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Although I may be, I hope I'm not the only newb who's stuck both feet in his mouth at one time or another - if not quite frequently. That said, I wanted to share some light reading I've been doing that totally clarifies some of the carburation complexities and exhaust/intake quandaries that keep me awake at night.

The titles:

1) Weber Carburetors by Pat Braden

2) Scientific Design of Exhaust & Intake Systems (3d edition) by Philip H. Smith & John C. Morrison

Functionally, these two books (read simultaneously) have made a world of difference for me. Although the Pat Braden book primarily addresses Weber carburetors, his contrasting analysis gives you a taste of other designs as well. The pictures are helpful for those of us who find it hard to read after staring at a screen all day.

These pictures also help when reading the Smith and Morrison book, because the lack of simple diagrams can be daunting for those of us who don't get to wrench very often.

Put simply, both books, taken together, give you a great foundation for understanding not only the science behind carburation, intake and exhaust systems, but also give you the tools to evaluate/appreciate the banter that goes on among some of the more veteran contributors in the SOC.

I would seriously recommend picking them up.

P.s. Have I inadvertently slipped into "The Madness" everyone keep talking about?

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Last edited by JoelP
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@550 Phil I'm still on the fence when it comes to my long-term, solo build project - water-cooled is slowly emerging as the front runner though. The engine I ordered from VMC, however, is air cooled. Although the pros and cons of each type of engine are many, what some count as cons - more maintenance, troubleshooting, etc. - in air cooled motors, I see as a chance to catch up on all the wrenching I've missed out on over the years.  As a younger man I only tore apart cars and motorcycles because they were my primary mode of transportation; hence placing short timelines on every issue/idea that came up. This time around is a chance to delve into all the details I couldn't afford to entertain previously, for better or worse.



In truth, I am 100% confident that everything I initially touch will be for the worse, with the results slowly improving for the better as I lean into the air-cooled world a bit more. For instance, I was completely surprised this weekend when I realized how hard it is to find hydraulic roller lifters for Type 1 motors; especially in light of how ubiquitous they are among other platforms due to their accretive power and engine-wear reduction benefits.

Last edited by JoelP

A fuel injected flat 6 P engine is hard to beat. Get in and turn the key. Instant smiles. I keep my Suby Spyder 150 miles away from my primary residence. Sure is nice knowing that it will start 100% of the time I find some time to break away from work and head to the mountains.
But my 356 Conv D will be my retirement car. I’m already making plans to gear down at work. And I plan on finding some time to get acquainted with my Type 4 and it’s Dellortos. But hey. Good for you. If you have the time and motivation to tackle a couple of 3 bank 911 carburetors more power to you. But if you work as much as I do right now and you savor those infrequent drives then maybe go for the fuel injection.

Hydraulic lifters in a performance type1 is a waste of time and energy and you'd be better off adjusting them every 3000 miles or so.

Mike Pickett and I are proof-positive that aircooled engines can be both aircooled and injected AND reliable.

Get in and turn the key is all I do now. Yeah, I'm still tweaking mine(Mike is done) but it gets closer every time I play with it.

@DannyP What's generally considered a "performance type 1?" Don't know why, but I've been working with the assumption that any naturally aspirated type 1 motor with a compression ratio under 9.0 and wasn't being revved above 7000 RPMs regularly wasn't considered "performance" or used in a "performance" manner. Again, this is based on . . . well . . . nothing. More generally, I've always been taught that unless you intend the engine to be used for racing and simply want to eliminate every possible point of possible failure, there is no mechanical reason not to run a roller lifter.

Nonetheless, do you (or anyone else for that matter) have any idea why it's so hard to find roller lifters for type 1 motors? It's well known that the friction from flat lifters (solid or hydraulic) not only causes wear, but is also a power suck. Frankly, I keep Googling "VW Type 1 Roller Lifter" and can't find anything except old threads about people experimenting with roller lifter fabrication. It's just super confusing because the debate over flat vs. roller lifters shouldn't be confined to water-cooled motors, seeing as every motor suffers when there's excess/needless/avoidable friction.

Oddly enough, I did notice that Raby's motors are all offered with "Roller Cam Shaft / Lifters" for an additional $3900; this may seem steep at first, but Raby is the only vendor I found who explicitly offers roller lifters for type 1 motors.

Am I totally in orbit with all this or am I simply missing an underlying concept or assumption that is causing my brain to catch fire?

Last edited by JoelP
@JoelP posted:

Am I totally in orbit with all this or am I simply missing an underlying concept or assumption that is causing my brain to catch fire?

First of all Joel, I can't tell you how much I like you and what you are bringing to the discussion.

