what are the pros and cons? which is suited for daily driving duty? which is more reliable? which is more fuel efficient?
thanks in advance, guys!
Short stroke engines tend to spin up faster because there's less throw at the crankshaft and tend to produce more horsepower but higher up in the rpm range(and less torque, overall and especially at the low-end).
Stroker or long-stroke engines tend to produce more low-end torque and horsepower at the low-end, too big a stroke and they won't rev up as high or as quickly as an engine with big bore and small stroke. Also keep in mind, torque is what launches a car off the line, horsepower is what pushes up in high end.
Here's an example, a Formula 1 engine produces about 850 hp(at 18K) and 200 ft/lb. of torque from a 2.0L V8. Amazing isn't it, it gets better. It has a bore to stroke ratio of 2 to 1, i.e. the bore is twice as big as the stroke. It doesn't produce torque because they don't need it, these cars only weigh about 1300lb., yes the ultimate go-kart. Here's the part most everyone misses when they talk about horsepower and accelerating a car up to speed(aside from absolutely ignoring torque numbers which just about everyone does), this engines gains power at 20,000 rpms--per second! So a chevy big-block twin-turbo that puts out 850hp is not the same as a Mclaren F1 V8 that puts out 850 hp, neither is a Ford Powerstroke diesel that puts out 850 hp.
Now if you're appling this to an air-cooled VW, also keep in mind, drag racers do use full-circle stroker cranks, the point to get the revs up and keep them up there.
A stock engine is 85.5 x 69. Going bigger on the bore size and not increasing the stroke means opening up the case for bigger cylinders. Going bigger on the stroke means also machining the case and possibly adding spacers to get correct clearance for the cylinders, and getting a new set of pushrods and cutting them to the right length. I used to have a shop building engines, we didn't use cylinders bigger than 92mm(90.5 was preferred) on our stroker engines because we found that the stock cooling system isn't up to the task and 94s weaken the case too much.
Stroker cranks are great though, the torque difference is really what these engines need.
Unless you're doing some weekend racing, I wouldn't recommend building an engine with just bigger bores, which is what practically everyone does and has done for years. A 1776(90.5x69) or 1835(92x69) or 1914 means you've opened up the case for these jugs but kept the same stroke and shifted the power band up, i.e. you need to rev. it to feel the power. These engines don't last as long as stock ones.
Hope this helps.
>What combination would you recommend if you want more torque and a bit more power? No drag racing, just spirited drives on the weekend... stroke it? bore it? or both it?!?
I'd try to even out the bore to stroke ratio more, as in go bigger on the stroke and a little bigger on the bores, a 74mm counterweighted crank and 87 or 90.5mm cylinders and a mild camshaft, if you don't mind it being a little louder, go with straight-cut gears on the cam, too(extra hp). If your budget or time or whathaveyou only permits increasing bore OR stroke, I'd increase the stroke.
I don't like to quote actual numbers of power increases, you're just guessing unless everything is factored in(carbs, fuel injection, ignition, stock or aftermarket heads, etc.) and you actually dyno the engine. People pull numbers from wherever all the time. If you really want to know what your engine is putting out now vs. afterwards, get some 0-60 times first on an abandoned road and weigh yourself and the car at a truckstop. Do the same after you modify it.
>And if it is for a weekend driver and some times drag strip what combination do you guys recomend ???
Of course im thinging obout going turbo
In this case, you'd probably want a bigger bore ratio for an engine that needs to be wound out at the high end, like 87 or 90.5 or 92 mm cylinders. Keeping the stock stroke on the crank of 69mm you still might want to get a counterweighted crank for those high rpms.
If you are going with a turbo, the stock compression setting of 8 to 1 should be fine. If you start having knock problems, either switch your rubber fuel lines to neoprene and add, or substitute, alcohol(E85 is the new trend) or add a knock sensing ignition system. Race gas is pretty expensive for the weekend racer at $8/gal.
Quote, originally posted by Dj_Rasta_vw » Well i started looking for this kind of pistons and it says that i need to spesify strocker or non strokers what is the diference
Height. You'll usually find "A" and a "B" versions - A being the standard style and B being the stroker style. The rods will obviously be different too.
Modified by thomaschh at 2:52 PM 9-17-2007
Quote, originally posted by Kafer Wolf » how about for daily driving duty? im thinking of near-stock with a little more push. what's the ideal combo?
Probably not stroker (just one man's opinion). Ideal depends on how much you can/want to spend. 1776 is a pretty standard upgrade.
>how about for daily driving duty? im thinking of near-stock with a little more push. what's the ideal combo?
