914/6 2.0 rebuild
 

What is the best "bang for your buck" topend only, rebuild off an original 914/6 motor. I believe the motor is similar to a 69 911T with 110HP stock. You know us 914 owners are CSOB.

Up the displacement with bigger cylinders/ pistions, bigger cams, more compression, and update the carbs and heads to match.

Your budget is your limit.

real /6 with matching numbers? Or non-matching?
Basically 2.0 thru 3.2 they all cost the same to rebuild.
Non-matching for my money I wouldn't even look below a 3.0

Cant do a whole lot with out changing major components. The later 70.4 crank will drop in and add .34L of displacement. Next step is to get bigger bore cylinders 84MM will get you 2.4 or you can bore 84MM to 86 and get a long stroke 2.5
More info:
http://forums.pelicanparts.com/911-engine-rebuilding-forum/575530-2-5-mid-size-six-what-needed-build.html

You could bore case out to use 90mm Cylinders (not best choice with early case) to get a short stroke 2.5

With either option you will want to change cams as well.

So steps:

Step one send case off to machine, add squinters, case savers and oil bypass
Swap 66MM crank for 70.4
Replace P&C with 84mm or 86mm and appropriate pistons
Replace Cams with E cams
tune carbs for bigger motor
This should give 2.4 E power (160HP) or better nd engine will still look stock from outside.

None of this is cheap by the way.

option B
Sell real 914-6 and buy clone that's already done for half the price.

john

Yep...nothing about these engines is cheap, figure out a budget...then double it.

4-5 years looking for bargains, parts and core I was over $10K and I'm an engine shop, all the labour was "free".

And the NIB webcams I scored just bit me in the bum, another $1k at least.

FWIW. Many years ago I put 90mm P&Cs on my 2,2 T motor making it a SS2,5. I changed the cams to Es. A little porting and Weber tuning and it put out +180hp. Stock 66 crank, case and the heads needed to be bored.

It was, is, a sweet running motor.

Ollies has a web site with all the numbers for machine work. $$$$

As mentioned, if it is a numbers matching 914-6, all bets are off.

Thanks for the reply. Its not a real 6,it's a conversion with a 914/6 motor.

150-160hp would be nice, nothing crazy here. What do I need?

914/6 engine
 

Porsche did have a rally version of the 914/6 with smaller port heads. I don't have the exact numbers in front of me, but they are easily found. For street, you want something drivable (not 6-8k power range)

Basically you will need to increase your displacement in order to have more power without running to 8k rpm.

Which will it be? Bigger cylinders or bigger crank? Or both?

You can have your cylinders bored, although the iron cylinders have their limits. Then you need matching pistons. Shoot for 9.5 -1 CR, unless you want dual ignition.

Or bore the case and heads to fit 90mm P&Cs for a SS2,5.

Or swap in a 70mm crank and rod set, assuming you can reuse your cylinders and have a 2,4l.

You will need to have your cams reground, IMO T cams will limit you.

You will also have to upgrade your carbs to match the motor's potential.

You may want to start a spread sheet to compare all the possibilities. And start shopping for parts.

unfortunately your 2.0 914 engine is just not a great place to start. It has the 2.0L heads(not great chamber shape) and small valves,and no oil squirters. Might be better off selling the existing engine if its a factory 914-6 and purchasing a later 2.4 to build as it has it has better heads with bigger valves, longer stroke crank, stronger case, bigger cylinders etc.
2.2T was 125hp
2.4T was 140
2.4E was 160
2.5 with E cams should be around 175.
I have a engine that started as 2.4T. It has 2.4S pistons, E cams, mild port on heads and runs MFI. Dynos 145HP at the wheels (assuming 15% loss around 175 at crank)
Probably need to factor in front oil cooler at higher HP as well.
That said probably the cheapest thing you could do would be get a set of bored cylinders from EBS (86mm) with JE pistons around 9.0 to 1. I believe you will need to machine the heads for the larger cylinders as well. This would give you a short stroke 2.3 and around 125-130HP. Probably looking at 3K in parts and machine work if you do all the labor and don't run into other things that need attention.

john

I think the OP is somewhat limited,any decent displacement bump is out of the question if only a top overhaul, mild street cams ,careful head work,compression increase,larger venturies,etc will yield a small increase but not sure it won't really justify the expensive with such a derated/mild engine.
Maybe sell the motor as a short block as mentioned,buy a core 2.2 or 2.4 and start with a better building block,my choice would be the later 2.2T but best choice would be a 2.4T.
My 2.2T goes well enough in my 914,is about $$$ and how far your go.
Good luck.

My 914/6 conversion I bought 3 core engines, 1st was a 911 2.0T (same 69T as the 914), 2nd was a 2.7 and I settled on a 3.0

2.0 T isn't the best engine, poor head design, small ports, mag case that costs to redo right, pump not the best, HP mods gets into it being a peeky power band that's not the best for normal street driving. Pro the flywheel is made for the 914 (901) transmission.

2.7 same mag case prep cost as the 2.0, some engines had overheat issues in their past life, cranks have been known to fail at flywheel. Can use the same 69T fly/clutch for the 914 transmission, but this clutch is reaching its limits at 180hp. I'd use the 911 fly and the KEP kit like on the 3.0

3.0 stout engines, alunimum case, strong rods, 180hp stock CIS or up around 250hp possible. Con head studs (divalar) issues, valve guide wear slightly higher, in a 914 needs a PP/clutch conversion (KEP kit)

3.2 with the motronic is one of the best conversions. same pros as the 3.0, except weaker rods (ARP rod bolts required). Con the cost is now pretty high for a good engine, needs the KEP kit.

I'd do a lot of research before I'd jump in, you're building a conversion, who cares if it's a real 914/6 engine.
Personally I'd sell it to a guy with a real 914/6 and use the coin to by a 3.0 -up. I made my money back on the other 2 cores I bought.