906/Carrera 6/911R motors - characteristics

There are a few of you on this BBS that own the above mentioned cars (any variant of the 2 liter, twin plug, 906 cammed motor). What I am interested in getting is a nice, first hand description of what the motors are like in these cars. I've been going back and forth with Tadd trying to abstract what these motors are like, but all we have is conjecture.

From idle up to redline, I am curious. How does it behave in traffic versus on the track; do you have to slip the clutch a lot? Would you even attempt to drive it in traffic? Does it even idle without serious bucking and popping?

I have wanted to build a 906 clone motor, but would really like to hear how drivable these motors are on the street. From there, I believe I could comfortably make a decision on configuration.

If you guys have one of these cars, please indulge me with a description of how the car behaves. I might even be able to muster up a cigar in thanks.

I can provide you dyno results:D

Kenik:

Having driven quite a few 2.0 race motors with 906 cams and all that, there is no way I'd ever call such combinations anywhere near streetable. :) :)

Now, I realize that many folks have differing opinions about what constitutes "streetable", but this setup comes in last.

Now, take all those components and install them into a 3.4 to 3.6 and it becomes a docile, easy to drive, street motor that still pulls hard to 7800 and can be raced. Even a good 2.8 with a 906-type cam is FAR easier to drive,....:)

IMHO, small-displacement, powerful engines with race cams are simply not fun in any kind of traffic.

Hi kenikh,

I just joined the registry and have posted a picture of my 68 TR on the show my ride thread. I bought the car 4 years ago when its original 901/02 engine was installed. This had the factory rally kits 1 & 2 but still had S cams, 40 IDAs, S port / valve dimensions and single ignition. As chance would have it I then came across a genuine 901/20 engine that had been taken out of a 906 prototype. The temptation was too great and I embarked on installing it in the TR. What seemed like it should be a fairly simple exercise ended up taking a year to complete. For example one thing I had forgotten was that 906 engines were installed the other way round so the throttle linkages, inlet manifolds, timing chest covers and tinwork all need replacing. Anyway we ended up rebuilding the engine from scratch and the anticipation of driving it for the first time was immense.

Am glad (and relieved) to say that the result was spectacular. After running the egine in carefully for 500 miles I took the car down to Classic LeMans in 2004 for its first outing. Although I was still limiting myself to 6,000 revs the gain in power and torque over the 901/02 engine was very noticeable all the way through the rev range. The engine was also remarkably tractable - it would pull cleanly on full throttle from 4,000 and if you were careful with the gas was quite driveable between 3,000 and 4,000 in traffic. Needless to say it was happiest with the throttle wide open and the exhausts blaring! I drove it round the full LeMans circuit during the parade laps before the racing started and the noise of the megaphones bouncing of the main grandstands on the pit straight had to be heard to be believed! I have a bit of in car video which I will try and see if I can post somehow (any tips anyone on how I do this?).

The engine now has about 2,500 miles under its belt and has freed up nicely. I've had it dyno'd at c.210hp - we didn't ring it's neck to find out exactly how much it would produce at the top end but the power curve was still near vertical at 7,750 and it should run to 8,200 or more. Because of the lighter flywheel and internals the engine loves to rev and consequently it is easier to drive as it was intended - flat out. Having said that it is quite happy in traffic and only complains if you try and run on part throttle below 3,000. The only situation it becomes difficult in is when the car in front is doing 25 mph - too slow for 2nd gear and too fast to get the 901 box back into 1st without a very nasty noise!

I had some trouble initially with setting the IDA46s up. It is running with small jets in the interest of driveability rather than ultimate power. It is also worth mentioning that while the engine has 906 cams and 906 valve sizes the ports are 911S dimension. This just happened to be how the engine was configured when I bought it but this combination seems to be responsible for producing better tractability than the 901/20 is known for. I have a friend who has driven my car and a 911R and he noticed the difference.

