Leakoff pipes/ spill lines

Datatek · Jul 30, 2023

kermit_rr said:
I get that, just looking at the 2 fools side by side, you can see the difference.. apart from the nasty diesesed smell!!
Still don't get why there needs to be complicated 'spill'.. am i having a mental block? Is it simply because of the high pressure that it can't be simple like petrol and also needs more accurate injection timing?

On mechanically injected diesels, the injector opens under the pressure of the fuel from the FIP at the appropriate time, when the pressure is removed the injector closes under spring tension and the surplus fuel goes into the spill line. On the modern stuff, the injectors are under constant pressure and are opened electronically so I'm not quite sure why there is still the need for spill lines, they do not exist on my petrol injected car. Maybe it's down to seals leaking due to the very high pressures on the diesel.

WhiskyLassie · Jul 30, 2023

kermit_rr said:
It doesn't matter, diesel doesn't use a carburettor

I know that because of the air flow mix wouldn't work but I'm just trying to think when they stopped using carburetors in engines in general. It must be nearly 30 years or so.

kermit_rr · Jul 30, 2023

Datatek said:
On mechanically injected diesels, the injector opens under the pressure of the fuel from the FIP at the appropriate time, when the pressure is removed the injector closes under spring tension and the surplus fuel goes into the spill line. On the modern stuff, the injectors are under constant pressure and are opened electronically so I'm not quite sure why there is still the need for spill lines, they do not exist on my petrol injected car. Maybe it's down to seals leaking due to the very high pressures on the diesel.

Didn't know early ones opened under pressure though i suppose it makes sense now i think about it.

kermit_rr · Jul 30, 2023

WhiskyLassie said:
I know that because of the air flow mix wouldn't work but I'm just trying to think when they stopped using carburetors in engines in general. It must be nearly 30 years or so.

In bikes it was around 2000.
I remember my granddads car has single point injection, essentially an injector over a throttle body so the disadvantages of both and the advantages of neither

WhiskyLassie · Jul 30, 2023

What car did he have, I know in this century some of the sports bikes still had chokes.

kermit_rr · Jul 30, 2023

WhiskyLassie said:
What car did he have, I know in this century some of the sports bikes still had chokes.

i don't know.
My bike is injected and has a choke lever, but it's not really a choke.. injection doesn't need it. In fact it's fast idle adjustment for cold running

WhiskyLassie · Jul 30, 2023

kermit_rr said:
i don't know.
My bike is injected and has a choke lever, but it's not really a choke.. injection doesn't need it. In fact it's fast idle adjustment for cold running

I use it if I wanna **** off neighbours

Grrrrrr · Jul 31, 2023

WhiskyLassie said:
I know that because of the air flow mix wouldn't work but I'm just trying to think when they stopped using carburetors in engines in general. It must be nearly 30 years or so.

1980s, I would say. Prior to that most cars were carb and dizzy.

kermit_rr · Jul 31, 2023

The first clios has carbs, think they were phased out in the mid 90s

Datatek · Aug 1, 2023

Grrrrrr said:
1980s, I would say. Prior to that most cars were carb and dizzy.

My 1986 MR2 has crude petrol injection, 4 injectors but not sequential, all the Fords I ran at that time still had carburetors.

Grrrrrr · Aug 2, 2023

Datatek said:
My 1986 MR2 has crude petrol injection, 4 injectors but not sequential, all the Fords I ran at that time still had carburetors.

My Astra GTE was fuel-injected and so were the Golf GTi's that were around at the time. I'm trying to remember which of my cavaliers switched from carbs to fuel injection. The first mk2 one was still carbs (I recall the vacuum pipe for the advance used to perish) but I am pretty sure the later ones were injection. Pretty sure my mother's 1987 VW Polo was fuel injected too. Come to think of it, the Jaguar V12 in the XJS was fuel injected in the later models too - the one I have out the back is and that was eighties.

