So guys I’ve got my99 UK Impreza classic. And I want to replace the turbo with a td05-20g. I’ve currently got a vf28 in there but I think it’s time to have some more power. I’m not going to get it mapped for it it to blow up my engine but I’d rather have a turbo which I can up the boost up in due time of modifying internals etc. My question is. Will it straight swap and replace the vf28? Or will I have to make some modifications? If so what would the mods have to be?

 

It will bolt in. IIRC You may need to trim the back end of the block, depending on which compressor housing is fitted.

A 20g will quite likely kill your gearbox unless you're running PPG, samsonas or the likes or 6 speed

 

wait for it, wait for it,,,,,, still waiting,,,,,,,,,,, and it spools

will be a lag monster, engine and gearbox will be well above their safe limits if you go anywhere near its capabilitys. Simply put 20g is the wrong turbo for your car in your current setup.

Your current setup is about the limit you want to be going (assuming the 28 is setup properly) and keep reliability. Save your money and enjoy it as is, dont forget its now a 21 year old engine.

Next step is engine rebuild and upgrade to the gearbox.

 

a 20g isn't that laggy... i had 1 bar by about 3300 RPM from memory, but yes, it's not a td04. I thought it felt very much like a md321T in terms of spool/lag, when I had a ride in one of those.

Having said that, I agree, don't waste your money just yet, unless the VF28 is broken

 

Wow faster replies than anticipated! So if 20g td05 isn’t the way at this moment of time due to 5speed and stock engine internals (which were all rebuild back in 2018) what other turbo could I go with to get me to 360ish but still have enough puff to take me 400 because I don’t really want to spend money on a turbo now and then another turbo in the future for when I do go forged and 6spd. I’m at 299hp to the wheels which is quite disappointing hence I’d like the upgrade to the mid high 300’s a safe zone where I know mr 5 speed won’t spin all of his teeth for throwing a hissy fit. Are stock turbo 2000 engines good for about 380?

 

No they are not.

Is there something wrong with your vf28? In good condition with supporting mods and a remap should see 330-340bhp which is near the limit of your engine/box.
Failing that just throw a cheap vf35 on there until you are ready for the rebuild/upgrade

 

Lateral MDX321H would work if aiming for 400 ish. With the right mods it spools well.

 

Nothings wrong with it just want a little bit more power; although it does make a whine at times. but I’ve been told these are known to do so. But other than that it’s a great turbo just when I got it mapped it didn’t see the best side of 300 and I just want a little more (safe) power. It’s got 440cc injectors sti topmount but I’ve got a front mount which I will be putting on soon, full decat exhaust, k&n panel filter, vf28 as mentioned before. Did get it mapped only managed to get 299 on v-power out of her. But that was a fair couple of years ago. Just a little confused on what to do next before rebuilding her fully as she is my daily.

 

Hmm, so I kind of understand where you are coming from.

I ran a td05-20g on a stock engine + gearbox 2003 UK WRX for 25k'ish miles, and nothing broke (including a bunch of track days). The ONLY thing I had changed in the drive line was an Exedy pink box clutch, and lightened OEM flywheel. Power on mine went from 353 up to 390 odd BHP (the 390 was with a dash of E85 in the fuel - it only made 370 on normal petrol).

There is nothing inherently wrong with a td05-20g on a WRX, in my opinion, but it's not what the cool kids nowadays would run, because it's not ball bearing. As I mentioned, the MD321T spooled no faster on another 2.0 car I had a couple of passenger rides in, but the 321 did make about 20bhp more power for similar spool, so that's something to keep in mind.

I did always expect to rebuild my engine or upgrade the gearbox if it failed, but it never did. The same engine went on to run in a bug eye estate, then making 317 bhp on normal super unleaded fuel. Last I heard, it was still working OK.

My only gripe with the 20g was that it made me fall below the spool threshold on some corners on track, but tbh on the road it was great. I bought mine directly from Andy Forrest back in 2007(ish), and I should have never got rid of it, really.


If you are concerned about spool, you could go for a billet td05-16g instead. Especially if you are happy to get your hands dirty, you can build one from a standard td05 turbo for about 150 pounds, including a rebuild kit with 360 degree thrust bearing (depending on condition of the turbine wheel).

I'm sure there are technically better turbos out there, for example the Blouch turbos (sold by scoobyclinic in the UK as "SCxx") are by all accounts great, but they also cost 2000 (or thereabouts).

I still think that if you're on a budget, and feel happy rebuilding turbos (it's not difficult - lots of videos on youtube), it is hard to argue with the value for money proposition of a td05 based turbo.

 

https://www.scoobynet.com/general-te...o-upgrade.html here are some more thoughts on the 20g i had.

 

I have a td-05 20g coming for sale shortly. It's the Arashi 7cm one - cost me roughly £650 including fees last September. Done about 1,000 miles max I'd say but could have been half that to be honest. Was running it on a bug WRX and it was a lot of fun.

Absolutely nothing wrong with it only I upgraded to a precision one to go along withe everything else I'm doing

 

I'd go along with Shrekstas advice. 360hp and 400hp are two different turbos in my book. Then there's your standard internals that might be ok at 360 but are on borrowed time at 400hp.