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Goingslow
Samba Member
Joined: June 15, 2025
Posts: 4
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 Posted: Sun Jun 15, 2025 1:44 pm Post subject: Limitations of vw engine? |
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I have been offered to buy a type 1 chassi.
Don't know a lot about aircooled vws though.
The T1 engine is limited to about 105mm bore or there about I guess, the bore spacing is 110mm? The cylinders would be siamesed, but that may or may not matter much?
What is the limits in stroke? I guess that the engine will be too wide if too much stroke is used?
The crankshaft looks quite weak from the pictures I have seen (I have never dissembled an AC vw personally).
So how weak is the crankshaft design?
Would a shared journal be stronger (non boxer crankshaft)?
What are the stock crankpin and main journal sizes? Maybe big journals and short stroke is the way to go on these engines to keep them together?
What failure points or weak points do you guys who run these engines see?
Anything else I should know? |
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modok
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Joined: October 30, 2009
Posts: 27662
Location: Colorado Springs
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| Posted: Sun Jun 15, 2025 1:50 pm Post subject: Re: Limitations of vw engine? |
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Bore spacing is 112mm
The crank sizes are in the service manual or bearing catalog.
How will you cool siamesed cylinders? Run it on methanol?
shared crankpin...."I don't think so Tim"
the flexy crank isn't great for high RPM, but neither are the extremely long pushrods and skinny camshaft.
Even so, people run them run to 7500 rpm long stroke or even higher short stroke, and they don't last long but racing is racing.
Max bore with standard head stud location is about 94mm
With aftermarket blocks and heads and larger stud spacing have used 4" bore
The point of diminishing returns (strength wise) on stroke is somewhere between 74 and 84
What would help crank stiffness is added main bearings like the subaru or spreading the cylinder spacing to thicken the crank webs, or just thicken the crank webs by inventing impossible machining process to make a solid crank like a roller crank.
Look at a subaru ej25 engine, or a Pauter big block, it's what you will end up designing, already built. |
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Wreck
Samba Member
Joined: July 19, 2014
Posts: 1313
Location: Brisbane
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| Posted: Sun Jun 15, 2025 3:04 pm Post subject: Re: Limitations of vw engine? |
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| It all depends what you are trying to achieve ? Road car , drag car , circuit car , off road racer ? |
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Dale M.
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Joined: April 12, 2006
Posts: 20806
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Sun Jun 15, 2025 3:31 pm Post subject: Re: Limitations of vw engine? |
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Probably you can go up to 2332 CC and 250 HP... With a limit about 7500 RPM...
More practical would be around 2000cc (78x92) and about 100-120 hp (at the wheels) and still be very streetable....
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nsracing
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Joined: November 16, 2003
Posts: 9743
Location: NOVA
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| Posted: Sun Jun 15, 2025 4:37 pm Post subject: Re: Limitations of vw engine? |
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We got another troll who woke up today and wants a 1000hp aircooled beast foaming at the mouth for street? 
The VW aircooled configuration is one of few 4 cylinders hitting the 9-sec mark on the 1/4 mile. The design is plenty strong -depending on what parts you use.
The motors come in all flavors- choose your poison and what your wallet can afford. |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 79490
Location: Sneaking up behind you
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| Posted: Sun Jun 15, 2025 4:50 pm Post subject: Re: Limitations of vw engine? |
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| nsracing wrote: |
| We got another troll who woke up today and wants a 1000hp aircooled beast foaming at the mouth for street? |
Then stop feeding him/her/it.
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Goingslow
Samba Member
Joined: June 15, 2025
Posts: 4
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| Posted: Mon Jun 16, 2025 1:30 am Post subject: Re: Limitations of vw engine? |
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From what I know, the subaru is not very strong. Tiny crank webs amongst other things.
Pauter engines looks like they get good runs though.
250 hp with 94mm bore is good.
