Z28tt Project

Autometer Gauge Cluster

Some folks have asked to see pictures of the guage cluster I fabricated with Autometer Ultralite gauges. This completely replaces the factory Camaro gauge cluster and bezel. It's a tight fit, but I managed to squeeze in a 5" tach and speedo, as well as 2" oil pressure, fuel level, and battery voltage gauges, as well as LED turn signal and high beam indicators.

More pictures at:
http://www.skulte.com/gallery/view_album.php?set_albumName=Gauge-Cluster

tire grip

I've made a spreadsheet to try a few different "what if" scenarios (adjusting corner weights, Center of gravity, downforce, and power), and it all hinges on getting a good ballpark coefficient of friction for the tire. I know it's impossible for me to get an accurate model due to all the variables that can change (i.e. I don't have $20k to have Calspan model my Kumhos!) but I'd like to get a ballpark curve so I can at least see what a change will do.

So far from Herb Adams book, he's got a table on page 2 with traction vs weight:
0:0
500:275 (coef of friction is 1.81)
700:500 (1.4)
1000:1000 (1)
1280:1500 (.85)
1500:1900(.79)

The polynomial I got from an excel trendline is:
-.00028*X^2+1.261*X+73

Milliken has a few charts on p78 and 79 of slip angle vs lateral force that has several curves based on vertical load for the 275 goodyear eagle ZR, a 27x14.5 Champ car rear tire, and a 25x9-13 F1 front tire. I'll get the numbers from that in a few nights when I have a chance.

The goal of all this is to figure out that 300 lbs of downforce will give me an extra 200 lbs of grip, which will let me corner at .2 more g's, which gives 4 mph faster exit speed, and saves 3 seconds per lap (purely made up numbers, but should be ballpark). Or see that ditching the 150 lbs of turbo gear on the nose and losing 250 hp will not slow me down.

Accel 300+ ignition box issues

A while back, the Camaro wouldn't start, and I traced it down to no spark. The fuse for the 300+ was blown. I replaced the fuse, and it blew again as soon as the car cranked. There were no shorts in the wires going to the coil, and the Camaro ran with the 300+ bypassed on the factory HEI ignition. I then tested out the 300+ by replacing the fuse, and grounding the white trigger which usually causes it to fire the coil, and as soon as the trigger wire grounded, the fuse blew. I called MrGasket/Accel (216.688.8300), who suggested I send the box back to get repaired at their Jacobs Testing Facility in Carson City, NV. Not having heard back in a month, I've got to call them (775.882.6600, press 0 for operator). We'll see!

Watkins Glen line update

Just got back from a 2 day track event at Watkins Glen with the Schattenbaum region PCA. The Z28tt broke the spare T56 on the 2nd lap (locked in reverse after I came into the pits, with gears 1-6 binding the transmission). I couldn't feel the synchro engage in R, but it did in 1 through 6, so we decided the reverse gear clutch fork or roll pin had broken. Since there were 2 track days, Mark Frouhar helped remove the tailshaft housing to get at the reverse gear cluster, and hopefully disengage the synchro and get the forward gears back. As soon as I got the tailshaft housing off, bits of bearing fell out, and ended my chances. Instead, I now had 2 days to instruct and get ride alongs with other folks. After a track walk (3.5 miles!), you could really feel how the concrete patches don't have nearly the same grip as asphalt. Another interesting thing was that all the corners are banked more towards the inside and banking tapers off (3 lines) towards the outside of the track. This makes for some interesting lines, staying more inside than usual.

Turn 1 - turn in earlier than expected to bring car down to the apex, and track out onto the rumble strips.

Turn 5 (sweeper after bus stup) - enter 1/2-2/3's over to the left, bring is steadily down, and get on the throttle as soon as you know you'll make the apex.

Turn 6 (going into laces) - Don't be fooled by the painted line moving left - the pavement stays straight. Some folks were turning in very early and leaving a good 5-8 feet on the right side of the car. The banking is steeper on the inside line, and lets you get a faster exit speed.

Turn 7 (toe of the boot) - Enter normally, and bring it down immediately below the concrete. Get on throttle, and cross concrete on the way out and out.

Turn 9 (off camber left) - Turn in right after crest of hill.

Turn 10 - Slight brake/lift depending on HP. Not much need to slow down at all.

Intercooler Specs

The intercooler core I chose was the Spearco 2-182. The charge area is 3.5" x 15.6" (54.6 in^2) and the ambient air side is 15.6" x 20" (312 in^2) and is rated at 1500 cfm at a 1.5 psi pressure drop. I fabricated sheetmetal plenums on either side with a 3" inlet and outlet.

Fab link

Picture Gallery

I'm waiting for Turbonetics/Spearco to email the intercooler flow chart. (8/14/07)

LRP Wear Measurements

Summary: Tire wear measurements were inconsistent, but the V710's grip and wear well. They are all starting to show separation at the butt splice in the center of the tread, after 1 day at Watkins Glen and 1 day at Limerock. Front brake pad wear was about .050-.075" at the front, and inconsistent in the rear. If the front pads wear about .070" per day, have .190" backing plates, are .800" total thickness new (.610" pad material), and wear stupid fast once pad material is down to .190", that gives 6 track days per $100 front pads, or $17/day.

I went through about 27 gallons of gas in about 50-75 laps, but something odd is going on, causing the Camaro to run very rich.

]]> Tires: New Kumho V710's at Watkins Glen, 275-40-17's in the front and 315-35-17's in the rear.
Tread depth at wear holes: Inside-Groove-Middle-Outside
#1 RF .140 .132 .132 .132 (to be run on left front)
#2 RR .130 .126 .132 .135 (to be run on left rear)
#3 LF .110 .130 .130 .110 (to be run on right front)
#4 LR .130 .128 .132 .125 (to be run on right rear)

After LRP:
#1 LF .135 .130 .125 .120 (about .005 wear)
#2 LR .140 .130 .125 .125 (inconsistent)
#3 RF .125 .114 .125 .110 (inconsistent)
#4 RR .148 .140 .142 .130 (inconsistent)

I guess this means the tires didn't really wear that much. I'll see what it's like after another 2 day event.

Rear Pads
Rear before WGI:
PFC 90's 0413.90.13.04
.496, .471, .448, .405
Drivers Rotor .780"
Pass Rotor .785

Before LRP: drivers outer - .400" including backing plate
pass outer - .350" including backing plate
After: drivers outer - .350"
drivers inner .460R .480F
pass outer - .380"
pass inner .430R .435F
Not much wear, and inconsistent with an estimated first measurement. Inside pad has a .200" thick backing plate and outside pad has a .160" thick backing plate.

Front:
Wilwood Polymatrix B - 15B-5939K (7420 w/ bridge bolt)
C5 Rotors, both at 1.260 after LRP.

After WGI Front Pad, then after LRP (changed from left to right to reverse taper) :
#1 DriversOuter: .690 at front and .602 at rear, .635 middle top and bottom
After LRP: .575F .540R .550T .570B
#2 DriversInner: .638 front and .620 rear, .609 middle top and .640 middle bottom
After LRP: .597F .584R .604T .600B
#3 Pass Inner:.722 front and .625 rear, .673 middle top and bottom
After LRP: .620F .620R .625T .635B
#4 PassOuter: .638 front and .622 rear, .626 top middle and .642 bottom middle
After LRP: .585F .535R .550T .570B
The taper wore off nicely, and pads are much flatter. I think this is due to being a bit more gentle on the brakes, and doing a more thorough job bedding in the pads to the new rotor. The pad wear was about .050-.075" once flat.

