Qwkswede's Red 740 Wagon. Part Deux aka Superfridge

not too shabby

Altitude? What altitude? Freakin awesome.

Wow, that brick is quick, congratulations Ken!

I was curious how Bandimere went from ~5500' elevation to a ~7250' density altitude, but found the explanation here (nice site for racers):
https://airdensityonline.com/2016/08/measuring-racetrack-atmosphere/

Out of curiosity, what's the standard way of talking about "boost"? Is it additional pressure above ambient (~84kPa around Denver), or pressure above sea level (100kPa)?

bobxyz said:

Wow, that brick is quick, congratulations Ken!

I was curious how Bandimere went from ~5500' elevation to a ~7250' density altitude, but found the explanation here (nice site for racers):
https://airdensityonline.com/2016/08/measuring-racetrack-atmosphere/

Out of curiosity, what's the standard way of talking about "boost"? Is it additional pressure above ambient (~84kPa around Denver), or pressure above sea level (100kPa)?

Click to expand...

Depends. In a car?s gauge it?s differential; Megasquirt sees it as absolute. In an airplane, it?s absolute.

bobxyz said:

Wow, that brick is quick, congratulations Ken!

I was curious how Bandimere went from ~5500' elevation to a ~7250' density altitude, but found the explanation here (nice site for racers):
https://airdensityonline.com/2016/08/measuring-racetrack-atmosphere/

Out of curiosity, what's the standard way of talking about "boost"? Is it additional pressure above ambient (~84kPa around Denver), or pressure above sea level (100kPa)?

Click to expand...

I think it's a bit ambiguous really. People use whichever version sounds better. Mechanical boost gauges read zero when the engine if off, even at altitude. At least the ones I have used, vdo and autometer. So my mechanical gauges don't read the same as the absolute pressure I see inside megasquirt data logs.

I set the target at 220KPA absolute on the closed loop boost control in megasquirt. And that showed about 20psi on my mechanical gauge in the dash. I really work in absolute pressure mostly because I'm always looking at the megasqurit logs. But people like PSI. Soooo.

And the altitude at Bandimere is a bitch. I think the track there is at almost 5900' ASL. It's noticeable when you drive there. And add any hot weather to that on top of a huge acreage of blacktop and air density starts plumetting. Last night the air was really cool and dense. I didn't even look. But everyone was running really fast for change.

I got sucked in to the challenge of laying down an 11 second pass after the bit success the last couple trips to the track. So I packed up my helmet and went out to Bandimere Speedway for the official last Wednesday night on October 13. It was cooooold. 40s I think. I eeked the boost control up to 21 psi and this motor combination just loves it! I'm certainly not near the limit of the turbo and airflow, because every time I add 1 psi boost it seems to pick up 20-30 hp. My poor trans is hanging in there like a champion. It has the basic accumulator mods and it works great without a hiccup.

First run the car went 116mph!! BUT they seem to have given up prepping the track. Probably parked the tractor and glue sprayer for the winter.... So traction was horrific. It was also very cold. So I was back to 2.6 seccond 60 foots. This time spinning all the way through first and into second even if the boost came up hard. I just couldn't feather the throttle enough to get traction.

I ran some mid 12s. I met a couple closet Volvo lovers that came to congratulate me and see what I was hiding under the hood. People always expect a wild swap. It's cool kid stuff to have a 16 valve motor these days, since the heads are super rare now. So many people have never seen a 16V volvo motor in person. I remember them in the junkyard every single time I visited.

Good times, and just a little disappointment. I think I'll pick up some drag slicks or drag radials so I can street drive on them a bit. And next year I should be able to lay down better 60' times. I'm also considering pulling the motor and putting some H beam rods in the bottom end. I am estimating about 400 crank HP right now. The tune is safe, good octane and all. But man, that does make me a bit nervous... I don't want to be the guy that lays oil down on the track and kills the fun for an hour. And ruins a good vintage 16V head too....

After the Fall fun at the dragstrip I was feeling pretty good about the car. And it was time to make an annual trip to California to visit my parents. So I put the winter tires on the wagon just in case it snowed. I loaded up my bike and went for a week long road trip. I put about 3000 miles on the car, and it ran mostly good the entire way. With a few issues mostly due to my custom work.

1. A Walbro 470 fuel pump is likely too much for a street driving Volvo. The amp draw is just ridiculous, and my charging system doesn't really keep up if I have to run the lights, heater, radio, etc. Normal road trip stuff.

2. My install of 8 gauge wire needed for the pump above caused some bad fuel smells that got progressively worse on the drive. It turned out I had gasoline getting pumped through the inside of the wires and directly into the rear hatch area. I pulled the pump out in California and made a temporary fix, but I think I'm going to install a more mild Walbro 340 soon. They draw 1/2 the amps according to the documentation.

3. I blew a turbo gasket on the way home. I think the long miles just loosened up some bolts and the stainless turbo gasket split. A bit of noise, and some loss of performance. But not a huge deal to fix.

10.!! Road tripping and old Volvo wagon is great! I pulled down 23mpg, and just cruised along at about 70mph. The amount of junk you can haul is just amazing. And I even had room to sleep in the back if needed. I took a nap or two on some of the long days across the west.

Good to know it was mostly uneventful, in terms of mechanical issues.

Interesting about the Walbro. I have a 450 in mine and it does fine with 12 AWG; so far no significant problems with fuel or wiring overheating. Hoping you figure that one out sooner rather than later.