Anyway interesting forum... |
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oprn
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Joined: November 13, 2016
Posts: 14752
Location: Western Canada
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| Posted: Mon Jun 16, 2025 5:06 am Post subject: Re: Limitations of vw engine? |
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The Subaru engine will outlast the air cooled VW engine by a factor of at least 4 to 6 times! We had 300K on ours when we sold it and my cousin had 500K on his when he hit a deer. The stock VW engine made anywhere from 40 to 80K tops and from what I see on this site the hot rodded ones are lucky to get 20K.
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halfassleatherworks
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Joined: December 09, 2018
Posts: 805
Location: Reno NV
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| Posted: Mon Jun 16, 2025 7:15 am Post subject: Re: Limitations of vw engine? |
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| Glenn wrote: |
| nsracing wrote: |
| We got another troll who woke up today and wants a 1000hp aircooled beast foaming at the mouth for street? |
Then stop feeding him/her/it. |
Just use a Wright CH-2120 |
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EVfun
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Joined: April 01, 2012
Posts: 6150
Location: Seattle
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| Posted: Mon Jun 16, 2025 7:41 am Post subject: Re: Limitations of vw engine? |
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The first obvious problem with the idea of a shared rod journal is the camshaft. Each cam lobe is used for the 2 opposite cylinders so they have to be opposite in the firing order. Stock firing order is 1, 4, 3, 2.
| Code: |
cylinder layout
flywheel
3
1
4
2
pulley |
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| Wildthings wrote: |
| As a general rule, cheap parts are the most expensive parts you can buy. |
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Schepp
Samba Member
Joined: March 22, 2020
Posts: 470
Location: NorCal
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| Posted: Mon Jun 16, 2025 7:57 am Post subject: Re: Limitations of vw engine? |
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| Just swap to an LS and send it. |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 79490
Location: Sneaking up behind you
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| Posted: Mon Jun 16, 2025 8:00 am Post subject: Re: Limitations of vw engine? |
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| Goingslow wrote: |
| From what I know, the subaru is not very strong. Tiny crank webs amongst other things. |
Sure... 1400 WHP is crap
Link
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Dusty1
Samba Member
Joined: April 16, 2004
Posts: 2095
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| Posted: Mon Jun 16, 2025 10:38 am Post subject: Re: Limitations of vw engine? |
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| Glenn wrote: |
| Goingslow wrote: |
| From what I know, the subaru is not very strong. Tiny crank webs amongst other things. |
Sure... 1400 WHP is crap |
It's way easier to make 200hp with a 2 liter 16 valve Subaru than it is with a 2 liter 2 valve per cylinder VW.
Stick your 2 liter Subaru in a Bus. Use it to tow your VW to the track.
The Subaru numbers you need to know:
175hp from a 2.0 or a 2.2 normally aspirated, conservatively tuned.
275 turbocharged horsepower from a WRX.
375 turbocharged horsepower from an STi.
600 turbocharged horsepower from a tuned WRX or a tuned STi.
Any more than that is just bullshit and / or bragging rights. You better have a fat wallet to keep up with the greasy trail of broken parts. It's like any other time you let your reach exceed your grasp.
Here's the cheat to the bonus question: Don't worry about the crankshafts. 2.5 Subarus eat heads like they're party favors. My (now several) tuner buddies keep the lights on and and pay the rent by replacing 2.5 heads.
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Goingslow
Samba Member
Joined: June 15, 2025
Posts: 4
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| Posted: Mon Jun 16, 2025 12:54 pm Post subject: Re: Limitations of vw engine? |
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As said, from what I know.
If I'm wrong then I'm happy to be corrected.
So are anyone running a subaru bottom end?
Split heads and a new cam could be used I guess. What bore spacing does the EJ use?
Maybe a cheap way to get a solid bottom.
Just get a junk engine and take rotating assembly and put into new case.
99.5mm pistons are better than 94mm too.
After that you could make all hp you want if they are good for 1.4k hp.
And way cheaper than buying a t1 scat billet crank that's weaker anyway. |
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Dusty1
Samba Member
Joined: April 16, 2004
Posts: 2095
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| Posted: Mon Jun 16, 2025 1:54 pm Post subject: Re: Limitations of vw engine? |
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| Goingslow wrote: |
As said, from what I know.
