Twin cam Type 4 builds

I know it would be nearly impossable,BUT

Any builders plainning to try and build one. That would be one tough engine, if it were a sturgess belt drive.

I wonder if it could even be done. I have seen a T-1 done and it was wild.

I am curious as to how big it could be punched out to. and if It had at the classic style 4 cam shroud. even better.

Gents break out your slide rules.

I believe it can definitely be done. Either bring a lot of money or have your own machine shop available would appear to be the criteria.

A local hot rod type here in San Diego named Pete Aardema (sp?) has a Chevvy small block converted to SOHC. Ever seen one of those? He'll sell you one if you ask. He also has it mounted TRANSVERSELY in the back seat area of (I think) a '34 Ford. And it all works. He rives to many local shows. Figured it all out himself, including his homemade transmission adapter into the third member. Now there is a designer / machinist par excellencet!!

No doubt he could do a type 4 (which is also my engine, by the way). No, I can not afford to have him do one for me! But he is a hell of a nice guy, even nicer I'd bet if you paid him.

Barry,

There is an SOCH engine availiabale; the 911-4 howeve it is not a DOCH.

Jack

DOHC flat boxer engine? Isn't it called a Subaru? Turbo to boot.

I have seem a few 4 cyl. 911 engines. My next question is the valve and head configuration like the old carrera twin cam engine but with a belt drive, or is the soch very different.

The Carrera twim cam has a complex cam drive that made a lot of noise.
A belt drive would enable you make a head with hopefully better cooling and higher flow.

Of course a T-4 head is a toqure monster. and a different head could hurt that.

THe Type one I have saw was all trimed in polished alumium with a flywheel triggered ignition and EFI it was Be-U-te-ful!

If I can find a pic I will Post it .

Been done- Many times..

The answer is 100mm 911 cylinders coupled to 964 heads..

Some of my friends in the Netherlands are working on the apfelbeck project and they use twin intake valves and one exhaust valve actuated via an overhead arrangement...

Or build one of Dean Polopolous's four cylinder 911 SOHC engines with dual ignition heads, 102mm Mahle pistons/cyls, and dual Weber 48 IDA's. With Gerry Woods' GE60 cams it should make about 240 BHP and be very reliable.

And when it breaks find out that only one individual can supply you with ANY part for it.

It may make gobs of HP, but it darn sure don't have any torque...

Jake!!!!!!

Happy New Year!!!!

How's your Dad feeling? Pretty much over the troubles of last Summer??


gn

Jake, that build with Mahle 102mm thick-wall nicasils should give about 200 to 210 ft lbs of torque and be very reliable; the only parts that aren't original Porsche 911 are the case, cams, and crankshaft. With a CR 901 5-speed performance should be pretty brisk.

Aaa Ha. My next question is can 964 heads be redsigned to flow and displace , exactly like a T-4

Of course it would have to be recast from scratch,

Is it worth the trouble ?

I was surprized to hear about the single exhaust valve configuration.

I was under the inpression, that especally on the exhaust side 2 smaller valves would keep seats from dropping out better than one large valve seat.

I've also been told that a rich running engine can drop intake valve seats when running larger valves. The raw gas chills the seat just enough to schrink it, and out it comes.

A 4 valve head design, should reduce the chance of failures.

Barry, 4-valve dual ignition Porsche 911 heads are available but they don't cool as well as the two valve dual ignition heads.

Two exhaust valves means two exhaust ports and twice as much heat to disperse.

Last time I checked Polopolous was casting his own cases for the conversion..

AND the firing order makes an engine that runs like a Harley :-)

Jake, you're out of date. Dean's first engines used a chopped/welded 911 engine case and a chopped/welded 911 crank that had a weird firing order but nonetheless made great power; the new engines are being built with virgin aluminum 4 cyl case castings and a forged 180 degree crank with 911 journal sizes that has the same firing order as a VW type 1 (1-4-3-2).

Yuck !! LIKE a Harley!!!.

Why didn.t they go with carrera type cam configurations ? I like Hogs But those kinda sounds are not to my liking in a speedster.

Barry,

Read George's post. I've read about the 911/4 in Excellence, and it is a very interesting concept. The price of parts is an obvious issue, but there is nothing cheap about either Type 1 or Type 4 parts at the very high end, and I would assume the cost would be in the same ballpark.

Please, keep us up to date George. Even if it's WAY out of my league, I'm glad somebody is doing it.