I don't think this has ever been asked straight out, so I'm going to do it:

Does the performance of the S2000 go to hell when the weather gets hot (80s, 90s, high humidity)?

I know the issues with hot air vs cold air, etc. but I have never had the performance of a car change when it's hot the way the S2000 does. Driveability is still OK, but it's just not the snorting beast it is in milder temps.

Part of the reason I ask is that I have the SC and I was initially blaming the check valve (or "POS check valve" as it is sometimes known). I have even had the dealer check to see if any error codes were thrown (none) and swapped out the MAP sensor (no effect). Now that summer is in full force around here, I am coming to the conclusion that this is just the way the S2000 is in hot weather - does anybody else agree? Or am I just a victim of the "POS check valve"?

Would the Mugen thermostat and radiator cap help this problem?

 

This has been reported many times. Especially from the owners who have been through last summer.

I took delivery of my car last year on 08/21/2000 during the afternoon. We were hitting(or nearing) the 100 degree mark in Texas and the car felt so sluggish in the afternoon heat during my first month of ownership. The first thing I noticed is that performance was way better in the 70 degree mornings.

The Jeckyl and Hyde reared its ugly head again this summer.

I don't have any experience with the aftermarket Radiator Cap, Thermostat items. But you might try searching the "Under The Hood" section of this board.

 

Dude I have the same issue...ever since I have had my car it has been over 100 degrees here every day in Phoenix...and at night it only gets down to like 90. The problem is when I first testdrove my first S2k a few months ago it was like 70 out and man she was a rocket...then I ordered mine and by the time it came in it was 100 plus every day and man is there a difference...I have never seen a car so effected by heat before...it's like she doens't even try to get up and go...

 

I would think it's not just an issue with the S2K. Doesn't extreme heat/humidity affect other cars as well? (more so with some cars and vice-versa?)

 

[QUOTE]Originally posted by MHK S2000
[B]I would think it's not just an issue with the S2K.

 

Every car, from my S2000 to my Civic Si, is affected by the temperature. Hot air decreases performance, our engines LOVE cold air. Just enjoy the drive to work in the early morning when its in the 70's or so, because for the next couple months, thats the best you'll be able to do. The best time of the year is the fall - some chilly days out with no snow / rain.....Your engine loves it, especially if you have a CAI

 

Not to mention compressing air heats it! Rocketman, your taking hot air and compressing it making it even hotter air. And I think their is a consensus that the stock ECU really holds the car back when it encounters high intake air temperatures. This is to prevent detonation (exacerbated, again, by FI). IMO you are getting exactly what I would expect from a small displacement FI motor w/no IC (you don't have an cooler do you?). The fact that it is the S2000 is somewhat irrelevant. If it was a turbo or SC Miata w/no IC I'd expect the same behavior.

If it were me, I'd make it a priority to install an IC setup. That's not a cure all, you'll still heat soak sitting around in traffic in hot weather, but at least once your moving things will get better quicker

 

I have just seriously started thinking about an intercooler and have started researching this. Problem is there is no "off-the-shelf" IC for the S2K right now, so it would have to be a "one of a kind" design (costly ).

I know the SC heats the air as it compresses it, but still.... That's why I wanted to hear from others - I finally have enough miles in the heat to have concluded it's the way the car is, SC or no SC.

 

[QUOTE]Originally posted by MHK S2000
[B]I would think it's not just an issue with the S2K.

 

My Prelude runs like ass in the summer. Just the other day a first Gen RX7 (130HP) was almost keeping up with me. I was embarrassed. Its not just the S2K.