Any reason for that Mark, are the 2.33 ones beefier or just a poorer design? I dont have my 97.5's to hand as Im away. I assume we are talking Wiseco here?

Cheers

 

Conrad,

Yes they're custom Wiseco's.

The 2.35lt forging (97-98mm) is a little heavier, than the latest 2.5lt forging.

I'm loathe to change the 2.35lt piston, because it's more than proven itself, and the 2.5lt forging is also working really well, and has so far been tested to a tad over 800bhp in the US.

Seems pointless changing something that works so well.


Mark.

 

Excellent commentry as ever. So interesting, but some questions (you must be getting tired by now..)

CDB
Machine to 2.5/liner/piston etc.
Open my Sti v3 heads (or buy some)
2.5 crank.

Now that turbo: Does that have to be twisted or is there enough room for it in there? (I suspect not).

Time to think about the gearbox, but that is for my hillclimb thread, this one is too good.
Graham

 

Also interested in the twisted turbo set-up, is there a before/after comparison available using the same turbo with the two set-ups? Fundamentally is the additional investment worth it (headers/up-pipe/downpipe) or is the main benefit the wider choice of turbos that can be utilised in the twisted position?

 

there is no turbo that compares to the twisted for huge power !!!plus i think adding a twisted turbo has more costs than just headers etc ??

 

I undersand there are 3 basic reasons for twisted:

The big turbos will not fit in the 'convensional' position unless inclinded to clear the engine/brake servo etc
The inlet to the turbo can be straight and direct compared to twisting round/under the inlet, and much bigger in diameter to suit these large turbos.
The remote waste gate of the special turbos can be fitted easily (easier)

Oh: they look sexy when the bonnet is open!

Drawbacks are I guess the usual ones, hard to do the above, and costly to do.

There are good pics on the Scoobymania web site.

Graham

 

What do you mean by a twisted turbo?

 

Alan Bell's turbo isnt in a twisted setup, its in the OEM position. It's a tight fit, dont get me wrong, but it sits in the OEM position.

Going the twisted route, gives so many more options available in terms of the the sizes of either exhaust housings, or compressor covers or cores, the options are pretty extensive.

Just going that route "for it to look nice" would be a backward step IMO. It has to be done for power reasons. By the the time you have revised the intercooler pipework, flipped the alternator, turned the manifold, etc, etc it adds up!

 

Twisted so the the entry to the turbo is pointing to the drivers wing, rather than the power steering pump.

 

Thanks Steven, I suspected Alan's engine was 'conventional' iyswIm, and all the more interesting as it simplifies the 'stage One' build.

Oldfella (should be my 'name') there is no substitute for Cubic Inches!
With the cost of liners/pistons/crank the same for 2.5 or 2.33 then why not go to 2.5? (uprated rods in both) AND get the benefit of the secure CDB?
The fact that Alan's car makes an Accountant sound like a TV presenter (just a joke Steven) with a 'straight' turbo sounds even better.
On top of that is John Stevenson's hillclimb experiences....

Sorry if i have 'twisted' this thread selfishly, but I guess some of you are thinking hard now.

If Alan is reading this: any chance of a pic of the engine/turbo please?

Graham. (hoping the bonus comes in soon)

 

Dont know whether you will get pictures from Alan, hes not fully it literate Although i am sure he will do his best to acceed to your request.

Me, a TV presenter! you have clearly never seen any TOTB DVD's

Mike (Oldfella) looks a damn sight older than you Graham, not sure wether he is though . I would also guess that Alan could give you a run for you money in the age department

Although Alan is just a big kid, like all of us. His number plate slogan sums his character up nicely; "Life begins at 450BHP"

 

opposed to me who is a kid, or trying to convince myself I still am!!

27 in January

Hmm think I should move out of my parents before 30, but the garage is just

David

 

Very interesting thread as i to would like to go for a 2.33/2.5 conversion in the future, probably with a TD06/49lb Garret turbo and some ported STI 6 Heads, my target would be a 400-450 bhp road car.

Someone posted this link in the Wales section any opinions on this: (Converting a US 2.5 block to a CDB)
Subaru Block

 

It can go horribly wrong if not done properly..

