Okay I know its a pretty obvious thing..your going to get power loss when it's hot. But i've never experienced the amount of power loss as I have in the 2 compared to other cars. Presumably this is because its mid engine and the extra heat takes its toll on performance.
Anyways thought I would put some numbers to it, to see how much was phsychological and how much was 'real' HP loss. So I thought i'd measure it with my GTECH. The Gtech doesn't measure BHP, rather real world HP after transmission losses etc. Anyways I went out with the car last night, same strech of road, the temp was 2 degrees C. Second gear run, 108 HP.
Tried the same today just after 5, when it was around 13 degrees C and the HP was 98 HP. I knew there was a loss but I never thought that it was that severe.
i would say either your GTEC is wrong in a big way or you have a problem with your car! s:shock: :shock: s:shock:
When I dynoed my car on a very-very hot day, I came up 16hp down on stock s:roll: :roll: s:roll:
Quote from: "krisclarkuk"i would say either your GTEC is wrong in a big way or you have a problem with your car! s:shock: :shock: s:shock:
Why because the numbers are so low? s:?: :?: s:?: 138 BHP is marketing talk.. they all have 108bhp really.. s:lol: :lol: s:lol: No the numbers are actually quite good for a stock MR2. As I said these numbers are not BHP, but HP numbers. The GTECH, unlike a dyno doesn't measure the BHP from the crank, rather the HP that the car is generating after real world losses.
There is a method of scaling the figures to true BHP numbers, but the assumptions are simplistic. But for the 108HP run would roughly translate to 140BHP.
Or were you saying that the GTECH is wrong from one day to the next??
Quote from: "GSB"When I dynoed my car on a very-very hot day, I came up 16hp down on stock s:roll: :roll: s:roll:
That is a pretty massive reduction..12% near enough! has yours got the OEM airbox GSB? At least I know those figures aren't way out !
Has anyone pocketlogged the difference in temp in the induction pipe between a hot and cold day just out of interest....
s:?: :?: s:?:
Quote from: "MRMike"Has anyone pocketlogged the difference in temp in the induction pipe between a hot and cold day just out of interest....
s:?: :?: s:?:
I remember steve quoting a figure of 30 degrees above normal with the elbow removed IIRC... seeing as you have the blitz it would be the same effect i guess.
Quote from: "MRMike"That is a pretty massive reduction..12% near enough! has yours got the OEM airbox GSB? At least I know those figures aren't way out !
At the time it was bog standard. IIRC the air pressure was very-very low at the time too, 950mBarA I think. Obviously that is a significant factor, as was the dirty filter.
just out of curiousity have you removed the pipe from the air box to give it that throaty sound???as i had the same feeling when the weather changed, put the pipe back on and power back. just a thought.
Quote from: "jonboy"just out of curiousity have you removed the pipe from the air box to give it that throaty sound???as i had the same feeling when the weather changed, put the pipe back on and power back. just a thought.
Me or Mike? Mike I think has an Apexi, and I'm running a H&S de-restricted intake pipe. It was standard at the time of the dyno though.
Quote from: "GSB"Mike I think has an Apexi
Blitz
*YUCK!*
i am wondering if it could be the excess heat.
i originally had a vauxhall (no jokes please s:lol: :lol: s:lol: ) with a k&n induction kit and you really noticed the power difference when the weather was hot especially in the lower gears.
Quote from: "krisclarkuk"Quote from: "GSB"Mike I think has an Apexi
Blitz
*YUCK!*
s:lol: :lol: s:lol: Couldn't quite make out if that said Yuck...or Fcuk then Kris! s:lol: :lol: s:lol: No I do indeed have a Blitz, though its not the Intake, it's only a panel filter so I'm not worried about the Filtration. The Panel filter is excellent, very similair to a K&N's mesh design. I think the only reason the Induction Kit is so poor for filtration because it employs the steel gauze as opposed to mesh. So don't worry Kris!
No I haven't removed the Intake Pipe yet..though i'll be replacing it with Mark's intake pipe as soon as I get my hands on it!