I was where you are about 10 years ago - wondering why the hobby seemed frozen in amber, and not picking all the low-hanging fruit that other branches of the ICE tree have been harvesting for years.

After many engines and many experiments, I can tell you this: there are really, really smart people doing all sorts of things with the T1 VW engine - and if (almost) none of them are doing something, there's generally a reason.

To start with, yes - there are guys doing roller rockers in T1 engines. Keeping the lifters parallel is an issue, which can be overcome with some creative machining. Rollers are great. They reduce friction and heat amazingly well. The cam profiles can be a lot more aggressive without problems at the cam/lifter interface.

But the thing is, the flat tappet lifters aren't in the top 5 things that these engines typically lack. They aren't low-hanging fruit - they're fruit out on the leafy ends of the tippy-top branches, and there's a ton of things you can do before you get to that point.

Typical T1 engines have a really hard time with cylinder seal - the cylinders don't want to stay round, and the rings don't want to seat. This is partially a function of poor parts - but even with JE pistons and Total Seal rings, getting a good seal on a Mahle 94 isn't all that easy because the cylinders don't want to stay round. They're thin and they distort as they get hot. Getting this squared up will be worth 10x what a roller cam brings to the table.

As far as the valve-train- the valve-springs are a lot stronger in a typical T1 engine than they are in a lot of applications, because the pushrods are long and there are a lot of harmonics in the valve-train. The typical T1 rocker is kinda flimsy, and the entire setup often requires gentle ramps on the cam and strong valve-springs (which create a lot of heat with the flat tappet). If you just stick a roller lifter and a super-aggressive cam profile on there - yes, there will be less friction and heat, but you will have done nothing to control the valve more accurately. The pushrods will still flex, as will the rockers, and you'll need a killer valve-spring to control the entire mess.

Far, far more productive is to get the weight of the entire arrangement down. Bleeding edge T1s have titanium valves, beehive springs, tapered aluminum pushrods, and the lightest lifters possible, activated by a cam with gentle ramps (opening and closing). Such an engine doesn't need a lot of parlor tricks (like roller rockers) to stay cool, simply because the nose and seat pressure of the valve-springs doesn't need to be crazy high to control the valve. Heat is pretty easily controlled, even running higher than average compression.

This is why the hobby seems like it isn't moving forward. Running lazy ramps, weird pushrods, stout rockers, and titanium valves works really, really well - but it's hard to explain and doesn't seem like a place where spending money gives much return. It doesn't show up on a dyno, but it does show up in your daily life.

If you want to put roller lifters in your car - knock yourself out. I did a twin-plug configuration because I wanted to see why nobody was doing it. Now I know.

Your mileage may vary.

Last edited by Stan Galat

So lets break this down a little bit.

Performance VW engines: IMHO anything bigger than a stock motor and/or more than 7.5:1 compression(which was stock BITD). 1776 is performance. Over 8.5:1 is performance. Even a 1915cc with stock heads and mild compression is a performance motor.

There is a distinction to be made here: Roller cams/lifters(cause the lifter has rollers on it, not the cam) are a completely different thing than roller rockers. Hydraulic lifters are a third thing entirely, designed to remove the periodic valve lash adjustment.

VW did hydraulic lifters in their Waterboxer Vanagon engine. The waterboxer was an amalgam of type 4, type 1, and new watercooled cylinders/heads. I believe Bernie Bergmann used to do the conversion to Type 1 motors.

I've never heard of a roller lifter/cam on a flat VW engine. I'm not saying they don't exist, just that I've never heard or seen it. There are plenty of roller cams on pushrod V8 engines though. EDIT: I guess Stan HAS heard of them.

There are certainly plenty of roller rockers. I have an older set of Pauter 1.5:1 on my 2165cc type 1. These have roller bearings on the rocker shaft AND the tip of the rocker. So the rocker rolls back and forth across the valve tip and the rocker itself rolls on the rocker shaft. I've got 45,000 miles on them. The valve tips, pushrods, and rockers all look great. The only sign of wear is the anodized finish has faded in color intensity. The ones Pauter sells now have a bushing in the rocker and a roller on the tip.

As Stan references, shallow ramps/lighter springs/lighter valves and pushrods can make the valve train live a good, stress free life. Power is found in the heads, intake, and exhaust. There are thicker cylinders, and also cases and heads and cylinders with 6 studs to clamp it all together better. It's all out there for the taking, just add money.

If a 94mm cylinder was the largest I was looking for, I'd buy Nickies, which are north of $3000 for 4 with forged pistons. I weighed that option. I bought Mahle 94s instead. My engine originally came with them. After 35,000 miles they were worn. A new set of Mahles and some total seal rings was about $500. I'll spend that six times to break even with one set of Nikasil cylinders.

