Engine Refresh

[GPF]

Hi Pete,

Yes, it is.

I'm pretty sure the rods are cast and yes, I think it's just between centres.

I've just called EMC and they can't rebore our engines anymore, they sold the relevant kit some time ago and now put steel liners in instead.

I've also just spoken to Serdi who can but I think the problem there may be their lead time - currently 12 to 14 weeks.......

Hmmm

 

[924Srr27l]

Hi Pete,

Yes, it is.
I'm pretty sure the rods are cast and yes, I think it's just between centres.
I've just called EMC and they can't rebore our engines anymore, they sold the relevant kit some time ago and now put steel liners in instead.
I've also just spoken to Serdi who can but I think the problem there may be their lead time - currently 12 to 14 weeks.......
Hmmm

What a Pain!, I had a similar scenerio with a 2.5 Block I was buying which then under closer inspection the bores were not that good, so I asked if a 3.0 block would suit the 2.5 Head i'd already had ported for $1000 ! the answer was yes and hence I went for the bigger bore 3.0 block and the 2.5 crank shorter stroke final cc 2707cc 8 valve.

How about this option on the bay ?
http://www.ebay.co.uk/itm/Porsche-944-2-7-Engine-Only-51-185-Miles-Engine-Code-M44-12-/262497720373?hash=item3d1e155835:g:IVwAAOSw3YNXbnBC

It could of course also not be that good once stripped, but it's low mileage and has the bigger valve head...?

R

 

[PSH]

Hi Pete,

Yes, it is.

I'm pretty sure the rods are cast and yes, I think it's just between centres.

I've just called EMC and they can't rebore our engines anymore, they sold the relevant kit some time ago and now put steel liners in instead.

I've also just spoken to Serdi who can but I think the problem there may be their lead time - currently 12 to 14 weeks.......

Hmmm

Damn...that's a bu***r.....I guess word of their work has spread, or perhaps more and more 944's need rebores, I do recall when I visited that they were working on an engine sent from Europe, Belgium IIRC. They also do an awful lot of work on vintage engines including making new white metal bearings, Lambo's and Ferrari mod not to mention classic F1 car engine rebuilds, as you can see they are much sort after from across the industry. It may be worth explaining to (iirc) John where the car is currently ( I believe you said OPC)to see if they have any movement on that lead time, the piston's would probably need ordering in which may take a few weeks coming from Argentina.

regards

Pete

Edit: forgot to say I'd ask them to recheck that rod before condemning it, measuring just between centre's on a worn bush would offset the small end centre, not by much but enough to show...however as you confirmed it's cast then yes it's possibly a little out of shape.

 

[blade7]

Jon Mitchell may have some parts on the shelf to save on the machining lead times. If not he's well connected at Capricorn, if they aren't doing motorsport work at the moment.

 

[SimonP]

Hi Graham
I may be able to help, please pm me..

Simon

 

[blade7]

Another brand new OPC 2.5....

 

[GPF]

Hi,

Thanks for the info guys

Popped in to look at the offending items yesterday afternoon to see what has changed the prognosis.

The no. 2 rod is visually bent - it's very very slight but you can see it's got a curve in it on the thin axis. The rest are perfect. Before we took the engine out the compressions were checked and all were within spec but no2 was about 5-6psi lower so this may be the cause. I have checked them myself in the past and I think that has been the case for a long time so no idea when that happened. It's an easy fix though.

As for the cylinders, there is a very slight lip at the top of the bores. It's pretty faint but you can certainly feel it and whereas they originally thought it wasn't too bad they are now thinking it probably means it warrants some attention.

The pistons apparently have a coating on the skirts and that has worn down in places so there are some shiny patches. No indication of actual wear on the pistons but they recon that the thickness of the coating is a tolerance so if it's gone they must be out of tolerance even if there is no wear to the actual skirts. They did wonder if they could be recoated but if the block does need attention then oversize pistons would be needed anyway so it's possibly a bit academic and it's the combination of these two factors that has changed the outlook.

The crank looks fine as does everything else, although the flywheel is a bit scored.

So, I think I'm probably going to send it somewhere for a proper inspection with a view to honing (or lining) and getting it built up as a short motor. If it does need more than just a polish then probably go for new forged rods & pistons and see what the options are. I don't really want to develop it further, but.......

Thanks for the link R but at this stage I'd quite like to keep the original block/engine number if I can - I know it's not important but I'd just like it to still be a matching/original numbers car.

Hi Simon, how's it going? Still got your email so I'll drop you a line this morning I'll PM you too if I can remember how to do it!

 

[John Sims]

Hi Graham,

Has been so long . With regard to the lightened clutch I was a little disappointed. When Autostrassa fitted mine they said "Thats a really nice clutch ...what are you going to do to muck up the car more?" In fairness it wasn't as bad when it wore in. Initially it was like a switch.