So I am thinking it probably started with the higher performance models at the start of the eighties and by the end of the eighties maybe 80% were fuel injected. The rest must have followed in the nineties

Datatek · Aug 2, 2023

Grrrrrr said:
My Astra GTE was fuel-injected and so were the Golf GTi's that were around at the time. I'm trying to remember which of my cavaliers switched from carbs to fuel injection. The first mk2 one was still carbs (I recall the vacuum pipe for the advance used to perish) but I am pretty sure the later ones were injection. Pretty sure my mother's 1987 VW Polo was fuel injected too. Come to think of it, the Jaguar V12 in the XJS was fuel injected in the later models too - the one I have out the back is and that was eighties.

So I am thinking it probably started with the higher performance models at the start of the eighties and by the end of the eighties maybe 80% were fuel injected. The rest must have followed in the nineties,

My XJS was injected and the XR3 Escort was replaced by the XR3i in 1983. As you say, it was the performance models that got FI first as dictated by marketing.

Grrrrrr · Aug 2, 2023

Datatek said:
My XJS was injected and the XR3 Escort was replaced by the XR3i in 1983. As you say, it was the performance models that got FI first as dictated by marketing.

A mate has just bought a Tiger (the kit car). 2.0 Ford engine with carb rather than injection. Apparently it did better on the rolling road with carbs. Maybe the default Ford map wasn't up to much.

Datatek · Aug 2, 2023

Grrrrrr said:
A mate has just bought a Tiger (the kit car). 2.0 Ford engine with carb rather than injection. Apparently it did better on the rolling road with carbs. Maybe the default Ford map wasn't up to much.

The early FI systems were very crude, the main advantage was the elimination of the choke IMO.

Grrrrrr · Aug 2, 2023

Datatek said:
The early FI systems were very crude, the main advantage was the elimination of the choke IMO.

This is only a few years old. Only done 3k miles. Fun little thing although very tight for me to get into.

Datatek · Aug 2, 2023

Grrrrrr said:
This is only a few years old. Only done 3k miles. Fun little thing although very tight for me to get into.

If the FI fails on the MR2, I may end up doing a carb conversion as getting parts is not easy.

kermit_rr · Aug 2, 2023

Datatek said:
The early FI systems were very crude, the main advantage was the elimination of the choke IMO.

some carbs had an automatic choke.. i think the biggest benefit was being able to shut off fuel while the engine is running, which would otherwise kill catalytic converters
i know kawasaki for a while had carbs and cats, with a fancy mechanism to stop the fuel flow through the carb, the catalyst protection system, which was used to stop flow to the jet when overspeed limiter is engaged, there is a misfire or the killswitch is engaged

Datatek · Aug 2, 2023

kermit_rr said:
some carbs had an automatic choke.. i think the biggest benefit was being able to shut off fuel while the engine is running, which would otherwise kill catalytic converters
i know kawasaki for a while had carbs and cats, with a fancy mechanism to stop the fuel flow through the carb, the catalyst protection system, which was used to stop flow to the jet when overspeed limiter is engaged, there is a misfire or the killswitch is engaged

A lot of automatic chokes were unreliable, I modified more than one car to manual choke.

Rubberknees · Aug 2, 2023

Datatek said:
A lot of automatic chokes were unreliable, I modified more than one car to manual choke.

+1 on that years back had an Audi with auto choke. It was undriveable til engine had warmed up

Grrrrrr · Aug 6, 2023

Rubberknees said:
+1 on that years back had an Audi with auto choke. It was undriveable til engine had warmed up

VAG used to have a little wax cyclinder in the coolant in some cars and that used to fail so the choke didn't work. Quick and easy to change.

Leakoff pipes/ spill lines

Well-Known Member

Well-Known Member

Very

Very

Well-Known Member

Very

Well-Known Member

Technician, Bodgit & Scarper Ltd

Very

Well-Known Member

Technician, Bodgit & Scarper Ltd

Well-Known Member

Technician, Bodgit & Scarper Ltd

Well-Known Member

Technician, Bodgit & Scarper Ltd

Well-Known Member

Very

Well-Known Member

Well-Known Member

Technician, Bodgit & Scarper Ltd

Similar threads