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The Alfarrari. My Ferrari engined Alfa 105 build


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5 hours ago, JV911 said:

That curved piece you made was particularly satisfying to watch. If I was to have my time again, I'd like to be a fabricator.

I am really enjoying learning these new skills, and fabricating is extremely satisfying.

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  • 1 month later...

Hey Jeff, do you tack weld the panel from behind as well. Just asking as I'm making some gear out of sheet metal for a build i'm doing. Never done sheet metal fab before so all a learning curve for me and I'm getting a lot out of your video's.

 

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 Man you got some cojones on ya Jeff!  👏👏👏

Just a question re shortening the plenum. Wouldn't doing that increase torque instead of losing a bit? I only ask, as I've always known with bikes that if you shorten the intakes it does just that, increases bottom end

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1 hour ago, LeeM said:

 Man you got some cojones on ya Jeff!  👏👏👏

Just a question re shortening the plenum. Wouldn't doing that increase torque instead of losing a bit? I only ask, as I've always known with bikes that if you shorten the intakes it does just that, increases bottom end

From what I understand it is the other way (hence why Ferrari made such long runners for the bottom end). That is where the term velocity stacks comes from, where they increase the velocity of the air along the path to the inlet. It swtiches at the top end of the rev range as by then it just needs as much air as it can get. I am definitely not an expert though, just repeating what I have read.

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Jeff, how far above the bonnet does the engine stick out ?

If it's only a couple of mm why not just make a subtle bonnet scoop.

I get you want a sleeper car but seems like a lot of work for only a couple of mm if that's all it is. If it's a lot more then yeah I get what your doing and why.

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25 minutes ago, 3legs said:

Jeff, how far above the bonnet does the engine stick out ?

If it's only a couple of mm why not just make a subtle bonnet scoop.

I get you want a sleeper car but seems like a lot of work for only a couple of mm if that's all it is. If it's a lot more then yeah I get what your doing and why.

Have another look at Part 11 at 11:35.  May answer your question.

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2 minutes ago, 3legs said:

Thanks OZ930. Must have missed that episode.

Yep just a little bit more than a couple of mm😁

Sorry Jeff for doubting you 😂 No tim tams for me tonight.

Could get away with an A9X style bump, but I think engineers frown on them a bit.  Probably get away with a Cortina 6 style “speed bump” if any is needed,  but we will just have to wait and see what the master craftsman comes up with.🤔

or remove the plenums altogether, there is your 60 mm, cut two holes above the intakes and fill with a gauze.  Yeah, I know, no Ferrari stamp.  Would make all those stacks visible.  Downside is that dust, water and all manner of crap getting sucked into an expensive engine, but it would look and sound awesome. 😎. Maybe a similar treatment to the 911 making it all visible and coming up through the bonnet.  Could put Ferrari script on the top, problem solved 😉

Ok, I’ll get back in my box now 😞

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Yeah not a big fan of bonnet scoops especially the A9X ones although they suit the A9X but not other cars.

I just hope Jeff gets it right the first time otherwise it's going to be an expensive exercise.

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5 hours ago, MFX said:

From what I understand it is the other way (hence why Ferrari made such long runners for the bottom end). That is where the term velocity stacks comes from, where they increase the velocity of the air along the path to the inlet. It swtiches at the top end of the rev range as by then it just needs as much air as it can get. I am definitely not an expert though, just repeating what I have read.

So the way I understand it (and could be wrong and happy to be corrected) is like this.  Think of a guitar string.  It oscillates when you pluck it at a certain wavelength/frequency.  Put your finger on the fret closest to the bridge and you get a high noise - the frequency of the string oscillating is higher.  Move your finger down and you get a lower frequency, lower note.  The actual note is a function of the length of the neck and the thickness of the string.  If you don't get the distance right, the note doesn't resonate and sounds crap.

Now onto engines.  Imagine the tube of air going from the top of the intake to the back of the intake valve.  That's your string.  The intake valve bashing up and down on the end of it - that's your pluck.  The column of air will pulse backwards and forth, and when the length of the tube of air is resonating in time with the intake valve opening, it will actually push a bit more air into the open valve than usual.  A bit like two waves stacking up and forcing water further up a beach, as well (to mix metaphors).   The extra effect of the resonant frequency only works depending on the frequency of the valve (a function of rpm) and the width and length of the intake runner. You also get a bit less efficiency when it's not in tune as sometimes the valve might be open at the right time, and sometimes it won't.  So different engines at different rpms have different sweet spots for length.   So race engines have short intakes tuned for max power rpm.  You don't get any effect at lower rpm, so comparatively, the power/torque curve is peakier.   You can improve this with a two-stage intake runner length like in the 360 engine.  Long runner for lower rpm (less valve openings, lower frequency, longer -think finger on the fret down on the neck of the guitar = lower note).  Shorter runner for high rpm (more valve openings, higher frequency, finger right up on the close fret = higher note).  The engine management computer will switch from one to the other at some set RPM, so you get a resonant boost at lower RPM and another at higher RPM = more 'power under the curve' = flatter torque curve and more performance.

The gold standard is a continuously variable intake length - which the LaFerrari has (also on sport bikes).  993 Varioram is similar to the 360 engine Jeff is hacking into in terms of having a short and long runner for different rpm.  The difference in 993 varioram vs non varioram is about 10hp I think? (I forget).  Changing the intake runner lengths will affect at what rpm the intake resonance has an effect.  I think it's beyond any of us to figure it out but we can assume Jeff's engine will be down a few hp when he's done.  Maybe the dyno tuner will eventually be able to figure out based on the curve vs standard where things are missing.

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 Cheers Jeff. Happy to stand corrected.

I'm no expert either, and I'm sure Ferrari might know a thing or two more about that than myself! I only mentioned it, as when I did some drag racing on the bike, we shortened the stacks and it was much better torque off the line.

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On 27/04/2020 at 08:22, MFX said:

From what I understand it is the other way (hence why Ferrari made such long runners for the bottom end). That is where the term velocity stacks comes from, where they increase the velocity of the air along the path to the inlet. It swtiches at the top end of the rev range as by then it just needs as much air as it can get. I am definitely not an expert though, just repeating what I have read.

that's correct
mazda had a bling system where the intake trumpets start long then contract and shorten up in the rev range.. would love it if someone made an aftermarket version

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1 hour ago, clutch-monkey said:

that's correct
mazda had a bling system where the intake trumpets start long then contract and shorten up in the rev range.. would love it if someone made an aftermarket version

Porsche also did similar with the 'varioram' starting in the 993's.

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Loving your work Jeff.

Who said you can't teach an old dog new tricks ( i'm 60 ). I'am learning so much from this build.

Now as a person who has never attempted anything like what you are doing ( i've mainly worked on bikes over the years although I did restore my 911E ) I have a really. really dumb question for you.

Do you think you have enough room for any movement of the engine and gearbox when you are giving it the berries?

The only reason I ask is I have vivid memories of when I took a Lotus Espirit for a drive back in the early 80's and everytime I changed gear (when putting the boot into it) it felt like the engine was trying to eject itself out of the engine bay. Was very disconcerning.

Anyway I guess you have already figured that out and if you have then I will send myself to the naughty corner (again) for doubting you 🤣

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