injectors

[canadians14]

HI i am debating whether or not to change to top feed injectors on my KA24DET. I was either going to use MSD 50lb/hr top feeds or side feed's of the same size. I know Nissan changed from top feed to side feed in 91... why? Side feeds are more expensive as well... so i know that they didnt change to reduce costs. Does anyone know the reason for the change?

[andrave]

OK, first off, what is more expensive for you and I isn't always more expensive for companies like nissan... first consider that most of the side feeds are made in japan, so they are cheaper in japan. Then consider that nissan doubled up on its injectors sizes (ie, the 370's fit vg30dett, sr20det, etc) so they were buying them in orders of hundreds of thousands per.Anyway, having said that, supposed side feeds allow you to run a higher duty cycle per injector size... I also read someone say that the fuel flows around them as a coolant of sorts, keeping them cooler and therefore increasing their duty cycle. Also I've read that high impedance injectors are "easier" to control somehow than top feeds, especially at high duty cycles.Anyway, I can't answer that question definitively, and I doubt anyone but the engineers that worked on that engine could either. It is true that sidefeeds are more prone to leaking than top feeds, too...ultimately its a decision of economics. You gotta buy/make/ghetto up a fuel rail for top feeds, but they are usually substantially cheaper than side feeds...

[C-Kwik]

There could be several reasons. I can only speculate, but sidefeeds are cooled by the fuel that runs through it. I'd say that's the most significant difference and likely a reason for the change.

[canadians14]

thanks for clearing that up ... i think i'll go with the top feeds... they make better sense for me plus i won't have to pay the extra money for JWT to retune for side mounts. Living in Alberta Canada makes it pretty difficult to get down to a dyno for a little fine tuning.