Ultra-reliable "stock" engine?

[Dave_Darling]

I've been toying with this idea for a while. Months, actually... The note is partly thinking out loud, partly asking opinions of Jake, and partly asking opinions of anyone else who wants to chime in.


I have a 2.0L 914. My local PCA (Zone 7) rules have a particular class that I want to run in. In this class, the engine has to stay stock in most large respects. However, modifications that are specifically for the purpose of increasing the reliability of the engine are explicitly allowed. ("Methods of ensuring oil flow" and "external oil coolers" are listed as two examples.) So I am trying to come up with ideas for a motor that would be prepared to the limit of the rules.

The purpose of this motor would be to go as far as possible between overhauls--even just re-lapping the valves--while keeping stock or better power. (95 HP DIN.) The engine would see all manner of use, from daily-driving in the city, to 4-hour freeway trips (probably running 4000 RPM in top gear), to 20- to 30-minute lapping sessions which are almost constantly at WOT from 4200-5000 RPM. All of these in air temps ranging from about 30 degrees (very rarely) up to 110 degrees.

Restrictions:
Stock-grind cam
7.6:1 compression ratio
Max. 94.5mm bore (allowed 0.5mm over stock)
71mm stroke
Stock size valves
Must run D-jetronic fuel injection
Must use 914 heat exchangers and a muffler of some kind; SSI exchangers are OK
Stock distributor (points replacement and/or CDI is allowed)
No porting of the heads, though if that were somehow only done for reliability that might possibly be allowed
Stock cooling system
...And for my own personal convenience, it must also be able to pass current California smog tests. (It won't go exempt until 2004. And I'm not completely confident that the jokers in my legislature won't change that again soon!!)

From reading on the Shoptalk Forums, it seems that Jake believes that using the stock cam, stock compression, and D-jet FI are very good ways to heat the heads up until you run into problems. I have dropped three intake seats (mostly due to mixture problems I think) so far, so I am worried about overheating the heads. But those are the rules I run under...

I had been thinking to run LN Birals in the stock size initially. But the prices of the production Birals came out somewhat higher than I had been anticipating, and it seems the step up to Nickies might actually be something I could stomach. It is my hope that using cylinders with superior cooling properties would help on the head temperature front. I was also considering some kind of coating on select parts of the heads...

Since 914s, particularly on "sticky" tires, can generate significant lateral G forces, I need to address the oiling issue. I have been using the Weltmeister Oil Trap, AKA "the tuna can", which is a small sump extension with an oil pickup extension. It has proven OK so far, and it does not seem to be in much danger of hitting anything. But Jake disapproves, and I can see that I might be very unhappy if I go over the rumble strips a little too enthusiastically and rip the thing off. So a less-vulnerable method may be in order, like an Accusump. I figure a 1-quart (or whatever the smallest size they make) would be more than adequate.

What other oil system modifications would be in order? An external oil cooler is often recommended for time-trial cars (20-30 minute run sessions at Wide Open Throttle, 4000-5000 RPM the whole time). Would it still be necessary with the other mods mentioned? Would it be a better idea to block off the stock cooler location and only run the external cooler? If an external cooler is recommended/required, would a large fan-equipped cooler in an area with mediocre air flow that is heated by the exhaust being below it be good enough, or would a cooler with lots of cold air flow be required?

Would other coatings be recommended? Cryogenics or heat treatment? I am still, quite frankly, rather skeptical of most of the claims made for cryo treatment (my research has turned up quite a few people on each side of the debate) but I am willing to give it a try if it really will help.

Stock valves or aftermarket? They must be the stock sizes, of course, but whose?

Will having a lightweight valve train help the engine be more reliable? I can see how it could help if I miss a shift and over-rev the motor (to a limited extent, at least) but is there any point with the stock mild-mild-mild cam?

Would tightening up the deck, while still maintaining the 7.6:1 CR, be worthwhile from either a reliability or a power standpoint?

Pretty obviously I would want to use the 911 swivel-foot valve adjusters, have all of the moving bits balanced, and so on.

And finally, of course, is the question of money. Nickies will cost--yes indeed they will!! And all of the other detail work (balancing, CC'ing, 911 valve adjusters, match-porting the oil pump, etc., etc., etc.) all takes time which means money. I wonder what kind of ballpark all the above would land me in?

Thanks for any thoughts on the above!!

--DD

[Yilon]

Dave:
I myself ALWAYS ran strictly within the rules. HOWEVER, there were a lot of no-good cheaters I ran against.

