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 correct 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 intake plenum"
Just want to now what size throttlebody will be appropriate.
Regards Le Roux Breytenbach
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 at lower RPM when the suction is 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, and 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 injectors 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. Even though the wideband is showing a quick lean condition, I've tried riching up / leaning out the mixture at those lower rpm's to no results. Once I get past 1200rpm prop and the engine is starting to breath, no issues at higher powers.
So we tried an experiment while idling and shook the plane left/right, it reproduces 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 raw fuel to make it's way in pass the opening. Drilled a few small holes at the 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 happy 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.
I'm tempted to remove the slide throttle and put in a standard 3" throttle body on my intake 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.?
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