Could somebody please educate me on this?

The new STi has a semi-closed deck block and I was wondering whether this had the same kind of strength as engine blocks that people such as Craig H had and therefore able to take boost's of around 1.8 bar or maybe more.

Damian.

 

A semi closed deck block is a little bit less closed than a closed deck block. And a little bit more closed than an open deck block.

An open deck group N block has no problem running at 1.7 bar.

 

Pete,

In that case does that mean the new STi has huge potential for running some big power (i.e. 400bhp+) and high boost?

Damian.

 

no. (sorry, not pete)

The block is said to be quite happy in open deck form.

hyperex runs almost 500bhp and 430 lbft on an open deck block.

Those who are seaking to build monster engines tend to want to strangthen everything and erase all potential weaknesses so in this respect a close deck block is preferred but not necessarily necessary.

The weakness with stis etc is the con rods which are the same as all other impreza conrods. The sti forged pistons (learned other day that sti 5s have been known to have cast pistons ) can take a lot of boost, but they are not the limiting factor.

I would also like to set the straight that it is uncertain which cars cam e with closed deck blocks. The only car we know for sure that always does, is the 22B, and those blocks are as rare as rocking horse ****.

 

Adam,

Thanks for the response (and Pete).

The new STi specifically states it has uprated rods and pistons. So I'm presuming here that STi have took on board what bulletin boards such as this have posted and uprated them.

The reason I am asking these questions is I am in a bit of a dilemma. Should I throw money at my MY00 and uprate that? Trouble with that is when it comes to be sold all of the highly modified cars I have seen have been returned to standard and so a lot of money is lost. My alternative would be to save up for say 12/18 months, sell the MY00 and get a new STi which already has uprated internals.

Damian.

 

I would have no trust in what suabru call uprated internals.

You never know what you are getting or what it can take.

The only way to do it safely, is to choose the bits and get it done yourself.

You never recoup your costs when selling a modded car, because either people dont trust it, or they want the fun of doing it themselves. That is why after any mod I do to my car, I retain teh original.

Ultimately it doesnt matter in my case as I wrote off the money for the car when I bought it knowing I would never sell it. It has also lifted all my fears of doing what the hell I like to it.

But even though I am not selling it, I know that if I get annoyed by huge power, or unreliability, I can take it back to an uprated standard (engine is out anyway, so may as well spend extra 1.5 k on internals) and sell off the bits needed for monster horsepower.

 

Which model and year of imprezza came out with a closed block as standard????? anyone know?

 

From the NSW WRX Club:

Open Deck:



Closed Deck:



[Edited by dice - 3/5/2002 6:38:30 AM]

 

Dice,

Thanks for that. I had seen a picture before comparing an open deck to a Semi-Closed deck and you have now completed the picture for me.

I have to admit that I don't know anything about engines but to me the open deck looks like it is built like that to aid the cooling properties of the engine. Whereas the closed deck will struggle to lose it's heat. I don't know whether that is a good or bad thing?

Damian.

 

There probably is slight temperature issues, but more likely it comes down to ease of manufacture, and hence reduced cost.

I doubt they would make it as strong as it is if it wasn't for rallying.

What we need to do is lobby the FIA (or whoever the governing body is for WRC) to change their rules so the WRC cars can run unlimited turbos, but a standard block, pistons and rods. Then they would make it strong Or even better, say it has to be a 2.5L engine....

And run standard transmission bits, and must be for sale at less than £25K...

etc etc

Gareth

 

Gareth,

I was just about to reply about it also being available for the road until I saw your last sentence.

It's a good idea.

Damian.

 

LOL! That's a classic one! "The new STi specifically states it has uprated rods and pistons. So I'm presuming here that STi have took on board what bulletin boards such as this have posted and uprated them."

I can just see the guys at STI reading these bbs's and using basing the further development of the car on them. So does this mean we get a trunk monkey as standard from the STI 8 onwards?

bbs.22b.com


[Edited by MorayMackenzie - 3/4/2002 2:13:21 PM]