My main disappointment was it wasn't as ziggy as I thought it would be. The lightened flywheel I had in Sluggy allowed it it rev like a motor bike engine. The 944 engine has so much inertia in the other components that the difference wasn't terribly noticeable. That being the case it isn't terribly detrimental either (once glazed in a bit) so my view is you might as well. While potentially a bit snatchy you are going to have access to more performance orientated specifications.

If I remember correctly I went for a SPECS single plate which might have been from Lindsey Racing (when exchange rates were much better).

 

[924Srr27l]

Hi Graham,
Has been so long . With regard to the lightened clutch I was a little disappointed. When Autostrassa fitted mine they said "Thats a really nice clutch ...what are you going to do to muck up the car more?" In fairness it wasn't as bad when it wore in. Initially it was like a switch.
My main disappointment was it wasn't as ziggy as I thought it would be. The lightened flywheel I had in Sluggy allowed it it rev like a motor bike engine. The 944 engine has so much inertia in the other components that the difference wasn't terribly noticeable. That being the case it isn't terribly detrimental either (once glazed in a bit) so my view is you might as well. While potentially a bit snatchy you are going to have access to more performance orientated specifications.
If I remember correctly I went for a SPECS single plate which might have been from Lindsey Racing (when exchange rates were much better).

Lightened Clutch John ? Are SPEC's clutch's lighter than OE? or do you mean the Flywheel..

Was "Sluggy" a turbo or N/A / and did it have a stock (heavy) crank but span up quickly only with a Flywheel change?
I was under the impression anything lightened in the engine does not produce any more power but speeds up the engine's
response time and hence from point A to B on a road gets there faster than a stock engine.. ?

R

 

[blade7]

I think the original pistons run a tiny clearance of around 0.001-2", the likes of Wossner around 0.004". You may only need a light cut/hone/polish on the block if that bent rod hasn't worn it's cylinder out of shape.

 

[John Sims]

Hi Graham,
Has been so long . With regard to the lightened clutch I was a little disappointed. When Autostrassa fitted mine they said "Thats a really nice clutch ...what are you going to do to muck up the car more?" In fairness it wasn't as bad when it wore in. Initially it was like a switch.
My main disappointment was it wasn't as ziggy as I thought it would be. The lightened flywheel I had in Sluggy allowed it it rev like a motor bike engine. The 944 engine has so much inertia in the other components that the difference wasn't terribly noticeable. That being the case it isn't terribly detrimental either (once glazed in a bit) so my view is you might as well. While potentially a bit snatchy you are going to have access to more performance orientated specifications.
If I remember correctly I went for a SPECS single plate which might have been from Lindsey Racing (when exchange rates were much better).

Lightened Clutch John ? Are SPEC's clutched lighter than OE? or do you mean the Flywheel..

Was "Sluggy" a turbo or N/A / and did it have a stock (heavy) crank but span up quickly only with a Flywheel change?
I was under the impression anything lightened in the engine does not produce any more power but speeds up the engine's
response time and hence from point A to B on a road gets there faster than a stock engine.. ?

R

It was a complete matched assembly including a clutch and flywheel. Subject to the format of a clutch it can be a great deal lighter than OE

Sluggy was a Westfield racing car with an ex works Formula Ford engine (originally).

Lightening the engines moving components potentially allows the engine to rev more freely as it has less mass to change velocity. However, it doesn't have the same reserve of stored up kinetic energy as a heavy engine so this also makes it easier for the engine to be slowed by external forces, hills, drag, etc. . As such it is much more reliant on good combustion (and the power created there by) to keep it running . An engine with lighter components might accelerate faster but may also struggle to achieve or maintain a high speed.

Quicker from A to B is dependent on where A and B are and the route between the two.

 

[924Srr27l]

Hi Graham,
Has been so long . With regard to the lightened clutch I was a little disappointed. When Autostrassa fitted mine they said "Thats a really nice clutch ...what are you going to do to muck up the car more?" In fairness it wasn't as bad when it wore in. Initially it was like a switch.
My main disappointment was it wasn't as ziggy as I thought it would be. The lightened flywheel I had in Sluggy allowed it it rev like a motor bike engine. The 944 engine has so much inertia in the other components that the difference wasn't terribly noticeable. That being the case it isn't terribly detrimental either (once glazed in a bit) so my view is you might as well. While potentially a bit snatchy you are going to have access to more performance orientated specifications.
If I remember correctly I went for a SPECS single plate which might have been from Lindsey Racing (when exchange rates were much better).

