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  #16  
Old December 15th 2002, 23:49
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Massive Type IV Massive Type IV is offline
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yes, more or less it is the stock cam......We have a great stock engine, but why spend the same amount of time making it stock when you can build it to a more efficient 2056,have more power and etc for the same price???The temps run the same and the engine lasts just the same no matter what.
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  #17  
Old December 16th 2002, 05:10
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Oliver Knuf Oliver Knuf is offline
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...

Trying to build up the 100% all-purpose engine is hard. If you wish to run 200kmiles, you want something, that even Porsche never did (ok, maybe 80year old grandpa drove only 55mph straight for 30 years, but even then...)! My tips for such an engine would be....

Some words to the cam. The profile, that a German GB 2,0l 100HP 914 engine has, is a 272° cam (or US ~252°) with 106° spread, 10,9mm Valve lift (8,3mm cam lift), 2,8mm lift at TDC and a wide powerband for an original engine, that lets you rev up to 6000rpm with a good overhauled valve train. It's a good cam, that can run very well with the d-jetronic.
I would blueprint all the internals, resurface the flywheel, balance flaywheel together with pressure plate crank and gears and keys. Trick item here for me would be a very reliable and powerful Fichtel & Sachs pressure plate with an aluminum race ring, as it is nearly 2kg lighter and is totally stock in optics. You don't have to machine your flywheel. Another trick item would be a set of 57gram Witzemann lifters, as they are in stock size, look like a Type 4, but are pretty light. Together with slightly tapered pushrods, equal weight intake and exhaust rockers on straight mounted shafts (without wobby shims), together with lightened original valves ot 7mm stem valves from Schrick, a good and reliable conversion. Machining the c/chamber to a better form is hard, but possible. More sense would make 100% exact volumes. Most important for me is a totally straight case, where the main bore sits super straight and the deck heights are totally the same. Only a good machine shop can do that in real high quality. Then you can be absolutely sure to have the same c/r no all 4 cylinders and having correctly angled rods in your engine.
At least I would prefer the combination with Type 1 pistons in 94mm bore (B-type for 82mm lift) as they are approx. 120g lighter than the 914 units, are "press"-forged and dissipate the heat pretty fast.
Are there restrictions on the seat machining? First, start with new seats, bigger outside diameter. The originals tend to fall out, as they were pressed in with not enough oversize by factory!
There's a lot of power in machining the seats more "racey", e.g. radius the angles to the port and to the chamber, seat width only as large as needed etc.! Exhaust port matching to the exchangers, machining the exchangers to a straight and oval surface, maybe fitting an old 911 muffler to your 914, as the mufflers are interchangeable from the old models.
Running a small (Schadek) drysump pump is a must, as the hp and reliablility gain is worth the lost power of getting the larger gears turned. Even the cooling with the original, stock cooler is better then (having 8-12 Liter in your sump system helps :-) and maybe some harder or underlayed pressure-springs are the way to receive a more constant oil pressure under all conditions.
At least, measuring, measuring, measuring... is the most important thing you can do to obtain a 100% engine.

If I would give a quote... a German GB engine, that has original 100bhp at 4600rpm would produce with these goodies a minimum of 15ponies more with extended reliability!
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  #18  
Old December 16th 2002, 14:49
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Mueller writ:
>Hope no offense Jake, this is your forum after all<

Actually this is everyones forum. In the R.A.T. area that could be said, but not in the general engine questions area.

So say whatever you want this should be a place for debate. Please post freely.

... Granted of course everyone should be nice to each other. But disagreement on issues is a good way to learn and undestand different outlooks on engines and their building.
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  #19  
Old December 16th 2002, 14:54
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Very interesting post Oliver.

>At least I would prefer the combination with Type 1 pistons in 94mm bore (B-type for 82mm lift) as they are approx. 120g lighter than the 914 units, are "press"-forged and dissipate the heat pretty fast.<

I am sure the LN Nickies could be bored for it.

DD, would this pass "tech inspection"?
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  #20  
Old December 16th 2002, 15:18
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One or two things seem to have gotten lost from this thread...

First, the primary purpose of this engine would be to last and last and last through driving conditions that are the next-best thing to intentional abuse that I can think of. Power is of secondary or even lesser importance.

Second, I am not really interested in "things you can't tell are cheating". It doesn't matter if nobody else can tell, I would know and I wouldn't like it.


