Cascade Crew

Twilightoptics

$30.00

Even if it wont work for my application... it's a steal! Garret/AiReseach/Mercedes(I think). Doesn't look like it was leakin oil, and there is NO shaft play! Verified by the tubro geek at work! Will clean it up this week and make it look like NEW! :O)

Dewey316 · Posted: Sat Apr 05, 2008 6:32 pm Post subject:

Pictures no work. Sad

What model is the turbo?

Twilightoptics · Posted: Sat Apr 05, 2008 6:37 pm Post subject:

hehe not sure. Pictures should work now. Had the wrong tag on em.

Twilightoptics · Posted: Sat Apr 05, 2008 6:38 pm Post subject:

http://cgi.ebay.com/ebaymotors/Garrett-Airesearch-TA0314-Turbo-85-Mercedes-300-SDL_W0QQcmdZViewItemQQcategoryZ33742QQihZ006QQitemZ160226269832QQrdZ1QQsspagenameZWDVW

Hehe found one on eBay. With compressor map. Now need to compare the maps!

BigDaddyVu · Posted: Sat Apr 05, 2008 6:40 pm Post subject:

whats the A/R???

Dewey316 · Posted: Sat Apr 05, 2008 6:40 pm Post subject:

It may be a hair on the small side for your motor, I wanted to think that we were in the about the 2lbs/min of airflow @ 5k rpm on the 2.8, I would have to rerun the numbers though.

Dewey316 · Posted: Sat Apr 05, 2008 6:41 pm Post subject:

BigDaddyVu · Posted: Sat Apr 05, 2008 6:43 pm Post subject:

my t-70 a/r .91 is small for a 5.7 liter buy another one and run twins it will spool up faster than mine.

Twilightoptics · Posted: Sat Apr 05, 2008 6:55 pm Post subject:

This one should be perfect. These are the numbers you came up with on the other map's John. On the WRX turbos they crossed on the right side of the central efficiency ring... at about 70% or a hair less.

1.8 Pressure Ratio/ .15m^3/s

Thise guy is just about dead nuts. According to the auction it was on a 3.0L Diesel.

10lb/min=144.72cfm
2.8L @ 4900RPM:
80%VE=196 = 13.8lb/min
100%VE=245 = 16.9lbs/min

Just have to figure out how much boost this thing does then control it!

Dewey316 · Posted: Sat Apr 05, 2008 7:03 pm Post subject:

by those numbers you are right where you want to be for that part of it. We need to map out the surge line, but it looks like it has a pretty forgiving surge line.

Vu,

This isn't going on a 350, its going on a 2.8L.

Twilightoptics · Posted: Sat Apr 05, 2008 7:04 pm Post subject:

How do you map the surge line? This C-Map has the line on it. The Audi and WRX maps don't have it at all.

And when the map "maps" airflow... it is plotting the N/A Airflow... vs the PSI I want to run... right?

Dewey316 · Posted: Sat Apr 05, 2008 7:29 pm Post subject:

the other maps do have it, it probably just isn't labled. THe left had line is always the surge limit.

Basicly if you create too much boost, without enough flow, you hit the surge line, if you run a BOV you will probably be fine, mapping out it, is a bit of dark voodoo magic. You sort of figure out about where the turbo will start spooling and creating boost, and ramp up to you boost level, and make sure that it doesn't cross the surge line.

The other points you cross the surge line at, are when you let off the throttle, because your airflow goes to almost nothing, but the turbo is still creating boost, that is what the BOV will prevent though.

So basicly, for this, we want to see what RPM your airflow need is .75lbs/min of airflow, because that is the point where your boost level corsses the surge line. So long as the turbo doesn't spool up to full boost by that RPM, then everything is golden.

Twilightoptics · Posted: Sat Apr 05, 2008 8:51 pm Post subject:

The other maps are just the islands, no line.

Think we should be fine then with the surge bit.

Don't you kind of have to run a BOV just because the nature of the positive pressure and closing the throttle? Or is there a lower PSI one could run without one?

Dewey316 · Posted: Sat Apr 05, 2008 9:05 pm Post subject:

I would suggest running one not matter what. I would actualy probably run a recurculation valve, that will help with keeping the turbo spooled on shifts, and getting right back into boost on shifts.

Something like this. You plumb it in, and then recurulate that air back just in front of the turbo inlet. I have that one at my house for the audi, if you want to look at it, or use it for mocking stuff up, just let me know.

http://www.034motorsport.com/product_info.php?cPath=21_98&products_id=781

--John

BigDaddyVu · Posted: Sat Apr 05, 2008 11:12 pm Post subject:

With out a blow off valve it could blow couplers or preventing your butter flies to close quickly and cause it to lean out. what type of pistons are you gonna run? i'd either use the stock or forged flat top pistons with a ring end gap of .060 on the top and .050 second ring. marty runs stock flat tops with lose ring gaps on his t/a

Twilightoptics · Posted: Sun Apr 06, 2008 7:51 am Post subject:

This is a bone stock 1989 Camaro 2.8L

chevymad · Posted: Sun Apr 06, 2008 11:46 am Post subject:

Got a question. I was reading about diesel exhaust brakes awhile back, and discovered something I hadnt heard about before. The limit to the amount of braking an exhaust brake will do is the rating of the exhaust valve springs. Stock springs are limited to 15psi on a cummins, but with a change you can go to 30psi of back pressure. Seems the pressure pushes the exhaust valves open then they collide with the piston. You take the area of the back of the valve and multiply it by the psi and find out how many pounds you're removing from the spring seat pressure.

Now isnt this the same with a turbo? And even worse its on the larger intake valves so more area. How heavy are the stock 2.8 springs? I'd think valve float will come on pretty early with 15psi behind them.

Xophertony · Posted: Sun Apr 06, 2008 2:24 pm Post subject:

at least a 2.8L is a non interference engine, so no piston to valve contact. Smile

Twilightoptics · Posted: Sun Apr 06, 2008 2:48 pm Post subject:

How would one measure pressure on the exhaust side?

I've never heard anyone do this before?

If you're creating 14PSI on the intake side... that may not necessarily mean it's 14PSI on the exhaust side?

Aren't the fins different to create a kind of ratio effect?

Interesting point B.

I have the spare set of 2.8 heads Travis gave me. I might just bring one into work and check some of the exhaust springs.

chevymad · Posted: Sun Apr 06, 2008 3:01 pm Post subject:

The exhaust brake setup was an example.. You are making the pressure on the intake side.. so you have 14psi pushing against the area of hte back of the intake valve.. trying to open it when its seated. If the valve is allready close to floating it'll pop open sooner.