Not boosted, but normalized.

[Drewbox]

One of the reasons why I got into air cooled VWs many years ago was how much in common the engines have with aircraft engines. Being a young aircraft mechanic looking for a new hobby, I figured VWs was the way to go.
One of the methods that some of the higher perfomance, higher flying aircraft use is to use a turbo charger. But they don’t use them to boost the engines, rather, they use them to “normalize” the engines, bringing the aircraft back down to sea level. Making the engines think they’re at sea level so they produce that same power at all altitudes.

I was wondering if anyone has ever done this with a VW.
Not to make incredible amounts of power and pull 10 sec quarter miles, but to have a little more pep in the streets. To have a constant (possibly flat) power curve without all the work and worry that goes with 15, 20, or even 30 lbs of boost.

It could help VW enthusiasts in higher mountainous locations to gain back a few lost horse power due to the altitude. Or to just make that full power and torque lower in the RPM range.

Again, has anyone ever done that?

[oprn]

I have thought about this a lot too. It is in effect exactly what is done when guys put a turbo on and limit the boost to 8 psi or less. That is more or less what I set out to do when I built a turbo engine 30 years ago. But it didn't work out that way in the end. It's called boost creep. Once you have all the equipment in place and you get a taste of what a pound or three of boost does... it takes a better man than me to resist the urge to turn it up a bit... and a bit more...

I actually met a fellow 3 summers ago that had a Buick 350 in his '34 Ford with twin turbos. It was limited to 3 - 5 psi he told me. He built it as a show car 35 years ago and only drives it 2 or 3 times a summer just to events. Beautiful car, lots of chrome under the hood!

Seeing as he was running on propane the 3 - 5 psi boost would in effect normalize the power difference between propane and gasoline. And the natural tendency of a turbo to speed up in thinner air would automatically give the altitude correction you talked about.
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Our cars get old, we get old but driving an old VW never gets old!

[BFB]

X's 2. the only people I see being able to resist the boost bug are the ones that only built the car for show.
_________________
Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.  
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1

[NJ John]

Boost is addictive.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[oprn]

I say go for it and keep us posted! It’s totally doable.
_________________
Our cars get old, we get old but driving an old VW never gets old!

[slalombuggy]

I only run 10# boost in my race engine. The only reason I put a turbo on the engine to start with was becasue there's no frickin air at Bonneville. My N/A engines at home (1100ft) would pull cleanly to 8000-8200rpm then I go to the salt (4800ft elv., as high as 9800ft corrected at mid day) and even with the enigne jetted correctly would have to fight to hit 7200rpm. The performance was like pulling a plug wire off, at home it put you in the seat and held you there, at the race, it just accelerated decently. This year with the turbo, It put you back in the seat and held you there for 2 miles.

Before the transaxle took a dump I saw the speeds I want to hit so I have no plans to turn it up.
I had an 84 GTI with a Callaway turbo on it that made 190hp (factory was 90hp) and all it did was eat head gaskets, then heads, then transaxles, no interest in repeating that.

[jpaull]

[NJ John]

5 pounds on my bug is fun, 11 pounds is funner.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[BFB]

[oprn]

It just seems to me that once you spend the money and time to set up a turbo on an engine that it is a bit of a waste to not use it. Aircraft are a completely different case because they are always changing altitudes thousands of feet at a time. So unless you live and drive in a very mountainous area your efforts and money would just sit there and do little to nothing.

Where I live I can drive for many hours and the altitude only changes maybe a couple hundred feet.
_________________
Our cars get old, we get old but driving an old VW never gets old!

[modok]

I like a big engine with low boost, still drives more like an NA engine.
It's like a muffler that actually increases power.

[BFB]

It is really incredible how much they do muffle the exhaust noise
_________________
Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.  
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1

[oprn]

When it comes to high boost pressures, 15, 20, 30 psi, I wonder if that pressure actually ever reaches the combustion chamber. Or is it that high because of intake/port/valve/cam choice restrictions? Or to put it another way, at what point do you start getting diminishing HP returns from adding more pressure? Just creating intake charge heat? In medical terms is that high pressure a symptom of intake manifold constipation?

If one were to graph % power increase vs % pressure increase for instance. I know it's going to be different for every build combination...

Modoc's big engine/low boost is not going to be there but a stock 1600 with 25, 30 psi boost might be?
_________________
Our cars get old, we get old but driving an old VW never gets old!

[BFB]

[modok]

There is a concept of choked flow.......where, beyond about 50% pressure drop flow through an orifice, mass flow depends only on the input pressure.

So, even if the engine is running above it's happy place, ports choking above the mach limit, you raise the input pressure, still more will flow through.
The MPG won't be great tho Pumping losses and dumping excessive heat though the intercooler.

There is a limit to suck, but how hard you can blow has no limits.

[oprn]

BFB, I hear you about turbo maps and that is valid. Back when I was a working stiff we also had the equivalent maps for valve flow to size valves properly. The interpretation of those maps and the actual sizing was normally done by engineering staff but we supplied the known data. This included process fluid/gas composition, temperature, differential pressure across the valve mainly.

As a boots on the ground guy it was not hard to detect when a valve was too small for the job. High inlet pressure was the big one followed by heat on the inlet side and cold on the outlet (more so in the case of gasses) and also sound. Often laboring of the pump or compressor was a clue too. Higher than expected current draw on electric motor and inability of gas compressor driver engines to hold RPM.

I know considerable flow testing has been done on flow benches at N/A pressure levels but has anyone ever done flow testing at boost pressure levels to determine optimum valve and port sizing under pressure? That would be very interesting to see! Way beyond my budget to do so.

Speaking of going beyond, this is way beyond the intended scope of the original question and is a subject that deserves it's own thread.

My apologies!
_________________
Our cars get old, we get old but driving an old VW never gets old!

[BFB]

yeh most threads seem to take different path than originally intended, especially if OP doesn't chime in and reedit things back to his focus.
so start a new thread about this if you want to Oprn, this place needs more things to talk about
_________________
Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.  
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1

[oprn]

It appears that Drewbox is not a frequent poster so he may still be watching this thread. It also appears from his photos that he is in a mountainous area so his premise could have a very valid purpose.
_________________
Our cars get old, we get old but driving an old VW never gets old!

[EVfun]

Along the lines of the original posters, I have thought about a low boost turbo setup on a stock engine. I was thinking perhaps 4-6 psi, mounting the turbo on top of a baja bug type header with the upward facing collector. Then blow it through the stock carb and boost reference the stock fuel pump. It seems to me that such a system would add just a few horsepower and likely eliminate the need for the factory intake heat riser. Ignition timing might tricky, perhaps a pressure sensing water injection system would help. (first feature creep...)

Then I remember that 48 horsepower doesn't really have any problem pushing around a 1100 lb. beach buggy.

This is this small turbo kit for the Bug engine. I'm not aware of any of these that are installed and running, but there was a thread about the kit.
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[oprn]

Yes! There is that creep already! 4 to 6 psi needs NOTHING by way of timing change or water injection with the stock 7.3/1 C/R. And if you go draw through you won't have to change anything on the fuel pump either.
_________________
Our cars get old, we get old but driving an old VW never gets old!