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  #21  
Old 05-15-2019, 03:59 PM
86notch 86notch is offline
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Scott I think a real restrictor like that is better then what we are doing now which is using the intake as a restrictor but then having no real way to verify what has been done to them. I donít know either what would happen with varying port volumes while running a restrictor but I would assume it would help even out the field
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  #22  
Old 05-16-2019, 12:13 AM
Ted Johnson Ted Johnson is offline
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Quote:
Originally Posted by Scott Sanda View Post
Perhaps the solution is to put one of these on everything FP. Sized to allow a specific flow.

Then the port volumes, and all the other stuff theoretically do not matter.

Is that a valid theory?

If you kept the cam specs, carb specs and displacement specs, would a cheated up intake or head even show a difference if the restrictors were really sized for say 425 HP at peak flow?

I am posting this as food for thought. There would obviously need to be adjustments to the RP cars as well.

https://www.summitracing.com/parts/aaf-all26060

https://www.summitracing.com/parts/aaf-all26066

Scott. Here's a link to a long discussion on this forum regarding sonic air restrictors , plate restrictors to rev limiters. Beating a dead horse on any type of restrictors to this audience. Let it go. Not worth the effort
http://www.asedan.net/forums/showthread.php?t=2734
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  #23  
Old 05-16-2019, 06:57 AM
jimwheeler jimwheeler is offline
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That discussion was started about 8 years ago, before the RP cars, except for the GTO. Not sure the discussion would go the same way today.
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  #24  
Old 05-16-2019, 10:24 AM
Scott Sanda Scott Sanda is offline
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Jim,

That is why I threw it back out there.

Plus, this is an easy to tech restrictor.

It would need to be a phase in, for sure. Weight breaks for anyone running it, etc.

The community would need to have a targeted HP based on the airflow.

Scott
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  #25  
Old 05-16-2019, 11:00 AM
MarkMuddiman MarkMuddiman is offline
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We already have a restricter for FP cars - the 600 cfm Holley
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  #26  
Old 05-16-2019, 11:30 AM
jimwheeler jimwheeler is offline
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Mark,
That was the key to the argument back then, and why some people were bounced at the RA Runoffs for modifications to the Holly. The h.p. of the FP cars has stabilized, and is pretty even from Ford to GM, but not necessarily from one engine builder to the next.
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  #27  
Old 05-16-2019, 11:36 AM
Ted Johnson Ted Johnson is offline
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Quote:
Originally Posted by Scott Sanda View Post
Jim,

That is why I threw it back out there.

Plus, this is an easy to tech restrictor.

It would need to be a phase in, for sure. Weight breaks for anyone running it, etc.

The community would need to have a targeted HP based on the airflow.

Scott
You have good intentions and so did former asac member Kyle Watkins with researching sir restrictors. A shame he was bounced off the committee. Wanted to accomplish the same idea. Copied from 8 years ago. Kyle speaking.

I want to stress I am just brainstorming here. I don't know enough to be for or against this, or even if it is a viable suggestion to consider. But, if reliability problems are cropping up from too much HP and RPM, and participation problems are cropping up from too much HP and RPM, and new AS efforts are discouraged by too much HP and RPM, and Limited Prep Crossovers are discouraged by too much HP and RPM, then I thought about the restictor and rev limiter as a multi facet possible solution.

My experience with them is limited to helping others in my region with a few of their race cars.

Walther, the issues you bring up and many others in fact, have been tackled by the classes that have used them for awhile, so one merit of this idea is it is not re-inventing the wheel for the purposes of a club racing application.

Dean - I don't think our current carbs are the limit at all, as the rumors of 8600 rpm and high 4 to low 5 hp numbers are out there with the current carb. In fact, a 390 carb still can deliver 600+ hp in a nascar application, so we aren't using all of our carb.

It was believed by many the edelbrock flow numbers would be the limit.

In fact, I would hope that the restrictor would not slow down the average of the top 5 lets say.

Many have invested in a nice piece that would race reliably at 7000-7500. I would advocate a RPM limit in that range. Further, I would advocate a restrictor that is invisible to say Wheel's motor or Chuck's. The first step up from the iron heads has not been a problem, its just seems that the newest horizons are.

Anyway, to answer Walther - In the other classes the SIR feeds and airbox, and the carbs (and their float boal vents/emulsion tubes) are exposed to or even completely housed in the airbox. I believe that the tech procedure as it drives into impound is to hold the car at 2000 rpm and put a rubber ball in the SIR as a plug and the car has to die within 20 seconds. The airbox and tubing has to hold up to that, so that seems like a solid idea.

There may be complex ways to cheat that, but that is true with any of our rules.

All of our cars have the same holley carb and the same 14x3 aircleaner that fits under the hood and has the holley air bleeds and bowl vents seeing filtered air. So, I think it would be a natural to spec the airbox as that 14x3 round housing, with hard sides and a "snorkel" heading for a headlight, with the SIR at or near the headlight. Put a smaller around filter like a 12", in the air box behind the strip of aluminum making the filter housing hard sided.

Developing a true airbox like these side draft GT cars for example is an added complexity and expense that I don't think we need to mess with, so I would suggest a simple spec airbox.

To me, there is one critical key about this idea would have to prove true with a bank of good evidence. That is, that the SIR is really an absolute limit (Vs. a relative limit), and it is invisible to the motor until that limit is reached. This is key.

Another key is that we don't change the engine build to allow messing around with high compression or low compression with porting etc etc etc... Just make this is nearly as simple as an electronic rev limit.

If an SIR doesn't really work this way, then I wouldn't be for it.

Anyway, curious about the discussion on it.

Kyle
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  #28  
Old 05-16-2019, 12:47 PM
Ted Johnson Ted Johnson is offline
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https://www.raetech.com/Restrictors/...estrictors.php
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  #29  
Old 05-16-2019, 01:05 PM
Ted Johnson Ted Johnson is offline
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Single Inlet Restrictor Function
Internal combustion engines combine fuel and air to produce horsepower. In the case of a gasoline engine, airflow is always the limiting factor. A single inlet restrictor predictably and controllably limits airflow and thereby power. Sanctioning bodies are increasingly mandating single inlet restrictors in an effort to predictably and controllably limit power. Raetech has developed a line of restrictors that have been optimized through computational fluid dynamics and designed to thrive in the harshest environments making them the most thoroughly engineered restrictors available for purchase.

Choke flow is the distinct limit when the restrictor will flow no more air, regardless of downstream vacuum. This occurs when the flow velocity reaches the speed of sound across the restricted area. The Raetech restrictor is designed to provide minimal effect up to choke flow and to achieve choke flow at the lowest possible pressure drop. Minimized pressure drop to achieve choke flow means an engine with a Raetech restrictor will have to work the least to achieve the power limits imposed by running a restrictor. Lesser restrictors will require running the motor in a higher rpm band to create enough draw to achieve the rules-limited amount of airflow. This increased rpm adds power-robbing friction along with wear and tear. Besides making more power, the best restrictor you can buy should save you money in the long run due to better engine life and longer intervals between rebuilds. The results of a restrictor on a simulated flow bench are shown below.
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  #30  
Old 05-16-2019, 03:45 PM
jimwheeler jimwheeler is offline
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Good conversations, but, FYI, Kyle was not "bounced" from the ASAC.
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