Engine Build
10-07-2011, 02:43 PM
#1
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Engine Build
Hey guys, So I just picked up a 5.0/302 V8 out of an 1988 F-150 to rebuild. I was curious about fuel injection systems.
Which is better MFI or SFI? I have heard SFI.
And is it possible to build an older engine like this with SFI?
Would it require a different ECM or is it something that would just not be worth the time to do?
Which is better MFI or SFI? I have heard SFI.
And is it possible to build an older engine like this with SFI?
Would it require a different ECM or is it something that would just not be worth the time to do?
10-07-2011, 09:58 PM
#3
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Ford must think SFI is better as that is what they evolved too.
Bank Firing Injectors
� Bank fire means that the injectors are divided into 2 groups. On V8 engines cylinders 1 4 5 and 8 open together and cylinders 2 3 6 and 7 open together. This creates an equal distribution of fuel atomization inside the intake manifold.
� This usually works just fine on engines, in fact you can buy an after market programmable fuel injection management systems that is bank fire and can support 1000+ horsepower engines.
� Bank Fire program is not dependant to the firing order of the engine. The injectors do not match the spark order of an the engine equal distribution of fuel atomization inside the intake manifold still exists Idle quality and fuel economy can not be as greatly tuned as Sequential can.
Sequential Firing Injectors
� Sequential fire means one injector is fire a while the intake valve is open. This creates an equal distribution of fuel atomization inside the one intake manifold runner during the intake stroke of that cylinder..
� The programmed time of when to open a injector is matched to the camshaft grind profile. People get into trouble here because camshaft swaps that do not match the program can affect low RPM stability of the engine.
� Sequential Fire program is also matched to the firing order of the engine. If the injector order does not match the spark order of an engine low RPM stability of the engine will be lost. High RPM will still create an equal distribution of fuel atomization inside the intake manifold. But idle will suffer poorly.
� Sequential Fire program gives greater ability to program better idle quality and fuel economy, but it must be all matched in the program for these gains. There is NO performance gains to be had from sequential firing injectors.
Bank Firing Injectors
� Bank fire means that the injectors are divided into 2 groups. On V8 engines cylinders 1 4 5 and 8 open together and cylinders 2 3 6 and 7 open together. This creates an equal distribution of fuel atomization inside the intake manifold.
� This usually works just fine on engines, in fact you can buy an after market programmable fuel injection management systems that is bank fire and can support 1000+ horsepower engines.
� Bank Fire program is not dependant to the firing order of the engine. The injectors do not match the spark order of an the engine equal distribution of fuel atomization inside the intake manifold still exists Idle quality and fuel economy can not be as greatly tuned as Sequential can.
Sequential Firing Injectors
� Sequential fire means one injector is fire a while the intake valve is open. This creates an equal distribution of fuel atomization inside the one intake manifold runner during the intake stroke of that cylinder..
� The programmed time of when to open a injector is matched to the camshaft grind profile. People get into trouble here because camshaft swaps that do not match the program can affect low RPM stability of the engine.
� Sequential Fire program is also matched to the firing order of the engine. If the injector order does not match the spark order of an engine low RPM stability of the engine will be lost. High RPM will still create an equal distribution of fuel atomization inside the intake manifold. But idle will suffer poorly.
� Sequential Fire program gives greater ability to program better idle quality and fuel economy, but it must be all matched in the program for these gains. There is NO performance gains to be had from sequential firing injectors.
Last edited by 73Fomo; 10-07-2011 at 10:22 PM.
10-08-2011, 02:12 PM
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You're stuck with a speed density computer and buying a TwEECer if you plan on doing any serious modding(which you can easily turn into SEFI with the TwEECer), or buying a SEFI/MAF computer anyway. Speed density trucks wont run with engine work.