MazdaSpeed DISI Injector Stud Kit



The OEM bolt and washer have some serious problems.

The bolt:

Torx design so its difficult to get a accurate torque reading when torquing them down.
Material appears to be of a grade 5 or lesser quality
Only threads 2/3rds of the way down into the bolt hole
Pinched cup washer makes contact with the upper portion of the threads, creating a weak section in the bolt.

The washer:

Made out of a coated A36 steel.
The profile of the washer doesn't match that of the crows foot.
To thin to support proper movement or loading from higher cly pressures (simulated testing).

What does all this mean?

The bolt will flex, creating a weak link. If it would have been made out of a better quality and longer it could have provided another 30% in rigidity and holding power.

The washer, well this is where things really get bad. The washer will not allow proper alingment of the crows foot to washer face, this missalingment only allows 1/3 (and less on others we tested) of the washer face to contact the face of the injector hold down. This reduction in face contact allows the injector hold down room to "wiggle". This wiggling effect is why you see injectors seals moving around and wearing the bottom of the injector hole or causing rings or groves where the injector seals inside the injector port. It gets even worse, the washer is very thin and made of a mild steel that flexes a great deal. Match that up to the reduction in face to face contact and you have a part that was pretty much failed from the get go.

Enter the solution.

I have taken a great deal of time and programing of the lathe in order to bring a washer, nut and stud combo that allows you to run higher cly pressures with out the worries of the OEM parts failing.

What we have to offer.

Grade 8 coated stud that we had custom ordered (min order of 500). This stud goes all the way to the bottom of the threaded hole. This will give 100% of what is available to hold the injector "tight" to the cly head.

We use a grade 5 washered nut that has been zinc coated to resist rust and matches the head of our washer "perfect".

Cup washer is made of a 1045 billet material, it has been CNC'ed with tolerances set at .001. It has been manufactured to make full contact at the face of the injector hold down thus allowing an increase over the stock assembly and holding the injector in place, not allowing any "wiggle" room. We made the .080 thicker than the OEM units and out of a much higher quality material.

Mate this up to our injector seals, and you have a solid solution for supporting any and all your power goals from stock turbo to highly modified applications.



Product Added: August 08, 2011
Part Number: hpfp00012