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Daves Other V-twin +Turbo (Drift Quad)


Muncie

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So this thing has been under a sheet since lockdown ended...... well now i have some parts and a little time ive finally finished converting the turbo to run on this engine. Fitted up the aliexpress "cosworth" wastegate actuator which needed some tweaks to get the arm working right. Also took compressor cover off and drilled and tapped a boost signal port into it. 

For first time in a very long time it now has every single bolt back in it. Tick job done. 

Threw factory carb back on and fired her up for first time in ages and made subaru ish spooly noises for my long suffering neighbours. 

20200815_145139.jpg

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awesome toy man! and good to see you realized with the variable vane you have to wind them open a little bit, took me a few days to figure that out on my first variable vane turbo install!

I'm not sure exactly which turbo you are using but i've done draw-through before and learnt a lesson you might be interested in... you need a turbo with carbon seals to do draw through properly, if you use a normal turbo then the vacuum is too high across the compressor when you shut the throttle, and it kills the oil seal after a few hundred km's, however there is abit of info out there saying if you add a second throttle in-line and have it ever so slightly more closed that the SU throttle then it moves the high vacuum area to the first throttle rather than the turbo... I ended up using a SU carb from a mg montego which is factory blow-through after seizing the first turbo running draw-through, no risky fuel pooling in turbo inlet then aswell.

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@drftnmaz Im going to run blow through did think about draw through for about 5 minutes and changed my mind back have come up with a plan to get positive fuel pressure regardless of boost. 

this engine is worth as much as an Ls1 so im inclined to take my time and do everything properly. It'll probably only be used on the beach etc as long as it looks and sounds mental thats all i really care about, however everything will need to work reliably or it'll piss me off. 

At least blowthrough if the turbo gives me grief i can remove it and it'll still run fine.

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Sweet, blowthrough is much better! I found with the blowthrough it didn't like the intake pipe to the carb to be in-line, I ended up using the ulgy boxy thing off the mg factory setup, it changed the airflow path and had slots around the side, I dug it out and took a pic for you, I might strip it down later and get a pic of the inside... when I later changed to the downdraft Aisan factory turbo carb from a daihatsu charade I added a plenum box on the top and also had a diffuser plate on the inlet117818398_1074858316245152_6629509702894647967_n.jpg.5248f4618324a08b26b26279678c160b.jpg117444683_314415859880677_2710457942276031229_n.jpg.913eaae259f270cb7c12121b6b364e00.jpg

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On 16/08/2020 at 15:00, drftnmaz said:

Sweet, blowthrough is much better! I found with the blowthrough it didn't like the intake pipe to the carb to be in-line, I ended up using the ulgy boxy thing off the mg factory setup, it changed the airflow path and had slots around the side, I dug it out and took a pic for you, I might strip it down later and get a pic of the inside... when I later changed to the downdraft Aisan factory turbo carb from a daihatsu charade I added a plenum box on the top and also had a diffuser plate on the inlet117818398_1074858316245152_6629509702894647967_n.jpg.5248f4618324a08b26b26279678c160b.jpg117444683_314415859880677_2710457942276031229_n.jpg.913eaae259f270cb7c12121b6b364e00.jpg

That is quite useful those photos have a plan for a "hat" to go on the inlet using a 90mm pipe cap with a bell mouth in it. Might need to re think the bell mouth if the su prefers a more random airflow.

Im running an SU on my other vtwin and its quite frankly bliss over Mikuni's etc can tune it while riding naturally adpirated they like a good slightly restrictive airfilter like a ramflow, wonder if I'll see any tendencies like that running boost.

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Yea the SU's are interesting to get your head around but once you do they are great! things like different oil or springs in the pot etc are great for fine tuning, but hard when rough tuning to know if they are close, also the turbo SU have a needle that was different to all the rest I came across, very thin at lower section and constant taper the whole way, lots of fuel when you need it!

Here's some pics, hopefully they help you in noticing the differences... The 2 things I found that usually limit carb setups are proper spark control and correct fuel pressure.
1.jpg.02831b8842277c37e9eabb5687483fbc.jpg2.jpg.307d3e1ec3e430a4f11ab619ab7ced5c.jpg3.jpg.a6636883b1ea1121942c69e5f2bbd544.jpg4.jpg.a37539bd28dbddffe7cd1da4d97c2170.jpg5.jpg.c7b5a0f73acaada3f172f214bee5e2d9.jpg

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That inlet thing is bloody weird aye? Looks like a huge restriction. Was going to try make something a little funky and compact that enters on an angle to create some swirl without choking the flow to much.

Good to see how that pipe loops back to pressurize the float chamber too, will be running a AN8 line back to the fuel tank to pressurize that too (with a flame trap) so the fuel pump always maintains 2psi pressure over the boost pressure.

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Sparked this up yesterday to try see if i could disable the 3800rpm rev limit as its just annoying and will break stuff as its real course not a smooth soft limit.

However i bunged the hose on the turbo from my shop vac and used it blow a blockage out after i sucked up a sock cleaning my car,

Makes some pressure heaps of flow though not enough to crack the wastegate, getting some load on the engine more fuel and revs it will do some damage to the tyres for sure!

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Going to try the CDI setup off the Lifan yamaha clone i got this week which will definitely work just need to see how i can configure the pick up to work.

Have heard this engine will happily zing to 6000 rpm for short bursts and 5000rpm continuously wont hurt it either.

My smaller twin loves revs i do have to remind myself not to give it to many as it has no governor and a cast iron flywheel.

 

 

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