sonic93

iTrader: (16)

my mate just went out in a friends evo 8 mapped to 410 with evo 9 turbo he was saying it doesn t hit full boost till like 5k lol it cant be that laggy can it and b mapped well can it lol?

rob

john banks

My Evo 9 used to make 1.8 bar at 2500 RPM IIRC.

Adam-M

As far as i know the Evo 4 and onwards has a twin scroll so either its been changed to a large single scroll like the FQ400 or somethings up.

sonic93

iTrader: (16)

It's 8 with a evo 9 turbo so don't no if there was diff turbos on that model. 1.8 by .2.5 Jesus that's quick spooling

john banks

That was in top gear, flooring it low down, it would reach 1.0 bar at 2200 RPM. If you left foot braked in top gear it would do it even lower but had compressor surge. In a lower gear if you stabbed the throttle at 3000 RPM there was no obvious lag. It spooled like a 20G on a 2.5 litre Scooby engine with similar power. The Scooby was single scroll and didn't have variable valve timing, and the exhaust manifold is of course much longer.

TonyBurns

iTrader: (3)

Maybe the 7 onwards, the 4, 5 & 6 were definately single scroll on the evo's

Tony

john banks

Evo 4 onwards was twin scroll. Evo 1,2 and 3 were single scroll. For Evo 4 onwards they turned the engine round and they have a reverse spin turbo.

Adam-M

Aye a was told the turbos spun anticlockwise, dunno why to be honest as you'd think it'd help loosen any bolts, unless they are reversed aswell.

The Mivec on the 9 is supposed to help turbo spool quite alot.

Adam-M

What is the AVCS then mate, is that for the Cams then? I though the newage STI's had variable valve timing.

So a twin scroll on an Evo with variable valve timing spools just as quick as a 2.5 STI with an uprated turbo? Interesting.

john banks

My Subaru 2.5 was a transplant into a MY00 UK Turbo. I used STI 5 heads.

So the comparison was fixed valve timed 2.5 single scroll TD05H-20G with variable valve timed 2.0 twin scroll TD05HR-16G. Similar peak power, similar response, similar spool up.

Twin scroll, short manifold and MIVEC on the Evo is therefore worth about half a litre of Subaru displacement.

Apart from the slightly different compressor cover, the 8MR turbo is the same as the 9. Comparing these (my friend has one that I mapped whilst I had my 9), the peak power was only about 10 BHP higher on the 9, reputedly due to that compressor cover, MIVEC is neutral for peak power as the cams are swung back again, there were a few changes to cylinder head coolant jacket that gave the 9 a little more knock resistance. But the main comparison for spool up between these similarly modified and mapped 8MR and 9 was the MIVEC. It was worth about 300-400 RPM in terms of spool.

The 2.0 twin scroll AVCS Subarus spool well as Tony will tell you (he had/has a Spec C). Pretty much like the Evo in terms of power band, but the ultimate power potential of the turbo was 10% short. Perhaps the longer manifold and TMIC on the Subaru hold it back slightly.

IMHO, for a road car with sensible gearing and rev limit in the 7500-8000 range, you really want pretty instant response at 3000 RPM. Otherwise you find you're on the motorway and have to drop a gear to get meaningful acceleration, or you have a buzzy cruise. A 335d will utterly destroy you otherwise!