over to headers and custom gutted two in two out rsr style muffer , so question is will this lead to the engine running leaner and require enriching or should is cause no change

[HughH]

John

i don't know for sure but suspect it will make a small change

When i changed from a stock muffler (with a couple of air leaks) to a new Dansk Sport one it did make a minor difference - but that was also in the context of trying to fine tune the MFI anyway

[TEC69E]

Hi John. So you're going to have to figure out the warm-up thermostat setting cause the pre-heat pipe will be gone. What worked for me was to set it to the normal operating temp setting which is near fully depressed. Then I'd suggest using an AFR meter to get the main rack and then idle adjustment correct. I'd do the main rack first and then the idle last. Really no way to tell what adjustments will be required without an exhaust gas reading with an AFR meter. Lots of great info on this is available on the PP forum. Search for 'MFI Open Heart Surgery'. Don't think you'll need to worry about the black/white screws in the governor, but they can also be used to dial-in the midrange and high end if required. Lots of satisfaction from learning how to do this yourself. Good luck.

[RSTarga]

I'd be surprised if you saw any noticeable power gains over your original setup. The SSI's are really good.
No heat and MFI complication's don't help IMHO.

[geneulm]

Ssi s are capable of flowing to well over 230hp. If the ssi s were good enough for this level, larger headers won't do anything except cost you torque. If headers don't uncork or free up any additional potential, no additional fuel should be required?

[advtracing]

the car is a rsr rep and i don't run heat now , so clean up/ remove all heater items leaving only the windscreen blower plus adding the headers to clear the rear area . not after power gains just tidy up and correct the look.

[304065]

yes, i would expect you will need to richen up a bit.

not having the heated thermostat will introduce a source of randomness-- the thermostat is heated with 175F air and following a warmup period that matches the engines the pump will lean out. The hot oil from the engine will heat the pump up itself, but this takes a long time. Better that you disconnect the thermostat entirely or use a cable-operated cold start mechanism to richen the rack to start, then take thermostat input out entirely.

I agree also that an LM-2, with a pair of widebands (one on each bank) will go a long way toward telling you what is happening.

[Mr9146]

Set the rack to the "warm" position and adjust as per usual.

Car will be a bit finicky when cold but that's what hand throttles are for. Usually sorts itself out in a few miles.