Jump to content
SAU Community

Recommended Posts

  • Replies 84
  • Created
  • Last Reply

Top Posters In This Topic

Fatz you do have a couple of options here , first is to replace the .50 ARR comp cover with the larger .70 ARR T04E cover and keep the backplate .

Second is to use the larger series T04S cover and backplate (adapter ring) which is what Garrett did with their GT3540R turbocharger .

If your finances are limited go the larger ARR .70 "E" cover . If the sky is your limit go the "S" bits . Also remember that the T04S covers are quite large so make sure there's enough real estate where your turbo lives .

Generally compressor covers are sized around airflow rates or speed . So for a given compressor wheel the larger the Area Radius Ratio the lower the gas speed will be and vice versa . Also the larger it is the less chance it will have of being a choke point at high wheel speeds . Someone did tell me that all else being equal going up in comp cover AR brings the boost on a little later and "hits" harder .

With most Garrett turbos there is a set compressor wheel diameter for each wheel/cover family , ie 60mm wheels T3 covers , 71mm wheels T04B covers , 76mm wheels T04E covers , 82mm wheels T04S covers .

In recent years Garrett started going up a size in cover with some of the GT BB series compressors . I think this is because the comp wheels are mechanically stronger , and and can still pump efficiently at much higher rpm's than the bush bearing has beens . This is a win win situation , the small high speed wheels are compact , cheap to produce and more importantly have less innertia so spool sooner .

Examples of this are the little GT28RS (T04B comp cover) and some of the GT2835R series turbos with 71mm compressors and T04E covers .

The Garrett people inthe US tell me that the up sized cover , and a little extra tip height on the wheel , gives extra pumping capacity and a few more points compressor efficiency .

I can only think of two examples of Garrett turbos that went smaller in cover size , they are the HKS GT2540 and the Ford GT3540R . The 2540 is getting on and was probably an attempt to get a bit more flow and power out of a small series turbo , and a low mount compact (convienent) fit for GTR's .

Its safe to say Ford was not looking for serious performance with the XR6T so a compact and probably cheaper adequate cover got the nod . You can bet they knew people would modify them for performance , so the limited cover capacity may have been intended to limit the performance with the std turbo but not affect the standard state of tune .

Cheers A .

yea just stuck a side pipe on the beast and took it out to the drift day

sadly budget has died in the arse so i will have to putt around for some time until a set of cam gears arrive and the powerfc which is probably about 3 months away

im quite happy with the power but as soon as those cam gears are in hopefull it will bring it on a bit better

if cam gears dont bring it down to 4000rpm with power fc and a decent tune then i will consider the upgrade to external wastegate and a .86 rear housing and combine it with the larger front cover

but hey im happy as a pig in shit at the moment and when i win lotto ill do the next big upgrade

ive also got a rb30 complete engine that will be getting a solid bottom end over the next few years to replace the gtr bottom end when or if it ever goes

yea baby

anyone have some cheap cam gears

pete

  • 5 weeks later...
  • 2 months later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • When you crank your car, and hit it with a timing light, can you see a steady crank timing?
    • Oh, forgot to add, A few months ago I was getting mixture codes and the car was using crap loads of fuel. You could smell the unburned fuel in the exhaust, it was crazy strong. Economy was over 17.5 l/100 and usually around 19. I smoked the engine and found a leaky CCV hose which I replaced and then I replaced my two pre cat O2 sensors, I also replaced the MAF. This fixed my mixture codes and improved my exonomy but I'm still 14 - 15 l/100 when pottering about town so something is still amiss. Throttle response is much better and it has more pep but I'd like to know why it's still so thirsty (and I'm hoping that whatever it is gives me a bit more poke).    
    • Car is on factory injectors/z32 maf/ q45 throttle body/ z32 ecu with nistune 
    • Hello all, currently finishing up a rb25 swap into my s14. Having issues with starting, car has spark (confirmed by pulling a plug and watching it spark), has fuel(confirmed by checking pulse/voltage at injectors all spark plugs are soaked in fuel). Car cranks over and pops into the exhaust with a heavy fuel smell but no attempt to start or run, I have torn the timing cover off and triple confirmed timing, turned the CAS in multiple spots both directions, attempted to start with coolant temp and maf unplugged, checked my fuel lines and made sure they weren’t backwards, checked voltage at cas/injectors/coilpacks, made sure all the grounds in the harness are connected and added a few grounding straps (1 from chassis to block, 1 from chassis to head, and 1 from chassis to igniter chip) I am getting stumped here. As a last ditch effort I made a full grounding harness tonight that’s going to run from the battery and add an extra ground from the battery onto the coil pack harness/igniter chip/ intake manifold/ Wiring specialties harness ground/ and alternator. I’m hoping maybe the grounding harness will fix it here but posting here to see if anyone has any other ideas on what else I can check. My fuel pressure is unknown right gauge will be here tomorrow.  IMG_3206.mov
    • yeah I was shocked when I checked my spare OEM on and as below that's how they come from Nissan. (side interesting note new NEO gearbox and replacement park lack the brass bush on the tips and its just all alloy) unsure about damage to the box currently back at 1110 to be pulled down/inspected and selector fork replaced as he built it previously and given the never before seen failure on his billet forks he is replacing it under warranty. He said he has used always OEM the keyway tab without issue for years so it could be an unlucky coincidence. I did talk to him about the sharp corners and stress concentration too. Re: hard shifts i got 7+ years out of the OEM one and the fork itself failed not the keyway. so could be bad luck as I said or an age thing + heat cycles in box and during fabrication of billet?
×
×
  • Create New...