Mr Footlong

iTrader: (7)

Hey folks. My new turbo will be coming from Andy F at the end of the month once I give him the cash and we settled on a 20g as the replacement for my VF28. Being a bloke I told him that I wanted as much power as poss while still being mildly sensible. Not being fussy I also would like great punch from 3500 rpm onwards (use this a lot for motorway overtaking and would like to not have to drop to 4th as much ). Now I could ask Andy all this but I have spammed him enough for one week I think and was wondering if the ones amongst us with knowledge in this area could give me their opinions?

Basically what difference in performance/power delivery across the rev band is there between a VF28 and a Andy F TD05-20g? Whether I buy the 18g from him or the 20g they cost the same so he has no vested interest in selling me one or the other .

Cheers,

Nick .

Mr Footlong

iTrader: (7)

Back to page 1 .

Henrik

iTrader: (5)

We've got a WRX, so maybe not completely comparable, with a AFP5-20G.

Compared to the standard TD04, the car is rather dead under 3k to be honest but nice kick at 3500 RPM onwards, though. Pootling around town is a bit of a pain, as the car needs to be revved all the time to move, but when you're "going for it" it's fantastic

I don't know if me and my wife being crap at driving, but pulling off fast in first is really hard. With the TD04 getting near perfect starts every time was not a problem, but so far we haven't managed to start quickly once with the 20G. Only tried about 3 times, but still

First gear is completely useless as it's over too fast and it doesn't have time to hit peak boost in 1st either. 2nd gear is slightly better, although that's over in about two something seconds as well (still not hitting peak boost i think). In third the car flies, but then you're already doing 80.

It's a great turbo for hooning about, but I wish I had some more low down torque. Then again, it probably makes almost as much power lower down as it did earlier, but it's just that the top end is so much better now that it feels comparably rubbish, if you see what I mean. The wife, who to be fair drives it more than me anyway, doesn't mind.

Mods include:

* AFP5-20G
* Lateral 3 bolt headers and up-pipe
* PPP sports cat
* decat centre
* resonated centre
* PPP backbox
* Autobahn FMIC
* apexi power induction kit
* walbro 255
* Ecutek remap


Here's a power / torque graph: http://www.bilar.co.uk/subaru/graphs

Mr Footlong

iTrader: (7)

Thanks for your detailed take on your setup Henrik .

Ooh look, that gets a bump

I am still sorely tempted to change my Hyperflow TMIC to a FMIC but I think that the change to that and the 18/20 will seem like lag city. Hmm, don't want much, great midrange punch and doesn't run out of puff along with instant response.......

Mr Footlong

iTrader: (7)

Hmm, just looking at your graph is very informative, serious top end turbo.

harvey

iTrader: (48)

I have a VF 28 spooling to 1 bar in 4th at 3,150 rpm. It typically runs at 1.3 bar dropping to 1.2bar. My own TD05-o6 20G(if that is what you are comparing) by comparisson, will hit 1 bar at 3350 rpm. The VF 28, a roller bearing turbo is a bit more responsive low down. The TD05-06 20 G is sleve bearing and runs to 1.7 bar max and will probably run a bit more but there is no point. Incidentally it is running 422 bhp which is a high figure for an o5-06 20g. Typical 05-06 20G that I have seen on the rollers will make around 385 bhp which in similar circumstances is 50-60 bhp ahead of the VF28 on similar mods.

Mr Footlong

iTrader: (7)

Thanks Harvey.

Ok, heres a brainless question, but one that might just make my decision for me.

Just for example (of course ). Sitting at approx 70-80mph in fifth, behind a queue of cars not going in to the completely empty slow lane for no good reason, all being held up by a Saab, BMW or Audi . Suddenly everyone gets out of my way and I put my foot to the floor, staying in fifth. In general, which turbo is going to pass the traffic more quickly, the 18 or the 20?. If I dropped to 4th instead would the results be the same?

Silly question I know, but had to at least put it down and see what folks say .

harvey

iTrader: (48)

So the leading question is, what revs do you see in 5th at 70-80mph and what are the revs in4th at that speed? Let me know and I will give you my experience.
Different models= different diffs and gear ratios coupled with different tyre combinations so there can be very signifigant differences in response.

Mr Footlong

iTrader: (7)

I won't be driving for a couple of days but if memory serves the speedo shows 90 at 4000 in 5th (speedo reads a bit high compared to GPS so prob low 80's to mid 80's tops). Just an educated guess would be useful to be honest

Henrik

iTrader: (5)

I would think that from that rev onwards the 20g would have the edge, and the 18g below (but that's just my guess)

harvey

iTrader: (48)

Below, around 3,500 rpm the 05-06 20G needs a gear change if you want the fastest get away. Above 4,000 rpm the 05-06 20G will just walk away. The transition is somewhere between 3500 and 4000 rpm which is why I was interested in your geared speed figures.
The VF28 is very nice to drive around town and on tight roads but the 05-06 20G comes into its own with a vicious surge of power where higher speeds are attained.

GazTheHat

Between the two, the 18g is a better "real-world" turbo. Not the mentioned lag issues. Depends how you drive though, the 20g owners have warned you.

Mr Footlong

iTrader: (7)

Cheers guys, the info is most useful and I will make my final decision shortly .

harvey

iTrader: (48)

Gaz, is that from your experience of driving 18g and 20g turbos.
The step up from a VF28 to an 18g is perhaps not enough to make the change worthwhile in terms of added performance versus cost.

GTscoob

VF28 is a lot like the VF29 I had on my old USDM motor. I'd get 19psi by 3100 revs or so. Its my favorite turbo for a 2.0 as far as all around response, I've driven other cars with VF30s and VF39s but the 29 felt better at any point in the powerband.

rasonline

The VF28 came on the STi 5 and sti 6 models. Later sti 6 models came with the vf29.

vf28 is also very similar to the vf24 (almost exactly the same actually).

On my STi 6 i had the vf28 which was brilliant for driveability. But also consdier gear ratios, as i have shorter gears than the wrx. So 3,500rpm in 1st or 2nd just to get the turbos in their zone wasn't issue.. short-gearing.

I've recently changed over to a Garret T3 T04E turbo.. which i think is bigger than a TD05-20G? But still tuning the car so can't comment on setups yet. Will keep updated.. just to confuse the issue even more

Andy.F

VF 24 (similar to 28) against a 20G on the same car.

This was mapped specifically to protect the UK box, ie regulating the midrange torque output.


Click to enlarge

Mr Footlong

iTrader: (7)

Wow that graph makes it look like there is no real reason not to get the 20G! I had already decided to stick with your judgement on this one but that that clear image is the icing on the cake tbh .

Thanks.

Henrik

iTrader: (5)

Which one of the maps was regulated?

Also, out of interest, have you got a similar graph for a standard uk wrx with a td04 (prior to remap)?