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Old 02-09-2010, 06:54 PM   #1
Dubstar112
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Default Theoretical power output of a td04

I want to know if there is a way to calculate, extrapolate, educated guess etc the power output of a td04 on a 2.5 liter motor, while making full boost(say..18psi) at like say 1500 rpms. This is a theoretical question and if you just want to ask WHY go else where. Also, say after that, Id like to figure the same formula using a vf43. I will do a little research on compressor maps etc, just searching for a formula
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Old 02-09-2010, 07:15 PM   #2
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You're asking us to make A LOT of assumptions for this theoretical exercise. Probably too many to give you any sort of consistent accurate approximation. :shrug:
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Old 02-09-2010, 07:25 PM   #3
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There are some good guides online that will teach you how to plot and read the compressor performance maps of specific turbos. Check those out.
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Old 02-09-2010, 08:08 PM   #4
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you talking about the stock TD04-13T or a larger TD04?
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Old 02-09-2010, 08:29 PM   #5
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Well, what do I need to search for? Too many variables? figure STP for starters! 13t

Im having a hard time keyword searching this kind of formula as I dont know what to call what im looking for.. any tips?

Can I extrapolate from rom raider logging what happens at 2900-3000 rpms at spool?

BTW i was not asking YOU to give me an approximation. Simply asking if it could be done.
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Old 02-09-2010, 08:30 PM   #6
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Did you read the Turbo FAQ?
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Old 02-09-2010, 08:33 PM   #7
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Did you read the Turbo FAQ?

The one in the newbie forum? Sure did
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Old 02-09-2010, 08:35 PM   #8
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Old 02-09-2010, 08:52 PM   #9
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Quote:
Originally Posted by Dubstar112 View Post
I want to know if there is a way to calculate, extrapolate, educated guess etc the power output of a td04 on a 2.5 liter motor, while making full boost(say..18psi) at like say 1500 rpms. This is a theoretical question and if you just want to ask WHY go else where. Also, say after that, Id like to figure the same formula using a vf43. I will do a little research on compressor maps etc, just searching for a formula

id say that 18psi is low for a td04...think more like 20-21psi

and stop wasting yer time with a td04 on a 2.5 unless you only use 1-2-3
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Old 02-09-2010, 09:31 PM   #10
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Quote:
Originally Posted by Uncle Scotty View Post
id say that 18psi is low for a td04...think more like 20-21psi

and stop wasting yer time with a td04 on a 2.5 unless you only use 1-2-3

I do only use 1 2 3. most of the time 1 and 2.

456 gettin no love from me! ololo

Last edited by Dubstar112; 02-09-2010 at 09:52 PM.
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Old 02-09-2010, 09:42 PM   #11
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Try to find someone with speed density Engine management and a TD04 on a 2.5L (this alone won't be easy). This will effectively already have what you want in two charts:
- 3D chart of VE @ RPM vs PSI
- 2D chart of VE correction @ intake temperature.

If you can combine those variables into an equation for VE, then you can apply already derived equations for VE into power, then you don't have to derive from scratch. You can just make an equation that approximately matches the empirical data already available.

Compressor maps are nice, but you need to combine that information with a turbine map and the various engine parameters (exhaust restriction, intake restriction, intercooler efficiency, etc...) to have anything more than a very basic idea of turbo capabilities.

The engine management VE tables of an ECU that uses speed density will have already done the combination of those variables for you (basically... and assuming it's tuned properly). This means your only task becomes describing what is essentially a 4D array in mathematical terms. translating a 4D array into a mathematical formula is not exactly easy, but it's a LOT easier than deriving such a relationship from the compressor map, turbine map, then making various assumptions about the engine characteristics.
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Old 02-09-2010, 10:36 PM   #12
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Ok, so, this particular issue will likely require me to start with the base setup tuned, or need some knowledge that isnt readily available. And could be a little bit too far out of my league.

