[Healeys] Exhaust system advice needed

[Oudesluys]

If it is a properly designed freeflow exhaust you may. What I wanted to 
get accros is that the surface area of the exhaust opening being smaller 
than that of the carbs does not say anything. The speed of the exhaust 
gasses passing is a lot higher than on the carb side so you cannot 
compare. Similarly the exhaust valves are smaller than the inlet valves. 
A stock engine needs a certain amount of back pressure and resonance. If 
you reduce the back pressure to zilch it will not function properly 
without other mods to at least valve timing, carburation and ignition curve.
I have done enough tuning in my time on a dyno on many engines to have 
found out.
Kees Oudesluijs
NL


Eric (Rick) Wilkins schreef:
> I understand what you're getting at. The "what" is that 50 years later 
> we know that a Healey came from the factory with a fairly restrictive 
> exhaust system. We also know that by increasing flow, we can gain a 
> bit of added horsepower--without changing anything else.
> Sure, with newer cars being tuned pretty well from the factory, gains 
> from a simple exhaust "upgrade" are very limited. It's not rocket 
> surgery.
> Get a dyno, measure a stock spec Healey, and measure one with a 
> freeflow exhaust. I'd bet that you'd see an improvement.
>
> On Sep 10, 2009, at 1:53 PM, Oudesluys wrote:
>
>> Yes, so what?
>> Kees Oudesluijs
>> NL
>>
>>
>> Eric (Rick) Wilkins schreef:
>>> I'm pretty sure that in the case of a factory Healey, the added flow 
>>> is going to give an increase in performance as the stock 
>>> system--BN4-BJ7--is smaller than the opening allowed by the carbs.
>>>
>>> Wilko
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