Hello, I can remember writing about this a while ago, but thought i'd ask again as my minds a bit naff.
I have a 1600cc AB engine (with Engle 110, 1500 g/box and 32/36 Weber dual Choke). I've seen that you can buy a piston kit to make it 1641cc. Sounds good as i understand that you dont need to start having things bored out/machined.
Questions
1) Will i notice a difference in speed/BHP? will a whopping 41cc's make any difference?
2) Would it be ok with the cam shaft and existing weber.
3) should it be ok, is there anything else i would need to buy? or is everything in the kit? (kit comprises of barrels, pistons, clips and pins - ooh yes and the rings)
Money is a bit tight, so as much as i would like twin beefy webers i cant afford it (other bits needing sorting on car)
Cheers fellow bug'ers - ant UK - 1966 'Mellow Yellow' Beetle
Actually, in engineering terms it's a terrible idea. Enormously popular with the kiddies, of course.
The 85.5mm jugs in your 1600 engine started out as 83mm jugs... which began as 77mm jugs on the stone-reliable 1300 engine; all have the same spigot-bore diameter. Then the factory bored them out to make the 1500 engine. And over-bored them to make the 1600 engine, which leaks like a bitch compared to the 1300. Then the after-market people, knowing that most VW owners are about as bright as a bunch of carrots, over-bored the already too-thin 85.5's to produce the famous 'slip-in'
87's and sales boomed, since every kiddie knows bigger has to be better. Of course, the engines fitted with such junk never last last very long but that's the whole idea -- to seperate the kiddies from their cash.
.................In contrast, my 1679 with machine-in 88's still has so much compression after almost 20,000 miles that I have to struggle when trying to turn it over by hand during valve adjustments. For longevity, I'm thinking that they're pretty darn good. I wonder whether they have a wall thickness that's comparable to a 1300?
AB would have been 1300 originally. So as Bob says, its already up 2 sizes.
not 100% sure on the next bit - corrections welcomed !
Big carbs dont make any difference till you can get more air through the system (engine). i.e. bigger barrels, longer stroke, higher revs. Which means you need to plan your engine from the start as one unit, not just keep bolting things on hoping for a bit more power each time.
Even if its built well as a power engine, it wont last as long as a stock 1300, if you want to use it like a stock 1300. High power VW = high maintenance VW.
To the extreme that 'race' VW engine life is measured in minutes - not miles !
Were it not for the untimely death of Heinz Nordhoff in the spring of '68, VW might well have introduced a new, more environmentally friendly '1800' engine using a 74mm crank and 88mm jugs, which was cancelled upon his death.
One of Nordhoff's ideas -- re-introduction of a bare-bones 1300 bug -- was too far along to cancel and the record shows it's sales were far better than the bean-counters anticipated.
But with his passing, control of the firm fell into the hands of accountants and away from the 'car men' and engineers. This lead to further cheapening of the product in order to enhance short-term returns. While it looked good on paper (sales peaked in the early
1970's) the steady decline in quality and lack of a long-range plan based on sound engineering eventually drove the Sedan out of the marketplace.
Don't do it. The 1641 cylinders are weak and will square after time and lose compression. BTW an AB is a 1300, unless it has been changed to a 1600. If it is a 1300, then the heads will be a different bore, so they will need machining anyway. It's been a while, but there might be 1300 slip in 1641s, but I can't remember. Anyway, they aren't worth having either way.
My personal favourite is the 1776, as this has the thickest cylinder wall of any after market, less the 1679 (88mm) machine in, but gains the extra
100cc.
Have you read the article on the Ramva index on building a performance engine?
..............What are your thoughts on the practicality of a 88x74 type 1 with machine-in cylinders and a counter-balanced crankshaft? I understand that the heads won't allow sustained power usage past a certain level without getting too hot but I'm a lead foot and it would be nice to be able to out-accelerate those pesky SUV's & minivans. I'd like to stay with the Jetronic FI and stock exhaust system and maybe a mild aftermarket cam grind like WebCam's 118. I've never read much about a set-up like this and need some guidance :-)
bigger heads, bigger exhaust. Don't know about the FI, how to make it keep up. The stock peashooter exhaust is the worst bottleneck for any performance upgrades, and is the first to go.
