disco potato on an AVO manifold ?

Fatty · Postby **Fatty** » Sat Dec 06, 2008 10:52 am

quick question guys

i'm looking at getting one of these to replace my old t25.

i'm thinking it should be a straight bolt up job to my AVO gear, as in, everything will line up and none of my existing pipework will need modification. i guess the turbo should just be clocked into the correct position and everything will be sweet.

correct? or are there any hidden pitfalls or gremlins i need to know about?

ah, and housing size, i need to choose between .86 or .64. i'm clueless about which to go for, and what the numbers actually mean :oops:

Woo · Postby **Woo** » Sat Dec 06, 2008 11:18 am

Should bolt straight up Fatty .... but
1. There are two different 5 bolt outlet patterns (well 3 if you count the GT3071R) so you will have to make sure your new one matches your dump pipe flange.
2. The inducer is bigger on the potato than on the T25 so you would need an adaptor to suit (often difficult to get the correct sizes/bends)
3. The general rule of thumb is a small AR# will spool early but be strangled at high revs and vice versa. I would always go for the largest housing, but then again I drag race. You really need to get hold of the maps for the different housings and compare the efficencies of them both for the volumetric range (rev range) you want to work in.
4. Remember 10psi on a 25 is about the same as 6-8psi on a 28 so you'll also need more fuel for the same boost.
5. Hold on to your hat, we're going ballistic

Bazz

Postby **mx52nv** » Sat Dec 06, 2008 11:51 am

Fatty wrote:ah, and housing size, i need to choose between .86 or .64. i'm clueless about which to go for, and what the numbers actually mean

Trust me, you need to choose .64, Fatty.
Take it from me (because I've done this) that that .84 will be too laggy on any 1.6 or 1.8.
Try full boost after 3,400 or 4,000rpm which is not fun for normal driving and the occasional autokhana day.
Hope this helps

Fatty · Postby **Fatty** » Sat Dec 06, 2008 12:15 pm

excellent. thanks guys, this is exactly the sort of info i need.

hmm.. do you guys reckon this is a good choice for my 1.6? i just noticed on the specs "Displacement range: 1.7-2.7L " ...

even with the smaller .64 housing will it be laggy? the reason i was looking at this turbo in the first place is coz i hate the lag in my old turbo (non ball bearing), i just want something that is heaps more responsive and thie turbo often gets mentioned, but no so much in mx5 circles...

Postby **mx52nv** » Sat Dec 06, 2008 1:28 pm

Hi Fatty (again),
As long as it's the Garrett GT28RS with the .64 rear housing then yes it is the perfect choice.
Please have a look at my mate Ian Lewis' race NA6 turbo (street registered) and the dyno sheet on there as well.
Heaps of low down torque and power.

Teaser pic

Fatty · Postby **Fatty** » Sat Dec 06, 2008 2:23 pm

cool.

thanks again guys.

Adam_NAclubman · Postby **Adam_NAclubman** » Mon Dec 08, 2008 12:13 am

Isnt the AVO kit meant to come with a GT28? For the BP kits at least anyway, and I doubt they'd use different flanges for the 1.6

I'm not entirely sure how to check what my turbo is meant to be, none of the markings on it seem to match anything on the Garret site

Blue94t · Postby **Blue94t** » Mon Dec 08, 2008 9:34 am

Adam,
The AVO GT28 is rated at 320hp if you believe AVO's specs and is commonly listed as a GT28R or a GT25/30
The Disco Potato is commonly listed as a GT28RS and is rated at 350hp. It is also known as a GT2860R.
http://horsepowerinabox.com/HPIAB2/turbochart.htm is a helpful chart for comparison.
FWIW I think the Disco Potato would be a brilliant turbo on either a B6 or a BP. There reputation for response is the stuff legends are made of.
Jake

Postby **Okibi** » Mon Dec 08, 2008 10:34 am

Don't let the nissan fanboys tell you otherwise, the "disco spud" was designed specifically by a Garrett employee for his own miata.

The disco potato name comes from a well known psychedelic coloured nissan it was put into.

bruce · Postby **bruce** » Mon Dec 08, 2008 11:04 am

Cool name for a turbo. Bit like putting together two totally unrelated words - "look at my new Knee Garden intercooler"

Blue94t · Postby **Blue94t** » Mon Dec 08, 2008 1:33 pm

Okibi,
You got that right, Jay Kavanagh was his name.
The story is here http://www3.sympatico.ca/mr2sc/disco_potato.html

See http://www.turbobygarrett.com/turbobyga ... og1of2.pdf for compressor maps and other info.
They say 1.8 - 3.0l, 250 - 360 HP.

Jake

ampz · Postby **ampz** » Mon Dec 08, 2008 3:16 pm

get that megasquirt finished Fatty and your lag issues will begone.
with EBC controlled by the ecu, you can have around 3 psi at 2000rpm (open downpipe) on a "potato" :shock:

Let's just say the trip around the block was a little quicker than i expected :mrgreen:

Now to finish the exhaust between hangovers, that's gonna be the hard part

Fatty · Postby **Fatty** » Tue Dec 09, 2008 4:52 pm

Adam_NAclubman wrote:Isnt the AVO kit meant to come with a GT28? For the BP kits at least anyway, and I doubt they'd use different flanges for the 1.6

keep in mind my kit is very, very old, and specs change over time.... it's academic anyway as the flange is the same.

Fatty · Postby **Fatty** » Tue Dec 09, 2008 4:53 pm

Okibi wrote:Don't let the nissan fanboys tell you otherwise, the "disco spud" was designed specifically by a Garrett employee for his own miata. .

never knew that, thats cool to know, thanks.

Fatty · Postby **Fatty** » Tue Dec 09, 2008 5:02 pm

ampz wrote:get that megasquirt finished Fatty and your lag issues will begone.
with EBC controlled by the ecu, you can have around 3 psi at 2000rpm (open downpipe) on a "potato"

this is a very good point.. and one that leads me back to the question about the housing .. .64 or .86. with the MS controlling the ebc boost will build a lot quicker than on some other setups... so lag shouldn't be as bad... so maybe i SHOULD go for the .86 after all ? ?

mx52nv, your thoughts?