Why haven't roller cams come to the VW world?

[ach60]

Why haven't roller cams come to the VW world?
Is there specific reasons VW can't use a roller cam?
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Al

[GTV]

They have but mostly (all?) in race applications.

Takes a lot of work to modify a case for rollers.
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[Alstrup]

Also, roller cams require extremely high spring pressure. Something that has a lot of downsides. The newer direction is cam designs that are more accurate and requires much less spring pressure and support about the same hp as rollercammed engines deliver

[nsracing]

Right now, it is drag-race only applications = MONEY!

If you have the money, shops plenty to build you whatever you want. It is not for the everyday bystander.

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They have, but VW guys are too cheap.
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[mark tucker]

Im cheep and ive got 2 of them....spring pressure??? that is dependent on the application. did chevy go way up on thier springs when they went roller in all of thier v8 engines??? no. did they lighten up the valve train???no, they just stuck a roller cam in and let it go and it worked awesome. so why isant in these??? because these engines/cars went out of production long ago. or I think they would of. I am supprized nobody is selling a street roller kit.

[Alstrup]

MMMMhh! Mark, you may be right to some extend with the V8´s They are not my main engine area. but the few I have seen all had extremely high valve spring pressure. Something like 400 and climbing lbs over the nose. and they were just hopped up street engines.
In an ACVW I really do not see the need for roller cams on this side of 100 hp per liter. With today´s knowledge its possible to pull 230 solid hp out of a very streetable 2275 with single springs that has about 240 lbs over the nose. - This spring my colleage built a 2 liter Opel (GM product, but still with 2 valves per cylinder) for Group H historic rally. We worked with this engine on paper over a period of about 6 months. Then he built it. It pulls 230 hp @ 8000 rpm on sgl beehive springs. All within the rule book. If you want to go racing and pull 9000 rpm you of course need more. Then we can begin to talk about the need for roller cams. On this side of 250 hp. no need.

T

[earthquake]

The biggest advantage I see is there would be a lot less lifter failures and flat cams. how deep ie the lifter bore on a VW case? will it support say a Ford hydraulic roller lifter? from the contact edge of the roller to the oil port is 1.70", you could have smaller base circles which means more room for stroked cranks.
You would have to figure out how to keep it straight so it would not dig into the cam.

Casey
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[mark tucker]

chevy is smaller dia that ford so that would be better in this app.
yes hoped up motor use much higher springs.hell alomst 30 years ago i was running close to 500 open pressure on my street car with R274-286 @050about .650 lift. the good thing about roller cams is you can have a wild cam and still have lots of lowend due to the fast ramps& lift rate. you can get more power eazely with them. but if your gonna be zingining it and going for the glory then you you need the killer springs&other valve train to go along with your application. I havent a clue as to what open pressure my vw is now with the bugpoop 4046 springs 165 on the seat witch is almost what my roller was 30 years ago on the seat. and those were heavy lifters back then. and heavy 3/8" stems on heavy steel valves. I think the way to go is big lobe low lift high ratio rocker so your not throwing the lifter all over the place. .300 tall lobe with a large journal like a ford roller lobe and a 1.5-2.0 ratio rocker. my hyd roller is .344 lift witharound 245@50& 1.65 jessel rockers.not finished yet. too many other peoples shit got in the way. my solid roller is much bigerlike .440 lobe [email protected] 874 jessel roller lifters&jesell rockers.also...not finished yet.life and other stuff seem to keep getting in the way..... when all my V8 stuff is gone I will have oh somuch more time and space to do it all..and more $$ so i can have the cylinders I want.mI do need 3 roller blanks.I may buy or make them. I was going to buy them earlyer this year but ..somethen came up and I missed a good deal on them. snooze and looze.

[Stripped66]

1) Money: Roller cams, lifters, valvetrain, and the modifications to the engine case are expensive.

2) Competency: You have to be a competent engine builder to plan out and assemble even a mild roller-cam set-up for a VW. There is no frame of reference in the collective base of knowledge for setting up a mild roller-cammed street engine. You have to be resourceful in researching information, everything from spring pressure, installed height, spring diameter, valve-stem length, keeper and retainer heights, etc. What lifter are you going to use, how are you going to modify the case for that lifter? Understand that most VW engine builders (hobbiests and professionals) lack the detail to even set up rocker geometry correctly for a flat-tappet engine. Trying to find accurate information about roller cam set-ups is difficult outside of high-end race engines (where details are scarce to begin with), and trying to scale that information down to a given street-driveable application is based on what? Experience? What/who's experience? Intuition? Get real. So, either learn as much as you absolutely can until you are confident you've become an expert, or find the few people who've already done that.

3) Advantage: The maximum valve opening rate of a flat-tappet cam is limited by the diameter of the face of the lifter. The very large diameter head of the Type 1 flat-tappet lifter allows very aggressive cam profiles. There is little performance advantage when using a mild roller cam over the newer flat-tappet profiles offered for Type 1's. Certainly, that advantage becomes more pronounced on race engines; but for a street engine, there's more performance to be gained by taking the premium of a roller cam set-up and putting that money into head-work, induction, fuel-injection, whatever. The cost-benefit of a roller-cam is generally low, unless you're chasing every last inch of HP available in an engine combo.
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[Stripped66]

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smart money says his rollers are in V8 engines, not VW.

[Stripped66]

[bugguy1967]

Mark is referring to V8 stuff, which may need little to no modification to install.

[modok]

IMO the camshaft and it's bearings need to be 3x stronger and more rigid to fully realize the potential of a roller cam. It is possible, but not practical.
I think a steel body lifter with ceramic nub on the end, in type-4 diameter, steel cam, would be more practical as it would reduce friction while accommodating flex and misalignment, but it would have be developed and would not be cheap.
Remember the VW originally had a strange nub follower but they converted to the American type follower.....maybe they had it right but were ahead of the times?
Could be

[Stripped66]

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V8 answers to VW questions is very confusing and misleading IMO.
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[Stripped66]

[modok]

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FWIW, most VW guys can't even get their push rod lengths correct, so having a "roller cam kit" for a VW engine is a recipe for disaster.
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