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Thread: Headstud comparison

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2008-03-21 22:44:15
Headstud comparison
I got bored and took some pics to compar the ARP head studs for the sr20de(t) to the Greddy headstuds to the ARP 1/2 inch headstuds.

As you can see the Greddys are long since they do bottom out in the block unlike the arps for the stock block. The bolts on the Greddy's are huge so are the washers. I didn't take a pic of the arps for the stock block to comepar bolts bc the are still in the bag and need to sell them. I can take more pics and questions if needed.

2008-03-21 23:10:23
matt... do you have a block that is tapped for the 1/2 inch yet? if so can you take a picture of the tapped hole for me.
2008-03-21 23:27:01
The other day right after the markam meet we ran into a little problem with andre's 240 on I-75. apperently the boost went through the roof, and we popped the head gasket. not a big deal, but when we removed the head we discovered that it wasnt the head gasket(stock with o-rings), but that it pulled the arp's right out of the block which inturn left no threads in the block. well we gave AMS a call and asked them about this happening and they confirmed the same thing at high boost levels. so they talked about how they installed 11mm head studs and the same thing happened. so to fix the problem, they installed an insert into the block called a TIME-SERT. after that the KA has had no more of the stud pulling issue witht the 11mm at very high boost and is holdiong together fine. well we ordered the time-sert's and installed them last night. what a great repair, at the same time increasing the holding capacity of the stud's threads. after drilling out the stock hole to the correct size and threading it, we then installed a stainless steel insert that covers the whole lenght of the hole. so know the stud can grip a stainless steel insert and then the insert grips the block in turn increasing the surface area that is responsible for anchoring the head. the reason that i asked you about taking pictures of the hole is becuase i want to install 1/2 inch head studs with the time-sert's.

here is the link to the web site.

2008-03-22 00:02:34
Sorry if this is a stupid question but isn't that the problem with ARPs head studs? They put extra strain on the threads due to the design flaw. Not bottoming out and being designed for iron blocks and what not. If it is a high boost car why use the sub par studs at all?
2008-03-22 00:28:32
well the problem with the current 11mm sr20 stud offered from arp is that they dont "bottom out" in the block. they stop short because they run out of threads and the stud is only anchored in by the few threads that have experienced lets say "interference" caused by the stud running out of threads. you see the treaded portion of the arp stud is smaller in diameter than the shank of the stud. so since the stud does not bottom out and the shank being larger than the hole... this is where it gives the false impression that everything is o.k.

the aebs stud is hard to find if at all.
the tomei and the greddy studs are extrememly expensive.

so me installing off the shelf 1/2 inch arp head studs is looking to be the best option right now. and with the installation of the time-sert option... will be what i think is a flawless design to the head stud issue.
2008-03-22 00:34:45

here in matts picture. the shortest stud you see is the current arp stud offered for the
SR20. you see how short the lenght of threads there is when compared to the greddy and 1/2 arp? also do you notice the small expanded piece of material that is on top of the threads? that is what gives the false impression that the stud has bottemed out. also is what causes the interference and leaves only the threads that have been affected by the interference to be the anchor for the head. on the greddy studs.. the shank of the bolt is thinner than the threads. this is good because it allows the stud to be installed the total lenght of the hole to take advantage of the extra material to act as the anchor for the head. the 1/2 inch studs.. the shank is larger in diameter than the threaded portion... but it makes up for this flaw by the threaded portion's, extra lenght.
2008-03-22 01:06:52
I will get a picture of the block but I like that TIME-SERT thing. I know the arps I am using are 12mm and Mazworx as not seen an issue with the head lifting as they did with Andre's car.

So what is this talk with going with needing big head studs. I have a block at the house for you with everything you need to make big power.....remember you built it.

2008-03-22 01:21:39
it will be a det this time. and it never hurts to have a back up plan.
2008-03-22 02:35:31
Lance -

I noticed you hadn't mentioned anything about the Cosworth head studs...

Do you not recommend them?
2008-03-22 03:08:33
yes. sorry i forgot to mention them. the cosworth are a perfect design also. i little pricey but well worth it.
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