Boostwerks Engineering Jeep 4.0 Titanium Manifold Stud Kit (V2.0) Review

Trevlaw

Trevlaw

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Decided to put up a short review on this Exhaust stud kit since I wasn't able to find a whole lot of info on them before buying them. I've got a very leaky exhaust manifold gasket that I will be replacing soon, and I wanted some upgraded hardware before diving into that project. First I checked ARP and wasn't able to find an exhaust bolt or stud kit for the 4.0, I think they used to make one but it doesn't appear they do anymore, though you could probably piece one together if you know what sizes you need.

The only kit I found available is from Boostwerks Engineering, it's his version 2.0 stud kit with custom washers and mechanical lock nuts all machined by Boostwerks out of Grade 6 titanium. They look absolutely awesome, his surface finishes are very nice on all three parts, but the proof is in the pudding.

The studs are 3/8"-16 on one end and 3/8-24 on the other end.

The major diameter spec for 3/8"-16 2a threads is .3737"-.3643"

The pitch diameter spec for 3/8"-16 2a is .3331"-.3287"

Boostwerks averaged .3715" for the major with a range of .371"-.372"

Pitch diameter averaged at .3274" with a range of .3269"-.3279"


Major diameter spec for 3/8"-24 2a is .3739"-.3667"

Pitch diameter spec for 3/8-24 2a is .3468"-.343"

Boostwerks averaged .3722" for the major with a range of .371"-.3735"

They averaged .343" for the pitch diameter with a range of .3428"-.3435"

I measured all 11 studs with my 0-1" Brown and Sharpe mic and a brand new set of Brown and Sharpe thread wires. Everything was very consistent, no significant tapers in the major or pitch diameters and most of the measurements were within spec, though all of the pitch diameters were towards the bottom of spec and some were out of spec by a thou or two on the 3/8"-16 thread. This may pose a problem in other applications, but for an exhaust stud a thou or two under the pitch diameter spec shouldn't be a problem at all.

All of the studs are broached on the 3/8-24 end with a 5/32" hex to aid installation. The hex looks very good, it doesn't appear to even have a witness mark on the flats from the drill before the broach, it is a fully formed, and nice snug fitting hex.

The minor diameters on his lock nuts were all consistent around .336", spec for 3/8"-24 2b is .330"-.340". I will be taking these into work to test with some thread gauges this weekend, but I don't expect any issues.

I certainly wouldn't hesitate to purchase these again in the future, $125 is pretty damn reasonable for the amount of machine work involved to produce the entire kit. I will continue to update this as I get the lock nuts measured and get the studs installed

IMG_20210713_125848953.jpg


IMG_20210704_161419199.jpg
 
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I am considering these studs. First goal would be easier install, second would be they don't loosen over time. Did they help either of these issues? Thanks,
 
Fluxor said:
I am considering these studs. First goal would be easier install, second would be they don't loosen over time. Did they help either of these issues? Thanks,
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So I did just recently get these put on. I used an OEM two piece manifold and each half of the manifold has one bolt hole and one slot that the studs pass through. You'll need to drill out the two bolt holes and use a carbide Burr, flap drum or something similar to widen the two slots as the diameter of the shoulder on the studs is too large to pass through. Not a big deal for me, and I think he mentioned on his site that may need to be done during the install.

The one part that I didn't understand, and I've been meaning to email him and ask him why, is that the nuts he makes are peened on the end to act like a lock nut. The ends of the stud have a pilot diameter before the threads start and when using a factory manifold with his washers, the studs are like an 1/8"-1/4" too short for the locking portion of the nut to actually engage on the threads.

I can get a picture in a little bit to show you what I mean. I still used them, but was a bit disappointed in that part. I've been meaning to go back and check to make sure they're tight, I've only had them on for maybe 1000 miles so far.

Also, if you're reusing your factory manifold make sure to check and see how flat it is while it's off. I have three pairs of factory manifolds, one which is pretty low miles and all of them are warped badly, with the middle port being .020-.030" proud of the other two
 
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Interesting that the stud is not long enough to engage the locking portion of the nut on the O.E manifold. I have the banks header so I will need to check. I would assume the O.E. manifold flange is thicker. seems like the studs could be long enough to work for either. Thanks for the feedback!
 
I will stick with McMaster carr studs and steel locknuts. Not rocket science for a motor that is prone to cracking manifolds…
 
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Fluxor said:
Interesting that the stud is not long enough to engage the locking portion of the nut on the O.E manifold. I have the banks header so I will need to check. I would assume the O.E. manifold flange is thicker. seems like the studs could be long enough to work for either. Thanks for the feedback!
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The OEM manifold flange is about as thin as I'd want for any exhaust manifold, so I don't think that's the main issue.

If the threaded portion was longer it'd be a 5/5, the machine work was top notch and he even goes to the trouble of setting up a rotary broach for one end of the stud just for installation purposes.

These are already version 2.0, I'm going to email him and see what he thinks, it's a pretty minor change to make for the manufacturing process, so hopefully he can address it and make a third rev.

It's a good deal for what you get, a similar stud on McMaster is going to run around $50 for them, plus nuts, washers and shipping.

I'm going to inspect the other manifolds I have, but I suspect they warp pretty good after their very first installation. Mine weren't very flat at all after 150k miles, I'd imagine if they were pulled off, machined flat again before they've cracked, and reinstalled that it would prolong their life some, though I don't have the kind of time to make any reasonable claim on that idea.
 