I could ramble on for hours but in short I have no regrets. The 901/02 engine was great but the 901/20 is in another league altogether.

Best regards,

Philip

OliveR what are those collectors going to the megaphones???? Heater boxes or some trick exhaust?

Kenik, My current application is a development of the 906 for racing only. Its awesome above 5500 and basically makes no meaningful power below it. It idles nicely at 1000-1200 but (due to the lightweight flywheel) you must revúp and slip the clutch to get it going. Judging from that I'd say that perhaps you can tame the beast by using a heavy flywheel to providde torque buyt you'll loose the fast spiinng nature of the beast (at least a bit).

I guess that Philip's car perhaps has a stock flywheel to compensate and thus provide the driveability he mentions.

My prior engine was a "stock" 906 spec and was more tractable than my current engine but it was still peaky and not for everyday driving. Again I had a light flywheel...

Perhaps John can chime in on the effects of the flywheel and how much it could compensate for what he and I have experienced on race engines.

Remember, with these low displacements, high revs are needed if you want to make power.

Cheers, Juan

Fantastic car Philip !!!

I would agree with Steve as far as a C-6 motor with an ultimate race tune...

However, after driving Stephen Childs T/R for 4 days in '04 I would completely agree with Philip....

This car was initially well set up for long distance rallying by the Swedes ... then FIA raced through the early '70s... then brought back as a vintage rally/touring car by Mark Waring...

It's set up is for speed, tractability and long distance comfort... and it doesn't disappoint

I would have to talk to Mark, but I would imagine that cam and ignition timing have been pulled back a bit, and the 46's choked down slightly..... But the result is still brilliant... Sure, you have to keep the revs up (asspeshelly driving with a passenger) ... but once you 'get it', the rewards are wonderful...

The car will idle, pull smoothly at low RPM, and SCREAM when you want it to.......

And Oh that scream.... There's nothing like in the Porsche world...
In my estimation the quintessential 911 symphony with about 4 different octaves all the way to 8000...... :eek:

Cheers Philip and welcome... and please more pictures... :)



The Childs Gulf T/R then and now...

I didn't expect to get so much feedback, both on the thread and in PM! :D OliveR, your dyno runs would be interesting to compare to these:

http://www.early911sregistry.org/for...highlight=dyno

The reason I asked for impressions is that even though I have seen the dyno figures, the vast hole below 4000 RPM left me wondering what the car behaved like in lower RPM range. Additionally, nothing beats a narrative, seat of the pants assessment, IMO. I think you guys have answered that.

BTW, the comments regarding the 901/20 motor with 'S' ports is more than I could have hoped for. Having these data points is invaluable. Now I am curious if anyone has MFI vs. carbs opinions and thoughts in terms of the driving experience.

Keep them coming. :cool:

My '75 Carrera street/track car came with a 2.8 twin plug. 906 cams, 46mm Webers, twin plug & ported heads, 2.8 RSR pistons with the tops cut down to lower compression, 90mm Mahle barrels bored to 92mm, Electromotive HPV-1. 221 rwhp. (254 @f/w) & 185 max torque.
On the street, the motor wasn't very happy, and didn't come alive until 4500 rpm and pulled to 7500 rpm. Starting it was a ritual. The problem is most of your street driving is in the lower rev range. After finding a few pulled head studs I went with a 3.4 twin plug. Even though the 3.4 is set up for racing, it's much easier to drive on the street.
I've sold off most of the parts, but still have a '73S case bored out to 92mm and the twin plug heads if anyone is interested.
Harold #334

Here are some pictures of my 901/20 engine after it had been fully stripped. I particularly like the titanium conrods - they were almost too nice to put back in the engine!

