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I just sold mine as well, like you wanted to free some funds up as I don't think the 360 TB warrants the £380 I paid including the plate. Would rather buy the eibach roll bars
 

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I just sold mine as well, like you wanted to free some funds up as I don't think the 360 TB warrants the £380 I paid including the plate. Would rather buy the eibach roll bars
I would defiantly agree that the eibach anti roll bars are a better investment if you had to choose between the two.

However, the plate is a clever solution and beautifully made. Almost the smartest component under my bonnet!
 

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Discussion Starter · #4 ·
I would defiantly agree that the eibach anti roll bars are a better investment if you had to choose between the two.

However, the plate is a clever solution and beautifully made. Almost the smartest component under my bonnet!
True.. it does make a neat job of it.

It's hard to quantify what the TB does in words, but I def. wouldn't sell it if I didn't have to.
 
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I don't get the benefits of the larger throttle body, the air still goes through a restriction at the mouth to the plenum which is the same diameter as with the standard throttle body. What's the point?
 

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I don't get the benefits of the larger throttle body, the air still goes through a restriction at the mouth to the plenum which is the same diameter as with the standard throttle body. What's the point?
You're right. However should not be difficult to enlarge the diameter even DIY. That's what I'm going to do for start.

Look at the Scociu post/picture. You might ask him for details. I've seen the same done on a plenum modified by Autodelta (one of the first two 156 GTA 3.75).
http://www.alfaowner.com/Forum/alfa-gta/321087-act-carbon-plenum-eoi-28.html
 

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Exactly. Nice work (despite the gloss paint I personally don't like:)).

You're right about the diameter of course. However that does not bring the bigger TB effect down in my opinion. People reported increased response even without messing with the size.

Anyway If you check the shape of the ITG airbox https://lh4.googleusercontent.com/-4bo2IqtIYCI/UHXNcXfxFPI/AAAAAAAAAcA/_GdQ08Ctz3c/s800/AR156GTA_TB09.jpg it gets from some 100 mm to as little as 65 mm and increases again on the outcome to 78 mm. Would that mean that 65 mm is the limit for the whole air-intake system?
 
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Exactly. Nice work (despite the gloss paint I personally don't like:)).

You're right about the diameter of course. However that does not bring the bigger TB effect down in my opinion. People reported increased response even without messing with the size.

Anyway If you check the shape of the ITG airbox https://lh4.googleusercontent.com/-4bo2IqtIYCI/UHXNcXfxFPI/AAAAAAAAAcA/_GdQ08Ctz3c/s800/AR156GTA_TB09.jpg it gets from some 100 mm to as little as 65 mm and increases again on the outcome to 78 mm. Would that mean that 65 mm is the limit for the whole air-intake system?
I think yes! For more air to flow through a given space, it needs to move faster. If the intake pipe diameter is increasing and decreasing in size, the flow will be restricted and have to accelerate at each pinch point. I'd assume it would be like pinching the hose on a vacuum cleaner. The air flow rate is restricted, so the device becomes less effective. In a car, the 'suck' is constant at a given engine speed, so the same amount of suck is pulling the same amount of air. The narrowest point on the intake path will be the most significant restriction. The walls of an intake tube offer resistance to the flow of air, so ideally, the path the air has to take into the engine should be as, smooth, short and wide as possible. If I were braver, I'd take the air intake to bits, find the various diameters and try to match them all up.

Thing is, some parts in the intake need air moving faster. The MAF sensor measures the effect of air passing over a tiny sensor, the ECU then uses that to calculate the amount of air flowing into the engine through the full diameter of the MAF housing. The MAF size is pretty much stuck as changing the MAF to a larger diameter one with the same sensor would send readings to the ECU which would be inaccurate and suggest to the ECU that much less air is getting to the engine than the bigger MAF is flowing, the engine would be adding less fuel, the lambdas would read a weak mixture and compensate by adding fuel to fix the issue, if the processes isn't compensating effectively, the car runs way lean, the engine melts and you have an expensive paper weight!

On the 65mm restriction of the air filter housing, the shape of the intake pipe may have some clever design work that facilitates the acceleration of air into the housing. Then the wide open space inside for the filter could be designed for the slow air that the sudden opening out gives, that slowing down will create turbulence.

I may of course be talking total tosh and bunkem!
 

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I don't get the benefits of the larger throttle body, the air still goes through a restriction at the mouth to the plenum which is the same diameter as with the standard throttle body. What's the point?
You can mill out the neck of the plenum to the same ID as the Ferrari 360 throttlebody. Thats about the limit of the standard plenum. Its a strange co-incidence though that the ID of the original black plastic resonator section and the air mass meter are the same as the Ferrari 360 throttlebody. Its as if the GTA was designed to have it from day 1, but some Fiat bean-counter said no and so they ended up with the smaller one and the plenum to match. The original concertina black rubber throttle flexi-pipe acts as the reducer. Going 360 TB means the whole intake system from the neck of the airbox lid to the plenum is uniform inner diameter.
 

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...ideally, the path the air has to take into the engine should be as, smooth, short and wide as possible
No. That's why variable intake tracts were invented, because the above is not valid for the entire RPM range, only for the very high RPM range. To have torque on the low RPM range, the restriction is the speed of the air in the intake, hence the need for alonger and narrower intake.
 

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Exactly. Nice work (despite the gloss paint I personally don't like:)).
It's powdercoated, I figured it would last longer. As for the gloss versus crinkle, well, I don't want to go Ferrari wannabe way so I tried to stay away from crinkly. It's also harder to clean, the crinkle finish.
 
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No. That's why variable intake tracts were invented, because the above is not valid for the entire RPM range, only for the very high RPM range. To have torque on the low RPM range, the restriction is the speed of the air in the intake, hence the need for alonger and narrower intake.
As suspected, I was talking total tosh.
 

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I don't get the benefits of the larger throttle body, the air still goes through a restriction at the mouth to the plenum which is the same diameter as with the standard throttle body. What's the point?
The two graphs on the links below show the difference between two AL 3.8 cars, one with a 360 TB and one without!

http://www.alfaowner.com/Forum/alfa-gta/306788-jimbo-s-147-gta-3-8-a-10.html

http://www.alfaowner.com/Forum/alfa-gta/306788-jimbo-s-147-gta-3-8-a-9.html
 
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