Stock 4AGE Smallport Turbo Choice please

[feral4mr2]

I like high c/r and boost. Many have done it, some have failed miserably but many have succeeded with great reliable results. Having a aftermarket ecu to tune it right will be the best thing when running higher c/r. Though I always like to push the boundaries with stock ecu's... haha
I have a 4agte that still runs the standard low c/r 4agze 8.0:1 c/r pistons, combined with a GT2554r baby ball bearing. That things spools very fast and rather aggressively, but I still feel I want quicker response for what I want to use the car for (aw11) which is mainly gymkhana cone events (when I get the chance to get up to the city) and the aw is a heavy lump for it's size. I'm going to a small port head with a 0.5mm TRD headgasket which will bump the c/r up a little. am keen to 'feel' how it goes. If all else I want 'more' i'll drop the engine and put a set of higher c/r pistons in. Knowing me i'll be best to get some 8.9:1 4agze piston (cant keep my fingers off the boost controller), but it will be hard for me not to just put in the stock 4age 9.4:1's I have sitting in my shed as I've run these pistons under boost before. The main thing I still need to do though is save up and purchace a tunable ecu which will most probably be a Haltech sprint.

[trdee]

trd headgasket is 0.8mm only iirc?

also another option for improved low end response is of course to slap a 7A bottom end onto a GE head

also just to clarify my earlier comments RE T25 vs TD04 - i was talking about used T25 turbos off things like S13s etc, not a new GT2554R. those are a whole different kettle of fish

also x2! the TD04 doesnt like boosting much past 12psi. It will do it of course, but it becomes a case of diminishing returns very quickly

[feral4mr2]

this is the one I got..
http://www.ebay.com.au/itm/TOYOTA-4A...item43c94ea4b5

[trdee]

Ah yep, it is in the TRD listing

http://www.trdparts.jp/english/parts_engine-4a-g16.html

[maj]

also x2! the TD04 doesnt like boosting much past 12psi. It will do it of course, but it becomes a case of diminishing returns very quickly

Mine would boost to 1 bar reliably anything up to 5,000rpm, after that it would taper off a little but rarely below 0.8 until close to redline, unless I was getting soak.

Not that I don't agree with you, we're talking different engines and tuning here, and turbo setups vary enough as it is even on the same engine.

[trdee]

you arent disagreeing with me, because 1 bar is 14.5psi and 0.8 bar is just under 12psi, which clearly demonstrates that the turbo is able to boost past 12psi but it doesn't really like it, which is why it was choking up top as the turbo went out of its efficiency range

[maj]

Or the wastegate actuator sucks Which was a common upgrade but I held off because I cared about long term longevity of the turbo. Factory boost control was only mild too.

It was definitely out of its league by the top end though. Different engine, different results.

[knightrous]

also x2! the TD04 doesnt like boosting much past 12psi. It will do it of course, but it becomes a case of diminishing returns very quickly

We should probably nail down which TD04 / T25's we are talking about since there are a few versions and they perform differently.

The TD04's I have are TD04H-13T's from the 2005 2.5L Forester (Part# - 49377-04502, same as WRX of that era according to the NAISOC forums).
From the couple of looks at the compressor map and a run through the motorgeek "turbo" calculator (to get a ball park flow figure), the turbo should be able to run 18psi (361CFM @ 7500RPM) and still be in a relatively good region on the map (73% VS 76% peak). Running past that seems to be where it really dies off. I really dread to think of all the 2L/2.5L WRX/Foresters running them at 18psi >.>

Side note: Punch in all the 4AGE @ 18psi details into the motorgeek calculator then plot it onto the GT25R (GT2560R) and damn does that look bad compared to the TD04H-13T :O

[maj]

Mine was a TD04HLA-19T

[trdee]

My experiences are with early 2000s WRX turbos. Not sure how they compare to the one you have chosen knightrous. Another thing to consider is the accuracy of those CFM figures. When I was doing turbo sizing I found all the engine calculators wouldnt give realistic figures unless I entered some retarded BSFC/VE figures. I was given a guide of roughly 10lb/min for every 100HP by boxhe4d and that seemed to line up much more accurately with real world figures.

Using the 10LB/min for 100hp numbers, at 18psi the engine should be capable of flowing 449CFM (for roughly 180rwkw with a 25% drivetrain loss assumption) which puts it well outside the choke line on that turbo. *disclaimer* i just calculated this all very quickly without checking and there may be some errors in there, dont hurt me if i did *

Also a garrett 2560 is a bad choice all round, they are a very old design turbo

[knightrous]

My experiences are with early 2000s WRX turbos. Not sure how they compare to the one you have chosen knightrous. Another thing to consider is the accuracy of those CFM figures. When I was doing turbo sizing I found all the engine calculators wouldnt give realistic figures unless I entered some retarded BSFC/VE figures. I was given a guide of roughly 10lb/min for every 100HP by boxhe4d and that seemed to line up much more accurately with real world figures.

Using the 10LB/min for 100hp numbers, at 18psi the engine should be capable of flowing 449CFM (for roughly 180rwkw with a 25% drivetrain loss assumption) which puts it well outside the choke line on that turbo. *disclaimer* i just calculated this all very quickly without checking and there may be some errors in there, dont hurt me if i did *

Also a garrett 2560 is a bad choice all round, they are a very old design turbo

I was mostly using the calculator to generate the flow figure (I'm far too lazy to find the formula and calculate it repeatedly), not as a "You get HP X from Y Turbuleh" . For your figure of 180KW, it's definately way in the choking zone of the TD04H-13T. IIRC, 150KW only requires ~360CFM (close to 18psi @ 7500rpm) which is within the safe zones on the map.

[trdee]

Yeah that sounds about right. IIRC finney was making somewhere around 140kw on 1 bar and 160kw on 18psi. diminishing returns

[fixeruperer]

its a shame them V5 vortec blowers are so expensive, i think one would be mint on a 4ag.

[JustenGT8]

Since when did you have a turbo 4A???? If you want specific info on stuff feel free to PM me. I have quite a bit of experience in this field now
.

LOL since when didn't i

[trdee]

I don't know you tell me