Manifold / TB rule revisions

[Z3_GoCar]

The "writing a rule to prevent something specific" trap. I believe that's Ad Hoc committee standard error 37.1...?



K

Aye-yup.

What makes the rule ambigous is somehow the words "for the installed engine" got left off of the TB limitation.

Therefore, the BMW in question would not have the option (assuming 6cyl) of using the ITBs from an engine that is not allowed in STU, even though it came in his chassis at some point in time.

I will submit a letter to get this clarified

Good call, D.

Greg, you really flip-flopped on that one....

Actually, even if you add that it still presents a problem. What if you're starting out with a car from a smaller displacement and going larger. Then you're limiting the car to what came with it on the smaller displacement class. Just take Kirk's advice and scrap this rules abomination.

 

[Chip42]

isn't it supposed to be about displacement?

if you don't want a specific list of OEM intakes, list the forbidden OEM intakes.

you already forbid specific chassis and whole engines, this doesn't seem a stretch of the current rule style, and keeps wonky unusable and unintended consequence ridden rules out of the book.

 

[dhrmx5]

It's under the section just added last month 9.1.4.G.1.e.1:

1. Regardless of the intake chosen, the total number of throttle bodies must remain the same.

The same as.... the chassis, the motor, or??? My chassis has two different generation motors installed in it along with about seven different motors, one of those has a two barrel throttle body, five have a single barrel (some are cable operated and some are electro-servo,) and one has six throttle bodies. All of these motors are in my dealer sourced shop manual, and are USDM.

Any insight into what this means? Thanks Greg.

James[/QUOTE

This rule was specificaly written to ALLOW the use of either the intake and TB from the installed engine OR the intake and TB from the chassis. This was to facilitate the install of RWD/FWD engines in either RWD or FWD chassis.(example: B18 GSR engine in S2000 for STL) The manifolds frequently prevent the install because most FWD manifolds would point at the firewall.

With this rule you could install a 2.3L MZR engine in a 06+ MX5 and build a competetive car for STU. Conversly, it would allow the install of a 2.0L MZR into a Mazda3s for STL.

To prevent the use of the BMW ITB setup that came in some of the 3 series, Z4s, etc from being used with the approved engines in STL and STU we made the rule reflect that the number of TBs had to remain the same as the INSTALLED engine came with.

So far that is the only conflict we can think of that needed resolving.

The rule was made confusing because the words "for the installed engine" got left off. We don't care if the TB has one or twenty venturis, as long as it is stock and unmodified.