ARP Head Studs

You would also have to remove the EGR to get to the top left bolt. Its not difficult technically, just a pain to remove the old bolts, be sure you have a good wrench, socket, and breaker bar!

No mileage increase for me yet. Got 43.3 mpg on my last tank 70% hwy 30% city, hwy at 75 mostly, some 65mph.

Well, just ordered 3 sets--on backorder until the 16th
*sigh*
-BB

BleachedBora said:

Well, just ordered 3 sets--on backorder until the 16th
*sigh*
-BB

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I don't think you should worry....mine said backordered for 7-10 days too but they showed up in 4...
They just probably say it to protect them selves...
Summit is a huge company and i think if anyone else is on back order they will be the first to get restock..

plus they send theese $15.00 Summit store coupons with each order ...we could gather them all up for something lol

frugality said:

By then you'll be ready for the AARP head studs...

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that's pretty witty !!!

oldpoopie said:

if it aint broke, dont fix it.

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Good quote!! I saw a bumpersticker yesterday. "If it ain't broke, keep fixing it until it is."

I've been guilty of this a few times..

Turbodude1 said:

Good quote!! I saw a bumpersticker yesterday. "If it ain't broke, keep fixing it until it is."

I've been guilty of this a few times..

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Yup - that's me!

Did mine last night - a pretty easy mod. We'll see in a couple tanks of fuel if there is any MPG benefit - I'll drive it like always.

MCA

Installed today, I did not have to remove any EGR components to R&R the bolts/studs.


I'll report back after a few tanks of fuel with MPG numbers.

Jack you have the short tool for the head bolts. Most are about 6 inches(hey now!) and thus need EGR removal.

Ahhhh yes, mine is only about 2 1/2" I had the grinder ready if I needed to cut it shorter though...

jackbombay said:

Ahhhh yes, mine is only about 2 1/2" I had the grinder ready if I needed to cut it shorter though...

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*cringe and cradle my own tool in sympathy*

Ohhh...THAT tool. Never mind.

I've used theses on 1.5 L Diesels

I used studs on an old 1.5 D . The old diesels were prone to head gasket failures .

The larger stretch bolts in later 1.6 , 2.0 , & 2.4 L VW/Audi Diesels stopped the head gasket failures . On the old 1.5s the only thing we could do to stop the head gasket failures was to install high strength studs . And that worked well to fix the issues .

I also installed studs on a Toyota TD Camery in the late 80s to put a stop to head gasket failures .

I have a 1Z TDI and have thought long and hard about upgrading the engines to studs due to so many head gaskets I've seen blown on 1Z engiines .

BlakGolf said:

we have had to retorque on gassers if we didnt take the undercut option on the nuts. sounds like a interesting subject on a tdi. i had never heard about it in the short while that ive been on the forum

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The older style head gasket on IDI diesels used stretch bolts that required another 1/4 turn @ 1,000 miles after a new head gasket is installed . On the older style engines the solid head gasket would become pinched and the stretch bolts would twist instead on tighten after a certian point . After 1,000 miles the hot & cold cycles would cause the stretch bolts to untwist and loosen . So a 1/4 turn was required to reclamp down the head .

On newer engines IDIs and TDIs a mesh type head gasket of metal and sealer is used doing away with bolt twisting problem of earlier engines . That result has done away with a required retorquing @ 1,000 miles .

Very interesting thread. I wouldn't have thunk bolts could increase MPG.

I want a few more people to claim higher MPG numbers before I dive in.

michael.

Compression testing with ARP bolts

It would be interesting to see a compression test under load before and after ARP bolts are installed.

michael. said:

Very interesting thread. I wouldn't have thunk bolts could increase MPG.

I want a few more people to claim higher MPG numbers before I dive in.

michael.

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Yeah, well some of us have to be suckers ... er, guinea pigs.

MCA

My mileage deffinetly got hiegher...i even put in the R520's just before the ARPs and still with all that fuel it got better than before the nozzle install

Well, If i can get someone (oldpoopie) to compression test my car, I'll see what the change is...

I got a consistent 39 before the change. Granted I did a head gasket at the same time but on only a half tank with the studs and half the tank on the old bolts fuel economy went to 46. Same driving, same roads. It will be interesting to see where this tank ends up.

BoosTDIt...are you going to be attending Impexfest and would you be willing to guide me through the install for say....the cost of Saturday night's dinner and drinks??????

Mind you I don't do a whole lot of wrenching on my own beyond oil changes...wheel swaps...fuel filter...although I have always helped with TB changes...head gasket changes ect...on other cars.

I'm really curious to see if those of us out there with modded cars that still get 46-50 mpg will see an increase in mileage. I don't flog the car a whole lot due to my type of commute and the need to KNOW I have a reliable daily driver. Sure I use the power for highway on ramps and to pull away from people who are driving like morons on the road....but for the most part I keep the power in reserve.

