My carb setup which resides very close under the green bonnet bulge, means that i will always be sucking hot air into the twin choke carbs,
So

Roughly how much power is sapped by using hot air in the carb?
If it was say, something like 5% power loss, then i would stick with the current setup, but much more i may think about ducting cold air to feed the carb

Any idea's?

steve

I would say more than that. Although I have no specific figures.

I know adding cold air feed to my old mr2 was the best thing I did.

0%-200% somewhere in that range

with out running the car back to back on some rollers in both set ups you never will know

certainly noticed the difference in the blade after I moved the intakes into cold air stream from
[img]
Rescued attachment air filter.JPG [/img] to
Rescued attachment air filter mod.JPG

I raced a landrover, it used to under pink on steep hill climbs although okay on the flat.

By boxing in the air filter and ducting to the outside world resolved all these issues and picked up power, well worth doing.

Since then all my cars have been ducted for cold air feeds.

Manufacturers kept air feeds hot to stop carbs from freezing, not an issue with EFI infact some you turned the air filter inlet to point at the exhaust manifold!

Regards Mark


[Edited on 28/4/12 by mark chandler]

not really answering you question, but on my track day fiesta i fitted a cheap remote max/min thermometer with sensor beside air filter and was supprised when driving at a reasonable speed the actual under bonet temperature wasnt that high above ambient, however rocketed when stationary, if air filter is quite close to bonet i wonder if the airflow would be restricted rather than temperature being the issue as max power require a lot of intake air, have you any photos?

You could find somewear to go for a drive without the bonnet fitted this would give you a chance to test it

There is a sentence in the the Graham Bell Performance four stroke tuning:
'You can reckon on a power decrease of at least 1% for every 7 degree C the intake air temperature rises.

Hope that helps.

Adrian

Cant answer the question.but when the carb freezes you lose 100% of your power.

I just made an air box/pipe/intake at the front of my car (itb's and was the pipercross 600 sausage filter fitted), and the difference is a very very noticable increase in performance (and a huge drop in intake noise but that wasn't the main reason for doing it). The primary reason was the intake air temp readings seen on the ecu and reading up that cold air was free extra power even if only small.

Now whether that's down to cold air going in, resonant frequencies on the intakes or the much debated ram air effect i don't know but i would say it 'feels' far more than 1% power/7 deg of air temp. Obviously not scientific with back to back tests on a dyno, but quite a few areas of the fuel map needed richening afterwards to get the afr's in the ball park again on the data logs. In my mind that confirms that not only does it feel far better, something good is actualy happening!

Ian

I had bed carb freeze on an XR2 simple small tube from exhaust manifold to K&N stopped that
On my 7 I used 100mm flexible extractor fan duct, run from the nosecone to the carbs, cut in half and laid over the piper cross leaving the rear open to the warmer air, this gives me a good cold air feed with just enough warm to stop icing

Why don't you fit a simple cable operated butterfly - leave it fed with cold air from your cold air source and you can switch to a warm air source (from exhaust manifold) when you feel that you need to.

Steve

I find this a very interesting topic as my 2l Pinto engine suffers from drawing in very hot air through a K&N filter fitted atop the twin choke Weber.

Is the solution as simple as fabricating a fitting in place of the K&N to take say a 3" flexible pipe, the other end of which could be equipped with filter and positioned to draw in cool air from elsewhere in the engine bay?

I'm sure there must be snags I haven't even thought of. Any ideas on carb fittings, pipework or filters would be gratefully received.

An air scoop on the bonnet seems like the way to go.

Make sure you have somewhere for the air to leave as well.....

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Originally posted by 02GF74
An air scoop on the bonnet seems like the way to go.

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Originally posted by bumpy

quote:

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Originally posted by 02GF74
An air scoop on the bonnet seems like the way to go.

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Unfortunately I have a classic looking JBA Falcon, like the one shown, and a scoop on the bonnet would definitely not sit comfortable with the look

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My friend had the same worries with his Westfield re. underbonnet temperatures etc.
We tested the theory on a rolling road at Newark kit car show, bonnet on, bonnet off.
Back to back runs showed a difference of 1-2 hp in favour of bonnet off.
Not a true "on the road" test I grant you, but it did show that the difference was small on that particular car under those particular circumstances.

quote:

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Originally posted by Ivan

quote:

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Originally posted by bumpy

quote:

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Originally posted by 02GF74
An air scoop on the bonnet seems like the way to go.

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Unfortunately I have a classic looking JBA Falcon, like the one shown, and a scoop on the bonnet would definitely not sit comfortable with the look

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Yes but boxing around the air filter with louvers in the bonnet would add to aesthetics.

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Has anyone experimented with something like this remote air filter from Car Builder Solutions




[Edited on 10/10/14 by bumpy]

[Edited on 10/10/14 by bumpy]