That's what I thought especially with my bad flowing '94 head. It "felt" significantly quicker than the twin's 289rwhp. Torque was only 235 though. Anyways...

Damit After running since last summer and like 6 track days I looked at my manifold and one of the nuts was gone, looked a little closer and another one was gone. I thought it was looking like I had this problem licked guess I didnt. The flange wasn’t loose yet. I replaced one of the nuts. Then started to replace the other one that is real hard to get to and as soon as it started to snug down it snapped off in the manifold. I ran sort of a really long track session a couple weeks ago. Like an hour long just coming in a few times to swap out passengers.

I have equal length mild steel manifold and was using 10mm self locking studs from McMaster 42mm long. They were rated as grade 8.8. I think they are the same thing that BEGI and ATP turbo sells.

Who has stronger studs I can get quickly? I’m heading out for more track time early next week at Laguna.

Bob

http://i35.tinypic.com/23lnxaf.jpg
On a more serious note, I've had good luck with inconel safety-wire from aircraft spruce on my CHRA bolts. The chra flange thingy started leaking again after the last track event, but I don't really care enough to work on that anymore.

https://www.dormanproducts.com

Threaded Metric Fasteners, Double-Ended Studs Class 10.9

Not endorsing the quality, but 10.9 is better than 8.8. Most any auto parts store should be able to get these, or have their own line available.

Better how? "Better I didn't read the thread and think a harder bolt won't stretch" or "better I'm moron and didn't read the thread" or "I like to type shit on the internet that I know nothing about"?

looks like Dorman #292224. M10X1.5-52mm long would fit.

Bob

Grade 8.8 has a 660 MPa yield strength

Grade 10.9 has a 940 MPa yield strength

They have the same elastic modulus; same dimensions Thus the same elastic spring rate. The difference in yield strength means 10.9 can be stretched 42% more than a 8.8 bolt before its yield point is reached resulting in permanent deformation.

It is better

Bob

Expensive grade-10 crap lasted 5 laps on my car. The same number of laps the grade 8 lasted.

Bob, Hardware Sales here in bellingham has a really good stud selection, they even have some stainless steel studs I think. That is of course if you need something quick and dont have time to wait for it in the mail.

I said better, good enough is another issue.

I've had a little better luck thus far with the 10mm. but my manifold is a bit better for the turbo joint than the cast log setups I think. long runners long merge collector deply coutersunk studs to add grip lenght and stud holes that dont see the inside of the manifold all help some.

Bob

Yeah - do I think my studs will last forever? No. Do I think going from changing them every 3 weeks to every three years is worth the savings of a v-band system? Hell yeah!

Everyone wants ideal. I'm sure I could make a custom aluminum block for my car, too, but using the iron one is pretty good and very affordable. :-)

Perhaps it's better to make them easy to change, find something good, and swap them out just like on helicopters: Need it or not, off they go. Anything that acts funny (hard to put on, hard to put off, squishes as you put it on... is a candidate for replacement. My McMaster 10mm's were like a couple bucks each, so really, what's $20/year for studs? You certainly would spend $20 more a year on tires or brakes.... And there's less likelyhood of having to damage anything removing a broken or seized stud

bbundy,
You should construct a crane if you have not already. I talked to the guys at twins turbo and they say to put a crane on even cast manifolds and it will stop this problem.

Try dropping $200 to get on track, only to not be able to drive the car for more than 3-8 laps per session. It quickly becomes more important then. I was fine on the street with light torque and safety wire.

Word. It sucks to go to all of the trouble and expense of attending a track day only to be kept off of the track due to a mechanical failure. Plus you do not want to have to worry about stuff breaking while on the track which is hard to do if your car has known issues.

Agreed, I don't change mine that often. What I'm getting at is if you have a solution you know will last 5 track days, and you replace it every session or every other, you're golden - yes you're throwing away hardware with a few more track days in it, but it's a reasonable solution.

Crane?

I have a diving board thingy I made that supports the turbo off the motor mount bolts to the block very similar to a stock 323 GTX if that is what you mean. Made it out of mild steel first and it cracked made it out of 4130 and it hasn’t. I don’t have a cast manifold. It is a home built mild steel weld ell manifold. It’s got long equal length runners about the same length as the stock header. Turbo is mounted real low. I have had no cracking issues with the manifold.

The turbo flange has stayed tight over 10 times as long as I could get my cast Iron manifold to stay tight after I started being a faster driver. The cast manifold wouldn’t stay together for a single track day in the end.

Bob

I've seen pics of your set up. Is the crane/divingboard thingy on a heim joint at the chra? I'm asking, rather than getting all bossy.

Went to Napa they had “grade 5” I am assuming that means 8.8 studs in stock in napa boxes for $7.95 a pair in stock.

The same dimension Dorman Grade 10.9 studs were $1.05 each and will arrive in the morning.

Higer grade bolts are cheaper, how does that compute.

Bob

Bob

It is a flat piece of 1/8" steel It is bolted with two bolts a bracket that bolts to the forward two bolts on the engine mount. It has a single bolt bolting it to a boss welded on the turbine outlet flange on the bottom side, no heim joints. It will spring up and down a slight amount sort of like a diving board alowing for some themal expansion movement of the manifold. Pretty rigid in cross car or for/aft directions. I think it does a good job of eliminating lower frequancy resonance vibrations and isolating the manifold from bending moments induced by the downpipe.

Bob

Is that still the one next to West Marine on Commercial with the crusty old machinist in the back? Been a few years...