Kurt Bilinski's build

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ShadowCat38
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Re: Kurt Bilinski's build

Post by ShadowCat38 » 11 Oct 2016, 18:58

I'm following along on the blog, and all I can say is, "Wow!"

I've been waiting with baited breath to see how this turns out, and so far, I'm seriously impressed. Keep up the amazing work. I'm getting inspired just watching this come together.

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Re: Kurt Bilinski's build

Post by Midlana1 » 19 Oct 2016, 06:30

Thanks!

The last of the fiberglass was ordered. Paint prep can take a long time due to the endless hours of sanding. Paint color will be lime green because it'll keep the surface temperature cooler and doesn't show surface irregularities as easily as dark colors do.

While I can do composite when necessary, all this exercise has done is underscored my feelings that it's labor intensive, messy, smelly, hazardous, and fussy. The worst is the dust which lands everywhere, making it a health hazard pretty much forever. Couple that with having a garage attached to the house makes for a poorly advised setup. Even though I did as much as I could outside I still see a thin layer of it everywhere. If you plan on doing much composite work I highly recommended a separate workshop away from the house.

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Re: Kurt Bilinski's build

Post by Midlana1 » 16 Nov 2016, 11:51

I'm sick of sanding and every time I think about finishing the ductwork I'm happier doing something else. Still to do is drilling the mounting points for the intercooler section and drilling out the plugged up holes on the forward section - that's easy enough. After that, more sanding until it's "good enough" then the bits handed off for paint; I just don't feel like converting the garage into a paint booth, making more of a mess, then possibly getting pissed because the paint quality came out bad.

Yes I've been slacking off car-wise but not work-wise. As noted elsewhere I'm working on our yard (easier now that temperatures are dropping), redoing the koi pond system and adding a vegetable garden. The heart of koi keeping has always been the filtration system and much like the self-built car market, the koi industry is really small. This means (as with home-building cars) that the benefits of mass production never happens so equipment is expensive enough that it makes building it yourself viable. Suffice it to say, the pond filter is making full use of parts from Mcmaster, so if you like mechanical stuff, check it out in the Off-Topic section.

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Re: Kurt Bilinski's build

Post by Def » 02 Jan 2017, 15:14

Midlana1 wrote:I'm seeing all sorts of contradictory information about whether cam overlap is a positive or negative influence on a turbocharged engine. I could post quotes from sources claiming to know what they're talking about but it doesn't really matter since the engine's already done, but I am seeing two symptoms, both of which "might" be due to the cams: having to increase volumetric efficiency about 20%, and idle vacuum is worse than on the previous engine. Of course, the engine isn't fully broken in yet, and the larger turbine and higher-compression pistons may be contributors - I just don't know. I guess I just have to push forward with what I've got and see where it ends up. Worst case is the cams go back to stock, something not entirely terrible but it is something I rather not have to do.

In other news, testing has sorted out the air/fuel ratios. The new header is - not surprisingly - not great for boost control due to its so-so routing for the wastegate - I admit I wanted to see what I could get away with, and may have taken it one step too far. With the weakest spring in place, boost initially limits at ~150 kpa, which is good, but then it starts rising quickly, reaching ~180 kpa at about 6000 RPM. As bad as that is it might be okay if boost baseline is set to around 180 kpa - I think. Guess I'll find out. With our very warm and humid weather I'm hoping I don't have to make any changes involving welding.
Cam overlap is good for a turbo engine. There is really nothing different on a turbo engine vs. an NA engine. They both have a static pressure in the intake manifold and in the exhaust manifold, and both vary and change over the entire rev range.

A good flowing engine and turbo setup with good overlap for high RPM operation will typically have a positive intake/exhaust pressure ratio (intake boost higher than exhaust backpressure) until at least somewhere in the mid-upper RPM range. This means that during the overlap period you'll "clean out" the combustion chamber slightly. There's no way to "blow boost out" the exhaust ports unless you have like 90 degrees of duration at 2000 RPM. Doing the calculation for a typical RPM (>4000 RPM) and more typical 30-50 degrees of overlap, of which only about 10-30 deg of that will have any valve lift to actually flow anything meaningful, the intake charge would have to exceed the speed of sound for only some of it to go out the exhaust ports.

The above comes from 14 yrs of turbo engines and tuning them and putting bigger cams in them. I'm honestly a bit perplexed at the whole "blow the boost out the exhaust talk." I think that might come from way back in the day with really poorly flowing 2 valve pushrod engines that need crazy cam duration to get any sort of headflow above 4-5k RPM. So yea, if your duration at 0.050" is 260-280 degrees, it's going to run like crap outside of that narrow window of intake/exhaust pressure ratio and harmonics it's tuned around since the valves are both open for so long.


Onto VE...

Higher VE numbers on your Infinity VE table mean more flow, which means more power. So if you make a change and you need to add values to the VE table - you're making more power at the same ignition timing. It's that simple. :)



BTW, saw a recent log from maybe the Sept timeframe in your blog that had the engine going REALLY lean towards redline and the lambda FB fighting to keep it down and then the engine actually breaking up (possibly due to knock and fuel cut, possibly due to lean misfire). So I'd suggest you revisit your VE table even more. It's easy to tune fuel on the Infinity, as you just make some pulls and change things close to the "newVE" value and then check. I find it's best to add about 1-3% on the "far" side of the newVE value, as obviously that's a calculated value from a PID loop trying to hit a target. It tends to be shy of the target, so adding 1-3% gets you much closer to the actual value.

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Re: Kurt Bilinski's build

Post by Midlana1 » 03 Jan 2017, 07:12

Image

Thanks for the info, it's reassuring.

Regarding VE, I assume you're referring to this log above. The wild changes at the right are the consequences of hitting the rev-limiter and its associated fuel-cut. The "lean" reading is the direct consequence of fuel cut and is artificial. VE was set up to be within a couple of percent of optimum before switching to closed-loop and lambda is right where it's supposed to be. Is 0.75 lambda too lean?

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Re: Kurt Bilinski's build

Post by Def » 03 Jan 2017, 10:59

Ah - gotcha. A fuel cut rev limiter would make sense, I guess I wasn't expecting that due to the low RPM, but I'm guessing you moved it for testing.

I personally run 0.78 lambda on 93 octane E10 pump gas and 0.80 lambda on E85. My door slammer's engine isn't that far off yours. 2L SR20DET with a VE head (think Honda B/H series for a rough comparison), big 288/288 duration cams and 9.5-9.6:1 CR.

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Re: Kurt Bilinski's build

Post by steveo » 07 Feb 2017, 20:19

The air scoop for the intercooler is a thing of beauty Kurt!

I think you get one of those stick-on mohicans and stick it up there. Would look totally evil!

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Re: Kurt Bilinski's build

Post by Midlana1 » 08 Feb 2017, 06:31

Haha, that's a pretty good idea.

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Re: Kurt Bilinski's build

Post by freakynami » 18 Feb 2017, 05:06

I'm probably just being dumb, but I can't seem to find if/where you talk about which way "up" to mount the coilovers?

I see you've got the rears with the body downwards:
Image

Are the QA1s supposed to mount a certain way up? I had guessed that up the other way (body attached to the chassis, rod attached to the suspension arms) reduces the unsprung mass?

I see you built the fronts up the other way, but IIRC you swapped them around??

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Re: Kurt Bilinski's build

Post by Def » 18 Feb 2017, 05:54

The QA1s are monotube, so they can mount either way. A complete guess here, but I think they might be mounted body down to access the adjusters once installed. A few ounces of unsprung weight difference is worth it if that's how you can adjust your shocks!

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