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You just go to the catalog online and search, all studs are coarse/fine thread and pick your length. Cheap and easy
 
astjp2 said:
You just go to the catalog online and search, all studs are coarse/fine thread and pick your length. Cheap and easy
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A 2" long 3/8-16 zinc plated grade 8 stud is $9.42 a piece. There's 11 studs. Another $7.69 for a package of suitable locknuts.

11 studs and a pack of nuts is $130 shipped and that doesn't include washers.
 
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Trevlaw said:
Cool, those should rust nicely.

Nobody is saying you can't find cheaper hardware. I just wanted to post a review of a nice product made by a small shop for an excellent price.

Not sure what your point is here
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Sometimes I think this forum should be renamed the "I'm not gonna pay a lot for this muffler" (or anything ELSE!) forum:
 
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Trevlaw said:
Decided to put up a short review on this Exhaust stud kit since I wasn't able to find a whole lot of info on them before buying them. I've got a very leaky exhaust manifold gasket that I will be replacing soon, and I wanted some upgraded hardware before diving into that project. First I checked ARP and wasn't able to find an exhaust bolt or stud kit for the 4.0, I think they used to make one but it doesn't appear they do anymore, though you could probably piece one together if you know what sizes you need.

The only kit I found available is from Boostwerks Engineering, it's his version 2.0 stud kit with custom washers and mechanical lock nuts all machined by Boostwerks out of Grade 6 titanium. They look absolutely awesome, his surface finishes are very nice on all three parts, but the proof is in the pudding.

The studs are 3/8"-16 on one end and 3/8-24 on the other end.

The major diameter spec for 3/8"-16 2a threads is .3737"-.3643"

The pitch diameter spec for 3/8"-16 2a is .3331"-.3287"

Boostwerks averaged .3715" for the major with a range of .371"-.372"

Pitch diameter averaged at .3274" with a range of .3269"-.3279"


Major diameter spec for 3/8"-24 2a is .3739"-.3667"

Pitch diameter spec for 3/8-24 2a is .3468"-.343"

Boostwerks averaged .3722" for the major with a range of .371"-.3735"

They averaged .343" for the pitch diameter with a range of .3428"-.3435"

I measured all 11 studs with my 0-1" Brown and Sharpe mic and a brand new set of Brown and Sharpe thread wires. Everything was very consistent, no significant tapers in the major or pitch diameters and most of the measurements were within spec, though all of the pitch diameters were towards the bottom of spec and some were out of spec by a thou or two on the 3/8"-16 thread. This may pose a problem in other applications, but for an exhaust stud a thou or two under the pitch diameter spec shouldn't be a problem at all.

All of the studs are broached on the 3/8-24 end with a 5/32" hex to aid installation. The hex looks very good, it doesn't appear to even have a witness mark on the flats from the drill before the broach, it is a fully formed, and nice snug fitting hex.

The minor diameters on his lock nuts were all consistent around .336", spec for 3/8"-24 2b is .330"-.340". I will be taking these into work to test with some thread gauges this weekend, but I don't expect any issues.

I certainly wouldn't hesitate to purchase these again in the future, $125 is pretty damn reasonable for the amount of machine work involved to produce the entire kit. I will continue to update this as I get the lock nuts measured and get the studs installed

View attachment 265137

View attachment 265138
Click to expand...

Thanks for this write up. I'm planning on getting ready to do this job in the spring, using this kit.. did you ever get an answer back from the seller on the studs being a little short? Did you have any issues with them coming lose because of this?
 
98Wrangler said:
Thanks for this write up. I'm planning on getting ready to do this job in the spring, using this kit.. did you ever get an answer back from the seller on the studs being a little short? Did you have any issues with them coming lose because of this?
Click to expand...

Well, I forgot again to message him. I just sent him a message now, his site says he'll probably get back to me within 48hrs and I can let you know what he says.

I haven't had any issues with the studs coming loose, they still look as good as new too.

If you're painting your manifold too, I had good success with brushing on the exhaust manifold coating offered by POR15. Has held up great over the past year.
 
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Trevlaw said:
Well, I forgot again to message him. I just sent him a message now, his site says he'll probably get back to me within 48hrs and I can let you know what he says.

I haven't had any issues with the studs coming loose, they still look as good as new too.

If you're painting your manifold too, I had good success with brushing on the exhaust manifold coating offered by POR15. Has held up great over the past year.
Click to expand...

Haha ok well thanks for contacting him about it, I appreciate that!. As fare as the studs that's great news since it's been about 2yrs. I'll keep in mind about the por 15, I've used there product on the hole bottom of my wrangler. Great stuff , so fare very happy with the product.
 
98Wrangler said:
Haha ok well thanks for contacting him about it, I appreciate that!. As fare as the studs that's great news since it's been about 2yrs. I'll keep in mind about the por 15, I've used there product on the hole bottom of my wrangler. Great stuff , so fare very happy with the product.
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No problem. Just to be clear, do not use the regular POR 15 on your exhaust, that won't end well lol.

This is the stuff I used. Brushed on easy, think I did one coat, maybe two.

https://www.google.com/amp/s/por15.com/a/s/products/high-temp
 
This must be one of those model year differences? I just did my intake and exhaust manifold gasket and I only had two studs. The rest were Grade 8 3/8-16 bolts with a heavy cone washer on them.
 
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