Custom 3.2 turbo kit, part2

YermanCars · 01:20 PM

Now as many of you know, I will be taking on a winter project.
After 9 months of extensive reaseach and talking to the HPjunkies, I have come to the decision that I will be fabing my own custom turbo kit for my 3.2. Now to clear things up a bit, I am basicly doing a low boost economy set up. That means no intercooler, I love the sleeper look of my car right now and don't want a tail on it. Instead of an Intercooler I wll be runing a Co2 bottle kit, which does the job just as well, if not better. For my turbo I will be running a TO4B18.
A/R on exhaust side is 1.15 and compressor side is .60 so it obviously can make enough boost for the .5 bar i want to run.
Now as far as pluming and piping go, i have the blue print done, , a local tuner shop is getting all my pluming and piping cut and figured out. Now I have two big concerns, First being the waste gate, the economy kit calls for 40mm tial waste gate, I would like to run a 38mm tial waste gate instead($200 cheaper then the 40mm) and since the 38mm waste gate is fully adjustible up to 1 bar I see no problem in this. Any objections?
Second concern would be my chip, I can have someone map me out a new chip,but I would have to know the exact A/F ratios, Can anyone help me out on that?
Thats about it, I will keep everyone posted and Will try to document it.
Thanks for all the help, You guys are Awsome

Tony

rfng · 10-07-2003, 05:19 AM

Your A/R is too large for 7 psi.

YermanCars · 10-07-2003, 05:21 AM

what Turbo would you recommend

emcon5 · emcon5's Garage

Juan has his old setup for sale:
3.2 Turbo conversion Hi-Performance parts

Tom

beepbeep · 05:54 AM

Quote:

Originally posted by rfng
Your A/R is too large for 7 psi.

Errr...what are you talking about? Are you talking about Compression Ratio (C/R) or turbo A/R?

A/R is just a ratio of turbine wheel diameter to size of the nozzle driving it. A turbo pumping 7 psi of boost into 2-liter engine will pump substantially less air than one boosting same pressure into 4-liter engine. Also, smaller A/R will produce less lag but also introduce more backpressure...

With other words, different A/R's on same turbo will mostly affect response and engine characteristics (boost treshold etc.) ... but he will still be able to boost over 7 psi whenever he wants.

Tony:
People tend to use pretty big wastegate diameters, but it's mostly unnecessary. I'm pretty sure 38mm is more than enough.

I'll try to explain this with my own example:

Once upon the time one of my air-injector plugs blew out on the highway. Car sounded like a moped and it took forever to build some boost, despite having hole that is 10mm in diameter, on only one cylinder.

1fastredsc · 10-07-2003, 05:55 AM

I looked through turbonetics compressor maps, and the t04b compressor maps (there's 3 of them) look like they'll do you justice. 1.14 AR turbine might be a little over doing it. You'll have lag up the ying yang and plus with a half bar you don't need it that big.

1fastredsc · 10-07-2003, 06:03 AM

Beep, i thought the AR ratio would affect the exhaust flow after boost is on as well therefore making the AR ratio important on boost (7psi) as well. If you think about it you said that backpressure is created with too small a AR, therefore you over heat the heads and creat detonation. With half a bar, his exhaust flow will only increase by 50% (if i remember right it's linear) and therefore the need for a turbine that large isn't present. If i'm wrong please enlighten me.

YermanCars · 07:28 AM

what about running it at .6 bar, the reason I have this turbo is becausemy brother bought it for his car and didnt need any more so he gave it to me, or else I would have to buy the Gerrett T04 60-1. What website are you finding the Stats

beepbeep · 08:43 AM

Quote:

Originally posted by 1fastredsc
Beep, i thought the AR ratio would affect the exhaust flow after boost is on as well therefore making the AR ratio important on boost (7psi) as well. If you think about it you said that backpressure is created with too small a AR, therefore you over heat the heads and creat detonation. With half a bar, his exhaust flow will only increase by 50% (if i remember right it's linear) and therefore the need for a turbine that large isn't present. If i'm wrong please enlighten me.

It's a common missunderstanding that backpressure somehow makes car less knock-proof. It has mostly nothing to do with knock (especially with watercooled engines where head never get's "overheated" as it's moderated by water) but it can create high EGT's which are harmfull for turbo.

It's also very common practice with manufacturers of "family" -turbocharged cars to fit slightly smaller turbochargers on their engines. Such combo provides little lag and good response in midrange (as soccer-moms don't bother to downshift anyway), good torque and overall driveability.
Unfortunatelly, those turbos usually run out of puff at higher revs and just blow hot air around so ECU is often programmed to taper boost higher up in rev-register. Also, EGT are high so headers are often cast in some nickel-alloy to prevent cracking.