..............The FI style stock exhaust flows better than the peashooter system on carbureted engines. My reason for wanting to keep it is to keep down the exhaust noise and also to keep the stock FI style heater boxes. The heads that I've already purchased are Aircooled.Net's level 3 stock VW heads which have less porting and smaller valves than the more radical level 2's &
3's. I'm thinking that 1800 cc's is probably the upper limit of what a stock Jetronic system can handle so long as I don't go past maybe 5,000 rpms but I'm just guessing about that.
.................Whoops. I meant to say that the level 2 and level 1 are more radically ported and have larger valves than the level 3 ones that I have.
The 88x74 is a very practical engine. The 74mm crank is the largest that can use stock-length connecting rods, making it less expensive -- and more reliable -- than the more popular sizes endorsed by Conventional Wisdom.
But you're comparing apples to oranges when you link the 70 year old VW design to a modern, water-cooled four-banger, some of which are not much bigger than a shoe box but can crank out an honest 140hp... and still give you a quarter-million miles of trouble-free service AND
30mpg. Tackle one of those with a bug and you've just been suckered
-- you're playing the other man's game. If you want to win you need to skew the odds in your favor, such as playing in the dirt. Take any modern vehicle off-pavement -- including most SUV's -- and all they'll see of you is tail-lights.
Studying the differences between the early Porsche and the VW will help you understand the VW's thermal limitations. It should also make it clear those limitations are inherent in the design. If you need more SUSTAINABLE horsepower you need more fin area and better exhaust valves. Of course, more fins won't fit under your tin-ware and better valves won't fit your heads. You can pull as much PEAK power out of the thing as you're willing to pay for but only for a couple of runs.
The satisfaction of dusting a suburban housewife in her minivan -- who probably doesn't even know she's just been blown-off -- will make you a member of the Engine of the Month Club, which is what all those after-market retailers are hoping for.
Time to start thinking for yourself. All those wunnerful folks trying to sell you all that kewl stuff aren't doing you any favors.
...............Thanks Bob. That's what I was hoping to hear.
...............A bug's 1800 lb curb weight with weight transfer to the driving wheels during acceleration can provide the basis for an eye-opening lesson for those @#$%^&*! Chevy Tahoes and Jeep Grand whatevers. All you need is maybe 90(?) horsepower and a short distance so that the head temp gauge stays under 400 deg while the lesson is being administered. I'm well into my fifties now and I can only pretend to be what I once was by humiliating some of these thirty year old losers who think that their $40k has bought them supremacy of the road.
...........I don't need more sustainable horsepower than is needed to propel my 1800 lb. bug down the road at about 75 mph. You've posted how much that is in the past, it's a modest number I recall. As for peak horsepower, yeah I admit that I want more than I'm getting but my wants are fairly modest. Maybe 90-100 hp with an rpm limit of 5,000(?) and a peak head temp of 400 deg F. My dad was a pilot and I know what you're supposed to do when you see that needle reach 12 o'clock on the CHT when you're running aluminum heads.
...........Oh Bob. Trust me, some of them know exactly what you've done to them and they don't like it. I've been saluted by some of the classiest looking female executives that you'd ever want to avoid at a congested on-ramp. My engine is still doing pretty good so far even though it still has a pair of Berg semi-hemi heads on it since it was built almost 20,000 miles ago. The end play is good and there's no varnish in the rocker arm galleries.The oil pressure is still running about 15 psi at idle when it's good and hot and there's no noticeable oil loss on the ground or out the exhaust between 3,000 mile oil changes.
..............I'm trying Bob. But it isn't that easy with a wife who's going through menopause and three nearly grown kids who are trying to keep me from spending their inheritance. They all want to do my thinking for me these days.
Only 17% of your waste-heat 'budget' appears in the barrels. The reason Porsche went to aluminum jugs was so they could devote more of the cooling air to the heads. That is, the use of aluminum jugs was one PART of an entire system of modifications needed to pull more power out their engine and have it fit in the same chassis.
'Full-flow' doesn't make much sense. I assume you mean a full-flow oil filtration system... which still doesn't make much sense because filtering the oil doesn't have anything to do with cooling.
But if you meant adding extra oil cooling capacity... no again. To produce more power without shortening the engine's service-life you don't want the heat to get into the oil to begin with.
