MY00 UK + TD05-16g (and supporting mods):



Stayed with the 2.0ltr formula myself when faced with piston ring damage and weighing up the 2.0ltr vs 2.5ltr options.

I've even stuck with the rusty TD05-16g and it's been like that for some 4 years as it just seems to work so well. A well setup mid 300s is enough to show its heels to cars of much higher power and specs.

I would have considered the 2.5ltr if going for 450+.

In response to the original question, much will depend on your budget, goals and what you are after.

 

Here is a MY 06 Spec C graph running stock VF36 twin scroll turbo. Only mods are RCM 3" decat exhaust & K & N filter. Fuel used: BP Ultimate with NF Booster. I would be interested to see similar stats for a 2.5 liter engine with basic exhaust mods.

 

Seriously dodgy boost control on show there. When i put the decat on my twin scroll i only did one pull at full throttle just prior to the first flash to check the stock setup had no isues, it felt exactly as that shows, surging up and down to the peak torque point.

Get it remapped, you wont believe the difference, torque will be up around 390lbft and smooth as silk if it's done well.

 

My06 2.5 wrx.

 

How is the new car going John?

Tony

 

could you print the numbers please, i can't see them

 

That says 365BHP @ 6055rpm, 404lbft @ 3455rpm.

Dyno graphs are pretty useless without stating all the modifications to achieve the figures, including the fuel used.

Going very nicely Tony thanks, just the brakes to sort and I'll be happy with it.

 

 

[QUOTE=johnfelstead;8517995]That says 365BHP @ 6055rpm, 404lbft @ 3455rpm.

Dyno graphs are pretty useless without stating all the modifications to achieve the figures, including the fuel used.

TD05-20g, supporting mods, mapped by Andy F, on v-power

 

Your post = epic fail on so many levels.

WRC = 2.0L = regs
JDM = 2.0L = taxation

 

Don't need peak numbers on that one: 200lbft just a shade over 2000rpm and staying above 300lbft at the redline= nice road car

 

Are Japan's road taxation laws similar to ours then? Because I would have argued that the 2 litre is still used for homologation purposes for WRC, not for taxation.

 

[quote=scooby401;8518026]You need to be more specific, supporting mods could be £5 or £2K worth of parts. If you want this thread to be of any use to other people trying to judge what their options are they need the full story. Put the normal retail prices next to the parts/services if you really want it to be an honest apraisal of value/performance.

 

2.0 STI semi closed block
forged pistons
forged rods
Inlet Manifold heat spacers
STI heads
STI-5 Cams
3 port boost solenoid
uprated plugs "8's"
CDF lightened pulley kit
Dump valve delete mod
MD 321T
Hybrid front mount intercooler
Ported OE headers and matching up pipe
H&S decat downpipe
H&S Res centre pipe
H&S jap style angle exit backbox

421bhp 375t

 

The JDM emissions laws aren't as strict as the USA or EU, thats why the 2.5 came about initially, it's easier to make the emissions levels on a larger engine.

The twin scroll engine is a homologation special design for the Production WRC, the ECU has the ability to run MAFless and the inlet plenum has an AIT sensor that isn't used in road trim configuration, it only gets accessed with the Group N mapping. The VF36/37 twin scroll turbo has a perfect match to the airflow a 32mm restrictor can flow, so it is capable of large torque at low/mid range, but isn't a high horsepower setup. The ECU on some of the JDM twin scrolls has the ability to map each gear individually for boost control, so you can pull as much boost in 2nd as you can in 6th, this makes a very tractable road engine that gives a lot of low gear acceleration you might struggle to match with a 2.5 on the stock turbo.

 

Excellent info as always. Would you say I have this ability for individual boost control on my RA-R? I've finally decided to fit a 3 inch system and get it remapped by either JGM or Bob Rawle. It's making 353bhp at the moment on the standard exhaust, albeit with a few mods which are listed in my plus profile. I'm convinced it could have and should have made more power but Powerstation struggled with the SARD injectors and the scaling of the MAF for the APS CAI as they had never seen either before, well that was their excuse anyway.

 

Holy moly thats some lag, I would take my 2.1 stroker and Turbo Technics T38 over that any day.

 

seconded 200lbft @4000rpm thats a very late spool up. Nice once its spooled up and going, but take its time getting there.