OK, and now a few responses to specific notes:

Charles, I know that it's not a problem to get pistons and cylinders of just about any size from you guys--my reply was to the idea of buying the spare set of 96es you had lying around. (Wish I could, but...)


Mueller, you may be able to take advantage of the manifold that Charles N. described. It might be very interesting to have a discussion with him and Shad about it... Also note that you can actually raise compression up to 8.1:1, since you're allowed a half-point over stock. It's just a tenth, but hey...

If I wind up with this kind of motor, I will probably just have someone (most likely Jake) just plain build it. I can supply core heads, and if he asks I can get a lot of the new parts (nice to have connections, yeah?) but I'll let the builder choose the exact parts. And have whatever profit there is from them--that is often part of making enough money to put food on the table... I've found that bringing in your own parts is a decent way to sour the relationship between you and your mechanic. Thanks for the offer, though!!


Tom, the rockers are not specified. However, I am certain that rockers with ratios that are significantly different from 1.3:1 (the nominal stock figure) are disallowed. I can see lighter rockers as a reliability improvement as long as I use the stock cam--because an engine with the stock cam is worthless above about 5200 RPM--but ones with a bigger ratio are a performance improvement and are a no-no.

Perhaps roller rockers might be worthwhile to cut down on wear? Or maybe not...


Jake, I agree that what I'm asking is non-trivial. That's why I'm not just slapping a motor together at home as we speak. And, at least from what I've read from you, the stock cam and stock low compression ratio are two of the larger problems with reliability. (And quite possibly the D-jet FI, too.)

But it's in Da Rules. A 2056 with carbs and a nice cam would instantly put me into a class where a lot of not-so-nice things will happen. First, I will have to have a full cage put in. Second, all of the other cars on the track with me will have huge fat tires (possibly real slicks?), suspensions with a lot of development in them, fully-braced structures, large 911 brakes, and so on. The ones that don't serve as "rolling chicanes" will have motors up to (I think) 3.0 liters of displacement. I think I would be in with the modified Sixes, also--not quite sure on that. A the very least, I'd be in with "#22", Newlin's 1400-lb semi-tube-frame car.

Uhhh, no thanks. I want a car I can drive to work, take off early, drive up to Thunder Hill, then spend the weekend flogging mercilessly. And I want my driving to be the limiting factor, not the car--I want a car that, on its own merits, has a chance. (I'm sure I won't for a good while, but part of the reason to do this is to get better.) And having a car that gives away 100+ HP and 200+ lbs, not to mention suspension and tires and brakes, in order to remain a street car, is not going to work for me. Not to mention having to pick up a trailer and tow vehicle because I can't legally drive on the streets. (Smog-O-Rama.) So that's the "why".


Oliver, I do know of at least one 2.0 914 motor that ran for 250,000 miles before it was rebuilt. I don't know how it was driven, but the owner did claim that he took it to the red-line from time to time. He certainly is the exception, though.

My 1980-vintage Porsche parts manual only lists one cam for all of the 914 motors, including the GB code ones. There used to be a web page (I wish I had saved the info from it!!) by Hugo from the Netherlands that had valve opening and closing points for three or four different "stock" cams that had been originally used over the years, and noted that they had all been superceded by one cam grind. (I don't think he counted the cams that were used in the later Vanagons with hydraulic lifters.) So your GB-spec cam is news to me.

The GB-spec motor also uses pistons that give it 8.0:1 compression. I must keep 7.6:1 compression.

(BTW, the Porsche manuals show the GB making 100 DIN HP at 5000 RPM, not 4500.)

Balancing all of the rotating parts, both statically and dynamically, is assumed. The balance might be to a tighter tolerance than under ordinary circumstances... (1 gram? Less?) Ditto the deck heights, chamber volumes, and compression ratios for all of the cylinders. I would think they would be set up on any reasonable rebuild, but that perhaps this sort of build would be to tighter tolerances.

I am still not sure about using lifters and pistons that are significantly lighter than stock. In particular, having lightweight pistons would make for an engine that revs more freely, the same way a light flywheel does. The lightened flywheel is only allowed in the next class up (the one Mueller is shooting for) and I believe that the lighter pistons would fall into the same category. Which is a shame because they would definitely reduce the stresses on the rods and crank...

Seat machining, at least in terms of making sure the suckers stay put in the head, should be free. But a five-angle or venturi grind on the seats is going to be a no-no.