Kafer, there's no need to go bigger in volume to get more power out of a stock VW engine. I built a super-1600 for my bus as my daily driver, I've put 8,000 miles on it and it pulls strong with good torque and has given me no problems so far. My mileage actually improved too, this is another myth that more power means less mileage--VWs are a little underpowered. I still have a few more things I want to try with it as well.
Consider how the stock engine was designed and what it was built for, to be simple and reliable at a low initial cost. If you build a monster engine hogged out to 96 mm pistons and an 86mm crank running 20 lbs. of boost, well you're getting way, way far away from what these engines were originally designed to do. Just remember, most modifications you do to these engines usually result in the life expectancy going down from the 100K it was intended for--stock. This isn't the rule, just if you're not careful, too much material taken out here, it runs too hot, or you're just trying to squeeze too much power from something only designed for 50hp, well it might not last long.
Let's also keep in mind, all these modifications we've discussed are for the weekend mechanic, if you want a 400hp turbo motor that has an Autocraft case and pro-heads, well, you'd already be talking to a builder like Paradise VW and shelling out several thousand $$. Also keep in mind, the hp numbers on a race engine vs. street engine tell you nothing about HOW they perform. A race motor is ALL ON or ALL OFF, nothing in between. You either have your foot on the gas or on the brakes in a race car.
Now Kafer, if you optimize the stock motor, you will open it up powerwise quite a bit, look at the whole picture first. Before tearing into the block, you can
-get a better ignition(pointless ignition is smoother but doesn't add powerwise, mostly maintains it at all times, i.e. a Petronix or Compufire won't swell up like points and reduce the spark when they get hot. An MSD ignition with a 6A box or Electromotive will add a bit more power.)
-Exhaust(no need to go crazy with a 3" merged drag system, fat boy mufflers work well, stay the hell away from anything with EMPI written on it, CIP1 has some good systems--I like the Euro dual Tip they sell, the box, pea-shooter style worked for Porsche for all these years with their 400hp motors. Be sure to get some j-pipes too(only if you don't need heat) or high flow heater boxes from Kymco, later style weld-on flanges are recommended too.)
-Ratio rockers(if you plan on going with a different compression ratio or different crank you may want to hold off on this, otherwise, 1.25 or 1.4 rockers are always a plus)
-Induction(A bigger carb-if you have a 30PICT a 34PICT would be better, or dual carbs will help the engine breath better. Tuning dual carbs can be a bit of work though and need adjustment every now and then. Fuel injection is also a big plus. Many people are scared of FI, but they're really very straightforward systems, you can either retrofit a later L-jet system from a later bug or T4 bus, go with Megasquirt which is a cheap programmable DIY system, or CIS injection or ?? There's tons of info. out there on this, check out http://www.shoptalkforums.com and look at fuel injection. I had CIS on my '66 bus for about a year, it was great, no computer, just a pressure based system I set the mixture and idle speed on only one time)
Tearing into the block or case, you can:
-Get a counterweighted crank(these help produce more torque)
-A mild camshaft(Engle 110 is recommended, a 120 is NOT for the street)
-Straight-cut gears on the camshaft and crank(a little noisier than helical-cut, not much though, you pick up a bit of horsepower here too though)
-Tap the engine case for a full-flow oiling system(this way you only have to change the oil every 5,000 miles and it keeps everything inside a lot cleaner. Stay away from in-out spin on filter pumps, these are junk and don't flow enough oil back to the case for anything but a bone stock engine--even that I'm not sure about.)
-Balance the internals(This makes everything smoother and lets the engine perform. The more power and engine puts out, the more everything HAS to be within specifications. You can match balance the weight of the rods with the pistons and clips, i.e. the lightest rod will mate up with the heaviest piston, etc. I went so far as to balance my engine for each component to within .5 gram)
-Heads(many options here, the easiest is putting aftermarket mid-range heads on with bigger valves, keep in mind though this will shift the power band up higher in the rev. range. You can have your stock heads ported and polished keeping the stock valve size, this will keep low-end torque up and increase hp. You can also semi-hemi cut the heads and flycut them. I plan to do both next on my heads, hemi-cutting improves the combustion chamber charateristics and burn of the mixture, while flycutting raises the compression. I plan to bring the compression on my engine up to 9.0 to 1(raising compression increases power considerably), engine knock doesn't begin until you raise it 9.4 to 1. If you change the compression by flycutting, you'd have to check your rocker arm geometry clearance as well.)
-Forged pistons(better than cast pistons, but not essential.)
