Hi I’m interested in the professional opinion, of what the boost threshold is going to be like on a Garrett TO4Z with a 1.32 A/R. this turbo will be used on a 13B with very large extended street port. I would like to see 16lbs of boost by 4200-4500 rpm if possible. I am aware that the TO4Z comes in a range of other more desirable a/r but I use the car for drag racing as well as a daily driving this is way I would like some advice from some one that has used to4’s with a large a/r.

Thanks in advance
Erdin

 

Hi Erdin,

I've tried a 1.32a/r housing on my T04Z (mild street port), 16psi at 4.2k is right on the money (probably earlier). The 1.32a/r is fine for road use. Response is suprisingly good, not far off the smaller housings at all
Cheers

Rob

 

FRO,

Thanks mate thats what i wanted to hear.

 

I have a 1.32 on my TO4Z too

Real men run proper sized turbine housings

 

looks like 1.32 is the way to go

 

Are you guys only running 16lbs or how much total boost are you all running? Are you running 4" exhaust since your turbos are so large? Any pictures you can post?

 

I'm not swingin on your nuts or anything, but thanks for the new signature quote. I've been saying that for a while now!

 

Is your 1.32a/r housing divided? Do you have any dyno charts? How comparable is the TO4Z to the Aspec 500R?
Barry

 

Yeah that's a 1.32 divided housing Barry. I don't have any dyno charts, I never remember to ask for any and the car's been dyno'd so many times I can't remember which are with which housings (I have a 1.00 on at the moment but I'm switching back to 1.32)
I don't know the specs on the 500r so can't comment on any comparison there I'm afraid

 

Fro, since you have used both the 1.00 and the 1.32, how much lag/threshold difference is there between them?
Barry

 

We ran the 1.00 and 1.32 housings back to back on the dyno about a year ago, the 1.32 started spooling about 500rpm later than the 1.00. The larger housing felt a little laggier on the road but it wasn't significant.

Sorry I can't be more definite, it was quite a while ago. I'm hoping to get a 1.32 housing back on in the next few weeks before I run the car on the track again mid-May. If this happens I'll give an update

 

Is there a total HP change between the 1.00 and 1.32? ...or does it only move the power curve up/down and peak at different RPM's?

500R specs are extremely similar to GT35R. I beleive T04Z may be capable of more boost and power (>20lbs) but 500R has full boost about 500rpm's sooner at 14-16lbs. Note: This is from searches and not first hand experience with both.

 

Good call. You dont want to be fed to the pigs.

 

lots

 

Quite a few blokes have tried the 1.00 or 1.15 and found a fair percentage increase in power at same boost when switching to the 1.32a/r. Hence its the popular housing here to use if you want serious grunt with not too much loss of low/mid end power, but as with everything its a compromise.

 

i was runing 19lbs low boost and 20 + on my R85, yes that is with a 4'' exhaust.

 

Have any of you compared the GT40R -vs- T04Z? I'm actually only intending to run 15lbs and would be using a .82 or .84 trubine A/R. yeah, yeah I know too small for the big boys.

 

i'd like to see a video of some of these 1.32 T4 guys running in 3rd gear and just flooring the throttle from about 3000rpms. i'd rather see how quickly it actually gets up to full boost, not the rpm at which it is reached, as that can change dramatically depending on which gear you're in... see what i mean?

 

Then why run such a large compressor if you aren't going to boost more than 15lbs? Size the turbo to the application. if you are going to run 15lbs it makes more sense to run a smaller compressor with a properly sized turbine...then to choke down the turbine on an oversized compressor. This thread is a testament to that. Running a .84A/R turbine might provide slightly better spool, but it is doing so at the expense of preturbine back pressure...which isn't good for the engine.

Hope to have more (hard) data on this topic by the end of my engine build/tune.

 

^ Was told by Garrett that it wouldn't start choking from the smaller .84 A/R untill about 23lbs. The larger turbo would yeild more HP at lower boost. The smaller turbine housing would lower the rpm spool (threshold?). I would also be running 3.5" DP & exhaust. I beleive the GT40R has a smaller compressor then the T04Z.

 

I helped a mate tune his T51 half bridge 13B, it runs a massive 1.34 rear housing (makes a T04 1.32 look small !!!) has a R trim turbine wheel which is again massive massive massive.

On 20psi it pulls this boost from 5k rpm to 8.5k rpm and simply blazes the tires in 3rd gear across two lanes of freeway on pump fuel and water injection.

Big turbo's do work and are responsive, same car in gear in 2nd @ 5k turn rubber into gass particles

If you use too small a turbo/turbine your power will suffer everywhere except in the gay range of driving speeds rotaries are 5k onwards devices and anything but racing on a goat track or inbetween witches hats in a car park is more than covered with even largish turbo's.

I would NEVER run a T04 with anything but a 1.32 and that is the majority case here in Australia, you almost never ever see anything smaller than a 1.15.

 

^ Eh mate, had to translate that while I bbq'd some shrimp. I do the parking lot witch hat thing and by the time I hit boost I have to let off the gas. I don't want to pay for race gas every tank and i'm scared of relying on water injection for fear of failure. What good is a 1.32 or even a 1.15 if bost may never go over 15lbs and most certainly never over 20lbs?

The GT's are popular in the states and TO4Z is popular in Japan and apparenty down under.

 

water injection is the greatest reliability thing you can/will ever do when running a single turbo car, all my set ups over a long time now have never failed EVER.

boost, i dont run any cars under 20psi, this is low boost IMHO its a turbocharger, they are designed to be used not polished

this is not to detract form what your into or what you want but this is just how I do it and have been doing so for a long time now, others are slowly starting to catch on....... not much choice when their **** gets handed to them all the time and everyone talks (especialy their own customers!!!) about cars running the way you prescribe the set up

the amount of reliable power I can make is unusable on the road with any road legal tire *that will fit under a mazda* without fancy boost manipulation in first 4 gears or proper F1 spec traction control.

for your application unless you get over your boost paranoia and the use of proper proven technologies then you should be looking at very small turbo's like the GT35R

 

Rice, What is your preferred turbo manifold runner ID size? for a turbo like this.

 

I use 1.9" to 2.0" id with much sucsess

as with any turbo car a top level electronic boost controller with adjustable gain in gate cracking delay will yield more benifits than almost any fancy *mechanical/fabrication* thing you can do

experienced that graphicaly last night on the T51 tire destroyer!!!