what aftermarket turbo's are available for the 20vt and what power levels/boost are they good for? e.g. gt28r/rs ect ect ect just doing some research

standard but with 360 bearing for a bit longer life,
GtiR and Superspool are rated to go above 300bhp i think someone has hit 320bhp with one but that was a fair bit of other bits done as well.
Then your into Roller Bearing territory
Here we have GT28R for upto about 350bhp but some have got a bit more.
GT28rs(i have one) they are rated upto 380 i think, and more if you go for the larger .86 housing and not the .64 housing i got
Barbz does whats called an RSR, the best bits of the GT28R and the GT28RS for a better spool up.

Then its GT30 territory....
Price depends on where you shop and how tight you are

so who sells um

Torque Italia does the lot IIRC

Cheaper prices if you want to source the bits yourself mind but barbz only does good work to coupes

whats the powerband like on the rs king???
im basically after 300bhp+ but want something that aint too laggy for everyday use and i dont want an on/off switch.think maybe about 350bhp may for me although im gonna be running nitrous so tbh 30bhp will probably be enough.
will pay whatever for the right bit of kit and i know a decent rb turbo is about £1k which aint too bad.am just drawing a spec up at the moment

The RS won't be that laggy with the .64 housing beast. The 28R sounds good for you, good for about 350BHP and nice quick spoolup!

You running standard internals KP?

well inital spec im looking at is:

fmic and piping
uprated rad
straight induction and cone filter
some form of cold air feed
turbo for 300/350bhp
16vt injectors
unichip
uprated pump and 3.8 bar reg
colder plugs
uprated pistons and rod bolts
maybe lightening the crank and rods but not sure yet
lightened flywheel
unichip
uprated clutch

think that should be good for 300bhp+

oh and a nitrous kit for the drag strip and messing about with hence the pistons

i dotn want an animal but would like to get in to the 12's for the 1/4 mile

So which is better, the GT28R or GT28RS and what are the differences in everyday driving?

Youd maybe be ok without the unichip and just a good setup at PT instead fella.

I run stock internals on my coupe but im at about .6bar max .8bar on my rs turbo and its not too laggy, it doesnt pickup as quick as my dads 2.1 does low down but once she gets above 2.5k revs she gets up enough for me the rs is meant to be better turbo than the r but id say go rs if your planning nitrous so that it doesnt hinder the air being pushed out as much. Water wetter would be a better use of your money than an uprated rad and aquamist can always help. Sorting out the oil vapour system is a good idea as well and a cold air feed isnt really needed for the SI pipe and a cone filter. Buy JohnS's airfilter asap if u want a straight induction pipe though!

RS is laggier than stnd turbo. 0.64 or 0.86.

Thats the way to look at the turbos now. How do they compare to stnd turbo.

If you want everyday driving beast go for the gt28r. It will cope with what your going to throw at it and it will allow daily driving.

Ross

can you get a custom mappet chip at pf then??was thinking i would need a univhip to run either the 16vt injectors or the 440cc injectors barbz sells as im looking at making the fuel system good for 350bhp plus 100bhp of nitrous just to make sure.i would rather have an uprated rad as a precautionary measure
yeah will uprate the oil breather system.still not sure about headwork or cams yet-whats the limit of the std head and what benefit do stage one cams have?
the rs sounds ok if it pulls well from 3k it will be ok for me

It doesnt pull well from 3k. I've yet to see an rs graph that shows the claims that people make. They say i see "1 bar boost from this and that". With barbz headwork, a good exhaust and downpipe, straight induction pipe and a gt28r, im getting better spool up than a superspool and a GTiR. Getting a kick in the back at 2700-2800rpm.

Dont get the RS if you want it kicking in at 3k.

Ross

Or the 28R. Mine may well have 1+ bar boost at 3k, but nothing actually happens until smack-on 3.5k.

My 28R used to give 1 bar by 3,000rpm, but it wasn't pulling hard until 3,300

My GT2871R also gives 1 bar by 3,000rpm, but this is probably due to the flowed head and straight induction pipe helping out by two or three hundred rpm.

Its on song by 3,500 and only drops a bit by the redline.

If you want 300bhp and not much more (other than by nitrous), I would suggest looking at Highwayman's setup - Perfect Touch were very impressed by the way it drove - very early spoolup, massive midrange and tailing off gently to the redline. Its probably a monster car on the road - quicker than mine in most situations.

you mean using GTiR Turbo + some bits to reach that

I posted this somewhere on the forum before -
roughly it goes -

plain bearing CHRA
T28 Superspool hybrid max made 313BHP
T28 Std turbo max made 288BHP
T28 hybrid max made 300BHP
T28 GTiR hybrid max made 320BHP

