Here’s “boost creep”: an uncontrolled increase in manifold pressure, seen here as the light blue “MAP” trace at the center of the figure. This is with a 4-lb spring which in a perfect world limits boost to 4 psi, but the manufacturer notes that actual boost will vary engine to engine. In mine it’s about 7 psi (150kpa), which is fine if it stays there. It holds pretty well until about 5000 rpm, but then the exhaust gas volume becomes too much for it to vent off and the turbine speeds up and increases boost. I let off the gas when it hit 13 psi at 6100 rpm because it was trending upward pretty fast (and because I was already going 84 mph). The right way is to do all this on a dyno – maybe after boost is under control.
Parts were (again) ordered to change to a dual 38mm wastegate setup. I figure that worst case, the two don’t do the job and the header has to be redesigned, and both will still be needed in that case so they aren’t a waste. Somewhat related, I found this funny quote which is a pretty good description of what it’s like to live with a turbo engine, where:
… it’s like having a cokehead pornstar girlfriend. There’s going to be unparalleled excitement and thrills, but a lot of unexplainable downtime and a likely violent ending that leaves you broke and insane…
Back-filled 2011 ; all early posts are under the “Archive” link above.
Disconnected the upper wastegate hose to ensure there’s nothing keeping it from working properly but boost creep persists. I had a talk with a buddy who really knows turbo:
“You increased compression 8:1 to 9:1 (~12% more flow), right?” Yes
“You added cams that flow more air.” Yes
“You switched from a 0.82 AR turbine housing to a 1.06.” Yes
“You’re running E85, which produces a lot more exhaust gas than gasoline.” Yes
“You built an exhaust header with poor flow to the wastegate.” Um, yes
He went on to explain that the 1.06 AR turbine housing is far less restrictive to exhaust flow. That’s a very good thing but means that given the choice, exhaust gas would much rather go through a low-restriction turbine housing instead of making a hard turn into a smallish wastegate. He recommended one or more of the following:
Change the geometry of the header to provide a more direct shot at the wastegate: This is the right way but there’s no room
Add a second 38mm wastegate: There’s room, just
Replace the single 38mm wastegate with a 60mm unit: The “nuclear option.” Builders use these to regulate 1200-hp engines, but much more often, as a Band-Aid to limit boost creep caused by poor wastegate routing. Not an option because chassis tubing blocks the area.
Of the above, adding a second 38mm unit works the best short of starting over. For what it’s worth, two 38mm wastegates have the equivalent valve surface area of a 54mm unit, so it’s not vastly different than going with the 60mm unit.
Well that didn’t last long. Woke up this morning realizing I didn’t need some of the parts ordered last night for the exhaust modification, while a couple other parts had been forgotten. Canceled those parts, then found the wastegates are backordered with an unknown delivery date (at least from this vendor) so everything was canceled. It’s not entirely bad as it gives time to do a few more tests, like disconnecting the upper hose from the wastegate (which can keep the wastegate valve shut if pressurized, increasing boost). It “should be” zero but if it isn’t that would do it, but if it’s zero, that leaves wastegate routing and/or the engine changes (compression, cams, and larger turbine) as causing the wastegate to be unable to regulate a setpoint.
It’s too warm and humid to be doing much in the garage so the time was spent back-filling the 2012 blog.
I’ve always wondered why I had such a hard time clocking the turbocharger sections. The center section is free to rotate with respect to both the compressor and turbine housing but not just any way I want because – at least with Garrett units – the 1.06 A/R turbine housing interferes with the oil and coolant hoses. Worse, once it’s clocked it can be difficult or even impossible to tighten the turbine housing bolts, and that was when I noticed the big-ass snap-ring on the compressor section. With the suitable snap-ring pliers, the compressor side can be removed entirely which makes it much easier to tighten the turbine housing bolts and the coolant and oil fittings.
A lot has been happening and it’s become apparent just how much I changed and how much has to be redone. Moving the turbo had all kinds of unintended (read: not thought through) consequences; every hose and tube connected to it changed. A fair amount of today was spent fabricating the seemingly simple intake elbow, but which had to be made just so in order to fit. Because I switched to a different type intake air temperature sensor, it needed a custom mount (thankfully I already measured its resistance curve). The new air sensor has a much faster response time, important in a boosted setup and is a Bosch 0 280 130 085 if you’re interested.
As you can see from the pictures the intake tract is very compact and the only real concern is how much the engine moves around due to torque. Don’t want engine movement to be able to pull a hose off, which means the fore and aft engine mounts need to be fairly stiff. I have a block of Delrin to fabricate a stiffer rear mount if necessary.
Moral of the story is that I need to quit fussing with the car and just drive it. Unfortunately there’s still the big project of fabricate the ductwork to get air to the intercooler. It’s either going to make the car even look more comical – or more bad-ass, not sure which.
While there’s still stuff to do before first start the list is getting shorter. There’s fabricating the wastegate tubing down to the exhaust, lengthening the wires for both the boost controller and the O2 sensor, finishing up the coolant bleed lines, and not much else, so it’s safe to say after checking everything for tightness, it should be running pretty soon.
