Injector Flow Rate?
Discussion
Around 200cc/min. (Some say 180, some say 220) Whatever they are, the flow matching between them can be up to 20% different (from logged data and calculations from my VEMS project - so lots of error margin on the measurements!!)
It's pretty cheap to import good injectors from the USA - I got a set of 8 1% flow matched Siemens 600cc/min for <£250.
It's pretty cheap to import good injectors from the USA - I got a set of 8 1% flow matched Siemens 600cc/min for <£250.
brummiewedge said:
Can anybody actually answer the question!? would post icon but dont know how!
I don't know if all the 4.0 injectors are the same spec, although I think they probably are. Mine were D1830GA 0951 green band, which I think are equivalent to Bosch 0280 150 561 and are rated at 230 cc/min or 22 lbs/hr at 40 psi. Haven't seem the GEMS or Thor ones so I can't help with them.
My 390SE has 73178A injectors on it - and they are not flowing enough as I go down to an AFR of 15:1 at 4500 rpm (2.55 bar pressure maintained). By my calculations I _should_ have 210cc/min injectors installed to achieve the 260 TVRBHP claims. - I'd need around 3.6 Bar with 180cc injectors which sounds dangerous. Are these the standerd 350i injectors I have or something uprated?
Standard spec is 185cc/min at 36PSI for 14CUX Lucas injectors. Bosch Thor injectors flow the same, but at 56PSI. The Bosch versions give superior atomisation, which means that more of the fuel you inject gets burnt!
Does anyone know if the later fuel rail will fit the non Thor set up?
Does anyone know if the later fuel rail will fit the non Thor set up?
Hi, I am new to Piston heads and found this old thread whilst doing a search on injector flow rates.
I am in the process of putting together an engine management system to go on a much modified Rover V8 engine which is fitted into a 1975 MGB GT based on a Megasquirt MS1 V3
The engine spec is based on a 3.9 block with 4.2 (77mm.) crank, Chevy type 5.85" rods and Keith Black Chevy 305 pistons for a capacity of 4.35L top offed with Buick 300 alloy Heads modified with 1.63" Inlets and 1.4" exhaust valves with the seat areas opened up to seat size and the throat and bowls opened up to match, the port runners have been left to size as they are the equivalent of stage 3/4 anyway and have been left as cast to ensure that fuel is kept in suspension at lower RPM's. The camshaft is a Crower 50232 with LCA of 112 and duration of 276/281
The engine is fed by an Edelbrock 500 and performer manifold at present.
I have an EFI manifold,trumpet base and plenum off a 4.0 gems engine with Lucas D1830GA injectors, and note that these only flow approx 185cc/min at 36lb fuel pressure which is I feel going to be marginal.
I have been told that I can increase flow by upping the pressure to 43.5lb but note that you shouldn't exceed this pressure or the injectors will malfunction.
Can anyone tell me how much the flow rate will be increased by upping the fuel pressure to 43.5lb and what I need to do this?
Kevin.
I am in the process of putting together an engine management system to go on a much modified Rover V8 engine which is fitted into a 1975 MGB GT based on a Megasquirt MS1 V3
The engine spec is based on a 3.9 block with 4.2 (77mm.) crank, Chevy type 5.85" rods and Keith Black Chevy 305 pistons for a capacity of 4.35L top offed with Buick 300 alloy Heads modified with 1.63" Inlets and 1.4" exhaust valves with the seat areas opened up to seat size and the throat and bowls opened up to match, the port runners have been left to size as they are the equivalent of stage 3/4 anyway and have been left as cast to ensure that fuel is kept in suspension at lower RPM's. The camshaft is a Crower 50232 with LCA of 112 and duration of 276/281
The engine is fed by an Edelbrock 500 and performer manifold at present.
I have an EFI manifold,trumpet base and plenum off a 4.0 gems engine with Lucas D1830GA injectors, and note that these only flow approx 185cc/min at 36lb fuel pressure which is I feel going to be marginal.
I have been told that I can increase flow by upping the pressure to 43.5lb but note that you shouldn't exceed this pressure or the injectors will malfunction.
