[Mk2] [Turbo] engine mods-worth it???

[lewis88]

hi, im rebuilding a rev1 tubby and im in two minds wether to just check the engine over and do "what needs doing" or to go all out and do this:

1 new race conrod bearings
2 new race bottom end bearings
3 full gasket kit
4 cometic headgasket
5 new timing belt
6 lightened and ballanced crank and clutch (can get this done relatively cheap)
7 port and pollish (by me)
8 check over the oil pump and waterpump etc
9 new piston rings
10 thermostat

the list just goes on and on when i start looking and see more worthwhile things to do!! so does anyone have any of these mods and can you give your oppinion on them please. ps im thinking about putting a big turbo on it next year

[Yas]

If you're going as far as pulling the engine apart... do it once do it right!

Stick some forged pistons in there rather than just new rings
New timing belt tensioner
New oil/water pump
All bearings main/big end/thrust
ARP bolts
Standard conrods are meant to be good for high hp but if you have the cash you can upgrade to steel rods

It's never ending really, depends what your aiming for powerwise as to how far you want to go on mods.

Have you got experience with port&polish?

Oh also... if it ain't broke don't fix it! But if you're going for a bigger turbo in the future I guess theres no harm in future-proofing the engine if funds allow.

[lewis88]

ive got a bit of expierience of porting and polishing (done a few bikes and had good results) ive got two heads sitting here both good. forgot to mention i was going to use arp headbolts and its just had a new timing belt with the tensioner, but im going to use a new belt for piece of mind.
not looking for massive power but my aims are to be around 320-350 after new ecu and turbo. oh ive also forgot ive got an st205 chargecooler setup to go on.

[Yas]

Right your not looking at massive power levels, i'd keep it simple tbh. Set of pistons, arp head and rod bolts, cometic hg, overhaul the rest as you said full gasket kit etc...

[Mike N]

If your going forged, get a rebore and go 86.25 min with 35/40 degr cross hatch honing.

Fitting 86mm pistons alone wont work that well unless the block is new or re-sleeved, Just honing old bores will give some amount of piston slap or too much clearance.

Machine the face of the block while your at it.

I have just bought a complete forged engine and the one it replaces is perfect less two cracked std pistons, the std bores look and feel great except there is a small ridge at the bottom of each cylinder, if a new forged piston was fitted and the bottom ring height was lower than an OE piston, this ridge may well break or damage an oil scrapper ring, so it will get a rebore - the results are 10 times better anyway and you know all is new.

The rest you mentioned is just right.

Mike.