Head Studs vs. Head Bolts
 

Which is better for strength and reliability? What are the other pros and cons?

Studs provide more strength and are more applicable for boosted or high HP applications. Bolts are sufficient for stock/stock-ish configurations. I prefer ARP.

I agree that studs provide more strength but not that bolts aren't sufficient for boosted applications. I'm running ARP bolts on both the Cobra and Chevelle and have never had an issue with a head lifting. The Cobra is pushing 11-12 psi and the Chevelle has 12.25:1 compression and I run a 250 shot of nitrous to it. I'd say bolts will work just fine for RxSnake.

I'm on your side brother. I never gave HP ratings, I merely stated the studs were for more power. I have about 460 RWHP with 13 lbs on a dyno jet and have arp head bolts. I also think my setup is fairly mild considering... If I were to push 500 rwhp+ I would prefer studs.

Just if we're comparing studs to bolts there is no reason to run bolts over studs. We should especially consider the type of blower going on to RXsnake. Carb and a roots style should have studs.

Bolts make it easier to remove the heads with the engine in the car. If we already have bolts to use there is no reason to go out and buy a set of studs.

The Chevelle put down 461 rwhp on just the engine. With the 250 shot it should be over 600 rwhp. I have no fear in the bolts not holding up. They have been for the past 6 years. But then again I'm also using a two bolt main block with a cast crank and running 10 flat at 133 with a 12 bolt rearend that still has the original axles in it.

The only 2 studs that are the problem is the back 2 on each side. Remove these and there is no reason why they cant be removed in the car.

You dont count, you dont push your car nearly as hard as we do here. :sm_laughing:

SBF is notorious for having head gasket issues with boost.

I'd say Ron's car is a freak but I do know he's been through a few sets of head gaskets

Not in the Cobra. I leave the headers on so I wouldn't be able to remove them with studs. I'd have to remove all the studs to get them out.

On the Chevelle, I'd be able to remove the passenger side head but not the drivers because the brake booster is in the way.

I've replaced the head gaskets once in the Cobra because I was using the stock replacment Felpro and I got a coolant leak. The MLS ones I've had no problem with.

I've also had to replace one set on the Chevelle but that was because the first time I ran the nitrous I forgot to retard the timing and it detonated and reuined the head gaskets.

As fasteners, it's clear studs are objectively superior. The price difference is not really such a big deal when we're talking about an engine system anyway. The benefit of being able to remove heads in car is nice, but in a car that will be as radically stripped as the Snake, pulling the engine may not be much of a big deal really. I'm 99% sure bolts will be adequate as the estimated power <= 500RWHP and I don't see doing much to make it more than that. My onnly slilght concern is that's a big dumb simple roots blower that probably rocks the hell out of the intake and puts a more lateral force on the heads than they'd ever get with NA or Procharger etc. Whether it's enough to subtantively increase risk I don't know. Curious what Joe runs because he's run this combo and related for years.

Guy, for reference what's the price difference bolts vs. studs?

Even removing all the studs isnt that big a deal, they're allen tipped and remove just like a bolt.

Your car is a freak, there are countless guys on corral and yellow bullet who are plagued with HG issues even after studs. SBF are notorious for blowing head gaskets.

Check summit for ARP stuff. Pro Comp studs are about $44

Oh hell if the Pro Comp is OE equivalent to ARP and a set of studs <$50, it's a non-issue. Studs it'll be. The engine is outside of the car and will be fully assmebled before dropping. As stated before it will always be stripped (never A/C, heater, etc.) so even IF it has to be removed it won't be near the hassle it is on road cars. Fahget about it.

I ran ARP bolts. I blew a head gasket almost immediately, but then switched to MLS and never had a problem. Well, at least not with the head gaskets.

When held in the hand its difficult to tell the difference. ARP is definitely superior but we havnt had issues with the procomp studs.

Ok, on quality, how about ARP bolts (which apparently you have) vs. Pro Comp studs?

Not sure what you mean, I have both procomp and arp studs on various motors. I also have a set of arp head bolts. The spare motor with forged internals has arp head and main studs. No issues with pro comp so far. I'd say they're a good bet.

Give Eddy a call and tell him you want the felpro 1133 head gasket and tell him you're from motorgen that way you pay over the phone.

Haha, thats not a biased poll. Why not phrase it: which do you prefer, spending $60 on a product, or $130 on a comparable product?

No one is contesting, nor would anyone contest that studs are better than bolts. Mine was a cost vs. benefit argument. Besides I conceeded that with a ten bolt cyl head design even Id shell out the extra cash.

Heres another idea for a poll, how many of you have PERSONALLY experiened head bolt failure?Doubt we'll have even one member.

Btw, just voted on studs.

