In what order do you upgrade? Jon,Fen etc...
- Thread starter 333pg333
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With the vitesse maf you should let John know in advance what injectors you want to run, he may be able to offer a switchable option on the FQS switch (switch on the DME box) so you can switch between standard and you proposed injectors, or you could fit both together eliminating the issue,
Tony
Tony
Hey guys I feel like I'm back at school...not understanding everything, but I'm getting there.So are there downsides to going to 72lb instead of 55lb? Do you go for the largest possible so long as you can get the car to run smoothly in view of being able to use them for larger turbos/higher output? Does using bigger injectors increase fuel consumption? Has anyone noticed how small the tank is and how quickly the gauge goes down when your using the boost? We have to take Jerry cans of petrol out on some of our longer track days. Makes an interesting drive to the track. Important not to crash!
Also does anyone have any product suggestions such as widebands, turbos, injectors etc...it would seem the general consensus is that the Vitesse MAF kit is the one to go for.I'll be interested in what my mechanic's son is going to do with his Vitesse Stage III kit as it has a K&N filter and they don't like them. Time will tell.
Also does anyone have any product suggestions such as widebands, turbos, injectors etc...it would seem the general consensus is that the Vitesse MAF kit is the one to go for.I'll be interested in what my mechanic's son is going to do with his Vitesse Stage III kit as it has a K&N filter and they don't like them. Time will tell.
In the past (pre vitesse piggy back board) large injectors could result in a poor idle, the vitesse 'chip' (its not a chip its a plug in board that fits in the chip socket) changes the injection to semi sequential (cant go full sequential as there are only 2 injectr drive circuits in our DME's). Larger injectors allow more fuel at high boost or the same fuel as a smaller injector at a lower duty cycle. So while at 18psi of boost my 55lbs might have a 100% duty cycle and be getting hot a set of 75lbs injectors may only be at 80% and thus be operating with reserve capacity. With the 'brain' having the right info (i.e which injectors are being run) the same amount of fuel should go into the engine from each injector until the point where the smaller injector is maxed out and can provide no more.
Tony
Tony
Diver944
Active member
Does the amount of fuel delivered by an injector rise at a constant rate when the injector size increases?
For example, I believe the standard Turbo injectors are 34lb/hr so does that mean that 55lb injectors are almost a 50% increase and 72lb injectors have virtually twice the capacity?
For example, I believe the standard Turbo injectors are 34lb/hr so does that mean that 55lb injectors are almost a 50% increase and 72lb injectors have virtually twice the capacity?
not certain but I believe the figures are an amount of fuel per hour so yes probably, Fuel pressure also has an effect on fuel supplied as well though. I am not sure how much extra fuel you need per increase in boost Psi to maintain good AFR's, though this is again compensated in a limited way by the change in pressure on the fuel pressure regulator.
Lower duty cycles have more safety factor though.
Tony
Lower duty cycles have more safety factor though.
Tony
Wideband - personally I am torn between doing it cheap, tech edge (from Australia) or going for my current favourite the PLX R500 which has lots of fancy extras EGT, knock and G sensing, as well as logging and various inputs/outputs - I quite fancy linking the knock audio out into the stereo aux input. Until I have a piggyback to massage fuel settings it will just provide me with info though.
My car with vitesse MAF is running rich, at high boost, I found (with Simons help) a big leak from the Idle stabaliser valve (now bypassed) which improved things from the dyno day but I think there are still further leaks to track down. the MAF sees the air com in adds fuel to match it but some escapes leading to rich running.
Tony
Relevant to this thread http://www.motec.com/definitions.htm has some good definitions on batch , semi sequential and full sequential fuel injection also narrow band etc.
Tony
Tony
I was searching for injector batch firing in anticipation of the next question, If going standalone I would have a good look at http://www.emeraldm3d.com/em_m3dk.html having met Dave Walker a couple of times in the distant past or megasquirt which seems like an interesting option. The amount of development time needed to get the best from our engines puts me off, now if I had my own Rolling road or free access to one I would seriously consider it, especially if I had software to analyse existing chips to develop a base map,
Tony
Tony
eastendr
New member
Correct. The fuel pressure regulator pipe from the inlet manifold allows the regulator to maintain a CONSTANT pressure across the injector, no matter what the inlet manifold pressure is. Therefore the delivery rate remains linear. A 50% bigger injector provides 50% more fuel for the same injector duration regardless of manifold pressure (or vacuum).
This also explains why your car will idle rich if you have a vacuum leak to the fuel pressure regulator ...
Beware the DME. I know for a fact that some have siamised outputs (on the circuit boards - but not shown on the diagrams) therefore firing ALL injectors together instead of in pairs as some would otherwise have you believe ....
I think running rich is a symptom of Vitesse products. He likes to be safe rather than sorry. Also better for word of mouth on his products that engines aren't detonating around the world. I have one of his chips and it runs rich especially in the upper revs. The back of my car gets pretty dirty, pretty quickly. So by having the standard injectors , V chip, and 3bar fpr with it running rich does that mean that my injectors are probably maxing out to provide that amount of fuel?
Hmmm. I have a vitesse Maf, and I dont run any richer than it needs, 12.5 on boost.
And i never get the car dirty.
Any chance you are just burning oil?
If you are running 15 psi then you are ok, with the enjectors. If your running 18psi, and hve a 26/8, then you are probably right at the limit I would have thought.
Oh, and if you get the new vitesse, chip, which is actually a board, there are dip switches on it, that he selects whatever injectors you are running.
And i never get the car dirty.
Any chance you are just burning oil?
If you are running 15 psi then you are ok, with the enjectors. If your running 18psi, and hve a 26/8, then you are probably right at the limit I would have thought.
Oh, and if you get the new vitesse, chip, which is actually a board, there are dip switches on it, that he selects whatever injectors you are running.
sawood12
New member
Are you saying that the injectors are not firing independantly and timed with their own cylinders induction stroke?? I can't beleive that - you would simply have single point injection delivered with four injectors. Surely it's wasn't beyond the technology of the time to take a signal from the crank position to time each individual injector with it's own cylinder?
You can always improve the rich running of off the shelf chips by having custom mapped chips. However they are more expensive and tied to the configuration and fuel you have at the time of mapping.
Indi9xx
New member
944 turbo injection is not sequential, the ecu has no idea if a piston is on a power stroke or an intake stroke, it only knows the rough position of the crank, which will turn twice per rev of the camshaft.
Most cars until quite recently (last 5 to 10 years) have non sequential injection... Interestingly, not much increase in fuel ecconomy or power is found through sequential injection.
For modification.. I would recommend his next step to be a good chip package, then perhaps a bigger turbo with bigger injectors fitted as a package.. Then attack breathing with a modified intercooler and exhaust.
Do not be blinded by high BHP, Torque is very very important.... Massive peak BHP but without matching midrange torque makes for a laggy slow car.
Most cars until quite recently (last 5 to 10 years) have non sequential injection... Interestingly, not much increase in fuel ecconomy or power is found through sequential injection.
For modification.. I would recommend his next step to be a good chip package, then perhaps a bigger turbo with bigger injectors fitted as a package.. Then attack breathing with a modified intercooler and exhaust.
Do not be blinded by high BHP, Torque is very very important.... Massive peak BHP but without matching midrange torque makes for a laggy slow car.
Which brings me to another point. It has been implied by some that going to a larger exhaust (say 3" all the way through) can have an affect on your torque. Is this the case and if so can this only be offset by going up in turbo size? So doing exhaust b4 turbo would have a negative effect?
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