GTRPower

Hey people,

Good thread.

I agree with Randy on this one. Until you've actually driven a Mugen ECM equipped S2000, you don't realise what you're missing. I'm sure Greg Stevens can comment on that too.

The Mugen (or if not available, any other brand) thermostat and high pressure radiator cap is a must. I even recommend them for purely street driven cars. You can never be too safe when it comes to potential engine damage.

About the radiators- I'm pretty sure there are cheaper alternatives on the market- Fluidyne, Ron Davis, etc. Those should be much more reasonable. I've seen Fluidyne ones for the Eclipses go for under $600 out the door. I will probably get a Fluidyne soon- I have a Ron Davis radiator in my GTR, along with the NISMO low temp thermostat and high pressure radiator cap.

Having a water temp gauge is a good idea. I would also recommend an oil temp gauge too.

pfb-

You might end up spending more time (time=money) and money trying to come up with an alternative to the Mugen ECM replacement, perhaps without all the benefits. There are other S2000 ECM replacements available that are less expensive, but I don't think those companies have USA technical assistance services. ECMs are pretty complicated electronic devices. Good luck hacking it...

-Nick

VisualEchos

Forgive me, but are the tempretures you fellas are referring to ever reached in street use? Also, I've heard a zillion things about this Mugen ECU, but no real HP numbers...no dyno sheets...nothing. What gives?

RT

Please explain the benefits of the high pressure rad cap.

cdelena

It is my understanding that the higher the pressure the higher the boiling point. Therefore the cooling system is a bit more effective under severe conditions.

pfb

As I see it:

A lower temperature thermostat will help the engine run slightly cooler IF there is surplus cooling capacity left in the system. If you are running at the kind of engine temperatures that might cause a power loss, the thermostat is already going to stay wide open, thus no benefit. No?

A higher pressure radiator cap will prevent boil-out of coolant and give you slightly more time/temperature before you overheat and start dumping coolant into the overflow bottle. Again, I don't think it will really affect "power loss" syndrome.

I've never experienced a noticable drop of power on the track. Until this thread, I wasn't sure if the effect was very noticable. Possibly I've never run it in high enough ambient temperatures? Possibly the altitude (6000+') is enough to "detune" the engine through reduced oxygen intake/reduced cylinder head temperature/reduced power so that I will never experience it?

Also, you are probably right. You could easily burn up more $$ in dyno time and personal effort than it would be worth considering the Mugen ECU alternative, but once it was done, it would be a $5 mod for anyone who wanted it...

[Edited by pfb on 01-17-2001 at 07:08 PM]

GTRPower

Hey people-

The stock ECM retards the ignition timing almost from the get go. When the engine is dead cold, the VTEC doesn't kick in- that's to allow the car to warm up before really getting hammered. The same thing happens with the ignition timing at operating temps- stock ignition tables, and the degree from which they vary from the baseline, is much greater than the Mugen ECM, which has both a more aggressive ignition map and ignition retard program.

On the street the stock ECM retards the timing significantly when at operating temps. There would be very little power difference from the street to the track when using this ECM. By the same token, the Mugen ECM gives back much more torque, especially at the lower midrange (3K-5.5K rpm) and is also smoother at VTEC transition than the stock ECM.

The reason for the higher pressure radiator cap is due to a couple of things. Coolant does not have a higher boiling point because of the cap- coolant mixes have a boiling point/pressure curve that is only effected by coolant type/water mix, and the cap doesn't change that. What it does do, however, is take advantage of the fact that most coolant/water mixes have a boiling point, under pressure, that is significantly higher than what the stock pressure cap will allow before bleeding into the reservior. Also, going too much higher than stock isn't that advisable either- coolant lines and seals may not take the pressure, especially when old (I had a line literally blow up in my face after a summer morning session at Willow Springs on one of my other cars). Mugen spec's a 1.3bar pressure cap- stock is 1.1bar. That's a difference of .2bar or almost 3psi. I'm sure you can go higher, but at the same time, the higher you go, the more "on edge" the coolant system, in terms of pressure and boiling points, is going to be.

About hacking the ECM- yes, I'm sure you can replicate someone else's ECM modifications for very little money, but since I've seen very, very good tuners blow up engines on the dyno, while tuning them, I personally would prefer not to trust anyone other than the best when it comes to ECM tuning.

Sorry for the long reply!

-Nick

[Edited by GTRPower on 01-17-2001 at 07:56 PM]

cmnsnse

[QUOTE]Originally posted by S2Kguy
[B]Forgive me, but are the tempretures you fellas are referring to ever reached in street use?

2kturkey

[QUOTE]Originally posted by GTRPower
[B]On the street the stock ECM retards the timing significantly when at operating temps.

cmnsnse

Actually the low revs are less prone to detonation only if the throttle is near closed. WOT is letting the engine work its hardest at all ranges.

I think the bog is heat soak related combined with the Idle setting. The sudden surge of hot air is not compensated immediatly. A quick rev before engaging the clutch eliminates my bog problem. Also maybe the cold-non-bog is because of the high cold-idle?

I think the ECU cut back is a different problem than the bog. On really hot days the cut back continues throughout
the rev range, just doesnt give you the kick it usually does.

Prolene

There is also an intake air temp sensor in the intake manifold located towards the back of it.