New_scooby_04

iTrader: (4)

Hey, I'm on commission!!!

Besides, one the hardest lessons in life is knowing which assess to kiss and which to kick.

Seriously, friendly banter aside, I can tell you that API are an excellent company and that David is a genuinely nice chap, who looks after his customers and happily offers advice even when he doesn't directly benefit.

Ns04

[Davey]

Im not denying that in the slightest!

But i'd be EVEN nicer to you if you paid ME £2000 to rebuild your engine

Dont worry.. I have nothing against anyone, I am just trying to explain that you dont need to spend £2000 on a rebuild, unless you are looking for some serious power.

pslewis

Actually, I would consider having sex with you for £2000

You do have Gold Wheels don't you??

Pete

New_scooby_04

iTrader: (4)

As long as you promise not to regrind the crank!!!

Seriously, that won't be required, though, don't tell Pete, but I use SN **** oil and SUL and I have a kn(c)ocklink!!

New_scooby_04

iTrader: (4)

Why Peter, I didn't know you cared!!

Ns04

pslewis

Sorry, the sex is now OFF the menu!!!!

Pete

Palmo

Going off the point of this thread a little now - I have already said I was wrong. Will be more cautious this time, but don't think they fitted the 1.2 pushrod to the nova - the majority were indeed OHC - but as I said, forgot about the 1.0 version.

The pushrod engine was indeed fitted to many earlier vauxhalls dating back to Viva and before of various capacities.

jaytc2003

iTrader: (1)

it was only in the earliest 1.2 novas, probably using old stock up before they went the ohc route, but like you say other vauxhalls had them as well

codek

sure spending 2k on a car only worth that doesnt make much sense, but 2.5k for a 2.5ltr conversion is an option no?

madmoog

iTrader: (1)

Yes and No, well sort of...

Spending £2k to get a good engine in a car only worth the same can be a very good investment, if it the rest is sound and it goes for another 50-100K. Or, would it be better to by a brand new car and suffer more depreciation in the first 6 months (or even as it leaves the forecourt!). Your decision, many buy new cars..... Case in point: old 205, sound apart from the engine, nice rebuilt Mi16, very fast little car. The engine cost more than the car, but short of spending a hell of a lot more an a very good hot hatch, a fine (and fun) investment!

Rebuild or 2.5? I went for the 2.5 (although a EZ30R sounds interesting but that's another thread...) rather than a rebuild, as the 2.5 was the longterm intention, rather the existing engine brought the plans forward rather unexpectedly If going for a 2.5 it's good to start with an STi (for the heads) and don't forget the cost of an ecu/remap. Running it in at the moment but very impressed so far

rant over

[Davey]

How do you work that out?? It only takes one moron to crash into the back of your car and you've lost it all, the insurance company arent going to pay out for your re-build, they might take the invoice into consideration but they wont give you the cars value + 2k..

APIDavid

iTrader: (4)

Subaru cranks - in keeping with many other Japanese models have very thin hardening to the bearing surfaces. Once ground you will have removed all the surface treatment and the crank will be soft.

You can of course re-harden the crank, but then it'll need straightening as the heat treatment process warps any crank. The straightening process can cause hairline fractures around the radius at the bearing surface edge. stress relieving can sometimes help but is by means an exact science. The cracks can and will fracture and then you have 2 cranks!!

All in all, the safest way is to replace the crank with a new one. Especially on any engine giving decent power. We have, in the past, reground cranks on Uk Imprezas that only make 210 - ish horsepower. This has been at the customers wish and against our advice. The crank for an Impreza are not expensive and given that it produces a known result - why not??

The crank is the first thing into a rebuild and the last thing out on strip. Thus, it is a major labour cost to get at it should the job go wrong. Unlike a 'normal' upright engine where the crank can be inspected or removed without removing a cylinder head.

If the engine needs to be warranted - and all ours no matter the power are -we need to be sure of the build quality. If you want to build your own engine with a reground crank that is your choice. We won't.

David APi Engines / APi Impreza
www.apiengines.com

[Davey]

The if they are being heat treated for hardening then the crank should be "hardened" almost all the way through?? What method are they using to harden just the crank surface?

APIDavid

iTrader: (4)

Most cranks have rudimentary heat treatment that is barely 5 thou deep.

If you hardened it right through [ actually impossible from my recall ] it would be way too brittle and would fracture at the first decent hammer blow of compression or boost or Det.

David APi

[Davey]

I see your point, but that does not mean you categorically can not re-grind the crank.. personally I'd have no qualms about a mild re-grind to remove any minor surface imperfections/scores..

APIDavid

iTrader: (4)

Like I said before - Good luck !

Jolly Green Monster

iTrader: (4)

There is also the issue of cleaning all the swarf from the failure and the grinding fully out of the crank.

APIDavid

iTrader: (4)

Which is a VERY important issue that I had forgotten in the hurry to explain why you don't grind cranks. Thanks for your input JGM, that's possibly even more important than the lack of surface hardening after the grind.

David APi

[Davey]

Should be no problem with Induction hardening (which is probably how they are hardened from new).. This gives a hard outer surface without deforming or making the rest of the structure brittle, And a chemical or ultrasonic clean will take care of the swarf after grinding

dynamix

iTrader: (3)

i reckon £2k for API is a bargain for a full build with warranty if it goes pop from people that know what they are doing. hopefully i will never have to pay it but who knows.

pslewis

I was case hardening cranks in the 1970's!!!!

