Maximum speed changed?

[Anonymous]

Gentlemen,

I have a problem  s:) s:)  My MR2 was able to run 200 km/h last summer (electronic limitation I guess, 6K rpm at the 5th gear). This winter (with different wheels and winter tires) it was around 190 km/h. Now I can get only 180... Testing road is the same, both directions (no wind). What could be a reason? Oil (10W60 used instead of 5W30, but it's HOT now - does it help or just spoiles everything)? Bad gas (I've got 98+ from the place where I usually take 95+)? What else?

Thank you VERY much for your help!

Regards,
Anton Kolomyeytsev

[Anonymous]

Could be all sorts of things.

If it's hot then that's not going to help.  Hot air is less dense than cold air.  Therefore there is less oxygen to burn the fuel with so less power.  Your thicker grade oil will also produce more friction losses.

Other contributing factors could be old oil, more wear on plugs, dirty air filter, dirty MAF, new tyres (change in rolling radius),  old fuel, carbon buildup, sticking brake caliper, wheel alignment, roof up vs roof down.  None of these may be bad, but several imperfections can make a difference.  There is also a chance it's the beginnings of an engine failure, but unless you're loosing a lot of oil I doubt it.  Why did you change to 10W60?

180kph = 111mph.  That's not good for a '2 but it will depend on the road.  Am I right in thinking that EU '2s were electronically limited to 120mph?

[Anonymous]

Probably just the heat, clean your MAF, reset your ECU and try again.

Not really anything else it can be, but check your pre-cats if there still there as it is possible they could be breaking up and clogging your main cat, reducing power.

[Anonymous]

 s:roll: :roll: s:roll:  mrbarney beat me to it. Not being a dumb ass and copying what he said.  s:wink: :wink: s:wink:

[Anonymous]

:roll: mrbarney beat me to it. Not being a dumb ass and copying what he said.  s:wink: :wink: s:wink:

s:twisted: :twisted: s:twisted:

[Anonymous]

I would almost definitely say it was solely down to the different wheels and tyres.

If their sizes changed from the originals then this will affect your acceleration and top speed.

If the rolling radius has increased this will cause the car to accelerate slower and have a reduced top speed as they require more torque to turn them the same distance as the wheels you originally used.

Obviously if they're exactly the same size then this won't be the cause   s:oops: :oops: s:oops:    s:wink: :wink: s:wink: