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One of the problems with building "oversquare" engines is that the small bore will limit the valve sizes you can use; you'll be putting 1300 heads on a 1500, and the lack of breathing will seriously limit the powerband. It'll be a torquey son of a b*tch, but I'm guessing that only with porting work on those small valve heads will it rev as high as a stock engine, and if left stock it'll definitely be a tractor, falling noticeably short of the stock rpm redline. Stroking a stock bore engine is not a popular build, as it's generally considered an expensive (and time consuming) way to achieve the extra cc's and the benefits don't outweigh the limitations. You'd be better off building a stock stroke 1600-1688-1776-1835-1915, or if you're really looking for bottom end/lower midrange, a short rod 74 or 76 x 90.5, thickwall 92 or 94. 

I know that this is not what you want to hear, but as I said (and Danny alluded to), this is not a popular build for a reason. Unless you have a very specific reason for doing this I think you're making a mistake. If you're building a Speedster engine, a 1600-1688 with stock dual port heads, 1776-1915 or even 74x90.5 or 92 with ported stock valve heads with a mild cam (Engle W100 or anything similar), dual 1 barrel carbs and 1 3/8" header will ultimately be way more fun. 

If you really want to build some thing funky (and just a little bit different) go the short rod (356/912 Porsche length 135? mm vs 137 VW) 74 mm crankshaft route. A 74 x 90.5 (1904cc's), 92 (1968) or 94 (2054) built as described will have fantastic bottom end/lower midrange and will go to 5000 rpm with power. Mind you, with anything bigger than 18-1900 cc's, you'll find dual Weber Ict's will limit the power output- I've been told that they're capable of 92-93 hp, so Kadrons would be the better choice for any of the bigger engines, and at some point (about 2 liters? not exactly sure where) the 1 3/8" exhaust may be the next limiting factor. So many choices...

Hope this helps. Al

PS-  fyi, through the late '60's and into the '70's VW built smaller engines for Europe (and the rest of the world?), @Gordon Nichols, all based on the latest engine case at the time, so although we never saw them here in North America, 1300's at that time with later cases were not uncommon.

Last edited by ALB

With ported stock valve heads, Engle W110 cam, kadron twin carbs and 1 3/8" header I've heard of a 1776 making 90 hp at 5500 rpm, but to make that hp number with 200-250 less cc's you'd have to rev it at least 500 (and more likely 1,000) rpm higher. With a W120 or W125 cam, now a smaller engine starts to suffer "down low" so that's why I keep suggesting bigger. When hotrodding the VW aircooled engine, displacement really is EVERYTHING!!! Bigger valves are of no use here, as properly ported stock valve size dual port heads are capable of 120-125 hp, and again, on an engine this small, are low end/midrange torque killer so they're really not an option either if you want "driveability". Look at the top of the page, you'll have a private message (give me 5 minutes) 

There are VERY available 69mm cranks that are counterweighted. I'd start there.

83mm piston gives you 1493cc. 85.5mm is a little too big, at 1585cc. Is it sub-1600cc you are looking for, or sub-1550cc? 

If they make a 84.5mm, which I don't believe they do, you'll end up with 1548cc.

If you go with a very slight increase to 1585cc via 85.5mm piston, you can use the CB Panchito head, which will give you a real screamer in that size, as long as you use their recommended cam, intake, and exhaust. I'd think Weber 40s with 28mm venturi, the proper cam, and lifters and you'll be making a powerful small engine. 

Yeah, I just saw your location and that explains everything (well, at least a lot more...)

A pair of Kadron or Solex 32 - 34mm carbs, an Engle 100 or 110 cam, have someone port the heads for the next size up valves (I'm sure someone over there knows how to do this for you) and also match-port the carb intake manifolds to the head ports.  Ask around - there may be some used, already modified, Formula-V engine parts that might be used, too, and keep you at 1549ccs or less.  The key for you will be a mid-range torque engine, rather than a high reving engine.

I would lean towards the stock exhaust tube size, just to manage the back pressure (ALB may disagree, but I'm not spec-ing a high rev'er, here), and I don't know what the MOT will allow for exhaust mods, but a header with 1-1/4" tubes might work well, or a stock-looking, 356-style Can muffler but with the long tubes for #2 & 4 cylinders to balance them.  As Al mentioned, it'll be a torquey little beast, if done right, and the torque is what you'll feel on back road cruising.