Last edited by Dubstar112; 02-09-2010 at 10:41 PM.
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Old 02-09-2010, 11:06 PM   #13
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Quote:
Originally Posted by Dubstar112 View Post
Ok, so, this particular issue will likely require me to start with the base setup tuned, or need some knowledge that isnt readily available. And could be a little bit too far out of my league.

ok...since the td04 essentially acts as its own restrictor on a 2.5....

you could just tune it without any real boost control other than max boost---just let it go and do what it will and adjust fuel and timing to suite and see what ya get that way

i know someone who kinda did just that and it is quite entertaining
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Old 02-10-2010, 07:12 AM   #14
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I know you did I had a header and ewg on my td04 and it was quite a bit of fun during auto x. What Im aiming for is, better than insta spool. I was basically wondering with the known flow rate of a td04 and its powerout put diminishing above 4500 is there anything to be had below its current boost threshold?
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Old 02-10-2010, 08:28 AM   #15
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Quote:
Originally Posted by Dubstar112 View Post
I want to know if there is a way to calculate, extrapolate, educated guess etc the power output of a td04 on a 2.5 liter motor, while making full boost(say..18psi) at like say 1500 rpms.
So you just want to play make believe?
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Old 02-10-2010, 08:38 AM   #16
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only way you're gonna get that 18psi at 1500 is running anti-lag. normally in gear you will not hit that when you punch the gas pedal. your engine speeds will already have past 1500rpms. you need to load up the engine to produce boost.

unhook the wastegate line....... there are plenty if td04's to be had cheap!!
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Old 02-10-2010, 10:21 AM   #17
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I would say 22psi on a stock tdo4 is very possible and very fun. I actually went for a ride in a car (2.0 litre) setup tuned to this with a EWG setup to help with quicker boost and a little more tourque. And yes it is fun 1-2-3. For a 2.5 litre the boost will peak quicker but fall on its face quicker. I was quite impressed...

Fyi, he runs 13.7's trapping around 103mph on a stock clutch that slips if that heps give an idea...
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Old 02-10-2010, 03:26 PM   #18
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There was a thread on another forum where an 08 WRX, stock turbo, and DW850cc injectors, tuned on E85, broke something like 250whp. Add in headers, full turbo back, EWG, intake.... WHo knows? 260whp? Just a theoretical game to play, but what else is there to do when snowed in today!?
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Old 02-10-2010, 04:04 PM   #19
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..... braden at XPT tuning got 400tq and 270hp on the 08 WRX with stock injectors and e85 + walbro FP.... i ran the map, believe me its badass, but only till about 4k rpm then its no different than gas due to the TD04 pissing out, but meh it holds power till redline which is alright.

scroll down and hes got the dyno plot showing the 18.5psi e85 chart
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Old 02-10-2010, 04:08 PM   #20
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Quote:
Originally Posted by quazimoto View Post
So you just want to play make believe?

Yes. The only reason I havent mentioned the idea of antilag is all of you nay sayers chime in with gtfh noob not for u blah blah blah your stupid, it ruins everything etc..

So yes, I want to know if antilag on a td04, vf will provide generous torque below your normal boost threshold.

Im not building a widebody car to look good. i want it to play the part aswell.

Im not trying to run any ideas by anyone for approval. Im just doing... Albiet slowly cause its winter and fences dont go up in winter

Quote:
Originally Posted by scramjett View Post
There was a thread on another forum where an 08 WRX, stock turbo, and DW850cc injectors, tuned on E85, broke something like 250whp. Add in headers, full turbo back, EWG, intake.... WHo knows? 260whp? Just a theoretical game to play, but what else is there to do when snowed in today!?


Thats all good in everything, but my last setup made 241whp and 323 wtq.. Im not switching to e85 for 9 hp plus or minus the brand of dyno And from my experience a header will be negligable in most smaller turbo applications.. Im aiming for a significant expansion of the power band on the low end.. This time around I will have TGV deletes and a ported intake manifold to aid in squeezing everything out.

Last edited by Dubstar112; 02-10-2010 at 04:22 PM.
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Old 02-10-2010, 04:23 PM   #21
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I have an 08 wrx with the td-04. It us tuned to hit max boost at 18.5 psi. I am making 250whp and 325 ft/lbs tq.
Other mods include,
tomei header and uppipe,
aem cai,
megan racing dp,
perrin exhaust
and walhbro 255 fuel pump
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