that is a knock sensor but in my eyes makes not much sense because you not know the frequency where the knocking starts to get dangerous for the engine. every engine is different.
Yes, that's a knock sensor. There's one on each bank, between 1&2 and 11&12. I'm not even sure what those bolt holes are for, but they were unused and they're working well for knock sensors as they are at the top of the cylinder (but not on the head, as that has more "noise"). There is a formula you can use to get within ballpark: Knock frequency (kHz) = 1800 / (3.14 x Piston Dia (mm)) For 82mm, you'd get 7k; which is what I am using – in addition to "bracketing" the primary frequency to see if there are other more appropriate frequencies. Also, this isn't an on/off thing. You can see the noise of each cylinder increasing as RPM increases, and then set different thresholds of noise based on RPM. There is a distinct spike in an individual cylinder's noise when you get a ping. It's hard to miss. Here's a screenshot from one of the dyno runs where there was knock. The blue line (threshold) is increasing with RPM. Obviously, this isn't something I want to make a habit of, but I wanted to see where the limits were. Image Unavailable, Please Login
when you test on a dyno you can concentrate to the diagram for sure. but you not can go to the limit. but it depends on the kind of dyno if you only go a few seconds for max power reading or if you could go 10 or 20 minutes to test and adjust all. sure , a knock sensor is better than nothing, but the ECU has to be adjusted not at the limit, may be 15 - 20 % less. the fuel is not all the same at the fuel stations.
I think I have a final design for all three manifolds (4-6 and 7-9 are the same manifold, just rotated). All the critical areas seem to fit well. Vacuum ports were added, and I bumped the total height to 60mm to leave enough room for the ignition coils. The coolant inlets are essentially identical to stock (helps to have a 3D scanner), and the runners taper from 42mm round to the stock inlet shape. I am going to do one more round of plastic manifolds, and then have them made. Likely going with 3D printed aluminum. It has an almost sand cast look that I am hoping makes the manifolds look a little more pro and less after-market. Image Unavailable, Please Login Image Unavailable, Please Login
I remember years ago seeing a factory picture of an engine on a stand that had a metal bars reaching forward to those two tabs on the block to help support the weight.
They are cast in the block for the factory engine stand. We made this but its a copy of how the factory did it. Its designed so the parts that hold one case half come off so the case can be split. Image Unavailable, Please Login
Shame you can't use the plastic rapid -prototype parts. They look very nice. Just throwing this out there: Have you considered foundry companies to sand cast your rapid p-type parts? If you want them to look sand cast....
Thank you. I could print them in PET-CF or Nylon-CF; which can easily handle the ambient air temp of the engine bay (the custom dizzy cap is PET-CF), but the direct heat of the head and the coolant makes me nervous. I briefly looked into it, but I didn't find anything that was cost effective for one-off parts. Maybe I didn't look hard enough? I actually just placed an order to have these 3D printed in aluminum. It's technically an aluminum, silicon, magnesium alloy (ALSi10Mg); which should hopefully have a similar look to the block / heads due to the higher percentage of silicon (10%) vs the alloys used in CNC. Also, the 3D printed parts have a texture that looks similar to cast (at least more so than CNC)..Quick blurb on ALSi10Mg (example below). Image Unavailable, Please Login The prices for 3D printed metal have come down considerably recently; especially with the shops that farm out the machining overseas. I guess we'll see if the parts are actually usable when they arrive, but I am optimistic. Below is my receipt. With the accessibility of 3D scanners, CAD, 3D printers and cloud manufacturing, I feel like we're in a new era of hot rodding. Image Unavailable, Please Login
The technology today to custom make parts just keeps getting better and better! That sample part shown looks like the precision features are machined. Is this machining cost included in the price to rapid prototype the basic parts? The 3D parts do not need to be adjusted for Al casting shrinkage (solidus at ~1,100ºF). Beautiful work! Definitely in a new era of hot rodding.
Similar to cast, there's some post-machining work needed. I'm sure the flanges will need to be smoothed / leveled, and the ports should be cleaned up / polished, etc.. I'm no expert, but it's my understanding that ALSi10Mg SLM is not particularly known for shrinkage. The manufacturer guarantees the parts to be within 0.2mm of the designs. Fingers crossed. If this works out, I have a few other projects for the car that I'd want to use 3D printed metal.
In this case, the process causes shrinkage more than the material. I would expect these parts to meet their tolerance claim. It sounds like a 606X family of aluminum, most likely selected to work best with their process. In metal, I've only made Ti6Al4V parts. I was impressed with the properties and amazing geometries.
