Project STi ... the next steps

[danr55]

The std subaru thermostat opens at around 85C iirc to allow the water to flow to the radiator and get cooled.

The Zero Sports Thermostat opens at 77C i believe. This allows the water to run cooler. (available from Lateral Performance amongst others)

Cooler is better to a point.

An added benefit is that the water cools the oil in a modine near the oil filter transferring heat from the oil to the water. As the water is colder it cools the oil more.

Much cheaper than £300 for an oil cooler.

Got a low temp thremostat which was got from RCM, pretty sure they said it opened at 72C !

was it the Zero Sports one? how much did it cost? How easy are they to fit?

[WR 1mposter]

The std subaru thermostat opens at around 85C iirc to allow the water to flow to the radiator and get cooled.

The Zero Sports Thermostat opens at 77C i believe. This allows the water to run cooler. (available from Lateral Performance amongst others)

Cooler is better to a point.

An added benefit is that the water cools the oil in a modine near the oil filter transferring heat from the oil to the water. As the water is colder it cools the oil more.

Much cheaper than £300 for an oil cooler.

Got a low temp thremostat which was got from RCM, pretty sure they said it opened at 72C !

was it the Zero Sports one? how much did it cost? How easy are they to fit?

No idea which it was Dan, dsa just ordered it from rcm and they fitted it !
Been waiting for it to be fitted since the last rr at wrc, which they said it was sticking until 90+C probably the cause of slightly lower figures

[dynamix]

I fitted mine - so it isnt hard

Fitting:

1) remove undertray (4 bolts, 4 clips and 2 slidey clips)
2) place washing up bowl or water catcher under the engine
3) 10 mm socket and remove the 2 bolts holding the thermostat cover on
4) remove thermostat
5) place new thermostat into the engine block (it can only go in one way and needs to be rotated until seated corrected - you will know when this is)
6) re-affix thermostat housing with 10mm bolts (dont overtighten)
7) fix up with fresh coolant
start car up and run til hot to check for leaks

Less than an hour to do it - or 15 mins if you are good

[marky mark]

I would be interested to hear Marky Marks thoughts?

They can't do any harm, and i don't have any experience of them personally. It's always better to listen to someone who a) has a clue b) has some experience c) does not sell what he is on about.

Dynamix meets all the criteria i think.

Despite my asking, i have yet to have anyone explain how this actually lowers your water temp though. The rating is purely an opening temperature. So the only difference is that the car will take longer to get to full temperature. The only way it can make a difference to overall water temp is if when it is open it is less of a restriction or it opens further. Ideally you would have no thermostat (we remove them on bikes) so you have no restriction and full flow to the rad even on a cold start. Problem is on a road car on a cold day you might never achieve operating temp.

If Dynamix is noticing lower oil temps after fitting one, I am certain this is nothing to do with the modine and far more likely due to conduction through the crankcase and head as these will obviously running cooler (if the new stat opens further or let more water through as I state above).

We completely remove the modine on some bikes and it makes no difference to oil temp whatsoever. If you think about it you are trying to cool oil with a media that is actually hotter than the oil. They are a little bit of a gimmick.

I would love someone to explain to me how a thermostat that opens at 77 deg and one that opens at 85 degrees has a bearing on water temp that is running at 100 degrees + though. They are both open, how does it lower the temperature?

[WR1 Bro]

That was exactly my concern. I can see how it will take the oil longer to warm up but I couldn't see how it would alter the temperature on a track session.

More facts required. Very interesting thread again Dynamix.

[dynamix]

Thanks Mark... I think

ok - laymans terms of how it works.

When you start the engine and it is cold the thermostat is closed. At this point all the water is circulating around the engine waterways. It does not circulate into the radiator. This is so that the water gets up to temperature quickly. It needs a certain amount of heat to make the engine run smoother.

Once it hits the temperature rating of the thermostat, the wax in the thermostat expands and opens the thermostat gradually until fully open. When this happens, the water then flow around the system including the radiator. It gets cooled by the air going through the rad and/or by the fan. It then goes back to the engine slightly cooler.

If the water cools to a sufficient degree the thermostat closes again gradually until the water hits the threshold again and the cycle continues.

