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Join Date: Jan 2000
Location: Hahira, GA, USA
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Stephen's six stud system?

Anyone using this setup? Opinions? I've got a 1.7 w/ dome tops and a 1.8 w/ 96's torn apart and am considering their 104's and an 84 crank. Before I jump into that kinda $$$ I want to have some input.
Thanks, Dave

Old 02-17-2000, 04:28 AM
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I am having a 2.8L engine built in San Diego to replace the 2.4L and it will have a six stud system, which is about the only way to keep the top of the engine on with big barrels and high compression. I guess it is better to beef up what will be the weak link in this chain and have the engine stay together longer. Good luck.
Old 02-17-2000, 06:23 AM
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Dave, what condition are your 96mm juggs in on that 1.8L? I ask as I've been looking to swap out my dished low compression 94mm's to try instead a set of flat top 96mm pistons/cylinders on my 2.0L, currently dismantled (and cost has been an issue).

I think the 96mm kit for the 1.8L has the same width of material at the cylinder top as the kit for the 2.0L, for a proper fit at the heads, as opposed to the 1.7L kit, which, I've been told, does not. If you are making the swap for the reason of hp gains, and not because of wear, let me know. I might be interested. Thanks.

--John in Louisiana
Old 02-17-2000, 11:46 PM
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The 1.7 and 1.8 use the exact same rods and crank (actually the PN on the rods is different but the parts themselves are the same). The stroke is something like 66mm (?) for the pistons to work the wrist pin is a specific distance from the top of the piston. The 2.0L crank (later 2.0L rods have a cut in them to aid in oil splash cooling the piston, but not until 78-79 or so) is 71mm (?) so to keep the cylinder the same length the piston pin is moved. In a nutshell if you put a 2.0L crank in amotor with 1.7 or 1.8L P/C's the piston will extend out of the bore 1/2" BTDT. Thought I could buy the cheap 1.7L BB kit and use the 2.0L crank and rods.

Also you are correct the 1.7L heads need to be opened up to work with 1.8L and 2.0L P/C's. There is no cost effective conversion to make 1.7L P/C's work with 1.8L or 2.0L heads.
Old 02-18-2000, 12:29 AM
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Yep JP you are right on the money. 1.7 & 1.8 are 66 stroke and the 2.0 is 71. I'm gonna use a stroker crank and rods. The 96's won't work w/ the 2L crank, too short. I am going to build up the 1.7 to have as a spare engine using the 96's.
What will probably happen is that I'll put the 1.7 in and continue to save for the BIG motor. It's not easy to plop down 2 grand for me!
Old 02-18-2000, 04:03 AM
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Also the rod journals are different sizes,66 has 55mm,71 has 50mm. The rods are a different length, too.

Dave, are you in Georgia? Get your oven?

When going to 81 stroke, you start having trouble with rod to cam clearance. It is not advisable to use smaller base circle cams unless you switch to T1 lifters. More case work. I'm using 5.325 length Eagle rods, chev dia. by vw width welded 78mm stroker. any more stroke and you should go to a forged after market crank, more money. I feel for street use and reasonable outlay, 78 is about max.
Old 02-18-2000, 10:26 AM
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Tom
Question about your crank rod set up - who did the welding grinding? I want to use a set of vw eagle rods on a 1.7 and could except, the type iv rod journal is .100 larger than the vw type 1. It just kills me you can buy 4 type 1 rods for $280 and type iv's are $700+.
neil
Old 02-18-2000, 10:56 AM
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Tom, yep! Got the oven! Now I gotta get the powder coat set-up. The deal I had on the blasting cabinet fell through. Oh well things go like that sometime.
I messed up my post in regards to the stroke. Should have been a 78 stroke.
How's the auto in the Notch coming along?
Old 02-18-2000, 11:27 AM
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I was quoted $400 for eagle rods from FAT new, same as what I got used for chev dia. x T1 width, 5.325 long. The cranks can be gotten from two sources that I talked to and looked at their stuff when I was last in Orange Co. They are FAT and European Motors. Both had some good stuff and good prices. Any reputable shop could grind down to a T1. Never asked how but have been told it works. There is a 72.5 x 94 running around up here that is very impressive for how mild the motor is. The 2L crank was counterweighted, offset ground, and rabbit rods were put in it. For pistons its using T1 94mm pistons with 22mm wrist pins, all which adds up to a bunch lighter. 48 idas and a decent cam and it makes around 140 hp. Not bad at all in a bug, or 914, or an early bus.
Old 02-18-2000, 07:11 PM
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oohhhh boy!! Just got a call from my local VW specialist machine shop, and guess what. My case is ready for pick up and so is all my balanced parts!! I can now start the trial assembly of my 78x104, Stephens HP 6 stud headed monster motor for my car!!!!! I should be able to answer a few questions regarding this engine in the near future. Unfortunately the car won't be ready for it for a couple of more months.

TaTa
Old 02-24-2000, 09:29 AM
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Don't really want to hear it Tom!!!
Really though, glad for ya. Let me know how it goes together. Keep GOOD notes. I'm saving the peenies and hundred dollar bills for mine! The fasty should be back toigether by NEXT summer. Man this stuff can take a while to do!
Dave
Old 02-24-2000, 06:32 PM
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I am probably not the only one that wants to know this...but could someone who has had the six stud system done to there engines post pictures take measuerments and tell what exactly is drilled?

