Non-stock induction (SP only) - clarification

Discussion related to classification of cars in the NEHA series.

Non-stock induction (SP only) - clarification

Postby drummingpariah » Mon Feb 10, 2014 9:40 pm

I've been through the rules a few times, but I've had a tough time determining exactly what's meant by 'non-stock induction' for SP. It's clearly spelled out in Unprepared, but I'm trying to figure out what my classification is going to be for this season and that 10% is the difference between going to the top of the hill as an s4 ... and going to the top of the hill as an s2.

This is obviously a huge distinction for me, because I'll be much more competitive during my first season if I'm in a lower class.
[/sarcasm]

While it really doesn't matter at all, I'd like clarification just for peace of mind. If possible, I'd like to be in a class populated with cars that are putting down realistic target times for me to compare to (read: s4). I have an l28et engine in a 280z chassis, which was never a combination that came from the factory. The primary difference between the l28e and l28et is that little t on the end, indicating forced induction. All the mechanical components on the engine are stock to that engine. So, for swapping an n/a EFI engine out for a turbocharged EFI engine cost increase my adjusted displacement by 30% or 40% at the end of the day?

In the 'unprepared' section of the classifications document, it states that:
Other than the air filter and its housings the induction system may not be modified to allow more air into the engine, such as oversize throttle bodies, carbs, or intake manifolds.


I'm unclear as to whether that also applies to SP, or if the l28et intake manifold is considered a modification. If it is, would swapping the original intake manifold back on negate the 10% from non-stock induction, or does the turbocharger automatically force me to accept both?

https://www.dropbox.com/s/gya2d1n8qdkpjvt/280z%20-%20L28ET%20-%20Hillclimb%20Classing%20Sheet.xls - Here is my current calculation xls (currently sp4), please feel free to let me know if I'm off on anything.
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Re: Non-stock induction (SP only) - clarification

Postby walterclark » Tue Feb 11, 2014 10:04 am

I am not exactly sure what the correct answer is, but my gut says the I28et intake and throttle body on a I28e does not fall into "modified intake".

Per the rules... The allowance for updating and backdating is within "the model". But that is where it gets tricky. Define the model as 280Z (S30 chassis) where the I28et engine is from a different model - by Nissan's labeling, the 280ZX (S130 chassis) - and its not free. If one includes all the first and second generation (240Z thru 280ZX) as a single family then you are absolutely fine without taking the 10% hit (assuming we are not including the turbo in the 280Z).

I would be inclined in this case to do the latter because of the similarities between the S30 and the S130 chassis.

Other classification committee members may see it differently and I would like them to weight in.

PS. We have had similar discussion in the past. For instance where is the limit regarding allowed updates within the VW Golf model? They have used the Golf moniker across 6 generations of chassis (7 in Europe) spanning 40 years.
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Re: Non-stock induction (SP only) - clarification

Postby drummingpariah » Tue Feb 11, 2014 10:23 am

walterclark wrote:I am not exactly sure what the correct answer is, but my gut says the I28et intake and throttle body on a I28e does not fall into "modified intake".

Per the rules... The allowance for updating and backdating is within "the model". But that is where it gets tricky. Define the model as 280Z (S30 chassis) where the I28et engine is from a different model - by Nissan's labeling, the 280ZX (S130 chassis) - and its not free. If one includes all the first and second generation (240Z thru 280ZX) as a single family then you are absolutely fine without taking the 10% hit (assuming we are not including the turbo in the 280Z).

I would be inclined in this case to do the latter because of the similarities between the S30 and the S130 chassis.

Other classification committee members may see it differently and I would like them to weight in.

PS. We have had similar discussion in the past. For instance where is the limit regarding allowed updates within the VW Golf model? They have used the Golf moniker across 6 generations of chassis (7 in Europe) spanning 40 years.


That makes perfect sense. The problem is that looking at it from both perspectives makes perfect sense. I'm sure it's a discussion that comes up often with many models. I'm hoping that because both engines (the l28et and l28e) are in the same family, that would overrule the model name difference, but that's a judgement call for someone with more experience than I have. I'm not sure there's a 'correct' answer, but I think we can get close by coming up with a 'consistent' answer: As long as it's handled consistently with previous situations, and future situations are handled similarly, I think that's the best we're going to get.

Also, I want to clarify what I'm saying to avoid any confusion:
Currently, a complete l28et engine (stock low-compression f54 block, stock p90 head, stock intake and turbo manifolds, etc) sits in the engine bay. I have two complete n/a engines (n42 block/head combinations) with n42 intake manifolds. Those are stock to the car. If the intake manifold is the issue, that's an easy (weekend) swap from the p90 manifold to the n42 manifold. There would be no noticeable performance change in either direction; That change would be strictly to adhere to the classification rules.
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Re: Non-stock induction (SP only) - clarification

Postby Mopar 151w2 » Tue Feb 11, 2014 1:27 pm

Generally speakin' we take the car for what you say it is at registration, and that holds unless you get protested. At least in theory, it is primarily the entrant's responsibility to class the car - if registration classes the car, all they did was help the entrant (And no blind squirell comments from the peanut gallery!)
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