If I'm wrong then I'm happy to be corrected.
So are anyone running a subaru bottom end?
Split heads and a new cam could be used I guess. What bore spacing does the EJ use?
Maybe a cheap way to get a solid bottom.
Just get a junk engine and take rotating assembly and put into new case.
99.5mm pistons are better than 94mm too.
After that you could make all hp you want if they are good for 1.4k hp.
And way cheaper than buying a t1 scat billet crank that's weaker anyway. |
Do you know the difference between linear and logarithmic?
I ask because there's no such thing as cheap horsepower. Every so often someone finds something that no one else noticed resulting in big power for little money. But for the most part the quest for power and speed is logarithmic. Not linear. The expense I mean. First thing you learn is twice as expensive is nowhere near twice as fast. Twice as expensive again may be a little faster. As you evolve you begin to understand how much power you need. Evolve further, you understand how much power you can afford.
If you want to understand power look at marine diesels, big Volvo Pentas for example. Or... 6-71 Detroits. You might find those in a ferry or you might find one in a truck.
Let's talk about the venerable 6-71.
It's called a 6-71 because it has six cylinders, 71 cubic inches each. That's more than 1 liter per cylinder, hey, 426 cubic inches and it's supercharged. You might think it makes crazy horsepower like a supercharged Chrysler Hemi. A stock Hemi is 426 cubes. A nice street hemi could use a blower borrowed off an old Detroit. That's where the old timers got their blowers. The big diesel must make crazy power, no?
"No" is the right answer. A 6-71 GMC diesel makes... drum roll, please... it makes 165 horsepower or 225 horsepower for the high output version.
GMC designed their diesels as a modular concept. The made 2-71, 4-71, 6-71, 8-71 and then twelve, sixteen or twenty- four cylinder versions.
Point is these engines are huge while the power they produce is "unimpressive".
How is it that "165hp" motor will push a fifteen ton (gross) city bus?
Can you imagine a 165hp VW motor in a GMC city bus?
There is another axis that bears scrutiny, expected service life. Those old GMC diesels trudged along for hundreds of thousands of miles.
The real obvious part: Diesel Bus motors are quite large. Freakin' huge, really.
If we were to chase after more diesel horsepower we would use the usual hot rod tricks. Feed it more fuel. Blow on it harder. Spin it faster.
And...
We would quickly arrive at a point where the power exceeds the structural limits of the design. It's gonna blow chunks, hot oily chunks.
Every motor will blow chunks when pushed hard enough.
How many times can you pay for your really quite impressive (on paper) motor to turn itself into hot oily chunks?
https://www.kennedyeng.com/engine-adapters
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txoval
Samba Member
Joined: January 23, 2004
Posts: 3842
Location: The Woodlands, TX
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| Posted: Mon Jun 16, 2025 2:56 pm Post subject: Re: Limitations of vw engine? |
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Could go with the TF-1 case
84mm crank and 4” pistons
2.7L |
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jpaull
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Joined: February 22, 2005
Posts: 3643
Location: Paradise, Ca
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| Posted: Mon Jun 16, 2025 3:51 pm Post subject: Re: Limitations of vw engine? |
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When looking at a aircooled vw type 1, everything looks weak. One nut to hold the flywheel on, air cooled, tiny little head studs, and comes with a flexible magnesium block that is not even one piece. Its like a cruel joke of a engine to try to make power with and stay together.
For all those reasons, its alot more rewarding to be successful do just that.
If your not wanting to dive in and learn about what can make a aircooled vw really live, and mix and match subaru/vwaircooled into one engine, then you should really swap a complete engine, and not try to mix and match.
