Anyone seen the new Speedmaster IR EFI intake for SBF/SBC?

[Ed Wright]

Manifold should work OK, if everything lines up.... MAP signal isn't a downside; using speed density strategy.

Was thinking the vacum holes are too large, too far Down in the runner, but prolly OK?

How about vacum Chamber? Is it Sealed good?

lack of vacuum signal actually is a downside using speed Density, not with Alpha N. Just throttle angle vs RPM with Alpha N.

[surgeline]

Before anybody jumps to conclusions.. and let it be known I have zero interest in ever owning anything from ProCrap/SpeedDisaster .. the Darren Morgan they are referring to races TF in Oz, it's not DM from RM..and they are a bit sponsor on the car.

[panic]

Just a thought on the vacuum plenum?
IMHO those holes to the runners are big enough to affect idle quality. The comparison is between the areas of that hole, and the barely cracked throttle disc.
If you don't need them for an idle signal (but would like normal vacuum function above that), why not insert fittings in each, and tie them to a solenoid valve in the plenum? Run the signal/power lead up through the plenum roof, trigger it by throttle linkage.

[In-Tech]

Manifold should work OK, if everything lines up.... MAP signal isn't a downside; using speed density strategy.

Was thinking the vacum holes are too large, too far Down in the runner, but prolly OK?

How about vacum Chamber? Is it Sealed good?

lack of vacuum signal actually is a downside using speed Density, not with Alpha N. Just throttle angle vs RPM with Alpha N.

Ed, I have never met you but have the utmost respect for you. That being said, I have never seen anything I couldn't do with speed density.

Yes, it is hard when they idle at 87 kpa. Alpha N is A-B(or X-Y whatever floats your boat) and doesn't supply enough resolution for me. You and I both know what happens when Alpha N is used when the "pipe" comes on and that is very temperature dependent and not throttle position dependent. Cover it with fuel and spark in that spot and all is fine.

[ptuomov]

Isn't the normal strategy for load estimation with big cam(s) and individual throttle bodies to use a combination of rpm, throttle position, and manifold air density? At least when street manners are required?

Not to pretend to be an expert, my projects use almost exclusively a hot-wire mass air flow sensor to measure the load. But the way I'd do it would be to dyno tune one set of fuel and ignition maps with with alpha-N (throttle position as load) and second with speed-density (temperature corrected MAP, i.e., density as load) and then blend them and use a weighted average of the two loads. The averaging weight would be mapped from engine speed and density. At low rpms and low density readings, when the manifold vacuum is unstable, the throttle position gets more weight. At high rpms and high density readings, density gets more weight. Or more empirically, give more weight at each cell to whichever method seems to work better. Transitions could be based on smoothed throttle position change only or based on the averaged load (and x-tau or whatnot algorithm the ECU happens to have).

I think (but do not know) that the reason why ITBs help with part-throttle cruise quality is the volume between the intake valve and the throttle being small. With high-overlap cams and big plenum between throttle and intake valve, the process is unstable at low loads (throttle almost closed). If the bang happens to be big, the exhaust creates a strong vacuum pulse at the overlap. If there's a lot of air from which to draw on the intake side, then the next bang is even bigger and the vacuum pulse from the exhaust even larger. Unstable. By placing the throttle close to the intake valve, there isn't much air to draw from, and the range of unstable variation is greatly diminished.

For this reason, just from eyeballing the manifold ports, the vacuum measurement ports look pretty big to me as well. With big cams and almost closed throttles, it's going to draw intake air from those holes and negating some of the benefits of ITB. At low rpms, its also going to push exhaust out thru those holes as well if cams are big, so unless the purpose is a passive multi-cylinder EGR system I'd install restrictors to the fittings. With restrictors, the relatively big vacuum plenum should dampen the pulses nicely and my inexperienced eyes don't see any reason why that manifold wouldn't work pretty well.

Just thinking out loud.

[Cutlassefi]

Thanks for posting the photo. It clairifys WIGO with the connected passage.

The hole in each runner to the vacuum plenum was either 1/4 or 3/16 before I messed with it.

While that might seem like a small hole, in area it is many times larger than the opening through which the ports are drawing the carb signal through the throttle butterflies.

It's not necessarily the small holes vs the cracked butterflies, the dilution comes from the other cylinders. But these plenums are small enough and the fact that they have to draw thru a small hole vs an immediately available large plenum help keep dilution to a minimum. They're not a clean as a true IR but still much better than a typical single 4 barrel intake. Tuned a bunch of IR stuff, Hilborn, Borla, Kinsler etc. Love em.

[Ed Wright]

Manifold should work OK, if everything lines up.... MAP signal isn't a downside; using speed density strategy.

Was thinking the vacum holes are too large, too far Down in the runner, but prolly OK?

How about vacum Chamber? Is it Sealed good?

lack of vacuum signal actually is a downside using speed Density, not with Alpha N. Just throttle angle vs RPM with Alpha N.

Ed, I have never met you but have the utmost respect for you. That being said, I have never seen anything I couldn't do with speed density.

Yes, it is hard when they idle at 87 kpa. Alpha N is A-B(or X-Y whatever floats your boat) and doesn't supply enough resolution for me. You and I both know what happens when Alpha N is used when the "pipe" comes on and that is very temperature dependent and not throttle position dependent. Cover it with fuel and spark in that spot and all is fine.

Sir, thank you for the kind words. I mentioned a *lack of vacuum signal*, not low vacuum. No vacuum signal would cause it to run from the same line or row in the fuel table, or "map" all the time. If a MAP sensor was connected, but no vacuum hose, it would change some with changes in Baro values. The IR stuff I have tuned had no common vacuum chamber. Used Alpha-N. Did a Kinsler converted to EFI recently, and a 409" with one last year. Both show car/street rod vehicles. Used FAST ECUs on both. Using a MAP sensor for Baro reference and an air temp sensor. Both cars drive very well. I tried to get the guy with the 409" plumb a vacuum chamber in on the bottom of the manifold. There was room, but he didn't seem interested. It was an old Algon magnesium set up from the '60s for dragsters. Had Hogan Manifolds in CA build a water & thermostat cross over passage and injector bungs with tabs for the rails. It's in a '62 Bel Air. Show winner, and nice driver.

[machine shop tom]

A customer recently brought in a Professional Products --now Speedmaster-- SBC "Crosswind" manifold, a knock-off of the Edelbrock RPM Airgap.

The Speedmaster piece was unusable out-of-the-box. It was warped .040" on both sides, and the port opening and shapes hinted of a completely new definition of WTF.

An Edelbrock was ordered and compared side-by-side-----the difference in fit and quality was beyond description.

I will never sell a Speedmaster product of any sort.

If I can find the pictures that I took I will post them.

[Cutlassefi]

Not to say what you found isn't true, but I've pulled many Edelbrocks out of the box over the years that weren't much better.

[bmcdaniel]

A customer recently brought in a Professional Products --now Speedmaster-- SBC "Crosswind" manifold, a knock-off of the Edelbrock RPM Airgap.

Speedmaster was Pro Comp, not Professional Products.