Lightened Clutch John ? Are SPEC's clutched lighter than OE? or do you mean the Flywheel..
Was "Sluggy" a turbo or N/A / and did it have a stock (heavy) crank but span up quickly only with a Flywheel change?
I was under the impression anything lightened in the engine does not produce any more power but speeds up the engine's
response time and hence from point A to B on a road gets there faster than a stock engine.. ?
R

It was a complete matched assembly including a clutch and flywheel. Subject to the format of a clutch it can be a great deal lighter than OE
Sluggy was a Westfield racing car with an ex works Formula Ford engine (originally).
Lightening the engines moving components potentially allows the engine to rev more freely as it has less mass to change velocity. However, it doesn't have the same reserve of stored up kinetic energy as a heavy engine so this also makes it easier for the engine to be slowed by external forces, hills, drag, etc. . As such it is much more reliant on good combustion (and the power created there by) to keep it running . An engine with lighter components might accelerate faster but may also struggle to achieve or maintain a high speed.
Quicker from A to B is dependent on where A and B are and the route between the two.

Ok I thought for a Second I'd missed out on getting Lighter Clutch cover , but you mean the Flywheel and Clutch cover were balanced (Matched)?
Oh sluggy wasn't a Porsche then but a smaller engine that revved like a Bike (Twin cam?)

How does an engine with lighter moving components struggle to maintain a high speed , only when it's going uphill or?

My engine has almost 10kg less weight than OE (Crank / Flywheel / "Half" Balance shafts / 968 Rods & forged Pistons) it does require more throttle
going up hills, but the acceleration from a standstill and speed is well worth the Hill disadvantage. It also decelerates much quicker when
lifting off the throttle, good for changing gear faster and also uses less brake pad material!

If a stock car v Lighter Flywheel / crank etc car was tested back to back 0 - 60, 0 - 100mph etc..From point A to B ( on the flat) the modified engined
car would reach Point B quicker than the stock one.

R

 

[John Sims]

...If a stock car v Lighter Flywheel / crank etc car was tested back to back 0 - 60, 0 - 100mph etc..From point A to B ( on the flat) the modified engined
car would reach Point B quicker than the stock one.

Perhaps, but there are a great many other factors which may well influence the outcome. Flywheels perform a function which is why motor manufacturers include them.

I wasn't aware you could do 0-100 in the UK without going to a track or outside of a competition event.

 

[924Srr27l]

...If a stock car v Lighter Flywheel / crank etc car was tested back to back 0 - 60, 0 - 100mph etc..From point A to B ( on the flat) the modified engined
car would reach Point B quicker than the stock one.

Perhaps, but there are a great many other factors which may well influence the outcome. Flywheels perform a function which is why motor manufacturers include them.
I wasn't aware you could do 0-100 in the UK without going to a track or outside of a competition event.

There's no Perhaps about it John, it's factual engineering.
Like for like the same car fitted with an OE Crank and then changed to a knife edged crank & Aluminium Flywheel
tested on the Flat @ Bruntingthorpe (the same car) will produce more power, spin up quicker and be faster from one point
to the next.

R

 

[John Sims]

Well unfortunately Roger I don't know everything about everything and can only call on first hand experience which I am no longer willing to relate so as to provide you with a spring board to demonstrate how clever you think you are.

 

[blade7]

Second guessing the Porsche engineers harmonic calculations is something not best done in a shed. Get it wrong and the oil pick up strainer could fall off and/or the bottom end fasteners loosen off...

 

[924Srr27l]

Well unfortunately Roger I don't know everything about everything and can only call on first hand experience which I am no longer willing to relate so as to provide you with a spring board to demonstrate how clever you think you are.

Chill John, it's ok
Discussions should be just that! there's no springboards or any need for personal insults again!

This Post is relative discussing lightweight components Flywheels etc.. But I'll start a new thread, that'll be best!

R

 

[924Srr27l]

Second guessing the Porsche engineers harmonic calculations is something not best done in a shed. Get it wrong and the oil pick up strainer could fall off and/or the bottom end fasteners loosen off...

Yes that's why I've not used anyone in a shed who second guesses.

Lindsey Racing Balanced the Crank, Rods and Pistons in the USA, Then the Crank was also Re-balanced
with the SPEC clutch & Flywheel at a UK Engineer's.

R

 

[blade7]

.

 

[GPF]

Hi Guys,

Minor update.

I decided I didn't fancy steel liners or nicasil coating so persevered with finding someone to hone/polish the alusil. That took a while - should probably have bitten the lead time bullet with Serdi in the first place!

The block's all done now though - ended up with first oversize, tolerance group 0 which means 100.50mm +/- 0.005 apparently.

The crank was ok but has been polished and balanced, and the original flywheel was skimmed and balanced too. Couldn't get windage ports done though

Need to source pistons now and probably go to forged rods, but still waiting for some ARP head studs to arrive and be fitted before I can collect everything and get it all back to the OPC.

I think Porsche pistons will be expensive so may go with forged Wossner, but I'm still waiting for prices. Any thoughts?

At least it's gone from "why the ....... did we start this" to having a nice fresh block ready to start putting back together!!