top-feed vs. side-feed

[got_boost702]

what is the benefit of top feed over side feed if any?

[VitaminT]

They are cheaper....but you have to buy a new fuel rail.

[Onizuka]

top feed vs sidefeedprice vs ease of install

[got_boost702]

so is there any performance benefits and if i do go with top feed is there any problems that can be expected?

[VitaminT]

There might be a larger selection of volumes that can be had with top mount. Also make sure you are ready to splice your wiring harness to install them. You need to make sure the top feed fuel rail that you buy it made for the injectors you get. Some topfeeds are larger or smaller on the inlet side. Like J-spec said it is a matter or ease. Sure it might be a few bucks cheaper, but you have to solder the new injector pigtails/clips to your wiring harness, move your FPR and other lines to the new rail. Adjust the mounting brackets to fit, make sure you rail is made for your injectors..............all that vs. droping plug and play side feeds in.

Top mount it a great way to go and if you can do it for less and don't mind the hassle then that is great.

[unfrgivn]

There are NO advantages to side-feed other than it being the lazy man's way out. Top feed are cheaper (even after buying a new rail) and much easier to find if you need to replace. They're both just as easy to install. If you go with 50lbs MSD injectors, you can very cheaply upgrade to 75 pounders in the future, as opposed to dropping another $500-600 on 750cc over 550cc side-feeds.

And you have to cut up your harness with side-feeds unless you get NISMO/Tomei injectors. Power Enterprises, Apex'i, Denso all use didferent plugs. So you have to chop off your harness plugs and put new ones on.

[Movingviolation240]

Side feed is more reliable, the fuel flowing around the injector helps cool it. They last longer and operate better at higher stress levels. That's the whole reason they came up with the side feed design in the first place (cooling).

That said the side feed rail will not move quite as much volume of gas as a top feed (due to the hole the gas has to flow through being smaller than most aftermarket rails). It's generally accepted that 740cc is about as big as you want to go on the stock rail. The next step from there is the Border rail and 850cc injectors.

Paul

[unfrgivn]

Side feed is more reliable, the fuel flowing around the injector helps cool it. They last longer and operate better at higher stress levels. That's the whole reason they came up with the side feed design in the first place (cooling).

Paul

Really? I never thought about that. It makes sense though so thanks for the correction.

I still think if you're trying to save some money top feed are a better solution. I would have saved over $100 by going with a top feed rail and MSDs, but I'm also lazy.

[Movingviolation240]

Nothing wrong with Lazy people, we will inherit the earth after the other's work themselvs to death

[f150intally]

I'm currently researching this topic as well. Top feeds aren't quite as easy to run if you are running the stock ECU. If you buy the larger top feeds they are low impedance only. That means you will need a resistor box to change the impedance, which also adds to the cost ($25). So with the top feeds you will have to 1) buy a new fuel rail, 2) cut your engine harness, 3) add some wiring to splice in a resistor box, 4) buy a honda resistor box to change the impedance from lo to high. I've added up some prices for the install:

Top FeedInjectors 72lb MSD - $250ishHeavy Throttle Fuel Rail - 150Resistor Box - $30Wire - $10

Drop-in Side FeedInjectors - $480-540

Main difference is that no wiring changes or splicing has to occur for the side feed injectors. Some people think there is value in not having to "cut up" you wiring harness.

[msaskin]

[quote=" f150intally Main difference is that no wiring changes or splicing has to occur for the side feed injectors. Some people think there is value in not having to "cut up" you wiring harness. [/quote]

For most side feeds you'll have to cut up your harness. We installed Power Enterprise 550's on unfrgivn's car and the injector clips are different, so we had to cut off his stock injector clips and wire the new ones in.

~matt

[f150intally]

yeah, i realize that. I was talking mainly about the NISMO/Tomei setup.

BTW, is it easy to do?

[msaskin]

yeah, i realize that. I was talking mainly about the NISMO/Tomei setup.

BTW, is it easy to do?

Putting new clips on? Yeah, real easy. Less than a few minutes per injector. All you're really doing is cutting the old clips off, stripping the ends of each wire, crimping on a little connector, then sliding it into the new clip.

~matt