108 replies to this topic

[mini_me]

On a test engine (well its really my mates engine im building for him) im having a go at using an injector as a second means of fuel at higher boost 10psi, plus the use of an intercooler and water-methanol (denatured alcohol) injection to suppress the chance of detonation. With a cr of about 10.4:1, because of the spool up time of the t3 it will help with lower rpm torque. I was unsure whether to place the water injection before the turbo as a very fine mist so to reduce wear on the fins, or directly into the inlet manifold with the fuel injector? Also what would be the best way of rigging the injector? was thinking of useing the boost bleed solenoid already found on the metro turbo? Would be grateful of any ideas or opinions.


Cheers! :grin:

[MRA]

Hi,

Are you using an ECU ?

If its a fuel injector ? it will need better control than that ! How do you propose to control the amount of fuel going into the engine ??

Good luck

[mini_me]

Im not using an ecu, was hoping to find an injector wih a low flow rate and a good spary pattern, something like the spi on an astra. It only has to come in when it detects the higher boost pressure. I no its more complex than that as it requires the correct impedence to run an injector but im sure there's a way round it.

Cheers :grin:

[Wiggy]

How are you going to control exactly how much fuel the injector squirts?

[mini_me]

Like i said will have problems getting the impedence correct. Was also thinking of using;

T piece from existing fuel line, boost sensing solenoid to allow fuel through to a fuel pressure regulator (set to a low psi) runing to a carb jet? But im still sure i can use an injector??

Any other ideas would be much appreciated!!!

Cheers! :grin:

[AlexF2003]

wear on the fins?!


Alex

[mini_me]

Yeah, if the water-methenol mixture isn't a fine enough mist it'll be like sand-blasting the fins, large water particles under only 10psi hitting an object spinning at only 35000 rpm will relativley quickly cause a fair bit of damage! Especially when most pumps that suit this job put out 45psi plus methanol is quite a corrosive substance.

[Turbo Nick]

what benefit is an injector going to give over the HIF44? i run 15psi and have no problems with lack of fuel, people running 20+psi have no problems either? seems pointless in my opinion.

[Sprocket]

:erm: Turbo with a CR of 10.4:1

[DaveCoxon]

This has bad-news written all over it...

Sorry to say, but BAD NEWS!

If you want to run a single injector, you need an injector driver, like the MF2.
But - running this is plain silly on an A-series, as if you set it to (say) 25% duty cycle, the cylinders that want the fuel for the other 75% will be left to run lean the next time they take in an induction charge as the injector is off.
If you want to do something novel, use a butcherized Bosch k-jet system, with just one, or maybe two injectors in the inlet tract (not manifold, but TRACT) - you can adjust the k-jet stuff quite easilly - ie MAP IT, and mechanical injection in the inlet tract (before the butterfly) will work not too dissimilarly to an SPi injector...

[Turbo Nick]

i read it as he wanted to use an injector aswell as the carb.....

[Wil_h]

I agree with Bud. Why would you need an extra injector? the carb should be more than capable of supplying you with enough fuel.

The most important thing you'll need is mapped ignition so you can retard the ignition enough to get 10psi with a CR of 10.4:1. Pointless really. If you want a quicker spool-up, spend the money on a turbo better suited to the engine.

Wil

[eddyg]

Yea on this front who runs a turbo mpi engine round here?? cause when i do mine i want to get a well nice ecu because then the controlability you can get for tuning the engine is enormous. You can have diffeent setting depending on what you are doing...i.e set it to run off boost for long trips, lean mixture and low rev limiter for MOT and just all out chaos for the 1/4 strip. But just wondering who runs an injected turbo mini??

[DaveCoxon]

I will be returning to injection in 2006 - now i've found some suitable injectors, and learnt a lot more than i used to having tried Weber Alpha and DTA previously.

It's not something to blindly jump into - injecting an A-series is difficult. Injecting a 200+ (hopefully :cheese: ) hp turbo is very challenging; as is a 8000+ rpm screamer aswell due to the limited injection window.
One simple piece of advice - if anyone says it's 'easy' to do, then they haven't tried it.

[Sprocket]

Turbo charging the MPI would be the simpler ( not easy in relation to carb)of the injecton systems as you can use the original inlet swap out the throttle body for a turbo ( sealed unit, if there is actualy any difference other than it being alloy) off another Rover (almost like for like), pipe the discharge of the compressor through an RS intercooler going direct onto the throttle body. The MPI already has two injectors with others freely available in a veriety of cc/min to match the power, all the temp sensors are there, already has an oxygen sensor, all the wiring and relays are there and the direct fire distributorless ignition coil.

I personaly would use the Megasquirt engine management system as it is freely adaptable to almost every situation. Only one problem I see is the crank position sensor, I don't know if any one has coded the Megasquirt for Rovers unique pick up pattern. It would also be easy to fit a knock sensor. This along with the usual turbo required mods of course.

Big boost high power engines would require very big injectors in relation, causing difficulty in a single or twin injector system to control the low rpm fueling, so medium power increases would be much more succesful

cant see why it cant be done, but it certainly would not be as simple a carb turbo.

Realy got to get this sussed for my project, though I will be using four injectors with a single throttle, similar to below but not the same

EDIT: picture changed

Edited by Mini Sprocket, 14 December 2005 - 06:25 PM.