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Wreck
Samba Member
Joined: July 19, 2014
Posts: 1313
Location: Brisbane
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| Posted: Mon Jun 16, 2025 4:57 pm Post subject: Re: Limitations of vw engine? |
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| all the information you have given is a type 1 chassis . what are you going to want all this power for and for how long, seconds or hours ,hundreds of hours etc ? |
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Dusty1
Samba Member
Joined: April 16, 2004
Posts: 2095
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| Posted: Mon Jun 16, 2025 5:49 pm Post subject: Re: Limitations of vw engine? |
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| jpaull wrote: |
| If your not wanting to dive in and learn about what can make a aircooled vw really live, and mix and match subaru/vwaircooled into one engine, then you should really swap a complete engine, and not try to mix and match. |
An Oxyboxer is a proper juxtaposition of Subaru and VW. No Subaru parts in it. Something like 30 years ago I gazed at my brother's Vanagon engine. It was obvious the Vanagon engine grew out of basic Type 1 architecture. One might expect it to be an outgrowth of Type 4 but...
...well, anyway you can mill the water jackets off a Vanagon and end up with an Oxyboxer. Not for the faint of heart, though.
You either need to become a machinist or write a lot of checks to a machinist. That's where Pauter, Autocraft and the like come in.
| Wreck wrote: |
| all the information you have given is a type 1 chassis . what are you going to want all this power for and for how long, seconds or hours ,hundreds of hours etc ? |
We all get snookered by Top Fuel. Those guys rebuild between rounds. How hard can it be? More to the point, how expensive? I don't know but I been told $50k per run, win or lose. That's the nature of nitromethane. The early nitro racers round out PDQ you either purge the nitro vapor from your engine or it's gonna blow up the moment you start it. That evolved to replacing a shopping cart full of expensive parts each and every run.
Of course the OP's question is, "How big can we build it?" That answer is pretty easy. Around 1965 or 1966 a Volkswagen was intended to be a 1200 or a 1300, either 64mm stroke by 77mm bore or woo- hoo, the Big Boy supposedly 50 horsepower 1300, same 77mm bore only stretched out to a honkin' 69mm stroke.
Various J.C. Whitney catalogs trumpeted the benefits of big bore pistons and cylinders. VW Corporate quickly added their own "big bore" pistons and cylinders to give us the 1500 and 1600. With a rebel yell we cried,
"More, more, more!
But there's only so much room inside an engine that was designed to be 69mm stroke with a 77mm bore. Turns out you need a little clearance in a bunch of places at the top of the case to clear a counterweighted stroker crank. There's only so much room before the crank and rods whack into the cam.
Bear in mind the stock case was designed for a 77mm bore.
Wouldn't it be handy to have an aftermarket case with a raised roof, a dropped cam centerline and enough material to move the cylinder studs out to accommodate really huge cylinders? Oh, wait. Trick cases have been available for decades. They solve the obvious problems while creating several more. Like...
How do you fit an engine wider than stock into the stock hole without cutting vintage sheet metal?
If it won't fit the engine compartment, how are you going to fit it with a shroud necessary to keep it cool?
If you're not an engineer or a machinist, where you gonna get all the trick parts needed to make it fit and function? See, that's the real Catch 22. If you have the tools and skills to build it you build it. Then you sell a bunch of them to your buddies. That (hopefully) generates enough cash to keep the whole enterprise rolling.
| Dusty1 wrote: |
If you want to understand power look at marine diesels, big Volvo Pentas for example. Or... 6-71 Detroits. You might find those in a ferry or you might find one in a truck. |
I mentioned marine diesels in hopes of enlightening the OP to how burly parts need to be to handle big power.
The 1400hp Subaru guys built it to notch a record. It's not how the bear dances...
The bear will dance like a mofo for a few seconds before dying of a heart attack, multiple aneurisms and a stroke. 
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ORANGECRUSHer
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Joined: June 09, 2006
Posts: 3489
Location: West Coast (Michigan's)
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| Posted: Mon Jun 16, 2025 6:16 pm Post subject: Re: Limitations of vw engine? |
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I can't beleive with a post count of 0 and half-assed questions you guys didn't send this guy to pack sand and do his obligatory research. All those questions are easily found ten times over if he had just not been lazy and asked a bunch of vague, broadranging, situation dependant questions. I'm very disappointed.
PS. it's my time of the week... sorry 
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