Depending on you intentions there is no substitute for cubic inches at least for a street motor. I have a 2.8 in a track 911, even this motor doesn't wake up until 5000-5500 rpm, it likes 6500-8000 even more, is is a little bit of work keeping the revs in the powerband. I have a 3.5 in a street car, it could care less where the revs are, pulls from 2k-8k like a train. I know the vintage 2L guys are getting very big HP from 2L motors, I have heard as much as 270 +, may be all BS. But these are high strung and expensive grenades.
Phil

[QUOTE=ErVikingo]OliveR what are those collectors going to the megaphones???? Heater boxes or some trick exhaust?

These are our 906 SSI repro megaphones,no heater boxes,see pics of originals i've found.

I am interested in the case and Twin plug heads..

call me at (310) 456-8833 or Email to execmalibu@earthlink.net..

Thanks

Jeff

My intentions are to build a very hot but streetable 2.0. I consider the 'S' cam too mild for my tastes (I know, I am sick) and find the low end characteristics of the 'S' cam too much of a compromise toward streetability. I could deal with more finickiness from my motor on the low end than the 'S' spec motors. Off the line torque is for sissies. ;) I realize my definition of streetable might be different than most people's. RennTyp's posting pretty much summed it up for me.

Quote:

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Originally Posted by pu911rsr

I know the vintage 2L guys are getting very big HP from 2L motors, I have heard as much as 270 +, may be all BS. But these are high strung and expensive grenades.
Phil

---

270+ sounds like BS to me too (and I know as I own one of those hand granades...). Try 20-30HP less than that depending on how many hours and other minor details :cool:

Have to second Chuck's observations about Steven's S/T...

Drove it for a bit last summer and was blown away with how good the small-displacement motors can be at a high state of tune. For me, it was a real eye-opener because I (personally) tend to prefer the preference characteristics of the T and E motors over the S on the street.

Childs' car is a BLAST to drive, maybe the best set-up early 911 motor and chassis I've been privileged to drive. It just FEELS good...I walked away thinking that someone, somewhere had spent a lot of time fettling that engine -- perfectly.

Now, I think a lot of that car's satisfaction is derived from the gearing, which should probably be addressed here, too. My guess is it wouldn't have been nearly as keen, bright, and speedy had it been saddled with normal street gears...

But I am working off memory here. Steven?

pete

Ed,

You're absolutely right ... the gear box matches the performance and manner of the Gulf's T/R motor perfectly

If I remember, Stephen's gearing is very 'close' but not too 'short' ...

Like everything else on the car it's very well sorted out... and probably took a bunch of development time to do the job that well...

Cheers,

So a question for Stephen then: what are the gears (letters) are you running? Inquiring minds want to know.

Chuck,
How much does Stephen's S/T weigh? Might have a bearing on the perceived power and response. I'll wager it's lighter than stock. :)

Sherwood

Gearing and weight are definitely at work here. I suspect it's a lot lighter than most early 911s. I'm guessing -- and only guessing -- it starts with a 2 and a 0, maybe less?

Steven mentioned the weight of the car that day, and I remember being impressed. That particular S/T is silly good to drive. Back to back with Carrera GT and no disappointments...

Am I conveying how much I like that car yet?

pete

Here is some printed info on this motor. Boschen, Lothar and Jurgen Barth. THE PORSCHE BOOK: A DEFINITIVE ILLUSTRATED HISTORY. 1978. Argo Books.

906 Carrera-6 Engine (901/20) – p. 445-46:
engine weighed 119 lb. less than the stock 911 engine
crankcase was cast in Mg instead of in Al
flywheel was lightened from 6 kg to 3.5 kg
Ti connecting rods were used (440 g) instead of the forged steel rods (550 g)
Mahle pistons were Al alloy forgings, and the light alloy cylinders had porous Cr plated bores

- What I want to know is how did they take 120 lbs. off of a stock motor?? Was it just the flywheel & heat exchangers or were some special wt. saving ticks used internally? The conn. rods save some wt. but not a huge amount. The items listed in the text above just don't add up to that big a wt. reduction.

magnesium vs. aluminum case accounts for the bulk of it.