The 911 mufflers that I've seen do not mate to the 914 heat exchangers, unless I swap to the really awful 75-76 ones. (The ones that make a tight 180-degree bend near the heads.) The 911 mufflers have two inlets for single pipes; the 914 mufflers have twin pipes going into each of two flanges. I figure a Bursch muffler setup or perhaps Triad (from Washington state) would be the way to go on that.

I had not considered a dry-sump setup. That is worth considering, as an alternative to the Accusump. I could run into problems with that if it does free up extra power. (I have heard that it takes more power to run than you gain from not having a wet sump.) Thanks to you and to Yilon for suggesting it.


Thanks for the replies!! I'm still trying to wrap my brain around this all...

--DD
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  #21  
Old December 16th 2002, 17:15
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Perhaps roller rockers might be worthwhile to cut down on wear? Or maybe not...

Dave, I can't see why not. Also, are 911 adjusters allowed? I would run those just to make sure your valve adjustments are spot on.

Also, maybe adding some oiling to the heads. Shad, Jake, and I talked about this, I don't think it went anywhere (too much on everyone's plate???).

Adding some kind of oiling system to the heads could help keep temps down. Think of plumping off the end of the main bearing oil feed (it's on the driver's side of the motor, near the fan housing (now, thats for you 914 folks). Tap off of that, run a "T" and then install some squirters into the valve covers. You could be running cool oil right on the top of the head and maybe get some cooling out of it. It would return to the sump via the pushrod tubes.

Not much of a HP added, but longevity (which is what you want!)

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  #22  
Old December 16th 2002, 18:19
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We plumbed Shad's engine with lines going to the valve covers and we actually made all the tooling and programming for the billet valve covers, complete with the rifle bore to plumb oil to squirters aimed at the valves.

We held off on the project because they would be pricy, not to mention the aluminum will draw up some extra heat compared to stock valve covers. Our new heads will have an oiling provision to improve cooling and oiling of the valves, springs, guides, etc.

If there really is enough interest, I guess we could make a few sets for those interested, considering we have a huge stock of extruded aluminum billets to make the valve covers out of.

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  #23  
Old December 17th 2002, 01:53
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Ok Dave, I went and read the Zone 7 rulebook just to see what you could do. Not much really, except to use higher quality parts.
So, go with the nickies that alone should really help when you run autox to keep things cooler.
Blueprint this baby like a race motor where everything is as close to perfect as possible.
As for the Djet, the go to a dyno shop and tune the MPS to run at the right A/F mixtures at partload and WOT under load.
Before I did this my oil temps would skyrocket to 240 degrees during runs. I share my car with my son so we go eight times! After tuning the MPS I stay under 210 degrees on a 80' day.
A 200,000 mile engine, well I don't think the heads/valve guides were ever designed to last that long (heads 100k maybe). But the rest can especially with the nickies. There are several cars I have seen that were into the 160k range that ran really nice, of course they had been maintained. Sadly, most 914 haven't as you well know.
Cost, probably into the $5000 range with the nickies.....
Using Megasquirt might be the answer the the FI problems and squeeze some extra hp out of a motor at high rpm.
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  #24  
Old December 17th 2002, 04:19
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....

Can we find the race rules anywhere in the net?
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  #25  
Old December 17th 2002, 10:01
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Oliver,

The PCA rulebook can be found online at http://www.pca.org/pca/clubrace/docs/forms.htm

Charles Navarro
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  #26  
Old December 17th 2002, 14:40
Dave_Darling Dave_Darling is offline
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The roller rockers sound like an interesting possibility. 911 adjusters are a definite "yes". Spraybars in the rocker box sound interesting, but a really serious PITA. Worth consideration, though!

One problem with the Porsche club(s) is that there is no one set of rules for anything. The Club Race people use one set of rules for their wheel-to-wheel stuff. If I were ambitious, I could make three or possibly four Club Races per year by driving for up to 8 or 12 hours each way. Zone 7 (N. Cal. and a bit of Nev.) uses another set of rules for its time trial and autoX series. Zone 8 (S. Cal.) uses a third set. The Parade autocross (Parade is the national PCA convention) uses a fourth set of rules. The Porsche Owner's Club, who do a lot of big-track stuff, use a fifth set.

Any similarities between any of these sets of rules is purely coincidental.