This brought back memories of modding my 1957 VW Oval sedan on the cheap back in 1967!  

Also, Chris, this site has a member look-up function up at the top so you might find someone close to you to contact about what they have built for their engines (and who built them) (we've seen about a dozen people from the UK/Scotland on here).  I understand the limitations imposed by the MOT that you must adhere to, but those guys may know what you can "fudge" and get away with.

Last edited by Gordon Nichols

I love this story. Chris, please, when you get a minute, school us on British engine taxes. I know they used to tax only bore size, which resulted in a lot of oversquare English engines.

We Yanks almost never have to work under displacement limitations, and it's made us a bit lazy in terms of hot-rod imagination.

Rest assured, you can build a strong 1500-cc mill and since you're budget conscious, your best bet is to start with a good, stock, German-made, counter-weighted crank, which will be 69mm. 

The cylinders are hard to find under 85.5 but you can still get 83s here

I think that gets you 1498. The rods may be an issue as the earlier (1500 wrist pins are supposedly smaller than the later 1600 and up, which everyone uses now. So you may need to get the rods worked on a little.

Heads I'm not sure. I ran a single-port, stockish 1300 (maybe embiggened to 1600--who knows?) in my MGTD replica for years before swapping in a Subaru. It scooted along fine and, according to the guy who built it 35 years ago, probably had over 250,000 miles on it when I pulled it. 

The engine is reportedly still running strong in a 67 Beetle.

At what rpm do you want the engine to make maximum power? How much bottom end/lower midrange (which will translate into poorer driveability on the street and slightly lousier mileage) are you willing to give up? Short of Stan's suggestion, there's not a lot you can do here. I know you're trying to max out the displacement, but de-stroking a crank to 64 mm to be able to use 87's (and gain 29 cc's) isn't worth doing- the custom crank grinding will cost more and now the engine will end up slightly narrower which means the cylinders will need to be shortened (more $$) and it will be more work fitting the engine tin and exhaust but there won't be enough benefit to feel it.

A regular 1500 with mild (W100) cam, raised compression (8 or 8 1/4:1), 34 mm carbs and Vintage Speed muffler will put out somewhere around 65-75 hp depending on the heads. I would go on the Performance/Engines/Transmissions forum on the Samba   https://www.thesamba.com/vw/forum/viewforum.php?f=12 and ask if anyone has ever put dual port heads on a 1500 because the best you can make a pair of single port heads is where the dual ports start. If you end up going with single port heads, talk to Web-cam- I believe they have some split duration camshafts specifically for single port head/dual carb combos that result in smoother running engines. 

@edsnova- I believe all rods for 69 mm crankshafts are the same dimensionally; it's the shorter 1200 rods with the smaller piston pin size, and the big end is different too (I think they're wider?).

@speedy chris- If you really want to max out displacement- take a 69 mm crankshaft, have it counterweighted and stroked to 71.5 mm. 71.5 x 83 gives 1547 cc's, and built with short (135 mm instead of 137) rods will be almost exactly the same width as a stock 69 mm stroke engine. Al

And btw- I really do like what @Stan Galat came up with as well!

 

Last edited by ALB

Reasonable power, gook mileage, low budget,runs smoothly, easy to maintain- something 2 literish,  cam/rocker combo that lifts the valves enough to use the potential of the heads and revs to 5500 or 6,000 rpm with power, Kadrons (on 35x32 heads) or 40 mm Webers/Dellortos (on ported 40x35 heads). Ported stock valve dual ports- 120-125 hp; with the big valve heads- 140 hp (or a little more). Any thing with this sort of power will be a blast to drive in a Speedster!

What does it cost to go over the engine displacement cap? 

Last edited by ALB
Stan Galat posted:

Total aside, but if I were limited in displacement, I would get one of these kits from thedubshop.com:

 

Stan , Will these work their magic with a dual port?  Kadrons.  What can I expect from performance with only the supercharger at this time?  Dual Kadrons, 1641cc. Standard base speedster. The SC is $400,  plus it looks like some pulleys, ss tubing to the carbs.  The site, I couldn't find details on all the goodies needed.  It says the EFI is coming soon, that's fine with me as that is going to be $3-4K more.  (The Tax cut didn't help me any)

I'll look some more.

speedy chris posted:

What would be the best way to go then if I forget the engine cc cap and accept the increase in tax. But I want to keep the budget of the engine build low (I mean low) and use off the shelf stuff. With an eye of gas mileage too.

