David_Wallis

I'd ask whoever mapped it..

David

dowser

I had a similar answer, but thought it too rude

David_Wallis

I was being serious.. It all depends on how its mapped... if Id have done it then about 30bhp.. yes thirty..

David

R19KET

I'd be more concerned about running a VF22 at 1.6~1.8bar.

Apart from that being WAY outside it's efficiency, I'll be amazed if it holds together for long.

Mark.

Denzil_Dog

you should see an improvement of about a half...
no make it about a half and a quarter....

in fact make it two thirds...

give or take an eighth....

hunlimo

Thank you guys that helped a lot

R19KET

It's not quite that easy. No one on here, or anyone I know, will have tried running 1.8bar on a VF22 turbo.

A little more info would also help, such as what size injector you have, at what RPM do you expect max power, and are you using standard cams/standard heads, what year are they, is it a "real" 2.2lt, or are you using an EJ25 crank, giving 2.122lts (approx)

Mark.

hunlimo

Whats wrong with the vf 22?

Andy.F

Shock ! Horror ! TD05 in VF bashing scandal

dowser

I've got to send my AP22 back - it always seems to read too high since the 05 install...I still have ridiculous 4th gear figures.....

Richard

R19KET

John,

Our engines are far more efficient than 75%. Even 85% is conservative.

Again, only a rule of thumb, you need circa 1.5CFM, and 5~5.5cc's of fuel, per 1BHP.

Mark.

john banks

Mark, do you have any data on typical VEs (without doing head work)? 85% at 7000 RPM is impressive to say the least.

dowser

I'd be interested in seeing difference for inlet manifold work too

Richard

R19KET

John,

I don't have any official data, but most modern engines are pretty efficient.

Let's use some of you figures as an example.

Based on all your testing, you estimate that you have circa 350bhp at the crank. You run a max of 1.3bar, and have an rpm limit of 7000rpm. You have 550cc injectors, and run a max of about 85% IDC (IIRC this info is pretty close).

So, using the info we have, and the equation for working out engine air consumption, based on "75%VE". EJ20 is 121.7CI.

121.7 x 7000 x .5 div' 1728 = 246.5CFM x 75%VE = 185CFM

185CFM x 2.3bar = 425CFM div' 1.5 = 283BHP.

OR: 121.7 x 7000 x .5 div' 1728 = 246.5CFM x 90%VE = 222CFM

222CFM x 2.3bar = 510CFM DIV' 1.5 = 340BHP.

OR: 550cc x 4 = 2200cc x 85%IDC = 1870cc div' 5.5cc = 340BHP.

Obviously, you would allow some margin for error, say +/- 10%, but these are "consistantly" VERY close.

Mark.

john banks

Thanks Mark. What were you trying to say/not say Andy?

Andy.F

Pretty much exactly what Mark said but using a longer and more confusing calculation Adding that once you hit the choke line on the turbo compressor, the formula can be a bit misleading. ie if you substituted 1.6 bar in these calcs you would not achieve the calculated results.
This is due to the wastegate shutting in to achieve the boost pressure, overall system pressure increases but airflow does not, in fact it may well decrease.

R19KET

Andy,

The formula isn't really misleading, but how people read, and interpret a flow map "is".

All the formula does, is tell you how much air an engine can consume, at a given boost, and RPM, so that you can work out what you need to do, to achieve a "target" BHP. Then you have to choose a turbo capable of supplying the required air flow.

Mark.

Andy.F

I'd agree with that

(geez, I'm getting mellow )

Andy.F

Mark

When designing a hybrid, the easy bit is the spec of the compressor. How do you ensure that the exhaust turbine is capable of supplying the necessary torque to drive the bigger compressor ?

If the turbine is incorrectly speced, then the virtues of the compressor may not be fully realised.

R19KET

Andy,

If you're working with VF, or TD turbo's, you're a little limited. All of the VF turbo's (Impreza fit) use an identical core, with only the compressor wheel varying. The exhaust wheel is part of the shaft, and can't be changed.

