3071 Garrett

[BHDave]

i never had an issue with the stock air box in my 32. I modded it with a 4 inch CAI.

My combo hasn't held steady boost ever. original 1 bar actuator, then enlarged wastegate and 16psi actuator. Then i put the car into a wall before going ex gate so the turbo is sitting on the garage floor atm...

Anyone want a garrett .63 IW housing with 38mm wastegate flap???

[Cubes]

Bugger.. Mine holds steady boost until I try and push more than 17psi

I also have a 4" cai in to the bottom of the airbox but thinking maybe the paper filter is causing issues combined with the 2" fmic piping etc..

First up it will be run with just the fmic done then if there's still issues I'll lift the lid on the airbox if no joy then on goes the actuator which will be going on regardless as I don't really want to run any less than 18psi.

[skylinecouple]

Just wandering if the AFM is simply not passing enough air as in the States these 3071 compressors are running 22lbs of boost no problems. I want and will have 18lbs across the whole rev range, full stop. Got to get me some cams, 16lb actuator and finish my airbox.

[Cubes]

Depends on the power they are making at 22lb/s and on what motor.

More than likely related to the IW setup in your case. Get a stiff actuator on it or a split dump so boost creeps

[zebra]

Cubes -

Who Did Your re-grinds?

Im assuming they were done in Vic...Anyone Recommend Someone in QLD who can do the Job?

Also noticed on ATPs Site that they have Split-Pulse T3 GT30/35 Housings for $295us And then I guess you could modify a cheapy stainless exhaust manifold and have a budget Twin-Scroll setup for your RB *ponders*

[Cubes]

Tighe cams in QLD.

[zebra]

Thanks, I thought They were up here

[zebra]

Just got Quoted $1000 bucks for a set of cams from Tighe....Lame...was also told that if i wanted regrinds I would have to f**k around with the lifter preload and valve lengths and would cost more to regrind the 25 cams and would be easier to do it with RB26 Jobbies...so much for the price looking good compared to poncams.

[discopotato03]

Is this to weld (build up/harden/grind) 25 cams ?

What Tighe grind ?

Cheers A .

[zebra]

That was for what ever I wanted between 256 and 264 deg total duration.

And yes it was to build them up to be reground...was told to start with GTR cams as they are easier to do (less welding etc)

Cheers

Andrew

[discopotato03]

So whats the going price for new Poncams ?

Sorry OT , cheers A .

[zebra]

$800 delivered + JDM CRED = priceless

But Yeah, thats for the 256deg 8.5mm lift NVCS friendly ones.

this really needs to go in the Cams Thread....

So Im just going to mention my plans for a I/G .82 3076 right >> here <<

[dano4127]

Tomei Pon Cams with Tomei Cam gears for $802.65 + Delivery

Edited July 31, 2008 by dano4127

[Cubes]

Well that sucks... When I was sorting out mine I was told otherwise.

$380 for regrinds for either rb25 or rb26 cams to build up and then grind.

I picked up a set of rb26 cams for $60 and had them done.

[discopotato03]

Starting cams thread

A .

[skylinecouple]

Just thought I would give an update on an old thread. The setup has been in now for a little while and I must say it took a little patience with tuning to get the best from it. Have recently gone back to The Hitman for a tune as Yavus wasn't available. He put a fair amount of time into it and I must say it is just fantastic. Interestingly, I found there was a slight miss at idle and checked every vacume hose and fuel line as well as spark plugs but no problem there. Matthew aka: Hitman was slightly puzzled as the engine is very healthy. I am only talking about a very almost inaudible miss.

Over the next few days I remembered having to screw in the Idle air control screw on the rear of the manifold to get the car to idle properly as it was revving too high going back a year or two ago. This was after croydon tuned it, enough said. So I started winding out the screw and low and behold, the car comes to life. Seriously, Comes onto boost at 3,000rpm hard. Almost as responsive as my GCG hi-flow. Off boost is simply amazing as there always seems to be some power as long as your over 2,000rpm. It confounds me why making the idle leaner by four full turns has made such a difference considering it has been tuned for the right air from idle. I'd be keen to hear any ideas or theories.

