dave964diver

Hi all Im just about press order on a bunch of stuff from the states.

I currently have a 964 c2 with the dodgy Cylinder head leaks hence the upgrade.

The Plan is to have a road car that keeps driveability but hike power and torque to around 300 BHP

On order will be

4 litre P&Cs from Ln engineering
Single pulley conversion from clewet.
964 sport cam from ebs
Arp rod bolts
Arp head studds
Master rebuild kit

Car already has a lightweight RS flywheel kit
Getting rid of the PS pump.

Im not fiddling with valves as they ae in good nick and I think the general consensus iis that the stock inlet valves are more than large enough.

My question is before I press order, have I got the right Cam or should I go for something a bit more aggressive. (Im not after a race car)

Cheers All,

Dave

Barty964rst

Dave,

You should check out the Total 911 article a few years back (probably 5 years) on a RHD 964 RS that had a Neinmeister 4.0 conversion done. From memory the power was a little on or off and the project needed some further testing to get a tractable 4.0 964.
The revisit article didn't get completed and the project was delayed.
I expect Colin Belton will be able to shed some light on the project.

race911

It's much more than ordering up a bunch of parts. I'd absolutely, positively, comprehensively talk to one of the experts about the larger-than-3.6L engines. Guys who build and stand behind engines, not just sell parts.

Marc Shaw

I'd suggest Pauter or Carrillo rods too plus uprated valve springs and retainers (like Jerry Woods).

Marc

FeralComprehension

Also, from reading the 911 Engine Rebuilding forum on that other forum there's been some negative press regarding the ARP head studs. Do your own research.

IMO, you shouldn't need to stray too far from the current displacement to get to 300BHP; your money would probably be better spent on uprating your engine managment instead (and note well that this is likely to be required by a 4.0 anyway...).

Luck! (....and prepare to make with the checkbook )

NineMeister

May I suggest that you read Camlob's experience with his 993 engine before making any firm decisions:

https://rennlist.com/forums/993-foru...tec3r-etc.html

That said, in my view there is no point in doing any upgrades to the 964 motor without considering an engine management upgrade as priority number one. Once you have the management/injectors to handle an increase in power you then should decide the intake system that you will run and design the rest of the engine to make the most of that choice. Stock intake will limit power to below 7000rpm, therefore mild sports cams & maybe a 3.75 upgrade is as far as necessary to make a nice tractable road package.

As for the 9m 4.0 litre, the 1000-2000rpm issues were eventually pinpointed to a pair of poorly machined prototype high lift race camshafts which had dissimilar timing between the left & right banks. Just goes to show that even if you think you know what you are ordering, you can still be sold a pup....

dave964diver

Thanks for the replies. Hi Colin I spoke to one of your colleagues today. I would like to fit motec at a later stage(Hence getting the machine in Cylinders) but for the minute I just want a torquey engine and as there is no difference btwn the 4 and 3.8 PCs I think its a no brainer.
Im not looking to raise the rev limit of the engine (Hence not uprating the connecting rods and only the bolts) and Im only replacing the cams as one of the lobes is quite badly pitted and scoured. Therefore a DC21 cam has been suggested as well as a 964 sport Cam. If you can suggest a better suited one I would appreciate.

The engine already revs pretty freely with the RS clutch and flywheel so im hoping this doesnt change too much with the new PC's.

Cheers,

Dave

NineMeister

Dave,
All makes sense, however the engine will run seriously lean with the stock Motronic, especially if the compression is above 11:1. Secondly make sure the dome design of the larger piston is fully optimised for the twin plug 964 head because a combustion efficient 3.75 will make more torque than a less efficient 4.0. Oh, and don't forget that you have to bore the cases for a larger cylinder whereas the 3.75 can be supplied as a slip-fit with 107mm spigots.

A 3.75, on the 9m Motec system fitted with 9m Sport cams & rebuilt/mildly ported heads makes around 360-370hp on our dyno depending on exhaust configuration.

dave964diver

Cheers Colin,

I'll make sure all the above is attended to. Im Getting Equal length headers fitted by Turbo Thomas and Im mildly porting the heads. IHopefully this will increase flow, but as you say they will be running pretty lean. Hopefully I can remedy this with a WS remap until I can afford bigger injectors etc and a motec upgrade. Ill post some pics when the bits arrive.

Dave

evoderby

Dave, although I can understand your reasoning in spending money on a 4 litre kit rather than 3.8 at similar money....

.....as others have said there comes more to it than slapping together some individual components and hope for the best.

Some very experienced people have responded to your post, yet you seem to ignore their advise and only seek confirmation of your personal choices being ok in fact. The above is typically human.....as well as a recipe for disappointment if not disaster.

dave964diver

On the contrary, I haven't ordered anything yet. I have a very experienced Independent putting it together with me. Im just trying to make an informed objective decision. There are many experts with vastly differing opinions. Therefore I am hoping my post will facilitate one which provides a favourable outcome for my needs.

My initial question was about cams btw.

NineMeister

An engine is a complete system, not a collection of individual components, so there is no definitive answer to your initial question. An optimal choice of camshaft can only be determined by the engine builder who has tried the exact combination of parts that you intend to purchase and worked out how to get the best from the system as a whole.

However on the point of engine builders, there is a distinct difference in an engine builder and an engine assembler. As I read your question, it appears to me that what you are really saying is that because your experienced independent cannot advise you appropriately you may want to consider working with someone who has actually worked on similar combinations and thus is prepared to advise you of a suitable cam choice and accept full responsibility for the performance of the resulting engine that they build.

As a big hint and without wishing to question your judgement on the parts you think will work, if you asked me to build you an engine for purely road use I would not consider using a bore diameter above 103mm, but would probably recommend using 102mm as the most reliable & cost effective option.....

Nickmysta

I recommend talking to Geoffrey Ring - I believe his 3.6 pistons produce more torque than the 4.0 LN kit (I guess it also depends on a number of other variables).

One thing's for sure: he stands behind his product. I know for a fact!

dave964diver

I fully understand that an engine isnt a some of its parts. Im just trying to ensure my combination will provide a good basis for future improvements.

Necessity means I need to replace the PC's and the cams. Going to 3.8 or 4 is only marginally more expensive than the stoc PCs so this proved to be a no brainier. Increasing displacement will increase power and torque- provided you cn provide the fuel and air from what I understand.
Now if the stock injectors arnt up to the job ie they can provide for the displacement upgrade then the cylinders will run lean and provide me with none of the above. Id like to get motec fitted at a later date when I get the boss lets me spend some more.

Therefore Im just keen on the best package that will provide a torquey 300 bhp road car with no issues for the min. Im not looking for massive figures colin as Im not tracking the car. I can see youve experimented with countless of these engines and if I didnt have to replace the PCs believe me money would have been spent on motec instead,

Cheers,

Dave

NineMeister

Dave, I totally appreciate your position and agreed, it makes perfect sense to do everything mechanical in one hit.

I can't agree that building a 4.0 will cost the same as buying a new set of factory 3.6 p&c's though, you will have to add the cost of a full engine rebuild, case machining & head studs to your list which will all cost an extra £1500 by the time you are done.

In respect of displacement change to torque increase, all is not as simple as it seems. Torque is a factor of cylinder fill and burn efficiency and unless designed correctly larger pistons can actually have a negative impact on both....

My recommendation is to run a 102mm slip-fit at 11.5:1, (properly) ported heads with 993VR valves, Sport cams/valve springs/ti retainers and tune it on a 9m Motec system from the get-go - but you probably knew this already.