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Jul 15, 2016 22:47:40 GMT
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Hi folks, building a new project engine with an eaton blower, megasquirt and front mounted air/air intercooler & want to pick your brains on throttle plate position on my last blower project i put the throttle plate on the blower inlet. It worked well but the only problem was the over-run caused by the huge air volume in the intercooler & pipework (i.e. when you take your foot off the throttle the engine runs-on for a 1/2 second as it swallows all the air in the pipework) To avoid that i want to try a setup with the throttle on the plenum intake, so the blower intake is open & pumping air mass all the time & a seperate bypass butterfly in front of the throttle vents the air when there's no load and progressively closes as load increases. I see on MX5 blower conversions folks are running both types, throttle downstream & upstream, mainly upstream. Does anyone here have experience running the throttle downstream with a rootes blower?  |
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Jul 16, 2016 15:40:26 GMT
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I've used it both ways, at the moment I have it the same way you want to do it. You can pipe the vent back into the intake side of the supercharger.   |
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Last Edit: Jul 16, 2016 15:46:16 GMT by claymore
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Jul 16, 2016 16:00:44 GMT
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says something when Rotrex won't warrant their units when used on a suck through setup rather than a conventional blow through with a blow off valve.
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Last Edit: Jul 16, 2016 16:01:32 GMT by welshpug
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froggy
Posted a lot
Posts: 1,099
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Jul 16, 2016 18:16:42 GMT
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I would have the bypass and bov close to the charger rather than the throttle . I had twin throttles on my compound charged set up with a bypass on the charger which worked well and is commonly done on mx5 builds . Compressed air trying to go backwards through a rootes blower will wear the rotors pretty quickly if the bov and bypass don't work quickly so the closer to the charger the better
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Jul 16, 2016 21:40:13 GMT
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Thanks for replies folks, there's a great wealth of experience on this forum & i appreciate the sharing so i'll try something like this & see how it goes  |
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Jul 24, 2016 19:15:21 GMT
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You want your BOV as close to the throttle as possible and apart from that you're fine. Throttle at the entrance to the plenum is what you want.
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Nathan
Club Retro Rides Member
Posts: 5,649
Club RR Member Number: 1
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Jul 26, 2016 10:26:57 GMT
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Mines in the standard location, with the BOV just after the charger.
When starting my build I looked at the MX guys and then asked BlownIMP (James) of this very forum, who advised me not to bother with the dual TB setup and stick with the standard location etc.
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hario
Part of things
S202 C300STD
Posts: 421 
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Hi folks, building a new project engine with an eaton blower, megasquirt and front mounted air/air intercooler & want to pick your brains on throttle plate position on my last blower project i put the throttle plate on the blower inlet. It worked well but the only problem was the over-run caused by the huge air volume in the intercooler & pipework (i.e. when you take your foot off the throttle the engine runs-on for a 1/2 second as it swallows all the air in the pipework) To avoid that i want to try a setup with the throttle on the plenum intake, so the blower intake is open & pumping air mass all the time & a seperate bypass butterfly in front of the throttle vents the air when there's no load and progressively closes as load increases. I see on MX5 blower conversions folks are running both types, throttle downstream & upstream, mainly upstream. Does anyone here have experience running the throttle downstream with a rootes blower? The BOV needs to be as close to the throttle plate as possible, as the throttle plate is the blockage and the air in the system is still travelling at high velocity towards it, read any forced induction power tuning book and it will tell you that.
Why retain the bypass valve? Eaton's come with a bypass valve in OEM applications because they use mass airflow measurement and cannot 'loose' any of the air mas otherwise the ECU doesn't know how much air is going in (results in a rich condition).
You need a big chav 'dump valve' although a recirculating one would be much quieter, recirculating to the airbox, although you're recirculating really hot air upstream of the compressor = bad.
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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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Aug 11, 2016 19:33:43 GMT
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You need a big chav 'dump valve'
Awesome! Is this big enough... thanks for the replies, i'm digesting it all & re-reading A G Bell's F/I book  |
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hario
Part of things
S202 C300STD
Posts: 421
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Aug 14, 2016 16:27:31 GMT
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You need a big chav 'dump valve'
Awesome! Is this big enough... thanks for the replies, i'm digesting it all & re-reading A G Bell's F/I book Lol, that looks like a Cosworth Indycar V8..
I actually recently discovered the recirc/bypass butterfly on an Eaton blower is actually because the boost produced at idle makes for difficult/bad idle fuel metering, so it uses a vacuum actuator to always be open at idle to setup idle fuelling as per a NA setup..
Probably even more critical with a carburettored/carburated(?) build with manifold referenced rising rate fuel reg. to the bowl! Food for thought..
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Last Edit: Aug 14, 2016 16:28:32 GMT by hario
*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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