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?

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]

Originally Posted by Saint aka ML

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]

Originally Posted by Darren69

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.

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]

Originally Posted by 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

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.