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Discussion in 'Stage II Tech' started by norbs, Feb 5, 2012.
They haven't shown up in my box yet.
I got turbo and flow numbers. No cam specs.
Nevermind. Just found the attachment with the cam specs.
This is my 2nd option for cam, I will probably use the smaller cam as TK lobes scare me!
DURATION @ .050 INTAKE 234 ROCKER ARM RATIO
VALVE ADJ INTAKE .016 DURATION @ .050 EXHAUST
234 INTAKE 1.70
VALVE ADJ EXHAUST .020 LOBE LIFT INTAKE .4120
VALVE LIFT INTAKE .700 LOBE LIFT EXHAUST
VALVE LIFT EXHAUST .679 LOBE SEPARATION 112.0
DURATION .020 INTAKE C/L
TAPPET LIFT INTAKE 262
TAPPET LIFT EXHAUST 262
VALVE TIMING .050
VALVE OPEN INTAKE 7
VALVE OPEN EXHAUST 51
VALVE CLOSED INTAKE 47
VALVE CLOSED EXHAUST 3
Is the turbo plain journal or single or dual ball bearing?
What is the turbine housing radius? I need this along with the .60 a/r to get a better guess on the turbine nozzle size conversion.
The radius would be from the center of the turbine wheel to the middle of the scroll section close to the mounting flange. This measurement is tricky. You don't want to be too close to the mounting flange because that quickly increases the radius measurement. Post a pic of where you're making the measurement.
Its Dual BB. I can go out and measure the radius but just an estimate gonna be hard to measure exactly?
Just give me your best guess.
Looking very awesome so far.
OK. This is what I did. I found a nozzle diameter that gave max boost by just over 4500 rpm. That diameter was 2.1". Max boost was set to 41 psi.
The comparison graph is my Stage I at a max of 30 psi boost.
Norb's lines are the dark blue and green.
There are some problems that are showing in the numbers readout. The main one is the cylinder pressures at 4600 rpm and 40 psi boost! This is something you definitely are not going to want to do with pump gas. Even with racing gas! You are going to have to ramp the boost in much more carefully. I don't see a safe BMEP even for racing gas until 5600 rpm.
At 6000 rpm, compressor eff is at 58.8%.
What sort of intercooler are you going to use? I'm still calculating with 85% for the intercooler for your calcs.
I'm going to find a turbine nozzle size that will ramp in the boost in a fashion that will keep BMEP below a safe level.
Donnie, I think until we have some better nozzle numbers the accuracy is going to be way off. I measured the radius and I'm getting about 2.5" approx. I emailed u a pic. The inter cooler is a typical bar and plate. 5" deep x 30" across by approx 19" tall
Not sure what compresssor/turbine your planning on running but I found that boost won't come in as fast as you think with a large size turbo. My dyno log showing only 7.5 lbs boost at 4500, 25 lbs at 5800, and 35 at 6600. I think the turbine is not ideal for spool but performed well with regards to backpressure.
I gave you the wrong dimension, its 2.5" not 4" for the radius. I measured wrong. I now measured parallel to the center of the exhaust housing. the diameter of the flange port is 1.950" x 1.325 approx. I found this diagram to help me understand it. Its a dual scroll housing so I am not sure how that comes into your calcs.
Well your turbo seems bigger than mine, it could be compressor/turbine wheel size is larger in your set up.
Here's the latest. This one looks real good.
The intercooler eff was changed to 50%. A figure typically used for a quick acceleration air/air application. This parameter change made a world of difference to the output.
The turbine nozzle diameter I used was 2.0". I didn't use your radius figure. That gave me a nozzle dia of 1.8". I think that's too low.
The spoolup looked like what you're hoping for and the BMEP numbers came in at a peak just below 600. Still don't know how that's going to do with pump gas, but it was below the limit that I feel is a safe limit. For methanol, anyway.
The compressor eff looked good through the whole test. Maintained a steady 40 psi boost to the end with some still on reserve.
Looks like this will work real well. This program does not do a good job of simulating the spoolup characteristics, so Alan may be right about the spoolup. You may want to be prepared to spin this engine further than just 6,000 rpm.
I just noticed your new turbine information. I'll see if that makes a significant difference.
A .60 a/r and 2.5 radius gives me a nozzle dia. of 1.38. I'm not even going to try doing a calc with that nozzle size. It's just too small.
Donnie these turbos are rated for 1150 HP, I think you have to multiply something because its a dual scroll housing, are your calcs based on single scroll.? That particular housing i measured is 1.01 a.r I will be using a 1.28 a/r probably. I sent you the coy of the turbine map too.
That does change things. I thought I saw someplace that you were going to use a .60 a/r. I'll see how these new a/r numbers work out.
Another thing to consider. When you see a split housing labeled as a 1.01 or anything else, that will mean the a/r is less due to the area that the dividing wall itself takes up.
I will make sure I'm using split housing. Although, like I've already stated, this program does not simulate spool up very accurately, so I'd just ignore that area of the graph, anyway. You won't really know until you actually run the engine.
That is true Donnie, the compressor housing is .60 a/r in case you ask. I had the turbo on my 3.8 with non stage heads and it spooled about the same as a 70 3 bolt with .81 ar in comparison. I could easy make 15 psi boost #3800 rpm-4000 rpm. Here is some more data.
Turbo PNCHRA PNInd Whl Dia(mm)Exd Whl Dia(mm)TrimA/RWhl Dia(mm)TrimA/R
800269-2 451888-44 75.80 102.30 55 0.60 82.00 84 0.00