Technical Brainstorm session.

[Saint aka ML]

So got new engine.
Plan is 944 St2 engine with water cooling.
Loom from 900ssie together with ECU and 50mm throttle bodies instead of st2 46mm one.
Coils from 900ssie, flywheel from 900ssie. Custom dash.
Will i be able to put st2 map on 900ssie ecu, are they the same ecu? If need be I will do dyno but that will delay the build then by month or so as will then also fit high comp pistons so I dyno one time but good.

Airbox was thinking none with cone filters and have smaller water radiator there so hidden.
Lack of Airbox will it impact torque as I am looking more for that then bhp.

Water radiator will be fitted together with in line water temp sensor that will activate fans if needed so no link to ecu.

Will that work as is or do I need something else do deal with?

[DrD]

I thought it was the inlet tract length and not the filter arrangement that affected torque.
http://www.sigmaperformance.com/torquemonster.html
Happy to be corrected on that

[Saint aka ML]

I was told Airbox as well affects it due to different pressure. Hence asking

[Darren69]

I would say airbox may have some impact too, consider the SBK air box and how that works. Even intake bell mouth size can have an effect. I have the Beast TPO on my monster and these are considered an improvement over the stock S4 ones but the difference is negligible tbh.

[Kato]

Air box is not going to influence anything that you will notice,

50mm throttle bodies .....from what?? there is no 50mm TB's in the configuration you need for that engine, only specials made by motocorse (no longer available) or Kamna, they won't work serve any benefit with street cams or on a motor under circa 115 hp and you will be around the 80hp mark

AFAIK ecu are different

900ss used IAW15M
ST2 uses 16M

Post a pic of the ECU plug/s on the loom then we can tell you which ECU you need

[Saint aka ML]

Ok throttle body size is i think a typo on ducati website re different sizes 2001 ST2 45mm throttle body while 2001 900ss 50mm but in 2002 all are 45mm.

I did also make a mistake in sizes but they seem to be the same.

I have ECU from 900ssie together with loom, key barrel and igniters.
I want to use that if possible as it will fit injectors as well so easy.

[Saint aka ML]

Question remains except doing a custom map can I just flush a ST2 map on to 900ssie ecu as reference map?

[Kato]

Question remains except doing a custom map can I just flush a ST2 map on to 900ssie ecu as reference map?

NO you cannot

[Darren69]

Even Dr Frankenstein's Monster had its limits! lol

[Saint aka ML]

Even Dr Frankenstein's Monster had its limits! lol

Shush :)

Looking at map I guess to safely fire up the 944 ST2 engine on 900ssie map one would need to retard for 2-3 degrees and it will run like a dog but will run.

Then TPS reset and adjust co2 a bit.

[Dookbob]

Thank goodness spares are still available for my carbs.

[Saint aka ML]

Question 2.

So was thinking as no airbox I could have the radiator behind headstock where the airbox would be.

Anyone has experience with ST2 running temperatures? Radiator on it is huge, same size as 916 and so on. Is it needed in that size?

I was hoping that a radiator that is 21cm wide (core would then be 17-18cm wide) would be enough?
Length of such radiator not sure off yet but guess about 24cm so core about 20cm.

As temperatures in UK rarely drop below -10 I guess I could ditch the 50/50 mix and do 40/60 or 30/70 for antifreeze/water to get better cooling and compensate.

Any suggestions as to why not?

Also any suggestion for good, small water radiators?

maybe someone already did put water radiator in that area?

[Capo]

The specific heat of an water glycol mix at 93C
50/50 0.865
60/40 0.905
70/30 0.936

The differences have a marginal effect on cooling.

To size a radiator you need the following
Volume of heat to be dissipated
Fluid flow rate
Operating temperature
Desired delta T
Air temperature
Air volume
Delta P
Face velocity

[Saint aka ML]

The specific heat of an water glycol mix at 93C
50/50 0.865
60/40 0.905
70/30 0.936

The differences have a marginal effect on cooling.

To size a radiator you need the following
Volume of heat to be dissipated
Fluid flow rate
Operating temperature
Desired delta T
Air temperature
Air volume
Delta P
Face velocity

Capo thx for numbers but I do not understand them and also have no experience with temperatures that ST2 engine runs at.
I cannot even find ST2 operating temperature range.