Status update. Chipping away at it. I received my new coolant hoses. I started prepping the throttle linkages as well. The hope is to maintain as much of the stock throttle linkages as I can. So far, it looks like it's mostly a matter of using longer connecting rods. The angles are a bit different, so some minor changes might need to be made to get the proper geometry. Intake Manifolds A bit to my amazement, it looks like they were made! I guess we'll see when they arrive (this week?), but the manufacturer sent me this single QC photo before shipping out. It's just one photo, but everything looks correct. Even the built-in vacuum port barbs. Still a little hard to believe. Image Unavailable, Please Login AC This might be a bit controversial, but I removed the compressor. It's bulky, heavy, and doesn't work particularly well. This should give the engine more breathing room (both physically and aesthetically). The plan is (in a later phase) to install an electric compressor in the front of the car (near the battery). This is another page from the Porsche (Singer and Theon) playbook. The electric compressors are more efficient and lighter. Plus, a marginal weight balance improvement. For now though, no AC (not like it worked particularly well in Miami anyway). Vacuum Block For some reason, I labored over this one for longer than I'd like to admit. The issue was trying to come up with a clean package that collected all vacuum ports, the MAP sensor, and the IACV. I think I found a temporary solution that I am happy with. If the metal 3D printing thing turns out to be viable, I may print a custom vacuum block. Anyway, the thought is that the entire vacuum block fixture would go where the old compressor was, and literally mounts to the same holes. It's tucked in the back, so it's hopefully less noticeable. The actual vacuum block (Holley EFI Vacuum Manifold) is installed inside the bracket, with the MAP sensor hanging off the back, and the IACV hanging off the side. Each bank's vacuum ports will meet in the middle (barbs poke through the rectangular cutout in the bracket. This allows the IACV to create a controlled vacuum leak that can control idle, cold running, etc.. Image Unavailable, Please Login Image Unavailable, Please Login
Very quick. I placed the order on May 25th (Saturday). I should receive the parts this week, which would be a total of less than two weeks for four 3D printed aluminum manifolds. Fingers crossed these are usable.
Thanks. That's similar to others I've seen (eg, the Jenvey "air distributor"). I've been trying to design something that combines the manifold vacuum, brake booster, IACV, and MAP sensor – all without creating a big mess and trying to be discreet. This is my current iteration. Each bank of vacuum ports collects prior, so you're only getting one vacuum port per bank. The extra 1/4" port is for the MAP. IACV and brake booster get larger 19mm ports (brake booster hooks up to the original hose that connected to the RH side plenum and merges with the vacuum pump). The plastic fixture shown is just a prototype in ASA (can't handle engine bay temps). Ultimately, I am leaning toward 3D printing (out of aluminum) a custom block that has the necessary ports and mounts to the old AC compressor bolts. That'll allow me to make it a smaller package. Although IMO, even this temporary fixture stands out less than the AC compressor did. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Status update. Intake Manifolds They're here! I did a quick test fit, and they fit exactly the same as the plastic prototypes. A few observations: They look more like sand cast than CNC – which is what I was going for. There are little textures and pitting similar to what you'd find with casting. It's not exactly the same, but I like it. The packaging was really good. They were individually wrapped in tissue paper and bubble wrap; which was then all wrapped again in bubble wrap. The matte is not a nice texture. It looks like gray primer paint. I've already placed the order for different parts and opted for the glass blasting – which is the other end of the spectrum. Interested to see how that compares. I post-processed one bank (strip the gray matte, polish the runners, etc.). I've been in the garage for the past few days hunched over the parts like a little troll with a dremel. Afterwards, they have a kind of gun metal look to them. The STL file I uploaded to Craftcloud was the same one I used for my plastic prototypes. The parts arrived with more visible geometry than I usually get with my printer – which I believe is due to the Craftcloud printers just being much better. I believe it's solvable by simply bumping up the quality settings when I do the export. The parts are absolutely usable, but the post-processing steps took longer. Moral of the story: upload as high of quality STL file as you can (seems obvious, but there are diminishing returns on that to the point that it can be counter-productive). I will absolutely be doing more of this. It's amazing. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Vacuum Block The prior post shows the latest iteration. I think I can do one more tweak to clean things up further, but it's pretty close. You can see each manifold has a built-in vacuum port; which will collect to a single vacuum line per bank. Now that I know I can 3D print metal, I will eventually design a one-piece vacuum block designed to mount to the AC compressor bolt holes. That should be even more discreet and feel more OEM. Image Unavailable, Please Login Misc. Just some odds / ends. I wrapped the BAT+ yellowed silicone in flex sleeve. I'm also experimenting with using P-clips (aka Adel / cushion clamps) on the trumpet bracket to keep things tidy. Side note, I really like the openness of the engine bay now. It means there's nowhere to hide stuff (eg, CIS bits under a big plenum), but it should look really nice once the engine is fully redressed. Image Unavailable, Please Login The three big ticket items were the manifolds, vacuum block / IACV, and throttle bodies. With those out of the way, I can start knocking out the smaller items like wiring tweaks. My hope is to have the car running again by July 1.
Thanks. I'm happy with how it's coming along. To me, it definitely has that BBLM inspired aesthetic. I might play around with taller trumpets after I have the car running to find that sweet spot in looks/sound/HP/torque.
Don’t be shocked if you’re trumpets are perhaps a touch too long as they are now. The capacity per cylinder, peak torque, power rpm range and intake tract length to butterfly might just show your trumpets are a bit long now. Usually doesn’t make a sizable difference anyway
I guess we'll see (curious myself). These are 150mm, but I also have 90mm. If I want / need to go taller, I'd need to make them. For testing, I can put spacers under the trumpets I have. If it ends up not making much of a difference, then I'd focus more on aesthetics.
These look like something Dr Seuss would use on a car and apparently they work Image Unavailable, Please Login
