|
|
|
#16
|
||||
|
||||
so the
blocks have steel insterts in the threads? are they aluminmu blocks?
inquireing minds want to know. tom w
__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#17
|
||||
|
||||
Quote:
Boost levels are limited by fuel octain levels so no he is not running 800 hp all the time racing fuel is damned pricey
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche Last edited by boneheaddoctor; 11-02-2005 at 09:06 AM. |
#18
|
||||
|
||||
Quote:
These are on stock unmodified crankshafts....hondas have bulletproof cranks... But my basic point is these are being stressed way beyond factory levels..so Studs make a noticible difference...On a 606 or a 603 they have decent head bolts...will the engine be stressed enough for the stock head bolt shortcomings to become apparent? I will guess probibly not...but studs are a better alternative... One situation where studs would have made a huge difference in a stock application would have been the GM 5.7 diesel......early headbolts were NOT up to the task....Studs would have made all the difference in those before better headbolts were made (way too late in the game)
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche Last edited by boneheaddoctor; 11-02-2005 at 10:27 AM. |
#19
|
||||
|
||||
Back to the topic but are you sure the head and the block is flat?
__________________
01 Ford Excursion Powerstroke 99 E300 Turbodiesel 91 Vette with 383 motor 05 Polaris Sportsman 800 EFI 06 Polaris Sportsman 500 EFI 03 SeaDoo GTX SC Red 03 SeaDoo GTX SC Yellow 04 Tailgator 21 ft Toy Hauler 11 Harley Davidson 883 SuperLow |
#20
|
|||
|
|||
The head better be flat after a $700+ bill. I have no reason to suspect the block would have warped at all (no excessive heat). The studs for the 102mm bolts are around $5.00, plus washers and nuts. However, at this point they're working on find the 115mm replacements. The length of those studs need to be 5.625" and I guess they have to dig deep in the obscure bins to find some (hopefully).
Matt |
#21
|
|||
|
|||
Bolt stretch and Hookes law
The problem that I see here, is getting the correct clamping force using studs and nuts. How do you accurately determine how much force is given by the installed stock bolt? This will be different than the force applied by the threads as you torque the bolt.
Note that all bolts and studs stretch when installed. It is the elastic force of the bolt or stud that is important, and the torque (for studs and nuts) or the plastic stretch (for these type of bolts) that determines this force. The plastic stretch of the bolt ensures that the pressure is evenly applied across the head, given that the bolts are properly designed. Now, with studs, you would want to keep the same clamping force. However, you also want the same clamping force once the head expands with heat. So the studs should stretch with force at *exactly* the same rate (hookean factor - making the assumption that the deformed bolt is close to hookean) as the pre-stretched stock bolts. Seems pretty much impossible. I wouldn't try it. |
#22
|
||||
|
||||
Quote:
__________________
01 Ford Excursion Powerstroke 99 E300 Turbodiesel 91 Vette with 383 motor 05 Polaris Sportsman 800 EFI 06 Polaris Sportsman 500 EFI 03 SeaDoo GTX SC Red 03 SeaDoo GTX SC Yellow 04 Tailgator 21 ft Toy Hauler 11 Harley Davidson 883 SuperLow |
#23
|
|||
|
|||
Never assume...
Quote:
I think your concept of using head studs is an excellent idea. I use them on a VW jetta diesel...about the only way to keep from blowing head gaskets with these. (Aluminum on cast iron...different rates of heat expansion, contraction... ) I've used them on other apps also. ARP head studs , last I saw, were rated at 190,000 psi tensile strength. Great quality...and with the usual fine threads on top and 12 pt nuts you can clamp that head down good.
__________________
Diesel-guy |
#24
|
||||
|
||||
I use ARP studs on my Nissan L28ET. They are rated for a higher torque than the stock bolts, and with the ARP lubricant you can be absolutely sure of the torque. Bolts are harder to torque consistently because you are twisting as well as tightening, and that adds an error in the torque indication. ARPs typically are not lock-tited, just threaded in hand-tight where they bottom out.
