Right Guys, I'm buying a To4Z... what ar should I go for??

Hi Guys,

Right I have a source for a really good price on the TO4Z, So I am going to go for one...

But the question is.... what AR.

I had a GT35R with a .68 housing and this was good but it ran out of puff at around 6.5k,

GT4088R with a '68 and it was too small; poorer response than the GT35R and not much extra power... worked really well on '84 housing. I also had a divided .96 and it was a lag monster.

I have a T67 with a '87 housing and this makes good power, and lag is livable.

New turbo will be either T67 on a cast manifold, or TO4Z on a cast manifold, whichever works better...

but what size ar to go for... I know chiefgroover went for the 1.00 ar which he says is pretty responsive...

These are the options;

T4_Divided .70

T4 Divided .84

T4 Divided 1.00

T4 Divided 1.15

T4 Divided 1.32

T4 Divided 1.59

T4 Undivided .61

T4 Undivided .70

I'm feeling the divided .84, shame the cast manifold is not divided.... wonder if I could weld a plate in there?

do you think it would give an added spool?

questions, questions

I'm feeling the divided .84, shame the cast manifold is not divided.... wonder if I could weld a plate in there?

When you say cast manifold are we talking Arnouts type here?

If you make it divided boost control is going to have to be reworked

Definately T4 Divided 1.32

It will spool very good and make decent power.

Anything smaller and you will probably want to go bigger at some point.

The smaller A/R's will choke up top.

I'd go T4 Divided 1.00 AR, this is the same HKS spec in their kits and gives a good balance between response and power.

When you say cast manifold are we talking Arnouts type here?

 

If you make it divided boost control is going to have to be reworked

Good point!

Really...?, so large???

The only experience I have with big ar's wast the GT4088R '96 divided and it was almost undrivable..... Yet Ernie did say his 1.00 ar response was excellent.

any actual users out there?

PM's sent.. thanks Nic

Definately T4 Divided 1.32

 

It will spool very good and make decent power.

 

Anything smaller and you will probably want to go bigger at some point.

The smaller A/R's will choke up top.

Thanks bud, but from your recent spec I can imagine that top of your list will be power!! I actually need to drive this thing round a track on slicks, so response is always more important to me, I'm no drag racer....

It may spool fairly quick still... but throttle response on 1.32 must be unlivable... have you used this setup??

Thanks bud, but from your recent spec I can imagine that top of your list will be power!! I actually need to drive this thing round a track on slicks, so response is always more important to me, I'm no drag racer....

 

It may spool fairly quick still... but throttle response on 1.32 must be unlivable... have you used this setup??

We fitted the 1.32 divided to a friends a couple of weeks ago. I think it spool pretty well, but if you track the car I'd say go with 1.00 divided.

You won't find a more efficient turbo than the t04z, it will outspool anything of the same size.

But don't go smaller than 1.00 divided, it WILL choke up top and it won't feel as strong, nor be as fast (if you decide to turn up the boost.)

We fitted the 1.32 divided to a friends a couple of weeks ago. I think it spool pretty well, but if you track the car I'd say go with 1.00 divided.

 

You won't find a more efficient turbo than the t04z, it will outspool anything of the same size.

But don't go smaller than 1.00 divided, it WILL choke up top and it won't feel as strong, nor be as fast (if you decide to turn up the boost.)

Sounds like the 1.00, and I'l be using 1.55 bar max.

Id go T4 Divided 1.00

The cast manifolds are not divided.

I currently run a divided turbo on an undivided cast manifold and the housing has a crack on the divided part, it was explained to me that this would be a hot spot in the exhaust. Think of it like sticking a pen across the turbo flange, its going to get pretty hot.

Just a thought.

The crack hasnt hurt my setup though.

The cast manifolds are not divided.

 

I currently run a divided turbo on an undivided cast manifold and the housing has a crack on the divided part, it was explained to me that this would be a hot spot in the exhaust. Think of it like sticking a pen across the turbo flange, its going to get pretty hot.

 

Just a thought.

 

The crack hasnt hurt my setup though.

I had thought of this, and had planned to cut the divide back a bit, or at least take the sharp edges off....

you can get an undivided .61 and .7, but that seems abnormally small... are divided and undivided measured in a different way, even so It seems very small...

looking forward to getting the cast manifold fitted either way, have struggled with the tubular one for a while, for a number of different reasons.

Has anyone been through a set of compressor/turbine maps for a T04z and worked out the figures if used on a supra? Might be worth knocking up some figures Mike

Has anyone been through a set of compressor/turbine maps for a T04z and worked out the figures if used on a supra? Might be worth knocking up some figures Mike

mmm... sounds like you are volunteering if you understand the map math!!

My usual technique is to buy 3 housing with the tubby and try them.... expensive but you always get the right result

mmm... sounds like you are volunteering if you understand the map math!!

 

My usual technique is to buy 3 housing with the tubby and try them.... expensive but you always get the right result

ha ha will see how things go today, I have all the stuff here to draw some up, although do HKS release there maps to the public?

although do HKS release there maps to the public?

They are garrett units

you can get an undivided .61 and .7, but that seems abnormally small... are divided and undivided measured in a different way, even so It seems very small...

The undivided are smaller as there is less surface area due to divide not being in the way. To get the same flow through a divided unit you have to increase its size.

I think I explained that right

They are garrett units

but with different exhaust blades and possibly impeller blades..

to think I would be buying another 4088r with £600 quids worth of HKS livery... hell no!!

the non divided is still small from what I know with Garrett and BL turbine a/r housings.. hence I'm curious as to why so small.

if there is some math behind the maps/2jz specific it would be an interesting read!

HKS T04Z - your best idea yet.

the non divided is still small from what I know with Garrett and BL turbine a/r housings.. hence I'm curious as to why so small.

When a/r are generally quoted on here they are mostly divided thats why the undivided seem small.

I have been looking for a flow rate comparison but so far been unsuccessful

Ok I have just had this explained to me in rough terms

An undivided .70 would be similer in top end to a divided 1.00, if the divided 1.00 was used with a proper split pulse divided manifold it would spool quicker the the undivided setup but overall power should be close.

This is the same for the undivided .61 and divided .84.

When you use a divided housing on an undivided manifold they have similar characteristics except the top end flow would be reduced as the divide becomes and obstruction, some people get round this by knife edging the divide to help flow.

Hope that makes sense

If and when I try a T04Z I would give both undivided manfolds a go on my cast setup.

Its a lot more work for me as I dont have any water lines in place at the moment

Thanks Wez, that's really useful info.

You know I think divided manifolds are only any use if you use two wategates.... My BL divided manifold uses two runners from either side that then merge, so the two sides are always linked. So I think inless you use a two wastegate system then you may as well just use a non divided...?

I will possibly get the non divided .7 and the divided 1.00. Ernie is going for the housing smaller than the 1.00, so he is downsizing.. he says the 1.00 never runs out of puff even at his suicide limit of 8.5k.