300RWKW 4AGTE Turbocharger Selection

[boxh34d]

My figures come from my spreadsheet calcs, which are effectively based off garrett's calcs with some tweaking. Far from anything too in depth or earth shattering. There are some highly specific spreadsheets getting around, but as always the result is only as good as the info / educated guesses that you put in.
General rule of thumb is around 10 engine HP per lb/min of airflow. 300RWKW is 400 RWHP, which is probably somewhere around 450 to 480 engine HP, = 43 to 50-ish lb/min flow required. This tends to be pretty universal, with reletively minor variation between most engines I've seen.
Engine rpm, VE, BSFC, AFR, and post I/C temp shift (mainly) the pressure required, and / or (minor) airflow required to make the power.

[trdee]

Thanks for that box34d, appreciate it. So if I am aiming for up to a max of 50lb/min, that would then indeed mean i need a GT3076R if i want to cover 300rwkw on a garrett turbo. Or a GTX3071R..

Still cant find any proper compressor maps for IHI or precision turbos, or pretty much any brand other than garrett, so the only way i can really pick a turbo from the other brands is by going with their advertised horsepower targets..

[oldcorollas]

tbh, i'd just take it at 90-95% VE /atm intake pressue
and i'd be wary of using dyno results for making calculations... (reason being that dyno and rpm vary quite a lot, compared to torque)

reasoning..
stock smallport makes ~150Nm from 1.6L.
until recently, best road going engines were around 100-105Nm/L, so if we take 100Nm/L as 100%VE, then...

150/160*100= 94%VE, for 1atm absolute pressure. it might go down to 87% at higher boost.. maybe even less

300rwkw is what? 350 flywheel?
starting at 350fwkw, and using

kw = (engine size x 100 x (1+ boost) x rpm) / 9402
where engine size is in litres, boost is in Bar or atm)

and Nm = engine size x 100 x (1+ boost)
or Nm = engine size x 100 x efficiency (in %)

350=160*Ve*(1+boost) * rpm/9402

if peak power is 8500, and assume VE stays at 94%, then the torque you need to get 350flywheel kw is 387Nm
to get that, you need absolute pressure of 2.58atm = 1.58atm boost = 23psi boost.

that all assumes you maintain the stock NA VE all the way up to 23psi and 8500..... chances are it will be less (or much less) and need more boost.

in terms of "VE" relative to NA motor, if NA is 94%, then boosted at 23psi will be "242%VE" (not taking into account IC pressure loss)
(at 87%VE,, 8500rpm, 350kw at flywheel, boost would be 26psi+IC loss)

I'm not familiar with the adaptronic "VE" programming, but in the megasquirt, the VE is just a number and is affected by the "required fuel" you put in... ie, it just scales the fuel utput but the number itself is largely meaningless

as said above, air and fuel required for power is not stupidly affected by engine type etc.. with caveat of "technology fudge factor", but air is air, and fuel is fuel..
/rambling

[trdee]

87% is what I have been using as VE at peak power till now in the turbo calculator...

Yeah I may have been looking into it too much, box34d's figure of 50lb/min is probably close enough to be good enough to give me a maximum number to work with. I also know the turbo will need to work well in a range of 24-30psi or thereabouts. Both of these together point to either a GTX3071R or GT3076R, depending on how rich i feel when the time comes to go shopping (when the KKR dies)

[NME308]

Well if using the Garrett supplies formula's (which my brother did up in exel the champ!) it looks a bit like this:
Now I'm only hazarding a guess but if you are running standard head with big cams I'm wondering if peak power may be more likely to be in by around 7000rpm??? This is from a look around at other dyno sheets off the forum.
The new engine with decent cams - lets guess VE is 140% and power is 400hp THEN 40lbs/min is required at 22.5psi boost to do the job at 7000rpm.
Lets say peak boost is achieved at 4500rpm then 260hp should also be produced at this point requiring 26lbs/min.
Just a guess again here I feel your VE may start to drop off over 7000rpm say 7500rpm tops with standard ports just looking at other dyno plots. That said power would most likely be still available at 8500rpm on the track however I think the dyno will be nosing over before then.


