john banks

Let us not turn my thread into a Cossie vs Scooby vs Evo vs Skyline argument

I am totally serious with my plans and I believe the targets are achievable with reliability from the car complete, already specced the drivetrain stuff, finalising my suspension and engine shopping lists.

Light Blues

Let's see then!

R19KET

This subject is very emotive, and there are a lot of parameters that can influence the results. There are certain things that we can work out, based on "best case senario", and others, such as BSFC, that we need to guestimate.

IMO, you can't take figures from a rolling road, AP22, or road dyno, knowing how much they vary, and exstrapolate meaningful data, to apply to a totally different engine.

We can work out how much air an engine of a specific CC can consume, at a given RPM, and boost pressure, in much the same way we use a turbo compressor map. Of course we are guestimating the engines VE at a given RPM, but we also know what it can achieve at 100% VE, and we also know that this isn't very realistic.

Lastly, we have to try and work out just how much air it takes to produce 1BHP. I accept that 1.5CFM per 1BHP may be conservative, but only use it as a rule of thumb. APS for example quote 1.6CFM/BHP, others use as low as 1.3. I think we tend to use what works with our BHP figures, wanting the figures to be correct, rather than the other way around.

Based on the way I work things out, and applying them to two of my engine bench dyno runs, different days, different power, but dividing my estimated CFM based on engine CC, RPM, boost, then dividing it by the power, both come out at 1.42CFM/BHP (rounded to within 2 decimal places). But this is also with re-worked heads (including combustion re-shaped) cams, etc'.

As a cross reference, I'm using circa 5.6cc's/1BHP for fuel.

We haven't got enough info to "accurately" base our figure, only guestimate them. Even though the engine bench dyno is supposed to be accurate to within 2%, I wouldn't claim I have "proven dyno figures", just a set of figures produced by one method.

Mark.

ChristianR

iTrader: (1)

Andy, Bobs figure was at 2.2bar

john banks

Thanks Mark.

I think I'll need to see how it goes then open deck at up to 1.5 bar, and collect some performance values from various sources.

I suppose the one thing I might be able to extrapolate is that a 2.5 running 1.5 bar should be in the ballpark of a 2.0 running a rather more scary 2.1 bar, but I suppose even that is assuming quite a lot of things.

Alternatively, I hope I'll end up with something a bit more than fun and quite user friendly.

Based on your fuel usage Mark, I will need my 550s running at 4 bar differential pressure at least at peak power. Any more than 550 and I'll have to junk the JECS (then again maybe not since it struggles with over 550s on 2.0, on 2.5 it might tolerate 740s), so I'll try it first and see.

Using 6500 RPM and 85% VE then I might get my 605 CFM mentioned on page 1 at 1.5 bar, this with 1.42CFM/BHP might be expected to do 426 BHP, at 1.6 bar, might do 443 BHP, damn it takes a lot of boost to make more power!

Would you expect an open deck 2.5 to hold together at 1.6 bar with a few headstuds?

The info we are getting is here is so variable depending on what assumptions you use... maybe Well Lane will give me the figures I would want to believe if it will grip

[Edited by john banks - 2/22/2003 6:15:48 PM]

Pavlo

only 4 bar differential pressure?

Audi Le Mans car uses 60-80bar fuel pressure with direct injection.

I have some 850s in hand but would like to trial a 10 bar differential fuel system, as I will have the pressure available anyway (for something else).

Anyone know what pressure std 440s explode at?

Paul

hypoluxa

FWIW I'd calculated for 557cfm @ 6000 @ 1.5bar.

John, I'm not a betting man but I'd guess it would be reasonable to say that in 6/12 months time maybe you'll want more than 450... or maybe track use etc? One thing I am sure of is that you'll only want to build it once, and bearing that in mind, it might be wise to go for the full set of studs and/or the liners now. If the bottom end is stong enough, then your potential power output will be governed largely by turbo choice (simplification I know), as opposed to structural ridigity/paranoia

I read an article the other day on a Supra... over 800bhp at the wheels... on a STOCK bottom end. 1/4 mile at 160! Makes you think...

What have you decided on regarding the oil pump?

T-uk

JB,

something needs to be said.

you are ******* insane!!!!

when you first mentioned the 2.5 it was to be run at 1bar,this crept up to 1.2bar and then 1.3, now you are mentioning 1.5/6

as I said, you are a boostaholic with no will power

Pavlo

so what's wrong with running at at 2bar plus?

For ***** sake, the man was whining about 1.3bar on the std 2.0, now he's at 1.5/6 on that! Surely 1.6bar will not be enough with new rods and pistons?

