306oc - Peugeot 306 Owners Club & Forum

Regarding head bolts, head gasket and skimming pistons...

The plan is to keep to under 30psi with my 'bigger' turbo. But even so i am wanting to take precautions to keep some sort of reliability (don't laugh ) at around 200bhp by lopping off some compression and using hdi rods.

Which gasket should i use with the skimmed pistons? - The thickest gasket available?

I remember reading about some uprated cheaper stud/nut combo head fastners (think Ruan may have mentioned it) as an alternative to ARP stuff. Is anyone able to shed some light on that please? While the engine is apart, i might as well splash out now and sort things to stop the head lifting/gasket going again in future.

Finally, any advice on the amount of material to skim off the pistons - 5mm? Or atleast a target compression ratio that i can work towards would be kl.

i'd also be interested in this. are the hdi rods much stronger than stock? has anyone managed to kill em? i know darren used some for a while but cant remember if they went or not.

d-jimbo Wrote:i'd also be interested in this. are the hdi rods much stronger than stock? has anyone managed to kill em? i know darren used some for a while but cant remember if they went or not.

Well Darren now has forged rods........go figure!

the HDi rods are a good bit beefier around the small end than the stock DT ones are

HDi rod = left, DT = Right

Fyi darrens forged rods are 1mm shoter than standard I believe and he needed the supercharger for it to rum.

Do NOT take 5mm off the pistons lol! It won't start for certain.

You're talking in the reigon of 0.5mm-1mm... And that'll reduce it quite a lot...

i actually meant 0.5mm 5mm?!

(i'm part way through an all nighter in an attempt to reset my buggered sleep pattern, shoot me now! :cry: )

Mark, the small end on the right rod actually looks thicker than the left? :? Should i be worried about my health or did you mean the right rod is from a hdi?

On a side note, after having a blat in my mates cooper s yesterday, i am addicted to that supercharger wine and instant pull! A supercharger + the Ve fueling range is surely a match made in heaven!?

Ahh Ruan! The headbolts.. was it yourself who mentioned something about cheaper alternatives to arps or did i make that up??

oh wait, the left IS Hdi :|

n0v0s Wrote:oh wait, the left IS Hdi :|

I was getting worried that you had maybe confused left and right for a minute there, yes I am very sure

sweet, cheers for that. the hdi rods do look more robust. are they the same length? and is it just the main bearing shells the are needed to stick these on an xud crank?

and has anyone else broken or bent a hdi rod?

Brynllwynog did... But darrens snapping imho wasn't to do with power... But that's a whole other story...

Me and Dave are having a set made, but well see about what happens with them, whether theyre any good and let you know...

having a set made? as in forged rods?

No, head studs.

Forged rods are not the be all and end all of reliable xuds, mines been on standard rods running 300lbft+ now for over 22,000 miles and they've not gone yet...

Ruan Wrote:No, head studs.

Forged rods are not the be all and end all of reliable xuds, mines been on standard rods running 300lbft+ now for over 22,000 miles and they've not gone yet...

Famous last words Ruan

If they go, they go...

I can get x5 engines for the price of a set of conrods....

I could spend my life changing things to make it apparently more reliable, but by the time you've done, you've spent what you would have done on a few more engines... Which inevitably you break things on...

If you're doing cheap tuning, keep it cheap... The best rule is to only buy expensive items if they are car unspecific... The most I'll spend that's not car unspecific is on the head studs...

Yeh this is exactly how I do tuning, keep it cheap... I have HDI rods in, with a little over 1.1mm off the top of the pistons to drop compression and the thinnest gasket to help it from blowing. The studs shall prove interesting, hopefully at above 12.9 grade+ should be a difference over the 10.9 stock bolts, but also could mean that they wont need to be replaced after ever head pull, also makes dropping the head on alot easier

In my opinion you will struggle to break the HDI rods, they are much wider where the DT rods normally snap, and theres many theories behind darrens hdi's snapping, but lets not forget he was running some silly boost/advance and pushing to 7k. Just my opinion on the subject though, am gonna make an effort to kill them now though... hehe

Ruan Wrote:If you're doing cheap tuning, keep it cheap...

the xuds theme tune!

Any idea on a rough price? Is there anything to stop one from removing/replacing each individual headbolt one by one for an upgraded one whilst maintaining headgasket seal? In which case i'll wait for the engine bay to go orange again before upgrading..

Need to spend the money on an decent egt gauge instead nowish or its not going to arrive in time Dragon gauge spessshal ..must...resit.

Dave Wrote:In my opinion you will struggle to break the HDI rods, they are much wider where the DT rods normally snap

I wish you hadn't said that Dave! I was staying focused on being all conservative. Sounds like a challenge! :nope: Now if i can just make up a win pump to fuel my turbo..

Dave Wrote:am gonna make an effort to kill them now though... hehe