This is an off the wall theory...but is it possible that these studs help more for people that flog thier cars by helping to keep compression high? Meaning...when you have a modded car and you really use the power are the stock head bolts flexing enough under that (beyond designed power) situation that would be causing a slight drop in cylinder compression thus causing the lower mileage effect (beyond the extra amount of fuel being injected of course)

Which leads to the next question....by going to the better studs and then using all of the "mod" power would you then be putting even more undue stress on the motor internals that would have been partially dissapated by the previously lower compression numbers with the stock bolts?

I would love to see a dyno comparision from a before and after stud upgrade on an already power modded car. If my theory is correct then you should see higher numbers afterwards...but with a coresponding increase in internal stress. It is certainly better off for the gasket...but at what cost to the overall internal long term health would be my question.

Again...this is ALL hypothetical from a guy that has zero experience in diesel motor development ect....I have only hung around a few gasser motorheads in the past.

Yeah but the theory does hold relavance. I am still undecided about getting this done, but if I do I will dyno. I had a dyno recently done and ahven't changed anything since then. I've yet to buy them, but it might be on my list of things to do in the near future.

My mileage got a bit higher, judging from how far I hit each gauge mark. Last tank was better than before, but now I have a mixed situation of some short trips and some highway. I didn't notice much difference in smoke, but then I have been overfueling and need to change the IQ ASAP.

I will see how the headstuds affect mileage when I move back cross country to New York next week (from Los Angeles).

I ordered mine from Summit the other day.. The main reason I'm doing this is because for some reason I don't like stretch bolts.. I had to upgrade the head bolts on my one gasser because of chronic head gasket failures, and the compression ratio is only about 10.5:1... I haven't had to change one yet since changing over to the ARP studs three years ago.. I guess anything that keeps the head firmly bolted to the block is a good thing, especially on modified engines..
I'd be interested in seeing dyno results before and after the change..

ofhs93 said:

by going to the better studs and then using all of the "mod" power would you then be putting even more undue stress on the motor internals that would have been partially dissapated by the previously lower compression numbers with the stock bolts?

I would love to see a dyno comparision from a before and after stud upgrade on an already power modded car. If my theory is correct then you should see higher numbers afterwards...but with a coresponding increase in internal stress. It is certainly better off for the gasket...but at what cost to the overall internal long term health would be my question.

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Yes, this could place more stress on the internals. Just like chips or injectors do, by effectively increasing the power output. The higher the power output/more modded, the more of an effect these will have.
The biggest drawback to them is that the head bolts are no longer the "safety valve." If you produce too much power you don't blow the headgasket, but more likely the rods. (Something has to be the first to go.)
These engines will handle more than just chip and injectors, so if you stay within reason you shouldn't have to worry.

What is within reason on the rods? 22 psi?

DanEboy said:

When replacing studs the head gasket has already been in use for some time and has already been compressed with heat! Retorqueing is more of a concern with a new head gasket and then it still depends on the construction of the gasket. Some manufacturers say retorqueing is not necessary.
Also, on the subject of why head studs may result in increased MPG...
I understand that besides better clamping force the other benefit is by having the stud fully seated in the block you effectively spread out the force on the block thereby decreasing bore distortion. A more round bore makes for a better seal to the rings. And with 19:1 compression even a little better seal should make for more pressure on the top of the piston!
Less blowby better economy!!!

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Ring Seal, Ring Seal, Ring Seal!!!
I've read that the Nascar engine builders run coolant through the block at operating temperatures with torque plates & head gaskets & studs (both head and mains) installed to torque specs while performing the final hone on the bores!
Compression yields power! After ignition keeping pressure above piston pushes it down with more force!

Just can't see it.

I don't understand how head studs ALONE can have any effect on
an engine regarding fuel mileage.
If you put on a different head gasket, that is NOT just studs.
(gasket might be thinner(higher compression) or old gasket might be leaky)
But just studs?? Studs are usually for longevity, not what the thread is
claiming.
No offence guys, but I think you are peeing in the wind with this idea....

Sorry,
Bill

40X40 said:

I don't understand how head studs ALONE can have any effect on
an engine regarding fuel mileage.
If you put on a different head gasket, that is NOT just studs.
(gasket might be thinner(higher compression) or old gasket might be leaky)
But just studs?? Studs are usually for longevity, not what the thread is
claiming.
No offence guys, but I think you are peeing in the wind with this idea....

Sorry,
Bill

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If you read through the entire 1.5 page where the discribtion is discused ,not the ordering and prices info...you'll find your answer

Hi Bill,

I believe the hypothesis (not a theory yet) is that the OE bolts - being stretch bolts - can in an engine that has been extensively modified, allow minor leakage and loss of compression. The swap to non-stretch variety studs is hypothesized to restore the compression to where it is supposed to be and brings the MPG back to where it's supposed to be - not a snake oil type MPG enhancer - just a fix of a problem that is robbing MPG. As I mentioned in an earlier post, I don't know if it's going to work for my car or not - I'll have a better idea in a full tank of two.

MCA

calling DBW, please give your opinion.
OK, I read the thread (again).
IMNSHO a head gasket is either blown or not.....
no in between.
if your HG is leaking (blown) you install a new one(for repair) and studs(for
repair longevity).
if head gasket is not leaking, then see my prior post (re: peeing into wind)
Bill