Quote from: "MRMike"it's only a panel filter
phew! *wipes brow* s:lol: :lol: s:lol:
The replacement pipe makes the throttle a touch more resposive but nothing out of this world... every little helps though.
Quote from: "krisclarkuk"Quote from: "MRMike"it's only a panel filter
phew! *wipes brow* s:lol: :lol: s:lol:
The replacement pipe makes the throttle a touch more resposive but nothing out of this world... every little helps though.
How so Kris? Responsive as in touch the throttle response? or top end? I would have expected that to have been marginally less responsive at low revs given the larger bore, and the theoretical loss of torque? I'd imagine it's better at the top end though..
Johnboy I used to experience the same thing...My K&N was located right by the side of the engine though. There was no way that thing made any more power at anytime, but it was much worse in the summer.
How are the Apexi people finding the higher temperatures???
top end... seems a bit more responsive. a little louder too, but not by much. Bottom end seems unafected... but the whole car is running funny since i had to put normal shell petrol in s:oops: :oops: s:oops: 87.9p for optimax is just a bit too rich for me! s:shock: :shock: s:shock:
Quote from: "krisclarkuk"top end... seems a bit more responsive. a little louder too, but not by much. Bottom end seems unafected... but the whole car is running funny since i had to put normal shell petrol in s:oops: :oops: s:oops: 87.9p for optimax is just a bit too rich for me! s:shock: :shock: s:shock:
I know i've questioned Optimax in the past..and I haven't bought it for 2 months but ever since i've not used it my car has run as rough as a bears arse. It's lumpy as Hell at idle, and holding a constant rev it's very hesitant. I'm thinking it may be an injector more than anything though. The last batch of petrol was Shell so I wont put that in again. Bp Ultimate seems to be ok
i thought shell had a reputation for quality fuel? s:? :? s:? should i switch to a dirrfernt station then?
p.s never noticed the difference that optimax stuff does, i belive your engine (and ECU) have to be designed to take any advantage of it
They do! Lots of people rave about it.. so I don't know what wrong with mine. Probably could do with an ECU reset considering its been run on Optimax for so long. The petrol debate has been done to death and i'm still no wiser as to what really is the best thing to use. I think i'm just going to stick BP ultimate in as it seemed to like that. Wouldn't use Optimax again for the reasons i've mentioned in previous posts.
Your right you would getter better gains with higher RON fuel if the ECU had an enhanced fuel map in it though.
isnt our engine designed to run on 87 octane? as that's what they mostly fill up with in the U.S...
so, really, we shouldn't see any benefit to using a higher octane rating
Quote from: "MRMike"But i've never experienced the amount of power loss as I have in the 2 compared to other cars.
10hp loss in 1000kg car feels about same as 15hp loss in 1500kg car. We have a light car, so every change feels bigger than in heavier cars s;) ;) s;)
Interesting thread. I posted a LONG time ago (may even have been on the Yahoo board, I can't remember), when we had the really hot weather last early summer about what I thought was a severe power loss above the point where the VVTi kicks in. Travelling to Sheffield, top down and trying to overtake a stupid Transit, I stuck my foot down and got a bootfull below 4500rpm. Above that it felt like someone had attached an elastic band to the car. I have only EVER experienced this in the really hot weather. I had been running up the motorway for about 1 1/2 hours at that point, so maybe the heat inside the engine bay itself didn't help, but either way, since the weather has got cooler, I haven't had it happen again. I was worried as I thought there might have been something seriously wrong with the car (I had only had it about 3-4 months), but no-one on here could come up with an explanation and it hasn't happened since (or not to the severity it did that week). I guess, as you have noticed, must have been down to the temperature.
Will have to see what it is like when the weather warms up again.......... s:? :? s:?
Quote from: "John Woodward"I thought was a severe power loss above the point where the VVTi kicks in. s:? :? s:?
Yep thats exactly how i'd describe it..I hadn't got a clue how the VVTI mechanism worked until Mark told me its controlled via Oil Pressure..I'm no physicist but if it s hotter surely the visosity of the oil is less and thus the pressure is lower???? Maybe that why the VVTi suffers in the Heat?