The rules I am trying to follow are here: http://www.pca-ggr.org/ggrrulebook.html
The classification rules are here: http://www.pca-ggr.org/ggrrulebook.html#_Toc532905425

The class is B-Improved.

--DD
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  #27  
Old December 17th 2002, 14:49
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As long as those rockers are self oilers they are good for reliability...Pauters are NOT self oilers and will NOT work with 80% of cams on the market,including some of the ones that Pauter even makes to go with them!
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  #28  
Old December 19th 2002, 12:44
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Some interesring points....

Some interesting points in the rule book for stock category are:

Cam Timing: Any cam timing may be used

Cooling: Any oil-, water-, or air-cooling change, which allows the engine to run cooler, is permitted, unless otherwise prohibited. The 914 plastic engine cover water tray may be removed. Such changes tend to extend engine life and should be encouraged

Fuel Pump: Any fuel pump may be used. Fuel pumps should not be a problem. If, in a specific case, the fuel pump is a limiting factor, the driver should be allowed to correct the problem

Balancing: The motor may be balanced. Note that this is not necessarily a recommended procedure. Most Porsche engines are built so precisely that they will not achieve any noticeable performance increase through balancing

Motor Re-builds: To allow for normal rebuilds, the motor may be over bored to a maximum of .5mm. Note: to remain in the Stock or Improved Category, any motor, which is rebuilt, must retain the stock compression ratio. If any procedures (such as truing the heads) change the compression ratio, cylinder spacers or other parts and/or techniques must be used to bring the motor back to stock compression ratio

Adjustments: Except as noted, any modifications for the sole purpose of facilitating adjustment of the car or the motor (such as modified valve adjusters) are permitted

Non-Performance Modifications: Any modification that is clearly not related to performance is permitted

Ok, I would use a 911 cooling system, maybe horizontal mounted with an external oil cooler and modified intake runners, but stock intake diameters. Just an idea. I would use a modern cam, that produces more hp, as most modern cams can produce more hp than the stock unit. Use the lightest stock parts, like the 8mm rockers with swivel foot on straight mounted shafts, use 94,5mm bore original Kolbenschmidt (as this is the rule), use a fuel regulator instead of the original non-regulating fule pressure holder. Redisigning of the C/C is helpful, as you can design it to modern aspects. If you would have a European engine sheet, why not updating the engine to a European config engine? If you can run a European engine, it would be very helpful!
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  #29  
Old December 31st 2002, 15:48
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Re: Some interesring points....

Quote:
Originally posted by Oliver Knuf
Ok, I would use a 911 cooling system, maybe horizontal mounted with an external oil cooler and modified intake runners, but stock intake diameters. Just an idea. I would use a modern cam, that produces more hp, as most modern cams can produce more hp than the stock unit. Use the lightest stock parts, like the 8mm rockers with swivel foot on straight mounted shafts, use 94,5mm bore original Kolbenschmidt (as this is the rule), use a fuel regulator instead of the original non-regulating fule pressure holder. Redisigning of the C/C is helpful, as you can design it to modern aspects. If you would have a European engine sheet, why not updating the engine to a European config engine? If you can run a European engine, it would be very helpful!
Changing the cam grind is not allowed. I'm not sure how else a "modern cam" could produce more HP than stock, other than by having a different grind. The cam, due in large part to the experience of the folks over on the Shoptalk BBS, would be Web-Cam's stock grind.

When you say "fuel regulator", do you mean a fuel pressure regulator that is referenced to manifold vacuum? (The stock one maintains a constant pressure.) This would require tweaking the FI parts to correct the mixture, but that can be done.

I cannot redesign the combustion chamber--porting the heads is not allowed. Polishing them to eliminate "hot spots" is arguable, and would be done if it were worthwhile for that.

I'm also not sure what you mean by "European engine sheet". The rules, as written, apply to stock US-spec 914s (that's what you can start modifying from). The GB-code engines had an 8.0:1 compression ratio, which is not allowed in the class I wish to run, so I cannot use a European-spec motor.

--DD
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  #30  
Old December 31st 2002, 15:55
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I'm sorry, but this race class makes zero sense to me......None.

They are forcing you to race with an inefficient engine, and won't even allow a cam change???

I'll almost GUARANTEE you that 90% of the participants are cheating if you were to tear them down....

You know what they say, if you are cheating and "They" are not you are wrong, but if they are cheating and you are not you are just dumb........

Just my outlook..
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