Hi I have found a sample from YouTube that has the same noise that an Elan I am thinking of getting has. It sounds like when it is on engine overrun rather than the braking itself. The noise I am referring to is the deeper throbbing noise when cornering https://youtube.com/clip/UgkxQha4da-2D3YNdvic-Ul9uONCdzzK2dAe?si=vDiOZuEFyNw7b6P1
Thats engine intake noise when at part throttle and relatively low revs in the corner in the video and is normal especially in a tuned car and especially without the original airbox and duct. Does the car your looking at have the original airbox and ducting ?
cheers
Rohan
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Hi Rohan, no the car has a Ford Works Escort type air filter, see attached pic. The sound sounds almost mechanical or knocking. Will this be causing damage do you think?
Light throttle over-run misfire is (apparently) known as ‘Harry and Willie’ in carburettor tuning circles. Its characterised by high inlet manifold vacuum and lean mixtures and tricky to eliminate. Modern ECUs don’t bother trying, they just give up and stop supplying fuel until the revs drop back to idle or the throttle is opened further - which also has the benefit of improving fuel consumption.
FWIW, your Elan will probably go better with the original intake system, and will sound quieter. The Escort had a lot more under bonnet space than the Elan. You want nice cool air for the intake, and there is the benefit of a small pressure boost if you are drawing air from the plenum.
When I was still competing, I spent quite a bit of time nosing around the pits at other Elans to see why they were faster than me. It turned out it was the ‘nut behind the steering wheel’ at fault, but I did notice that everyone used a plenum mounted filter, trunking and airbox - albeit the larger TTR style airbox that didn’t shroud the rear carb inlet.
Edit: Just FWIW, a couple of GTS style competition Elans off the web -
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That Elan sounds really sweet - and if I am reading the rev counter correctly he is revving it to 8000rpm. I did wonder how he left the Elise in the dust, but on closer inspection of the title I think the Cosworth BDG engine may have helped.
Edit: Even closer inspection of the video, and this time bothering to read the comments, indicates that it is an Exige he is passing, and the Elan has a 272 BHP BDG engine.
Must have ruined the Exige driver’s day.
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Of course, the Exige outweighs the Elan by almost 400lbs.
It does not cause damage as its just carb intake noise. However it could hide other issues which of course need to be checked
cheers
Rohan
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Thank you, I have to admit I was worried that it was mechanical. I will look for a standard Airbox. I guess the other option is to free up the exhaust side and re jet? I was just reading it may be due to fuel slosh in the carb bowls temporally causing lean running for a short time would also explain happening when slowing down or in case of video going around a corner. Thank you for help and advise.
The 40DCOE deliberately has the jet assembly mounted in the centre of the float chamber, so while the fuel may slosh around under braking, cornering and acceleration, the level of fuel seen by the jet’s intakes remains relatively constant. This is of course not perfect, and is a big deal when accelerating as you don’t want the carb to go lean, but frankly for a competition car, who cares if it misses a bit on the over run. My competition Elan coughed and spluttered on the over run like an old tractor.
For a road car, there are different requirements, but the level of ‘G’ force is much lower, and fuel sloshing effects likely to be much less.
Are you using the car in competition?
Hi the car I would like set up as a fast road car, to do occasional track day. I have been looking at Tony Thompson 2inch stainless steel exhausts to free up other side, and the required re jetting. The noise although brief and I’m assuming is due to a lean running situation because of free er induction. A lot of other elans that I see with similar setup don’t make that noise. I would like to understand exactly why the noise is being produced as a deep grinding type noise. Is it just reverberating air? Or piston/s not igniting fuel air mixture in the chamber?
It is part throttle and below the cam rev band noise with an open intake that the video shows and this may be the same in the car your looking at. You probably need to get some help looking at the car if your uncertain and are worried its a mechanical noise
cheers
Rohan
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