 

What should I build?

The "builder's choice" kits on the CB Performance website will give you an idea about what's typical in displacement/horsepower/cost for street-driven performance Type 1s here in the states. These engines are not actually cheap. 

Keep in mind that these are long-block kits—so you still need carbs, ignition, fan housing, tins, exhaust & etc. 

That means a new 2005 engine like ALB suggests, with about 140 hp, will run you about $6k. Plus shipping. It's actually a little less to bump up to 2110cc and 150hp.

You'll also notice that CB's smallest offering is 1776cc. Everything's big here because we were never taxed according to displacement. So the only guys building small performance engines are spec racers, and they spend a lot to do what they do.

All's not lost though.

Like Al notes: much of the go-fast junk we put in our 2180s could work on a 1500. The Eagle cams CB uses in most of the hot street builds are just copies of mid-'60s Chrysler lobe profiles. A .460 lift/290 duration cam will bring your power band up to about 5500-6000, and you can use that a lot if you balance the crank, pistons and flywheel.

1500cc spinning that high, fed right, with the right heads and exhaust could do 90 horses. You'd be a little soggy in the low rpms, particularly with dual port heads, but very strong in the midrange and probably 90 ft-pounds at 4000.

You want better mileage and a little more "snap" at low RPMs, run single port heads and a smaller cam. Maybe like this one. Now you only rev to maybe 4800 but you could still make 75-80 horses and almost the same torque, and it's all-in by 3500 or so. 

VW "budget" engine building usually means shopping hard for used parts and massaging what you do end up with. Very doable here in the states with The Samba classifieds and swap meets. But to do it right you really have to know a lot more than I do—and probably a lot more than we can teach you in a couple message posts. 

 

edsnova posted:

A .460 lift/290 duration cam will bring your power band up to about 5500-6000, and you can use that a lot if you balance the crank, pistons and flywheel.

1500cc spinning that high, fed right, with the right heads and exhaust could do 90 horses. You'd be a little soggy in the low rpms, particularly with dual port heads, but very strong in the midrange and probably 90 ft-pounds at 4000.

You want better mileage and a little more "snap" at low RPMs, run single port heads and a smaller cam. Maybe like this one. Now you only rev to maybe 4800 but you could still make 75-80 horses and almost the same torque, and it's all-in by 3500 or so. 

 

speedy chris posted:

This makes things interesting, a 1500 which could make 90hp.

I think Ed's a little optimistic there, Chris. I've heard of a 1776 with ported stock valve dual port heads, W110 cam, kadrons  and 1 3/8" header making 90 hp at 5500 rpm- Gene Berg Enterprises did it way back when. Knowing what I know about Mr. Berg and his engine building ways I'll bet the compression wasn't optimal and you could get 3-5 more hp out of it, but the fact remains that with almost 300 less cc's you're going to have to wind up a 1500 to 6300? 6500? and maybe even higher to hit your magic number. You could bump the compression to the ragged edge and it might come close at the lower rpm, but longevity would always be suspect, you'd always have to make sure it gets fed the best gas possible and all it would take is a tankful or 2 of slightly inferior fuel and you've melted a piston or 2, scored cylinders, destroyed the heads and maybe even overheated (and warped) the case itself. 

Build a 1500 (or 1547 if you really want to maximize engine size); even 70 hp in these cars is a lot of fun, and if you find it's not enough then build something bigger.

I know this isn't exactly what you want to hear, but I'm just being realistic. Al

Last edited by ALB

Stuff like this exposes my rebellious reflex to stupid legislation, so I'd view anything I say through that lens.

A "1600" dual port is 85.5 x 69, or 1584 cc. I'm wondering who tears down the engine to determine the actual bore and stroke. Built on a 1500 cc case (with a 1500 cc S/N), I'm having a hard time believing that this would really raise a flag.

If I wanted the best engine possible, and slip under "the man's" radar, I'd get a pair of nice dual-port heads, some forged pistons, a decent cam, and Mario Velotta's supercharger kit. You'll notice from the dyno chart that on 11.5 psi of boost, it made 93 hp. More impressively, it made 127 lb/ft of torque right where you want it, at 2500 RPM. Perhaps ever better suited to a street car is the same kit at 8 psi of boost, making 111 lb ft at 2100 RPM.

