hario
Part of things
S202 C300STD
Posts: 421
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Jul 11, 2017 15:19:27 GMT
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Good afternoon Sirs
This is a placeholder for a Honda CB350 Four turbo build I'll be helping my cousin build..
After convincing him to build a blow through setup with an air/water charge cooler to keep the no-radiator look of the air cooled engine, (likely excluding a small oil cooler, with the possibility of positioning the charge cooler water rad under the seat), where we'd wrap more coils on the stator to provide more power available for the high pressure fuel pump and charge cooler circulation pump, I'm now convincing him that revision #1 should be a draw through design for ultra simples... While we build a blow through setup on the bench, SO:
The Honda CB### four and twin range use a centrifugal timing advance mechanism on the end of the crank, or I think on the end of one cam on the twin, this is unfortunate as I imagine with a vacuum-advance module on the dissy (as per a-series) I'd convert to pressure-retard to achieve this, by swapping the vacuum module for a small wastegate actuator type affair.
Therefore, at the moment I'd like to request anyone's detail of method of boost-referenced ignition retard, and may I ask how you accomplished this? Without reverting to megajolt..
Convert to pressure advance mechanism? But can't convert the standard ignition/points mechanism easily because it's all spinny spinny inside the crankcase cover..
Locking the timing retarded is too crude as this needs to be able to be driven not full beans all the time, and being 350cc it will really be a more pleasurable drive.
Attached picture of a RayJay off the shelf turbo kit for CB/400/500/750, which we intend to pillage the design of. Nice stealth turbo-under-seat arrangement.
We're looking at a Mikuni 40/44mm slide carb, due to the availability of jets and needles as we're likely to have to try loads to get it set up properly
Beers!
Harold
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Last Edit: Jul 11, 2017 15:26:27 GMT by hario: pics!
*S202 C300TD Wagon* Installed: OM606 & 722.6, Evo6 IC, S600AMG callipers & 345mm rotors. No catz. Leatherish seats.. Rust.. Future: DIY manifolds & turbo compound build. Built IP, & some kind of software. Less rust..
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Hmm, this could be interesting...
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Jul 12, 2017 18:31:25 GMT
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Be sure to use a turbo that is capable of draw-through, it needs to have carbon seals to be able to pressurize the mixture instead of just air. Also, keep the boost low, you do not want to heat a volatile fuel-air mixture and intercoolers are not an option. I would think that a large CV carburettor would be easier instead of the simple non-vacuum pictured, when the turbo comes on boost you need lots of extra fuel which you'll struggle to add manually.
As for the ignition, you'll need to retard it, there's no way around it. Maybe you can fit an entire A-series distributor on the head?
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hario
Part of things
S202 C300STD
Posts: 421
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Jul 17, 2017 17:51:20 GMT
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Be sure to use a turbo that is capable of draw-through, it needs to have carbon seals to be able to pressurize the mixture instead of just air. Also, keep the boost low, you do not want to heat a volatile fuel-air mixture and intercoolers are not an option. I would think that a large CV carburettor would be easier instead of the simple non-vacuum pictured, when the turbo comes on boost you need lots of extra fuel which you'll struggle to add manually. As for the ignition, you'll need to retard it, there's no way around it. Maybe you can fit an entire A-series distributor on the head?
Agreed, but I thought all modern turbo's were sealed this way???
Yes it would be low boost un-intercooled of course because od the draw though, waiting on a Haynes manual to see what stock compression ratio is etc,
We'll use a pitot tube or install a calibrated restrictor ring which the float chamber will reference to provide a enrichment as boost comes on, as per Metro Turbo design,
Ignition locked in retard is too crude so we'll definitely either build a pressure referenced retard mechanism for the points, otherwise we are looking at megajolt, the points can be binned and swapped for a teeny tiny 36-1 wheel.
Why a large CV carb? DO you know what they were fitted to stock by any change??
Beers, H
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*S202 C300TD Wagon* Installed: OM606 & 722.6, Evo6 IC, S600AMG callipers & 345mm rotors. No catz. Leatherish seats.. Rust.. Future: DIY manifolds & turbo compound build. Built IP, & some kind of software. Less rust..
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Jul 24, 2017 11:19:58 GMT
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You could get a large CV carburetor from something like an SR500, a big single. I don't think ALL modern turbos use carbon seals, just be sure to check it before spending the money You don't need a pitot tube or restrictor if you're doing draw through, that's only for blow through applications. Just put a regular carb in front of the turbo and be sure it's jetting for the increased air flow.
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fad
Posted a lot
Posts: 1,781
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Jul 30, 2017 10:11:48 GMT
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On the turbo front...
NO modern turbos use carbon shaft seals. They all use dynamic seals which unseats under negative pressure.
Older turbos that use carbon (many Garret T3) have almost always been rebuilt with dynamic seals in their lives as I found to my repeated cost.
My Volksrod runs a draw through system and I had to rebuild my turbo with carbon seals (easy to do, parts are readily available). But don't waste your time looking for turbos with factory fitted carbon seals, buy the one you want and rebuild it with carbon seals and save the heartache. And, as you know, but to anyone thinking of it do NOT try to run an intercooler with draw through, it does not work and is just dangerous.
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Last Edit: Jul 30, 2017 10:14:25 GMT by fad
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fad
Posted a lot
Posts: 1,781
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hario I have a list of turbos that had a carbon seal from factory if it will help?
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hario
Part of things
S202 C300STD
Posts: 421
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Jul 31, 2017 18:31:45 GMT
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hario I have a list of turbos that had a carbon seal from factory if it will help? Thanks! If it includes small cheap modern turbos that would be useful mate thanks,
After discussions, We are going to use Megasquirt for spark and fuel.. Turns out you can re-wind the stator with more coils to increase the output current, 'hopefully' to support megasquirt ecu and a fuel pump..
I've calculated draw as follows: 4a per coil, 1a per injector, 1a for ECU, 4 for fuel pump = 25a extra current draw which we'd need to add to the CB350 stock stator's output which is circa 8a...
Perhaps we can fabricate an adapter plate to mount a stator from a bigger (cb750?) engine, along with a crank adapter puck of some kind. I've seen the stator binned and a pulley mounted to the crank snub to belt dive an alternator mounted above the gearbox, BMW K75(?) motorbike has a small alt. which may work for this solution. Denso alt. from a Micra would be second choice but quite big.
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*S202 C300TD Wagon* Installed: OM606 & 722.6, Evo6 IC, S600AMG callipers & 345mm rotors. No catz. Leatherish seats.. Rust.. Future: DIY manifolds & turbo compound build. Built IP, & some kind of software. Less rust..
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fad
Posted a lot
Posts: 1,781
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Jul 31, 2017 18:59:15 GMT
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How did you calculate those loads? (Thats not a loaded question, genuinely asking).
Nah nothing modern. Most modern I found was the garret T03 (Saab and the like, low boost). You gotta keep in mind modern turbos are built to be at atmospheric or positive pressure and never ever have fuel in them, so often leak like a sieve cos they don't need to hold down all the pressure since the wastegate / bov / whatever vents the spare puff anyway. You need something old skool with a tight sealed housing else you'll suck unmetered air in at idle and spray fuel everywhere on boost (ask me how I know!), coupled with the damn piston in the dynamic seal unseating every time your butterfly shuts making your intake suck oil down it, you'll never ever get fuelling right, you'll keep going lean yet have inexplicably sooty plugs and it'll smoke like a 2 stroke. I bought a garret, new seals and shut the compressor housing tight with some red locktight stuff that was more expensive per gram than high grade coke but is seemingly everything proof (pressure, fuel, and sticks harder than... Well it sticks hard.)
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Jul 31, 2017 19:46:34 GMT
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How did you calculate those loads? (Thats not a loaded question, genuinely asking). Nah nothing modern. Most modern I found was the garret T03 (Saab and the like, low boost). You gotta keep in mind modern turbos are built to be at atmospheric or positive pressure and never ever have fuel in them, so often leak like a sieve cos they don't need to hold down all the pressure since the wastegate / bov / whatever vents the spare puff anyway. You need something old skool with a tight sealed housing else you'll suck unmetered air in at idle and spray fuel everywhere on boost (ask me how I know!), coupled with the damn piston in the dynamic seal unseating every time your butterfly shuts making your intake suck oil down it, you'll never ever get fuelling right, you'll keep going lean yet have inexplicably sooty plugs and it'll smoke like a 2 stroke. I bought a garret, new seals and shut the compressor housing tight with some red locktight stuff that was more expensive per gram than high grade coke but is seemingly everything proof (pressure, fuel, and sticks harder than... Well it sticks hard.) caughblowthroughcaugh
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Jul 31, 2017 19:47:07 GMT
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hario I have a list of turbos that had a carbon seal from factory if it will help? Thanks! If it includes small cheap modern turbos that would be useful mate thanks,
After discussions, We are going to use Megasquirt for spark and fuel.. Turns out you can re-wind the stator with more coils to increase the output current, 'hopefully' to support megasquirt ecu and a fuel pump..
I've calculated draw as follows: 4a per coil, 1a per injector, 1a for ECU, 4 for fuel pump = 25a extra current draw which we'd need to add to the CB350 stock stator's output which is circa 8a...
Perhaps we can fabricate an adapter plate to mount a stator from a bigger (cb750?) engine, along with a crank adapter puck of some kind. I've seen the stator binned and a pulley mounted to the crank snub to belt dive an alternator mounted above the gearbox, BMW K75(?) motorbike has a small alt. which may work for this solution. Denso alt. from a Micra would be second choice but quite big.
I have a sohc cb750 if you want dimensions of anything.
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fad
Posted a lot
Posts: 1,781
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Jul 31, 2017 19:48:39 GMT
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How did you calculate those loads? (Thats not a loaded question, genuinely asking). Nah nothing modern. Most modern I found was the garret T03 (Saab and the like, low boost). You gotta keep in mind modern turbos are built to be at atmospheric or positive pressure and never ever have fuel in them, so often leak like a sieve cos they don't need to hold down all the pressure since the wastegate / bov / whatever vents the spare puff anyway. You need something old skool with a tight sealed housing else you'll suck unmetered air in at idle and spray fuel everywhere on boost (ask me how I know!), coupled with the damn piston in the dynamic seal unseating every time your butterfly shuts making your intake suck oil down it, you'll never ever get fuelling right, you'll keep going lean yet have inexplicably sooty plugs and it'll smoke like a 2 stroke. I bought a garret, new seals and shut the compressor housing tight with some red locktight stuff that was more expensive per gram than high grade coke but is seemingly everything proof (pressure, fuel, and sticks harder than... Well it sticks hard.) caughblowthroughcaugh Just needs the right fuel pump and carb.
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fad
Posted a lot
Posts: 1,781
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Jul 31, 2017 19:54:42 GMT
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I'm biased though... There's just something about a hashed together draw through on an engine that was never meant for boost using bits out of a scrap bin I love.
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Jul 31, 2017 20:16:02 GMT
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A lashed together turbo system is always fun, don't matter which way you do it.
Everyone makes their choice and goes with it. Blowthrough is maybe a tiny bit harder but really, its just a different set if issues. Both ways bring a smile.
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fad
Posted a lot
Posts: 1,781
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Jul 31, 2017 20:18:38 GMT
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Nah it ain't harder. Just needs a different scrap bin.
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