Build Thread: Restoration and New School V8, Photogrammetry: Pics to CAD |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Build Thread: Restoration and New School V8, Photogrammetry: Pics to CAD |
Joemo5 |
Apr 5 2018, 12:07 AM
Post
#1
|
Member Group: Members Posts: 54 Joined: 1-April 18 From: Charlotte, North Carolina Member No.: 22,011 Region Association: South East States |
I probably should have joined 914world and started posting earlier but I have been reading and learning ALOT about these cars already from whats posted in other threads. For that, I thank you guys. I have some catching up to do. Heres my story.
I picked up my first 914 a few months ago as a project car that could eventually serve as a track car or weekend toy. Out of the many different types of cars that would make cool projects, I ended up with the 914 in my crosshairs after I discovered that not only they were mid engine but v8 swaps where not uncommon. Other factors include I had never came across one in the wild, which makes them rare to me. I also like the idea of following in my fathers footsteps with a mid engine european car. He had a Lotus Europa in is 20's. Jumping back the v8 idea though, the added weight of a more powerful drivetrain is at the center of the car, meaning there is a minimal increase in the rotational moment of inertia: the car should retain it's handling characteristics better than a v8 swap in a comparable sized car with a forward mounted engine. After investigating several craigslist ads that turned out to have missing titles, a friend pointed me towards a local Porsche shop that was known for 914's. Bingo. More 914's than I expected. A few short conversations led to a cheap car that needed some work and was up for grabs. Heres what the '75 2.0l car looked like prior to being yanked out of the weeds. On the trailer headed home Some of my buddies and I broke out a pressure washer and the car looks good for sitting outside for a year or two. The car did not have the original engine or trans installed when purchased. Although, they were included in the sale. Some tinkering around got some of the electronics working off a jump start box Now heres the fun part. A month or two later, I came across a craigslist deal that would add some originality to the project. An 5.3l L83 out of a 2015 silverado with only "15,000" miles for $1200. Would an engine with 15,000 miles still have the assembly grease in between the rocker and top of the valve? (IMG:style_emoticons/default/confused24.gif) For those of you unfamiliar with this engine: It's NOT an LS, its part of the EcoTec Gen V family. The next generation of Chevy v8 that shares some of the architecture with the LS but with direct injection and variable valve timing. Also its an aluminum block which is different from the Gen IV 5.3 truck blocks which were cast iron. Rumor has it that GM is offering a stand alone kit for the gen V engines which, while costly, would simplify the install a lot. Quick specs: Stock 380hp and 416 ft-lbs on e85 fuel. 11.0:1 compression ratio ~400lb dressed. Anyone know how much the original 2.0l engine weighs? At this point I'm sure most of you have thought: "What does the hell hole look like?" The rot is the worst of all the ones I have viewed online. The only saving grace is that after selling the original motor, trans and wheels, I have made back the purchase price of the car and have a few bucks in my pocket. I have some experience in fabrication and plan on being a sheet metal pro by the end of all this. Heres a shot of the floor pans and fire wall area. At this point the car is stripped and ready to be mounted on a rotisserie. Lots of bracing prior to mounting on the rotisserie of course. I have more pics and more details but that should do for now. Attached image(s) |
Joemo5 |
Apr 8 2018, 11:42 AM
Post
#2
|
Member Group: Members Posts: 54 Joined: 1-April 18 From: Charlotte, North Carolina Member No.: 22,011 Region Association: South East States |
I have been tied up doing transmission repairs on my daily, a 06 Subaru LGT. So in the mean time I've been playing around with an excel sheet left over from a college assignment. The idea being to get an idea of how the Boxster gearing plays out with a 914 and 5.3L EcoTech. Hopefully, the screen shots are legible.
Here are my inputs. Note that the 7000 rev limiter is high. Realistically, 6500 would be a better limit point with valve spring and push rod changes for the 5.3L to live happily. I pulled my torque data from the stock graph shown here 2014-2016 CHEVY/GMC SILVERADO/SIERRA 5.3L 1500 TEXAS SPEED & PERFORMANCE L83TR-2 CAMSHAFT Plotted my points and calculated and equation Found gear ratio's for the G86.20 trans from here PORSCHE 986 BOXSTER TRANSAXLE SPECIFICATIONS Below shows engine speed in each gear. Note this is for a rear 275/40R17 tire. (flares are definitely in my future) The blacked out area's are above the rev limiter or below idle. Using the equation calculated above and the gearing for the G86.20 determined the force the tire could potentially exert on the road in each gear "tractive force". I then used the drag coefficient and frontal area found in this link... Cassidy-Online Areodynamic Aids ... to determine aerodynamic drag for the range of speeds shown. Note the drag coefficient and frontal area are for a narrow body car without a spoiler or front splitter. So realistically, I imagine the drag force would be higher. I also calculated a force induced by rolling resistance of the tire for range of speed shown. However, I feel less confident in that calculation but figured it plays a role so I included it. Below is a graph of "resistive force" (areo + rolling resistance) and "tractive force" in each gear shown in the Y axis and speed in the X axis. Subtracting the resistive forces from tractive forces gives an overall force applied to the car causing acceleration. Using the weight of the car (~2300lbs) you could come up with an acceleration in G's shown below in each gear, at each speed. Again, blacked out area's are either above 7000 rpm or below idle. It's probably worth taking all this with a grain of salt.. there are a million and one variables not included that could affect any of the above. The car probably won't accelerate at 2G's either. More likely is a smoke show and a slightly smaller tire diameter. (IMG:style_emoticons/default/aktion035.gif) |
Lo-Fi Version | Time is now: 11th June 2024 - 03:05 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |