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Discussion Starter #1
The GTV is going in to probably be re jetted to hopefully sort my lumpy running saga so I'm thinking this might be a good time good time to replace the air filters before it goes in. I'm looking at the 30mm trumpets and Pipercross filter from CA but I can't find much info on doing this or other mods to Alfetta's. Not sure if this is due to generally less info on the Alfetta's or whether stock advances over the 105's (though I can't see where, my early GTV has a very similar cylindrical set up) mean after market gains are negligible?

Any tips?
 

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The previous owner did this to my car, I think if you team it up with manifolds and an exhaust could be a little gain. They look good and the car will sound throatier I guess.
 

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I've got a Pipercross without trumpets and cant say I noticed any difference to performance - however it does make a lovely sound, its not like a loud droning exhaust which is tiring but rather something you can turn on and off as you want, as far as I understand the standard filter set up is fine but the thing that makes a noticeable difference to performance is having a cold air inlet
If you want some lovely intake noise fit the Pipercross but you might sacrifice a tiny bit of performance - if you want the best performance I would fit the standard airbox with a clean filter but modify it to have a cold air inlet.
I love the noise so I'm sticking with the Pipercross, whatever you do do it before you get it rejetted, mine runs a little weak but I get 30 mpg so not a problem.
Best value performance enhancer is to fit an electric fan and bin the old one, even then its barely noticeable
 

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I'm with Joe90 on this.

I've tried all kinds of things on my Alfetta over the years, but have never seen much improvement from fiddling with air intake/filters. The gas flowing (inlet/exhaust) on these cars is actually pretty good. A couple of points though...

1. Having a long inlet tract (filter inlet tube, inlet manifold, carb throats) creates more sustained momentum in the air intake - a longer 'tube' of air moving more steadily towards the inlet. This momentum improves volumetric cylinder filling at lower revs - so removing that inlet tract and using 'pancake' filters or trumpets/meshes might give a little more top end (6000 rpm) power, but at the expense of the wonderful full range torque of these amazing engines. Great for a race car, but not so good in everyday driving, where you're not permanently at 6000rpm! Airflow constriction is unlikely to degrade performance until you're at high revs (i.e. high air demand).

2. Mine has the cylindrical air filter, which has a really big filter area and therefore minimal pressure drop across the filter element. But the metal tube that runs through the centre of the cylindrical housing has surprisingly few/small holes in it. I cut some big slots in this, which must help a bit, but without destroying the integrity of the inlet tract.

3. Some people use trumpets and meshes but they offer almost no filtering, so inlet wear will be greatly accelerated. Again, not a problem on a race car that does relatively few miles between engine rebuilds, but I'd never put them on a road car.

4. Pancake filters are drawing warm air from the engine bay, which is less dense than the cold air collected by a standard filter set-up. This reduces the mass air charge on each stroke which in turn reduces maximum achievable power, especially as things get hotter. Race cars usually have additional ducting to bring cold air from outside the engine bay, right up to the pancake filters.

Of course, if you just want to make a fun noise and aren't so worried about optimising driveability and road-going performance then pancake filters like K&Ns or Pipercross are quite fun - but people tell me my Alfetta sounds great just how it is!

A much bigger influence on Alfetta performance is camshaft timing...

Each to their own!
 

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Two wonderful articles on inlet trumpet length and effect on torque.

Note that everything is about torque and where in the rev range it is. BHP is just a mathematical calculation of torque and rpm and the formula is:-

BHP = (RPM x Torque) / 5252.

Chase peak torque at or near the rev range that you normally drive for a road car and peak bhp for a track car.

The articles are here:-

Blog - Emerald Adjustable Length Intake Trumpet Development

https://nwmobilemechanicdotcom.word...ciency-with-inlet-runner-length-pulse-tuning/
 

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Two wonderful articles on inlet trumpet length and effect on torque.

Note that everything is about torque and where in the rev range it is. BHP is just a mathematical calculation of torque and rpm and the formula is:-

BHP = (RPM x Torque) / 5252.

Chase peak torque at or near the rev range that you normally drive for a road car and peak bhp for a track car.

The articles are here:-

Blog - Emerald Adjustable Length Intake Trumpet Development

https://nwmobilemechanicdotcom.word...ciency-with-inlet-runner-length-pulse-tuning/
Interesting stuff - not sure if you could squeeze 300 mm trumpets under the bonnet Simon - maybe something like this - thats a stunning Lancia BTW
 

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Discussion Starter #7
Yes, very interesting reading, maybe I could cut some MadMax holes in the bonnet?!

I think I'll stick with standard if there are no noticeable gains and I've recently bought a new standard filter. My first GTV had pancake filters but I took them off I didn't like the flat spots lower down the rev range and I didn't like the trumpets I bought for the Spider as they were too loud, standard it is.
 

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For reference this is what I have, I don't notice any flatspots as such, so from what everyone has said above, is the air too hot in my engine bay unless I get some extra air in ?
 

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Its a funny old thing, but the more you learn about cars, the more you learn how much you don't know about cars..

Old Alfa's are a pretty well designed car, subtle mods or improvements are best for road use.
 

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Hows about this? Bought for my 105 due to concerns over space for a tilton pedal setup, I've now got hold of some shorter tilton master cylinders, so would part with it - period correct too... Colombo Tecni-Filter
 

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For reference this is what I have, I don't notice any flatspots as such, so from what everyone has said above, is the air too hot in my engine bay unless I get some extra air in ?
Carb'd Alfa's love cold air so the more you can get in there the better - just take her out for a drive on a cold crisp winters day and you'll know what I mean - don't know about the Coupe's but there is enough room on the Spider to run a cold air duct in from behind the grill if you remove the rather large and unnecessary expansion tank (I replaced mine with a much smaller bottle). Its not going to win any concours but that doesn't concern me, in fact I'm thinking about how I could force more cold air in - maybe fit a small fan ... I love fettling...
I don't get flat spots from my Pipercross either
 

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Its a funny old thing, but the more you learn about cars, the more you learn how much you don't know about cars..

Old Alfa's are a pretty well designed car, subtle mods or improvements are best for road use.
Spot on. The biggest mistake that people make is to assume that the engineers who designed these cars were idiots, or just got a lot of things wrong. On my Alfetta saloon, I think Alfa got a heck of a lot of stuff right: the engine, suspension, steering and brakes put plenty of much newer cars to shame.

So I agree with you - start with the assumption that these are great cars and make small mods that capitalise on modern technology (Iridium spark plugs, contactless ignition, top quality silicone bushes, etc). The Alfa engineers would almost certainly have used these things if they'd been available back then.

Thought for the day: most of what goes wrong with an old Alfa are things that the owner did to the car, not things that the Alfa did to the owner.

Improve with care...
 
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Discussion Starter #13 (Edited)
Spot on. The biggest mistake that people make is to assume that the engineers who designed these cars were idiots, or just got a lot of things wrong. On my Alfetta saloon, I think Alfa got a heck of a lot of stuff right: the engine, suspension, steering and brakes put plenty of much newer cars to shame.

So I agree with you - start with the assumption that these are great cars and make small mods that capitalise on modern technology (Iridium spark plugs, contactless ignition, top quality silicone bushes, etc). The Alfa engineers would almost certainly have used these things if they'd been available back then.

Thought for the day: most of what goes wrong with an old Alfa are things that the owner did to the car, not things that the Alfa did to the owner.

Improve with care...
You're so right and I think this is the best advice I've heard, though it's taken me a while to realise it. If I'm honest and look back a lot of my 'issues' ( which most will be familiar with!) have come about after my constant fettling and "improving", if only I'd left things alone I'd much happier and much better off but maybe a bit more bored?

Maybe it's something about Alfa's though, I've got a few other makes which I dont touch and have a 'if it's not broke don't fix it' rule as on the whole they run without fault!

I do love a good Alfa fettle though:thumbu p:
 

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Spot on. The biggest mistake that people make is to assume that the engineers who designed these cars were idiots, or just got a lot of things wrong. On my Alfetta saloon, I think Alfa got a heck of a lot of stuff right: the engine, suspension, steering and brakes put plenty of much newer cars to shame.

So I agree with you - start with the assumption that these are great cars and make small mods that capitalise on modern technology (Iridium spark plugs, contactless ignition, top quality silicone bushes, etc). The Alfa engineers would almost certainly have used these things if they'd been available back then.

Thought for the day: most of what goes wrong with an old Alfa are things that the owner did to the car, not things that the Alfa did to the owner.

Improve with care...
Agreed - I'm always impressed with the amount of "engineering" that has gone into my Alfa, all that aluminium and alloy beautifully sculpted, not many other cars (excluding exotica, and some of them were pretty crude) had the same sort of thought put into them, my fettling has always been along the lines of improvements in reliability such as e.ignition, relays,electric fan, better tyres, uprated bushes etc, having said that it can be reverted back to standard without much effort - my Pipercross is unlikely to be as effective as the original airbox but the sound is a bit addictive....
I'd just add things that go wrong are also things that should have been maintained but haven't, its 40 years old FFS; Alfa's poor reputation came later with bad steel and electrics which were a bit thrown together and overly complex and dealers who didn't give a monkeys so the cars were badly maintained - shame but then many manufacturers were in the same boat, that's why our once great motor industry went down the pan and now we just make cars for other people - what a comedown
 

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I feel it is a bit of a shame that the responses have focussed on the impractical 300mm ram pipes. If you read the articles the difference of 20 - 30mm change of length is very marked and an 80mm trumpet on the Zetec was a significant improvement over the 40mm. If you had room for the 170mm you would fit that all day long and you would definitely notice that on the road. Real feel of improvement not just psychological.

What I was trying to get the OP to think about is how does he know that his length ram pipes will be right for his valve timing and capacity. For example will 30mm be worse than standard and will a simple change to 50mm be significantly better than both.

Also wqhen buying ram pipes flow bench and rolling road testing suggests that in almost all cases rounded ends produce better results than flared end even though (due to manufacturing dificulties) rounded ends are far harder to obtain.

Example rounded end:-

http://www.ebay.co.uk/itm/54Mm-Poli...hash=item4cee084295:m:mEboP4UHGzrnueU8klVyb9g

Flared end:-

http://www.ebay.co.uk/itm/Weber-40-...007328?hash=item3d1ac33b20:g:x84AAOSwxehXOzfa

Don't get me wrong; Alfa engineering of this time is amazing doing complex quality stuff that others wouldn't put into cars of equivalent market place but it is simple things like getting the wrong length, flared instead of rounded end and too much hot air in the intake that will make people say things like Alfa got it so right that ram pipes won't bring any benefit. They can and will but it is not as simple as just picking any old length and bolting them on.

A quick look on eBay and you have lengths and end as follows:-

16mm flared
26mm flared
38mm flared
50mm flared
60mm flared
75mm flared

Who knows which will work "best" and "best" is a measure of what the OP hopes to achieve. Does this reinforce "leave it alone", "do it by trial and error", "do it but use a rolling road" or "just do it and enjoy the wonderful induction sound." Each to their own but do take time to understand what effect ram length can have, why and what the options are for deciding what is right for you.
 

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"I feel it is a bit of a shame that the responses have focussed on the impractical 300mm ram pipes"

It was meant to be a joke... getting cold air into the carbs will make more difference than messing with trumpets unless your building a racing engine, at 115 bhp the difference is tiny -
Best - keep standard box with cold air intake -
Not so efficient but lovely noise - fit a Pipercross or somesuch,
The louder the noise especially the exhaust the faster it will go especially if you have a Corsa/Nova............FACT!
 

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Carb'd Alfa's love cold air so the more you can get in there the better - just take her out for a drive on a cold crisp winters day and you'll know what I mean - don't know about the Coupe's but there is enough room on the Spider to run a cold air duct in from behind the grill if you remove the rather large and unnecessary expansion tank (I replaced mine with a much smaller bottle). Its not going to win any concours but that doesn't concern me, in fact I'm thinking about how I could force more cold air in - maybe fit a small fan ... I love fettling...
I don't get flat spots from my Pipercross either
could you show us a picture Joe? I have ram pipes and pipercross socks and reckon the difference is more about character than absolute power. it seems more free flowing etc. Ive seen some cold air arrangements but would like to see how youve done it.
 

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Discussion Starter #18
could you show us a picture Joe? I have ram pipes and pipercross socks and reckon the difference is moe about character than absolute power. it seems more free flowing etc. Ive seen some cold air arrangements but would like to see how youve done it.
Ditto, My cold air feed is basically a piece of flexible tube from behind the grill to the filter, I'd like to see other more efficient set ups.
 

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Ditto, My cold air feed is basically a piece of flexible tube from behind the grill to the filter, I'd like to see other more efficient set ups.
Thats pretty much the same as mine - I used mini heater trunking to run from where the horn sits to feed the end of the Pipercross - first time I modified the original airbox to have an end feed (like the coupe) and attached the trunking to the end, I had to remove the expansion tank (the coupe isn't a problem) and replace it with a much smaller bottle then fed the overflow pipe into the top of the bottle.
I'm sure that is the most efficient set up (especially if you open up the holes in the centre pipe in the airbox) but I fancied the intake noise from a Pipercross so the trunking stayed in place to feed air to the end of the filter - its not very neat and I'd like to build a proper airbox so the filter doesn't suck hot air in from the engine but then I wouldn't have the induction roar... quandary
Hope you get the idea, Mr Rhubarb, I'm reluctant to post up pics because its unfinished business and TBH looks a bit of a bodge - if you could find a coupe airbox then you only need to change the bottle on the Spider, I think the LHD ones are OK because the bottle is on the other side?
 

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Hope you get the idea, Mr Rhubarb, I'm reluctant to post up pics because its unfinished business and TBH looks a bit of a bodge - if you could find a coupe airbox then you only need to change the bottle on the Spider, I think the LHD ones are OK because the bottle is on the other side?
yes, thanks, I think I get it. Mine is pre-expansion tank so nothing to worry about there. There is nothing to impede air from the standard metal duct thing that runs from the spider lower grill area and the trumpets However, yes, the air will heat up - one day I might try to measure it: I think you get get cheap thermocouple loggers these days. The question is whether the temp difference between the intake trumpet location and the metal duct makes additional plastic ducting worthwhile.


I like the trumpet asthetic and figure that the old gta race cars had those trumpets for a reason, but totally take the hint that my somewhat random tract length and flared ends are miles from optimised. I need to get a power measurement for other reasons this week, so therefore will be able to report on the difference when I (one day) get something better.
 
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