50# 17x9.5 C5 wheel (speedline) with 275-40-17 Kumho ECSTA Supra

Limerock Park with Cart-CT

Got to bed at 1am with the trailer loaded Wednesday night (three 1am
nights in a row, getting ready), and up at 5:30am to be ready to go
when Justin arrived (local CTFBA buddy). Fueled up the Durango and two 5
gallon fuel jugs, and hit the road. Arrived at the track with tons of
parking left, and saved a spot for Mark. Only a 70 car cap to
registration, so it wasn't too crowded. Rolled the Camaro off the
trailer, registered (already done from the internet, so you just claim
you packet and get a t-shirt, very quick) and went through tech. There
was a novice track walk at 8am which would have been cool, to actually
see all the little details of the track up close. I've never done that
for a road course. We had our drivers meeting at 9am since everyone
was waiting for Mark to arrive from NYC (just kidding!), and probably
had the first car off at 9:45 (took forever for the workers to get
situated). They had everyone split into 3 groups - A (fastest) to C.

]]> Mark and I went out in the A group with some fast Evo's (running
around a minute flat) and stupidly, they put novices with fast cars in
A group as well. We had passing on the front and no-name straights,
with no point by's necessary, but it was a good courtesy. Limerock
castrated no-name straight by laying out cones squeezing the last 200
feet to one lane, to keep folks from making a late pass. Every lap
there were trains stuck behind the six novices in GroupA, and because
of the small passing zone in the back, you only had room to get by 2
cars. Consequently, there were constant trains of 4+ cars with
everyone stuck behind a novice. You'd catch up to a train by the
esses, 2 folks would pass at noname, you're stuck behind for the
uphill, west bend, and downhill and then you'd pass right after the
downhill, only to catch up to the next train by the esses again. The
novices were great with point by's and not drag racing down the
straight, so the instructors did a great job keeping everyone
courteous (except for one guy, later...). Justin timed me at 1.12's
for the first 6 or so laps and by that point the novices were starting
to get the hang of things, and I was down to 1.06's (had a fun time
just following Kyle through traffic with his even faster Evo, enjoying
the smell of race gas in the morning!). Finally got one clean lap -
1.03! Started out the session with the Kumho V710's at 30 psi cold,
and at the end, they were LF:41, RF: 38, RR 36, LR 37 psi. Dropped
them back down to 30R and 32F.

Tire Temps (outer-middle-inner), in the pits a few minutes later (thanks Justin!):
LF 173-170-166
RF 155-150-159
RR 130 138 128
LR 139 146 136
You can see how the pressure got too high and the center of the tires
was hotter. 9" rear was at 148 degrees.

After they ran through the run groups, it was open track for the day.
It's my first time running that format, and I loved it! The Camaro was
running well, and I didn't think to top off the gas, figuring one
session wouldn't burn that much fuel. Wrong - 4 laps in, the fuel
pressure was dropping in the corners (gauge read half tank). Back into
the pits to dump in 5 gallons, another 4 laps, and the stumble was
back. I need to look at the DFI6 fuel trim tables because I was
pegging out the wideband and power felt down - maybe I've got a funky
setting for IAT or CLT tables that goes to a full rich safety mode
.

