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March 26, 2007
Swap Meet Water Pump
At the Thompson Speedway swap meet last fall, I picked up a Stewart 22203 water pump.
Chevrolet Small Block
Short Stage 2 - 22203
* Chevrolet Small Block - Short
* 1955-68 Passenger Cars
* 1955-72 Light Trucks
* 1955-70 Corvette
* 5.625" Length
* 3/4" Bearing
* 3/4" Shaft
* Special Severe Duty Pump
* High Flow Pump
* Cast Aluminum Finish
* High flow impeller
* Equal flow to left and right cylinder heads
* High flow and pressure
* 356-T6 heat treated aluminum specially ribbed casting
* Precision ground fan hub with dual bolt pattern
* Zinc-plated rear cover and bolts
* Extra rigid cam stop with 3/8" adjustment screw for small block models
* Two 1/2" NPT auxiliary inlets
* Extra material on small block Chevrolet models for installing external lines to center of the cylinder heads
Posted by Z28tt at 4:36 PM
March 8, 2007
Turbocharger Specs & Calcs
Turbonetics T04E
O Trim Turbine Wheel (appx 61.7 Trim)
EXDUCER DIA.: 2.296" (58.3mm)
MAJOR DIA.: 2.922" (74.2mm)
40 Trim Compressor Wheel
INDUCER DIA.: 1.870" (47.5mm)
MAJOR DIA.: 2.950" (74.9mm)
INLET DIA.: 3.000" (76.2mm)
OUTLET DIA.: 2.000" (50.8mm)
TrimCompressor = (Inducer Dia) ^2 / (Major Dia) ^2 * (100)
TrimTurbine = (Exducer Dia) ^2 / (Major Dia) ^2 * (100)
Larger trim supports more airflow
.58 A/R
Map:
To read the chart, first calculate the airflow.
Cubic Inch Displacement (CID) = 399
Volumetric Efficiency (VolE) = 90% (estimated)
RPM = 6000
Boost Pressure = 5 psig, 14.7 psig, 20 psig
CFM = RPM * CID * VolE / (1728 in^3 per ft * 2 revolutions per cycle)
CFM = 6000*399*.90/3456 = 623 cfm
Since the Turbonetics maps are in their corrected lb/min, we have to convert CFM to lb/min, and then apply a correction to match their inlet temperature & pressure.
Ideal Gas Law is PV=nRT, or switched around to lbs is n (lbs/min) = PV/(RT)
P is Absolute Pressure, psia, so add 14.7 to your boost pressure
5 + 14.7 = 19.7 psia
V is Volume, or CFM = 623 cfm
R=10.73 (universal gas constant for air in these calcs)
T=Temp, in Rankine (add 460 to DegF), 110 degF + 460 = 570 degR
19.7 psia * 623 cfm * 29 / (10.73 * 570 degR) = 58.2 lb/min
Since we have 2 turbos, also divide by two.
Lb/min@5psi = 29.1 lb/min
Lb/min@14.7psi = 86.8 / 2 = 43.4 lb/min
Pressure ratio = (boost + atmosphere) / atmosphere
PR5 = (5+14.7)/14.7 = 1.34
PR14.7 = 2
Draw a line from the lb/min on the X axis going up, and the pressure ratio on the Y axis going across. Where they intersect is the turbochargers efficiency (and speed). At 5 psi, you have a PR of 1.34, and 29.1 lb/min. This is to the lower right of the graph, and not very efficient (on the 69,800 rpm line). At 14.7 psi boost, you are at a PR of 2 and 43.4 lb/min, well to the right of the map. This shows that the engine is producing much more flow than the compressor can pump, so it won't be very efficient. Back when these turbos were chosen, they were designed around 5500 rpm 305 (436 cfm) and 8 psi boost (PR 1.55), which has 22.7 lb/min airflow, and would be right around 72% efficiency. Upgrading to a 60 Trim compressor would put me at 70% at 5 psi, and 73% at 14.7 psi boost.
What I need to do for now is short shift it. By reducing the RPM by a third to 4000, the airflow also gets cut by a third. 5psi=19.5 lb/min & 65% efficiency and 14.7psi=29 lb/min & 73% efficiency.
Posted by Z28tt at 5:29 PM
Video & sound from the dyno runs
I spent 4 hours cutting down 20 minutes of footage to 4 minutes last night. It's best if you watch google videos in the original size (little icon on the bottom right of the movie window).
http://video.google.com/videoplay?docid=4282173294346413965&hl=en
This is just the first run at 4 psi and some steady state tuning off the street - you can really hear when the dyno loads the engine near the end... I'll get the other runs done tonight when we turn up the boost.
I stripped the sound out of the dyno video for a 750 kb mp3 clip:
http://www.skulte.com/video/bristoldyno_sound.mp3
Be sure to put this in your ipod, and crank up the stereo on the daily driver!
