Intake Manifold Studs
 

I was finally bitten. When pulling my intake manifold off one nut just fell off with the half stud in it. What are you track people doing for intake manifold studs? They seem to fail left and right for the auto-x people, the csp car ended up replacing an entire set worth this season IIRC. They're m8x1.25 I need to pull a good one to get the length. Do we just replace with OEM as the break or have an upgraded option? Mcmaster doesnt have 10.9 studs, but they do have 4140 for pressure bolted connections in high pressure systems. Minimum tensile strength of 124,000 psi and max hardness of Rockwell C35, which is in between class 8.8 and class 10.9 for both strength and hardness.

I haven't had any issues with mine. Are you maybe overtorquing them? I remember them having a pretty low torque range.

I tightened them with a 1/4" drive ratchet so I doubt I yielded it. The failure looks like fatigue, it didn't look over torqued.

...maybe the intake manifold brace serves a purpose after all...

I have been racing mine for the past year and previous owner for 4 years with out any problem..

This is WITH the brace...1600cc motor, though I doubt that makes a difference....

Now the exhaust manifold, thats a different story!

Yeah, I've been looking some more and it looks like this is just an issue that us cone dodging, weight weenies that rev the car to the moon and back have to deal with.

I suspect the revving is the culprit.

I've done about a hundred autoxes on mine, with nary an intake manifold stud problem so far, but I don't rev it above the stock 7200 (here's little point with a a 2560).

--Ian

So bust out the sawsall, grinder and other associated metal removal tools and make the intake lighter! :giggle: Less mass means less torque on those studs.

The thing is freaking heavy, its also borrowed. :giggle:

tap the bolts out for a larger size- best option, not easy to do properly in the car.
use higher grade bolts (not as ductile though in most cases, so it likely wont help)
use the intake manifold bracket - if your a weight weenie for the 1/2 lb that the brace isare, drill some holes in it in the middle of the web, leave the outside of the web for strength.

Then I'd vote for bracing. Just like on the turbo/exhaust side of things. I actually had my turbo come off the manifold recently because of a broken exhaust hanger in the rear.

Sucks to add weight but it might be necessary. Also you can probably fab up something lighter and just as good than the factory brace with a swaged rod or turnbuckle.

But the turn buckle wont work, too many axis of movement, it just becomes a point for the manifold to rotate around. It needs a solid connection if its going to have a brace.

I took a look back at one of the old engineering texts, my failure may potentially be an under torqued fastener, or just a lack of yield strength in the fastener. I'm going to find some class 10.9 studs, and actually use a torque wrench. And probably re-calculate the actual torque spec to be 60% of yield for the new studs.

If you are recreating the factory type brace, I don't see how a turn buckle would have too much motion. Lock the buckle into the length you want. I'm not saying put rod ends on it.

That seems more expensive than just drilling a bunch of holes in the stock brace. :giggle: Or just running stronger studs with a re-calculated torque spec.

just don't bottom them out in the head, not really sure how much space is back there. that won't be fun to get out...

btw, are you running a phenolic intake manifold gasket by chance?

How much does the stock brace weigh?

and is the weight cost REALLY worth the hassle?

No stupid plastic gasket. I havent weight the brace and associate fasteners but it must be around 5 pounds. Its also in the way of where I want to put my power steering pump maybe.

:dunno: I have a piles of unused parts from all sorts of stuff. This would be nothing to scrounge up something to create it. Cost? You must not value your time very much. Taking much weight out of the factory brace is going to take a while even with a drill press.

Even cheaper? A piece of square or round tubing could be abused in pretty quick fashion for this and probably still lighter than the abused factory one.

It looks like Dorman has some M8x1.25 10.9 studs.
Dorman Products - Double-Ended Studs Class 10.9

5 lbs? you are crazy. that brace is no more than 1.5 lbs with the 3 bolts it needs.

Solution, a lighter intake that is also *SP legal. Coming soon.

OP question, check with ARP, they make all kinds of products that don't have a specific application.

Take a pre-game dump before you race.

I need my roommate to get his ass back up here before I loose my access to the machine shop so we can make two sets of the sweet barrel throttle body itbs.

ARP does sell a set of 300 series stainless studs for this, the ever come with a spare. Not sure if they're stronger or not, but they are more than twice as expensive as going inconel.

Thats weight towards the rear of the car, I like that weight. its weight on the nose I want to get rid of. And minimum weight doesnt include driver. :noob:

Good point.

When you race the car, it doesn't have a driver anyways.

Mines remote control, its street mod legal. :dealwithit:

I've looked into ITBs and I wasn't too excited about tuning part throttle etc on a forced induction. But YMMV.

Not a problem with blended alpha-n and SD. Though I would seriously consider going to a blow through maf setup once that manifold made it onto the car.

AIDS. So much AIDS.


http://s3.amazonaws.com/data.tumblr....2Fs6JWI%3D#_=_

:vash: MAF is better :fawk:

Than what? A root canal?

Yeah, the OEM intake manifold brace is a featherweight. I only took it off mine because it's in the way of oil cooler hose routing.

--Ian

i ran some arp studs with 12pt nuts, just measure your shit an order them. I'm sure they are better steel than anything factory.

