Yet another Turbo engine build thread!

[PhilKent]

Hi Folks,
I built myself a 2.5L 16V turbo engine over the last couple of years and really enjoyed the project. It had full sequential injection and CoP.
I was enjoying driving it too until recently! No.1 con-rod decided to let go at about 6k revs in4th gear at Goodwood. It was messy...
But perhaps surprisingly the head has survived.
So, I'm on the hunt for a 2.5L block and perhaps any bits that folks may have from a project build that never got finished.
But also, I have a whole bunch of bits to offer any builders or tuners out there to help fund the project. These include (but not limited to);
8v Turbo cylinder head - complete and ready to fit.
8v Turbo cylinder head - Valves removed and hear-line crack across water gallery - project for someone?
8v N/A head - Modified with Turbo Valves, uprated valve springs, lightly ported.
2x Turbo Camshafts
8v camshaft housings powder coated black complete with Newmans Camshaft & cam followers (perfect for the 8V N/A head above)
8v camshaft housing powder coated black
Turbo Clutch & flywheel complete
Turbo x-over pipe - late model
Turbo x-over pipe - early model (fixed wastegate mount) modified to fit LR DPW or Tial WG
LR 'sport' Turbo (Somewhere between #48 & #53 super series today) modified by TurboDynamics with ceramic Ball Race Bearings.
Turbo intake manifold, powder coated black complete with throttle body (modified to delete cycling valve) serviced and sealed to ensure no vacuum/boost leaks

 

[blade7]

Time to go for more capacity then, might let my new set of Wossner 104mm 16v turbo pistons go for the right offer...

 

[scam75]

Ouch and good luck with the build. I think I've got a water pump gasket and couple of o-rings left from my build..............so not a great deal of use!

 

[dlknight]

Ouch - sorry to hear about this Phil, which rods were you using in your build?

I've got the Bridgeway 4340 connecting rods in my build, after a tip-off from David, I got mine on offer, but you might be able to get a good deal shopping around. Looks like they are just under £500 currently on part box.

 

[PhilKent]

I have a water pump going spare as well, just didn't put it in the list!
I have an aversion to Wossner pistons since DC's experience but going for a short stroke crank with bigger pistons is a tempting prospect..
I ran standard turbo rods and pistons (machined for 16v head). This may well have contributed to my undoing...tips on suppliers for parts very welcomed thanks....never heard of Part Box before...

 

[PSH]

Sorry to hear of your woes Phil, I'm sure you'll be back on the road again soon. Out of interest, which rod failed...no2..?

Pete

 

[blade7]

I have a water pump going spare as well, just didn't put it in the list!
I have an aversion to Wossner pistons since DC's experience but going for a short stroke crank with bigger pistons is a tempting prospect..
I ran standard turbo rods and pistons (machined for 16v head). This may well have contributed to my undoing...tips on suppliers for parts very welcomed thanks....never heard of Part Box before...

Wossner issues were when running in Alusil cylinders. DC is running liners now, and wossners are fine in liners.

 

[PhilKent]

It was No1 Pete... It was a lovely engine until it went bang!

 

[PSH]

It was No1 Pete... It was a lovely engine until it went bang!

Rod itself fail or the wrist pin bearing? Those bearings...well just a brass sleeve really, take a hell of a beating, oiling is critical which is why they usually fail on No.2 which has a known design flaw in its oiling. When rebuilding mine the sleeves where oval shaped, a fact I hadn't first noticed until beginning to rebuild. I can't recall now if I got Serdi to just replace like for like or if I asked for bronze bushes? The Olde Memory hasn't got any better over the years...

Pete

 

[scam75]

I got messed about by Wossner who first sent me 16v pistons for my 8v then couldn't supply me a set of uncoated 8v ones. I went down the iron liner route and got a set of bespoke forged JE pistons. I sent a place in Cambridge one of my original pistons and they made up a set for me. About £700 and they've done 15k miles happily so far.

 

[blade7]

I got messed about by Wossner who first sent me 16v pistons for my 8v then couldn't supply me a set of uncoated 8v ones. I went down the iron liner route and got a set of bespoke forged JE pistons. I sent a place in Cambridge one of my original pistons and they made up a set for me. About £700 and they've done 15k miles happily so far.