Because this process happens at a lower temperature on the cooler therms, it rarely gets to the stage where the fans come on for added assistance in cooling (around 96/97C) or even above 85C on track with sustained hard use. (it still gets hot when stationery though)

The result in my case is that the fans are hardly ever on whilst on track now (Previously there were logged to be on quite a bit using delta dash) and average water temperatures are substantially less overall. Because the ECU has inbuilt compensation for high coolant temperatures it retards the ignition if the coolant is too hot, so this has an added performance gain on track and also as it runs cooler it will take slightly more timing (i havent tried this last bit myself as it is beyond my level of daring at the mo)

The water circulates through the modine that exchanges heat with the oil. This modine has two purposes - 1 to help get the oil up to temp quickly if the water is higher in temp than the oil and 2 to cool the oil down if the oil temp is higher than the water.

If the water is on average 7-8C cooler with the new thermostat - this is directly reflected in my experience in the oil temperature with my oil temp gauge and from logging the ECU for water temps.

I ran with a drilled out thermostat after the september ring trip so water was flowing through the rad all the time and water temps on a cruise would not go above 60-65C and took an absolute age to warm the car up - not ideal so I fitted this stat.

[dynamix]

That was exactly my concern. I can see how it will take the oil longer to warm up but I couldn't see how it would alter the temperature on a track session.

Oil and water take no longer to warm up as there is no difference with the std stat until the cooler stat opens. Therefore the engine will get up to 78C in exactly the same time as before. It just doesnt go so far above that.

[danr55]

its all so confusing my my tiny little brain!

[WR1 Bro]

I'm with you Dan... we truly are the WR1oc knuckle heads!

[dynamix]

ok - let me put it in even simpler language

Imagine if you will two baths ...

Bath 1 has the overflow at the top
Bath 2 has the overflow 1 inch further down

Both baths have taps running pouring water into the baths at the same rate

Which one gets half full quickest?

[danr55]

ok - let me put it in even simpler language

Imagine if you will two baths ...

Bath 1 has the overflow at the top
Bath 2 has the overflow 1 inch further down

Both baths have taps running pouring water into the baths at the same rate

Which one gets half full quickest?

OK, I'm with you, I think. I'm tempted to give one of these a go, will see how i get on at Cadwell this time around first. Not sure if the recent mods will make any difference either way on oil temps

[WR 1mposter]

Dynamix excellent explanation !

Even shite for brain such as me understands they will warm up the same, but when 77C is reached the 85C will warm further !

Bro Dan......dripppppppppp

[marky mark]

Nice explanation

Totally understand where you are coming from with that Dynamix. I never had a water temp gauge though and i was under the assumption the water ran at around 90-100 degrees normally. If this was the case then i still cant see how a 77deg thermostat makes things run cooler than an 85.

If a normal running temp was in the 85 region then obviously it does though.

What i am sure of is though that your lower oil heat is because of heat transfer to the water jacket through the liners/crankcase/heads, and not through the modine.

[dynamix]

cool - either way it was an added and unepected benefit

[dynamix]

I went out and did some testing

2nd gear:
30 - 50 mph = 1.3 seconds

3rd gear:
30 - 50 mph = 2.1 seconds
40 - 60 mph = 1.9 seconds
50 - 70 mph = 2.0 seconds
60 - 80 mph = 2.5 seconds

4th gear:
40 - 60 mph = 2.8 seconds
50 - 70 mph = 2.6 seconds
60 - 80 mph = 2.6 seconds
70 - 90 mph = 2.8 seconds
80 - 100 mph = 3.3 seconds

Still got some tweaking to do on the map namely at high revs but heading the right direction

[WR1 Bro]

4th gear:
40 - 60 mph = 2.8 seconds
50 - 70 mph = 2.6 seconds
60 - 80 mph = 2.6 seconds
70 - 90 mph = 2.8 seconds
80 - 100 mph = 3.3 seconds

Hi Donk, these are my 4th gear Delta Dash figures supplied by Bob Rawle. I thought you might be interested as a comparison.

40 - 60mph = 3.5 seconds
50 - 70mph = 2.9 seconds
60 - 80mph = 2.8 seconds
70 - 90mph = 2.9 seconds

I will make sure I get some updated ones when the turbo is changed sometime next week.

[dynamix]

cool Bro - what figures did that produce?

[WR1 Bro]

cool Bro - what figures did that produce?