Fuel consumption seems to be in general around 400k's for city with one or two expressway runs for say 30mins. On a trip I can expect 500k's easy. Flooring it in second is useless and you have to be perfectly straight in third to hook up, slightly turning the wheel will result in more smoke. Throttle control out of corners is my best friend but thats where the .82 housing really helps. Just makes it a little more controllable. I don't know how anybody with a .63 housing could enjoy coming on to boost so early. Clearly with the response this housing has the .82 is the ideal turbine housing for the RB25. I was so tempted to go with the 3076 and even ordered one but now am happy with 264rwkws and instant boost.

[discopotato03]

So , it's interesting that someone tried the 0.82 A/R IW turbine housing on a GT3071R - and on an RB25 as well .

It sounds like the pay off is less exhaust restriction so a bit more engine torque low down . I reckon the lower gas speed through the turbine housing means it's easier for it to make the right angle turn and flow out through the gates port when the flat valve opens .

I know exactly what you mean when you say there's always some power there - but over 2K revs .

This is pretty much what my old FJ20ET did with the larger of the two available turbine housings (0.86A/R vs 0.64) on my GT2860RS - only it started to go positive pressure wise at about 1700 + .

The term I coined and Joel will rember it is the "windmill effect" , basically I think well matched BB turbos idle or windmill fairly fast compared to bush bearing ones so rapid transients (accelerations/decelerations) are possible at low engine revs . I think it's possible that the turbo can pump slightly more air into the engine , even at less than ambient inlet manifold pressure , than atmospheric pressure can do by itself . If you managed to log your AFM voltages before and after you changed the housing size it would tell the story .

Also by having wide open throttle at lowish revs means the available pressure can more completly charge the cylinders , the turbine housing being less restrictive means the exhaust gasses are more likely to go south rather than have partial reversions into the cylinders . Best mean torque ignition timing at this stage probably means more efficient use of the air and fuel and less chance of detonation .

I know Joel won't necessarily agree with me here but I think he could achieve similar gains if he swapped his 0.82 A/R GT30 turbine housing for a 1.06 A/R one . Actually I think the difference would be slightly less on an RB30 in an R32 because the rod stroke/bore stroke difference and the lighter car .

Also turbo wise his GT3076R's port shrouded compressor housing would tend to mask any negative effects of a housing thats possibly a little small for a 3 liter engine . I doubt HKS would have gone to the expense of fitting a custom port shrouded comp cover to their GT2835 pro S turbos , there must have been enough gain to justify the cost of having such a comp housing cast and machined .

A short time back I was looking into Garretts bush bearing GT3571 turbos and I think I found a pic of one with a port shrouded T04E housing on it , from memory it has the slightly different series housing too - BSK1 ?

Cheers A .

[skylinecouple]

Forgot to mention I had too little tension on the actuator and this was causing loss of boost but all ok now. Only loses 1lb at the top end but this is one of two things, comp running out of flow or cams can't flow enough air. Who cares, enough power now so happy and will only change these stock cams if I get bored. Which shouldn't be too long. Can't help it. Your right Disco, I think Joel would be surprised at how a bigger exhaust housing would allow his compressor to flow more. Not just at the top end but through the entire rev range as I have found. I will never buy another turbo combination that has big compressor and restrictive turbine housing in the belief this will give me response. Actually, for Joel a 3582 1.06 housing would be perfect. Do they make this combo ? By the way, Matt says in his vast experience if I go from 3" to 3.5 or 4" dump and 3.5 all the way to the rear I would gain some more top end, around ten killer wasps. Well, I can sort of see what he means as the dump is only a bell mouth going into 3" then 3" all the way. Maybe for fun I'll do both cams and whole new exhaust to play some more.

[Cubes]

haha Adrian.. Your on the mark. I really like the mid range the .82 punches I really am afraid the 1.06 would feel

I really don't think the GT3076r has any use for the 1.06 as the comp side can't really take advantage of available exh. flow especially with the availability of E85.

The 1.06 on the GT3040 by all means definitely. Then I think bah to lazy the GT3040 1.06 you may as well jump to the GT35r .82 which has a 'similar' turbine flow to the GT30 running the 1.06 turbine housing.

-----

Gary..

450hp at the flyheel or more with either a split dump that re-joins the exhaust flow or bell there are gains to be had. Run a screamer or 3.5-4" exhaust and you'll see a solid 10+rwkw increase when up over 450hp at the fly (260-270rwkw+) so yeah.. Matt knows what he's talking about.