I bought the Wossners I have from Baz Hart of Hart Racing. The only reason I'd part with them is because I'm not sure if the 16 valve crowns would require slight machining to work with my 2.7 cylinder head. Not an issue for me to keep them, just in case I ever needed them. Or if I found a complete S2/968 head for the right money.

 

[dlknight]

I use Mahle Motorsport PowerPak pistons in my rebuild and kept the alusil bores which were enlarged to the first repair diameter (8v) so 100.5mm. Mahle Motorsport (in the USA), were very good in answering my queries and putting my mind at rest with some gossip floating around on forums.

They do supply 968 Turbo 3.0L pistons for factory aluminium bores, with similar compression to the 2.5 Turbo.

Have a look in the catalogue on page 5.

Porsche Pistons & Cylinders - MAHLE North America

www.us.mahle.com

 

[dlknight]

https://www.design911.co.uk/p/engine-piston-set-porsche-968-3-0l-for-use-in-factory-aluminum-bores-only/

BTW if you are looking for someone to machine the replacement bottom end then I can thoroughly recommend David Knight (no not me) at Knight Engine services in Northants, he knows all about Alusil and has lots of experience with Porsche. They also have the proper machines specified in the workshop manual and Kolbenschmidt Alusil documentation.

 

[PhilKent]

Thanks for the tips guys. TBH I didn't think there was anyone left doing Alusil. Last build I got Capricorn Automotive to do the block with Nickel Ceramic. It was a bit of a faff as they initially bored my 2.5 out to 104mm as most of their work is on 3ltr blocks, but we got it sorted with new inserts back down to 100mm. They did a very nice job in the end... I may use them again, (if they respond to my email!) but also wondering about iron liners or maybe the Alusil...if I find a decent donor block.
Finding a good machine shop is one of the hardest part so thanks for the tip David...
Pete - My rod went as a result of the big end failing via a snapped stud I think. Can't be sure tbh... But the piston crown and pin end are okay. Side wall of the piston took a hit from the con-rod at some point. Piston crown has slight chamfered edge where it kissed the head with some force. Valve train and belt okay and only two slightly bent valves....My valve reliefs machined into the crowns were not full clearance, but helped I think...

 

[blade7]

I use Mahle Motorsport PowerPak pistons in my rebuild and kept the alusil bores which were enlarged to the first repair diameter (8v) so 100.5mm. Mahle Motorsport (in the USA), were very good in answering my queries and putting my mind at rest with some gossip floating around on forums.

They do supply 968 Turbo 3.0L pistons for factory aluminium bores, with similar compression to the 2.5 Turbo.

Have a look in the catalogue on page 5.

Porsche Pistons & Cylinders - MAHLE North America

www.us.mahle.com

Years ago when I was very motivated to build a 3.0 turbo engine, I wanted to keep the Alusil bores in my 2.7 block. I remember reading about those new Mahle 968 turbo Powerpak pistons, and as I used to visit California every summer, I was going to pick up a set and save the postage and import duty. Then I read of a couple of confirmed cases of issues with the then new Ferroprint coating failing. Maybe Mahle have sorted out the coating now, but If I ever build an engine it will have ferrous dry liners, maybe plated and installed by Capricorn.

 

[dlknight]

Years ago when I was very motivated to build a 3.0 turbo engine, I wanted to keep the Alusil bores in my 2.7 block. I remember reading about those new Mahle 968 turbo Powerpak pistons, and as I used to visit California every summer, I was going to pick up a set and save the postage and import duty. Then I read of a couple of confirmed cases of issues with the then new Ferroprint coating failing. Maybe Mahle have sorted out the coating now, but If I ever build an engine it will have ferrous dry liners, maybe plated and installed by Capricorn.

