Ok guys (and gals) I need fuel rail help. We now have 3 aftermarket fuel rail options that I know of; MRT, Vishnu, and Perrin. I have read as much as possible on these systems and they are somewhat vague and inconsistant. They all say that at hight boost and horsepower levels that to factory fuel rail design allows certain cylinders to go lean. What boost and horsepower levels are they talking about? I haven't seen any real numbers from any of these kits. If we're talking 400 horsepower than I'm not worried but if it's at 300 horsepower maybe I need them. MRT says the number 2 cylinder goes lean but Perrin says number 3 cylinder goes lean. What's up with that??? Vishnu's fuel rail section (on their website) doesn't mention any specific cylinder going lean and only mentions that the factory injectors/fuel system are taxed at the 300 horsepower level.

I'm planning on running a VF-30, STI injectors, Walbro high pressure 255L fuel pump along with my ECUTEK. Should I invest in fuel rails with this level of mods? What about the fuel lines with these kits. Perrin comes with stainless lines. Vishnu, I'm assuming are rubber lines with a stainless line option and MRT are rubber lines. Which would work the best? I would think the rubber lines would allow the fuel to remain cooler since the rubber doesn't conduct heat, but the stainless would be safer and last longer.


Has anyone had experience installing any of these kits? If so did you run into any issues? Can the stock fuel rails be removed from the engine without pulling the intake manifold off? Maybe some of these vendors could chime in on this thread.

Thanks,

Punk

 

Punks - Yes, you can remove the stock fuel rails and all the stock fuel pipe without removing the intake manifold, but it's a huge pain. The fuel pipes are bolted to the underside of the manifold. You have to cut/hack the pipes apart to get it all out in sections.

Honestly, you'll spend less time removing the stock fuel pipes/rails if you remove the manifold. Plus, you'll have the added bonus of having your oem fuel system in one piece, in case you ever decide to put it back in.

If you're using STi injectors, then it's probably better to get the Perrin rails, as they allow the injectors to be positioned properly. The Vishnu rails won't allow the injectors to be positioned as they are stock.

 

Your oem injectors and STi injectors have a specific spray pattern (sort of a figure 8, IIRC). They won't work as well if turned 90 degrees.

My RC Engineering 550cc low impedance injectors do not have a specific spray pattern - they can be positioned any way necessary.

 

The Vishnu rails are an old design that needs to be updated. These rails where made for the older GC8 cars. Facts are facts. The Denso injectors have a split spray pattern and need to be rotated with the connectors off to the sides like a stock car. There is information on PE's website that shows the spray pattern of the Purple Injectors I sold you for your car. All of the denso injectors for this application have this split pattern. The Vishnu rails will not allow you to rotate the injectors and they will not clear the AVCS heads. I have the vishnu rails on my car and we test fit them on the JDM motor swap on a friends car.

With the injectors in sideways with the vishnu rails the spray patter splits the wrong direction and sprays right on the TGV splitter. If you where to get the Type RA TGV housings you might be ok because they do not have the splitter. Otherwise you will need to go with the Perrin rails or the MRT's. Both allow you to turn the injector and both clear the AVCS heads.

I am going to swap my vishnu rails out to the Perrins because of this issue. The day I installed the Vishnu rails my car has had a low RPM stumble because of this. I tap the gas, Fuel is injected and drips off the splitter and walls. I get a lean condition as noted on the wideband.. then the fuel drips down and the car goes rich for a second. No amount of tuning fixes this. Also, Cold start is not very smooth until the TGV's open because fuel is sprayed right on the plate instead of down the side port. I am sure fuel just puddles up on those plates.

Nick, Since you have the PE injectors I advise you to get the Perrin or MRT rails. A while back I talked with Shiv about this and he has responded to some posts about this as well. Do some searching. I agree then Vishnu tends to research things and they sell quality parts but they need to redesign these rails. Shiv has dodged the issue many times but facts are facts. The injectors spray at two side patters to clear the TGV splitter and to insure a direct shot into the ports. If you look at the tip of the injectors you can see the pattern. If you hold a TGV housing in your hand and insert an injector you will see how the fuel will spay at the splitter...

my .2cents..

CT

 

Thanks guys. Great info here. I went ahead and picked up the Perrin rails. So, are the STI or stock fuel injectors marked or keyed to fit in the injector bore only one way? I want to make sure I install them in the correct orientation. Do the STI cars have TGV's? If not could the STI injector have a different spray pattern that the stock injectors?

thanks,

Punk

 

Just install the injectors in the same orientation as the stockers. The connectors face out from the motor on the front and face back toward the firewall on the rear sets.

STI cars have no TGV plates or motors. They do have the Splitters. If you are going to change them I would get the STI Type RA TGV housings. They do not have the plates and they do not have the Splitters. They are just straight through. Cost is about $150 or so a pair.

CT

 

Thanks azscoobie. I don't have a shop manual. Would you happen to know the tightening sequence and torque specs for the intake?

Punk

 

I dont off hand man.. Sorry.

CT