Wayne's New Engine - Comments Anyone?
 

Okay, I think I've got it covered. Here is the engine I'm going to be building for my 914-6 conversion:

- 3.0 Turbo Case
- 2.7 crank and rods
- 3.2 pistons and cylinders
- 'S' cams
- 3.0L Turbo Heads
- 40 Webers
- 2.7 Distributor
- Headers + Sport Muffler

Explaination? The 3.0L Turbo case has the smaller flywheel end, so it can accept the 2.7 crank and rods. This crank can be used without hassle with the 901, which I am running in my 914. John Williamson (Otto) has run the 901 with his 2.9 engine successfully in the past (I think that was dynoed at over 300HP).

The 2.7 crank and rods are the same as the 3.0 crank and rods except for the flywheel end. I have these handy.

The 3.2 Pistons and cylinders are a Mahle 3.2 "RSR" set that I recently became aware of. It's a high-dome 10.5:1 compression set with Nikasil cylinders. I will shim the cylinders so that I can run it with single plug and pump gas. I could go with an Electromotive HPX twin-plug system, but that seems a bit overkill for me right now (would also add about $2K to the total price, and doesn't seem like a good investment). Also, my tech editor for the book (Tom Woodford) thinks that there might be some twin-plug clearance problems with the trailing arms on a 914-6 (I'm not sure how the GTs did it...)

'S' cams - good all-around agreesive profile camshaft. Should give plenty of low-end power and torque when combined with the 3.2 displacement. I could go with something even more aggressive, but I don't want to sacrifice my low-end torque.

3.0L Turbo heads - these have good port sizes (32/36). I have those twin-plug 933 heads (which will be for sale soon) but I think that the port sizes on those (40+) will be a bit too large to use on this engine (which will be a street motor). These heads should be a a good all-around size for use with this short-stroke 3.2.

40 Webers. For a street motor they should be fine. If it were a high-revving race motor, it might be starved for air. However, I have these, they are rebuilt, and ready to go. The 3.2 is right on the border where you might need the larger 46s, but the 40s should work well if they are jetted properly.

2.7 Distributor. Good, all-around curve for an engine like this. Tom Woodford has built many engines using this particular curve with very good results. Just need to lock the vacuum retard plate inside the distributor.

Headers + Sport muffler. Not sure what size pipes (I'm don't even remember which size I have), but the Sport muffler should be a good addition.

Should be good for about 240-260 HP...

Comments? Questions?

-Wayne

hmmmm Turbo Case Turbo heads..... Dump the webers and the "S" cams... get the CIS and find that Turbo to complete the package :D :D :D :D

There's a pretty good book out called "How to Rebuild Porsche 911 Engines" by some bloke called Dempsey. Maybe that could be handy? :p

yeah, i have a comment .......... HOLLY MOLLY!!!!! can you say "Frankenmotor"?!?

sorry, i don't have the technical knowledge to comment on the engine build, but with 240-260 hp, you will be very pleased i'm sure.

i've never heard of any problems with the twin plugs and the swing arms, the GTs had them and i've seen others. with the turbo vavle covers don't forget to machine the fins down as per the PP tech article. (-:

please keep the 914 board posted with any details on the progress of your conversion!!

regards,

doug waters

I've pretty much got that lot, except:

- sc case and crank
- mfi throttle bodies (bored to 40mm), converted to EFI
- std early 911 exhaust
- I DO have twin plug (964 dizzy).

I have 245hp at the wheels (270hp at flywheel). The EFI (surely) helps, as does the twinplug. Should be fun! Make sure you run some sort of CDI, of course.

I'm going to run the stock CD system that came with the 2.7.

-Wayne

Wayne;
Here's my $0.02...

1) Are you going to port the 3.0 Turbo heads?
You're right -- for a turbo. For a normally asperated motor I think that the heads have the port sizes backwards. You want larger intake port to flow lots of air into the engine and the smaller exhaust port to keep up the exhaust velocity, especially with the S's overlap. 32 mm intake ports will only work up to about 160-180 HP tops in a smaller (2.0 - 2.4) engine. I think that you want intake ports of about 38 mm's. Your exhaust ports should be OK, but some people might suggest a touch smaller (say 35 mm) might be optimal.

2) Could you check my math? With a 70.4 mm stroke and 95 mm (same as a 3.2) bore, I'm figuring that this is a 3.0, not a 3.2. Or did I miss something?

As a 3.0 I'd expect about 240 HP at 6500 RPM from this configuration and about 205 ft-lbs at 5200 RPM assuming that you have adequate porting.

It's a big bore kit for the 3.0 - 98mm cylinders...

-Wayne

Whoops, I forgot some details:

The 3.0L Turbo heads are ported to 36/35 (perfect), and they are indeed twin-plugged (I wasn't told that before). So I may actually run an HPX system on the car...

-Wayne

Have you considered GE60 cams, or one of the other aftermarket profiles? A few builders I have spoken to consider the S cam to be an excellent cam, but outdated by some of the newer designs. Then again if you have a pair of S cams lying around, slap 'em in there, save a good chunk'o'change.

OK Wayne, that makes a little more sense. With the 98 mm cylinders for a 3.2 liter capacity and an S cam, I don't think that the 36 mm intake ports on your heads will be able to keep up with the cam's rev range. Keep in mind that the 2.7RS also used S cams and heads with 36 mm intake ports and it acted like a "mellowed" S. Your 3.2 is going to be taking 18% bigger gulps of air through the same sized ports. So at 5300 RPM your engine will be pulling the same amount of air through your intake ports as the 2.7 RS would at it's peak HP engine speed of 6300 RPM. I don't know how you will be able to move enough air through the 36 mm ports for your engine to ever reach the expected peak HP engine speed of 6300-6800 RPM.

If you want to replicate the 2.7 RS's power curve, you might want to take your intake ports out to 39 mm. If you want your engine's torque curve to look more like an early S's, then you'll want the intake ports out to 43 or 44 mm. You'll also want the exhaust out to about 39-40 mm.

My experienced experts tell me from their experience, the 40s will be way too big for the short stroke 3.2.

-Wayne

By "40s" do you mean carbs, intake or exhaust ports? The factory used 40 mm intake ports on their 3.2's. Were they wrong? For street use I would expect 40 mm carbs to be OK, but maybe marginal. Certainly not "big" for an engine of that capacity and and individual runner intake system. Especially if you are going to be using a fairly rev'y cam like an early S. In regards to the exhaust, OK -- then use 38 or 39 mm. It seems better to err on the side of undersized exhaust ports rather then oversized.

Anyway, I was just responding to your request for comments. Either way, it will be interesting to see how the motor turns out.SmileWavy

bringing this thread back to life....

Wayne, any updates on that motor? Would 3.2 Carrera heads w/ stock ports work well with the 40 Webers?

Wayne, Whats the pin dia of the pistons? Other than that looks solid.

Wayne,

Why not EFI?

More importantly Wayne -- how's it run? This this thread was started over a year ago.

Wayne,
If a person were to buy that engine...turn-key, what would the cost be. My guess is your 3.0 case was that great deal from the man at the swap meet last year?

PS: Did you get my email from the other day ?

Bavaria911

The stock ports are a little big. I've been told by people who built this combination that slightly smaller ports work better.

I bought a Carrera RS clone with a hopped-up 3.0L in it, and I also bought a stock 3.2 for my 914. So, this engine remains unbuilt, with all the necessary pieces in storage - waiting for that day when I pick up that RSR chassis. :)

-Wayne

These pistons and cylinders are designed to work with the 3.0L, which has the same pin diameter as the 2.7 (off the top of my head)...

-Wayne