When you say too little tension.. I've wound the rod in so the top end holds 16psi (up .5psi) but now the mid range runs 17.4psi peak. I could wind in more but I really think my problem is a dodgy actuator.

No doubt there will be a point where boost begins to creeep up top due to the reduced flap opening but I don't like the idea of that method of boost control on a cold night.

When set correctly with 2-3mm tension on the actuator it runs 15.5psi with that being made at 4500rpm and 11psi at 3000rpm. Turn the EBC on and 19psi at 3000rpm no problems. Lazy actuator.

I'm fitting up an 18psi actuator soon so it will beinteresting to see if it rods of the lazy boost build when the ebc is turned off. The EBC literally makes 19psi (which its currently running through its mid range) a full 1500rpm earlier so something must be up with the actuator in my eyes.

[discopotato03]

Cubes I reckon a lot of the boost control problems stem from higher than necessary pressure between the exhaust ports and the turbine .

If the pressure gets high enough it will muscle the flat valve open purely because its higher than the combination of the inlet manifold pressure and the actuators spring . In this situation it's trying to act as a pressure relief valve rather than a device to regulate turbine (and therefore compressor) speed .

A wastegate actuator tries to regulate turbine speed by acting on boost pressure in the inlet side , provided the hot side pressure is not too far above the cold side pressure it should stay in regulation .

I would have thought that an RB30 is more than capable of making low to mid range torque with little or any boost low down , in fact I reckon with a bit less turbine housing restriction it would make similar to what it does now without boost so you could move the turbos speed range a bit higher in the engines speed range without losing a whole lot .

A larger turbine housing will make for better off boost performance IMO because the engine should be acting like a more efficient air pump .

Back to the maps , Garrett quote Hp figures for their turbos based on air flow performance . They don't say anything about how the range of turbine housing sizes affects Hp - though people should be able to work that out just by looking at the turbine flow maps and noting what the lines indicating each size show by comparison .

Have a look at the GT30 turbine maps and note what the flow differences are for .63 .82 and 1.06 sizes , ~ 20 , ~ 23.5 , ~ 26.5 corrected lbs/minute gas flow . So obviously the larger the housing size the less pressure exists inside it for a given exhaust gas flow rate . If the gas velocity is reasonable then yes the wastegate will work as intended , it should also be able to keep the turbine "windmilling" fast enough - lets face it BB cartridges were designed to have a lot less oil sheer drag than bush bearing ones .

Reading between the lines I'd say you can forget about getting anywhere near a turbochargers air flow/horsepower potential without its largest available turbine housing size . The compressor may attempt to cram it in but the spent gasses also have to escape and they all have to go through the turbine or wastegate . A small ratio housing with a bionic actuator can't work because as soon as the elevated exhaust side pressure forces the gate open the compressor speed doesn't increase so boost pressure has to drop . Creep I suppose you call it .

I agree it is a juggling effort to balance turbine response against exhaust gas flow but the engine likes it when the restrictions are low .

I remember when they were first playing with GT4088R's in the US (admittedly in twin scroll form) every time they went up in turbine housing size they found they could make the same power with less boost pressure - basically if you get get the bad stuff out quickly/efficiently the effort to get the new stuff in is far easier . Makes sense to me .

Back to the GT3071R , I was just looking at the maps for them and the comp one shows around 46-47 lbs flow capacity so easily enough for 450 engine horse power .

I know of examples in the US of built up SR20's cranking 450 Hp/400 lbs torque so the turbo obviously can do it provided the engine is modified to handle the gas flow requirements . These engines had a lot of head work and reasonably healthy cams in them so its not just a bolt this turbo on a tune with a big fuel system scenerio .

If you want it all you must have the head reworked and do the camshafts as well .

My own RB25 is std mechanically and the Sin Kid head is almost finished , it will have Poncams and the static CR up around 9.2-9.3 in an effort to make the engine a bit more grunty down low and at small throttle openings . I want my engine to stand on its own two feet and not need boost (or exhaust restriction) at low revs . I want it to feel like a larger capacity N/A engine and also don't want it to jump into boost at any great rate - don't need the "rush" .

Out of time , have a date with a long string of shipping containers , cheers A .

Actually have an interesting link to an Aussie fella that does well rallying Rexes and his ideas on turbo dump pipes

http://www.msengineering.com.au/exhaustsystems.html

Edited November 8, 2008 by discopotato03