Same here, have been running a gs450 for a few years without issues on a 2.5mm2 wire (13awg). I did kill an alternator last year (probably the worn brushes, totally disintegrated the stator), but didn't encounter any charging issues before with the 100a alternator and the 940 fan.

Is your fuel filter keeping up? Sounds like the pump is fighting something

I am pretty sure most cars that run these new big Walbro pumps from the factory are using a PWM strategy to control the pumps. So they don't really run full speed, full power all the time. I thought about replicating that with MS3 controlling the pump output. But that's a bit complicated for my simple case. I'm still tuning like it was 1995.

My car does charge good enough to start without trouble. So it's not a huge problem that has caused me problems. But I can see the volt gauge on my dash show about 12.6 volts max when cruising at night. It's just very marginal. And when you go into boost and clamp the regulator down on the fuel flow the voltage will dip into the low to mid 11v range. It took me a while to put together the voltage dip under load. But I think it has to be the larger fuel pump. Injectors don't draw that much extra power under boost. And the ignition system shoudn't change it's current draw substantially either. So it has to be the fuel pump under load...

Fuel filter is fresh, I run the Volvo factory style canister. I assumed that thing flows enough to not be a restriction. I made 600hp without wavering pressure with one of those in the past.

Interesting, not ideal from what it sounds like. I'll have to stick a voltmeter on my car to confirm, maybe it was part of why my alternator died. I do like the ability to keep it e85 compatible if I get wild ideas in the future, that's why I chose it over the 255 in the first place

It's March now and drag racing season is just around the corner so I need to get started on some maintenance and improvements.

After the 3000 miles road trip in the fall I had to do some maintenance. I replaced a burned up gasket between the exhaust manifold and turbo flange. I did an oil change. AND I also rounded up a good usable AC condenser. I hope to get the AC system assembled and working before spring and summer start melting people. Beyond that, I am shopping for some wheels and tires to improve drag strip traction. I think a 24.5x8.5 drag slick will work. I'll probably order up some 15x8 steel wheels from Diamond Racing again. I can't seem to find anything better than that. Every oem Volvo wheel I have is like 5-6 inches wide which I don't really like with an 8.5-10" wide drag tire. I thought about a drag radial for some streetability. But there isn't really much in small sizes. So the mickey thompson or M&H slick will probably get ordered.

I want to keep the horsepower at it's current level for now. I have really restrained myself from buying a larger set of injectors. With the 80lb guys I am running now, I am maxxed out and that is probably a good thing. The car runs fantastic as a daily driver and is really fast at the drag strip. Any more and I'm sure I'll be breaking AW71s like candy canes. It's at a good place right now and serves as a street car in a way that my last Volvo wagon did not.


So for 2022 it will be good sticky tires and fine tuning the rest of the combination. I hope for some more low 12 second passes and lots of good fun daily driving. I'm sure there will be more modifications than that, it always gets a little carried away. I'll keep the thread updated as interesting things happen.

My summer of car projects completely disappeared because I moved to a new house in the mountains. I now live at 8200' above sea level. This has really caused problems for my engine's boost response. A Garrett GT3071 is apparently on the "large" side when you drive primarily above 8000'. At sea level this thing makes instant boost and lays rubber for miles in first gear with just a push of the gas. My new hood I'm lucky if I can make enough power in first gear to merge into traffic. 3-4 seconds on the throttle and into second gear the turbo starts cooking and I'll see the wastegate pressure 14-15psi. But man it takes forever to build boost. I might have to consider sizing down the turbo a bit just to make it more drivable on the street. The 16V motor lack torque, and put a slow spooling turbo on there, and it means the motor is struggling driving up my driveway at idle speed. I didn't build the car for once a year drag racing trips. Well... I kinda did. But it does haul lumber and junk from Home Depot pretty often too.

Not much mechanic work happening with this sled. Just racking up a ton of miles. I have some ideas for winter though.

Anyone have a suggestion for a smaller, but still 400hp capable turbo that can work at 8000-10000' above sea level? My barometric pressure reading when I turn on the key is 74kpa. I'd like to bolt it to my stock 90+ manifold. So a T3 flange would be ideal.

A Borg Warner EFR maybe? I don't know how to size those or what they spool like at altitude.
A GT28 something with a T3 housing??? Do those exist? Seems like they have T25 bolt pattern usually.
Or maybe I go for a Mitsubishi hybrid build. Like a TD04HL with a 20G compressor wheel.

Anyways. Just noodling on the possibilities.

EFR 6758 or 6258 seems like what you want. Turbine housings are limited to v-band or T4 though.

I'm on a GTX2867 Gen 2 with an ATP T3 .63 housing. Garrett doesn't make a T3 housing for the GT28 but ATP does, nicely done. I'm fighting a little of the same, going from sea level to 4000' I definitely lost that instant spool. Need to tweak some other stuff on the tune, easier whenever I get funds for the MS.

gsellstr said:

I'm on a GTX2867 Gen 2 with an ATP T3 .63 housing. Garrett doesn't make a T3 housing for the GT28 but ATP does, nicely done. I'm fighting a little of the same, going from sea level to 4000' I definitely lost that instant spool. Need to tweak some other stuff on the tune, easier whenever I get funds for the MS.

Click to expand...

I find the GT28 to be undersized with the ATP housing for a redblock, to the point where an old T3/T4 spooled better.

i think a s200 would probably work pretty good and they are cheap

https://agpturbo.com/borg-warner-efr-7163/

this with one of their t3 housings. The old 20v audi 5 cyl guys use them a lot and max them out on e85 at 30ish psi; they make 500awhp at that.