Ball bearing CHRA
GT28 0.64 (no one using this)
GT28R 0.64 max made 344BHP
GT28RS/R hybrid 0.64 max made 378BHP
GT2860RS 0.64 max made 350BHP
GT28RS/R hybrid 0.86 (no one is using this)
GT28/32 hybrid 0.64 max made 350BHP
GT30/25 hybrid 0.64 max mad e370BHP
GT2860RS 0.86 max made390BHP
GT2871R 0.64 max made 400BHP
GT3071R 0.64 max made 380BHP
GT2871R 0.86 max made 480BHP
GT3076R 0.64 max made 460BHP
GT3071R 0.86 (no one using this turbo)
GT3076R 0.86 max made 500BHP
GT30/35 hybrid 0.86 max made 440BHP

That's about all the turbos you can commonly get from Garrett including the hybrids. I have put them in order of spoolup not power. The power figures are what I can remember...
These are all for internally gated turbos

JohnS - great post - its clear that the turbine housing makes as much difference as the choice of turbo itself. For example, the GT2871R 0.64 makes the same if not a little more power than the GT28RS 0.86 - however, spoolup will be better on the 2871

One point though - GT2871R 0.64 - max power is probably mine, now running over 400bhp

The only problem is that its impossible to compare directly, as very few owners have got exactly the same sub-set of modifications. For example, a big turbo with a stock downpipe may give worse results than a small turbo with a bigger downpipe.

It all goes to show that its the compatibility of the mods that makes big power.

The turbine housing affects not just the absolute power and efficiency but it affects where peak power is delivered in the rev range. When sizing a turbo ideally the power should be just starting to tail off at your rev limiter (wherever you choose to set your rev limit at). So the choice for arguments sake between the GT28RS 0.86 and the GT2871R 0.64 is one around matching the engine modifications to the correct turbo to achieve the full power band within the rev range. Also of course the delivery of power is different per turbo in terms of lag and turbo response.

AFAIK the GT2871R 0.64 spools up later than the GT2860RS 0.86 but can make more power.

There are other turbos not in the list like the GT3082R or the GT2876R neither of which have much popularity at the moment.

yeah great post johns and shows me just what i want to see.
how much of a difference does headwork make to spoolup i.e. general porting and 3 angle seats as i aint really interested in bigger valves.also what effect do cams have?i notice a number of people are now using c&b cams whereas when i was on the forum a year or so agao most people werent bothering with cams

The headwork makes a big difference on my setup and all of the high-power UK coupes (380BHP+) have one of three designs of headwork. The designs are
Stage 2 - 3 angle head/backcut valves + porting and change to alternate valve guide design
Stage 3 - Adds oversized inlet valves
Stage 4 - Adds oversized exhaust valves + valveseats

(with stage 1 being a basic 3 angle head)

On my setup (stage 4 head) its made several hundred rpm improvement on spoolup and flows more at the top end.

It's fair to say though that Barbz who has supplied these heads has got to his design through a lot of effort and none of the headwork done elsewhere has had the same effect.

The C&B cams are probably a nice-to-have to be honest - they do improve the overall power delivery but bang per buck they are quite an expensive modification. I was the first to fit the C&B cams in the UK and so I did do a back-to-back comparison - they improved my spoolup, but because my turbo was already at its flow limit they made only a few BHP difference at the top-end.

I'm pretty sure I can squeeze a bit more power from the GT28R 0.64 - I'm not running CAMS or Aquamist + methanol. The map I have is also on the conservative side at 11.9 AFR. Sheiks runs the same power but unmapped (with Mist + cams though I think) so I reckon with good mapping he could go over 350 also.

It's interesting that I am still building power going into a 7000 rpm limit, so I make peak power at the same point as Nigel who is on a bigger turbo - any comment John?

I think you should run a 7300rpm limiter

whats the standard crank good for john?balanced and unbalanced.

probably good for more than you'll ever need to worry about. std crank is usually reasonably well balanced so good for around 700BHP+ I would guess, plus more if it were balanced. The balancing issues are typically the pistons and rods.

you have PM...

John,
does that mean we shouldn't bother with balancing the crankshaft? I'm not planning to more than 7.200rpm (since I'll probably wont be running 3ple springs as Rich and Begbie and I assume others do...

cheers

well i know from when i took my old engine apart that the crank looked a hefty piece of kit.what mods to a std crank would you do?just lightening and balancing,just lightening,knifedging?like i say im only after 300bhp,maybe 350bhp but im gonna be using nitrous so i want an engine capable of withstanding 400bhp just as a precaution

Suba i think sheik was only running cams, no mist.

I'm going to try and get a better bhp figure from my car than when it was running rich. Hopefully with all the info im learning about the car through the wideband lambda sensor, i can put it to good use.

Ross

Vas, I don't know about the 16VT cranks - sorry!

@Beast - I would just leave it as-is for 400BHP. Flea is running an unbalanced crank. Save your money for forged pistons and rods if you want to run 400BHP without losing a rod, piston land or both - esp with nitrous where it is backed up by equal/more torque