Fitting higher flowing Garrett turbos - what's involved

[Caveman]

Guys,

As you know my car has gone as far as it can on the stock turbos, so like many I've decided that bigger turbos is the next logical step.

I understand that TD04s are the cheapest route, but the amount of relocation and general faffing around required really puts me off.

What I'm looking to do is find turbos that will give me a safe 400-450 bhp, whilst only requiring adapter plates, downpipe modification and revised plumbing. Some people have mentioned the GT2554R as a good bet, but the rated power is way more than I need and they do still look quite a bit bigger than the std TD03, so I'm concerned about clearance isues. I was wondering if the GT1548 would be a better bet?

Ultimately I want to know if there are any turbos that will fit and offer good power without requiring relocation or removal of stuff. I've heard of aircon units being removed, thinner radiator fans and all measure of messing about to get turbos in.

Does anyone know what will fit with minimal messing around?

Answers on a postcard!

Cheers,

Mart.

[Kieran]

Unfortunately, the "Easiest" option is TD04s. It's not really as simple as you'd like it to be. TBH I don't think it'll be too long before the TD04 route is 'Cracked' and it's offered as a kit... It's been done now and I know several others are looking at doing it.

Looking at the compressor maps, I doubt the GT15 series flows enough anyway.

Search around for posts by Valmes - One's called 'Let's think bigger turbos' as I recall, lots of info in there.

[Caveman]

Hi Kieran,

thanks for your reply. I thought the TD04 route required relocation of things such as the aircon pump, smaller radiator fans and bulkhead hammering?

Are you saying TD04s will fit with just adapter plates, plumbing and modded downpipes?

Cheers,

Mart.

[Nutter_John]

There are different TD04's , the ones K reffer's to are from a scooby

[Nick Mann]

I am working on a kit. It is no-where near ready yet, so if you are in a rush, don't wait! I am hoping to have costs ready by spring, with the kit being available soon after.

I will obviously let everyone know when I have some news!

[djb160]

what sort of kit is it Nick? Is there a link to a thread for it somewhere?

[Nick Mann]

It doesn't exist yet, but it will include the minimum amount of stuff to fit a pair of subaru WRX turbos.

Taking an abstract guess it will include:
2 exhaust elbows.
A few nuts & bolts.
A few lengths of hose.
A few Samco style couplers.
A few Banjo bolt fittings.
A thinner radiator fan.
An oil filter relocation kit.
A couple of actuator brackets.

The turbos will need clocking and the exhaust manifold flange on the turbo will need drilling ant tapping.

I can't guarantee that any of this is spot on yet, or that any other issues will be found on the way, so like I said - if you are in a hurry then don't wait!

[Caveman]

Hi Nick,

Thanks for the tip.

I have been looking further into similarly sized turbos and I still think the Garrett GT1548 could be a good bet. It's both oil and water cooled and flows up to 200bhp in standard trim. A bit of hybridising can easily get it to 250bhp or more.

The real beauty is that the GT15 is the same size nearly to the TD03 so it will require the most minimal mods to fit.

Here's a comparison pic between our TD03 and the GT15:





Cheers,

Mart.

[Nick Mann]

Sorry to be a pain, but neither of those turbos is a standard VR4 fitment. The VR4 uses a TD03, not a TC.

Having said that, I am still wishing you luck with your project - I guess we could help each other out whilst we are both looking at similar stuff!

[Kieran]

I have been looking further into similarly sized turbos and I still think the Garrett GT1548 could be a good bet. It's both oil and water cooled and flows up to 200bhp in standard trim. A bit of hybridising can easily get it to 250bhp or more.

To say a turbo will 'Flow' a certain amount of BHP is a risky business. It really depends on what engine it's on.

If you look at the compressor map here:

http://www.turbobygarrett.com/turbob...5_3_comp_e.gif

You can see that the GT1548 flows 15lb/min at a Pressure Ratio of two (Effectively 1 bar of boost). Now whilst on the Garret GT1548 map doesn't show the air density or temperature, in the past Garret maps have been based on a temperature and air pressure that one would see in real life. Rather than reproduce a lot of info, have a read of this:

http://www.stealth316.com/2-3s-compflowmaps.htm

The paragraph beneath the very first compressor map shows what garrett have used in the past and how to convert lb/min into CFM. For the purposes of conversion, I think it is a reasonably safe assumption to use the same calculation (10lb/min = 144.7178CFM).