On that run Bob said it was 405/354.

We did a run of 415/465 but I'm not sure why he didn't send me that graph. I'm looking forward to the next figures where the sole intention is to improve the torque albeit at the expense of the bhp.

[dynamix]

Ok - I guess that shows the difference in peak figures versus area under the curves.

Delta showed 297 bhp at the wheels and 330 lb/ft at the wheels for me on a 4th gear run.

Works out at roughly 370bhp & 413 lb/ft

I would love to know how he has managed to get another 30 bhp from Dan's car at the top end - the turbo just runs out of puff

[WR1 Bro]

I believe Bob works on a 22% transmition loss which is how my figures would be derived.

[The Swede]

Why use 22% with this car and other people always say 24% ??

[danr55]

here you go..

398bhp. 427 ft lbs
Fuel V Power
Allowing 22% transmission loss
Air temp 19 deg C
In Gear Acceleration:
30 - 50mph = 2.0 seconds
40 - 60mph = 1.8 seconds
50 - 70mph = 1.9 seconds
60 - 80mph = 2.2 seconds
Total Vehicle Mass: 1650kg
Test Gear 3

[The Swede]

Yeah, but where did the 22% come from.

Spike's car used 24%, then I've heard people using 21%,...

[dynamix]

mine:

30 - 50 mph = 2.1 seconds
40 - 60 mph = 1.9 seconds
50 - 70 mph = 2.0 seconds
60 - 80 mph = 2.5 seconds

versus yours

30 - 50mph = 2.0 seconds
40 - 60mph = 1.8 seconds
50 - 70mph = 1.9 seconds
60 - 80mph = 2.2 seconds

hmmm - close but more work on the map needed

[danr55]

mine:

30 - 50 mph = 2.1 seconds
40 - 60 mph = 1.9 seconds
50 - 70 mph = 2.0 seconds
60 - 80 mph = 2.5 seconds

versus yours

30 - 50mph = 2.0 seconds
40 - 60mph = 1.8 seconds
50 - 70mph = 1.9 seconds
60 - 80mph = 2.2 seconds

hmmm - close but more work on the map needed

interesting the difference starts getting ever so slightly larger at higher speed, would be interested to:

A - see the difference from 80 upwards
B - race the straight of Cadwell on Saturday and see what happens

[WR1 Bro]

Why use 22% with this car and other people always say 24% ??

Because I believe Bob has built a database of results and he believes this is closer to the truth.

[dynamix]

Yeah, but where did the 22% come from.

Spike's car used 24%, then I've heard people using 21%,...

Personal preferences really.

The 24% figure came from engine dyno testing on ONE car versus that ONE car did on the rolling road iirc Simon Norris's EVO.

As we all know rolling road figures are a bit hit and miss so as long you you stick with a % transmission loss then it gives a good guide to improvements - particularly when measuring with delta dash road dyno on the same piece of road (like I do) and similar environment.

In gear times give a real picture of how that translates into performance

Dan - I will datalog your car on saturday if I may to see if I can see where that difference is - it will be interesting to find out why your same spec engine, turbo etc is possible to produce more at the top end.

My map gets a little conservative at the top end as it scares the beejeazous out of me up there and it is a little difficult, not to mention, fairly unsafe to map that top part of the load, revs on the road in the UK I sense some map changes coming on during the day on Saturday

[dynamix]

was (on normal fuel)

3rd gear:
30 - 50 mph = 2.1 seconds
40 - 60 mph = 1.9 seconds
50 - 70 mph = 2.0 seconds
60 - 80 mph = 2.5 seconds

now (which is actually almost the same as the methanol testing)

3rd gear:
30 - 50 mph = 2.1 seconds
40 - 60 mph = 1.8 seconds
50 - 70 mph = 1.8 seconds
60 - 80 mph = 2.1 seconds

Dyno charts:

Runs done in 3rd gear, all on the same piece of road.



Yellow line = as it was with 1/4 tank of Tesco 99 (14C ambient)
Blue & Red lines = position now with the Prodrive Boost Control Solenoid (9C ambient)

No difference on spool up but it definitely holds boost better and as such the gains in bhp are pretty huge

nb: these are wheel figures

[dynamix]

personally I think these figures are too high and are flattering the performance of the car.