I might have to go with stock radiator for it just in case :(

Any suggestions?

[Dirty]

Do it. If it gets too hot you need a bigger rad. If it still gets too hot you need to move it somewhere with better airflow.

[Saint aka ML]

Do it. If it gets too hot you need a bigger rad. If it still gets too hot you need to move it somewhere with better airflow.

Yes but I need to find out a starting point.

There is no need for me to try it knowing that for example Ducati water arrangement was already marginal so making radiator 50% smaller would just not work.

On the other hand if bike would run fine on air cooling alone then smaller radiator is just a extra that would be handy and I could go smaller.

[marchesini]

Both myself and Capo have put smaller radiators on our S4R bikes with no downsides. Capo has done much more extensive testing than myself but we've both used them in the Italy where the temperatures were 40+. I'm not sure what Capo eventually went with, but I also ditched one of the fans as well and it hasn't blown up ...... yet.

Both ours were custom made by Pace but I'm sure you'll be able to find smaller ones that are standard. Before going down the Pace route, I seem to recall something off a Triumph was a bit smaller. Not sure how you'd make it fit but with everything else you are doing, I would of thought relocating a radiator would be a doddle.

[Saint aka ML]

Thx Marchesini.

S4r runs hotter so if you are good it will be good.

I have found few stock smaller radiators already that would fit perfectly snugly :D. One of the sides from Aprilia RSV (they have split), same for Honda NC30 or Cagiva.

[Dirty]

They do em in different colours too

http://s28.postimg.org/l27gboqvh/Lilac_Group3.jpg

[DrD]

I would have thought since many run the 900 2V in oil cooled mode with 944 conversion, the ST2 with coolant would have no problem with a smaller radiator.
You could run one of the RSV rads without a problem
- choose left or right depending on hose arrangements

[Saint aka ML]

Water cooling more info:
So I had conflicting information here. Some say that I can run ST2 engine as air cooled.

All I have to do is replace the water pump cover with normal one and it is good to go. For aesthetics blank off all the water inlets.

Option 2 I am told I can run without water and that I should just fill with oil instead of water and connect everything to oil pump. Then again replace the cover with no water pump one.

Option 3 have a radiator.

Do options 1 and 2 sound ok?

[Darren69]

Option 2 sounds 'interesting' is the is the oil pump strong enough to pump the oil around the water circuit or does the water pump do that as well and is that up to the job as well? I'm sure I've read of people using option 1 however.

[Saint aka ML]

Option 2 sounds 'interesting' is the is the oil pump strong enough to pump the oil around the water circuit or does the water pump do that as well and is that up to the job as well? I'm sure I've read of people using option 1 however.

Option 2 would go away with water pump only oil pump.

I would prefer option 1 to be correct as then I would still keep water cooling but it would be as an extra so smaller radiator would not cause issues.

[Kato]

Option 1: yes it will work, but not for long, It will run very hot, the barrels may look the same as air cooled but they are no where near as efficient at cooling as proper air cooled barrels

Option 2: As spotted already the oil pump will not cope with circulating through the water system + how will you clean out all the calcium and rust deposits from inside the heads and barrels, if you try to run oil through a water pump it will foam up and turn to sludge

Option 3: with a custom rad............

[Darren69]

The air cooled barrels have oil fed via external pipes, which I'm guessing the ST didn't need?

[jerry]

when i ran my S4 without airbox but with large cone filters instead it revved like mad + mega top end running ,from 8k-10.5k revs that was good but low speed running was iffy and it lost mid range torque ,

tried 6 revised fuelling maps ,,, in the end i deemed it a failed experiment also fuel consumption was like a big V8 ...ouch!!

[Darren69]

I remember reading your thread regarding your airbox removal experiments. From my own experience and speaking to folk, you'd be better off keeping the airbox and maybe changing the velocity stacks. The TPO Beast stacks that I've fitted are much longer and wider than stock, bastard to fit mind you, but they do increase the mid range a little bit and don't affect the overall running at least on the 4v motors. Just a mild re-map on my PC111.