Hey all

 

Ok got the stage 2 turbo's comming next week. any engineering company i speak to tell me that i should put forged pistons in to the bottom end. but i guess this also means i have to put stronger conrods in.

 

do i have to do this to accept higher boost and stage two turbos? the bottom end is fine and i might be bying another which is fine to work on.

 

Just afraid that i might be being told to buy something i dont need!

 

Latz

 

PS i take in to consideration that there is no definate way to say if my bottom end will take this. i just wanted your opinions

 

[This message has been edited by Latz (edited 20-02-2002).]

 

 

[This message has been edited by Latz (edited 20-02-2002).]

From what I have read, and read of people doing, mostly on TTnet, the stock bottom end (pistons, crank, conrods, block, bearings), in good condition, is capable of holding at least 650bhp (crank).

 

So unless those are some serious 'stage 2' turbos.. They're talking bull..

Thnaks aaron

 

nico reckons the crank can hold about 800 bhp odd, but just wanted to know if the pistons would start to melt or deform?

 

Last thing i want after pulling all apart is the F**** conrod to come through the side of the block or the piston to crack!

 

Thanks

 

Latz

 

[This message has been edited by Latz (edited 20-02-2002).]

The stock rods and pistons are supposed to be very strong as well so im told. You could get the rods tuftrided and you can buy a ceramic coating kit from demon tweeks that is supposed to allow the piston to take much more heat.

Just things to consider when your stripped down that far

The problem with the stock pistons is that they cannot withstand severe detonation for long and this is what destroys them.

 

The key to this is to alter the fuel management to compensate for the additional airflow that the stage 2 turbo's will provide and look at the cooling of the intake and maximise the flow of exhaust.

 

I opted for forged pistons as a safety measure even though I have larger injectors etc.. and I have previously damaged #6 piston after running 18psi on stock injectors, pistons and intercoolers.

 

PS. Forged pstons also do not like severe detonation although they can withstand it for a slightly longer period of time.

 

Steve

Hi Latz,

 

My opinions are with SteveE on this one. I too have got JE forged pistons - since they can take more pre-detonation (should you allow it to happen). I believe you're more likely to puncture a hole in forged piston, as opposed to shattering a cast one. (Less damage for the whole engine - should one go!)

 

As everybody else said - crank: top quality and conrods - also top quality.

 

Rods are generally more expensive than the pistons actaully - just something to bear in mind if you're reaching into your pocket.

 

Simon.

Steve what boost can you run now you have the dual pop and large injectors?

Cheers

Paul

Paul,

 

The stock turbo's generally run out of steam after around 16-17psi.

 

I managed top get a higher boost pressure on the gauge but I think it actually made the performance worse.

 

With upgraded turbo's 17-21psi acheivable and the HKS/Greddy/JWT turbo's will run an easy 24psi.

 

There are people on tt.net claiming that the 555cc injectors are only good to around 650-700bhp. Then then next upgrade is 720cc injectors.

 

It all depends on compression. Stock compression is 8.5:1 and with the stock turbo combination 17psi seems to be the max when you have the filters and injectors.

 

Higher boost ie. up to 21psi requires the compression to be lowered to around 8:1 otherwise the engine will probably blow (head gaskets first)

 

Boost pressure isn't everything though. A larger turbo will flow cooler and therefore denser air at 1bar boost presure than the stock turbo will and therefore create more power at the same pressure.

 

Steve

 

[This message has been edited by Steve E (edited 22-02-2002).]

Hey guys

 

Steve, i have got the HKS AFR to alter the air and fuel ratio will that do?

 

i rang demon tweeks today Paul, and they said they never heard of the cerami coating kit?!!!! i expected that from them though!

 

So whats the final verdict guys? standard or uprated bottom end??

 

Thanks

 

Latz

IMO the stock internals should handle stage 2 turbo's providing you not planning on running much more than 1bar or WOT for long periods of time.

 

If you wanted to run at 160mph with stage 2's; say for a full tank of petrol, then this would put the engine to the test and I would advise running with the forged pistons etc.

 

I know a Z running at the track last year than was running dual intake, exhaust, high flow injectors and 16-17psi on stock turbo's. Within 5-6 laps around the track, he melted a piston.

 

It's your choice but once your revs are past 4500rpm it doesn't leave you much safety margin when detonation starts.

 

I don't know how your HKS fuel controller works but it can't flow more fuel at WOT.

 

Steve

 

 

[This message has been edited by Steve E (edited 23-02-2002).]

Hi all

 

thnaks for the advice steve. what does WOT stand for?

 

i think i am going to have to do the bottom end as i am in the true sense, a driver. theres not many cars that have lived past me and i mean engine wise!

 

thanks for all the help and info guys!

 

Latz

Good choice!

 

WOT = Wide Open throttle