To make a little sense of your current engine:
It appears to be making peak power around 6600rpm.
It is known to be using 17psi to achieve that.
This could be achieved with a VE of 130% and a BSFC of .5

There is XSVWGN with a somewhat worked over appearing engine making 358rwkw at 32psi and only 6700rpm.
This could be achieved with 150%VE and 0.5 BSFC.

This has all been calculated with the formula for regular petrol and I believe E85 will require slightly less of the LBS/Min airflow from the turbo.

Cheers,
Jason

[trdee]

i am currently making peak power at around 6600rpm but it hardly drops off at all beyond that all the way to 7500rpm on my dyno plot. with the cams i figured i ought to see peak power around the 8k mark, but lets say 7.5k anyway... so shortcut answer how much boost and airflow do i need so i can just pick a bloody turbo and be done with it?

[Ken_T]

Here's a weird turbo for ya, Holset HE351VE.


It's a variable geometry turbo which varies the exhaust housing between about 5cm^2 to 25cm^2. It will make the power you want (and more) while giving you the response you want, probably better too. There's a catch to this, you need to control the thing and it's pretty big. The ECU communicates with the turbo actuator via CAN, noone has figured how to control it with any ECU other than stock as far as I know. Been a while since I been looking into it and I dunno if I'll ever get to use it. There was talk of an aftermarket controller for the turbo but like 700 or so.

There's a guy just using a pneumatic actuator instead of the electric thing with decent results. I looked into controlling it with a high power servo and a PIC taking signals from MAP and TPS. Did some calcs and it should work but I don't have a car to put the turbo on. Flange is a goofball size but I have measurements and CAD drawing, you can't high mount it unless you cut one half of the actuator mounting tabs off which is not a problem if you're planning on controlling it with your own gadgets.

They could be had for cheap too, I got mine for 98 bucks years ago, usual going price was 250 on ebay but as I said before, I haven't looked at these things in a while.

Just something to look at.

[NME308]

Garrett says 40lbs/min airflow required.
Worst case I can imagine says 28psi boost (my personal guess is 24psi...).

Your previous musings of a turbo capable of up to 50lbs/min and 30psi boost seem to be quite on the ball park to ensure this puppy is covered in all possible ways!

Cheers,
Jason

[trdee]

ken - interesting, however

1) too hard basket in terms of controlling the variable vane stuff for a simpleton like me
2) i doubt it would fit in my engine bay
3) is this a diesel based variable vane turbo? i thought they had lots of temp issues when used on petrol setups?

NME308. cheers again for le' advice.

[Ken_T]

If you use a garrett VNT with the many tiny nozzles, they will jam and stick. The holset has one moving part that's in the exhaust stream, it's pretty simple and robust.

[trdee]

ah ok. still no idea how i would make it work or even fit for that matter though

[SHEPPO3930]

Not sure if this helps with your calcs, but a friend has a 4agte (stock big port head, built bottom end), gt2871r, and it makes 220kw on 15-16psi. This is by no means its limit, the tuning was stopped at this boost level due to maxing out the injectors (440's at 65psi fixed pressure). Apparently with 20+psi and more fuel 250-260kw and beyond wouldn't be an issue.

[Cuzzo]

I call shenanigans on 220kws on that boost level. Unless race fuel.

Vito look up the ae92 checkmate or talk to 300kw 4agte guy. follow his instructions and install.

[oldcorollas]

more holset pics
http://www.4btswaps.com/forum/showth...er-turbo/page3
and some say it works opposite to a normal "VNT" turbo in that it acts as an exhaust brake by closing up the A/R on braking..

The HE431V isn't vacuum actuated. The actuator is operated off of compressed air from the brake system. It works backwards from a wastegate actuator also. More pressure closes the VGT increasing boost. They do that as a safety, if the braking system or a line fails, it goes to low boost rather than overspeeding and grenading the turbo.

[trdee]

I call shenanigans on 220kws on that boost level. Unless race fuel.

Vito look up the ae92 checkmate or talk to 300kw 4agte guy. follow his instructions and install.

fandio made 228 on 17psi so it is possible, but that was with blacktop head and bazda plenum etc..