In an effort to more understand engine tuning I’ve been doing some reading online and what not and I came across sequential vs batch injection. From what I’ve read batch injection is far more simplified and seems to make the same amount of power and be a better system for high performance applications… The downside to batch injection seems to be emissions on partial throttle. My question is how high performance is batch injection meant for? Is it used on street cars or is it used at all anymore?
Most anything these days is sequential and that is the better method since batch firing injectors means you are firing some cylinders when the intake valves are still closed. Google it and you will find a lot of info, there are some awesome books out there as well.
:number1 I just ordered a book about it today. I understand firing when the valves are closed but it is still thought to be favorable in high performance apps because the time to fire off an injector decreases as the rpms start to climb. I also found that sequential systems that are used with a performance cam that has 220° of intake duration with. 050 valve lift can only inject ~ 60% of the fuel that a identical batch system can. Which basically means you need to run bigger injectors with a sequential setup in order to get the best fuel delivery.
Are we talking aftermarket EFI or OEM efi systems? For WOT power I don’t believe sequential to have any benefits other than maybe individual cylinder control.
Aftermarket
From my understanding and I could be wrong, that generally as dsb said most everything now a days is sequential, but when under WOT as far as I know generally revert to batch firing.
They actually switch between sequential and batch? That seems odd :rofl
My car is batch and it’s hard to lean it out at idle, It’s only a straight 6, with 780cc injectors. I’d like to convert to sequential for next year to hopefully smooth out the idle.
To drastically over simplify things the differences between batch and sequential fire are only apparent at lower RPMs. On a domestic V8 past roughly 3500 RPM your spinning the motor so fast that injectors fired sequentially are firring just about the same as batch fire. Most batch fire OEM stuff went away after the very early 90s because sequential offers much better part throttle drivablitiy and thats where 99% of a street vehicles usage is. I’m spending the extra cash to run the accel DFI setup I have as a sequential, but the cost vs. advantage is going to be different depending on what system your running. Also there has been some debate that the fuel being injected onto the back of the closed valve is actually not a bad thing and can help with difusing it into the intake charge. Basically there are some novel long threads on different forums written by people who know way more then me.
My .02 cent is if it’s a street car and you can afford to set it up sequentially then do it you’ll be happy in the long run.
Yea I could have rambled on but there are tons of writeups online and lots of good books. I almost had my friend get the Accel DFI for his '90 Camaro but I’m going to have him run an EBL instead I think. The difference you mentioned is why I was saying power wise there is not a difference, but some do claim the fuel being injected while the valve is closed has positive effects.
I like the oem sequential in my Mustang a lot, for an older computer it will do quite a bit. I like the ability to adjust injector timing at different loads and like you said it provides a better idle and cruise. I don’t think it is a huge issue when stock but once you add some mods the sequential is nice.
IDK if its a full on switch to batch firining or more like what tomanycamaros said, that when the RPMS get past a certain point its so fast that the injectors are basically firing at the same time…