After driving Schmidts 2.2S before and after gears (A,E,I,N,S) I finally understood what short gears do for performance, and fun. On the small engines, it just makes a different car. The photo is of the transmission Gordon Ledbetter just finished for my '67S. I bought the last NOS aluminum 901 case Gary Emory had, and put in A,F,J,O,S. This is airport with the exception of first. My fourth is now fifth so she's no longer a highway cruiser, but that's okay.

Kenikh, Since your box already needs an overhaul, I'd consider gearing that thing now, and have some fun while saving up $20K or more for a special motor.

Quote:

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Originally Posted by tfiv

Kenikh, Since your box already needs an overhaul, I'd consider gearing that thing now, and have some fun while saving up $20K or more for a special motor.

---

You read my mind, Tom. The box is going to Bernie in September after the summer season ends, so he told me to plan now on what I want to do. Wanna hear something else that's beautiful? My car is an early enough '69S that it still has an aluminum 901 case, numbers matching, of course.

BTW, are those the gears you ran to Sonoma?

Kenik,

That's a good question ...
If I remember, the Gulf car's documentation is very elaborate without being very specific ...

Sherwood,

I think the car is just under 2100 lbs.

Ed,

I to have had the privilege of driving them both ... and I think the experiences were equal for VERY different reasons.... ;)

Cheers,

Kenik, right on! No, the original 901/02 was, and still is in the car (not for long). Since I will be turning about 4700 at 75MPH and hitting the rev limiter at 115, 8 hour I 5 trips aren't in the plan. I'm going to put more reasonable gearing in my larger displacement hot rod. Between this site: http://www.geocities.com/z_design_st...n_993_bit.html and the gear chart on Rennlist, you will be able to squander hours of your employer's time geeking out on potential gear set ups.

What's the type number on your box?

Quote:

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Originally Posted by kenikh

My car is an early enough '69S that it still has an aluminum 901 case

---

Kenik I agree that the early cases are cool looking. However, if you are eventually going to put a big motor behind it and you want a limited slip, they present some problems. You have to use the 904 style slip which is very hard to find. You also then have to use the unique drive flanges etc. Anyway, you might want to find a mag case core for your special box, and set the original on the shelf. - Tom

Hello: The 906 cams are not the way to go on a street car. If you think the S cams are too mild then try some modern grinds that work better than the S cams and are more streetable. I would do shorter gears for sure. I tell everyone that if want more drivable power get the right gears. For every $100 in gears it will cost you $1000's in engine work. I would also use 40 ida's or mfi on a 2.0 street car or better still efi. I used to run a 2.0 engine with twin plugs,906 pistons,911 biral cylinders,aluminum case,large valve heads ported, and modified S cams. This engine would pull away from 906 type engines unless it was a long straight on the track but by then the next corner came up and I was gone. Gears for a street driven car try A,F,N,S,X. These are easy gears to find. I would also build up another gearbox and keep your stock one for a spare. You can never have too many spare tranny's. If you need gears or boxs I have some and also some 2.0 race stuff. My favorite street engine for an early car is a short stroke 3.2 with a short gearbox and 7x15 rear wheels. This is alot of fun to drive and very fast! Thanks Eric

Eric, please send me a note with the 901 gears you have that you'd be willing to part with...

Quote:

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Originally Posted by Eric911S

Hello: The 906 cams are not the way to go on a street car.

---

You actually hit on my next point: I want 906 top end with the faster ramps and subsequent better drivability of a modern cam. I figured the 906 was the perfect baseline; everything newer would be gravy in the drivability department.

BTW, if you guys want some serious 901 gear crack, try the enclosed and zipped Excel spreadsheet out.

Quote:

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Originally Posted by tfiv

After driving Schmidts 2.2S before and after gears (A,E,I,N,S) I finally understood what short gears do for performance, and fun. On the small engines, it just makes a different car. The photo is of the transmission Gordon Ledbetter just finished for my '67S. I bought the last NOS aluminum 901 case Gary Emory had, and put in A,F,J,O,S. This is airport with the exception of first. My fourth is now fifth so she's no longer a highway cruiser, but that's okay.