Typical examples of such engines are ubiquous VW-group 150hp 1.8T engine, SAAB B234 light pressure turbo etc.

It's a question of what you want to achieve...if max power is desired, you don't mind revving extra to come on boost and are afraid of high EGT then bigger AR and/or turbo is nice...

1fastredsc · 10-07-2003, 08:10 AM

hmmm, that's interesting, i had a different take on things but i guess i'm wrong. Either way, the goal should probably be full boost through the later 2/3 of your rpm. If you can find a turbine that'll achieve that then your in business. Your AR sounds like it's a bit too much, more like the later 1/3 of your rpm. Use RFNG's experience as a base, the turbo he uses is a garret hybrid that he claims to achieve good boost response with while retaining full boost up to redline. Then push the AR ratio up a smudge since he designed it with a 3.0 in mind and you should be a happy camper.

1fastredsc · 10-07-2003, 08:18 AM

www.turbonetics.com, they have compressor maps on the site. Also you may want to buy a good book calculating cfm so you can figure out at x amount of rpm with y boost creates z cfm. This way the maps will makes sense to you.

juan ruiz · juan ruiz's Garage

TO4B.58

beepbeep · 10-07-2003, 09:08 AM

Dyno of 2-liter engine fitted to Garrett GT37 turbo with large A/R:

As you can see, boost comes online pretty late but there is no problem in boosting a lot...

Also, 450hp from 2-liters mill with huge turbo shouldn't be possible according to "you cannot boost with huge A/R " -wisdom.

YermanCars · 10-07-2003, 10:12 AM

anyone know where to buy one Ebay doesn't have any? and exacaly what is it proper name for search purpose

1fastredsc · 10-07-2003, 12:25 PM

No one said that you couldn't boost with a small AR, the point is trying to find the sweet spot where you have minimal lag and still have good boost to redline. Anybody can hook up a massive turbine to the motor then wind it out until there's enough flow to create boost pressure. But at that point you've waited quite awhile and then the car knocks your head off (not that that's bad

). But seriously, if experiment permits, shouldn't you shoot for like a 2.5k to 3k spool with a 7.5k rpm like that one you posted. It seems if you have a turbo like the garrett gt series it should be spooling much earlier. That boost graph looks like one from one of those high output civic motors, the difference though, is that they have an 8k to 9k redline.

beepbeep · 02:31 PM

Dyno graph on picture comes from Nissan 200SX (i believe it's even less than 2L liter...1.8L as far as i remember) with very hot cams, and lorry-style non-BB GT37 (a turbo bigger than KKK K27, mind you).

Even with that lawnmower engine, wild cams and huuuge GT37 turbo it boosts over 0.5 bar from 3500 RPM onwards. Those GT-turbos are simply amazing! My 930 didn't get on boost at all under 2800 RPM, and it had 3.3 liters.

Our engine is 2.3L and is getting bolted onto GT40 (also non-BB, costs too much $$) with smallest possible A/R (0.58) so i'm pretty confident we'll see at least 0.5 bar of boost before 4000 RPM.

I'm a huge believer in those new turbochargers. They are essentially like turbins, and there has been tremendeous advance in turbine-shaping in last 10-15 years, mostly thanks to computer simulation. TO4B is pretty good but not the "latest and greatest Pentium IV" of turbochargers...more like "Pentium Pro". K27 is 486 and 3DLZ is something bordering on 8068...

1fastredsc · 10-07-2003, 02:23 PM

Good, i was hoping you weren't going to be that top end nuts with that saab motor. It's funny how into this i got when my dad decided to make his 951 a monster. BTW, his turbo is finally coming in, which means he can match something to that evil 2.7 he built. K27 #8 turbine housing with a t04 compressor, i can't remember which one, but i do remember that it's got a 3 inch inlet on the compressor

.

YermanCars · 10-07-2003, 02:30 PM

Hey guys could I take the T04b18 and Change it to a T04B .58 if so How?

beepbeep · 10-07-2003, 02:35 PM

Quote:

Originally posted by 1fastredsc
but i do remember that it's got a 3 inch inlet on the compressor .

Hmm...GT40 has 4-inch inlet and 4-inch outlet

(well inlet is probably that big just beacuse of "ported shroud" mumbo-jumbo thingie...)

feelyx · 10-07-2003, 02:39 PM

Here is a turbo plotting program that is pretty accurate..
http://www.turbofast.com.au/turbomap.html
Tim in Sac