standard condrods

[Saunders82 0]

hello

im buzzing a few ideas about what to do about my next engine build for my golf im very much looking down the turbo route now. just wondered what they are rated too as im gonna be getting forged pistons for it will it be worth while saving for the rods, however if there rated to something silly is it worth while

scott

[FishWick 21]

Yes I would do rods and pistons if you're planning on exceeding a bar of boost.

Someone may boast of running 500+ hp on stock internals but don't take that as being a factual safe hp limit. Build the motor for it's intended purpose - i.e. boost. VW didn't build the VR6 for boost, but you can, and benefit from the extra strength in the long run.

[UnitedMotorsport 55]

As Kev says do the rods as well as the pistons to be safe.

The stock rods will hold on to 500lbft, they will bend at this torque if you treat the engine hard.

It all depends on your power goal, your setup, what boost your going to run etc.

[Kelster 0]

Kev what are doing to me? Just bought my pistons and thought I could manage without rods then you go and write that reply So before I die of heart failure at the cost this is stacking up to. Any other suprises I might need while I replace pistons and now rods ? Any bearings while I am at that might need uprating ? I don't think I am going to go above 14PSi, but you never know

[UnitedMotorsport 55]

If your not going to go above 1 bar, then stock rods are fine.

[FishWick 21]

Yep, agreed /\

12V VRTs have been around for a long time now and history has shown they hold 15psi OK with standard internals. It's when you exceed that boost, especially with BIG turbos, you're on borrowed time.

I didn't fit rods in mine when I had the chance and I'm regretting that now, but I run less than 15psi so haven't bent them....yet!

As for bearings, HPA do some uprated black coated rod bearings, which I believe are RS4 bearings. Someone else may be able to confirm.

Other than that, just build her up meticulously with new mains etc etc. I believe VW now issue 24V bearings as replacements for 12V ones, so you should be fine.

[xyber 1]

Taking a cheaper alternative first off always ends up costing you more than doing the more expensive alternative in the first place ive found in the past. Build it up so you are confident that it will take whatever you throw at it now and in the future when the inevitable happens and you want more boost

[Phat VR6 3]

the way i see it is that the rods can handle more power than the car can put down to the ground in front wheel drive format. So why change them....?

If your not going to miss the money then you might as well change them but if were honest for most people it would be a waste of money

[FishWick 21]

Famous last words. Many a 1.8T owner has said the same thing and then swiftly bent a standard rod when pushing past 300hp :-)

Whilst the stock ones unquestionably do a good job, the pistons are being pushed down very brutally compared to a Norm Asp VR6. It's only a matter of time / boost before they bend.

Stronger pistons with beefier ring lands and stiffer rods are a wise move, but not essential as you say. Just depends on your goals.

[johnODB2vr 1]

so what power figures you looking at at 15 psi ? just to get a rough idea as of power, and psi limits to using pistons and rods, wether ther stock or not ?

[Bobtrude 0]

Im running 15 psi and that is a mighty good pull!

With diff!

[Kelster 0]

I think 15psi should make around 350BHp ? I am about to (next monthish) get my engine rebuilt and am only planning 8Psi at first with a future goal of around 14Psi but am doing both the pistons and rods. For the extra cost of rods did not see the point in taking the risk.

P.S. Eek, just noticed my memberships is up, better get on it.

[FishWick 21]

Remember, it's not the boost pressure that makes the power, but rather the turbo's airflow rate. It's all down to turbo sizing. 15psi from a GT30R usually makes around 380-400hp. 15psi from a GT35R is always well over 400, sometimes as high as 450 on good engines.

[Keiron 8]

Sorry but 15psi is 15psi and at a bar of boost you will make about double the power of the car on a stock motor !

If you se 400hp at 15psi you are doing very well and I would try a different dyno ie not dynojet which read 10% high , also don't buy a gt30 they are far to small for a vr6

[FishWick 21]

Yes, pressure is pressure, but flow is something very different.  If 15psi was just 15psi, why are oil tanker turbos the size of houses?

Edited October 20, 2014 by FishWick

[Keiron 8]

Yes, pressure is pressure, but flow is something very different.  If 15psi was just 15psi, why are oil tanker turbos the size of houses?

So a small turbo could produce 15psi on an oil tanker ? Don't talk silly will a 3582 do less  power at 15psi than a 4094 ? No !

[dave_424 48]

So a small turbo could produce 15psi on an oil tanker ? Don't talk silly will a 3582 do less  power at 15psi than a 4094 ? No !

 

Flow is a more important figure than pressure, 15psi on a big turbo will produce more power than 15psi on a small turbo. FACT

[Mk3highline 287]

Agreed with above

That's why folk when hybrid ing a turbo use a larger compressor wheel to get more flow

[RBPE 198]

Bent rods are not really anything to do with boost pressure or flow, it's about the tune mainly. If you have spot on flame propagation, timing and fuelling etc on a 2bar blueprinted engine, there will be a lot less shearing and twisting forces in play during the cycle than a 1 bar set-up with some knocking due to an incorrect burn cycle! It's why a set of ARP rod bolts and a good tune can reach high power goals - 700hp+.

 

Piston rings go but again, not really to do with power or boost. If someone drives the engine cold a lot, it could wear the bore out of the cylinder more than someone that mollycoddles the engine. As such, gas bypassing the rings is more likely - same with a 120,000 mile engine than a 1k freshly blueprinted one.

 

I would personally just add a spacer plate and maybe some ARP head studs and rod bolts which ensures a better, more even clamping load for the spacer and higher tensile strength in critically stressed areas - but I would buy a second engine and build that up properly for when you go higher boost, few hundred quid for the engine maybe but a proper build for longevity would have to include, bore checking, aligning, honing, magnafluxing/crack testing etc then you've got crank girdles, billet main caps, big valve head and can soon add thousands.Just sticking new rods and pistons in, even forged, seems a bit pointless without doing the basics in engine building!

Edited March 17, 2015 by RBPE

[FishWick 21]

Flow is a more important figure than pressure, 15psi on a big turbo will produce more power than 15psi on a small turbo. FACT

 

In the same way a bath would take forever to fill up if using 15mm basin plumbing and tap

[dave_424 48]

One thing also is that a turbo is actually pretty rod friendly, its generally always in compression on every stroke since its always pushing against a pressure, even on the exhaust stroke. Whereas a high bhp NA motor has the rods being in compression and tension constantly switching which gives them a bit of a harder time

[FishWick 21]

/\ This is true.  One of the reasons rods bend is because excessive back pressure fills a cylinder and almost 'hydro-locks' the piston....and something has to give....usually the rod.   Seen plenty of S shaped ones come out of big turbo 1.8Ts that use sh1tty manifolds that don't flow enough.

Edited April 15, 2015 by FishWick