 

David, is that a semi open or open block ???? > Steven did explain > but its a age thing ???? (LoL)

 

Alan, its a semi

 

Some other things regards 2.33-2.5. There is more friction on the ring pack due to the lager bore, and the flame has further to travel to complete its combustion path. Smaller bores tend to take more ign timing due to this and timing plays a big part in the crispness of the engine making the motor much more lively. The bigger the bore the more chance of det or pre ignition, this is when you get two flame fronts, pre ignition being the one that occours before the plug fires from the outer part of the bore and when the plug fires you create the flame front you want. These two flame fronts collide and you have det. I have been working on three levels of combustion chamber for the 2.5 bore and a design of piston that will allow more ign on this size bore. These will be available very soon. The downside of this is that the more you push to redesign you start to loose the ability to get complete combustion at lower rpm resulting mainly in poorer fuel consumption its always going to be a compromise. I have also done piston rod combo that uses a 2mm longer rod on the 2.5 this took some thinking to be able to do this and retain a strong piston with the highest spec ring package but its done. The extra lenght gives a more prefered rod ratio this also helps the engine to rev, as an extra its better on the bearings. Over winter i will be doing some crude but hopefully effective mods to the EJ257/25 that will not kill the pocket and will be able to take 500/500. This will help but not cure the fact that the bores hollow in service, even more so with the extra power although it will (he says) increase gasket life.
The wieght of the mahle powerpak piston is:
99.5mm piston 383.8g piston/rings/ strong pin 4.8mm wall/clips 583g.
Also soon to come will be a 2.3 engine with linered 2l block or modded EJ257 75mm stroke 99.5 bore and option of 2mm or 4mm longer rod this should rev! Remember you heard these mods here first.

Hope this has made interesting reading.
Steve.

 

Need to have a chat with you at some point steve

Any chance of posting them bits too

 

David

No poblem, I can post them or give them to Pat on wednesday?

Steve.

 

Steve, very interesting and informative. Thank you

Mike



PS. Steven, I had a terrible paper round

 

I didn't have a paper round, too busy making model aeroplanes to fly (ish) over in the Dell in middle Birmingham.
I think that hobby involved a lot of solvent abuse as the dope was overwhelming!

Steve/SMG Very interesting input indeed. You do indeed learn something new every day. Glad to be doing my engine later rather than sooner when the proto bugs are ironed out.

This is the best thread on Snet by far.(imho)

Graham

ps: #194 Stress cracking?

 

Steve, Just give them to pat thats fine

PS Steven, that is an Open Deck Block that has been welded!

 

David, i know, but its not fully closed is it.

 

No, but its not a true 'semi-closed'

Its an open deck block that has been modified.

 

Graham, im going to be looking into getting a set of IHI / TD series rotated up & down pipes made for the very reason of keeping the FMIC pipework tidy and to a minimum length. A nice straight inlet to the turbo should help matters too and open up the options when it comes to turbo fitment too.

I have the contact details of an exhaust specialist in stafford that is currently making a custom 3 inch down pipe and some other bits for a friend of mine with a celica GT4 with a garret GT28 on it. I'm waiting to see the finished quality before approaching him but i have been assured he is very resonably priced. I will definatley see what sort of deal could be done on a few sets of them.

Dan.

 

Danny, if your going to the trouble of twisting the turbo, you may as well get it done with proper Garret flanges, as that opens up a new world of turbo availability.

 

Not exactly...

Incorrect thermal cycling when the bores liner support walls were welded to the outer casing. Once built up and running on the dyno the bores continued to try and move when the engine was at full chat and then the liner and wall failed where they couldn't move, ie where they had been joined by the welds.

 

Thanks Tim, and thanks to Danny too.

I find it interesting that John Stevenson's 500 x 500 hillclimber has been difficult to drive on the track and he can actually drive an Impreza...so something a bit more 450 x 400 could be closer to my 'level', so I really like the idea of Alan B's turbo 'straight' to the engine.

Danny: I hate the long bling FMIC pipes and the inefficient looking 180 degree bend from the turbo, so this is to be done over the winter to shorten/straighten everything.
Who sells the AlanB turbo's? (MD 321T)

Graham

 

its from lateral !!! im sure

 

yep.