But yes I know where you're coming from JB. I am still wondering about putting something really quite small on so that it's more like the audi Rs4; 400hp potential but excellent response and minimal lag (not boost threshold but that would be good too).

I'm thinking that you want a turbo that won't be to laggy, not prone to surge, but can be wound up to 2.5bar if you need to, even if it's not quite as efficient as another, bigger turbo.

Paul

john banks

Turbos and gearboxes can indeed be changed later (although I'd really prefer not!), the bottom end would definitely be a shame to redo.

The main issue with the higher boost is to reach the target I want. Had there not been a synchro kit available for this power I would have already sold the Subaru, so as honestly as I can say my present target is to make the most out of this with reliability.

Since I started breaking things on this car the fun has gone out of it, so I want to spec things that are suitable and stop there. My present feeling is that I do not want to drive a dogbox and snappy clutch daily, would rather lose 100 BHP to avoid this. Hence my projects fairly ridid requirements.

Just need to establish what I need to do this with genuine and not BS power figures. Seems there may be a good 10-15% difference between the two, but all depends how measured! I want a turbo that is big enough - too big and it will be laggy and useless low down. An Audi RS engine in something the weight of a Subaru would definitely be my cup of tea.

If we are talking Power Engineering/Well Lane/AP22 type figures then it could still probably be done at 1.3 bar from the looks of it. Whether this will be a geunine 450 BHP matters less than it being at least as quick as it is now but with some reliability.

I took the car out yesterday and never went full throttle except in 5th gear, that is how worried I am about the Subaru gearbox, but it was still an absolute hoot to drive....although I have another gearbox on the way.

So I need to focus for now on what if anything to do in terms of liners or closing the block to reach my stated aims. More thoughts on this appreciated.

Pavlo

yhm (well soon anyway)

Andy.F

Paul

See link, this lot had problems with the crank tunnel going out of line after the welding. Is there any way you can check this ?

http://www.pms.net.au/performance.htm

Andy

Pavlo

well that's what they say! but how much of that is to put you off doing it yourself?

easy to check with round insert and plastigauge

Paul

john banks

If I got 90% VE at 6500 RPM, then 640 CFM at 1.5 bar may result, which divided by 1.42 is 450 BHP

Mark you previously said 85% VE might be conservative... maybe I am in with a chance. This point looks sensible on the compressor map too. But with no head work??

john banks

I printed off the 16G compressor map and the 20G compressor map. The latter I squashed down by 20% horizontally and then traced in red where the surge line would sit to simulate a 2.5 with 20G compared with a 2.0 with 16G. On the TD05 I find that at 3200-4000 RPM it surges if I run more than 1.2 bar.



Looks like up to about 1.2 bar on the 2.5 it will be similar. So a clip might sort it... of course the 2.5 will also spool up the turbine earlier as well. Need to see how it goes.

[Edited by john banks - 2/23/2003 3:32:51 PM]

Pavlo

you can measure your current VE if you know the mass airflow and ambient temperature.

Paul

NITO

lol@gearboxes!!

I'm trying to locate a six speed STi box for my project, and I really fancy the Suretrac diffs from the STi7/8, should be great fun in a classic scoob.

I'm looking for similar figures to you with complete reliability but I've decided I'll be going down the 2.2L route as I want it to rev higher than I'd be comfortable with with a 2.5. (read 8000rpm in top for that theoretical 200mph mark!!)

I'm looking to use a 2.0 closed deck block probably with the HKS 2.2L stroker kit, a big head stud kit, enlarged Sump, and some decent conrods (which is about the only thing I haven't decided on which ones yet) and run this between 1.7 -2.0 bar. Also looking to use the sti4 set up of sodium filled valves and underbucket shims with HKS cams.

I'm currently going to be running 1.6-1.7 bar on my std bottom end bar metal head gaskets all in the name of research. Don't think that P1 box will last long though!

NIto

David_Wallis

I thought 8000 rpm through the sti box works out at 175mph???

Guess what box and what rev limit I have?

David

NITO

lol 200mph??

The STi 7 Type UK has the same sixth as a uk fifth. ie 100mph = 4,000 rpm 100/4000=0.025 x 8000=200mph give or take a few variables..hmmm wonder what effect aerodynamics would have and if this is indeed realistically achievable!!

ustolemyname??stevieturbo

iTrader: (1)

Where did you get the ratios from, and are the UK and Jap spec STI7 boxes different???
Info I have state that the 6th gear in the STI7 box has the same overall ratio as 5th in a P1, which would give approx 175mph@8000rpm. Allowing for the different diff ratios.

