Fuel Injection build.
Posted: Wed Sep 20, 2017 6:21 am
Fuel Injecting a 1040cc Imp Engine
After a Rolling Road session it was clear that the 2 x 1 1/2” Stroms had very poor mixture control and were restricting peak power.
A manifold with four independent runners and Throttle Bodies would have better mixture control, increase power and improve economy.
The manifold design process has been described in a previous post.
viewtopic.php?f=4&t=716
This write up is to help anyone considering Injecting their Imp and will be kept brief by using photo's and parts description. Please study the photo's carefully for build details.
So starting at the front of the Car....
Fuel pumps are 2 x Walbro 190LPH in-tank pumps, on a “mounting pipe” as shown. The assemblies are threaded down through the filler cap and the pump “mounting pipe” brought back out through a 10mm compression fitting in the roof of the tank.
The original pump suction pipe is now the return from the fuel rail, the vent pipe continues as the vent, the “mounting pipe” can be seen between the two. There is no “swirl” pot as the tanks in the Davrian are quite deep, I haven't noticed any fuel starvation even with low fuel and hard acceleration!
The return from fuel rail to left or right tank, is selected by a 3 way LPG valve, VSV12 from BioTuning.co.uk and is mounted on the Forward Footwell bulkhead.
Engine sensors:
The crank sensor is from 1995 1.3i Ford Fiesta and mounted on the front of the Timing case. The 36 – 1 toothed wheel is from Trigger Wheels and can be seen sandwiched between the crank pulley and its mounting flange. The Distributor blank is an aluminium bar turned to the correct diameter, 50mm long with 2 O ring grooves and a threaded hole for the “strongback”.
The Wasted spark coil pack is from a 1995 Mk3 1.4 Ford Fiesta and is mounted on the side of the crankcase above the Dip stick.
The Coolant Temp sensor is mounted in the boss next to the dashboard temp sender and is a standard coolant sensor.
Air Temp sensor is a standard “white” sensor and is glued into the lower plate of the air filter.
The Throttle position sensor was included with the throttle bodies from a 2002 Triumph 600cc Speed Four.
Injectors are from the above throttle bodies as is the Fuel pressure regulating Valve
The plastic fuel rail from the Triumph was not used as the Imp's exhaust is directly under the inlet manifold, instead a Stainless fuel rail from an Audi A4 2.0 petrol was shortened to fit.
A wideband Lambda sensor is essential, it would be almost impossible to tune the injection system with a narrowband sensor and would be difficult to use the Megasquirt Autotune facility and Closed Loop System, an Innovate LC-1 wideband AFR sensor is used and connects directly to the Megasquirt ECU.
All the components are assembled as per photos....now for the difficult part....
Getting it Running:
Firstly, the use of a timing light is essential to determine which pair of coils are firing and when.
Maps for Fuel, ignition and basic settings are required, these are shown below. Remember these are for a 1040cc engine with an R20 cam and running 4 x 36mm throttle bodies with MegaSquirt.
The Fuel map controls the fuel at any given throttle opening and revs.
Note, the throttle opening scale is not linear because 4 x 36mm throttle bodies only need to open a fraction to supply the same amount of air as 2 x 1.25” Stroms!
The engine constants page tells Megasquirt the size of injectors and type of engine it is controlling.
When in closed loop and Autotune, the ECU will adjust the fuel to meet your target AFR Table. As can be seen below the the AFR at cruising speed can be 15:1 while at WOT it needs to be around 12.5:1 to avoid damage.
Acceleration Enrichment is quiet difficult to get right, correct fuel enrichment at High Revs Accel might be too much at Lo Revs Accel, so it is tuneable in the AE wizard
An advantage of Full engine management is 3D control of the ignition timing, which allows the timing to change with throttle position, unlike a Distributor.
There should be enough info above to at least get the engine running and maybe out onto the road, but perfecting the maps will take many miles or huge cost on a rolling road.
When mapping there are two cardinal rules:
1.If in doubt run the mixture RICH, my engine will run at anything down to 10:1 AFR
2.If in doubt retard the ignition timing.
These are important, this engine MAY develop 3 x the original power and any detonation will finish the engine off before you can say “What hole in the piston!!!”
I haven't finished optimising the mapping yet, when I have, I'll put it on a rolling road and see if the results match that of the models in the “Length of manifold Post”
Finally:
Fuel Injection has updated the engine up to modern standards, it will toodle along at 1500 revs in town all day without baulking or chugging, then pull away at Wide Open Throttle without spluttering.
Floor the throttle and it's pure race engine, snorting and rasping it's way to 8000 revs as the acoustic waves travel up and down the manifold....