Pit in, add another 5 gallons, and good to go (for another 5-10 laps).
By this point, the track was pretty open, and you'd only get stuck
once a lap behind a slower car. I can understand not allowing passing
in more places, but the uphill would be a perfectly safe zone, with
lots of room before West Bend. I'd usually hang back after West Bend
to get a run through the downhill corner, late apex, and go right by
on the inside (as long as there wasn't a train, and other cars in
front, passing on the right). Then I caught up to a shiny red Ferarri.
And stayed on his bumper through the esses (didn't want to dog him too
badly, since he had the N sticker on the back for Novice, and I
couldn't afford to fix his car if he did a panic stop and I drove into
the back). We got to no-name straight, and he's drag racing me? WTF?
Dog him through the uphill, west bend, and downhill, go to the inside
to pass, get next to him, and drag racing again. Huh? Pull in behind
again, and put put through the esses. By this point, I'm waving my
hand out the window, trying to get the flagger's attention for a blue
flag, but no luck. He's WOT on no-name, uses the full track to
eliminate the passing zone on the right, and now it's impossible to
pull a pass if the passee doesn't lift. Yes - even in the Z28tt. Slow
down to what felt like 40 for the uphill section, and now I really
hang back for the downhill, since he likes to brake a lot for the
downhill corner. I get a run on him, go (slowly) past as he's drag
racing, and get in front before the brake zone this time. He's no
where to be seen by the time I get to noname. Had a chat with him
(nice older gentleman), and it seems he doesn't understant the point
of track days. I tried to explain that he's going very slow through
the corners, and there are cars with less horsepower that get stuck
behind him in the corners, and don't have the HP to pass on the
straights. He said he didn't want to beat on the car in the corners,
which is why he was driving slow, but he likes going fast on the
straights. Maybe Lebannon Valley would be a better place. At the next
drivers meeting, maybe we could have some official signal to get the
flagger's attention for a blue flag. Waving arms, flashing headlights,
etc... Pics from Ray Covino:
Drag Racing: http://picasaweb.google.com/raymond.covino/CARTCTLRP/photo#5078645871430871858
and http://picasaweb.google.com/raymond.covino/CARTCTLRP/photo#5078645931560414018

Tire Temps (outer-middle-inner), in the pits after session 3:
LF 196-183-178
RF 163-171-186
RR 131-133-144
LR 156-161-155

Filled up the tank at the track pumps ($4.80/gal for 93 octane, btw),
and checked with the grid guy to see how long open track would go,
until time trials started. He said 3, so we took a break for lunch at
1:45, and I rolled back out to grid by 2:20, only to be told that
they're setting up for time trials. Please, please, please have
consistent communication with everyone. Maybe a dry erase white board
with a master schedule, so last minute schedule changes can be shared
with everyone. The Camaro is happy with 20 minute sessions, but more
than that, and the oil temps get too high and the V710 tires overheat
(I got the left front at 195 in the pits after one of the faster
sessions). The T56 transmission is starting to go as well - funny
clicking noises on decel in 1st gear, and I get a little grind every
time I downshift into 3rd for the back straight. I've got a spare
waiting, and I'll rebuild this one with good parts eventually.

A peave - Limerock Park closed the track several times the day to run
construction equipment across. Would they have done this for the
Porsche clubs... We paid for the track, and they took time away. Maybe
red-flagging the session would have minimized the disruption?

Time trials started quickly enough (only 15 minutes to set up the
timers and convert over), and people gridded by car number in groups
of 3, split every 20 seconds or so. We'd get a 1 lap warmup, 2 hot
laps, and a cooldown. A light rain started half way through, and they
decided to hold off for 15 minutes until it cleared & dried up. I saw
#40 in the hot pits, so I decided to grid. It was finally our turn to
move into the hot pits, since we'd be the next run group, and of
course, the rain came back. Track went cold again, and 20 minutes
later, rain stopped (I thought it'd be a great learning experience to
run in the light rain to help my driving skills and keep the racing
line a bit drier, but CART club officials thought otherwise). We were
allowed 2 warm up laps to help dry the track. I was out first, then a
fast CRX also in the 1.03's, and a very clean black Fiero. The
concrete was very slick on cold tires, and the asphalt a little less
so. A few times the car attempted to swap ends when I fed the throttle
in a bit early, but not bad. Once the Kumho's got up to temp for the
2nd warm up lap, I could actually start driving it pretty hard. Thank
goodness for soft new tires! On the 2nd lap, the corner stations were
waving a yellow, which I thought might have been for me to take it
easier on the warm-up laps. Once I made it to the uphill corner, I saw
why - dirt ALL over the track. It turns out the Fiero had gone off
track, but saved it. We all got black flagged while the track workers
swept it up, and back out for our time trials. Everything went
smoothly, didn't make too many mistakes, but I was still cautious as
the track wasn't nearly as sticky as before the rain. Managed to get a
1.03.680, which put me in 2nd place for the E-mod class (data shows
130 before braking for big bend). First place was for a 350Z driver
who got a 1.03.3xx (Kyle and the other Evo had left after the rain
started). Another stand-out was the AMG Mercedes that was in F-stock
and ran a 1.03.xx! That's moving!
http://picasaweb.google.com/raymond.covino/CARTCTLRP/photo#5078646842093481074