Spend your money on heads/intake/exhaust.

The best money I spent on my engine:

1: Crankfire ignition

2: Dry sump system(keeps oil where it needs to be rather than outside the engine)

3: Injection

Last edited by DannyP

@JoelP, I won't presume to have gone as far into The Madness as Stan, but I do know the the hp/$$ ratio is much better with the low hanging fruit as he says.  Simply going to a larger displacement is a good first step.  Consider 1915cc as the bare minimum for a "performance T1."  If I were to do another air-cooled engine I'd probably start with a 2054cc or 2110cc Pat Downs engine.  A good cam with Downs' fancy Panchito heads and a couple of Webers would be a nice engine.  Raby is an artist but his prices are stratospheric.  You have to ask yourself if the juice is worth the squeeze to you.  As Stan always says, your mileage may vary.

Last edited by Lane Anderson

Distilled down as far as I can take it:

Unless you have a background in engines and really get off on the esoterica of boundary layers in airflow, flame fronts in the combustion chamber, the net effect of a smaller cam with bigger ports vs. bigger ports with a smaller cam, etc. - just get in line for a Pat Downs 2110.

Tell him what your expectations are, and let him fill in the blanks. You'll get the best engine possible for the dollars spent.

There will be plenty of room to make improvements after the engine is delivered. All 3 of @DannyP's "best money spent" improvements can be made after the engine is in the car.

This morning, I reread what I had written yesterday. I kept making a mistake that really changed the intent of what I had to say. Corrections are below:

After many engines and many experiments, I can tell you this: there are really, really smart people doing all sorts of things with the T1 VW engine - and if (almost) none of them are doing something, there's generally a reason.

To start with, yes - there are guys doing roller cams in T1 engines. Keeping the lifters parallel is an issue, which can be overcome with some creative machining. Rollers are great. They reduce friction and heat amazingly well. The cam profiles can be a lot more aggressive without problems at the cam/lifter interface.

But the thing is, the flat tappet lifters aren't in the top 5 things that these engines typically lack. They aren't low-hanging fruit - they're fruit out on the leafy ends of the tippy-top branches, and there's a ton of things you can do before you get to that point.

Typical T1 engines have a really hard time with cylinder seal - the cylinders don't want to stay round, and the rings don't want to seat. This is partially a function of poor parts - but even with JE pistons and Total Seal rings, getting a good seal on a Mahle 94 isn't all that easy because the cylinders don't want to stay round. They're thin and they distort as they get hot. Getting this squared up will be worth 10x what a roller cam brings to the table.

As far as the valve-train - the valve-springs are a lot stronger in a typical T1 engine than they are in a lot of applications, because the pushrods are long and there are a lot of harmonics in the valve-train. The typical T1 rocker is kinda flimsy, and the entire setup often requires gentle ramps on the cam and strong valve-springs (which create a lot of heat with the flat tappet). If you just stick a roller lifter and a super-aggressive cam profile on there - yes, there will be less friction and heat, but you will have done nothing to control the valve more accurately. The pushrods will still flex, as will the rockers, and you'll need a killer valve-spring to control the entire mess.

Far, far more productive is to get the weight of the entire arrangement down. Bleeding edge T1s have titanium valves, beehive springs, tapered aluminum pushrods, and the lightest lifters possible, activated by a cam with gentle ramps (opening and closing). Such an engine doesn't need a lot of parlor tricks (like roller lifters) to stay cool, simply because the nose and seat pressure of the valve-springs doesn't need to be crazy high to control the valve. Heat is pretty easily controlled, even running higher than average compression.

This is why the hobby seems like it isn't moving forward. Running lazy ramps, weird pushrods, stout rockers, and titanium valves works really, really well - but it's hard to explain and doesn't seem like a place where spending money gives much return. It doesn't show up on a dyno, but it does show up in your daily life.

If you want to put roller lifters in your car - knock yourself out. I did a twin-plug configuration because I wanted to see why nobody was doing it. Now I know.

Sorry for any confusion this may have caused.

Thanks for everybody’s insights. Because mine will be a 2332cc motor with 8.2:1 compression, I’ll definitely bookmark this thread for reference.

FYI, because I have no illusions about avoiding engine swaps or complete rebuilds in the future, I’m totally stealing all of your good ideas. Whether I end up building the perfect motor or a deadly monstrosity that ends with a burnt down garage or a fiery crash, only time will tell; although I hope for the former, there’s a little part of me that wonders what the latter would be like.

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