The alternative to Viagra...Henry's motorshttp://forums.pelicanparts.com/support/smileys/pray.gif

Someone please sell me a case so I can get my own 2.8SS porn....

We'd love more tricks like these.

Now here's food for thought: When chevy heads build a 325, 352, or 377, they take a 400 block (large journal) and use extra thick bearings, or bearing spacers (big no,no) with a 302, 327, or 350 crank; would this be possible in a Porsche as the SC case can be thought of as a 400 block and the 2.2s crank can be thought as a 302 crank.

Mac

Yes and no. All the main journals except #1 are the same on the 66mm and 70.4mm cranks. The 1978 and on 930 (includes SC) cases have the same journals. Only difference is #1, which has a wider crank journal (facilitated the switch to the 9 bolt SC and later flywheel) and hence a wider hole in the later case for the wider crank journal and bearing. But I've talked with a guy who just made some kind of spacer so a regular SC case would be run with a 6 bolt 66mm crank. He must be a pretty good machinist. I see no advantage to this other than the fact that it lets you use the relatively common SC/3.2 case rather than the rare 930 cases from '75-77.

Walt Fricke

Pretty big advantage.

Do you perhaps know the guy's name or business name? This would be a great product to market.

Mac

I can't quite remember. It might have been Pat Williams (patwilliamsracing.com is always worth a look). It might have been the guy from Zuffenhaus at the Charlotte Parade. It might have been Bruce Anderson. And it might have been someone else.

I doubt there is much of a market: how much would it cost to make 100 of them, and how many would pay how much to purchase one? By and large guys like larger motors, not smaller ones. Why build a trick 2.8 when you can buy a 3.6? Simpler to make them each time a customer says can you make one of these.

The 2.8SS is a neat motor. But had I been able to predict the formula we came up with for PCA GT classification, I'd have just built a high squeeze, tricked out 3.0. Fewer special parts, and I'd not be looking at how to shed even more weight from my car, which is already pretty stripped down.

But I'm slowly forging on with my SS. To be decided: what valves to use in the 3.2 heads I have for it. After that, what cams.

Walt

New 9 bolt, 66mm cranks are coming and they will resolve all of the needs for short stroke engines. Chrome molly, modern oiling, full counter weights and more.
Countdown about 3 weeks or so.
Why just 66x95 when 66x102 is possible? 9200 rpm 3.24 ltr.? Yikes!!!!

Now you're speaking my language. Who is making them?

Disclosing some of the information about our new product before it exist seems somewhat premature. Once I have the first run in my hands and have completed the inspection and testing process, I will share all the pertinent information with everyone who's interested.
I will say that the cranks are being made with 100% certified US materials (chrome-moly) and were designed and manufactured in So. Cal.

I've had my fill of dishonest Chinese manufacturers.

Same company who have been making the 912 cranks by any chance? If so it will be a work of art!

pricing?

No 912 cranks, at this time they are only making a few special order 911 cranks.
here's the only hint you get. Their main work is with very high engines.

$3500-$4000 depending on developement work required. They will come with special main bearings required for this crank design.

great, i'll call you as soon as i win the lottery :D

Product warning: If erection lasts for more than 4 hours, step away from the computer screen!!!!
Then call Extreem Escorts @ 1(976)-too-cute

You need to re-title this thread to something other than "Short Stroke" then!

Henry, is that sound file on the Supertec site of a 2.8?

YES
This is the engine. 2.8 SS stroke 66x95, twin plug, slide valve, 9.5:1 comp street gas.


http://forums.pelicanparts.com/uploa...1227510165.jpg

Henry,

quick bump, i started hording parts, got the case, the crank, now the rest.
I'll be ordering Headstuds from you in the near future, sorry i can't order the 2.8SS direct, i'm poor, plus i like to get my hands dirty and diy a bit.

But do you happen to have a Dyno sheet from a stock 2.8SS , as you build em? Just so i can get an idea what the Benchmark looks like?

We have head studs in stock ready to ship.


As for the dyno sheets, we haven't torque tested an engine in quite a few years. We found when we had a dyno that everyone wanted a sheet but no one wanted to pay for it.
We get figures from customers upon occasion but those numbers are always subject to outside influences.
300 hp would be considered a reasonable top line and with milder street cams I would think 280 would be reasonable.
Good luck with your build.

Henry, 280HP with milder street cams?
define milder? DC60? DC40?

DC 62 with a 106 lobe center might do the trick.

Just scored a set of 3.3 turbo heads heads in the UK
port size was 38 mm , i'll have to open that up a bit, but with 49mm in, and 41 something out, in the valves department, i guess it will do , right?
They already came with twin plug and mfi injector work done, so that helps too

If you are building a 2.8SS then those ports might be OK as they are. I beleive Henry recommends 38mm intake ports for a 2.8SS to keep the port velocities fast enough. I have 3.2 heads on my 2.8 and I know Henry thinks the stock 3.2 ports are too large at a little over 40mm (I forget the exact size). Granted my motor runs great at all RPM's, but I've always wondered what it would be like with slightly smaller ports.

already got the MFI stacks bored to 40mm (bought them this way), so i guess it will have to be 40, which is what Henry described initially
won't have the lip for pulse control, and it will have more high end then low end optimisation, but i have to get to 40 or i'll have a lip in the wrong direction.
3.2 ports are 41 someting mm

Stijn,

You are correct. It has been a while since I went through this thread and I was misremembering the sizes. Sound slike you got the right heads to start working with. Have fun!

haven't decided yet, but i might end up with 97mm jugs... that would make it a 2.9 short stroke.
Not sure if that makes much difference for revability, i suppose the pistons would be a lil bit heavier...
But then i would not need to make the same revs to get the same output.which makes it easier on the valve train and gains a bit of torque while i'm in there.