Can anyone tell me how much the flow rate will be increased by upping the fuel pressure to 43.5lb and what I need to do this?
Kevin.
CastleMGBV8 said:
I have an EFI manifold,trumpet base and plenum off a 4.0 gems engine with Lucas D1830GA injectors, and note that these only flow approx 185cc/min at 36lb fuel pressure which is I feel going to be marginal.
I have been told that I can increase flow by upping the pressure to 43.5lb but note that you shouldn't exceed this pressure or the injectors will malfunction.
Can anyone tell me how much the flow rate will be increased by upping the fuel pressure to 43.5lb and what I need to do this?
What sort of BHP are you expecting, and how rich are you planning to run at the top end?I have been told that I can increase flow by upping the pressure to 43.5lb but note that you shouldn't exceed this pressure or the injectors will malfunction.
Can anyone tell me how much the flow rate will be increased by upping the fuel pressure to 43.5lb and what I need to do this?
You probably know, but as a rough guide you need about 5 cc/min to produce 1 bhp at 12.5:1 AFR. Hence from the power figures you can estimate the peak flow you're likely to need. 300 bhp corresponds to about 1500cc/minute, or about 185cc/min per injector. You would normally want to keep the injector below about 90% duty cycle so make sure the injector can flow 10% or so more than that.
If you decide to change the fuel pressure, the usual way to achieve that is to replace the original pressure regulator (in the fuel rail outlet) with an adapter, and connect an aftermarket adjustable regulator in line with the fuel hose.
The standard flow figures are at 37 psi. If you increase the pressure, the pressure increase is the square of the flow increase. So going from 37 psi to 44 psi is a ratio of 1.19. Square root of this is 1.09, so it gets you an 9% increase in flow.
If you anticipate going beyond the maximum flow of the Lucas injectors, there are plenty of Bosch injectors that are the same physical size and shape with any flow rates you want. Best to get the injectors no bigger than necessary because if you make them substantially oversize it makes it harder to get accurate control over the fuelling at idle.
The standard Lucas injectors have propelled modified cars to 350bhp'ish by raising the fuel pressure. There are video injector flow tests / comparisons on the net that note how well Lucas & Bosch work at higher pressures.
You can tweak the fuel pressure with an adjustable regulator, in addition or place of the standard one - just make sure its a 1:1 rather than a rising rate version.
You can tweak the fuel pressure with an adjustable regulator, in addition or place of the standard one - just make sure its a 1:1 rather than a rising rate version.
Thanks guys thats helpful, I did a check on a flow to power programme and got 274BHP potential on the existing injectors at a 90% duty cycle rate at 43.5lb so should give me a comfort zone, as am anticipating in the region of 260 BHP.
One more question, if I use a 3 Bar regulator does it drop back to lower pressure say 2.5 bar at idle or cruise?
Kevin.
One more question, if I use a 3 Bar regulator does it drop back to lower pressure say 2.5 bar at idle or cruise?
Kevin.
CastleMGBV8 said:
One more question, if I use a 3 Bar regulator does it drop back to lower pressure say 2.5 bar at idle or cruise?
Normal practice is to have the fuel pressure regulator referenced to the intake manifold, so the fuel pressure is maintained at a constant (3 bar or whatever) above the manifold pressure. This means that the pressure drop across the injectors is constant which makes the fuelling calculations a bit simpler. So if you have a nominal 3bar regulator, you might see 2.5 bar under cruise conditions at barely 2 bar on the overrun.
GreenV8S said:
CastleMGBV8 said:
One more question, if I use a 3 Bar regulator does it drop back to lower pressure say 2.5 bar at idle or cruise?
Normal practice is to have the fuel pressure regulator referenced to the intake manifold, so the fuel pressure is maintained at a constant (3 bar or whatever) above the manifold pressure. This means that the pressure drop across the injectors is constant which makes the fuelling calculations a bit simpler. So if you have a nominal 3bar regulator, you might see 2.5 bar under cruise conditions at barely 2 bar on the overrun.
Thanks again,
Kevin.
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