Porsche Enthusiasts Club Forum

Hi, The company we use to do our cosworth cranks, advised me not to take to much weight off the crank. I just listened to him to be fair as he knows his business.

Thanks for the comment Jon. I've just had a look at your web site and your setup looks rather impressive.
Cheers Tim

Great build, even better to see it done in the UK. Top man for investing the time and £££ in a 944 project. Lots of revs'n'lots of boost! Question is on the long term durability, what do you think? Are you going to put the engine in a car and track it when its ready?

Tom

Hi Tom, Yes the engine is going in a car and yes I would like to do a track day or two. Has for durability only time will tell, but I think the Porsche engine was well over engineered for the power it was running standard, just like the cosworth engine. The engine I used for this build had done 164,000 miles and was still on standard shell, it only needed a re-build due to broken valve spring which caused it to nip up on that cylinder.

Also do you have a contact number and do you mind me contacting you with regards to your ECU upgrade. Look interesting as I am building an atmo 3 litre race engine.

Cheer Tim

Interesting, I just PM'd my mobile.

Tim, did the crank guys say why they suggested leaving it alone in terms of weight? They seem a pretty big crank with plenty of meat on the bone. There has been a bit of speculation over the years about lightening ours. I requested mine to have a medium grind and it came back to me pretty much with a full knife. (That's in the new motor with dry sump which should be fired up again in a few weeks.) Some say to keep a bit of meat on the reciprocating mass for driveability. Perhaps for road cars this isn't such a bad idea.

Re the extractors, I suppose for an extra 800cc's the S2's should be bigger than the 2.2 Cossie's. At least you have that up your sleeve for the future.

I see that you're building an Atmo motor. I also see that you know of Michael Mount. Have you seen his Atmo motors? They look pretty ta$ty! http://forums.rennlist.com/rennforums/9 ... 400hp.html

I thought the capacity was 2.7 ?.

No not really, but its probably on the lines of driveability. I showed him pictures of cranks on Broadfoot Racing's web site and he didn't like the look off them. Yes the cranks are heavy, but it is a 3 litre. We use a Arrows 84mm billet crank in our 2.2 engine and they are noticeably bigger and heavier than the standard crank. I supplied him with a crank, rod and piston and left it to him. The billet crank in the RS200 Evo engine is also a heavy lump. I have had a read up on crankshaft design and it is amazing how much they say a crank flex's. Also how the weight of crank, flywheel and front pulley are important factors in reducing this.

Yes I have read the article on Michael Mounts Atmo engine, an amazing bit of work. I did speak with him about is camshafts, but with import duty and V.A.T they were going to cost the earth. Nice guy to talk to though. The one I am building will not be on that scale, we have to run the original inlet manifold, so it will be interesting to see how much extra power we can gain.

Cheers Tim

Yes it is a 2.7. 104mm bore 78.9mm stroke

Do you have to specify all dimensions on those Arrows cranks ?. In the interests of buying British, and avoiding import duty . I asked them for a price for standard size 944 forged rods, they said there wasn't anything on the shelf and they would have to make them from scratch and wanted all dimensions.

No, this is a crank they design and normally have in stock. If your after a set of rods, there was a set on Pistonheads for sale, in Porsche parts. Cheers Tim

Thanks I've seen them, Devon is a long way though.

Hi
I am building a 3.0 I doing the boring option and using an s2 bottom end with a 2.7 head. Is it just standard cast liners that you used? My nine builder said he uses these on a lot of cars but for some reason some people keep going on about keeping Alusil. I think to get it re coated its about £700 so I would prefer to put liners in if its would work as they would be stronger aswell.

Alusil blocks can be plated with Nikasil or honed/lapped, but machining the block, buying and the fitting liners, and then finishing the liners to suit the pistons will be a lot dearer.

I may be missing the point here Sandy, but Alusil isnt a coating, it is a very high silicone content alloy. If he doesnt know this and know how to vore it then he might not be the best fellow for the job...