So, at 1 bar boost, the GT15 is flowing 15lb/min and it's in the 70% efficiency zone - not too bad but you wouldn't want to get much worse than that. 15lbs/min = 217.0 CFM x 2 = 434CFM.

Somewhere on here, someone worked out the CFM requirements for our engines and as I recall the flow rate was something like 450ish in standard form at 0.9bar - So I still say you need to be thinking bigger.

[SGHOM]

basically Mart...... If you want to go faster in a VR4....... then buy a skyline.

[scientist]

basically Mart...... If you want to go faster in a VR4....... then buy a skyline.

Wheres the fun in that? Its because hardly anybody is taking the plunge why parts are so scarce for these cars. Stick with the MHI variants, they will not fail you or be as problematic. Atleast u can rebuild them when they fail unlike the GT series ball bearing turbos.

So far its been proven that twin TD04s from the subarus are very compatible bolt ons with very minimal modifications. That in it own opens up a lot of options for WRX compatible turbos, since there are many bolt on turbo options for the WRX.

[Turbo_Steve]

I'm in the MHI camp too: whilst they may not be as good turbos as Garrett GT series, they are damn good turbos, and represent excellent value for money. More importantly, they are incredibly easy to hybridise...again for very little expenditure. A properly specced GT is going to have equivalent spool and more eventual power than an MHI unit, and cost more. Whilst that is brilliant for those of us who want uber-huge power and normal driveability, it would appear we're not there yet: TD04s and TD05s seem to be able to deliver enough power to damage drivetrain and possibly engine components, whilst spooling early enough to remain civilised. A TD05 turbine is probably about on the limit, I would suggest, but there may be margins in the map for more.
A pair of TD05-16Gs should just see you into 600bhp territory.

[Caveman]

Hi Nick,

Thanks for your comments, collaboration would indeed be worthwhile. I do have to correct you on the turbo designation though, the VR4 definitely has a pair of TD03-07G turbos, not TD03s. If you look back through past threads from Valmes etc, they have had them out and rebuilt and have recorded the model numbers. The ones in the fotos are the same as ours!

Kieran, if you look at the foto of the GT15 you can see that both the thickness of the turbo wheel area and the outlet are much larger, whilst maintaining similar overall dimensions, surely this should allow for greater flow compared with ours??

As for comments on Skylines over Legnums, they're two different cars. I always wanted a fast , 4WD, good handling, yet roomy estate and the only other car in this league would be the RS4/6 or Legact STI, none of which I can afford. So Leggie it is!

Mart.

[Nick Mann]

I do have to correct you on the turbo designation though, the VR4 definitely has a pair of TC03-06A turbos, not TD03s. If you look back through past threads from Valmes etc, they have had them out and rebuilt and have recorded the model numbers. The ones in the fotos are the same as ours!

All good collaborations should start with a row!

I'll bet you whatever you want that neither of the turbos from your photo is from a standard 8th gen VR4. I am 100% sure that neither is the correct fitment. The one on the left appears to have an extra hole in it (some sort of external wastegate thing?) and the one on the right has a square exhaust manifold flange. Both incorrect for our cars.

I'll do some double checking on the model number, but I'm 95% sure I'm right.

[Caveman]

Hi Nick, the ones in the fotos are TC03s, but not the exact same version as ours, but still the same size, just different fittings. I'm sure we have TD03, happy to be proven wrong though!

Mart.

[Nick Mann]

Looking closer at the TC03 above, the compressor and turbine housings are wrong and the actuator is different. I'll see if I can get any numbers off the turbos in my garage tomorrow.

[mpau009]

Yes, the turbos are definately TD-03's, i have mine i a box, and the numbers confirm the info on the list attached. They come with the 7g compressor wheel, and it is steel not ceramic as some people on OZVR4 thought for a while.

[Caveman]

I stand corrected!

Cheers,

Mart.

[Gowf]

Yep definately TD03, i have 04's from a gto. They have almost the same flange as the 03's, but its orientated differently. I am fairly confident that you can get the tdo4hl's on the stock manifold with some modification, but what i found was that the oil filter was a huge problem and required a sandwich plate. Not too much of an issue, but even the sandwich plate was too large. Im talking td05's now, but in the end the original filer housing was cut down, and tapped for some s/s braid pipe to go off to a filter relocation kit.
At the end of the day there is no cheap option available, you cant just bolton, if you do manage to provide a cost effective kit Nick, my hat is off to you.

Or caveman, you could just buy mine!