Price...?

[Anders Dinsen]

Are you kidding?? 

Got mail from Pollitecnic now

... That amounts to just about the same as winning the lottery!!
Politecnic are RENOWN for not answering mail!!! 

Maybe they have heard that everyone in Norway are billionaires and spend vast amounts on their cars?
(I'm laughing AT YOU, not TO YOU.... or is it the other way???)

[Oskar]

I might have a spare 505 turbo manifold if you want me to check?

[RazorbackNOR]

Yes please, would you.....? 

What about throttlebodies to fit on the manifold, will only the 505T throttlebodies fit, or others.....?

[krede]

With a bit of grinding and welding, it should not be too difficult to fit another throttlebody on the manifold

[RazorbackNOR]

He he, shall think about this one,

'

IMHO 45mm tb's are too large for an engine that revs out at 6300rpm.


7000dkr is A very reasonable price for both Tb and EFI

But you better then anyone should know that the 505Ti TB is 55mm Krede.... 

[krede]

Yes i do... but I am using FOUR! 45 mm tb's (one for each cylinder) and the Turbo injection only has ONE 55mm Tb to feed them all. 

[RazorbackNOR]

HOLY shit.... then I see.... I thought only one 45.... hehe
But how about syncing all fours and correct airflow through them?

[krede]

That's no problem.... all the synchronizing that is needed is for the two set (of two) throttle plates to be aligned.. you do that with a vacuum  gauge just like you do with weber carbs etc....
Fuel mixture and so on, is all done by the ecu.

[Anders Dinsen]

Razorback - there's two different ways to do the throttle: You can have a throttle per cylinder, or you can have one at the end of a plenum manifold.

The advantage of having multiple throttles for the auto hobbyist is that it can be made as a bolt on replacement for Weber DCOE or similar sidedraught carburettors. Performance wise there isn't much to gain, but I've heard that throttle response can be made better with a throttle per cylinder.

Engine management wise multiple throttles are operated differently from plenum manifold systems. The difference is that if you have multiple throttles, you cannot reliably measure the pressure of the air going into the cylinder. If you have a plenum manifold, the ECU can measure the air pressure in the manifold and use that to calculate the amount of fuel to add. This comes from basic thermodynamics:

pV = nRT

p is the manifold absolute pressure, V is the volume of air taken in per revolution, and T is the air temperature. R is a constant, and n will then be the number of air molecules sucked into the cylinder. Using a factor, the amount of fuel to add can be easily calculated.

An ECU with multiple throttles can't do this as it can't measure the pressure - if you want to measure pressure, you need air which is not moving (at least in principle), which can't be said about the air that passes the short piece of manifold into the engine. Instead the ECU estimates the amount using information about the rpm and the throttle position.

Properly tuned, either solution can be made to work well, but I think the plenum solution is favoured in production cars because it adjusts better to engine wear.

To confuse you completely, I have to add that the 505 Turbo measures air flow differently: It uses an air flow measurement device located in the inlet. Such a device would be compatible with a multiple-throttle design, but wouldn't make sense as these devices inherently reduce air flow a bit, and if you are going for multiple-throttles, you are trying to achieve performance.

--- End of engine management lesson ---