Ben, stay away from pro comp crap. I went through a set of pro comp rockers in 15k miles. We'll be taking the heads off so many times, ARP will save money in the long run.

Last post I promise, gotta stop reading backwards.

If we cant take the heads off with the studs, Id go with bolts. Especially because Ron has a more serious version of the same motor thats apparently doing fine.

Id hop on the rotary forums and find out if theres wiggle room in 2nd gens.

Too late. Bought studs, $55 from Guy's ProComp source. The motor is out and will be assembled on the stand. I *suspect* there will be room in the engine bay as well since it will be all bare bones. Even the vacuum booster is not so large. We'll see. :nuts:

I'm not advocating all pro comp stuff but their studs are great and last. Their heads, rockers and anything that moves are crap. Their pushrods, studs, carb intakes, and lifters are all of decent quality for the money. Shawn at Pacific Engine have been running them for years.

Hard to compare. Rons motor is a freak, plus a centri is a totally different stress then a roots. Hundreds of guys with sbf's are having head gasket issues with studs. Just not a good deck.

$55 for studs is a steal from what Ive seen, ARP wanted 130 for my sbc, but then again its 20 studs not 32

Its the same cost for a sbf. ARP is getting a little out of hand.

Ps, cyl pressure is cyl pressure. You could make the argument that roots blowers blow hotter air, but I dont think anyone has more boost with a higher inlet temp than Ron

If only it was as simple as that, the way the roots puts stress on the heads is completely different then a centri since its constantly stressing them, the KB fox guys have an issue with it, they have even higher inlet temps at lower boost and the threads are a plenty. Like I said, Rons car is a freak. Dan Pina the drift patrol driver has an identical setup to Ron and I and he has always been plagued with head gasket issues. He even has the big daddy boss r block with 1/2" deck hardware and he is still plagued with them.

The SBF sucks monkey dick for boost, n/a they're great, but any power adder has great potential for problems

Assuming inlet temps are the same (and theyre usually not, but you make up the difference by running a lower boost) explain to me how roots cylinder pressure is different from centri or turbo cyl pressure?

Once the valve closes with x amount of boost at x temp and the engine mixes and compresses the air on its own from that point. Wheres the difference? Splain it to me lucy?

Hint, its not. The only difference is with the inlet temps.

First as far as I know the old roots dont have a bypass, so your theory about once you let off the throttle and the valve closes and everything goes away doesnt work. Second i'm talking about the actual stress of the blower itself. Its alot of paracitic drag to begine with and the fact its directly fastened to the heads makes a HUGE difference from a centri or turbo. Every time boost build(and it builds quick with a roots) it immediately stresses the deck and heads. Not so good for head gaskets. Roots also run hotter then a centri.

From what I can imagine and know about physics, I'm gonna have to agree with Guy. A Centri or Turbo is blowing compressed air into the intake, on a roots, you have a very large spinning mass as part of the intake, it must be torqing into and away from the heads all the time; a kind of ratcheting effect . . . 10s of thousands of times. Mechanically, it seems like a much more violent environment/system.

That's exactly what happens. Ed Curtis has confirmed this and there is a reason why the NHRA requires blower straps for roots applications.

I wasnt thinking physically more stressful, but ya, I could def see that.

Actually Ive seen a roots blower pop off of a motor before, but it popped off at the base plate/ blower intake manifold, not at the heads.

Wut?? SBF sucks for boost? That's new to me...

Tis true. Talk to me when you run your car as hard as Ron and I do. His car is a freak, venture over to corner carvers and yellow bullet and you'll see how many sbf dudes are having head gaskets issues.

Did factory boosted SBFs (e.g., Cobra) have similar common problems? Maybe it's a common problem of people trying to reach for power on the cheap. I don't think Joe, who has run boosted motors hard has had any kind of unusual HG problems. :huh:

Completely different engine OHV vs OHC. The 4.6 in the cobra is good for about 800rwhp on stock internals. Modular motors were meant for boost. Sbf not so much. I definitely think it makes a HUGE difference if you plan out the hardware you're using and use an appropriate cam. I know the boosted road course guys are plagued with problems. There are plenty of dudes (like Justin) who make great power and rarely race and they'll last. Problem is the entire sbf is fighting itself when making power 450+ is where you start rolling the dice every time you race your can cause the block likes to spilt itself in half.

I forget what they're called, but doesn't just a little reinforcement across the pan and valley up that a couple hundred HP?

For a sbf? No, girdles just keep all your shit from flying all over the place when it breaks. Maybe 75hp if you have a valley girdle and main girdle, maybe...

Is one of your foxes actually blown and running? Whats your setup? I thought you were just putting stuff together.

And Ive heard girdles are for strength too. Seems like this week you just cant type anything that I dont disagree with. (And yes that was a proper double negative. Suck that high school language arts teachers.)