TT's finished around 4:30, so we still had some open track time. I
wasted 15 minutes with the data acquisition system & Windows Vista on
the laptop, gave up, and headed back out on track for a few more laps.
I was released out of the hot pits and saw the gorgeous red ZR1 ahead,
who was also running in the low minutes range, and would be great to
follow and maybe learn a better line. At west bend, there was a HUGE
cloud of dust, and I saw the ZR1 slowly rolling off the track before
pit entrance, with a cloud of smoke behind it. Kept going for the next
lap when the session was black flagged, and saw his front left wheel
was cocked funny. It turns out his CCW Classic wheel (old style, same
as what I've got) had cracked off the center section at the base of
his spokes. He did a great job saving his car at a fast corner, with
only minor damage to body work. CCW has a revised center section with
2mm thicker spokes that fixes this. Hopefully they exchange the center
pieces for no-cost on these expensive wheels. CCW has a great rep for
customer service. Time to make a phone call, and get that taken care
of...
http://picasaweb.google.com/raymond.covino/CARTCTLRP/photo#5078644604415519186

Overall, it was a great day and another fun event put on by CART-CT.
Too bad there aren't any more Limerock dates with this club. I had a
great time.

Oh yeah - the crazy valve cover TIG welded breather towers we fabbed last week with baffles and
modified AMW catch can on Mark's car finally fixed his oil blowby
issues! He came in after the first session (still on street tires and
brakes - I could smell his car halfway around the lap!), and was
skipping around like a little school girl doing the happy dance! :)

Nice 1st gen: http://picasaweb.google.com/raymond.covino/CARTCTLRP/photo#5078645983100021586

Mufflers?!!

I must be getting old (over the hill, aka 30 years old, as a friend of mine says!), since I think the Camaro is a bit too loud (that, and LimeRock has a very strict good neighbor policy at 83 dBa). I picked the Dynomax UltraFlow welded muffler - part #17517. It's a 3.5" center in/out with a 4.5"x9" oval canister, 14" long. The sound is rated "Sport", so it shouldn't be as obnoxious as the bullet mufflers that have a "Race" rating. It flows 2200+ cfm (probably maxed out Dynomax's flow meter gauge, they use 20.3" of water for the pressure), and is recommended for 1000 loss-free horsepower. It's on page 187 of their catalog at http://www.dynomax.com/ecat/pdf/TENNECO_DYNOMAX.pdf.

3rd Link Excel Spreadsheet

3rd Link Excel97 Spreadsheet

Watkins Glen DL90 data from the COM SCC time trials on 4/24/07

C5 rotors after Watkins Glen
Wagner BD125539, Made in Canada

Brake pad wear

Before 2 days at Watkins Glen:

Rear:
PFC 90's 0413.90.13.04
.496, .471, .448, .405
Drivers Rotor .780"
Pass Rotor .485

Front:
Wilwood Polymatrix B - 15B-5939K (7420 w/ bridge bolt)
.800" thick - all (new)
C5 Rotors (new) 1.263" (drivers) and 1.265" (pass)

Wear: I'll update after watkins glen

]]> Both front rotors cracked heavily in half at Watkins Glen.
Front Pad wear :
Pass inner: .690 at front and .602 at rear, .635 middle top and bottom
Pass outer: .638 front and .620 rear, .609 middle top and .640 middle bottom
Drivers inner: .638 front and .622 rear, .626 top middle and .642 bottom middle
Drivers outer:.722 front and .625 rear, .673 middle top and bottom

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

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.

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

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!