There are a couple of uncorroborated reports of engine failures with Mahle pistons on rennlist, I've seen them Paul, the thing is they get repeated ad infinite until everyone believes them. Barring the obvious recent issues with Wossner pistons, I will obviously eat my words should anything happen to my build, but I can't see how a big name like Mahle would continue selling pistons if there was such an obvious flaw in their construction. This is something I asked the engineer about at Mahle Motorsport and he came back with the response below. The thing is nobody knows who assembled these engines or who performed the machine work and with what equipment. I've read threads on rennlist where people claim to have honed their alusil blocks with nothing more than a power drill and polishing pads, you can draw your own conclusions on some of the failures. There is also a difference between Mahle and Mahle Motorsport (USA), Mahle are standard pistons from Germany, with the Motorsport pistons from the USA.

"Yes, the skirts are coated with Ferroprint. You do not want similar materials against one another creating friction due to galling. So the Ferroprint has iron content to where the aluminum/iron footprint on the skirts."

EDIT: There was an interesting thing I found when assembling my engine as I'd assumed the arrow on the pistons pointed towards the front of the engine, but after confirming with Mahle Motorsport the arrow points towards the flywheel. This is because the pistons are offset. Other manufacturers sometimes have the arrow the other way around so it is something that should be checked before assembly.



The gold standard is obviously Nikasil, but it is a very expensive process which is why people go down the liner (or Alusil) route. I had the option of the Nikasil but it was more than double what I paid for the Alusil.

BTW I was told Capricorn will no longer deal with individuals (unless you want to wait a very very long time), they have tons of work from motorsport and tuning businesses. It was EMC that offered to include my block with a batch of theirs the next time they visited Capricorn, you may be able to get it done via this route.

This isn't just a Porsche thing, several BMW engines (and I believe Mercedes) also are made with Alusil, and there are well regarded tuning shops tuning these engines and keeping the Alusil.

Partee racing in the USA and their engine workshop where they work with Alusil -

 

[PhilKent]

I did have to exercise a lot of patience with Capricorn last time and they are so far remaining silent to my enquiry... :-( I searched for EMC as I had dialogue with them on my last build, but they seem to have stopped trading?

 

[dlknight]

I did have to exercise a lot of patience with Capricorn last time and they are so far remaining silent to my enquiry... :-( I searched for EMC as I had dialogue with them on my last build, but they seem to have stopped trading?

EMC still trading, they have moved to Ledbury.

EMC Motorsport | Ledbury

EMC Motorsport, Ledbury. 544 likes · 1 talking about this. A company specialising in the preparation of competition vehicles.

www.facebook.com

Though Kevin can be an interesting character

 

[blade7]

I don't really have any dog in this fight. But when I started looking for the best 944 turbo I could buy nearly 20 years ago, I also had a plan to build a up a 3.0 engine. I'm not sure when it happened but Mahle had to stop using the Ferrostan coating for environmental reasons, and started using something called Ferroprint. I do remember pictures of Ferroprint pistons where the coating hadn't galled, it had come off in lumps. Anyway engine builders started using Wossner pistons, which worked fine, until recently. I'm not sure you can compare chemically etched modern Alusil engines with 30-40 year old blocks refinished with pads and paste either. It would also be interesting to know how many respected US 944/68 engine builders are using Alusil these days.

 

[dlknight]

I'm sorry Paul, but you post the same stuff on multiple forums which you've heard third hand, if you had specifically experienced an issue and presented the evidence then I'd be inclined to believe it. You are referring to one specific post which I've seen myself on Rennlist and there was no concrete conclusion of what caused the issue. Nobody knew who the machine shop was and who specced the clearances etc etc.
If you care to watch the video above, they discuss all the things that you have mentioned and also cover partly why Alusil has a bad name amongst rebuilders. There is also a manual from Kolbenschimdt the manufacturer of the Alusil blocks on reconditioning which echoes what is in the Porsche 944 workshop manual. Sreten rebuilt another BMW alusil engine last year and used the same type of Mahle Motorsport pistons with the Ferroprint coating and has had no issues (I think I posted the link somewhere in my rebuild thread).

There are many reasons people go down the liners route, and the most common one is cost as it is cheaper than alusil or nikasil and more straightforward for engineers used to iron blocks.

Sorry to hijack your thread Phil.