---

Using the calculator, I am thinking A,E,J,P,W. Perhaps I need to start another thread: "How common are gears for the 901 (by letter)". Oh wait, I just did!

http://www.early911sregistry.org/for...8579#post88579

Kenik,we have specifics 906/RSR cams(more torque) and 906/R PC's:)

I will try and answer some of the questions on my T/R.

Here are the details according to the orginal paperwork and the orginal mechanic who looked after the car, and neither the engine nor transmission have been opened.

The 2.0 engine has the magnesium crankcase, twin plug heads, 906 camshafts, forged crankshaft and titanium rods ie 906 type engine. It now has 48 IDA webers, though I believe it orginally had 46's. it also has a stronger clutch and lightened flywheel. It is red lined at 8400 but will go beyond as it does not have a rev limiter!! The exhaust is the factory sport three outlet with side one blocked off for street use as I have lost the other cap, officer!!

It drives like two engines, below 4800-5000 it runs similar to a 911S and then almost runs as if a turbo come-in, it just takes off to the redline! It can be kept in the hot zone without a problems. It is no problem to run in town.

The document on the transmission state it had airfield gears but is not specific to the letters. These are ideal for the engine although due the gearing it runs out of steam at 130mph but it fun getting there??!! It also had a 80% limited slip which was giving problems. I had it overhauled and it is now running at 40%.

The weight of the car was 2056lbs in 2000 with a full 100 liter fuel tank and oil.

Part of the great handling is the car is running on 7 and 8 X 15". It has also been corner balanced. The shocks are standard vintage bilstiens.

As has been written in previous threads it fun to drive and is not any problems to drive in town and then open it out. It can get slight plug fouling after a lot of town driving which is quickly cleared with some spirited driving. On my favourite local road(test track) it feels about the same power and out handles my RS LWT.

Hope this helps.

Stephen

Thanks for the clarifications Stephen ... ;)

And we won't even mention how you could charge admission just to hear the whole rev range from the passenger seat... :eek: :p :D

Cheers mate,

"...The weight of the car was 2056 lbs in 2000 with a full 100 liter fuel tank and oil. ..."

Stephen,
Thanks for the vehicle specs.

That works out to be about 1845 lbs. with an empty tank and about 1950 w/half a tank (13 gal.). Nice.

The light chassis, low gearing and relatively high compression ratio (10.3:1) are great equalizers for the top-end strong 901/20 engine. The factory did a good job with packaging, something we should strive for to maintain the correct balance.

Kenik,
Unless you can replicate the S/T specs, I think you might be less dissapointed with a relatively torquey 2.7 in a primarily street-based car. Unfortunately, Porsche stopped development of the 2.7 before they could insert the various 901/20 bits inside. However, the 2.8 and 3 liter versions yielded 300+ HP and +200 ft.lb torque to indicate what happens with more cubic inches.

Sherwood

Howdy all:
I have been following this post like a giddy school girl... thank you to those who have taken the time and shared.

I finally have a question. I was rereading the tiny section in Paul Frere's "Porsche 911 Story" and wanted any additional info people could give since I have a 67 to play with and this seems a touch more 'period correct'. Here is the section from page 177 (ISBN 1-85260-128-0):



For the 911T and 911S, a racing engine was available, differing only in detail from the full racing engine used in the Carrea-6 sports-racing car. The main differences were that the standard ignition system was retainted and that the valve sizes remained standard, as required by the rules: 42 mm intake (Carrera-6 45 m), exhaust 38 mm (Carerra-6 39 mm). Carrera-6 camshafts were used with the following timing:

Inlet opens/closes 104*btdc/104*atdc
Exhaust opens/closes 100*btdc/80*atdc

as well as the Carrera-6's Webber 46 IDA 3 carburettors and appropriate larger diameter inlet manifolds, Carrerea-6 pistons with larger valve pockets were fitted and the compression ration was raised to 10.4:1 by machining either the cylinders themselves or the heads. The cylinder head ports were, of course, bored out to match the larger intake manifolds and the racing exhaust system which was part of the modifications. A lightened flywheel and reinforced clutch assembly were also fitted and for the 911T only. Except for sprint racing, an oil cooler was added in the scavenging circuit and located in the right hand front wing; it later became standard in the production 911S models.



