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PostPosted: Fri Nov 20, 2020 10:59 am 
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Turbo Slant 6
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Joined: Fri Dec 30, 2005 2:49 pm
Posts: 991
Location: Houston, TX
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Last fall we built the Turbo Dart, tried to race it, and had problems. After that race our engine had very bad compression, and we found a chunk of piston skirt in the oil pan, so the first order of business was to finish the race block that we'd been slowly assembling for over a year: a 1970 225 truck block and forged crank, with oiling mods performed on both per the Dutra book. Bored out to 3.445" (87.5 mm) to take the Silvolite 1291 pistons, 198 rods, and moly rings I purchased from DusterIdiot a while back. We swapped over our Dutra-blueprinted HV oil pump and the A-body pan modified with extra oil fittings from the old block. The long rods would've upped the compression too high for our shaved big-valve head, so I had another head cut for my older set of (engbldr) big valves, which needed to be cleaned up slightly. Final SCR of ~8.6:1, which is almost exactly what we had the last race with a shaved head on a stock short block. Used a fancy Aussie head gasket Lou gave us last year, clamped down with the same ARP studs we've been running for years. Also swapped over the same stock 1973 camshaft, but this time with a little more advance for better power down low (ICL at 104° if I recall right).

Then our first two races in 2020 got COVID'ed, so naturally we didn't work on it for a while and instead focused on other projects (house, car trailer). I eventually fixed the issue with the right rear brakes; turned out one of the shoe hold-down springs need to be shimmed on the backside so it wouldn't rub on the weird drums that came with this 8.75" rear. Bob took the time to weld up all the holes in the firewall and paint the engine bay nice and pretty, then we finally got the engine installed sometime in September. After another few weeks of wiring and fabrication, topped off with what has become the EVR trademark week of no sleep leading up to the race last weekend, we ended up with... well, this is what it looked like after the race:

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Short version: Microsquirt, used LS3/L76 coils and injectors from the Pontiac G8 I blew up in 2014, used late-90s GM truck throttle body (4.8/5.3 Gen-1 LS), Gill Welding fuel rail, and an ugly one-piece intake and exhaust manifold fabricated by me. More details to be found here, but long story short, we got the engine just about ready to fire on Thursday before the MSR Houston Lemons race. We ran into an issue with our fuel rail leaking after we initially tightened the return fitting way too tight and then removed it to replace it with a plug. We called Gill Welding, who helpfully overnighted us another rail to arrive by Friday afternoon.

We got to the track about 9:30 AM on Friday. Bob and I continued finishing details on the Dart like installing the new throttle cable, cleaning up some wiring, and other stuff I'm certainly forgetting. The new fuel rail got to my house around 11 AM, so Hayley went to grab it and pick up various other stuff we'd forgotten. Got the new rail installed with a new plug in the front, and it didn't leak! The car was peeing fuel back where the new pump and filter are mounted, but we just had to tighten some newly-installed AN fittings. Bryce Gill called me later that afternoon to make sure I'd received the package; I appreciate him following up.

With everything connected the engine fired up almost immediately, but it wouldn't stay running. Luckily a couple of our guest drivers were familiar with Mega/Microsquirt and random GM sensor issues. Turned out Bob had wired our LC1 wideband to the wrong Microsquirt O2 sensor input, so it was being interpreted as a narrow-band and reading dead rich. (At some point the header started glowing from the ECU trying to lean it out so far, but sadly I didn't get a picture.) That fixed, the engine stayed running but idled at about 2000 RPM. Our brand new IAC valve was unused because Microsquirt can't drive a stepper-motor IAC by itself, and unfortunately since it had never been powered it was hanging partially open and providing a big vacuum leak. We pulled it out and replaced it with a plug we fabricated from parts of the old IAC valve that came installed in the used throttle body, and that made it idle fine. A few tweaks to the fuel map, and we drove it down to the track shop.

Jim at the MSR-Houston garage got it dialed in great on the dyno, and he also gave us a sweetheart deal with the billable hours (the first visit is always cheap to get you hooked :lol: ). Unfortunately, even with the lightest spring installed in our new boost controller, we couldn't keep the boost limited to 5-8 psi where we wanted it. I think it hit 20 psi on full throttle dyno pulls. It was also still running pretty hot, but it was a brand new engine build, so we decided we'd see how it behaved on the track in the morning before we did anything new (also it was pushing 1 AM by the time we were done at the dyno). After another 6 hours of sleep, I installed a new cable stop on the throttle cable, which was a little long under the dash, and I wired the transmission kickdown lever about 3/4 of the way open because we didn't have time to install the Bouchillon cable kit I bought. (They include detailed installation instructions for all manner of carburetors but not a GM truck throttle body... who'd have thought?) Bob tidied up all the under-hood wiring with a lot of convoluted wiring loom. We also changed the "break-in" oil just to be safe, but it looked fine coming out. We sent our other car, the 1941 Oldsmobile 98, out onto the track a few laps after the green flag so that it would stay clear of the initial rush at race start. The Dart was finished and made it through tech inspection a couple hours later, and I took it out on track.

