callum,

I would agree with you on the 5speed statement. andy has found the UK gearing suited the 1/4mile best although I find second gear a bit too high on track hairpins and mini round-a-bouts, with a 2litre.

with the UK classic 5speed, jb's 2.5 with 20g felt spot on for everything IMO. there was a really nice spread of gears.

steves car with short gearing but high rev limit felt like it was as good as it gets for a flexible all-round 2litre. a classic UK gearing would possibly help on the 1/4 but IMO probably spoil it on the track/round-a-bouts.

we will have to see but I think the 6speed's first 4 gears, is going to be a backward step with the 2.5, especially for standing start and lazy type driving as you call it.

[Edited by T-uk - 1/1/2004 7:03:19 PM]

 

Andy
It all gets confusing doesn't it? all these variations between models/years, so and so on.

So whats up with the std rods/pistons on the 2.5? {Asking cause Subaru designed the engine as turbo application, surely they would be as good as the 2.0 rods/pistons were for the 2.0?}

Alan

 

Alan

There may well be the same safety margin on the Sti 2.5 as the UK 2.0 but nobody is running a 2.0 UK over its oe rpm limit AFAIK, they are running them well over the power output yes but the concerns regarding power output on the US Sti are the very tight piston clearances (less than 1 thou)

Andy

 

Are there any other engine manufacturers do you think using the same materials as Subaru use for the US 2.5 pistons (rods?) which may help dispel the reservations of running higher rpm with such a tight clearance?
I had never came across or heard of this hypereutectic type piston (what is this?!) before now, so wondering if it's just advances in material technology?

 

my own "gut"(as I'm not a technical type) fear , would be the rod failure running over 7k on the 2.5 block. loosing a bottom end is bad but mincing a head too

 

Alan : Subaru designed this engine for the American market and 300 bhp. As I understand it, the pistons have a high silicone content and this is supposed to give them a very low co-efficient of expansion. As Andy says the clearance is less than 1 thou, in fact Matt Clark has measured the standard piston and bore clearance and had one with 1/4 thou clearance so the concern is that when these engines are subjected to a lot of heat (read plenty WOT) there is a possibility the piston will nip in the bore. Unless this new piston material has wonderful properties as opposed to the product of an advertising executives fertile mind then I think this must be a real possibility and I think the pistons are a weaker link than the con rods.
I recon than anybody building one of these engines with Omega pistons and arrow rods will have a pretty durable motor. The semi closed deck blocks are already proven and there is no history of crank failure.
It will be interesting to see how John gets on with his 2.5 and as Andy said it may be proven that these engines are good for far more than the specified figures just like you have found out on the UK engines and I have already shown on the JDM open deck block.

[Edited by harvey - 1/1/2004 11:26:37 PM]

 

I agree with John here and it comes down to whether you can afford to take that gamble or not. Buying one 2.5 block is costly enough but two would be a complete nightmare. Reputable companies will never under spec a build and having it overspecced is good insurance IMO. This is not to say that standard 2.5's will not produce exceptional results, in line with those from the 2.0l's, but they will need TLC & there may be tears along the way

 

agree with harvey, that if you are leavng the factory rev limit, the pistons will probably be weaker than the rods.

clasic UK V STI JDM with similar mods , can get peak figures very close together, as even the JDM peaks before the UK's redline. the trouble IMO is when you want as flexible a set-up, with high revving engine.

 

Basically someone needs to crank up the boost and try it (JB)
After all it wasn't that long ago that the 'clever people' in England told me that rods will break at more than 300lb-ft on std internals and that for anywhere near 400 bhp you would definitely need uprated internals to avoid a major failure
IIRC Harvey, that ODB you are running is only any use up to 350bhp then it will split liners or blow gaskets

Andy

 

Harvey, Andy..
Which is why i posted about what other engine manufacturers might be using as materials for their components.
I hear what you are saying about the engine (2.5) being designed for 300 BHP, but of course, there will be scope beyond this power level, since Subaru, or any other manufacturer for that matter, won't design an engine and market it to the public through fear of warranty claims on engines made to produce power close the design limit of their engines.

