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1993 to 2012 Cadillac 4.6L V8 NorthStar eng. T-body, very high quality, 3 inch dia., sealed ball bearing plt. pivots, easy to clean up and block the bypass, at this point should be VERY cheap at salvage yard. I think all our build photos from that far back are on disk up in my office somewhere. David R. Cook RV6A Rotary On June 24, 2019 at 1:14 PM "Charlie England ceengland7@gmail.com" <flyrotary@lancaironline.net> wrote:
An early '90s Ford Mustang 3.0 HO V-8 has a ~70mm throttle body. There used to be a lot of them on ebay for nearly free, and they're really easy to strip to almost no weight. Total area is almost exactly equal to a 4-port Renesis total intake area. As Len pointed out, nothing is gained from oversizing the throttle body, and idle accuracy may suffer.
Data point: Steve Boese (champion of the scientific method in engine development) found that at any sensible rpm for a/c use, the extra two ports in a 6 port Renesis had to be blocked off for best output from the engine. (IIRC, they don't start opening until around 6500 rpm in the car.)
Data point: The fastest (and most efficient) NA 2-rotor I know about is Tracy's RV-4. It's a 'stock' 4 port Renesis with ~11" long *straight* intake runners (whatever would fit in the width of an RV-4 cowl).
Don't forget to use 'velocity stacks' on the input end of your intake tubes; major improvement in flow.
Charlie (Like Len says, 'I may be wrong'...)
This is the set-up i have on my mind at this stage. This is all 45 mm inside diameter intake runners and p port.. Has put the slide throttle for time being out of the picture, due to the fact that it can get stuck to the suction of the ports. The setup is for a side sump the same as that Ed Anderson did on his RV6A.The hot exhaust is much easier to exit in such a setup for me.The throttle body must be at the mouth of the plenum, and if I use a 75 mm diameter it is 30% in mm2 bigger in area than the intake runners area. Don’t know if this is enough to composite for throttle friction by the butterfly and all. Plan to build the plenum so that I can adjust the intake runner length for the optimum rpm. Thanks for all your comments to help me for such a setup as I am still in my childhood, when it comes to rotary`s.
I used the Lucas slide valve system years ago. No problems. It does pool fuel because the injector shoots along the center line and the air flows half way up the opening. I never tried to shake the race car from side to side so I cannot comment on what might have happened. The Lucas system was mechanical with a 95 pound pump. The slide was supported by two rows of tiny rollers. The idea is that there is no butterfly or shaft in the system at wide open throttle. There was a four position plunger to adjust mixture, but only at wide open throttle. Since the injected engine needs no flow depression to function, it is less sensitive to throttle body diameter. Too big and the engine revs stop going up before full throttle. because all of the air required is already being provided, and idle control goes down a bit. With good mixture control, a body not much bigger than the runners would be great. The Pport responds well to ideal runner length but only for a specific RPM. A shorter system with two smaller air filters would work as well and take up less space. Our Pport engine ran a 48 IDA with 44 MM chokes. It would idle down to 600 RPM with ease.
A slide valve is an answer to a question nobody is asking. Just my opinion. I could be completely wrong.
Lynn E. Hanover
In a message dated 6/23/2019 10:55:46 PM Eastern Standard Time, flyrotary@lancaironline.net writes:
I'm actually not sure the correct size. I went with an 80mm thinking I'll be adding a turbo in the next few years. https://www.ebay.com/itm/RED-80MM-THROTTLE-BODY-PERFORMANCE-INTAKE-MANIFOLD-BILLET-ALUMINUM-HIGH-FLOW/322910577197?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 Haven't installed it yet. I've been talking with Neil Unger, who has an 80mm and he said he'd go smaller to 65-70mm. I believe the stock RX8 throttle body is 70mm. So I would guess that if you plan to go turbo, 80mm. If not, stick to 70mm.
- Matt Boiteau On 6/23/2019 4:43:29 PM, Sam Hoskins sam.hoskins@gmail.com <flyrotary@lancaironline.net> wrote: Look up Jenvy throttle bodys in the UK with USA dealers.
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 "cylinder 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 richening 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.? Sent from my iPhone
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