3 litre 8v dilemma

[JamesO]

I currently have a bit of a dilemma. The 968 engine in my lux was cheap because the exhaust cam is missing one tooth so I have been running a s2 head and cams. Annoyingly I discovered when changing a sticky tappet that the cam saddles and both cams have become scored very badly (they were definitely fitted in the correct order and way round).
I have removed the head and taken it to the machine shop to see if it can be saved, in the meantime I have decided to fit the 2.7 head off the old engine while I decide what to do.

As I see it my options are as follows:-

1. New 968 cam, very expensive and should be done in pairs.

2. Have the 968 cams repaired by RS Barn $650 plus shipping twice, import duty? and a long wait.

3. Stick with the s2 head depending on the report from the machine shop.

And the slightly daft option but most interesting

4. Take advantage of the lower compression ratio with the 8 valve head and go for a lowish boost turbo.
Lurking in my garage I have a turbo inlet, throttle body, intercooler and intercooler pipes so would still need a fair few bits.

Any opinions?

 

[333pg333]

Too tired to think clearly at the moment...but there has been a couple of people I know of that have turbo'd either a single or twin cam head motor with stock internals at lower boost range. You could even use a thicker headgasket. So you have 16v pistons in there now? I think this should be ok to use with the 8v head. Obviously you'd need some kind of controller unit like a Vitesse or similar piggy back. You could go a cheaper standalone. There's a new LINK Atom that has been released which has been aimed at a lower budget build. Maybe even an Apexi unit? Then there would be some other ancillaries...but you wouldn't be spending that much more than the other options you have nominated. Definitely food for thought. If you want to search on Rennlist look at usernames 'Markus951' and 'Mikes3.0cabturbo' . These are 2 guys I know of, and have actually met by coincidence, that have turbo'd with stock internals. There should be plenty to read about to make an informed decision.

 

[nick_968]

James

Just a word of warning, there is no such thing as a cheap turbo conversion and most end in tears, both those mentioned above suffered terminal engine damage at some point. You may be able to avoid the same problems they had if you run really low boost and dont run it hard, but with the 8v head, reduced compression and low boost you wont be a million miles away from the hp of a well tuned 16v 968 engine, albeit without the turbo torque curve. If you go to standalone add on plenty of money for dyno time, wiring, sensors etc and be prepared to go more than once before you get a good setup. There will be lots of other unforseen problems along the way so budget for that too. In the end it would be way cheaper to just sell your car with its original engine and buy a 944 turbo! Lots of people have tried to do a cheap 3.0 turbo but so far the closest to succeed was Marcus951 of rennlist mentioned above, he made his own manifolds and was generally very resourceful and handy with the tools. He had a great setup but even that didnt last although it was destroyed by an overboost situation from memory most peoples experience is that the standard internals will not be up to the job long term. If I were you I would bite the bullet and get the 968 cams done. I still have the engine from my 968 from before I installed the 3.0 turbo engine but that would be an even more expensive option for you as its low miles and you already have the bottom half.

 

[edh]

ORIGINAL: nick_968

James

Just a word of warning, there is no such thing as a cheap turbo conversion....

Absolutely spot on - I'm sure your cheapest & best options are another S2 head (assuming chains, cam/sprockets etc are brought up to scratch) or 968 cams. I wouldn't have thought Nick's complete 968 engine was too far out of that ballpark either as it would release some bits to sell - like the 2.7 head and the 3.0 bottom end.

 

[JamesO]

Thanks for the input guys, The turbo idea was after a few shots of JD to cheer myself up.
I have dropped the 968 head off to the machine shop for check over and skim as I think the s2 head is shot.
Going to contact RS Barn and get the cams sorted. Until then I'm going to run the car on the 8 valve head until I get the cams back, very glad I have a mappable ECU.

 

[Diver944]

I was about to agree with the boys until I saw and remembered that you already have a mappable ECU with the Microsquirt. The standard 3 litre rods and pistons are not up to much boost at all but if I remember back to when my own 3.2 engine was being run in on less than 6psi it still made a very rapid and useable engine compared to a tweaked 2.5 Turbo.

I don't think you are shooting for big numbers but just looking for a way out of your problems. I think a 3L 8v turbo with very low boost would still give you circa 280bhp but wih a heck of a lot more torque

 

[JamesO]

O.k, looks like the head studs are shorter on the 8 valve engine, I've taken about half out by using the double nut method but the rest are pretty tight. Any tips to get them out without damage? I tried a bit of heat to break down the loctite but don't want to go too mad with the heat.

Hmmm 280 horses tempting.. Must be sensible and avoid looking for written off/rusty turbos

 

[nick_968]

You need to get a lot of heat on them to break down the locktite if they are not coming easily, heating the block to 250 degrees. Make sure the double nuts are extra tight against each other like 100nm. Get a big spanner on there on the bottom nut or both if possible. If you dont melt the locktite you will snap the studs.

