Turbo options

[Weiß-sechs]

We're finally making some progress with the oil cooler repair/turbo upgrade

The engine's been out for almost 5 weeks now waiting for the hybrids and shiz (the Christmas break completely messed up my optimistic plans of having her back OTR by early Jan); work has been done to replace the fuel tank non-return valves which were throwing up "evap" codes and the leaky rocker cover gaskets replaced. A general mooch around the mill has revealed head gaskets past their best; the garage recommends that they're replaced now while there's easy access, can't argue with that tbh; they've quoted £329 inclusive for both gaskets, a new cam belt (bit of a ball ache really as the one that's on has only done 3k, not going to skrimp on that area though) and the labour.

Fair price?

[Nobby]

£329 for headgaskets swap! That sounds massively cheap. The cambelt is atleast £40 and a new gasket set must be over £100 (might be a few other things included in that too). I don't know if you need new headbolts but they aren't exactly cheap.

How can they tell its past its best - oil seeping out the side of the gasket? If there is a problem you need to be 100% sure why that problem has happened in the first place. There is no point sticking on a shiny set of gaskets if the head(s) are bent and need a skim.

If I was you I'd be thinking about compression lowering gaskets too if that was the case.

[bam_bam]

Factor in head skim?

[Weiß-sechs]

The terminology used was "looking a bit crusty". The engine has covered over 120k with no record of ever having head gaskets changed plus the hybrid turbos are going to add quite a lot of extra boost so it's probably a sensible move to replace them now while there's plenty of room to manoeuvre.

You're about right on your costings plus 3 hours labour

What benefit will I see from the lower comp gaskets do you reckon? Won't that increase turbo lag? Will a head skim have the same effect? Seems this isn't going to be as straight forward as I thought

[bam_bam]

The terminology used was "looking a bit crusty". The engine has covered over 120k with no record of ever having head gaskets changed plus the hybrid turbos are going to add quite a lot of extra boost so it's probably a sensible move to replace them now while there's plenty of room to manoeuvre.

You're about right on your costings plus 3 hours labour

What benefit will I see from the lower comp gaskets do you reckon? Won't that increase turbo lag? Will a head skim have the same effect? Seems this isn't going to be as straight forward as I thought

You're not going to be able to get much out of the hybrids without lowering compression. The increase in lag will be imperceivable, you're running a 4.2L, not a 1.0L. Again, without CLG and tubulars it'll be hard to increase boost and get it out of the engine, keeping in mind the that you'll also need to support flow in with custom intakes. Which brings us full circle, the limiting factor in all of this (assuming everything is supported and is copacetic), the RS6K04 hotside is the limiting factor on a 4.2L (not so much on the 2.7L or stroked 2.7->3.0L). Head skimming ain't that expensive but you should be ready for it since the heads are being lifted.

[Weiß-sechs]

Thanks for the advice, I'm going to pop down later this aft and have a chat

[Bladerider]

Not sure why you need GT30's

Big 2860's will see you to 650+ and 2871R's will see you pretty much to 750+ and if you get a GTX2867R (or similar billet wheeled HTA type) you should see the spool times getting almost back to standard i would have thought.

J.

[Weiß-sechs]

Not GT30's mate, you'll need a manual 'box conversion for those big snails.

Got hybrid K04's (as previously posted)

[bam_bam]

Not sure why you need GT30's

Big 2860's will see you to 650+ and 2871R's will see you pretty much to 750+ and if you get a GTX2867R (or similar billet wheeled HTA type) you should see the spool times getting almost back to standard i would have thought.

J.

Even the GT28s don't fit with a slushbox, better people than us have tried. I think Jordan was first to pull and give it a bash. I've checked the lengths before (k04 is 196mm vs 198mm GT2860) but there's more to a turbo frame than the length, square peg, round anus and all that.



vs



The other thing is the current 'box is at the torque limit.

Also, you'll need a custom manifold and customised DPs for the most part staying with K04s is a smarter choice.

However, I do agree about the GT2867s, it'd be a better option if manualizing a C5, it'd be far more usable and probably a better drive.

[Weiß-sechs]

Nipped round earlier to see how we're progressing.

Settled on standard head gaskets in the end; lower comp are an option but too much of a compromise as far as longevity is concerned, far better to use lower compression pistons if going down that route but can't really justify a full engine rebuild ATM......

Bores and head a looking good for an old 'un

[bam_bam]

Looks good, as if I know what I'm looking at...

[amanda1]

Nipped round earlier to see how we're progressing.

Settled on standard head gaskets in the end; lower comp are an option but too much of a compromise as far as longevity is concerned, far better to use lower compression pistons if going down that route but can't really justify a full engine rebuild ATM......

Bores and head a looking good for an old 'un

I would agree on lowering gaskets and cams to be fitted : plus anything else that looks iffy as well.

[Bladerider]

It didnt post the earlier quote about GT30's I was replying too,

I didn't have time to read everything and just replied to where I had gotten to in the thread, there's always a way to make stuff fit !!

Bores and head do indeed look good - love the clean spots from the inlet washing !!

Has anyone got far enough to think about squish removal or isn't that something thats been an issue yet or is 5v unfriendly ??

J.

[sweegie]

Head does indeed look in great condition. Are those fret marks around the fire rings, or just a bit of discolouration? Don't skim unless you have to

[Weiß-sechs]

Head does indeed look in great condition. Are those fret marks around the fire rings, or just a bit of discolouration? Don't skim unless you have to

No, not planning on skimming but haven't seen bank one yet, hopefully it'll be good.

I was more impressed with the condition of the Nikasil cylinder coating, really is flawless , I wonder why Porsche have so much trouble with the coatings in their blocks?