I'm just starting my hot rod Mini project, where I'm mounting a 2L Ford Ecoboost in the rear of a classic Mini, so many of these design and engineering choices will apply to me as well as I also want the car to be livable, so keep the ideas flowing guys!
Now, back to your regularly scheduled posts
MiniDave said:I'm just starting my hot rod Mini project, where I'm mounting a 2L Ford Ecoboost in the rear of a classic Mini, so many of these design and engineering choices will apply to me as well as I also want the car to be livable, so keep the ideas flowing guys!
Now, back to your regularly scheduled posts
You're a man after my own heart. Before deciding to sell it, I was going to do something very similar to a Yugo. I decided to sell the Yugo before I got started on the project because I wanted a "simpler" project. At least the X is already mid engined, so the suspension hard points are already there--and that takes a lot of cipherin' out of the project for me.
After doing some math today, I have realized that the exhaust option involving David Vizard's termination box with two 2.25" pipes exiting the box might be the best way to go. Now I need to determine whether two Dynomax Turbo mufflers would support the CFM needed (440 each) for the zero loss system, or if I would need straight-through mufflers.
I wrote to Mr. Vizard on the subject of the exhaust system to ask for his input. I know that he is very busy, so I am skeptical that we will reply. But maybe, if nothing else, my email will prompt him to make a follow-up to his zero loss sound legal exhaust video. I think that his video is geared toward builders of NA V8 engines.
Below is the text of the email:
Dear Mr. Vizard,
I am aware that you are a very busy man and probably receive many inquiries. I do not mean to impose on your time, but I would appreciate some advice if you are willing to share it.
I have watched your very informative YouTube video on the subject of your zero loss exhaust systems, but I have some questions that are not addressed in the video. The questions are listed below. For the record, I am building a turbocharged four cylinder engine and aiming for 400HP, and would like the exhaust to be as free-flowing as possible while remaining civilized with minimum possible drone. The car is also mid-engined and small (FIAT X1/9,) so total exhaust length and space available to build the exhaust system is not unlimited.
1) You say in the video that the pressure wave termination box needs to be eight times the volume of one cylinder. Is it eight times because you primarily address builders of V8 engines, or would eight times also apply to, say, a four cylinder engine? Does turbocharging affect termination box size since each exhaust pulse will be larger than it would be from the same engine without a turbocharger, or is box size strictly determined by cylinder volume? By the math, a 2L I4 engine would have a termination box of a mere 4L (.5*8,) which seems very small. (I’m imagining a gallon milk jug, 3.8L.)
2) Do all of the zero loss principles apply in the same fashion to a turbocharged engine, or do some principles change, or does your termination box not apply at all to a turbo engine?
3) At one point in the video, you refer to the termination box as a resonator. My understanding is that the purpose of the box is to simulate the end of the exhaust collector pipe, but does the box also serve as a resonator? If it does, is it effective at controlling drone, and are there ways in which a layman can optimize the box for eliminating drone?
4) Are there any performance or resonating advantages or disadvantages to manipulating the proportions of the box, or to placing the outlet pipe(s) on any wall other than the wall opposite the inlet pipe? In my situation, it might be more expeditious from a packaging standpoint to place the inlet and outlet on the same side or on adjacent sides.
5) Would it be harmful to power to direct the wastegate discharge pipe into the termination box?
6) As I have mentioned, eliminating the bassy drone have experienced with large tubing is very important. Your guideline of 2.2CFM per open header horsepower and 115CFM/in2 of tubing suggests that I could build a near zero loss system with dual 2.25” pipes exiting the termination box. A single 3” is also adequate, but would provide slightly less flow than two 2.25” pipes assuming that the mufflers selected flow as well as open pipe. Do you believe that a dual 2.25” system after the termination box would be a quieter option than a single 3”?
7) My understanding is that you had a hand in developing the muffler technology that led to the Walker-Dynomax Super Turbo mufflers. I have used these mufflers on NA engines many times and have always liked the sound. Dynomax advertises “up to 700CFM” on every Turbo muffler on their website. Of course, “up to” means anything from 0-700. I highly doubt that a 2” Turbo muffler flows anywhere near what a 3” Turbo muffler flows. I have written Dynomax for flow numbers on individual Turbo muffler part numbers, but the answer was that they did not have that information. I know that you have flow tested mufflers. Do you believe that I could build a zero loss system with a termination box and parallel 2.25” Turbo mufflers, or would I need something that flows more freely?
8) Last question. This is regarding what the termination box does and why it exists. I understand that a reversion wave starts at the end of the collector (or at the entrance of the termination box) and runs back up the system. What is the effect of sending that wave back up the system close to the head vs at the tailpipe? I assume that the wave is going to happen regardless and cannot be prevented, so I speculate that the wave might be causing backpressure and that giving it a shorter path before it dissipates eases backpressure on the overall system.
MiniDave said:I'm just starting my hot rod Mini project, where I'm mounting a 2L Ford Ecoboost in the rear of a classic Mini, so many of these design and engineering choices will apply to me as well as I also want the car to be livable, so keep the ideas flowing guys!
Now, back to your regularly scheduled posts
A couple of notes regarding your project, or at least insights and decisions/plans from my aborted Yugo project:
1)Mid engine cars seem like they would handle great by nature, but it actually takes a lot of engineering to make them handle well/in a way that doesn't constantly try to kill you. Because I am not an engineer and prefer to build things once and be done, I was going to copy a proven design's geometry. I was looking at MR2 geometry, which would not be difficult to reproduce, and X1/9 geometry, which would be easy to reproduce but required that I inherit the X's expensive ball joints. Both are well-proven rear suspensions. I had settled on X1/9 to simplify the project and keep both ends natively 4*98mm on the hubs. I was planning to keep the Yugo front suspension. Since you are starting with a Mini, you probably aren't interested in saving any of the suspension, and are probably going with a tubular frame on which you will install the body.
2) I was planning to build a tunnel-mounted fuel tank (with an enlarged tunnel, of course) in the way that the MR2s did it in an effort to have *some* front stowage under the hood. I'm pretty sure that I could build a 10 gallon tank, which is enough for the car's purpose. If I were to decide that I couldn't make that work, I would build/buy a front fuel tank as I am doing in the X now.
Thanks for the input!
Did you see the K20 powered X1/9 sold on BaT today for *gasp* $40K!!!!
MiniDave said:Thanks for the input!
Did you see the K20 powered X1/9 sold on BaT today for *gasp* $40K!!!!
I feel like there have been 3 this year (k20 x1/9 on bat) and they all sold for 35-45k!
Edit, I guess only 2, but I really feel like I saw a third one for for 30+ somewhere else too.
I'm also building a k20 powered X. I'm very interested in your ideas, as they are similar to mine. I've purchased the axles and shift cables from Matt, but I'm thinking about doing the motor mounts differently from Midwest. My car isn't going to be as radical as yours, but I'm looking forward to a little more power than the original tired 1300. I'm interested in your shifter, care to elaborate? PM me if you are selling yours as I'm interested. And I'm also interested in your thoughts about the muffler situation, can you elaborate on the sound of the conversions you've done? Also you touched on the brake mods, what changes would you make? I'm going the wilwood way, however I think I'm going to use the Abarth 500 front rotors and wilwood 4 pot calipers at all 4 corners and use different size masters with a balance bar for final balancing. Does midwest use the stock clutch master with the Acura slave, or do they use Acura right through? Sorry for all the questions but you're the man to ask. Cheers, Richard
In reply to Alfagtv6 :
I don't have many answers for you but I'd like to see your build thread!!
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