 

I dont think you can on that model, i think the hawkeye version doesnt have the option for the megarom. The best thing to do is get the ECU version your car has and ask your chosen mapper the question, it is ECU variant specific.

I would expect you'll see much more torque than you have now with a decat and remap, the RA-R is on VF42 so should give more top end power than the VF36/37 which seem good for about 360BHP. It's the torque that matters on these stock twin scroll engines, short shift it at 5500-6000rpm and it goes very nicely.

 

The MD321T is far more capable of top end than the engine is producing there, so it's probably being held back on purpose until the rest of the package is up to handling more. It's more suited for the 2.5 if you want it to spool early.

Like all these engines, it's the overall package that matters, which is why it's important to list all the mods so you can judge it properly and understand what the user is trying to achieve.

 

Hi John
Yes i found the pads could be a little wooden on those brembo's, are you going to retain the standard calipers or upgrade eventually to some AP 4 pots?

Tony

 

Just a pad and disk change at the moment Tony, the Brembo calipers should be up to the job i intend to put the car to.

 

Does this mean your off to the ring sometime in the summer then John?

Tony

 

Hopefully, should work commitments give me enough time. Best not take this topic OT though.

 

Aye, will get back to giving these 2.5ltr boys some stick

Daz, the 2.5 is lazy, it delivers its power with ease, hence lazily, and in standard form (which is what we were discussing btw) it doesnt rev as high as the 2ltr single or twin scroll cars (the twin scroll is still the better road car over the 2.5ltr, even in lightly modified form )
What we are not talking about here is spending stupid money on getting xxx power out of the engine, 99.9% of people DONT want to take that route, and the 2.5 is the cheapest option if you want to do that, though most people are happy at the 400bhp mark and with twin scroll technology coming on in leaps and bounds (hence you see manufactures like vauxhall, renault and peugeot producing twin scroll cars) its catching on

Tony

 

My point being that why would you pay £4k for a twinscroll engine when the only differences are exhaust and sump related which could be had for alot less than £4k??

I'd put my money on a well specced 2.5 against a similar specced 2.0L any time!!!

 

have another " " on me Tony

 

The USDM sump is a twin scroll sump, which is a bit odd as it uses single scroll headers.

What you list is far from the only differences. The twin scroll heads are different, they breath better, the cams are far more agresive and have higher lift (aprox 10% more) , the MY05 onwards have a nitrided and crossdrilled crank. It's the engine that was developed to win the PWRC so is designed around that requirement.

All the various configs have their benefits, for most people they would be happy with any of the choices, which config you end up with depends on a lot of factors that will determine the route you follow. Which engine works for you depends what your car comes with, what you want to achieve and what budget you have.

The USDM 2.5 bottom end was a cheap option for rebuilds (now the £ is worth less it's less beneficial financially), but it has it's flaws, when matched to 2.0 heads to do it right it needs a bit more work than just bolting the heads on. The issue i always had with going 2.5 on a 2.0 original car was come resale, you are limiting your market, some people wont be able to get insured on an engine size increase, insurance companies tend to not mind too much about power hikes, but they get more concerned about CC increases. Once you start going to 400BHP levels they do have head gasket longevity issues, so if you intend to do high miles a 2.0 would be a better option if it's a fit and forget solution.

I've rebuilt a couple of my 2.0 engines from previous cars, one is up around the 120K miles mark at 310BHP i think now with lots of track miles, build them right, service them properly and get them properly mapped and they last a long time. How much an engine costs depends on where you are starting from, buying an outright engine package is always going to cost a lot of money if you have nothing to start with. You have to compare like with like in terms of what you are replacing. If you already have a twin scroll that just needs a rebuild then it's no more expensive than any other version.

 

It isn't being held back that much in that application John, looking at the boost profile tells you that. Still 1.8 bar at 7000rpm.

 

There are no glass ceilings in the ROM's for the Hawkeye STi John that I have found yet. The MAF limit can easily be raised. At present mine is scaled up to 600 g/sec air and uses most of that. I am surprised that Powerstation couldnt map for the APS CAI or the injectors.. although changing both at the same time would make the job bloody difficult. I would have thought they would change the CAI to adjust the MAF curve then fit the injectors and remap for them so that only one variable is changing at a time.... but who am I to tell them

The UK STi 2006 sump design is also the twin scroll design.