Silverlake Projects case through bolts

[dcpuddy]

Has anyone used these? They're a bit cheaper than the APR through bolts but I can't find much about them online.

https://www.silverlakeprojects.com/collections/porsche-911/products/porsche-engine-case-through-bolts

[prschmn]

Why do you feel you need to upgrade them? I don't unless it's a very serious race car.

[dcpuddy]

Originally Posted by prschmn

Why do you feel you need to upgrade them? I don't unless it's a very serious race car.

It’s for a high compression motor that’ll be used primarily for track days.

[prschmn]

Al or Mag case? Displacement?

[dcpuddy]

2.7 mag case. P&P heads, DC60 cams, 46mm webers.

[prschmn]

Shuffle pins. Clamping the case harder will only distort the main line bore

[dcpuddy]

When I had my case machined I spoke to the folks at Ollie's and they said shuffle pins were not necessary (and that the twin plug race motor he just built was not shuffle pinned). I put case savers everywhere of course.

I haven't heard of the line bore distorting with APR or similar through bolts but I'll do some deeper research.

[Flat6pac]

Through bolts, I don’t know what some aftermarket entity is doing to improve on through bolts that torque to 25 ft#.
That much concern, do SC/Carrera through bolts and nuts with their fine threads for better adjustment.
Bruce

[Henry Schmidt]

Although I feel that case through bolt upgrades is basically a luxury that offers very little stability improvements, we have used 3.0 and later (75-89 turbo, 3.0 SC 79-83 and Carerra 84-89) through bolts.
They are a slight improvement given there slightly larger root diameter and fine thread nuts. This is an upgrade that makes sense if budget is important.
Cool titanium hardware is sexy but not very cost effective. A better place to spend money on a magnesium case is shuffle pins.
Main bearing web distortion is an issue no matter what hardware is used. The key to keeping a mag cased engine survive is controlling the oil temperature.
Magnesium expands with heat and excessive heat creates unexceptionable expansion/distortion.

[Neil Harvey]

As one of many parts we developed for the Metzger engine, are the Through bolts. Actually not new as the earlier race engines used to use these. We just improved on them.

More clamping does not distort the case main housing as much as discussed here. In fact, the later race engines have torque number almost double of what is suggested here. I wonder how many have actually tested this. We have and found even with mag cases, the main housing bore does not change that much if any when the through bolt torque is increased. Lack of mechanical locking, along with elevated temperatures must have an effect. If the case halves are held together, much of this is mitigated.

It's the crank flopping around at speed that does the damage. This is why the housing bore is always out of round the closer you get to the #8 bore. Cranks twist and move due to compression forces. The front of the crank that is basically unsupported moves the most.

These engine cases have two dowels at the rear and nothing at the front. The #8 sleeve adds nothing for support. It moves independent to the case.

Evidence of the case shifting has been around for years. The bearing shells and housing bore show this on every disassembly. It gets worse as the engine displacement is increased. The longer stroke and larger bore engines really push this issue. Longer arm swings, more mass changing directions along with increased piston speeds act upon the case.

The addition of the solid dowels has been done for years. They have their own issues. Disassembly is a little more difficult and some misalignment after machining can result requiring re machining of the housing bore.

When we were asked to build some of these high end air cooled engines we knew we had to look at this issues. Holding the case together and limiting the crank movement were two important areas we looked at. With stokes upwards of +80mm and bores out to 104.00mm we knew we had to address these. The addition of the Crankshaft Damper and holding the case halves with the through bolts are the results to date.

Weight is important so we decided to make the Through bolts, Washers and Nuts in Titanium and coat the parts with DLC.

We developed two lengths of bolts, one for engine cases up to 1989 and another for cases up to and including the first of the 991 GT3 race engines. The downside is, additional machine work is required. We include the two studs at the #1 housing. And, these parts are expensive.

Do engines "survive" without dowels. The answer has to be yes. So why do it? As a professional engine company, we owe it to our customers to give them the very best engine we can. If we see a problem its our professional duty to solve it.

[dcpuddy]

Originally Posted by Neil Harvey

We developed two lengths of bolts, one for engine cases up to 1989 and another for cases up to and including the first of the 991 GT3 race engines.

Appreciate all the thoughts here, Neil. In a past life I worked in the aerospace industry finish machining close tolerance parts for aircraft. That hardware of yours is gorgeous. If I had unlimited funds I'd send the case back out to be machined again to accept those.

Originally Posted by Henry Schmidt

we have used 3.0 and later (75-89 turbo, 3.0 SC 79-83 and Carerra 84-89) through bolts.
They are a slight improvement given there slightly larger root diameter and fine thread nuts. This is an upgrade that makes sense if budget is important.

Given I'm ready to begin assembly otherwise, I'll look into the 3.0 and later through bolts Henry mentioned (thanks Henry).

[Neil Harvey]

Understood.

My post was more about the engineering aspect of holding the case together. I showed what we have done to achieve this, with pictures.

Our parts are not for all as the costs are higher. We are in the Rolex business not the Timex. Our parts follow the same philosophy as our approach to building engines.

The other parts suggested by Henry will work as have for years in other engines. We just needed to solve a problem, they will not.

[dcpuddy]

Fully understood. I have a massive amount of respect and appreciation for that level of craftsmanship.

[BartdeBruijn]

Gentlemen guru’s,

Now the discussion touches upon main bearing web deformation I have a question on something I encountered during my engine build that I just started.
It will be small spigot mag 7R case, shuffle pinned, allign bored. MFI, 85 mm high(er) compression JE pistons, modS cams etc. Very similar to the engine that Henry Schmidt describes a few times and that he build a few times too.

Anyway, I also posted here my issues with oil clearances of the main bearings before.
What I found concequently that if I torqued down my case(in two steps), without the bearing shells mounted to perform a measurement with a bore gauge and similar temp conditions that my measurements of the crank bores were decreasing for the first few days with approxemately 0.005 mm (dia) per day.
I was wondering if the bearing shells, who are despite there coting made from steel would prevent this behavior because of their domed shape…..
Maybe a wild crazy guess, however I do not know if anyone ever measured the bore dia over a few days!?

Just curious?

Best,
Bart

[dcpuddy]

For anyone interested in hearing how the story turned out, the price difference between the ARP through bolt kit and piecing together a 930 through bolt kit is only around $150, so not massive (all things considered when you start adding up everything).

That said, I called Pelican this afternoon and spoke to Kenny who is awesome and helped me place an order for a 930 kit.

[Magyar Kiwi]

Hi Bart
The link below discusses bearing crush, clearance and housing bore displacement.
When steel backed shells are installed in a magnesium crankcase the housing bore displacement will be significant and will add to the final bearing to crankshaft clearance.
Measurements to calculate bearing clearance must be made with the shells installed in the crankcase or conrod to account for the additional clearance from bearing crush and bore displacement.
I'm not surprised at the dimension changes you found over several days, the magnesium crankcase needs the support provided by the crushing of the steel backed bearing shells.
https://enginepro.com/bearing-crush-and-vertical-clearance/
Best regards

[BartdeBruijn]

Hi Magyar,

Interesting article and underlines my now, not so crazy findings!

Cheers,
Bart