Lotus Elan Central

by **Paul.P** » Wed 26.07.2006, 21:54

Has anybody noticed during this heatwave, a loss of power ?, car won't boost as quick or as far. Don't know if its me, or somethings wrong ?. Spoke to several people who say there cars nowhere near as quick in this heat, not just lotus's.

by **Dave M** » Wed 26.07.2006, 21:57

ESM may be able to speak a bit more to this, but my guess is the car's computer may control boost when it senses a higher IAT. Even if it doesn't, the car will have less performance in hotter conditions as the intake charge is not nearly as dense. That's why having a rip on a nice, cool evening is so much fun!

by **Dave Eds** » Wed 26.07.2006, 21:58

Mine's been going quicker mate! (not saying much though!)

Maybe its cos I'm getting used to "no brakes" and getting a bit less cautious.

by **Paul.P** » Wed 26.07.2006, 21:59

Dave, whats a IAT ?, is it temperature ?

by **Dovey** » Wed 26.07.2006, 22:04

Intake Air Temperature...

by **Paul.P** » Wed 26.07.2006, 22:10

Thanks Dovey, so am i right in presuming theres a censor to control this ?, & can it be tested to see if its working ok ?

by **TStevens** » Wed 26.07.2006, 22:10

Intake Air Temperature...

Basically the colder the air is the denser it is, and the more oxygen, hence more bang. hotter air is less dense, hence less oxygen being rammed in by the turbo, and not so quick Elan...

The answer can be a spray mister, where you spray cold water over the air intercoolers or onto the intercooler ducts in order to cool the air as it goes in.

by **Paul.P** » Wed 26.07.2006, 22:26

So what your saying basically Tony, is it will be slower in this hot weather ?, it struggled to pull much over 120 early tonight , whereas 4 mnths ago it did 140 & was still going, do you think the hot weather would make that much difference ?

by **Dave Eds** » Wed 26.07.2006, 22:32

So when the air is hot and contains less oxygen does it contain more pollution? hence mine struggles a bit going through Blackwall Tunnel every day in this heat (is the engine choking like I am?).

by **TStevens** » Wed 26.07.2006, 23:32

yes it will be slower, definatley less acceleration, I dont know for certain on your top speed though, or how dramatic a difference it will be. But we all know a slightly cold damp/misty morning can mean a very lively elan.

by **JLSELAN** » Thu 27.07.2006, 00:24

In engine performance parlance it's called heat soaking, and it is a very real phenomenon that robs power (and therefore top speed) whenever inlet charge temp increases above some prescribed limit. Key info to the ECU is the inlet charge temp as this will determine which "map" to use to insure reliable (non destructive) engine performance. As the charge temp increases, other controlled parameters like spark and fuel are adjusted in an effort to keep the engine in one piece :wink:

. In other words, your computer is trying to save the day even if the driver doesn't have a clue!

Cheers, Joel

by **Paul.P** » Thu 27.07.2006, 07:16

JLSELAN wrote: In other words, your computer is trying to save the day even if the driver doesn't have a clue!

Thats very well put Joel ! :lol:

by **DaveT** » Thu 27.07.2006, 07:33

If you have the air con on. Turn it off. If you have the air con on- WHY? Take the roof off!!

by **malbon** » Thu 27.07.2006, 08:22

Yeah - I've had this too. Defo the weather. Used to drain my old S2k like anything and appears the same here. Had a blast home last night at about 10.00 pm when it had cooled down and it felt twice as fast

by **Paul.P** » Thu 27.07.2006, 17:25

Well at least i ain't the only one suffering in this heat !

by **M100 TWO** » Thu 27.07.2006, 17:41

P P are you using an exposed cone air filter?

by **Paul.P** » Thu 27.07.2006, 17:43

M100 TWO wrote:P P are you using an exposed cone air filter?

No, ive got a K&N but its the type that replaces the original !

by **M100 TWO** » Thu 27.07.2006, 17:48

can't blame under bonnet temperature then!!!!

by **malbon** » Fri 28.07.2006, 09:19

Cars just like cool air. Pity its so hard in this country to get dry roads, cool air AND sunshine all in one swoop :-D

by **ESM** » Fri 28.07.2006, 12:23

Just to repeat the earlier remarks and maybe add a little. The MAT sensor (mass air temperature) is used along with the MAP (manifold air pressure) and the volumetric efficiency to calculate the mass of air that will be inducted into the cylinder, with this information the appropriate amount of fuel to give the current target mixture can be calculated and metered into the intake.

In summer when air is hotter and less dense the same volume contains less mass and so the fuelling is reduced proportionately and the power is reduced in turn. This effect, while noticable, shouldn't be massive nor should it reduce the boost observed so I'd say its not simply the reduction of density that is at the base of your issue.

It is possible that the MAT and/or CTS are out of calibration which could cause the car to run perfectly under some conditions and poorly under others. It could be of a symptom of many other engine issues too :roll:

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