Dorman 675-579 looks like the winner, will order next week.

That part fits and should be stronger than stock. One broke when I took the manifold off after torquing them to the upper end of the factory spec with my bending beam. Top front one, which broke before, and is the one I hear other breaking most often. I'm just going to run the brace.

Just installed the ARP SS studs in my head. You want them. They are rated for 170,000 PSI plus. They include washers and 12 point nuts. If one of these breaks.....there is no way to keep them from breaking. Sure...$109 is a lot for 10 studs.....but my time is worth something...and I wont need to worry about changing these again.....I hope

don't tease - part number?

I ordered 400-8024. I needed 51mm long studs due to the blower manifold. If you are using a stock intake you might be able to use stock length studs. 400-8023 are 45mm long, 400-8022 are 38mm, 400-8021 32mm.

Wow I've never broken an intake stud. Use a hondata gasket and no brace. My manifold is defeatured and lightened though.

My situation is different than Leafy's or yours. I have @ 30lbs of intake and Whippple hanging off that side of the motor.

Yeah I'm still breaking them while running the brace, just less of them. Theres already 2 in the manifold right now that I felt let go when torquing them this last time, but fuck it with the vics manifold its way too big of a pain in the dick to fix. Next time this manifold comes off its being replaced.

I was torquing all of them to 18ftlbs with the bending beam, the two that I'm sure are going to come out broken started just turning with no increase in force around 12ftlbs. Theres no fucking way they're breaking from over torquing for me they look fine but must have developed cracks in the thread root that I didnt notice when I inspected all of them.

I think your the only person to have this problem bro. with the stock brace there should be no reason that they are shearing off besides installer error.

I did run the car with these studs and no brace so the damage might have already been done. But I'm leaning on blaming the 8500 rpms.

Im using a 94-97 manifold. heavily modified and made to fit a 99 head its a few pounds lighter than stock and might be 8 or 9 pounds lighter than a Vics. No EGR features no bracing no casting flash and with extra cast material and webs etc ground out removed and smoothed over. And no intake manifold issues with 8600 rpm rev limit.

Is there enough clearance to drill/tap larger and use exhaust manifold studs on the intake side?

--Ian

We had this issue on Laz, only when I used my shitty torque wrench and over torqued all of them to probably 30ft/lbs instead of 14-19.

We replaced all of them with new OEM studs, and used locktite on both sides. We'll try to report back at the end of the season with results.

Something no one's discussed, but the stock brace is molded to give easier access to the oil filter. Add in a oil/water cooler, oil cooler sandwich plate, and/or sensor plate, and/or an oversized filter, and there's no way it'll clear.

I've snapped a couple here or there, but it never seemed to be a chronic problem. 30lb of supercharger would probably change that. Eric, I'm surprised you haven't considered a brace - trying to keep the weight off?

I made a brace for the manifold. I think my issues went as follows. Blower manifold flange was too think to use stock length studs. I (like an idiot) went to the local hardware store and found the proper length "automotive studs" which I later found out to be class 5 hardware. So this off season rather than only half fixing the problem, I did what I do and went overboard with the ARP hardware. Like all ARP stuff I was impressed with the quality and would recommend those studs to anyone. (but they are a bit spendy)

Running factory studs in mine with the same charger hanging off the side that TNTUBA has. Zero issues.

Drive harder. :giggle:

Your setup isn't exactly like mine. :/ The catalyst for my issues was the thickness of the manifold flange requiring longer studs.

I know. That wasn't a poke at you. We fabbed our own intake with a flange thickness to utilize the factory studs. The point was to everyone else that I have substantially more weight than a factory intake hanging off the side of the engine on the factory studs.

I just found the 3 studs surrounding the #1 cylinder broken. They all broke within the nut. two of them still had the nut on by a thread, but the end of the stud was gone.

I was not running a brace. I did have a fabricated brace on it, but the lower attachment point had failed, so I just took it off. looks like I need to improve the lower mount.

Those of you breaking intake manifold studs, is 8000+rpm the common denominator? If so, are you running an aftermarket balancer? How about fully balanced rotating assembly? (Wondering if the SuperMiata balancer and the like would reduce high rpm vibration enough to combat vibration related failures?)

Mine was balanced by trackspeed when they built it and has a 949 damper on it.

Rotating assembly was static and spin balanced and runs a ATI damper. Still broke several.

Jury is still out on the ARPs....but so far so good.

Stock, stock, stock

Never seen a stud break like this, doesn't make sense. It's like the threads within the nuts crumbled and failed.

Yup, thats how all mine have done it. Between old OEM, new OEM, and Doorman grade 8.

I used a grade 10.9 stud (Rockford) and used Locktite blue on the nuts. Maybe the thread locker can support the threads better?

One track day!
 

https://www.miataturbo.net/attachmen...ine=1434225019


One failed stud, (I removed the other one in the photo)
Never saw above 7400, brace was installed and did not fail this time.
Looks like I will drop some coin on the ARP studs, since the heads coming off for valve seals.

Was your crank knife edged, or any weight taken off for the purposes of "lightweighting"?