The good news: in short, this car is a !@#$%^ monster now. I'm sure there's still some turbo lag, but compared to its performance last year I sure didn't notice it. It seemed like the boost gauge was ready to go positive as soon as I put my foot down. MPFI is basically magic. The bad news: it was still running hot, and it could still get way overboosted if I gave it too much go-pedal. Over the course of Saturday we tried a couple more things to keep the engine cool, including building a mount off the bumper brackets to stick our huge intercooler a foot out in front of the radiator, since a lot of people were telling us it probably impeded airflow to the radiator. It didn't make a bit of difference. Coolant temp would still get up to 250 if you drove it in anger for a couple laps, even keeping the boost down to 5-6 psi with your right foot (which was an effort). Laying off the boost completely would let it cool back down to 230 or so. Although the car was running much better and with more power than our previous race with the blow-through carb, the overheating behavior was pretty much identical. About an hour before the checkered flag on Saturday, I brought the car back in from a test run and suggested we just remove the intercooler entirely, leaving the turbo piping disconnected, and run the car NA to see what coolant temps looked like (which we can do now because the car has MPFI and a decent fuel map for no boost). That done, I headed back out and put down a few laps in anger, after which the temp was still at 240 and would probably have kept going up. This confirmed our suspicion that while the turbo certainly made things worse, it wasn't the root of the problem.

As the previously-linked threads will detail, at our previous race in November 2019 we suspected an issue with our engine block's ability to cool. That block had always run pretty hot, even normally aspirated. It actually gave us some overheating issues at its last race before adding the turbo (March 2019 at NOLA), but after that race I found the spring in the upper radiator hose rusted and collapsed in on itself, so I assumed that was the main issue. Then at the first turbo race we discovered in testing that the pump stopped flowing water over a certain RPM level. With this in mind, we took several steps to reduce the chances of cavitation on our new turbo block this year. First, we bought a fancy Flowkooler water pump and an under-drive pulley. Then, after noticing the difference in pump cavity depth between early and late 225 blocks, we built and installed a shim plate to the back wall of the pump cavity to fill most of the dead space behind the impeller. We also acid-flushed the block, which had been steam-cleaned at the machine shop already. In short, we were pretty doubtful our overheating issues at this race were still a result of the block's ability to flow water.

That only left one suspect: the radiator we hadn't changed since... late 2015? This is where we suddenly felt very stupid and wished we had been taking better post-race notes for the last few years. Remember how I said our previous block always ran hot? Well, our original 1964 engine before that had been retired due to a large crack in the cooling jacket. We'd limped that engine along for a couple years by periodically adding Barr's Leak radiator sealant. :oops: It did overheat a couple of times when enough of the sealant washed out for the coolant level to drop, but other than that, the original engine had historically run very cool (before and after a rebuild) with this aftermarket radiator. So we probably didn't take notice if the average coolant temps had started to climb for its last couple races due to the radiator clogging. And then when the new engine ran hotter on average, we blamed the engine block rather than considering how much Barr's Leak we'd poured into the radiator. Then we added a turbo. Yes, we are very stupid sometimes.

Luckily we still had our old radiator, the same big cheap aluminum universal Chevy radiator from Summit. It had been removed back in 2015 after the car slipped off the jack and dented the bottom few rows. It didn't leak, but we decided to replace it out of caution. So one of our teammates drove back to my garage to pick it up while Bob and I performed some baseline temperature testing at idle with the suspected clogged radiator. And clogged it was. Just looking down the return-side radiator end tank with a flashlight, you could see the water coming out of different tubes at very different flow rates. We repeated the same testing after installing the old dented radiator, and quickly realized it was cooling significantly better. The visual flow out of the tubes into the end tank was also much more uniform.