Comparing that to his normally aspirated independent throttle body kit is like night and day- there's just 50% more power everywhere it matters.

I'm sure heat management would be an issue, and there would be not a single thing cheap about this set-up, but I think it's super-intriguing. This is 2L power from 1584 cc, and it's got ECM-controlled injection and spark. If I were doing this, I'd do charge cooling (water or methanol injection) for sure.

The blower is tiny, so there's no improvement in stepping up displacement much past 1600cc (perhaps a 1776, but IDK). Everybody talks about a 100 hp 1776, but getting there would make the engine a completely different animal - very peaky. You could run a stock ratio gearbox with a .93 4th and a 3.88 or ever 3.44 RP with this combo.

 Mario Velotta Supercharger Pic and Dyno Chart

Attachments

Images (1)
  • Mario Velotta Supercharger Pic and Dyno Chart

Cams and heads are better today than they were when Berg was squeezing 90 hp out of a 1776.

I don't know what a nice 1500 could do for sure, but I estimated based on what CB's modern crate engines do at 1914 and 2110. Basically, if a 2110 with a certain cam is making an honest 150hp at 6000 (which it does), then a similar grind set up in a 1500—given heads that flow about as well—would make 106hp. 

This is strictly on a HP-per CC basis and, since the engine design is identical in both cases, I feel it's reasonable.

Can this sort of thing be done in the real world?

Well...Here's Frank Camper campaigning in a 1600cc Ghia at Road Atlanta. He's running a Scat C65 cam, which gives a bit over .500 lift and like 309 duration, and the engine spins past 6600 rpm and propels his all-steel car past 130 mph on the back stretch. (Until he wipes the cam lobes).

How much horsepower is that? He doesn't say, but I'd guess he's doing somewhere in the 140-150 range with that engine which is (again) a 1600.

Now, boys, that's all I got. I don't build VW engines and I really don't know a lot about how to make air-cooled tech really work.

But I know how to do simple math, and this does pencil out.

Theoretically.

 

@edsnova- The guy wants to run regular gas and your talking about high strung race engines that are fed high octane race gas that rev to the moon with sky-high compression. A C65 cammed engine will go to well over 7,000 rpm with power if everything is right, and even with a bigger engine close gears are needed to take full advantage of the powerband. What do you think a little 1500 with stock 1st through 4th gear spacing that doesn't "get on the cam" until 3500 or 4,000 rpm is going to be like to drive on the street? My main transportation was a street bug with a 1750 that made power to 6500 and trust me, the thing would have fallen on it's face (and not been the small block killer and nearly so much fun that it was!) without close 3rd and 4th gears. And going any where on the highway sucked- big time.

And btw, porting a stock head isn't all that much different than it was done 40 years ago. If you really think you can double the hp of a 1500 by 5500 or even 6,000 rpm- build it, prove me wrong and I'll be the first to apologize and admit that you were right. I'll buy dinner and drinks the next time we meet. I'm not trying to be difficult here, but I think you're making promises you can't deliver.

speedy chris posted:

The theory looks good, worth a try in fact. Will it be expensive to make it spin that fast, I want to do this to a tight budget. And use regular fuel.

Yes, the theory looks good, but it doesn't always work that way. And yes, it will be more expensive and more maintenance intensive to make it spin that fast. Bottom end/lower midrange (where you will be 95% or more of the time on the street) will suck. This is a fun, drive any where, fair weather play car- upping the compression enough so that it requires premium fuel is one way of getting a little more from idle on up to redline (which a 1500 really needs to reach any where near the performance level you're looking for), and with the 1549cc limit I think it's a mistake to insist it run on regular gas. 

Educate yourself- talk to other replica Speedster owners in your country. Find out what they're using for power, what they think of it and their advice. Go on the Samba on the Performance Engines Transmissions forum and ask about putting dual port heads on a 1500, and how much power you can expect out of a mild street engine this size. People who have experience with building multiple engines will reply.

Again, I know this isn't what you want to hear, but it needs to be said. Al

Last edited by ALB

^ I regret that I have but one like to give for Al's comment. I guess cams are better, but at the end of the day, we're all still running Engle grinds that were somebody's best guess in the 60s. It's not like we've got variable valve timing- we don't even run different profiles for intake and exhaust. 

