Ive been watching the two threads about building 2.33 and 2.5 engines recently and it has inspired me to build an uprated bottom end.

Ive got a few questions though, that I could do with help answering.

I was wondering if I was aiming for around 450 bhp would an open deck block from a sti 6 be ok for this? Also what pistons and rods do people recommend. And finally would the crank from the sti 6 be ok or is there a better standard crank to use?

I was probably going to stay around 2l size, would this be ok with a gt30 turbo or would it be laggy. I would mainly be using the car for drags.

Sorry about all the questions lol

Thanks for any help.

 

The open deck would be fine, as would the standard crank.

Most aftermarket pistons/rods are ok tbh. As long as it's all built properly and taken care of, it should be fine.

The 30r would be too big for the 2 litre though. There are plenty of more suitable turbos, for 450hp.

 

I dont mind a bit of lag. What capacity would using a 2.5 crank give as this is possible I think? But then using a longer crank would affect how high the engine could rev. Would it make a big difference to the revs?

 

I think the 30r on a 2 litre would produce more than "a little" lag.

2.5 crank changes the cc's to circa 2.1.

When i said about revs, it's ment as the rods needs to be stronger to rev higher.

 

I mean that in general engine terms having a longer stroke crank normally means it struggles to rev as easy but seeing as it would only make it 2.1 it cant be that much longer. i didnt realise that.

I had a 2.0l with a GT2871 before and that would produce full boost (25psi) at about 4500rpm. Wasnt a subaru though it was a rover, but would it be much worse than that. I wouldnt mind that too much as long it doesnt drop off boost when changing gear from full revs.

But it sounds like a 2.3 or 2.5 would be a better bet

 

Not sure what the 2871 is like, but i know everyone has different ideas about what they prefer.

I just think you could find a turbo that would produce full power earlier than the 30r and still make power all the way up the revs.

If it's mainly for drag, then i'd suggest concentrating on making the engine able to rev high and maybe get the gains of a larger turbo, like you were thinking.

Something like an AVCR wouldn't go amiss either for when changing gear and wishing the spool was there quickly.

 

Ive seen these rods and pistons on ebay but they seem too cheap to me. Are these the real ones or some sort of copy?

Not really sure how to do a link. Hope this workseBay Motors: SUBARU WRX EJ20 TURBO EAGLE RODS WISECO PISTONS 92 (item 260052379249 end time Nov-22-06 19:13:28 PST)

 

You cant really compare how a turbo spools between a subaru and a rover, as on a rover the turbo is sat on the manifold right at the front..

As for rods and pistons I'd have a chat with mark @ lateral, you might be pleasantly suprised at pricing from uk suppliers No hidden extra's either

As for power on an open deck 2.0, harvey claims to have run 500+ for a fair few miles, I know of a couple of 400+ engines, but they werent built to last, they were built because thats what was lying around!!

a engine with forged internals is going to be stronger than one without, and I dont see the block as being a weakpoint, Id worry about the gearbox first.

David

 

Cheers, I was just using that as a rough example as thats the closest example I had. True though, with the shorter manifold it would spin up quicker.

 

Nowt wrong with them in my eye's.

 

[quote]As for power on an open deck 2.0, harvey claims to have run 500+ for a fair few miles,[/quote}
An ODB is capable of relatively high power.
The latest blocks are "semi closed deck" and may be even stronger.
I ran ODB in a rebuilt engine that went from 417 bhp to 585 bhp with continual development and a further 33K miles when I took the engine out and it was still in good condition.
index

 

Harvey,

What happened to your sti 6 wagon? Is it still around?

Dave

[quote=harvey]

 

So if I was going to build a high revving 2l is there anything else I need to think about?

Plan at the moment is to use sti6 crank or maybe 2.5 crank if I can get one, for a few extra cc's.
Probably those wiesco pistons and eagle conrods above and a rcm oil pump.
All built up in an block from a P1.

I would also be using a fairly big oil cooler as it would be high revving.

One last thing, whats the limit in terms of power of sti6 heads and cams?

Sorry for all the questions but im just trying to find out everything before I start so I dont make any costly mistakes.

 

If you decide to use a 79mm crank, and stroke the engine to 2.123cc, you won't be able to use the rods, & pistons you've linked to.

If you want to stroke the engine, you will need stroker rods, & pistons too.

If you decide to stick with a 2.0lt, the Wiseco piston in the link is not ideal. It will either give you pretty high compression, or you'll have to run an overly thick gasket with poor squish, to reduce it.

Mark.

 

Ah right,

How come they would give high compression, would they not just be the same as standard or do you mean that standard compression would be too high for my plans?

Im think a phone call to you may be in order.

 

It's a bit of an odd piston for Wiseco, and for some reason they decided to make it with a very small dish volume (9cc's) this gives circa 8.8:1 compression, instead of the stock 8:1.

High compression isn't necessarily a bad thing, but you need to be much more careful with fuel, because it's more prone to det'.

You're welcome to call for a chat.


Mark.