So... Sunday morning, I took the car back out and it ran much better. I still got it up to 230 under boost, but it seemed to level off there as long as I kept the boost down in the 5-7 psi range. So we probably have a little more work to do (like properly ducting air through the radiator, getting a more efficient radiator in general, and/or reducing the size of our massive intercooler), but it's now properly raceable. We also need an external wastegate, or a smaller turbo. I put down a 2:12 lap at MSR while keeping an eye glued to the boost gauge and never giving it much more than 50% throttle, which is in line with my average race times from a few years ago with a healthy NA engine. That same NA engine gave me a 2:07 under white-knuckled full tilt boogie conditions, so I'm optimistic that the turbo will get my best time down to two minutes once I can drive the car and not the gauges. We will probably need more rubber under this car at some point.

All in all, this was the proper "development" race we wished we had last year. We knew we wouldn't be competitive until the bugs are all worked out, but we think we've done a good job getting it running well, and we have a plan for future improvements before our next race. Next step is to get it road-legal again so we can do testing more easily.

In other news, The '41 Olds came back to the paddock late on Saturday with one of its eight rods knocking to be let out. Since we still wanted to be able to drive it onto the trailer, we retired it for the rest of the race. The transmission was also on its last legs, and we have no desire to rebuild the original drivetrain, so now we're putting serious thought into what to swap in. While Bob and I had originally argued over what weird original engine to use (he wanted a Duramax diesel, I wanted a Jag V12), we now realize that we need to keep it simple. The Olds has always been a "low-effort" car, and with the Dart now loaded with complicated technology, we really need to have one car that just stays running with minimal thought. A carbureted slant six and 904 makes the most sense since we know how to make them work and we have numerous spares of both. Unfortunately that's just what everyone in Lemons expects us to do, so we're a little torn about it. More thoughts to come on that, but probably not until 2022. We've had our share of new-build fever for a while.

Some members of our team also brought home a trophy from the awards ceremony on Sunday. Knowing that our team has historically run the potluck dinner at this race (which obviously wasn't happening this year), Lemons contracted us to provide food for all the Lemons staff for the weekend, since they can't do their normal restaurant shenanigans under COVID conditions. Well, Carrie and Hayley took charge and knocked it out of the park. The Lemons staff was so impressed with the food service that they gave us the "Life of the Paddock" award. While normally awarded to teams that provide the best paddock-party hilarity, in the pandemic era it is now mostly reserved for teams that keep the spirit of the Lemons paddock alive in a COVID-safe manner. It was good to see Hayley and Carrie get specific recognition, as most of our team's notoriety has previously centered around the dumb $#!+ Bob and I do.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
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PostPosted: Fri Nov 20, 2020 11:57 am 
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Supercharged
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Nice! Thanks for sharing.


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PostPosted: Fri Nov 20, 2020 12:02 pm 
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Very cool report Frank! Thanks for sharing!

Any plans for RA or Barber..?

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PostPosted: Fri Nov 20, 2020 2:22 pm 
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Turbo Slant 6
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Joined: Fri Dec 30, 2005 2:49 pm
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Location: Houston, TX
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No, we need to take some time to make a couple more modifications and get the system really dialed in before we go to another race. Assuming that the "Gulf Region TBA" Lemons race in March actually happens, that will probably be our next Lemons appearance. The Gulf Region spring race has been NOLA for the last couple years, but I don't know why it wouldn't be confirmed yet unless there's been a change...

One other thing I forgot to mention that we changed Sunday morning: We drilled out the holes for the internal wastegate to try to let more flow through. The main hole under the flapper valve measured about 13/16", so we drilled it out to 7/8" (because that's the largest stepper bit we could find). Pohlman had previously drilled a smaller hole in the partition between the divided halves of the housing (which I'm surprised wasn't there from the factory). We also bumped that hole up a couple sizes. Unfortunately it didn't make enough difference in the controlled boost level for me to notice on track. The flapper valve itself is about 1-1/8" diameter, so there's not much farther we can go. Hence the decision to go to an external wastegate (or smaller turbo if one falls into our laps).

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
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PostPosted: Fri Nov 20, 2020 9:56 pm 
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Supercharged
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Joined: Thu Jan 27, 2005 8:32 pm
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Location: SW Washington
Car Model: 1965 Plymouth Barracuda, 1954 Dodge C1-B8
Great report! I'm glad things are working better.

Boost control valves only add boost on top of whatever the wastegate spring (and pressure on the swing valve) gives you. You need a wastegate actuator from something that runs the amount of boost you want or less. Diesel stuff is far too high-pressure. Or, even easier, you could add a hefty spring (think clutch not throttle) to help open the flapper. That will bring the boost down.

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PostPosted: Sat Nov 21, 2020 3:21 am 
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Wow, quite the journey, and writeup. Thanks for sharing, Frank. Can't wait to see you guys at a Lemons race and maybe drive that sucker. Seems wastegate is the biggest order of business.

Kudos!
Lou

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