MrContro

Hello

What is meant by a 3 port boost solenoid as oppose to a 2 port, obviously one has more than the other but what are they etc.?

Cheers

john banks

A 2 port solenoid is like an electronically controlled tap - one input, one output. Its flow ability is limited in the OEM version, so a restrictor is needed to get the 0.5 bar wastegate actuator tension up to something more interesting.

A 3 port solenoid has one C (common) which can connect to either a NC (normally closed) or NO (normally open) and it can flow either way. The long and the short of it is that in one position, the actuator is connected to the inlet pipe, and in the other the actuator is connected to the compressor outlet.

In both cases a duty cycle switches the ratio between the two.

The beauty of the 3 port is that the actuator can be controlled more precisely because of the ability to switch to either of the extremes from wastegate spring pressure, or connection to the inlet. In the second instance the actuator is disconnected from the boost source, and boost is only limited by the ability of the turbo to spool whilst allowing for the fact that a restrictive exhaust housing will cause the wastegate to be blown open (eg at high revs on a small turbo).

DuncanG

How many electrical connections does the 3-port have?
Can a 2-port be easily replaced with a 3-port, does it need wiring mods and / or re-mapping?

john banks

The plug is almost compatible, I managed to do mine without cutting wires. Yes it needs a remap since the duty cycles required are different.

MrContro

Thanks John,


I heard Harvey talking about a 6 port, what are the benefits, who makes them ?

Cheers

john banks

It was a joke

AndrewC

John,

In your opinion, is it easier to setup the required boost profile with the 3 port solenoid? I know that a 3 port can give better results in the right hands but I want to know if its a bu99er to map.

I assume that as the wastegate opens and closed more crisply with the 3 port you need to reduce the solenoid duty cycle to achieve the same boost?

Andrew...

john banks

Well you are not using a restrictor, so it depends on the thickness of hose you use and how you plumb it in.

I start low and work up on the maximum duty cycles until I am achieving desired boost pressure, and then log what duty cycle is required to achieve boost in 4th gear. Then I used to add a bit 4% to make it just achieve target in 2nd gear. Since I changed to the gear judge code, I just set it so that I get a small (1 PSI) overboost in every gear except 1st - this means it should still hit target in the summer.

It is easier to get just right than a 2 port which is totally rubbish in comparison.

[Edited by john banks - 12/22/2002 10:57:19 PM]

Turbo_Steve

So if I clean my Solenoid, but don't want to mess about with finding a replacement restrictor for the bit of pipe I ripped off when it split, I could just get my car re-mapped and should have a better driving car, AND no overboost in the winter anymore?

I know the VF in the legacy isn't good for much boost, but a nice uniform 1.1bar would be fantastic ( I am guessing that would be okay on the standard injectors and fuel pump and chargecooler, and give about 220bhp)?

David_Wallis

old cars do have a restrictor..

David

Turbo_Steve

Mine doesn't anymore.
The pipe with the restrictor in split, and I replaced it without realising it had a restrictor in.

This, and a dirty solenoid are causing me overboost problems...just enough to have the ECU pull the boost back to 0.8bar after 4500rpms in the summer, but in the winter the car STORMS up to 4500rpms, then slams headlong into the fuel-cut.
This is annoying, frustrating and painful (my neck is killing me) and will eventually damage something either in me or the car. Seeing as I NO LONGER have a restrictor, would a lovely re-map set up for SUL + octane booster / Optimax only and allowing for my lack of restrictor and with a target of 1bar or 1.1bar accross the range fix the problem and give me some more power to boot?
I can't make much boost without sticking a bigger turbo on, which is not going to happen. (long story, but suffice to say right now I feel like parking the car in a ditch and dropping a lit rag into the petrol tank. The words "Money Pit" spring to mind....every time I save up a bit of cash to start modifying, something else falls off / snaps / leaks / wears out.)

john banks

Sorry, cross purposes - I was referring to Andrew's question about the use of a 3 port as an aftermarket boost control solution for cars that use a 2 port as OEM. Can't see why you couldn't remap to suit no restrictor with a 3 port.

Turbo_Steve

That should save me some serious fumbling around in the cold then