Having said all that, where the wobbler gets thrown in as far as i see it with Subaru, is the design / capability of the gearboxes...

Alan

 

JB will not be able to resist for very much longer now that the Safeguard is working 1.8 sounds like a very nice number

Andy,
Do you not think that your rods could easily have bent at just over 300ft/lbs if you had not taken great care to avoid det or had run too much timing? Not saying you shouldn't be proud of your achievements just that others should not overlook the mapping skills required to do this sort of thing "safely"

cheers,
callum

 

Possibly Callum, although bad tuning will also kill a 250bhp engine quite quickly !
There are over 10 cars out there on std internals all running around 400bhp/350lb-ft......and I only mapped a couple of them !
The 2.0 engines reported to be throwing std rods at 300lb-ft+ were 'supposedly' professionally tuned !

I'd be prepared to hike the boost/torque/power on a std internals 2.5 but would not move the rpm limit. I once broke a set of cossie turbo rods on a N/A 2.0 running under 200bhp (they are fine on a 400bhp cossie) this was due to running to 8krpm, cossie limit 7k

Andy

 

Andy:If we were sheep and folowed/did what the "experts" down there recommended then nobody would have broken 400bhp and still had a working engine.
I am told a few of the "experts" are rubbishing my figures but amongst themselves and not on the public board yet. No doubt one of them will get brave behind the key board soon. This is despite the fact I have already posted that I am happy to go back to back with Rannoch at Well Lane, the nearest rolling road to us both, in the early part of this month before I do other things with the car. There was also speculation about the RC Developments car being more powerful but when the gauntlet was laid down for between Xmas and now it all went silent.
I think these clowns should put their money where their mouth is.

It is down to John now to explore the limits of the standard U.S. bottom end and I hope for him it is well past 450bhp as he has had more than his fair share of problems with his turbos, engine and now gearbox.

 

JB will be wanting to go for an MD304 then, since this is capable of running 1.8 bar !!!


Alan

{disclaimer} Allegedly

 

Now who is telling lies?

 

ROFLMFAO

if he needs to do the rods and pistons, to lift the rev limit and stretch the 6speed gearing, he might as well do a harvey turbo too and really liven the top up

[Edited by T-uk - 1/2/2004 1:17:31 PM]

 

do people think there is enough "meat" in the US block for 1.8bar?

 

Andy,
I came to the conclusion a long time ago that "professional" only means "trying to make a living at" and I'm not talking just about car tuning

Harvey,
I wish I could package and flog your tenacity, it would be worth a fortune Speak to you soon and good luck with your new projects in 2004.

cheers,
callum

 

The problem with "meat" John is that the blocks are dimensionally the same externally, which means that because of the bigger bores, there will subsequently be less "meat" for the block, but to counteract this, the block is of a semi closed deck design, so would imaginr block strength to be similar to an open deck 2.0.

It's open to debate though as i don't know the answer for sure.

Alan

 

I spoke to Chris at G-Force about block strength some time ago and he suggested that APS would soon(?) be releasing inserts which would improve the 2.5 semi-closed block. I am not suggesting these are required as I haven't got a clue, just passing on the info. Again it could just be over speccing but they appear to have been building engines to circa 650. They are running the standard block at 468 with plans for more by the look of their website - see here

APS 2.5 results

It looks like the Americans are achieving good power increases with mods that don't involve really high boost? I assume that larger turbos like the GT30R, exhausts, inlets, etc. are providing the power gains rather than high boost. Is this practical ie 400ATW with 1.2/1.4bar boost levels?

callum

 

I would not have any quams running at circa 1.8 bar if that is the optimum point in the boost v ignition advance equation. With the bigger cylinders the optimum boost may be less but I do not have enough knowledge to know in advance. It would only become evident from trial and error. I know 1.8 bar is a lot for the bigger cylinders but I would be very surprised if it were a problem area and I think the standard pistons will have proved the weak spot before then.
In the early days with my current engine I ran at 2.2 bar for a while and then tried numerous other settings down to 1.5 bar which was OK but then settled around 1.8/1.85 bar. No point running boost for the sake of it although a little extra has a noticable effect on torque.