Full engine details at http://www.skulte.com/z28tt/archives/2004/05/engine_specs.html
Posted by Z28tt at 12:37 PM
March 1, 2007
17 more dyno runs!
Jonathan at BristolDyno.com was great, and really helped us get many runs in just 3 hours tonight. The directory with all the Dynojet runs (and a free viewer from dynojets website) is at:
http://www.bristoldyno.com/vehicles/Chevrolet/Camaro/Skulte_Andris/
1st run was right as-is off the street - mostly under 4 psi - 455 hp & 445 tq
Not logged, but we did some steady state with the dyno brake (Dynojet 240 w/ a brake). I was overpowering it at low rpm, no boost, and it would only hold it for about a minute before the brake would overheat & start slipping. I think there's some good video of my cast iron manifolds glowing cherry red! (Got to get the EGT's in there) I'd like to play more with the steady state & ignition timing next time, but it's not just not beefy enough for more than a minute or two at a time it seems.
2nd was a bit warmer, no changes - 459hp/454 tq
3rd run I added 2 degrees of timing - 33 at 0, 31@ 2 psi and 29 @ 5 psi - picked up another 20 hp (480/473), right around 5600 rpms
4-7 I was trying to richen things up (losing battle, trying to get it down to 12.0,from 12.5) no real increase (478-487hp and 467-481 tq)
8 I tried my ghetto boost controller, which spiked to 17 psi @ 3500 rpms! Jon let off immediately... That was 407hp @ 579 tq at 3500, and a 12.7 air/fuel
9 something happened (it's in my notes), and jon let off. Maybe an intake pipe blew off...
10 I was full open on the ghetto boost controller (now known as the GBC), and had 1.2 psi more boost (4.66 vs 3.5) up to 5500. 485/506
11 More of the same boost, playing with fuel
12 Closed up the GBC one more turn, for a whopping 6 psi boost! :) 520/539
13 Closed GBC one more turn - 8 psi baby! 535/577 - Even though the air fuel wasn't too horrible (12.7 & steady), Mike Rizzi (a longtime friend that drove up from NY) noticed my fuel pressure started dropping from 4000 @ 60-ish to 30 psi! Eeek! Air/fuel still showed good, so compensating with more pulsewidth works for now.
14 Closed GBC to 1/2 turn - 11.5 psi, but let off at 4000, Very choppy run w/ 40 hp peaks & dips, I believe it's the dropping fuel pressure not giving good atomization at that boost level). 470/622 Thought it might be spark, but it's has the Accel 300+ CDI, and the plugs are gapped at .035.
15 Opened GBC a little, 7.5 psi to 4500 & dropping to 6@5500 540/578
16 Tweaked the GBC, 8.5psi to 4200, drops to 4.3@6000, and added the K&N filters & hose (the others were just open turbo) - 510/610. More power to 4600, but then drops off compared to #15, but I think that's the 1/2 psi boost difference. I need something more repeatable!
17 Closed off the GBC, for zero wastegate action. Blew apart the line from the IC to the TB @ 18 psi. 462/638@3800
Jonathan mentioned his boost measurement was reading a bit low. I'm thinking about 2 psi low compared to the screen in CALMAP, but I didn't log anything. I learned that 2 degrees of timing is worth 20 hp. I'd like to try more later to see where it plateaus, once I get a second Walbro in there. The fuel pump just can't keep up at more than 7 or 8 psi boost (how much are the stock 3/8" hard lines good for?). I also need to bolt together my intake piping with tabs & aluminum bars so they don't keep blowing apart at 12psi+. I need to wash the K&N's, and maybe fab an air box, get air from the hood, and run aluminum mandrel bent pipe instead of 3" flex hose. I also need bigger injectors than the 55lb/hr Siemens in there now.
The GBC - It's a needle valve with a .040 bleeder port before it, then tees for the wastegates after the needle valve. The valve has 4 turns, but only really seems to modulate from 3/8 turn to 5/8 turn from closed, so possibly something a bit more sensitive would work, or a larger sized bleeder.
A big thanks to Jonathan for staying late, Mike Cheney, Mike Rizzi, and John Santos for helping out, and keeping a watchful eye (various popped off pipes, wideband sensors flying, etc!), and my dad for videotaping in HD (I'll get that converted and online soon).
In short, I picked up 65hp & 34tq, at the same boost, by the replacing the SLP catback with the boom tubes & adding 2 degrees of timing The TQ curve is almost identical to 4700 rpm, then the old SLP catback TQ starts dropping quite a bit (40 ft-lbs low @5500 rpm). It's at 480/480 rear wheel & 5 psi on the street as I rolled out. I think I'm going to see if I can get some 10, 14, and 18 psi wastegate springs to have on hand (and not use the GBC) for next time. Turn it up, baby!
Posted by Z28tt at 8:04 PM