I guess the first question is if this 'spec' is accurate as layed out by the author and what was the developed power? Second would be if the titanium rods were used or if the lightest weight steel rods were (540-560g -which is just about the lightest steel rod I can find)? Finally (for the short term :D), what are the dimentions of the 'larger C6' intake manifolds? Looking at a 45mm head to my right, the valve bowl is only, maybe, 37 mm so there must be some taper to the port assuming the C6 intake was matched to the intake and was 38 mm.

Thanks in advance,

tadd

48 IDA?? Really? Wow....

Quote:

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Originally Posted by stchilds

It drives like two engines, below 4800-5000 it runs similar to a 911S and then almost runs as if a turbo come-in, it just takes off to the redline! It can be kept in the hot zone without a problems.

---

Did you mean to specify a 200 RPM rev range or is there a typo in there?

Kenikh,

I think Stephen meant that the car is different from idle to the 4800-5000 range ... then UP from that it takes off 'like a turbo' to it's 8400 (or God know what) limit...

BTW... I found that a 'conservative' 7800 to 8000 was plenty to get the job done in this great little car... ;)

Cheers,

I've never heard of 3-barrel 48 IDA's before & didn't know they existed.

Any pictures Stephen ?

I was going to make the same comment, I thought the 48's were 2 throat carbs. I know people bored out carbs to make them bigger.
Phil

Ok, they are 46s. I went out and checked the car. When I wrote up the specs I used the FIA document issued for the car in 2000, it indicated the 48s.

Hope the inspector is not reading this tread!!

Stephen

Another request: Does anyone have photos of the underside of a 911R motor showing off the exhaust headers in addition to the megaphones (which Oliver was nice enough to already post). What is the header diameter, are they equal length and what is the length of the primaries?
Thanks.

One more thing; did these cars use a magnesium oil pump like on the standard cars?

There is an unstamped 911 2.0 liter sandcast engine that I saw in a warehouse on Friday. It may be available for sale but no promises and it is NOT mine.
The engine is dual plugged with correct Marelli distributor. It has Ti rods, 46mm Webers with correct manifolds. There is a factory lightweight flywheel/pressure plate assembly installed as well. Oil cooler, oil lines intact.

I think a full factory "R" exhaust system could be had to go with it for a sum.

The engine is fresh.

Tom

??????????

Quote:

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Originally Posted by ErVikingo

??????????

---

????? :confused: ???

Tom

Who, where, what and how much ?????? :cool:

Quote:

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Originally Posted by RennTyp

The engine now has about 2,500 miles under its belt and has freed up nicely. I've had it dyno'd at c.210hp - we didn't ring it's neck to find out exactly how much it would produce at the top end but the power curve was still near vertical at 7,750 and it should run to 8,200 or more.

---

So to make sure I read this right and to help in my decision making process:

You dynoed this motor to just below 7800 RPM. The motor has 45mm intake valves and 39mm exhaust valves; the ports are 36mm intake and 35mm exhaust. This resulted in an at the crank HP number of 210 HP on 906 cams.

THE ONLY THING I CAN SAY ABOUT A 906 ENGINE IS IT'S THE ONLY RACE CAR I DROVE THAT I NEEDED EAR PLUGS;THE SOUND ON CAM AT 7000-8000 WAS LIKE A BANSHEEE SCREAM,MIND YOU I'VE DRIVEN 550A,904,A STANDERED 906,CARRERA SPSTER GT,ELVA PORSCHE,AND SOME OTHERS(I WILL NOT MENTION THE FERRARI RACE CARS) I've forgotten;there is no sound in the world like a 906LH on cam.BOY I MISS THAT CAR

What is LH?

