Impact of engine temp on mapping

[Dave McCulloch]

My 1900K seems to be running in happily - now covered 560 miles - with a rolling road session booked at emerald on 9 December. When I built the new engine I fitted a 74 degree stat and lower temp fan switch (can't remember the logic now, but it seemed sound at the time....).

 

However, in this colder weather the temp gauge settled at 60 unless I was stationery - it then rises to 70ish and sits there for quite a while (presumably as the stat is now drawing in water from the rad) until it then starts to rise again and the fan then cuts in (with the temp cycling between mid 70s and mid 80s). The problem with this is that i) the oil temp only ever got to 60 and ii) there was sod all hot air coming out of the heater (the old engine has the standard 88 (?) stat and the heater would toast my lower half nicely ).

 

I'm now thinking about reverting to an 88 (or possible 82) stat, but am not sure I'm going to have time to do this before I get the engine mapped. Will changing this affect the mapping? And what is the advantage of the lower temp stat (seeing as I can't remember now and previous threads appear somewhat inconclusive?).

 

Thanks

 

Dave

[oilyhands]

If the engine never gets to operating temperature it will have an effect for sure, the corrections to the map for 60 and 70 degrees are 10 and 5 percent respectively so I would make sure that you have an 82 'stat in ASAP.

 

Oily

[Myles]

I run a 74 deg C stat - as far as I'm concerned, it allows the engine to remain within a much narrower temp band than with a higher-rated item.

 

Cold-weather running aside, the SPA gauge shows the coolant to stay around the 74-78ish degree mark under normal running - and flipping the fan on when entering traffic keeps it there. I see at most a 10 degree cycle.

 

According to the Minister Power site, the target temp should be 75+/-5 deg C for most of the k-series engines in the Caterham application, so I'm quite happy where I am...

 

The stat and fan-switch should be matched - no point having a 74 degC stat if it takes the fan-switch until 92 degC (standard) to kick in - the temp-cycle is horrendous! Similarly, if you've got a 'lowered' fan switch and then put a stat in that is only a few degrees cooler - then the fan will be kicking in and out needlessly.

 

Dunno about the effect on mapping - the general advice of mapping with whatever spec you intend to run longterm probably applies... ...and it'll probably get reasonably-warm when Dave shuts the doors for the mapping session anyway - so that 50degC oil-temp will probably be a tad healthier...

 

 

In normal weather, with a coolant temp of 74, my OT is usually a couple of degrees higher in road-use. Given that the Apollo tank flatters the OT by as much as 10 degrees due to the cooling-effect of the tank, I'd say my OT was fairly healthy too. All bets are off in cold-weather though...

 

 

Project Scope-Creep is live...

 

Alcester Racing 7's Equipe - 🙆🏻™

 

Alcester-Racing-Sevens.com

---

 

Edited by - Myles on 27 Nov 2005 19:39:08

[Shaun_E]

I put an 82 degree stat in my 1900K and use the Emerald to control the fan switch. So far, in the recent cold weather, the water temp is in the low 70's while moving and oil is about 60.

 

Yellow SL #32