So, apart from porting the exhaust housing, and clipping/cutting back the blades, there's not much that can be done at that end.

It's pretty much the same for the TD series, like when you stick that dustbin lid TD06 cover, and wheel on

Now, if we switch to a Garrett core, there's a little more flexibility

Mark.

Andy.F

Mark

Do you find clipping 10/15/20 degrees from the exhaust wheel adds much lag to the spool up time ? How much does it raise the boost threshhold ?
I think I may need to consider this to control boost creep on the 20G.

I had an exhaust wheel 'clipped' 10 degrees on a hybrid I had on my cossie some time ago and was dissapointed with the results delayed spool up and no more power.

Maybe that was just a bad example ? Have you had measurable positive results with this approach ?

Andy

R19KET

Andy,

Sorry, but I can't give you direct comparisons, because it's only been done to a couple of turbo's, from new, and these were on mod'd engines.

One of them is an MD309, with ported WG, and we did some testing to set up the actuator, and it was running 2bar at the top end. Pretty brisk

But you're right, just like fitting a larger compressor wheel will increase lag, so will clipping the exhaust wheel.

I'm very interested to see just how the TD06 performs. Looking at the size of the wheel, one would expect it to be pretty laggy, but we'll see.

Mark.

dowser

He-he - quite a few people are waiting with baited breath on the results of this little test :-)

Andy.F

Crap result, 1.0 bar at 5000 rpm tailing to 0.8 at 6000

Wanted >>> All your useless 2nd hand TD05's - will pay scrap value

dowser

SSSsssshhhhh!

hunlimo

As the title says it. What BHP can I expect with the follownig mods

2.2L Stroker kit in a closed deck
8.8:1 compression ratio
vf 22 1.6-1.8 bar
GEMS (ALS)
Fmic
Mongoose 3" full decat
induction kit
uprated fuel pump

[Edited by hunlimo - 1/8/2003 11:11:53 AM]

john banks

VF22 compressor map. Sorry if that is a bit big

At manifold relative pressure of 1.6 bar it is running a PR I would esimate at about 2.7. Which is not too terrible at up to 70% efficiency, but they have a reputation for exploding.

However, at 1.8 bar even in the midrange you are on extremely dodgy ground even if the compressor wheel was strong since the PR would probably be about 2.9. That is really virtually at the top of the map and the speed is extremely high - can't tell from the graph as it is not clear, but the best I had, probably over 160000 RPM and possibly more like 180000-200000 RPM

Be warned that if you are running a top mount and the compressor blade shatters you will probably wreck your engine. A FMIC filters a bit better

Whilst the VF22 is considered the "Daddy" it will probably cause you problems quite soon.

[Edited by john banks - 1/8/2003 6:33:29 PM]

T-uk

JB,

try and keep up,he has a fmic .

you just worry about keeping that wee turbo on yours,in one piece.

[Edited by T-uk - 1/8/2003 6:39:42 PM]

john banks

You mean this one

[Edited by john banks - 1/8/2003 9:00:57 PM]

R19KET

This is a turbo sizing equation. It works out how much "air" an engine can consume, based on cubic capacity, RPM, and boost.

It is a rule of thumb, but gives a very good indication.

2122cc: 129.54CI x 7000 (rpm) x .5 div' 1728(converts to CFM)

= 262.4 CFM x 2.6 (1.6bar boost) = 682 CFM x 85%VE (volumetric efficiency)

580 CFM x .028314 (converts to Cubic metres) =16.42.

Now we look at the VF22 flow map, and see where 16.42 CM is.....

I've used 7000RPM as an example, but you would do this for all the rpm points, to see how suited a particular turbo is to an engine, and boost.

Edited to clarify that by "efficiency", I mean VE.

Mark.



[Edited by R19KET - 1/9/2003 1:54:05 AM]