Oh, almost forgot, that last picture of the wiring, notice how the green wire has backed out of the relay connector. I wonder how long it’s been that way. You find a lot of stuff isn’t as it should be when you take apart a car.
Lastly, if you want to comment on anything posted after today, click on the post’s title, which will almost always be the date, then scroll down to the bottom for the comment field.
Made good progress on the new website; one of the sticking point was providing easy visibility into the old diaries and it’s more or less squared away. There’ll be four search methods: post by post, by year and month, a Midlana-centric Google search bar, and categories and tags. It all works but I need to format the categories and tags better, then start back-filling the old diaries. When I’m in the middle of something that’s going well I tend to keep going even at the expense of other projects, but car progress was still made. By the way, one thing very noticeable is how much clearer and sharper the images are. Even though they’re the same root images, the web software apparently handles them different and they look way better.
Sunday was spent deciding where the dry sump tank, Spintric air/oil-separator, the relocated ethanol sensor, and the new fuel filter will go. Both the Spintric and ethanol sensor are now mounted in their final positions. The dry sump tank’s position is set; it just needs the mounts, and the fuel filter’s position is loosely decided.
On the engine front, Drag Cartel is making fast progress now that they have all the machined and cleaned parts in-house. It may be here as early as the first week in June so I need to keep working on the ancillary projects. The intercooler mount will probably wait until the new engine’s in place, unless I get everything else done first.
The forum is back online and the forum software updated; this should be the end of interruptions for a long time.
Intercooler placement was finalized (read: “make a decision and move on”), placing it on the centerline of the car. In a straight-on rear-end accident, if it gets pushed forward it’ll hit the main roll hoop diaganal, and if it somehow gets past that, it should pass between the seats. With that out of the way, the end tanks were finished and welded on; in 15 years, this is only the third time the cooling fan has come on – welding thicker aluminum requires significant current. As to how much air can be fed through it, I’ll be learning along with you guys. An F1-style scoop would certainly work but will block rear visibility. Another approach is having scoops protruding from each side feeding air in that way. All will become clear after some aero testing.
It’s official, the cylinder head and various engine parts were delivered to the engine builder, Jeremy of Drag Cartel; we met midway at an import car show. I only took a few pictures because it irks me that so many people do the “I’m different – just like all my friends” thing, a lot of chrome, a lot of turbos, and not much independent thinking, including a surprising lack of air filter elements. Independent thought was noted, such as an old Honda 600 with a Honda bike engine (and gas tank) that fit like a glove. Jeremy’s drag car was a work of art, very elegant; it was clear that someone knew what they were doing. That engine generates around 400 hp at 10,000 rpm. I noticed that the car used the same remote oil filter adaptor I am – the one where the nut backed off, leaving me stranded with oil everywhere. I let him know. I got there really early to hand off the parts to Jeremy before the crowds arrived, and arrive it did. I left about 10am and there were 100s of Hondas backed up out to the freeway heading toward the event. The police took notice as well, with several cars pulled over at any one time. Get a bunch of young roosters together and there’s always one that has to show off, and presto, red lights. Need to learn to contain it, guys.
Lastly, work on the new website continues. Right now I’m trying to figure out how to use the blog page for this year’s blog, but somehow have an archive directory to previous years.
The re-designed intercooler placement takes shape. New end tanks have to be made, both because there’s not enough space for the previous ones, and as my buddy Alan reminded me, with around 20 psi boost pressure, that ends up being hundreds of pounds of force. Given a chance, that force would flex any flat-sided tank, work-harden the welds and cause them to crack; the new tanks will be cylindrical to avoid that. After taking these pictures, I changed the tube routing on the inlet side. As shown, the flow would have had to take a very tight 90-degree turn right out of the compressor, which is terrible for flow. The turbo outlet will be rotated to point downward and the flow will instead be fed through two large-radius 90-degree bends feeding into the center of the end tank from below. It’s also cheaper because the U-bends are already on-hand.
What will be decided later is where to get the cooling air from. Which approach to take will be determined with some test drives, string on sticks to determine flow direction, and clear U-shaped water-filled tubes serving as manometers to determine relative pressure. Regardless where it comes from it sure is going to change the appearance of the car – so be it.
The new engine is slowly coming together; shown is a coated piston. This week, the pistons, pins, and rods will be sent to ERL where the block will be honed and the short assembly clearanced and balanced. After that it’s back to the engine builder to add the inspected cylinder head and then we’ll be back in business. Reminds me that I need to send the head and various parts to the engine builder pretty soon so that I’m not holding up anything.
In other news, as seen from above, the driver’s right-hand shoulder belt bracket was found misaligned but wasn’t loose – I didn’t set it that way. Seems the spin at Willow may have been more forceful than I thought and with the car spinning to the right and catching the dirt bank, I apparently tried to keep going toward the left. It’s crossed my mind a few times that the HANS may well have prevented some serious neck injury.