That is a thought, but the area where the whole thing would become unstuck is the curved surface. It would be tricky to form up a folded section that is curved for me. I think I'll carry on how I am currently going. An alternative could be to stitch weld in some thin sheet metal across all gaps and then bog it so it all blends. At this stage, i'm still leaning towards fibreglassQuote:
Originally Posted by Skiboy
I'm not very familiar with automatic transmissions to be honest. I've always had manual cars, this is the first auto. To illustrate the point, when I pulled the engine out, I was told to make sure to unbolt the torque converter before pulling the motor out. So I proceeded to to remove all the bolts along the circumference of the flex plate. Later when I had the engine half out, to my horror I saw the torque converter coming with it! Turns out I unbolted the ring gear!Quote:
Originally Posted by Skiboy
I did have a read through your build thread (nice work by the way), and I did notice the tips you mentioned. Would have been nice to know about the purpose of the hole before I pulled the engine out! Anyway, such is life.
Back to the build:
Over the last couple of days, I've been spending time trying to figure out what size turbo I should start looking for. First I went about trying to figure out what volumetric efficiency I should be using.
Obviously it is known that 2 valve engines typically have a volumetric efficiency of around 80%. But I knew that volumetric efficiency changes with RPM. After doing quite a bit of searching around the internet I found a couple of references that indicated that an engine's torque curve closely follows the volumetric efficiency (Not2Fast: Turbo Glossary). So I went off to find some dyno curves of rover v8s. Below is what I found:
Rolling Thunder - TVRs on the Dyno
https://www.aulro.com/afvb/images/im...012/12/339.jpg
Tuning the Rover V8
https://www.aulro.com/afvb/images/im...012/12/340.jpg
In the above two instances used maximum torque to be 4,000rpm and I made this the 81% point. And then scaled it from there according to the curve.
The problem I had with the above was that the volumetric efficiency went down with reducing RPM and this didn't make any sense to me. So I looked around some more and I found that torque reduces with RPM because of the geometry of the engine being tuned in certain ways, more heat being soaked into the block and the rate of combustion of the gas. That all made sense to me (info from Why Does the Torque Curve Drop Off at Low RPM in a Typical Piston Engine?)
So I looked around some more and then found this:
ScienceDirect.com - Fuel - Alternative fuel and gasoline in an SI engine: A comparative study of performance and emissions characteristics
https://www.aulro.com/afvb/images/im...012/12/341.jpg
The diagram above confirmed my suspicion that volumetric efficiency remained approximately constant at lower RPMs. So I then used the following as my Volumetric Efficiency Table:
1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000
81.00 81.00 81.00 81.00 81.00 81.00 79.16 77.32 73.64 68.00
I could be a little ambitious by using 81%, but anyway.
I used the excel sheet on this website (which is an excellent reference by the way):
Chevy Twin Turbo Project - Reading Compressor Maps and Selecting a turbo
And with some adjustment I got the following:
https://www.aulro.com/afvb/images/im...012/12/342.jpg
The values were cross checked with this calculator, and seemed to be agreeing with each other:
Not2Fast: Turbo Calculator
I then spent some time checking through what possible garett turbos could be used and below are the results:
https://www.aulro.com/afvb/images/im...012/12/343.jpg
https://www.aulro.com/afvb/images/im...012/12/344.jpg
At first it looks like the GT1548 is the best candidate as the curve starts nice and early and the points are close to the peak efficiency. However, when you look at the efficiencies you find that it is a very low efficiency compressor 68-72%.
So perhaps the GT2052 52 Trim is the better option as its efficiencies are in the region of 74-77%.
It would be great if anyone can confirm i'm doing this the right way. Because I've never done any of this before so I could be doing something wrong somewhere.
