new turbo purchase

[zippy]

You two could talk all day about turbos and its very interesting We should have a meeting some weekend at a members house and just discuss cars that are turbo By the way my car came out of the USA with a turbo, have a nice day all.

[NickT]

Just read this.

Have a look at:

http://www.deloreans.co.uk/technical/turbo/

I have a BAE turbo to install but not had the time to install it yet !

NickT

[David Gentleman]

None of that mentions timing though. What does the BAE kit do about timing? Do they simply say retard the timing? Remove the vacuum advance? Thats the main thing that causes knock, not fuel. You know this as an engine can be forced to knock with no boost running through it, and running rich, so it proves that boost and fuel are not the dictating factors.

[Tourettes Tony]

your right david, this is probably another reason why people remove the kits. the set up just tells you about enrichment under boost on one, the timing could be done by restricting the advance but by how much. Locking the bob weights are favourite on this, which incidentally is on the original fitting instructions from bae TT

[David Gentleman]

MSD all the way then I reckon. Easy fix, if it don't work, sell it again :lol:

[Tourettes Tony]

nice one :lol: but given enough time i will be able to sort it out
cheers tony TT

[David Gentleman]

Am I right in thinking there is nothing on the Delorean Bosch ecu that controls fuel pressure according to load?

On the Escort RS Turbo which also runs K-Jet there is an electromagnetic actuator which controls the lower chamber pressure, as the ecu uses an amyl valve which monitors boost pressure and alters the current supplied to the actuator, thus increases the fuel pressure. The Audi Quattro's also ran this type of affair..

[zippy]

Seen your wed site its nice one. I think if you spend enough money on any think you can get it perfect but us being dmc owners we are not like that at all we are on the cheap.Are just like the channels.

[NickT]

David Gentleman Wrote:None of that mentions timing though. What does the BAE kit do about timing? Do they simply say retard the timing? Remove the vacuum advance? Thats the main thing that causes knock, not fuel. You know this as an engine can be forced to knock with no boost running through it, and running rich, so it proves that boost and fuel are not the dictating factors.

Hi David,

The BAE Instructions instructs you to lock the weight in to suppress the second stage mechanical timing.
The result of this that the maximum advance is now approx 23 deg BTDC at 2500.
I can email you an advance curve or you can see it at:

http://www.deloreans.co.uk/technical/ma ... ystems.pdf

Page 212
PDF document page 14 of 54

The Hobbs (or pressure switch set at 1lb pressure) just shorts out the o2 sensor input to the fuel computer to run the duty cycle to give maximum pressure.
Some say to wire in the cold start valve to come on at the same time but the fuel equally distributed to the cylinders is always debated.

I can re-scan in the BAE Instructions I have later on this week as I will be working on site most of this week.

NickT

[David Gentleman]

See 23 degrees is loads for on boost. On my old GTA, that used to run 16 degrees at 6psi and above, and thats right on the edge of knock.

It wants to be about 16-18max, on boost from say 2.5k upwards.

[David Gentleman]

NickT Wrote:The Hobbs (or pressure switch set at 1lb pressure) just shorts out the o2 sensor input to the fuel computer to run the duty cycle to give maximum pressure.
Some say to wire in the cold start valve to come on at the same time but the fuel equally distributed to the cylinders is always debated.

Yep, that will increase the duty, but not the actual 'pressure' yes?

Thats the other issue, you open the injectors wider, but the now higher than atmospheric inlet manifold pressure is now trying to 'push' the fuel back in the injectors...

[Tourettes Tony]

so really the advance should only be 5 or 6 degrees from static ? TT

[David Gentleman]

Tourettes Tony Wrote:so really the advance should only be 5 or 6 degrees from static ? TT

If thats what the base timing is, then yes. Ive just compared a couple of GTA maps I have here running on standalone and they are all running 16-17 degrees at anything above 120kpa (about 2psi boost)

[Tourettes Tony]

right il give it a go, i remember nick saying about 18 a while back, il lock the weights and see how that goes TT

[NickT]

David Gentleman Wrote:

NickT Wrote:The Hobbs (or pressure switch set at 1lb pressure) just shorts out the o2 sensor input to the fuel computer to run the duty cycle to give maximum pressure.
Some say to wire in the cold start valve to come on at the same time but the fuel equally distributed to the cylinders is always debated.

Yep, that will increase the duty, but not the actual 'pressure' yes?

Thats the other issue, you open the injectors wider, but the now higher than atmospheric inlet manifold pressure is now trying to 'push' the fuel back in the injectors...

Interesting stuff this !

The fuel injection system is mechanical KE-Jetronic. The injectors are not electronically switched but are like old mechanical diesel injectors.

The KE-Jetronic is the one with the bleed off valve at the fuel distributor controlled by a fuel computer using sensory information from the o2 sensor. The pressure bleed off valve usually oscillates around the 45-50% duty cycle (if original base fueling is setup correctly).
If the oxygen sensor or the input to the ECU is shorted the duty cycle goes to approx 85% resulting in a higher pressure at the fuel distributor:

Page 151
(PDF page 25/70)
http://www.deloreans.co.uk/technical/ma ... ystems.pdf

It would be desireable to add EFI to the engine but this will load up the insurance premiums.

The static timing on the D is 13 BTDC so maybe retarding it to 7 BTDC would be a safer starting point.

The system pressure tolerance is between 4.5 and 5.2 Bar by the primary pressure regulator. Maybe upping the pressure from the standard 4.7 to 5.2 would give better fuelling at higher revs/ on boost.

NickT