You just got to hear them!
After a Rolling Road session it was clear that the 2 x 1 1/2” Stroms had very poor mixture control and were restricting peak power.
A manifold with four independent runners and Throttle Bodies would have better mixture control, increase power and improve economy.
The manifold design process has been described in a previous post.
viewtopic.php?f=4&t=716
This write up is to help anyone considering Injecting their Imp and will be kept brief by using photo's and parts description. Please study the photo's carefully for build details.
So starting at the front of the Car....
Fuel pumps are 2 x Walbro 190LPH in-tank pumps, on a “mounting pipe” as shown. The assemblies are threaded down through the filler cap and the pump “mounting pipe” brought back out through a 10mm compression fitting in the roof of the tank.
The original pump suction pipe is now the return from the fuel rail, the vent pipe continues as the vent, the “mounting pipe” can be seen between the two. There is no “swirl” pot as the tanks in the Davrian are quite deep, I haven't noticed any fuel starvation even with low fuel and hard acceleration!
The return from fuel rail to left or right tank, is selected by a 3 way LPG valve, VSV12 from BioTuning.co.uk and is mounted on the Forward Footwell bulkhead.
Engine sensors:
The crank sensor is from 1995 1.3i Ford Fiesta and mounted on the front of the Timing case. The 36 – 1 toothed wheel is from Trigger Wheels and can be seen sandwiched between the crank pulley and its mounting flange. The Distributor blank is an aluminium bar turned to the correct diameter, 50mm long with 2 O ring grooves and a threaded hole for the “strongback”.
The Wasted spark coil pack is from a 1995 Mk3 1.4 Ford Fiesta and is mounted on the side of the crankcase above the Dip stick.
The Coolant Temp sensor is mounted in the boss next to the dashboard temp sender and is a standard coolant sensor.
Air Temp sensor is a standard “white” sensor and is glued into the lower plate of the air filter.
The Throttle position sensor was included with the throttle bodies from a 2002 Triumph 600cc Speed Four.
Injectors are from the above throttle bodies as is the Fuel pressure regulating Valve
The plastic fuel rail from the Triumph was not used as the Imp's exhaust is directly under the inlet manifold, instead a Stainless fuel rail from an Audi A4 2.0 petrol was shortened to fit.
A wideband Lambda sensor is essential, it would be almost impossible to tune the injection system with a narrowband sensor and would be difficult to use the Megasquirt Autotune facility and Closed Loop System, an Innovate LC-1 wideband AFR sensor is used and connects directly to the Megasquirt ECU.
All the components are assembled as per photos....now for the difficult part....
Getting it Running:
Firstly, the use of a timing light is essential to determine which pair of coils are firing and when.
Maps for Fuel, ignition and basic settings are required, these are shown below. Remember these are for a 1040cc engine with an R20 cam and running 4 x 36mm throttle bodies with MegaSquirt.
The Fuel map controls the fuel at any given throttle opening and revs.
Note, the throttle opening scale is not linear because 4 x 36mm throttle bodies only need to open a fraction to supply the same amount of air as 2 x 1.25” Stroms!
The engine constants page tells Megasquirt the size of injectors and type of engine it is controlling.
When in closed loop and Autotune, the ECU will adjust the fuel to meet your target AFR Table. As can be seen below the the AFR at cruising speed can be 15:1 while at WOT it needs to be around 12.5:1 to avoid damage.
Acceleration Enrichment is quiet difficult to get right, correct fuel enrichment at High Revs Accel might be too much at Lo Revs Accel, so it is tuneable in the AE wizard
An advantage of Full engine management is 3D control of the ignition timing, which allows the timing to change with throttle position, unlike a Distributor.
There should be enough info above to at least get the engine running and maybe out onto the road, but perfecting the maps will take many miles or huge cost on a rolling road.
When mapping there are two cardinal rules:
1.If in doubt run the mixture RICH, my engine will run at anything down to 10:1 AFR
2.If in doubt retard the ignition timing.
These are important, this engine MAY develop 3 x the original power and any detonation will finish the engine off before you can say “What hole in the piston!!!”
I haven't finished optimising the mapping yet, when I have, I'll put it on a rolling road and see if the results match that of the models in the “Length of manifold Post”
Finally:
Fuel Injection has updated the engine up to modern standards, it will toodle along at 1500 revs in town all day without baulking or chugging, then pull away at Wide Open Throttle without spluttering.
Floor the throttle and it's pure race engine, snorting and rasping it's way to 8000 revs as the acoustic waves travel up and down the manifold....
You just got to hear them!