Is the case actually drilled in to...i would imagine so because it would need to have a better seal at the base of the cylinder...thanks.
Paul
Old 02-24-2000, 07:21 PM
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If you can find their big ad in the VW mags you'll see what it looks like. The cylinder is a new casting that has two bosses cast into it at the 12:00 and 6:00 positions. These bosses have studs coming from them and then to bosses welded onto the heads. The combustion pressure isn't exerted on the case so the studs don't need to go all the way through.

The FATS PERFORMANCE 5 stud system is similar to what you are talking about. The 5th stud is tapped into the case and goes all the way to a welded in boss in the head. IMHO the MS system seems superior IF they figured out the problems of different length studs expanding at differnt rates along with the fact that the 4 stock studs are tapped into aluminium while the 2 new studs are in cast iron... that is if these are even issues.
Old 02-25-2000, 02:01 AM
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You are right on the 6 stud and the new cyl. The FAT way with the added lug on the case is difficult to get stock sheet metal on the engine, it was developed for off road and the 911 style fan shroud conversions. I should have some pix available within the week, these will be of me doing the case clearancing. I got a $75 digital camera so don't expect super pix. I do like the 6 stud and the head mods all look good to me. I'm building this motor for big mid-range power, not a top end screamer, real world kind of driving. And in another year or so (after the car is back together and "de-clunked") I will start on the turbo installation. Looking at no more than 8psi boost, this should be "adequate".
Old 02-25-2000, 06:32 AM
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I was thinking about this (holding cylinder heads on a type IV ) the other day and began to wonder if you could put a nut inside the case to hold the head stud. This would eliminate the worry of pulling the threads out of the case. Could you then also run higher torque numbers on the head bolts, say 50 ft-lbs?

I would welcome any comments on this.

Thanks,
neil
Old 02-26-2000, 06:21 AM
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I think you would need longer studs for one, then ther is a clearence issue. To distribute the force over the entire head would require welding in some gussets. If you only crank down on the 8 points that are already there I would bet it would simply warp the heads at operating temp. The T-1 had problems with pulled studs but the T-4 is pretty good until you get outta hand with compression.

BTW, as the motor heats up the working pressure on the head studs (effective torque rating) increases quite a bit. If you were to crank things down to 50 ft/lbs cold, the expanding aluminum will make this much higher. The studs might not strip out, they may crack the case.

Just my two and a half cents, I ain't no fancy engineer, so take it for what it's worth.
Old 02-27-2000, 01:58 PM
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Well, It looks great hanging on my engine stand, not ready to run but definitely getting closer. 2650 ccs of Big Motor Power! I was going to post pics of what it takes to clearance the case to drop a 78mm stroke crank in, but I didn't take any. That's because I didn't have to do ANYTHING to get it to drop in. On the combo I'm using, which is Eagle rods (22mm wrist pins, Chevy x T1 big end, 5.325 long) and a 78 counter-weighted (I think it came from Euro Motors)there is no clearance hacking required. The closest anything got was at the rod to cam lobe, this was about .085 and should be good to go. Now if you were to use a stock 2L or a T1 VW rod (a very good choice), there would be a little clearanceing required on the rod bolt to the top of the case, a very minor amount.

The T4 rods have got to be some of the most clunky rods ever built, Hell for stout, but very over-weight. The T1 rod option gets you a proven rod that routinely lives in 8500rpm engines and gets you a better Rod/Stroke ratio while getting rid of 100 grams of weight where it is very detrimental.Plus great value and a lot of choices (prepped stock or aftermarket, hugh selection available from numerous suppliers). This also keeps the crank journal at 55mm for maximum strength (2L cranks are 50mm and Chev journals are 2.1, about a wash) If I hadn't got my crank and rod used I would probably have gone this way.

Ahh, you are wondering about the 22mm pin vs. the 24mm stock T4 pin. This is again a spot where VW over built. Here's a tip for those that want to save a little cash. If you stay with stock 94mm barrels, you can get Forged 94mm T1 pistons for a whole bunch less money than a an aftermarket T4 piston. And again, it saves weight. The pin height is available in stock or stroker heights from a multitude of suppliers. Or you can go to 96mm drop ins and get a very small choice of options, but less looking on your part for the correct fit of all combos possible.

On to the 6 Stud. It looks good and to get the sheetmetal to fit took a bit of hammer work to make a clearance bump in the top sheet metal over the base of the cylinder (1 per cyl. required) where the cast-in lug is that receives the added head bolt. The size of these bumps is about 1.2" in diameter and about 1/2" high. A ball peen and a large socket worked well and took maybe an hour to tap out. The hardest part was the fitting of the tin below the cylinder. A bit of hacking and fitting was required here and definitely required for good cooling around the cyl..

I'm back-ordered on my forged pistons so I'm at a stopping point on the trial fitting of everything. So Far, I like how everything is going together, it's been easier than I expected. I have gotten great support from my local machine shop on the little stuff and can't thank them enough. They are Northwest Con Rod here in Seattle.

Another installment in the future. I hope this has answered a few questions without raiseing too many new ones. Just another way of getting a big boost in power.

Old 03-05-2000, 07:05 AM
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