 

[JamesO]

Cheers might have to invest in one of those laser thermometer things.
Have mailed RS Barn to get an idea of timescales so my patience verses chances of snapping a stud for what will be a temporary repair will have to be balanced.

 

[barks944]

Got a K26/6 here, its leaking a bit of oil and needs a rebuild but its in good nick otherwise . Also have a turbo exhaust system inc downpipe if you are interested....While were at it I also have a crossover and wastegate too!

 

[JamesO]

mmm Turbo must resist.

 

[barks944]

Come over to the dark side!!

 

[robwright]

ORIGINAL: barks944

Got a K26/6 here, its leaking a bit of oil and needs a rebuild but its in good nick otherwise . Also have a turbo exhaust system inc downpipe if you are interested....While were at it I also have a crossover and wastegate too!

I have a K26/6 in good condition apart from the compressor wheel. Free to a good home if you want. Sounds like a good project would be happy to help you with it.

 

[nick_968]

If anyone has a K26/8 in need of repair I would like one to play around with.

 

[333pg333]

While I agree with Nick in principle (and practice), I think it's still do-able on a less than 'Kabillionaire' budget. Both Mike's and Markus' builds went very well until both motors suffered due to increase boost. Markus had actually sold his motor by then so it wasn't actually he who had the accident. Mike couldn't resist turning up the wick. Now it's possible that both of these motors may have been weakened over time with forced induction but I can't be sure. Markus reached somewhere near 500bhp on his so lets assume this is possible! You could also buy some custom Wossner pistons for approx. 700GBP. Rods are not too expensive either from the same maker if my memory serves me correctly....it does beg the question....

 

[barks944]

ORIGINAL: 333pg333

While I agree with Nick in principle (and practice), I think it's still do-able on a less than 'Kabillionaire' budget. Both Mike's and Markus' builds went very well until both motors suffered due to increase boost. Markus had actually sold his motor by then so it wasn't actually he who had the accident. Mike couldn't resist turning up the wick. Now it's possible that both of these motors may have been weakened over time with forced induction but I can't be sure. Markus reached somewhere near 500bhp on his so lets assume this is possible! You could also buy some custom Wossner pistons for approx. 700GBP. Rods are not too expensive either from the same maker if my memory serves me correctly....it does beg the question....

What were the details of those builds?

 

[nick_968]

ORIGINAL: 333pg333

While I agree with Nick in principle (and practice), I think it's still do-able on a less than 'Kabillionaire' budget. Both Mike's and Markus' builds went very well until both motors suffered due to increase boost. Markus had actually sold his motor by then so it wasn't actually he who had the accident. Mike couldn't resist turning up the wick. Now it's possible that both of these motors may have been weakened over time with forced induction but I can't be sure. Markus reached somewhere near 500bhp on his so lets assume this is possible! You could also buy some custom Wossner pistons for approx. 700GBP. Rods are not too expensive either from the same maker if my memory serves me correctly....it does beg the question....

Questions for you Pat.....

1. On average how much more in % do you spend on a project than you originally budgeted?
2. How easy is it NOT to turn up the boost?
3. Add the rods, the pistons and your into the same territory as any other 3.0 build and you know where that ends right?

[8D]

 

[sulzeruk]

I have a good usuable S2 head here if needed. Complete with valve.
Alasdair

 

[JamesO]

Cheers guys and thanks Rob for the kind offer of the free turbo.
Had to work late tonight so not looked at the car. Will have to work out exactly what parts I would need for the low boost turbo option, what can be used and what really needs to be new. Not that i'm thinking about anything as silly as that honest...
New 968 cams or used s2 head with cams seem like the most sensible option.
The tinkering is half of the fun for me but I don't want to miss the summer.
If the cars not too dog slow with the 8v head it gives me time to collect parts/think, whichever way it goes.

I used to be undecided now i'm just not sure.

 

[333pg333]

ORIGINAL: barks944

ORIGINAL: 333pg333

While I agree with Nick in principle (and practice), I think it's still do-able on a less than 'Kabillionaire' budget. Both Mike's and Markus' builds went very well until both motors suffered due to increase boost. Markus had actually sold his motor by then so it wasn't actually he who had the accident. Mike couldn't resist turning up the wick. Now it's possible that both of these motors may have been weakened over time with forced induction but I can't be sure. Markus reached somewhere near 500bhp on his so lets assume this is possible! You could also buy some custom Wossner pistons for approx. 700GBP. Rods are not too expensive either from the same maker if my memory serves me correctly....it does beg the question....

What were the details of those builds?

Pretty easy to look up on Rennlist Tom. Just check under the usernames posted above. Duke wound up buying Markus' motor and it was he who ran into the issues with it. He now has a 3L 16v build that is also viewable on Rennlist at the moment.