-Lightweight lifters('nuff said)
-Lightened flywheel(this adds, or allows, the engine to produce more hp but at the cost of producing less torque by having less weight it has to spin. I don't do anything that sacrifices torque, again this is what you feel pulling you off the line.)
-Add a doghouse or upgrade your doghouse cooler to a T4 one(the T4 is bigger, an engine that is too hot loses power. You'll have to modify your cooling shroud as well.)
-Install a windage tray(this is an option for you weekend racers to keep the oil from sloshing around, especially if you plan on autocrossing. Not necessary for just a street car.)
There's a lot to be said for optimizing a stock sized engine, in off-road racing where the rules mandate keeping the stock bore and stroke, they're still able to produce a 1600(1588cc) single-port with a restrictor on the carb that puts out near 100hp! Mind you they have 11 to 1 compression and run on race gas and cost about $5000 and this isn't something you could drive in traffic, but you can see what can be done.
One more thing,
Quote, originally posted by Dj_Rasta_vw »
Well i started looking for this kind of pistons and it says that i need to spesify strocker or non strokers what is the diference
As Thomas said, on a stroker engine the rod comes out further so the hole for the piston pin is cut closer to the top of the piston so it levels out at the top of the cylinder.
Well, my wrists are tired. Hope this helps again, I'd rather be at home working on my cars than stuck out here for work.
What Jade Wombat suggested is almost the same motor that I ran for awhile and would recommend it. If I could change a few things, they'd be.... I recommend using use a engle FK-65 cam with 1.4 rockers, i like using high rocker ratio cams because they tend to be more gentle on lifters and associated valvetrain. now heads, heads are where the power is at. Stock heads with a fluff and buff does nothing, you'd be lucky to make 75-80hp with some stock garbage heads. If you threw on some heads that flow, like CB Performance's CNC'd roundports you could make 20-35 more hp with out changing drivability and reliability. Carb wise you cant go wrong with Dual Kadrons, easy to set-up and I only adjusted them everytime I changed the oil, back when I was a noob, its that easy! Also you dont need a windage tray its waste of money on anything other than a race car, just get 1 1/2qt deep sump and you'll be set. Personally I hate stock, its too boring. after building my 1776(daily driver) ill never go stock again. Next motor is going to be a 2176 (daily driven), I cant wait!
Saw this over in the Golf forums, kind of related to what we were talking about, the world's fastest minivan.
The Renault Espace F1 is manufactured by Renault, Williams . 3500 cc 40-Valve V10 engine, 800 BHP/ 597 kW. 228.6 BHP per liter. weighs 1300 kg, maximum speed of 310 kph/ 194 mph and sprints in 2.8 seconds from 0 to 100 kph/ 60 mph.
This topic got me thinking about HotVW's Mileage Motor Project and what I would've like to do with it (I've brought this up numerous times).
"Our first thoughts were to build the engine as "square" as possible, meaning that the bore and stroke are equal. However, starting with the 1600's 85.5mm bore, that meant increasing the stroke from 69mm to 84mm or 86mm. Not entirely impossible mind you, but it does start to get tricky. Since there are no 85.5 "B" stroker pistons available, a setup like this would require extremely thick spacers under the cylinders. Unless longer rods were used (requiring even thicker spacers), it would also require a massive amount of material removed from the piston skirt for clearance. The idea of a new aluminum case with raised deck came up, but for the 85.5mm bore that would end up being an expensive custom built component, and would still result in the engine being extremely wide, and difficult to install in a stock Bug without trimming metal."
HotVW's, November 2006 (52-53)
I really wish they would've stuck with their original idea of the doing an 84 or 86mm stroke, making it either a 1929cc or 1975cc engine. The idea of making an engine with that kind of displacement into a mileage motor is so intriguing.
They brought up the idea of using a raised deck aluminum case http://www.cbperformance.com/c...=1230 which I saw that CB offered, but said that it would 1. require metal trimming/fabrication which they didn't want to offer to their readers and 2. The raised deck case with standard bore would be an expensive, custom component
I see that CB offers the standard bored raised deck case, so what's expensive about it? And if it's simply a matter of trimming metal I wish they would've have gone through with it. Well over 100hp and staying over 30mpg - is it possible?
Check these guys out, they do aluminum jugs and custom pistons http://www.lnengineering.com A setup with these parts probably would make a true high mileage motor, pricey, but very interesting. A motor with aluminum case, aluminum jugs, aluminum heads, it would run ice cold!
They might be able to make a set of custom 85.5 pistons as well or point you in the right direction. I like in the movie 'The World's Fastest Indian' where he made his own pistons.