Callum: Thankyou. I might have a less tenacios approach if I had not been crossed thirteen months ago which was a bad thing and separately been put to a lot of time effort and inconvenience because of lies etc from a particular supplier. At that time I was relatively new to the incestuous Scoobynet World. It seems to me that some companies in the Scooby supply chain make wild claims, have nothing to back up their "expert status" and cause a lot of grief and disappointment along the way and people without the knowledge are often taken in. Even more knowledgable guys have had a bum ride.

 

There all at it!!

One instance, he made claims the handbrake must have been used to "up" the drag on the rollers which will give better figures, also atmospheric temps were like what the Bahamas are seeing just now and not expected UK temps, i.e baltic.
This was for a differnt car mind you, not your's Harvey, but I can see where your coming from


Dont know why it's so unbeleivable, could it be that it makes them look incompitent!!

 

OK then I wonder if my turbo is big enough to run 1.8 - just in the interests of science. I might have difficulty persuading Bob to try it first time out though

At the risk of showing my lack of Scoobynet etiquette and ruining T-uk's thread I'm interested in learning about gas flowing, particularly how to do the inlet manifold and maybe even the turbo. I need an idiot's guide - can anyone point me in the right direction of useful info please? I've done a couple of sets of headers and am armed with a die grinder which could be considered dangerous

I will gladly move this to another thread if anyone is offended.

cheers,
callum

 

If the handbrake was used to "up" the fgures, why is so much emphasis placed on flywheel figures?
IMO, "at wheels" figures provide the comparison, as that is what is measured by the equipment. Flywheel is then calculated using recognised ISO procedures taking into acount temperature variations.
What popular rollers in the UK only give flywheel output?


What car are you referring to Scoty?

Alan

 

Callum
I know this thread has developed into something totally different to the original posters request, but a lot of interesting discussion without malice is coming out, so i for one am interested in keeeping it going and learning more.

Alan

 

Callum, since Matt Clark is building the engine and using the rods and pistons he is I will be quite happy to peak yours at 1.8 and hold 1.6 at least for as long as it takes to establish wether its happy or not. My gut feel says it will be. I will be going the same route mid this year as i'm not going to bother going internal on the STi9 engine and then I will be looking to run the same boost as the STi5 at an 8k rev limit, if it breaks it will break but we all flinched when we started to run 2 bar on 2 litre engines and they seem to hold together ok. Pistons will be key to this.

Bob

 

Callum
I'm a bit lazy this way, looking for stuff on the internet. Any links to achieved results by the Americans?
Cheers in advance.

Alan

 

Callum: Porting the heads is far more involved than doing a set of headers and to get proper results there is a fair bit of development work using a flow bench. Best to do heads an inlet manifold together. I have already had the development work done for my next 2.0 litre engine(using a pair of scrap heads donated by Matt) so part of the cost is already defrayed. I suggest you let him give you a price for this work as doing it yourself could be very hit and miss. Give me a ring if you want.

 

Hi Bob - I didn't think you would bother with these provincial forums just goes to show you never know who's watching...LOL

Alan,
Some of my good links are on my other PC - I'm supposed to be working today haha. Try these for interest and I'll see if I can find more later. If it's not the stuff you wanted just shout.

NASIOC 2.5 @ 375WHP

NASIOC-APS 468 crank thread

NASIOC 2.5 Shootout

edited to correct the links

cheers,
callum

[Edited by Callum Ferguson - 1/2/2004 4:14:18 PM]

 

Harvey,
Thanks for the reply. Apologies if I implied that I thought I was capable of doing my heads just because I'd ported some headers. Matt & I have discussed the heads and there is a plan developing

There still seems to be a lot of peripheral porting and "polishing" going on. If it was practical, read simple, to match the manifold to the injector housings or to port the throttle body to the manifold then I would be keen to give it a go. I've been inside my throttle body already, again I'm not insinuating that I'm competent, just enthusiastic I understand that there is polishing for eyewash and also porting stuff that may help the engine breathe. Porting the headers is simple because there is a soot or gasket line to follow but what about some of the other parts?

regards,
callum