6 Speed ( Jap spec )
3.636 (1st),
2.375 (2nd),
1.761 (3rd),
1.346 (4th),
1.062 (5th),
0.842 (6th),
3.545 (R),
3.900 (final)

Using Gear ratio calc
215/45x17 Have a rollout of 192.3cm

After a quick search, it would appear the Jap box has different ratios from the UK.
UK 6 speed
GEAR RATIOS: 1st 3.636
GEAR RATIOS: 2nd 2.375
GEAR RATIOS: 3rd 1.761
GEAR RATIOS: 4th 1.346
GEAR RATIOS: 5th 0.971
GEAR RATIOS: 6th 0.756
GEAR RATIOS: Reverse 3.545
FINAL REDUCTION GEAR RATIO 3.900

Potential top speed 194mph @ 8000rpm


[Edited by ustolemyname??stevieturbo - 2/24/2003 5:31:42 PM]

NITO

The P1 is lower geared than a std uk car. 100mph in a P1 in top is around 4,400 rpm as opposed to 4,000rpm in the uk car. An STi 7 Type UK has the same sixth as a std UK car 5th. The STi7 jap spec is lower geared than the uk Sti as far as I know.

HTH

Rgds
Nito

ustolemyname??stevieturbo

iTrader: (1)

6speed pics and info
A couple of pics

john banks

Boostaholic Banks would better suit a 2.33 closed deck block, so that is the current plan.

Will still try to use the JECS, TD05/06 20G, standard heads and the same power targets, but the stronger bottom end would allow a little more later if needed.

A large influence in this decision is the need for custom rods for the 2.4 liners, and the fact that it would still be open deck. Block closing techniques in the UK are still experimental. Open deck block reliability at high boost has not been proven although Harvey's car has done well. In addition the CDB has oil spray.

In addition, the cheapo option of using off the shelf JE pistons/Eagle rods leaves a difficulty that the pistons would probably end up custom to get the dishes to accommodate my turbo heads.

dowser

John,

Why not fit oil squirters? I (or, my builder) plan this on my ej25 build. Mine will stay at 2.5 with aftermarket pistons/rods/studs/oil pump.

I'm not speculating on power to be obtained - but I'll be p*ssed if it's less than now Hopefully around 400ps, with as much torque as I can until charge temps get excessive.

I'll be limited by keeping a tmic (at least initially ) - I'll experiment with the 06 compressor, but will also test a smaller Audi KKK alternative.

I'm also getting throttle opened out for 13% more flow and having the manifold flow-matched per tract (no idea if this will make any *real* difference - but logic suggests it must). Not sure about head work yet - probably just port match inlet and exhaust, it will be up to my engine builder.

Oh, and a 4th header design to try

Richard

Pavlo

I'm still failing to see the requirement for custom rods for the liners.

It would seem that the customs rods are required because the pistons are not optimised for the application with the correct pin height. Ron said this was because of ring langs, so why not move the ring positions. Afterall the long rod is what the EJ25 uses as stock.

Still, at least you have the crank now.

But correct me if I'm wrong, you're still going to have to spend loads on liners for the closed deck block? I know you're trying to do this on a budget, as are all of us, but you seem to be loosing the plot. Maybe you've found it again I don't know, or maybe you've been listening to to many other people that have swayed your opinion on going down the good driveable power route.

Paul

T-uk

paul,

Boostaholic Banks really has no will power, he needs the added safety net of the closed deck block.

the other good thing is that if the CDB is taken away from my place,the temptation to do something with it myself is removed

john banks

The point is Paul that it is not a simple bolt together kit unless you have a Phase II EJ25.

I am notorious for going further than I ever planned. The apparent cheapness of off the shelf parts may be deceptive when you consider the effort to finally get exactly the right bits in your hands that all fit together.

Pavlo

I know the problem, I started with a Sti5 engine with std internals!

I think you have to plan towards the ultimate goal though. Save on things like cams and head work that can be added later.

Paul

Claudius

Could someone give us a URL to the Eagle rods specifications?

The Pauter or whatever looked good; what about the Eagles?

So 2.4 or 2.5? I think "there's no replacement for displacement" so I say stroke it Seriously, the more capacity, the less boost required to flow the same amount of air (if your head flows enough). TD06 20G looks good, should be good for 500 bhp with 2.5 litres. What about the gearbox though?

Oh, and dont give me that crap about running only 1.3 bars! LOL!

Claudius

Oh, just read your initial post again: arent 550 cc/min ijectors too small?!