I'd rather be safe than sorry in the long term, so I'm leaning towards going with something other than L-19s.

 

There is still quite of bit of information that has not been discovered on the z since it is still such a new car. GTM finally broke 850rwhp after 4 years of the Z being out. We broke 800rwhp a year ago. There is a lot that every shop on here is still learning. L19s have been proven in other street car applications without issues. 1/2" have been proven for years as well.

I believe the L19 is a great upgrade for a street car or even someone that is trying to make good power that does not want to take the chance of machining the block and head for 12mm and 1/2" studs.

We have made the same horsepower (1200+) on Supras with L19s and 1/2" studs without issues.

 

what's the price difference including install between the two studs?

 

What I understand from Sam, is the L-19s are not treated to resist long term corrosion and are to be used for race applications only. Again, I want to be more safe than sorry.

 

My 1/2" studs installed at the time of my engine build was around 500-550$ i think. Thats not much considering how much it costs for the entire engine build. I chose 1/2" studs and hks gaskets because i do not want to open my engine up from headlift. You guys can love on the L19s all you want but why? The 1/2" studs are not that much and they are better.

 

For the 350Z, L19s are trouble free long term, and are perfectly fine for street use.

According to our rep @ ARP, as long as the L19 studs are kept clean and under valvecovers, they are ok.

 

Just curious...Where else would a Head stud be kept??

 

Sorry, let me explain further. As long as they are not consistently exposed to the environment (in oil, underneath valve covers, etc.) they are perfectly fine in street car applications. Hal is saying that in a more technical term

This is coming from ARP directly.

 

^^Correct^^
I am not intending to get into a larger stud vs. L19 debate, but there are pros and cons to each setup, which is the reason I would ask you engine builder/tuner for their preference. On some applications, we use 11mm L19, and others, we use 12mm or 12.7mm stud upgrades.

Just to clarify, all ferrous materials corrode. The standard ARP studs (black finish), will also corrode if left to the elements. The reason you never see the corrosion, is that fact they are sealed tightly in an engine. True, if water slips through the gasket, and into the stud, then corrosion can occur in ANY type of stud. of course, if this happens, you have much bigger issues to deal with.

 

I am a machinest and I deal with barstock a lot. Let me put that into perspective, I machine 3 tons of matel a day all of which is quite small diameter. I have quite a bit of experience with metal and the coatings they use (not chemically or electically bonded but sprayed or brushed on such as moly) and I can vouch that if you coat something right and do a one time install it will be okay.

While most might be quick to say that my barstock is more than likely different than the operations they have going on at ARP they would be half right and half wrong as we have header machines at our shop just as ARP does and uses to make things such as connecting rod bolts. The main difference I think is that they use hot headers for most things and I believe they are 3 or 5 blow where as I use 2 blow cold headers.

Overall, corrosion should be a minor concern in your decision as long as you are careful and follow the proper install procedures and cleaning process.

 

Note where I said 'stud', not 'head stud'. ARP make all kinds of studs, for example exhaust manifold studs which would not be found under the valve covers, but rather it would be exposed to the elements and there would be possible corrosion. As long as L19s are used for head studs, we are fine. Sorry for the confusion.

I agree, there is no need for a L19 vs 1/2 vs 12mm debate... to each their own. We have not seen failures from the L19s, but the amount of testing is still limited. The same could be said for 1/2" or 12mm. This is why we stock them all, and build our engines based on customer wants and needs.

 

There are many VQ's here in PR (maybe 7 or 8) that are running Std ARP's (NOT L19 NOT 1/2's) and putting down more than 650whp without any issues. Carlos Sepulveda's grey G35 gave at the dyno 749whp with NOS and 22psi and he has Std. ARP's. He has gone as far as 25psi without any issues.

https://my350z.com/forum/showthread....light=carlitos

Another Red G35 of Carlos Carrillo is putting down 650whp at 18psi with std ARPs.
I guess you could say that anything better than Std. ARP's is just a precaution.

 

We've sold a LOT of L19 sets to the PR guys too. What are they trqing the "standard" ARP's down to?

 

My STDs are holding as of now, but havnt put a lot of hard miles on the car yet. I torqued mine to 85 lbs with molylube. I talked to ARP and they said that is the max you want to torque them to. So, I guess ill just wait and see if it holds. Hopefully it will, but if it doesnt ill just upgrade to L19...no biggy.

 

Lot’s of people here have gone turbo, including myself. I can only speak of those I know, because they are personal friends, but I don’t actually know how much torque they’ve used. What I do know is that they have used std. ARP’s because L19’s weren’t available at the time of the build, and they are street driven, 1/4 mile beaten machines.

 

just to claify, which is rated for higher horsepower or torque?