__________________
'83 240D with 617.952 and 2.88 '01 VW Beetle TDI '05 Jeep Liberty CRD '89 Toyota 4x4, needs 2L-T '78 280Z with L28ET - 12.86@110 Oil Burner Kartel #35 http://i16.photobucket.com/albums/b1...oD/bioclip.jpg |
#25
|
|||
|
|||
I will use the straight edge on the block to put my mind at rest. It's good to hear about the successes on other applications. Matt L, supposedly when the studs come from the manufaturer, they supply the correct torque sequence and pressure.
Matt |
#26
|
|||
|
|||
Humm,
In a bolt and nut combination, if you torque the bolt vs torquing the nut- you will get a difference in preload. Correction: Torque wrenches are LESS accurate than using angle. PERIOD. 15% variation in preload(force in the bolts). Some really big bolts (3-4inch shanks) will have a small hole drilled down the middle, then you can get delta L using a micrometer to get the preload correct. Angle is about plus or minus 5 %. You can make some stiffness assumptions and calculate the preload of the current setup vs the new studs. I'm assuming they are going to be 160 ksi or 180 ksi studs? Stretch bolts were first employed in aviation for more consistent preload. I'd suspect reverting to the old technology you may increase your chances of headgasket failures. These engines being Alumium head/Iron blocks will always have different coefficent of expansion differences which will work the joint regardless of the fastener selected. I'd bet headgasket life will not be much better. Torque should be a function of joint stiffness required.... ARP vs MB. Michael
__________________
Michael McGuire 83 300d 01 vw A4 TDI 66 Chevy Corsa 68 GMC V6 w/oD 86 300E |
#27
|
|||
|
|||
I picked up the head today, and the shop only had to take .004 to surface it. Now after seeing the head and where the studs will have to go, it looks like I only have 1/2" to work with in terms of height before it hits the cam tower. Hmmm. I'll know more tomorrow when I put them on the head to check tolerances. Still haven't found the right studs yet for pricing, but when I do I'll pass it on. The following is from the ARP website...
Studs also provide more accurate and consistent torque loading. Here’s why. When you use bolts to secure the head, the fastener is actually being “twisted” while it’s being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. If everything is right, the stud should be installed fingertight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run. Matt |
#28
|
|||
|
|||
I don't think you'll have room for the nuts in the counter sunk holes without some more machining. It may not be possible near the cam towers. Good luck keep us posted.
__________________
Bob D. Parrish, FL 1 SDL, 1 D, 1 TD, 1 Mog |
#29
|
||||
|
||||
it still
goes back to the threads in the block. they will only hold so much. putting a stronger stud in will not change their holding power. the more accurate torque readings will not affect the ultimate holding power of the bolts. the twisting loss of accuracy will have been considered in the design of the bolts and the torque values adjusted up accordingly. the factory stretch bolts will be hard to beat for accuracy of pull.
if you put in studs and torque to higher values it will stress the block more and may affect the sealing capacity of the head gasket from distortion of the block. although the factory engineers obviously have made some missteps on the aluminum head diesel engines i would be reluctant to deviate from the factory setup with out a lot of successful experience from someone out there with benzes. the stud scenario is not a panacea. there will be unforseen difficulties with it, i would bet. my $.02 tom w
__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#30
|
|||
|
|||
With studs you get a more accurate torque setting. With a bolt, you have some torque lost to the bolt itself twisting as you tighten it. (think torsion bar suspension). With studs and nuts, you are turning a nut (with washer beneath it) on a fixed stud. The stud is not turning, merely being stretched by the increasing torque. All bolts stretch whne they are tightened. Some are just more elastic than others. Going to studs was the solution for the diesel VW crowd. VW diesel engines were famous for blowing head gaskets and turbos only made it worse.
|
Bookmarks |
Thread Tools | |
Display Modes | |
|
|