Henry,

You mention using the "solid" chain tensioners in this 2.8 motor build as apposed to hydraulic chain tensioners as they never fail. I am building my first flat 6 a 3 ltr for track use high lift cam etc. Would you recommend the solid chain tensioners here and why? The motor will not see street usage and will be removed and refresher once per year.

Also what is the part number for these solid chain tensioners.

Stay tuned,

PFM

not sure there is a part number for those, my 73S had solid tensioners,
it was just a machined aluminium block, with a screw to tighten things up.

http://forums.pelicanparts.com/uploa...1261942395.jpg

And although the tensioners can't fail, they won't adjust when the chain stretches...
it was very slack when i opened up my 73S...

svandamme,

Thanks for the input and photo, I do not think the adjustment would be a big deal, it is a track car after all. I believe I have a set of those in the garage but thought of them as a tool to check cam timing with not to run in the motor. I like simple in a track motor, less oil lines simple parts less prone to fail etc. My only thought is there is zero "shock" absorption for the chains with these installed.

Stay tuned,

PFM

PFM - you hit the nail on the head, sort of. The solid tensioners only set a "correct" tension for one temperature. Colder than that and the chain will be too tight, hotter too loose.

Opinions seem somewhat divided here for race motors. But for advice based on the early 911 motors, where the stock trensioners failed more often, I'd be careful about accepting it.

Me, I run either Carrera tensioners (never failed me absent my having messed one up removing it) or the immediate pre-Carrera tensioners (narrow mount to go with the gear wheel carriers which have the wider bushings where they pivot) with collars. And at some point I will do the modification to my Carrera tensioners which limits how much they can collapse.

I have a set (milled to work with the wide gear carrier) of these mechanicals in the tool box as replacements at the track should the non-pressure feds fail. Problem with pressure feds failing is that you can't replace with something else without a spare set of chain box covers - ones without the holes for the pressure system.

Gluing a plastic cap into the hole only works for 40 minutes or so - ask me how I won our Club's Exxon Valdez award once in the best forgotten past.

Walt

Walt,

Again good info, I understand the chains would be "loose" until the motor comes up to temperature but to be honest I think stomping on the throttle of a cold motor is a bad idea anyway. http://forums.pelicanparts.com/uploa...1262058352.jpg But you gotta admit this is a very simple and bulletproof part. The oil fed tensioners have the advantage of not needing to adjust them, handle the cold motor better etc. but there are many more parts and pieces added to the mix to gain those advantages.

I am still on the fence.

PFM

Here is another thing about regular tensioners: their pressure is mostly, I believe, generated by the hefty spring inside of them. The oil serves as a shock absorber, being forced out a small orfice and elsewhere when the chain applies enough pressure to push the spring down, so the natural frequency of the idler wheel is something other than that of the spring in the tensioner. Something like that.

The pressure feed serves to keep the chamber full of oil when, for some reason, the tensioner is extended beyond whatever its most recent retraction was. The earlier tensioners did this by catching oil in the cupped top of the tensioner body, and somehow getting it inside as needed.

Someone once told me that they ran their engine without the chain box covers (or maybe just one cover) just to see what was happening. Said that surprisingly little oil flew out (unlike the experience of those who have tried this with valve covers). And that it was amazing to see how much the chain jumped around.

But I have yet to try this, much less compare a regular tensioner with a solid one.

For real security, the airplane regulators required Porsche to use gear drives for its airplane motors. I suppose those would be hard to come by.

Walt

anybody know anybody who flies one of those PFM3200 engined Mooney's?
Maybe they can come up with some part numbers, schematics, and price tag for those gear drives?


EDIT, never mind, only 80 PFM3200's ever built, no factory support... it would probably be easier trying to make em from scratch

When I rebuilt my 930 tensioners I discoverd that the spring isn't really heafty at all. When doing the rebuild you insert a steel wire trough a hole to release the check valve in the tensioner. To bleed the tensioner from any trapped air you then pump the piston a few times and you can actually do that with your thumb!
But when you remove the steel wire you need a vice to compress the piston...

These tensioners are sealed no oil gets either in or out. When they fail I guess one of the o-rings inside fails and the oil can flow "free" inside or from the inside out.

956s also used the same gear drive for the valvtrain as the PFM

http://forums.pelicanparts.com/uploa...1262116742.jpg

great, now to find a breakers yard that has a 956 on the chopping block :D

Well, there are ways... http://forums.pelicanparts.com/911-engine-rebuilding-forum/248909-rebuilding-962-motor-10.html#post2398960

OK now the 956 gear drive looks like the way to go but I believe they are out of my price range. Even if I whittled it up from billet .... Not enough hours in the year

Thanks for the post.

Yup - massive overkill. But look what those engines were built to do.

Tensioners just aren't a weak point in a race motor built by and for the likes of most of us. I had one go bad (and that was a fluke due to my bad wrenching) in 25 years of DE/racing/street amateur use. Once the idler bearing issue was addressed these should be good. And all that meant was I swapped in a spare at the track. No disaster.

How much extra money do you want to spend? Extra time fussing with adjusting to get the best compromise setting with the solid setup? Are you shooting to win a 24 hour pro race? Porsche used aluminum cam chain gears in their race motors because they expected to replace them after rather few miles/hours. Collars/pressure fed mods will insure a failure of the tensioner does not cause the chain to skip a link.

To each his own, of course.

Walt

We've been using solid tensioners in race engines and miscellaneous street engines for years with 100% success.
The key is high performance chains and experience that tells us that the distance between crank and cam centers expands at a predictable rate with heat. This means that the chains tighten as the engine heats up.
The short duration between freshen ups in race engines means that there is a limited need for maintenance and zero failures in solid tensioners.