Stock-grind cam: Do they mean STOCK cam or stock lift and duration? (The faster you get to max lift, the more power. If they do not do visual checks, chat up a cam grinder!)
7.6:1 compression ratio: If they mean stock combustion chamber CCs, a clever man can play with deck heights to great advantage.
Max. 94.5mm bore (allowed 0.5mm over stock)
Stock size valves: normally means stock valve head size. Some clever guys do machine work to lighten the stems. The rest of the valve train needs to be as light as practical. A good man with a grinder can do quite a bit of good here.
Must run D-jetronic fuel injection: Do they restrict throttle body size?
Must use 914 heat exchangers and a muffler of some kind: Think sttraight through here.
Stock distributor (points replacement and/or CDI is allowed): CDI is the only way to go with (of course) the matching coil sold by the CDI manufacturor.
No porting of the heads, though if that were somehow only done for reliability that might possibly be allowed. In a place long ago and far away certain people found that a clever man could port a head and then acid etch the head to make it look as if no porting had ever been done. (I mention this only so that you can detect cheaters, of course.)
Stock cooling system: If they allow 'power pulleys,' some advantage might be gained here. My own 'power pulleys' always were degree etched to aid tune ups. (No one ever seens to check the diameter of a degree etched pully.)
...And for my own personal convenience, it must also be able to pass current California smog tests. (It won't go exempt until 2004. And I'm not completely confident that the jokers in my legislature won't change that again soon!!): The nice thing about FI is that the metering sizes can be easily chaged to lean the engine down to 'pass' as long as the engine is never driven hard with the lean settings. The valve lash can be set to about TRIPLE the recommended, again as long as the engine is never driven hard.
The heads can be modified to prevent dropped seats; this is a reliability issue.
If I had the bucks, I would try to go dry sum, for reliability of course.
And the final step, for reliability of course, is blueprinting and balancing.

Is this all the tricks? This is not even the whole first chapter. However it is the first few faltering steps for a fellow GermanLook guy.

[Powerman]

Dave, I would go with an Accusump for the oil starvation problem.

[Wally]

Dave,
As a tech geek, you will probably have thought of this, but lightening the flywheel (to about 5.2 kg's) will help spinning the revs up quicker. So will ligthening and polishing the standard rods with about 120 grams each. This is done overhere by BAS and would not decrease strength, so I was told.
Good luck,
Walter

[Dave_Darling]

First, let me say that I had a nice long reply written earlier but my browser ate it.

Second, my intent isn't to "get around" the rules (i.e., sandblasted port work looks like no port work) but to stretch them just a little.

But the main goal really is reliability. I would like to see rather over 100,000 miles of abuse on this motor before I have to pull the heads off. Hopefully 200K or even more!

When I say "stock", I do mean stock. I can't monkey with the lift/duration of the cam, or even how rapidly it gets to full lift (I think that could compromise reliability anyway), and so on.

Sadly, the flywheel falls into what I cannot do. I can't even really lighten the reciprocating/rotating bits at all, except in the interest of reliability and balancing. (But no, taking 50g off each of the rods for "balancing" is very definitely a no-no.)

So the question remains--what can I do to ensure the maximum of reliability out of a basically stock engine that sees a lot of hard use? ... I do hope Jake chimes in on this one, even though it has been moved outside of his vendor-specific forum...

--DD

[ShApE]

i would lighten the flywheel it quickens ur revs but but lowers ur top speed

[BergRace]

Originally posted by ShApE
i would lighten the flywheel it quickens ur revs but but lowers ur top speed

"lowers your top speed" Think not!!

[kdanie]

Dave, You hit all the things I could think of.....Jake says cryo helps aluminum disipate heat, Cryo the heads, heck, cryo the whole engine. Coat the piston tops, valves and combustion chambers (I think I would do the exhaust port also) with ceramic metalic coating to keep the heat in the combustion process and out of the heads/oil. Coat the iron cylinders and exterior of the heads with a heat sheading coating to blow off more heat. Use stock size Manley valves with undercut 8mm stems, especially on the exhaust (they will build custom sizes at reasonable prices if they don't stock what you need). Stock sodium filled valves are heavy, tend to fail (according to Jake) and have huge stems. Full flow the case (search the STF for pictures or talk to Jake), use remote oil cooler with fan, remote oil filter (the stock filter mount has several sharp corners in the oil passages) and an Acusump. Run a tight deck like .035", better quench=more complete burn=more power (you are not reving real high so .035" should be ok). Coat the piston skirt, cam, cam gears, rocker shafts, oil pump with dry film lubricant (less wear and friction). Use some ARP rod bolts. I would also run forged pistons too but that's just me. Light weight valve train always helps reliability, it is better to run light weight parts rather than more spring pressue (lighter springs also free up power). For the coatings I would go to MicrCoat in Santa Rosa CA (north bay) and talk to Bruce Corneto, phone #(707) 578-4010, he's a one man shop so you may need to leave a message if he is busy.
ken

[cnavarro]

Our Nickies would most definately make it "ultra-reliable"-- no doubt there. We have some smaller bore type 4 Nickies left over from our last run that i'd be happy to wheel and deal on :-) We could set you up with some 96's and you could save some money by using Keith Black 96's...just a thought.

