CharlesZ
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| posted on 30/8/15 at 06:10 PM |
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A few questions about how VVT works and do bike engines have this feature? [Hydrogen Locost]
Hi a friend (that's busy doing a chemistry degree) and I are looking at building a hydrogen powered Locost. We've been doing lots of
research and reading but I have a few questions since I've never really delved this deep into the workings of engines and I don't really
have any experience with BECs.
- We need to keep the engine size small for the first build (there may or may not be more builds depending on how well it works) because the main
purpose of the first build is just to prove it works. We are aiming for a 1000cc engine. VVT and direct injection are both features that are necessary
in our project. Am I correct in saying that car engines of this capacity will not have these features but bike engines will?
- Do bike engines always come as a bundled unit with a gearbox?
- We are going to be using a very high A/F ratio (in the low-mid 30s). Are lambda sensors on ECUs interchangeable? The reason I ask is because a good
ECU that I looked at has a lambda sensor that maxes out at less than half our fuel ratio so I'm going to look for one that doesn't max out
(if such a thing exists, otherwise I'm not sure what I'll do) although it does seem like most of them don't mention the range of
what they can measure.
- How "variable" is variable valve timing? We're going to need to play around quite a bit with the valve timing to get optimal
results. Am I correct in saying that you can't adjust each cylinders valves opening and closing times? If so then how exactly can you vary the
timing?
- What's the cost of a BEC setup vs a CEC setup?
- How does a bike engine connect to the drive shaft? Or are they mounted in the rear, directly on the rear wheels' axel?
- Would the hardest part of a CEC to BEC project be the part of welding the new engine mounts?
Thanks a lot, any help is greatly appreciated.
[Edited on 30/8/15 by CharlesZ]
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Nickp
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| posted on 30/8/15 at 06:33 PM |
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Bikes don't generally have VVT as they don't need the torque (it's all about revs). Only one I can think of is the VFR800 vtec.
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sdh2903
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| posted on 30/8/15 at 06:35 PM |
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1000Cc ford ecoboost has vvt and direct injection. Not sure if the small matter of the turbo will scupper your plans?
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CharlesZ
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| posted on 30/8/15 at 08:27 PM |
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Thanks for the replies guys. I've spoken with my friend and he says it won't be an issue if we need to go for a bigger engine.
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MikeRJ
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| posted on 30/8/15 at 09:23 PM |
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The largest capacity bike engine with some form of variable cam timing that I can think of is the Kawasaki 1400GTR. There's also talk that
Suzuki will be introducing VVT on next years DL1000 (1 litre V-twin).
However, there are numerous different versions of variable valve timing and they aren't all as good as each other. Many engines just have a
dephaser pulley on the inlet cam (or sometimes exhaust and inlet) so that the relative timing can be adjusted (and therefore valve overlap), but valve
lift and duration is fixed by the cam lobe. Some like Honda's VTEC and Toyotas VVTL-i switch between two different cam lobe profiles, which
works well but isn't very 'variable' as it's either on or off.
One of the cleverest systems is Rovers VVC as used on the more powerful 1.8L K series engines which provided stepless control of the inlet cam
duration over a very wide range (220 to 295 degrees).
[Edited on 31/8/15 by MikeRJ]
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alex1991
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| posted on 30/8/15 at 10:58 PM |
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The Honda iVTEC is quite adaptable and can be controlled via aftermarket ecu.
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snapper
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| posted on 31/8/15 at 07:02 AM |
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AF of 30?
What fuel are you running?
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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loggyboy
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| posted on 31/8/15 at 07:36 AM |
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A few different types of vvt. As mentioned above, honda uses different profiles of lobe and changes more than just timing, the rover vvc controls each
inlet valve separately and is very complicated. The renault dephaser system is an oil fed pulley that contols whole inlet cam. For simplicity of
renault system it's pretty effective, 200bhp from 2.0. But I am bias!
Mistral Motorsport
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drt
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| posted on 31/8/15 at 09:03 AM |
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1 as stated, not many bikes with vvt, direct injection has not yet been applied to motorcycles 
In fact, I am struggling to think of an engine who has both... cheapest direct injected engine would be a Mitsubishi GDI (carisma,...)
2 Yes they do, only the older bikes (until +- 1960s) Some Royal Enfields and Harleys come with a transmission unit.
although there is a kit to convert a Hayabusha to skip the gearbox and bolt it to an MX5/Miata gearbox
3 Even so called 'wide-band' lambda sensors only go up to 25:1, you'll need some very specific kit to achieve 30:1...
4 All the VVT systems control all the cylinders at once, individual valve control you're looking at pneumatic F1 style actuation... :p
Then most standard VVT control the intake camshaft only
How "variable" is variable valve timing? We're going to need to play around quite a bit with the valve timing to get optimal
results. Am I correct in saying that you can't adjust each cylinders valves opening and closing times? If so then how exactly can you vary the
timing?
5 CEC will be cheaper, les engineering required and more robust
6 In a seven style Lowcost ? An adapter is fitted to the longitudinally mounted bike engine. This adapter fits on the sprocket-shaft and connects to a
prop-shaft that goes all the way back to the diff.
