i was told a primary s5 fuel rail will not fit on an s4 turbo II engine because the clearance with the upper intake manafold.

i wish to use s5 pulsation dampener on my system instead of s4 which are known to have a higher fail rating then the s5 units.

 

I would stick with an S4 unit, the S5 are just as likely to fail as the S4 and it's an even more pain to fix, ask me how I know....

Plus, with the S4 you can easily buy the new PD while being able to keep the fuel rail, whereas the S5 will end up with a new fuel rail+PD. I wish my S5 had a replaceable PD.

Use the S4 with a new PD and you will be fine.

 

^ +1

The PD itself is basically the same thing between S4 & S5, so with the S5 rails you're just forced the replace the whole thing when it leaks.

And an S5 TII primary rail should be interchangeable with an S4 TII primary. The secondary rails definitely don't swap due to mounting differences, but I don't think the S4 TII UIM sits any lower than the S5 version.

 

only reason i have an s5 fuel rail is because its the only one i could find locally. i dont really have a choice to the matter. if the s5 fuel rail doesnt work then i have to find an s4 and pay for it and wait for it to be shipped to me. but its much easier to try to use the s5 since i already bought it from a friend locally.

 

if you have never tried it i wouldnt nessasaraly beniffit from your reply now would i.


for some reason i have a huge gap between the injectors causing the fuel rail to not seal the injectors

 

As far as the gap, did you remember to use the plastic spacer that fits between the engine block and the fuel rail? the two bolts go through it and it spaces the rail out a bit.

Then there are the grommets the fit on the injectors themselves, one on the bottom, and a o-ring on the top.

 

Are your primaries the stock mazda injectors for the TII's/ or aftermarket?

Do you have the spacer that goes between the fuel rail and the motor?

 

It's a matter of common sense. There's no difference in S4 & S5 injector size, there's no difference in UIM clearance & no difference in the mount point on the center iron. As pointed out already, any gap created in your installation is going to be due to user error (ie leaving out the plastic spacer, proper rubber grommets, etc...). I've done a lot of mixing S4 and S5 parts, including NA primary fuel rails, so I've got a little background in the subject.

 

turns out the plastic "basket" defusers were left off when my primary rail was installed leavingg 1/4 inch of a gap. what was also left out was the plastic spacer. because of this there was no gap and i could run the s4 fuel rail with out the deffuser baskets. switching to s5 fuel rail, a spacer is not used for the fuel rail and thus i now have a 1/4 gap cuz i have no basket.

2ndary fuel rail has baskets, so im not quite sure at what point the error was made. it could have been from previous owner of the engine prior to rebuild. but the problem was identified.


also noted, the "oil injectors" block the injector clips, its a really tight fit in there and the injector clip touches the "oil injector" but i have worked around the issue.

part number for basket missing is n236-13-260a and they are about 47 bux each.


im currently looking for these primary baskets for the s4 tii. if any one has any.

 

S5s are still supposed to have the plastic spacer. It is possible to bend the S5 primary rail's bracket if someone were to crank it down without the spacer, so you might need to bend it back. The "baskets" are also 2 pieces: diffuser and air bleed, so make sure you find both to get the right height. S5 lower grommets are also a different PN than the S4 versions, but from experience the S4 ones worked just fine when I used an S5 NA rail on my S4 block. There's apparently no difference in grommet thickness. There are pictures of everything on the mazdatrix site here: http://www.mazdatrix.com/c-6.htm for reference.