The only way to get everything with a small displacement engine is with forced induction (see every current auto manufacturer's offerings). All the tuner-boys know this, and all the VW drag-race types went turbo years ago.

Regardless, a fixation on total HP misses the fact that torque is what makes the world go 'round. If you want to have fun and drive on the highway (ever), you're going to need torque under 2500 RPM. Little engines don't make torque under 2500 RPM unless they are blown. A cammy 1.5L would need a 7 speed transaxle to be any fun at all to drive.

A turbo is more efficient, but a supercharger brings the power on quickly, without a lot (any?) lag. Turbos for small displacement engines get better and better all the time. Someday, they'll get down to the itty-bitty level that would be useful in a 1.5L VW Flat-4 application, but I don't know of any right now.

As far as regular fuel- this is a pipe dream. No high performance air-cooled engine is ever going to run on 87 octane. The limitations are baked in the air-cooled cake.

Last edited by Stan Galat

 

Here in the colonies, where there's no regulatory reason to stay under a certain displacement, common wisdom says that 2110 cc is the 'sweet spot' for most performance per dollar pound of build cost.

The plans for significant power from small displacement outlined above all seem more pricey than what a mild-tune 2110 might cost.

So, how many quid will you actually be saving per year if you stay under 1600 cc?

And, by Stan's reasoning, how would any inspector know that your 2110 isn't a 1600 just by poking his nose under the bonnet?

 

I have spoken to a VW guy at a UK retailer and he assures me I can build a 1500 with a DP case and DP heads. the basic fuel in the UK is 95 and the high octane is 98-99 octane I believe. I don't mind running on high octane but it is more expensive.

I can get 83mm pistons forged from mahle direct from Germany. I think the cam will be the next decision. I think twin 34mm solex and a vintage speed exhaust. I could take the heads to a machine shop to get the compression good.

I think if I could get the power to come in at 6000rpm then I think I can live with it and maybe I can get over 80hp...?

Chris:

Listen to ALB and Stan. They both know more than me.

I think you can build 1500ccs to 80-85 horsepower with available parts. And it might run on regular British gas (which for your purposes is the equivalent of our 90 octane mid grade). And I'd love to hear the tale and see the video.

But it won't be cheap. Or, if it is cheap, it won't be cheap for long. It will break. It will fail—unless it is build very right from very expensive parts. 

AND.

What Stan says about low RPM torque is very important. It is the key to happiness. 

An 85hp 1500 is not going to give you any throttle response below 3000 rpm. 

Most of any street-driven engine's life is spent below 3000 rpm.

So it will feel slow. Slower than the 50-horse single-port stocker driving next to you. 

Sure: once you climb out of the cam hole you'll be able to outrun that guy. He'll have to shift at 4500; you can rev to 6000. But (unless you want to drive everywhere like The Stig) you'll spend so little time up in that 3000-6000 range it'll feel like you wasted a lot of money and effort. 

You will not get good mileage.

Now, I know: UK ain't like the USA. You'll not be surrounded on the motorways at all times by Hemi Challengers and luxury monster trucks like we are. You'll be able to live with a high-revving, semi-high-strung 1500...if you want to have it that way.

But you will blow your budget. And you'll blow your budget again building a close(r) ratio gearbox to match your engine. (And then maybe again ripping that box out for a five-speed).

And you'll be having headaches trying to get the build done. And getting the build back on track when the first (or second) mechanic wanks off with a bunch of parts.

And why do you need 85 horses anyway?

You want a budget build under-1550 mill that's fun to drive? Build a near-stock 1500 with ported SP heads and single-barrel carbs. Use a stock-grind cam and maybe 1.25 ratio rockers to wake it up. Make sure the case is set up for full-flow oiling, and a remote oil filter. Use a stock late-model fan shroud with a dog house oil cooler. Put some money in the ignition system to avoid the ridiculous problems that plague almost all 009 disty owners.

Buy good small-tube headers, and run heater boxes. 

Make sure all the tin is on the motor, including the little stuff for the thermostat. 

Seal the engine bay so hot air can't come up from the exhaust.

Run a 3.88 gearbox with a .93 4th gear.

(Theoretically) you'll have an honest 60 horses or so at 4700 and the engine will pull strong from 2500, and it will run cool and get 28 mpg.

If you pay attention to the weight of your car, you'll have a plenty fast, plenty fun package, and you won't be sweating either the tax man or the next heat wave, because your engine will come correct.

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