From: "Le Roux Breytenbach breytenbachleroux@gmail.com" <flyrotary@lancaironline.net>
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Subject: Throttlebody 
Message-Id: <9A6A9F85-70BB-4931-8BF6-96EDF9101439@gmail.com>
Date: Sun, 23 Jun 2019 20:53:19 +0200
To: "Matt Boiteau mattboiteau@gmail.com" <flyrotary@lancaironline.net>


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Hi Matt: You have mentioned in your email to the group about to replaced the=
 slide throttle with a 3 inch throttlebody.Is the 75 mm more or less the cor=
rect size for a p port 13 B ?
I have p ported my housings with 44 mm diameter ports. The intake runners is=
 2 inch to the p ports .Has also build a intake plenum "cilinder shape intak=
e plenum"
Just want to now what size throttlebody will be appropriate.

Regards Le Roux Breytenbach=20

I have a good one for you guys. I've been trying to get a slide throttle to w=
ork. Lots of fixing to make it usable, mainly at lower RPM when the suction i=
s at it's highest. Lapped the outer plates flat, machined down the thickness=
 of the inside slide, doubled up all the bolts to seal fuel from leaking, an=
d stiffened up the throttle cable every few inches. BUT now that I am taxing=
 around, this issue is coming up and I think it has to do with having the in=
jectors before the slide throttle. I think...

When I taxi (under 1100rpm prop) and start to step on the brakes, the engine=
 drops a few hundred RPM and struggles. If I pull power to idle to slow down=
 before tuning (600rpm prop), the engine will die. Unless I catch it in time=
, and stab the throttle. The right brake is more pronounced then the left. E=
ven though the wideband is showing a quick lean condition, I've tried richin=
g up / leaning out the mixture at those lower rpm's to no results. Once I ge=
t past 1200rpm prop and the engine is starting to breath, no issues at highe=
r powers.

So we tried an experiment while idling and shook the plane left/right, it re=
produces the engine dieing. I did see a quick puff of black out the tailpipe=
. That make me think at low idle, with the slide opening moves right to left=
, the fuel is pooling at the bottom of the opening. The shaking is causing r=
aw fuel to make it's way in pass the opening. Drilled a few small holes at t=
he bottom of the slide to hopefully suck in any raw fuel that tries to pool.=
 It's helped a tiny bit, but if I shake the intake, the engine still isn't h=
appy at idle.

I don't have a video of the engine running (will get it tomorrow), but here'=
s a video of the intake setup.
https://youtu.be/tuwBkDuKh9Q

I'm tempted to remove the slide throttle and put in a standard 3" throttle b=
ody on my intake box (ie, before injectors). Just want to get your guy's tho=
ughts if I'm on the right track. And if anybody is running a slide throttle.=
?

- Matt Boiteau

Sent from my iPhone=

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div dir=3D"ltr"><span></span></div><div di=
r=3D"ltr"><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"><div>Hi Matt: You have mentioned in your email to the group about to r=
eplaced the slide throttle with a 3 inch throttlebody.Is the 75 mm more or l=
ess the correct size for a p port 13 B ?</div><div>I have p ported my housin=
gs with 44 mm diameter ports. The intake runners is 2 inch to the p ports .H=
as also build a intake plenum "cilinder shape intake plenum"</div><div>Just w=
ant to now what size throttlebody will be appropriate.</div><div><br></div><=
div>Regards Le Roux Breytenbach&nbsp;</div><span style=3D"background-color: r=
gba(255, 255, 255, 0);"><div><span style=3D"background-color: rgba(255, 255,=
 255, 0);"><br></span></div>I have a good one for you guys. I've been trying=
 to get a slide throttle to work. Lots of fixing to make it usable, mainly a=
t lower RPM when the suction is at it's highest. Lapped the outer plates fla=
t, machined down the thickness of the inside slide, doubled up all the bolts=
 to seal fuel from leaking, and stiffened up the throttle cable every few in=
ches. BUT now that I am taxing around, this issue is coming up and I think i=
t has to do with having the injectors before the slide throttle. I think...<=
/span><div><span style=3D"background-color: rgba(255, 255, 255, 0);"><br></s=
pan></div><div><span style=3D"background-color: rgba(255, 255, 255, 0);">Whe=
n I taxi (under 1100rpm prop) and start to step on the brakes, the engine dr=
ops a few hundred RPM and struggles. If I pull power to idle to slow down be=
fore tuning (600rpm prop), the engine will die. Unless I catch it in time, a=
nd stab the throttle. The right brake is more pronounced then the left.&nbsp=
;<span style=3D"line-height: 1.5;">Even though the wideband is showing a qui=
ck lean condition, I've tried riching up / leaning out the mixture at those l=
ower rpm's to no results. Once I get past 1200rpm prop and the engine is sta=
rting to breath, no issues at higher powers.<br><br></span></span></div><div=
><span style=3D"background-color: rgba(255, 255, 255, 0);">So we tried an ex=
periment while idling and shook the plane left/right, it reproduces the engi=
ne dieing. I did see a quick puff of black out the tailpipe. That make me th=
ink at low idle, with the slide opening moves right to left, the fuel is poo=
ling at the bottom of the opening. The shaking is causing raw fuel to make i=
t's way in pass the opening. Drilled a few small holes at the bottom of the s=
lide to hopefully suck in any raw fuel that tries to pool. It's helped a tin=
y bit, but if I shake the intake, the engine still isn't happy at idle.<br><=
br>I don't have a video of the engine running (will get it tomorrow), but he=
re's a video of the intake setup.</span></div><div><font color=3D"#000000"><=
span style=3D"caret-color: rgb(0, 0, 0); background-color: rgba(255, 255, 25=
5, 0);"><a class=3D"m_-2880230406433127638m_2430937082685005108m_-4724544621=
628724628yiv1995370028moz-txt-link-freetext" href=3D"https://youtu.be/tuwBkD=
uKh9Q" rel=3D"noopener noreferrer noreferrer noreferrer noreferrer" target=3D=
"_blank">https://youtu.be/tuwBkDuKh9Q</a><br><br></span></font></div><div><s=
pan style=3D"background-color: rgba(255, 255, 255, 0);">I'm tempted to remov=
e the slide throttle and put in a&nbsp;<span style=3D"line-height: 1.5;">sta=
ndard&nbsp;</span><span style=3D"line-height: 1.5;">3" throttle body on my i=
ntake box (ie, before injectors). Just want to get your guy's thoughts if I'=
m on the right track. And if anybody is running a slide throttle.?</span></s=
pan></div><div><div><span style=3D"background-color: rgba(255, 255, 255, 0);=
"><br></span></div><div class=3D"m_-2880230406433127638m_2430937082685005108=
m_-4724544621628724628yiv1995370028mb_sig"><span style=3D"background-color: r=
gba(255, 255, 255, 0);">- Matt Boiteau</span></div></div><br><div id=3D"Appl=
eMailSignature" dir=3D"ltr">Sent from my iPhone</div></div></body></html>=

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