WTF is all that about warping the crank?????

I very much doubt it .... crank is heated and case hardened - why the hell would it warp?? Unless the person doing the job is a clown??

Pete

360ste

iTrader: (1)

How? By talking to them??

justanotherperson

And if you were case hardening all those years ago you would know this,but for anyone else who wants to know, i will explain.

The process of hardening the surface of steel whilst leaving the interior unchanged. Both carbon and alloy steels are suitable for case-hardening providing their carbon content is low, usually up to a maximum of 0.2%.
Unlike carbon rich steels which can be hardened by heating, mild steels do not contain enough carbon to perform this operation. Instead carbon is forced into the skin of the metal to produce a piece of mild steel which has an outer casing containing more carbon than its core. This process is known as case hardening. The mild steel is heated to a bright red and whilst it is softer it is dipped into a carbon compound which soaks into the outer surface. One dipping is not enough and re-heating and dipping should be done several times. This will produce a carbon rich skin or case of about 1mm thick. Once the casing has been produced the metal is heated to a bright red and this time dipped in water to harden it.
Case hardening can be useful for making pieces which need to be hard on the outside to resist wear and tear, but softer on the inside to resist shock or sudden blows.

In bold is why the metal might *warp/move/bend*

By the way Pslewis did i mention that i have been an Areospace Engineer for 20 years now,before you start attacking what i say.

Hope this helps.

Tidgy

personally i use scoobyclinic for all my work, however i have got a mate who had an engine built by api and he was well impressed.
hope that helps

ZEN Performance

As both a competitor, customer and supplier to API, I have to put my hand up and agree with David.

£325 for a new crank, is by far the preferred solution when doing a rebuild. Okay so not very engine needs super duper this and that, but a burnt piston failure is a serious job.

If this were a failing bearing, that hasn't scored the crank, then you could maybe get the rebuild done for £1100 on a tight budget (crank, shells, head gaskets, sundries). As soon as you start depositing serious amounts of metal in the oil, it's game over for many more components, and thelabour required to strip, clean and check everything goes up.

In the case of a piston being holed, it will deposit much of that missing piston into the oil. ALL the bearings of the crank will likely be scored, the oil pmp rotor may be scored, the cylinder wall may be eroded (if the piston burnt through the rings) and everything throughout the engine will be contaminated.

Before you finish you will definitely need the following.

Head gaskets
Block o-rings
Modine oil cooler
Crank
Bearings
Pistons
Rings
Rebore and hone
20 hours of labour (minimum)

You will probably need an oil pump, possibly block and heads to be refaced (in case of det damage that caused piston failure), and perhaps further labour, valve seats to be recut, valves to be refaced (aluminium deposits cling to valve seat which can lead to seat erosion).

Regrinding used subaru cranks is a no no. Personally I am not aware that they are case hardened, and certainly some seem tough throughout the section. However a used crank will have lots of oil residue trapped behind the plugs for the cross drillings, this residue (sludge basically) will be enough to trap swarf/filings from the regrind process. If some does get trapped, it may or may not decide to make its way back through the engine at some point, potentially killing the bearings as it does.

The most important thing is to get to the route of the problem or it will happen again for sure.

Paul

Tidgy

well said that man!!!

you can say it may be this, maybe that all day long but you'll only find out when engine gets cracked open and damaged level acertained

STI Craig

asssssssssssssssssss

i just rebuilt my engine my self and had the crank reground.

i have just run it in and in the next day or so im going book it in with with andy F to get it mapped

sould i be worried about it failing again as i will be expecting 350bhp.
im pooing myself now!!!! just cant aford to rebuild it again!!

also i have replace the maf, oil pump etc

justanotherperson

i would say the risk will increase with the amount of metal that has been removed.
Any crank grinder who knows his stuff, Should have notice the difference between hardened and soft metal.
The wheel would stay nice and "open" whilst grinding the hardened stuff (realatively) but as you go through the hard and in to the soft, his wheel would "load" up and could quite easily clog up,which would also give a finish difference,combined possibly with a noise difference,as grinding hardened and soft metal will have a different sound,going from one to another in a short space of time will be noticeable.

Do you know what the oversize bearings were compared to the standard size ones are,this will give you a clue on the amount of metal removed.

If what Zen says is true about the cranks not being case hardened (and i have no reason what so ever to believe different) then it might not be "too" much to worry about,that said, im an engineer not a Subaru engine builder.

STI Craig

i think they wer 0.5mm oversize,
i used a company call headshop uk
they do alot of old austin martins, jags etc

they seem to know there stuff,
i think the best thing to do will be to just cross my fingers and hope for the best.

ZEN Performance

For many cranks removing swarf isn't an issue as they either have plain oilways or removable core plugs on the cross drilling. The subaru factory cranks have a ball bearing peened in place, so the only way to run a brush right through the oilway is to remove it, and it can only be removed by spark eroding it out.

Perhaps a minor risk, but compared to the low price (given the high quality) of a new crank I think it's worth replacing it.

Paul