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Sun Jun 02, 2019 9:19 pm

Just kind of a curious question. Anyone have an article/video/any comparison between a super 90 porsche engine (or the 912 evolution of it) vs a beetle engine? Just kind currious what the fundamental differences are between the two and if/how one could spec a beetle engine to similar performance (redline, power peak, etc) to it just out of curisoity (dont plan to spec a build off it)

Im mostly just curious what the differences from factory between a 1600DP and the super 90 were that allowed for so much higher of a redline and the significantly increased power were given the similar size and look of the engines

Sun Jun 02, 2019 9:31 pm

The engine made about 50 HP/liter, which is very mild by today's standards. What made it a good engine for the time was dual carburetors or one barrel per cylinder, a bit more cranking compression, and a decently tuned exhaust. The engine was all-in around 6000 rpm, so to answer your question, yes. A T1 engine could be made to match or exceed the 356 output. I think it was a 90x64 engine.

A strong 85.5x69 1600 could make over 120 HP at 6K rpm with some work.

Sun Jun 02, 2019 9:34 pm

The porsche is a pretty NEAT engine but actually we can beat it with a type-1.
Comparison main difference in character is the heads, we see the porsche seems to have more difficulty with lean mixtures, and a weaker signal to the carbs. Porsche is MORE like a hemi shape head, but kind of the wrong way.

Would be even better if they tilted the intake valves and left the exhaust straight, performance wise. tho as it is the way they did the exhaust port/valve might COOL better.

Sun Jun 02, 2019 9:57 pm

oh, I have 0 doubt we can beat it with a T1. We can trounce in fact with how many have built 200hp T1s. I just like learning about new engines so I was curious what the intricacies of it were (was it full flow for example?)

Sun Jun 02, 2019 10:06 pm

AI think it's interesting they DID NOT offset the rod journals to strengthen the crank as VW did with the 1300 and newer engines.
Instead they used the narrower rods, which was good, but thicker bearings, which was bad.

instead of studs they used through bolts for the mains, at least in some of them, which did go though the oil passage.
Same dimensions as a type4 through bolt, but larger size, ARPM cases used the same through-bolts.

Sun Jun 02, 2019 10:38 pm

modok wrote: AI think it's interesting they DID NOT offset the rod journals to strengthen the crank as VW did with the 1300 and newer engines.
Instead they used the narrower rods, which was good, but thicker bearings, which was bad.

instead of studs they used through bolts for the mains, at least in some of them, which did go though the oil passage.
Same dimensions as a type4 through bolt, but larger size, ARPM cases used the same through-bolts.

Wait. Do beetles not use non-concentric rod journals? Tbh I am very much so a beginner with it comes to engine internals (I'm currently trying my damnedest to find an online ICE design course to take/go through since I am an ME, but I cant seem to find anything between very basic and top level).

Sun Jun 02, 2019 10:42 pm

yes the rod journal of the crank is not perfectly centered under the cylinder, instead offset 1mm toward the nearest main bearing.
This allows the center web of the crankshaft, between rod journals, to be thicker. That's why old 40 horse engines break cranks more often. i don't think there is any course that will include this trick, but it's been done for a long time.

Sun Jun 02, 2019 10:48 pm

modok wrote: yes the rod journal of the crank is not perfectly centered under the cylinder, instead offset 1mm toward the nearest main bearing.
This allows the center web of the crankshaft, between rod journals, to be thicker. That's why old 40 horse engines break cranks more often. i don't think there is any course that will include this trick, but it's been done for a long time.

Ah. That makes a lot of sense. and yah, im not looking for inticacies, just kind of intro to engine design if I can find it. Something that talks about optimal timings, cam effects, windage, etc.

Sun Jun 02, 2019 10:55 pm

it's all in the heads.
Valve sizes, chamber, flow, cam timing.

Bottom end just holds it together.
Has a lot to do with how long it lasts, but not much at all to do with how it runs.
Porsche case, rods, crank, were just fancier, more labor, better materials, not better design tho.
Making it work by pouring money on it.

Sun Jun 02, 2019 11:11 pm

modok wrote: it's all in the heads.
Valve sizes, chamber, flow, cam timing.

Bottom end just holds it together.
Has a lot to do with how long it lasts, but not much at all to do with how it runs.
Porsche case, rods, crank, were just fancier, more labor, better materials, not better design tho.
Making it work by pouring money on it.

Yah, that was kind of my basic understanding already, just dont know any of the specifics yet. Its actualy suprisingly hard to find info on how different things effect engines online. I am more and more getting th feeling im just going to have to buy a textbook tbh

Honestly, I feel like a utter baffon trying to iunderstand the stuff I find of beetle engines regardless of my degree (still cant believe my school didn't even offer a class on ICEs. All I got was research simulation optimization and turbine design)

Sun Jun 02, 2019 11:20 pm

Not so fast, there. I think it is harder to mimick the 90's performance in all aspects than you may think.

Of course, the bore/stroke ratio is different, the 90 has a 74 mm crank, and shorter rods by 1mm.

The Porsche's intakes do have a little less angle to them, they're flat, and they're 40s for a 1600. And the hemisphere sorta works, with the piston tops, to push the charge towards the plug.

