Side Feed vs. Top Feed
 

Hey folks,

I'm looking to install my Haltech E8 soon. I'm currently running 440cc stock injectors and stock fuel pump on a CT-20B ball bearing turbo. I know that a lot of 3S-GTE owners out there are capable of running up to 275rwhp on stock fuel and internals while maintaining a safe duty cycle on the fuel system. Anything beyond 275rwhp is just maxing out the stock fuel system with risk of blowing the motor.

I do plan on, however, upgrading in the future to 550cc injectors and a bored out fuel rail to support this along with a Walbro pump to support bigger power. I'd like to know what the difference is and pros and cons between a top feed fuel rail/injectors versus a side feed fuel rail/injectors?

Reason is because if I'm aiming for more power, I want to be able to maximize the power available over what I can get from a factory/stock fuel system while maintaining a well balanced gain:cost ratio. I'm not trying to be cheap - I just want to get the most out of my car without making things too complicated and costly.

Thanks! :)

My friend has the wolfcatz sidefeed rail with 550's and he says it was overpriced. Now that he's done he says he should have went with a top feed. Were going to have to upgrade the injectors pretty soon though as his are already near max.

Berz out.

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On the 3S-GTE?! Yes, it's expensive. I was just looking at their site. I know that KO Racing and ATS can bore out the stock fuel rail allowing you to install the Supra 550cc injectors. Anything above and beyond that requires the SARD drop-in 850cc injectors or a top feed system.

How much power is he pulling right now and at what duty cycle is his fuel system running at?

Not sure on the pros and cons performance wise but top feed gives you a lot more size/manufacturer options for a lot less money.

As others have stated top feeds are cheaper and easier to get. They are in general easier to change and are less prone to leaking.

The only advantage to side feeds is that they have a low install height which makes them ideal for applications where they have to sit under a long runner intake manifold.

Side feeding allows for higher flow ratings, less clogging (as the fuel feeds all around the injector instead of just one entrance), and allows for a positive side-effects that cools the injector as the fuel feeds through it.

Have you looked at dual-feed systems?

curious what turbo you plan on upgrading to. A friend of mine just dropped in a td06 and a tmic and it hauls ass.

I'm going to stick with the CT-20B I already have in there. Thought about getting a GT28RS but figured with the amount of money required to be invested, the gains would great but I'd rather harness the potentials of the CT-20B for what it's worth. Besides, the current exchange rate really puts me off on buying a new turbo kit.

I'm more concerned overall about what a particular turbo can do alongside with my existing list of mods and a proper standalone dyno tune. I don't want to turn my car into a dyno queen - I just want it to run efficiently and to be able to get the most horsepower and torque available given the circumstances and its state.

That's good info. Thanks!

No, I haven't looked into dual-feed systems. I think for now, I'll just stick with the stock side feed system until I plan on any power goals beyond 300rwhp.

There are other constraints than just picking top / side.. the size / geometry of the intake manifold etc.. have to be taken account, since ideally you want the fuel to be atomized as fine and evenly as possible with the maximum amount of air.

Just pissing as much fuel as possible, might be trying to kill an ant with an atom bomb.. so FEA and some CFD will come up with a clear solution.

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Interesting. Did not know this. Thanks! :)

I think you should check/ quantify the plummage of the injectors you want.. then decide on the intake manifold (or more specifically the angle and distance from the head you want to set your injectors).. you really don't want the injectors to be too powerful so they spray to the walls for example. I would say if you want to do as much fuel as possible, you are limited to designing a custom intake manifold.

The variables are all measurable. You just need a bit of forethought to put everything together.

Yes dual injectors setup increases complexity.. yet it will be easier to manage the optimal fuel dispersion.