I'm in the process of building up my 2320 and i've gone all out and had the heads coated with a thermal dispersant and I have had the exhaust ports ceramic coated as well, as was suggested in another post. The dry film lubricant idea is an excellent one as well for the gears and even the bearings. You could go so far as coat the rods and crank with oil shedding coatings. I've looked into Calico Coatings myself; their site can be found at http://www.calicocoatings.com/ . You could most definately opt for the cryo'ing. Coating the piston tops is a mixed bag-- you'll increase the thermal efficiency but decrease the volumetric efficiency, sacrificing about 1 horsepower for a little better fuel economy. I'd personally spend the money on coating the piston skirts to reduce friction, but that might be overkill with nikasil.

One thing to ask the rulebook- do you have to use the stock intake runners and plenum, or can you swap in a different one. Our estimates show our intake should be a bolt-on 11HP with the stock d-jet on a 2.0L. Worth a try :-)

Take care,

Charles Navarro
LN Engineering
http://www.LNengineering.com

[Dave_Darling]

Jeesus! 11 HP more out of D-jet? Or your plenum will support flow up to another 11 HP? There's a difference between the motor and intake being able to flow that much air, and the complete engine (the whole system, FI and exhaust too) being able to provide it.

11 HP is a whole lot!

Sadly, I am restricted to stock manifolds and throttle body size.

I am also restricted to 94.5mm bore, so the 96es won't do me much good.

Hmm, piston squirters? Might not be worthwhile, but then again...

--DD

[BergRace]

"Coating the piston tops is a mixed bag-- you'll increase the thermal efficiency but decrease the volumetric efficiency, sacrificing about 1 horsepower for a little better fuel economy"

Could you elaborate on this please?

Thanx.

[cnavarro]

I am also restricted to 94.5mm bore, so the 96es won't do me much good.

We can make as small as a 91mm bore, fyi, out of the same blank, so 94.5 is no problem at all :-)

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

[Massive Type IV]

The engine you desire is VERY tough to make happen. For it to encompass all the things you desire, including passing California smog,being trackable,being reliable.

The class rules limit you to many things that create inefficiency, and unreliability (in my opinion)

with an engine like this, al the power and reliability must be "fluffed and buffed" into the engine. The Blueprint process means alot,as does the enhancement of the "squish",which is limited as well because you must keep the engine to 7.6:1


This is very unstable ground to base an engine from, and honestly it scares me away due to having to pass the emissions testing and etc. The 100% stock engine is inefficient.

[Mueller]

Jake, why do you say the stock motor scares you?

It's been proven to work for almost 30 years? Sure it's not the most effiecient package, but it works without a doubt, there are or were I'd say thousands of 914's going strong as built by the factory for years and years.

Had the owners taken proper care of these powerplants, I'm sure many more would be alive today (the motors and cars that is)

Dave is not asking for a specific HP level, he just wants something to run for a long time and not scatter a few years down the road. His layout for parts and ideas seems just about ideal and he should be able to obtain at a mininum stock HP leves if not a few more percent.

I am building my motor just about the same way as DD wants except I'm going for one class higher that allows me to run the Euro P/C's, so I am. [would that make me have more class than DD?, LOL]

Did you mention balancing the rotating assembly Dave?

Hey Dave, I have all new stock sized SST valves, retainers, springs, lash caps that I am not going to use since I picked up a set of freshly rebuilt heads from Jon Watts, I'll make you a good deal if you want them. Besides, after the 911 crash, I might have a 3.6 motor at my disposal

I do wish I had done the piston squirters, [this is something Capt Crusty did not disaprove of believe it or not] but you'll need an external cooler to get rid of the extra heat that is now in the oil.

Hope no offense Jake, this is your forum after all

[Tom Perso]

I think there is one hangup with this whole deal.

The STOCK cam.

From what I've heard, the stock cam retains heat in the combustion chamber for faster heatup and better emissions.

Good for passing the sniffer test but not much else.

Dave, what about rockers? Still stock?

Later,
Tom