gt37vgt

no need for solid lifter in a 16v it has 35mm hydraulic lifters and 7mm stems witch is the industries standard in 4v per cylinder engines of the last 30 years and the same set up they happily spins past 9 in many engines..
Also if you are whitey engine geek and you want to build an optimum head its much easier to get valves lifers and Ti retainers than an 8v set up .. i will have my full valve chain built for well under 1000 by cutting down nascar del west ti exhaust valves and 42g VW lifters 12$ ea

67King

Agree to an extent, and disagree to an extent. Is quench (i.e. pistons) that critical? No. Valvetrain? Well, that durability, and on the street with only brief bursts, probably not. But cam timing? That will affect your spool time, pretty drastically, and that can have a BIG impact on the "fun factor," which is the most subjective measure. All I'm saying is that I've been there and done that. With a 4V engine, you don't need the big cam profile to move a lot of air like you do on a 2V engine. A 2V engine is more either/or. Either drivability or big power. On a 4V, you can have your cake and eat it, too.

Duke

I respect your knowledge but I suspect your "been there done that" doesn't include a 4v 944 turbo engine.

What Raceboy said, and what I concur, is that the stock 4v cams work very, very well in a turbocharged environment.
I use stock 968 cams and I have yet to see a better curve from a 4v turbo 944/968 engine. It drives and idles like a stock engine too (until you use more than 5% throttle).

Chris White

Solid lifters on a 16v are not needed. The valve train parts of the 16v head are very light. For high end engines I will go with Ti retainers and lighter valves and valve springs. The stock lifters are good for somewhere over 8k rpm….I haven’t floated one yet!

All true – and I really l like people that just try stuff to see if it works. On the other hand I have found that most of my customers that want a 16v engine like the concept because they appreciate the engineering and details, so to use an 8v piston as the basis for a 16v engine doesn’t quite appeal to them.


Hey, ‘whitey engine geek’…I resemble that remark!
Oh, and on the cutting the hood for the twin cam drive….there are other solutions….I am not into the Mad Max look…..!

Raceboy

Regarding turbochargin the stock 4v 944/968 engine, I can pretty much say BTDT because Duke's engine that blew due to serious overboost came from the Markus951 "Jägermeister" orange 951 and when Markus built this engine, we discussed countless hours both on the phone and irl what to do and what not.
Goal was to build a "budget" 968 turbo engine (may sound weird, isn't it?) and in my opinion it succeeded.
Pretty substantial amount of my know-how (educated guess to be accurate) went into this engine.

Ok, enough of self-promotion

Raceboy

I know that one: dry-sumping the and lowering engine

schip43

Oh so the engine can be lower? That is an elegant solution but on the dollar scale we just went from crazy to insane?

So far the stock 944 S setup sounds to be the simplest solution, what is the rev limit on the combo? I have only seen one 944 S ands that was years ago.

67King

On edit, toning it down. I've messed with enough engines to know that the same physics applies to all of them. Sorry you don't see it that way.

schip43

QUOTE=67King;8587492]On edit, toning it down. I've messed with enough engines to know that the same physics applies to all of them. Sorry you don't see it that way.[/QUOTE]
Well I'm gonna guy with( Merkur guy ) I mean 67King.

It seems to me that either way would work and if you have a 3 liter the LSA my not be that big a deal but on a 2.5 it might be.

Clearly you can do it either way and the thing will run but it seems to me that if you do the twin gear conversion you can optimize each cam individually.

If you run the stock 944 S setup you can't, so a regrind to change the LSA. That's my take on it so...moving on...

67King

I would expect the extra 20% displacement would make a slower spool (which is what is at issue here, NOT idle) more tolerable.

On regrinds, they are typically done to make cams "bigger," or more lift and duration. I can't imagine a slight tweak to a profile would be difficult, but you also typically make the base circle smaller, which necessitates some needed changes, usually in the form of longer valves, a stem cap, or a spacer under the lash adjusters in the case of follower designs.

I would personally rather run two sprockets for the flexibility. But I used to know a guy who would do reginds for a little over $100. I need to see if I can track him down to see if he can do a DAMB cam with a unique profile, and what it would cost. I am guessing that would be a much more cost effective solution.

JohnKoaWood

At the end of the day, it comes down to what the engine (car) will be used for, how much power you want to make, and how long you want it to last...

Anyone can slap on a turbo and go, but getting a target power level and making it last while being drivable on the street... takes a little bit more finesse!

All respect to the monster power engines that have been made, but how many ran for any real duration of time (measured in years, miles, races) are still running?

Dukes newest engine (16V variocam 3L) is a MONSTER, and should last a good long while.. a similar build US side would easily exceed 10K.. in machining and supporting mods alone...

While a 16V 2.5 can be done, doing it on the cheap will leave something behind, weather it be streetability, reliability, power, or some combination of the 3..

FWIW, there was an effort (group buy) a while back for 928 cam sets, made from new billets.. in reality, any grind on them would be possible...

Chris White

Except for Australian physics – it always seems to make less horsepower at the dyno!

Maybe they should have a conversion factor to DP (Dingo Power) instead of HP (Horse Power)…..

Chris White

Duke is currently tuning up an 8v monster engine…..should be some really good numbers from that one, better than most 16v engines!

schip43

Hmm, but if your not changing lift would you have to change base circle? And yep I got the lazy bit, don't need to build a motor to do that!

Yeah, I'm still stuck on the hole in the hood thing!

OK, I give up! What is a DAMB cam?

JohnKoaWood

Is that the motor to go along with his race car?