That said, there are a lot of VW heads which will outflow the 90's heads, probably by a factor of 2 or more...so a VW 1600 could waaaaaay outperform the Porshe 90's 1600 (thinking JPM), in all aspects except one: cooling.

The Porsche's heads have a whole lot more area per cc. I think the fan turns slower, too, and might be smaller or with less fins than the VW, I don't really know. What I do know is that they can keep the engine cool, even at full load, full speed. Like 24 hrs non-stop.

Do that with your hopped-up bug.

Sun Jun 02, 2019 11:21 pm

Eskamobob1 wrote: I'm mostly just curious what the differences from factory between a 1600DP and the super 90 were that allowed for so much higher of a redline and the significantly increased power were given the similar size and look of the engines

The Type 616/7 B4 (356 B, Super 90) was a bit of an oddball/bastard for it's time, but I do get the intent here: it had a forged counterweighted crank, short/stout conrods, unique heads, & dual 2-bbl carbs.
Super 90s could be revved about 800 rpm higher than other 356B 1600s thanks to a special cooling layout that gathered in more air, plus nitrided crank and cam-bearing surfaces, a lighter flywheel, stiffer valve springs, light-alloy rockers, larger-diameter (by 5 mm) main bearings, and cylinders lined with Ferral, a coating of steel over molybdenum.
S90s also had a unique oil pickup system that allowed the engine to draw lubricant from the sump’s full side in hard cornering, thus ensuring proper lubrication at all times.
It was an important advance that Porsche racers had wanted for several years and was especially welcome in the high-performance 90.

Sun Jun 02, 2019 11:28 pm

Advanced engine technology by Heinz Heisler,
four stroke tuning by A.G. Bell
Anything about cylinder heads & cams by David Vizard

yeah the stroke and rod ratio was the right direction for the porsche. Small difference, but some.
I think the VW should have had much shorter rod, because the rod ratio causes no imbalance in a flat engine, unlike a straight four.
Long rods were OLD thinking, and yet it had long rods until 2002 :shock:

Mon Jun 03, 2019 7:44 am

modok wrote: Advanced engine technology by Heinz Heisler,
four stroke tuning by A.G. Bell
Anything about cylinder heads & cams by David Vizard

yeah the stroke and rod ratio was the right direction for the porsche. Small difference, but some.
I think the VW should have had much shorter rod, because the rod ratio causes no imbalance in a flat engine, unlike a straight four.
Long rods were OLD thinking, and yet it had long rods until 2002 :shock:

I think the long rod makes sense due to the nature of the engine intended for its life. where as if it had been intended to turn more RPM a shorter rod would have made more sense.

Mon Jun 03, 2019 8:00 am

I have a friend who is a long-time, now retired Porsche shop owner/racer, etc...

His quote was that a 356/912 motor is a 36hp with 100hp heads. Always sounded about right to me.

Mon Jun 03, 2019 8:11 am

The super 90 is a 82.5 X 74 engine. I has serious power limitations when compared to the T1 engine. It is derived from the 36 hp VW engine. Think of it this way, 36hp/356 mini block, T1 small block, T4 big block.

The 356 engine has displacement limitations, bore spacing limits cylinder size to about 90mm and the connecting rods hit the cam lobes with anything more than 74mm stroke. Some have reduced the rod journal size to fit longer strokes but that reduces crank rigidity.

On my 356 I wish I kept the engine stock and used a big T1 engine for my power needs. It is now for sale with the big 356 engine.

https://www.thesamba.com/vw/classifieds/detail.php?id=2273244

Dan

Mon Jun 03, 2019 8:18 am

I can't tell you how many times people say "you should put a Porsche engine in it".

I tell them "sorry but I like to go FAST".

Mon Jun 03, 2019 9:55 am

We built my friends big 36HP Challenge engine using a Porsche Pre-A engine case. We didn't know it was a pre-A at the time we just thought it was a modded 36hp engine case with through bolts for the center studs. :D

We used a Porsche crank that was already 3rd under on the rod journals so we had it ground to 2" Buick and used 5.4 h-beam rods. We also had the grinder offset grind the crank and we squeezed a 77mm stroke out of it. We hand cut the fins on 87mm barrels that were grooved t fit the stud spacing. And used WW cylinder heads. The cam was from Mr. Motorhead. Now we just have to figure out some better period correct carburation.

He installed it in his 11 second bug to see how it would do at the strip and ran a 15.xx with it.

brad

Mon Jun 03, 2019 10:25 am

I had A 356A with a stock 1958 Porsche engine but it had an extractor and for a while It ran a VW Transaxle and it was so much quicker than any VW I had there really is not a comparison. The Porsche cam is not much of a performance cam well the Super 90 is a little bit of a cam about like running a VW W-100.
Here is a Video of my 1679cc VW Engine W-100, stock flywheel and exhaust for the bus and the same kind of Zenith NDIX 32x25mm Carbs the Porsche ran.

Mon Jun 03, 2019 12:41 pm

Glenn wrote: I can't tell you how many times people say "you should put a Porsche engine in it".

I tell them "sorry but I like to go FAST".

yea, I like to go even faster