Langheck

Means "long tail" in German. There were two 906s: the short tail and long tail.

Thanks.

What type of heads did the 906/Carrera 6 engines have?

They had the 2 liter deep dome head profile and 38mm ports. I [i]think[/] they had 45I/39E valves like the '69S heads, but they might have been smaller. If so the only difference between the 906 and '69S heads would be the ports and twin plugs. Some had MFI ports, some did not.

With the exception of a 906 Mag Crankcase and the 906 Mag Upper Valve Covers...

I have the rest of the 906 factory parts so I can build a correct factory motor, several parts are in fact NOS; 906 Center-Lube Camshafts, 906 Center-lube Chain-Boxes and Covers, 906 Mag Intakes, 906 Early Marelli Twin-Plug Distributor, 906 Ti Rod Thrust Bearings, 906 Flywheel, 906 Clutch Disc and Pressure Plate and a set of 906 Cylinders to name a few. This is the results of many years of collecting all the right parts.

Can anyone help me source a pair of OEM 906 Mag Upper Valve Covers? :rolleyes: I gave up on finding the crankcase.

I can be reached directly via email at AJSERRANO at MSN dot COM. Thank you for your help.

PS: Recently I was fortunate to sourced a pair of 906 Mag Lower Valve Covers, the 906 Motor Mount and Twin Marelli Coils with Ballast Resistors. Below is a nice pix of a 906 motor recently taken at the Collier Museum.

Attachment 454853

Attachment 454852


906 Mag Valve Covers recently sourced.

Attachment 454854


906 Mag Motor Mount recently sourced.

Attachment 454855

906 Marelli Twin-Coils

Attachment 454858

I also have the 906 exhaust, very cool pieces indeed--and they fit my 914-6 GT for that real authentic 906 sound! :D

Attachment 454857

Here is a sample pix of the 906 Mag Upper Valve Covers I'm missing. Anyone?

Attachment 454856

Thx!

Quote:

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Originally Posted by beginner

Thanks.

What type of heads did the 906/Carrera 6 engines have?

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Some detailed photos of the 906 (1966) Twin Plug Racing Heads...

Bruce Anderson book.

Attachment 455779

906 Twin Plug Racing Head - NOS

Attachment 455780

Attachment 455781

906 Twin Plug Racing Head - Casting Number

Attachment 455783

906 Twin Plug Racing Head - Casting Date

Attachment 455782

906 Twin Plug Racing Head, ATE Intake / Exhaust Valves, NOS (for lash-caps)

Attachment 455784

906 Twin Plug Racing Head, ATE Intake / Exhaust Valves, NOS (for lash-caps)

Attachment 455785

Attachment 455787

Free bump!

These are 914-6 GT Twin-Plug Racing Heads. Same as '906', same casting numbers, but with a later casting date code of 09 69.

The 906 heads were removed from a factory 914-6 GT race motor many years ago.

Attachment 455793

They became available and I made the purchase.

Attachment 455794

Same 906 / GT heads at Ollie's for restoration.

Attachment 455788

Attachment 455789

Attachment 455790

Attachment 455791

Note the casting number and production date. For a 914-6 GT.
The 906 plastic cars were long gone at this point, but their racing parts production legacy continued in other models.

Attachment 455792

https://imagizer.imageshack.com/v2/xq90/924/b9DQ97.jpg

Do you have any detailed dimensions for these valves as we are planning to manufacture the 'solid' rockers later this year and I think that these valves differ from stock valves in their length above the keeper grooves.

It would be good to know as it may be worth trying to source the correct valves.