The latter point is one of the most commonly mis-understood characteristics of air-cooled engines, which you often hear described as 'oil cooled.' They're not. Indeed, ALL automobile engines are 'air-cooled' in that they must couple their waste heat to the atmosphere. The lubricating oil serves exactly the same function in a water-cooled engine as in an air-cooled engine, the only difference is that the waste heat that appears in the oil of an air-cooled engine must be coupled directly to the atmosphere, as opposed to being coupled to an intermediary coolant as is the case with a liquid-cooled engine.
At high levels of output you're going to produce more waste heat. Most of it -- about half -- blows right out the tail pipe but some appears in the heads, barrels, piston and valves AFTER WHICH some is transferred to the lubricating oil. The principle areas of transfer are via the underside of the piston and the area of the cylinder-head immediately adjacent to the exhaust valve(s).
The problem here is two-fold, the first being that oil is not an especially good coolant, the second is that the RATE of transfer is a function of the surface area, the rate of coolant-flow and the nature of the coolant itself. Simply clapping on a bigger cooler addresses only the heat that has ALREADY gotten into the oil, which is only a small part of the cooling equation.
The VW's heads and jugs were designed for a rather modest level of waste-heat management. When you generate waste-heat at a greater rate than those designed limits you end up with excessively high temperatures in your jugs and the areas adjacent to the exhaust valves
-- temperatures so high they COOK the oil rather than simply transfer the heat. The remaining oil does pick up a lot a heat but those areas are still hotter than they should be, resulting in greatly accelerated wear and possible detonation.
But it looks good on paper, right? :-) Just give the man your money, bolt on an oil cooler the size of a barn door and bingo! No worries. Unfortunately, all you've done is treat the SYMPTOM. The problem -- the excessively high temperatures -- are still there.
Thermodynamics does not respond to Convential Wisdom. Any more than engineering responds to the Democratic Process. The fact a majority of your buds -- and all of the folks trying to sell you stuff -- say a bigger oil cooler is the way to go doesn't mean it is.
All this, and i was only asking about an extra 41cc heheheh Thanks for the input chaps. I think i'll just stick with what i've got. Maybe pop the money somewhere else into the car......
What about those Flame thrower coils???? Just got a bosch bluey. Make any difference? power/mpg? etc
In my most humble opinion, your money would be best spent on a proper distributor and a simple electronic ignition - the kind in which you can replace the pickup with regular points on the road in case it flakes out. The most important part is proper timing and transitions. You will be MUCH happier without the consequences of screwed-up timing such as bad mileage, stumbling, overheating (lean) or fowling (rich).
You will NOT make your engine go fast with cheap bolt-on parts, but you might be downright amazed how quick a properly tuned and running ACVW can be - compared to the state of tune of most ACVWs on the road
Electrically, the blue Bosch coil is exactly the same as the black Bosch coil. The difference is that the older coil (ie, black) was manufactured using traditional tar, Bakelite and varnish; the newer blue coil is manufactured using modern plastics and SHOULD be more durable at high temperatures.
But as for all the claims of 'hotter' sparks, more energy and so forth... it's all bullshit. Why? Because the limiting factor is not the coil but the POINTS.
Your points are an electrical switch. The initial in-rush current to the coil approaches 10A., quickly dropping off as the magnetic field around the coil builds up. Average electrical load is about 3A.
However much current the coil is designed to use must pass through the points. To use a coil having lower internal resistance (ie, that draws more current) you'll have to also use bigger points.
If you don't increase the amount of energy going into the coil you won't see any increase in the energy coming out of it. Some after-market coils having a different windings-ratio, meaning they should show a higher output voltage, but if the input current is the same, bumping up the output voltage means the output CURRENT must fall.
Electrically, the stock VW ignition system, which is based on the Kettering patents of 1919, is about as complicated as a flashlight. Like all Kettering systems the output begins to 'droop' as the rpm increases. This reflects the decrease in the amount of time the points are closed -- when current can flow into the coil and build-up the magnetic field. When the points open, the field collapses. The rapid collapse of the magnetic field is what generates the high voltage output.
All modern ignition systems use something OTHER than a mechanical switch (ie, your points) to control the flow of current to the coil, typically a husky transistor that can carry more current than the original points.
If you want to improve your ignition system simply replace the mechanical points with a solid-state switch, such as the Pertronix or Compu-Fire. If you want to run higher rpms and a higher compression ratio, install a Capacitance Discharge ignition module.
But if all you want is one of those kewl blue coils that all the magazines say are so good, buy a can of spray paint.
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