anyone ran a td04 hybrid on a 2.1? What's response like?
 

Does anyone have any experience of a hybrid td04 on a 2.1 (wrx heads)?

I have a Blouch billet td06-20gat the moment, and even thought it's still being run in, and I can feel that it will be a great turbo on the road for my type of driving (I like the nothing-nothing-nothing-BRAAAAAM feeling :)), I think it will be too laggy on track for my liking (then again, I might just be talking rubbish - perhaps it'd be great).

Boost threshold isn't too bad in all fairness - hits 0.7bar at about 3400 RPM in 3rd gear (so actually only very slightly slower than my old AFP td05-20g non billet on a 2.0).

I'm keen to see what kind of response I can get from the engine this time around, so thinking of detuning. I've already gone back to STI TMIC + panel filter, and will take my RCM headers off in favour of ported standard headers.


Here's the thing, I have a td04 with a HL exhaust housing. The HL is not the same housing as the TD04L that came on the UK cars (it's significantly bigger), and I'm thinking this might be a good match to the 19T hybrid wheels (which the TD04L exhaust wheel chokes to < 300hp).

I don't know if anyone else has really ran the 19T wheel on a td04HL, so really looking for opinions.

I'm basically after near instant response and low lag.

Also I'm thinking that 330hp or thereabouts would be plenty. I don't want to sacrifice a lot of lag time for increased HP.

I'm also getting old and coming to the conclusion that more power isn't always more fun... it appears to mainly mean significantly more money in terms of running costs, especially on track days.

TD04L = 41.3mm exducer, 47.0mm inducer
TD04HL = 45.6mm exducer, 52.0mm inducer
VF34/5 = 48mm exducer, 53.2mm inducer

13T = 56mm
19T = 58mm
VF34/5 = 60mm

So a TD04HL 19T is slightly smaller than a V34/35 - either should give you your desired results.

I thought that the point of the 2.1 increase was to allow a bigger turbo to spool up quicker?

Thanks technoplug :)

I suspect that possible power output is more or less linear to the area of the exducer/inducer (give or take a little bit). I don't have any proof of this yet, so it might be completely wrong.

If it is proportional, then it looks as if a td04HL might flow to about 340hp (if the compressor can supply enough air, of course), so it looks almost perfectly matched to my goals. This is assuming that the td04h is only good for a maximum of 300hp (usually, I think I've seen up to 315 somewhere but those are probably in the minority).

Is the td04hl what you speak of the same as the turbo on jdm legacy twinscrolls?
If so there is someone on uklegacy.com that has 330bhp from theres.

Great info, stamina_daddy!

I think the legacy turbo is a TD04 HLA, which is a twin scroll "more or less equivalent" (maybe - similarish size wheels at least), so maybe that points to what is possible.

The legacy is a 19t from the factory, so probably similar output achievable with the 19t billet wheel (maybe a tiny bit more).


Hmm, now the question is, can I live with 330hp, or will I feel disappointed down the straights?

I know that slow corners where I could either sit at 4000 RPM in second, or 3000 RPM in third were a real problem with the old setup (td05-20g non-billet on a 2.0). For example, druids at Brands, and the bendy bits at Cadwell. Literally 1s+ lag in 3rd, or run out of gearing immediately and have to change.

The mid way point would be something like a td05-16g billet... I have a td05 in need of a rebuild sat on the shelf too, hmm...

here's an interesting thread from 13 years ago: https://www.scoobynet.com/general-te...brid-td04.html

I have a wr limited legacy myself.
It's been remapped but from what previous owner said only to to 300bhp as he was worried it would blow up.
It's still got standard downpipe as well.
I'm only in sydenham London if you wanted a go out in it.
If you remember I'm chops friend justin.
Saw you at track day when you had Mitsubishi.

We sell a stage 2 hybrid TD04 that makes 345bhp on stock 2 litre engines with good spool.

What building process makes them a stage 2

Ah yes, of course! With the blob wagon :) he did mention that you had got rid of the wagon and got yourself another Subaru.

I will take you up on your offer, however at the moment I've got exam and project period at university. I will drop you a pm sometime in June when exams finish (no idea why I went back to uni - there's probably something wrong with me).

How would you say this compares to say a billet td05-16g (ie something like the sc36)?

I don't know if you remember, but there was a chap called Malc who had a bug eye wagon with an sc36 and a 2.1 done by yourselves. At the time that I bought it, I didn't appreciate quite how nice the torque would have been on track, so unfortunately got rid of the turbo.

I have a TD04 HLA 19T Twinscroll which is standard on the Spec B GT Gen 4 Legacy. It is a bit of a hoot to be honest. Whilst the Legacy is not as dynamic as the Impreza the turbo helps it shift along very nicely, being a TS it picks up early @2500 rpm and just keeps going to the mid 7's. After a remap 319bhp with just a Cosworth filter was easy. It sounds quite interesting with an HKS Sport cat and twin Nur Spec (not R) back boxes :thumb:

That flanges etc are unique to the Legacy and there is no swap over to the Impreza as a warning.

Edited - just saw Justin's reply.

That is great information, thanks!

I have a single scroll TD04HL turbine (and housing), so I'd expect to get similar top end figures but at a slightly later rpm :)

I think I will have to do it...

Mine! :D