Wiseco pistons + Cometic 1mm + std. rods

[GreddyMR2]

Hi,

I am rebuilding the engine and would can take wiseco pistons for a good price.

I would like to ask, if it's nothing wrong with fitting these pistons with standard rods?
They are: 86.5mm and 9 CR.

Also, I have a Cometic 1mm head gasket and it should be 9.2 CR when fitted. The stock is 8.8.

My plans are just to raise boost up to ~1bar.

What about compression ratio? Isn't it too high?

Thanks

[bobhatton]

Hi,

I am rebuilding the engine and would can take wiseco pistons for a good price.

I would like to ask, if it's nothing wrong with fitting these pistons with standard rods?
They are: 86.5mm and 9 CR.

Also, I have a Cometic 1mm head gasket and it should be 9.2 CR when fitted. The stock is 8.8.

My plans are just to raise boost up to ~1bar.

What about compression ratio? Isn't it too high?

Thanks

Yes way too high.
For 1 bar boost you need 8.0:1 compression ratio

[GreddyMR2]

8.0? Really?
So what is the solution if I take those Wiseco pistons?

Why then for standard pistons (8.8 CR) 1bar boost is OK?

[bobhatton]

8.0? Really?
So what is the solution if I take those Wiseco pistons?

Why then for standard pistons (8.8 CR) 1bar boost is OK?

1 bar boost is not ok for 8.8:1 , you will be working off the knock sensor all the time unless you run high octane fuel.

I would use Wossner 8.0:1 pistons, the Wiseco pistons are designed to be used with racing fuel in the USA.

[ashley]

Just to present another point of view...

CP pistons at 8.5:1, with a bit of head work that'll come down a bit, fine with stock rods

8.0:1 for 1 bar of boost.....not for me, maybe for 2bar

[bobhatton]

8.0:1 for 1 bar of boost.....not for me, maybe for 2bar

Never on road fuel, that would only work with high octane fuel

[ashley]

8.0:1 for 1 bar of boost.....not for me, maybe for 2bar

Never on road fuel, that would only work with high octane fuel

Except that, as you are aware, it does work on many proven builds already Bob.

And...as stated it's an opinion:

Just to present another point of view...

Peace out

[GreddyMR2]

Hmm, so there is no one proven opinion...

Fuel would be 98 or 98E15 (15% ethanol).

Let me ask differently. I have 2 options:
1. Leave stock pistons with Cometic gasket.
2. Buy wiseco for ~100gbp and use wiseco.

So, which should I choose?

[ashley]

If it was me I would use 8.5:1 pistons from CP

[bobhatton]

8.0:1 for 1 bar of boost.....not for me, maybe for 2bar

Never on road fuel, that would only work with high octane fuel

Except that, as you are aware, it does work on many proven builds already Bob.

And...as stated it's an opinion:

Just to present another point of view...

Peace out

No it does not work on proven builds.

To stop detonation the timing has to be retarded and that over heats the engine, cracks blocks and losses lots of power.

The correct facts need to be stated, not opinions.
There is far too much wrong information past around forums like this and anyone reading it thinks the wrong info is correct when it is not.

[bobhatton]

Hmm, so there is no one proven opinion...

Fuel would be 98 or 98E15 (15% ethanol).

Let me ask differently. I have 2 options:
1. Leave stock pistons with Cometic gasket.
2. Buy wiseco for ~100gbp and use wiseco.

So, which should I choose?

Do it right, fit the correct compression ratio pistons for your design of the engine.

What fuel, how much power do you want, what boost will give that power, once you know that you can work out the compression ratio needed.

The 1mm head gasket is the right way to go, add 8.0:1 pistons and your engine will be good for 450HP with the correct size turbo boosting to 1.0 1.2 bar boost, injectors and aftermarket ECU.

With stock Rev3 ECU and CT20B turbo running 1.2 bar boost you would be around 330 HP and the knock sensor will not be retarding the timing and over fuelling the engine. We have done this many times now and it works very well.

[RyanRs]

So bob, if the main aim of the game is to make some bhp numbers... then why does it make any difference whether you use a low CR / high ignition advance or a higher CR/ lesser ignition advance? You can cool the head with extra fuel. Tbh the only real advantage i can see is in the MPG! I've made 570bhp @ 2 bar on V-power & 8.5:1 and yea, it didnt have much ignition advance, but i much rather it how it is now than 400 bhp and full Ign advance as you suggest?!

[ashley]

Everytime we talk about static compression ratios we fail to have a real discussion, it is ALL opinion with no proof one way or the other. I respect Bob's reasoning for significantly dropping CR's to run more boost, but there are so very many modern tuners and builders doing exactly the opposite with great results (11.1:1 and 2.2bar of boost anyone?)...until we get an expert from each side to have a public discussion about it we'll be left with threads like this and no one knows which way to jump.

Personally I think you have to go on real world results which suggest that 8:1 CR is fine for 2 bar of boost, and following that reasoning I can't see why 8.5:1 would not be fine for 1 bar of boost.

Peace out

[jasongtr]

i think mine was mapped at 1.8bar with cp pistons - built 8000 miles ago and some 6-7 years - still going strong

[GreddyMR2]

Hmm, so there is no one proven opinion...

Fuel would be 98 or 98E15 (15% ethanol).

Let me ask differently. I have 2 options:
1. Leave stock pistons with Cometic gasket.
2. Buy wiseco for ~100gbp and use wiseco.

So, which should I choose?

Do it right, fit the correct compression ratio pistons for your design of the engine.

What fuel, how much power do you want, what boost will give that power, once you know that you can work out the compression ratio needed.

The 1mm head gasket is the right way to go, add 8.0:1 pistons and your engine will be good for 450HP with the correct size turbo boosting to 1.0 1.2 bar boost, injectors and aftermarket ECU.

With stock Rev3 ECU and CT20B turbo running 1.2 bar boost you would be around 330 HP and the knock sensor will not be retarding the timing and over fuelling the engine. We have done this many times now and it works very well.

No no, I am not aiming to huge powers.

Stock turbo (CT20 with a bit bigger impeller), stock fuel management (piggyback maybe to correct AFR), just main mods, as intake, exhaust, IC, also cam gear on exhaust cam. Nothing major.

Aim is to reach reliable ~280hp (about a limit on rev1 probably).

So the question is to leave standard pistons or fit wiseco?
No money for more at the moment.

[Super_red]

if that was my goal I'd be swapping to rev3 ecu etc on a stock block and call it a day. In fact I'd probably stick to the rev2 ECU.

[GreddyMR2]

if that was my goal I'd be swapping to rev3 ecu etc on a stock block and call it a day. In fact I'd probably stick to the rev2 ECU.

Any difference between rev1 and rev2 ECUs?

[Super_red]

I dont know enough to say 'no' but its not a fundimental change like it is with the Rev3 setup. Rev1 and Rev2 engines are built the same and have the same power with the same type of injection by there may exist minor changes between ECU's.

[GreddyMR2]

So finally I bought those wiseco pistons. Couldn't refuse them for 100gbp.

Some of you tell that the CR is way too high for road fuel and 1bar of boost.

So I am thinking of adding water/meth induction kit. Would it help reducing knock or not worth it?

[greeny]

8.0? Really?
So what is the solution if I take those Wiseco pistons?

Why then for standard pistons (8.8 CR) 1bar boost is OK?

1 bar boost is not ok for 8.8:1 , you will be working off the knock sensor all the time unless you run high octane fuel.

No, he won't.