Valves are approx 2mm shorter, when at my notes I'll confirm. Early and late castings differ, in provisions for air injection and MFI casting boss as models for street and racing advanced. Having rebuilt 3 R drive trains in the last 10 years I accumulated a base of knowledge. Gordon

A few of my measurements with a dial-caliper from a collection of 906 ATE Valves I have.

Keep in mind that these are used valves and the stem may have been ground.
Besides all that, my measurements at the time were done rather quickly, taken only for a point of reference.

Intake ATE 3056 - 45mm / 111mm

Attachment 455809

Attachment 455810

Attachment 455811

Attachment 455812

Intake ATE 3057 - 39mm / 111mm

Attachment 455813

Attachment 455814

Attachment 455815

Attachment 455816

...more to follow.

More measurements, other 906 ATE OEM valves...

Yes, not the most accurate tool, but what I had handy.

Attachment 455817

Attachment 455818

Not my measurements. Ended up buying these valves also.

Attachment 455819

Attachment 455820

NOS? Looks like it to me...

Attachment 455821

Attachment 455822

The top of the stem appears to have never been ground-down

Attachment 455823

PS: The 'lash-cap' valves I believe are actually longer than those used with adjustable rocker arms. Maybe someone else can confirm this.

PSS: By chance, does anyone have a single 906 Mag Upper Valve Cover laying around? Gordon?

Like this...

Attachment 455830

69S valves are like 113mm, defintly longer than lash cap valves. G

Quote:

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Originally Posted by gled49

69S valves are like 113mm, defintly longer than lash cap valves. G

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Well, that answers that question. I didn't have any lose street valves here to compare to the 906.

Here is something some of you might find useful, not 906, but good reference to have nonetheless.

911 RSR Valve Specs (which also use lash-caps).

Attachment 455843

Note the RSR valve length of the Intake (112m) vs. the Exhaust (110mm)

Attachment 455844

Drove R4 on the street...definitely didn't need to slip the clutch, and "banshee scream" is definitely right. I found it to be "steerable," but there wasn't much squirt down low. There was a lot of scream with so-so power (by modern standards) up top. I'd say a 2.2, 2.3, or 2.5 is a better choice for anything other than an original R. They're just better engines in a light car, and feel quite a bit faster to me. Just my take.*

*Then again, I am not sure I have ever heard a scream through the woods like I did as Patrick Long made repeated passes for the camera...

Love this threads !!! ;););)

So it looks as if the 906 Valves are the same length as those used in the standard 901/01 engine which were 111.15 on the inlet and 111.75 on the exhaust.

The later valves on the S engines were 114.0 on the intake and 113.5 on the exhaust and I wonder why unless it is to deal with swivel adjuster changes ?

The Workshop Manual only reflects this change of length on the 2.2 engines but the 'Spec books' show this change happened on the 1967 'S'

I have the part numbers for the RSR valves but can't find any other details.

I will have to set up a carrier and check.:)

Just to help the info:
911R probably cut a little, used, flat face intake
69S new, dished intake
2.2-2.7 used
RSR new, flat face intake

While searching for a pair of the 906 Mag upper covers I need, I found this ��

Attachment 458165

Attachment 458164

And here is the one Mag 906 piece...

Attachment 458168

So the 935 found its covers basic design in the roots of the Carrera 6. Very cool...

I have an original sand cast mag 906 engine case numbered as a spare if anyone is looking for one to complete their 906. Please see my site http://www.Porsport.com Thanks

Quote:

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Originally Posted by 914-6gt

While searching for a pair of the 906 Mag upper covers I need, I found this ��

Attachment 458165

Attachment 458164

And here is the one Mag 906 piece...

Attachment 458168

So the 935 found its covers basic design in the roots of the Carrera 6. Very cool...

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You bought the one on Pelican, eh?

Actually, no. I did leave a question for the poster but never received a response. Someone else purchased those 935 pieces, but it wasn't me...

The race valves are shorter, 70 on stock valves longer than earlier to compensate for changed valve angles I assume.