Mid engine cars often have a car diff converted to chain drive
7 BEC= new engine mounts + new prop shaft (make or buy) + adapter (make or buy) + gear linkage.
I would figure the Hydrogen part as the hardest… easily
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drt
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| posted on 31/8/15 at 09:07 AM |
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quote:
Originally posted by loggyboy
A few different types of vvt. As mentioned above, honda uses different profiles of lobe and changes more than just timing, the rover vvc controls each
inlet valve separately and is very complicated. The renault dephaser system is an oil fed pulley that contols whole inlet cam. For simplicity of
renault system it's pretty effective, 200bhp from 2.0. But I am bias!
I thought the Rover K VVC controlled 2 cylinders at the time ?
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jambojeef
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| posted on 31/8/15 at 09:30 AM |
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http://www.vgkracing.com/k%20engine%20EU3.pdf
description on p18
technically it has 4 inlet camshafts - its not that complicated to understand but actuation might be tricky on an aftermarket ECU.
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MikeRJ
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| posted on 31/8/15 at 10:09 AM |
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quote:
Originally posted by jambojeef
http://www.vgkracing.com/k%20engine%20EU3.pdf
description on p18
technically it has 4 inlet camshafts - its not that complicated to understand but actuation might be tricky on an aftermarket ECU.
The VVC actuation is no more difficult than properly controlling e.g. the VVT on the Ford ST170 engine which is supported by many aftermarket ECUs.
The ECU just measures the phase difference between the crank and cam, and adjusts one solenoid to achieve a target value.
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Ivan
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| posted on 31/8/15 at 11:44 AM |
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Maybe a dumb comment but don't Lambda sensors measure available O2 after combustion and thus equate it to air fuel ratio - if that's the
case it should be relatively easy to re-calibrate the gauge readings to your actual AF ratio. Multiplying by 2 would turn 14.7 to 29.4 AFR on the
gauge which seems to be your stochiametric aim.
I assume in stating the above that stochiametric burn whatever the fuel would leave roughly the same amount of free oxygen in the exhaust so if that
assumption is correct your chemical friend could easily create a correction curve to correct the gauge.
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jambojeef
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| posted on 2/9/15 at 04:56 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by jambojeef
http://www.vgkracing.com/k%20engine%20EU3.pdf
description on p18
technically it has 4 inlet camshafts - its not that complicated to understand but actuation might be tricky on an aftermarket ECU.
The VVC actuation is no more difficult than properly controlling e.g. the VVT on the Ford ST170 engine which is supported by many aftermarket ECUs.
The ECU just measures the phase difference between the crank and cam, and adjusts one solenoid to achieve a target value.
That's interesting Mike - are the target values published somewhere youre aware of out of interest?
Geoff
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CharlesZ
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| posted on 2/9/15 at 06:35 PM |
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quote:
Originally posted by snapper
AF of 30?
What fuel are you running?
Hydrogen 
Is it possible to reply to multiple posts at once on this forum?
[Edited on 2/9/15 by CharlesZ] Why will it not display the smiley next to my first line of the reply?
[Edited on 2/9/15 by CharlesZ]
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CharlesZ
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| posted on 2/9/15 at 06:40 PM |
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quote:
Originally posted by drt
7 BEC= new engine mounts + new prop shaft (make or buy) + adapter (make or buy) + gear linkage.
I would figure the Hydrogen part as the hardest… easily
Luckily I've got a friend that's doing a chemical engineering degree to help me.
How much pressure would you guys think is a good amount to allow from the hydrogen storage system into the fuel lines?
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CharlesZ
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| posted on 2/9/15 at 06:42 PM |
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quote:
Originally posted by Ivan
Maybe a dumb comment but don't Lambda sensors measure available O2 after combustion and thus equate it to air fuel ratio - if that's the
case it should be relatively easy to re-calibrate the gauge readings to your actual AF ratio. Multiplying by 2 would turn 14.7 to 29.4 AFR on the
gauge which seems to be your stochiametric aim.
I assume in stating the above that stochiametric burn whatever the fuel would leave roughly the same amount of free oxygen in the exhaust so if that
assumption is correct your chemical friend could easily create a correction curve to correct the gauge.
Is the limitation not in the ECU, rather than the actual sensor? Anyone know which one it is?
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CharlesZ
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| posted on 2/9/15 at 06:59 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by jambojeef
http://www.vgkracing.com/k%20engine%20EU3.pdf
description on p18
technically it has 4 inlet camshafts - its not that complicated to understand but actuation might be tricky on an aftermarket ECU.
The VVC actuation is no more difficult than properly controlling e.g. the VVT on the Ford ST170 engine which is supported by many aftermarket ECUs.
The ECU just measures the phase difference between the crank and cam, and adjusts one solenoid to achieve a target value.
Ah, thanks. I'm looking at the 1l ford ecoboost which has a solenoid for the VVT for each cylinder. I'm wondering if/where I'll be
able to find an ECU that will be able to work with it.
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CharlesZ
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| posted on 2/9/15 at 07:01 PM |
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quote:
Originally posted by jambojeef
http://www.vgkracing.com/k%20engine%20EU3.pdf
description on p18
technically it has 4 inlet camshafts - its not that complicated to understand but actuation might be tricky on an aftermarket ECU.
Yeah, this is what I'm stressing about because I really want to be able to make the Ford Ecoboost 1l work in this build but that seems to be an
issue.
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