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H4 intake and OBD change?


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I read the rules and haven't found anything about this.

I have a 1988 Civic with D15B2.

For H4 classification....


Am I allowed to change the intake manifold from OBD0 DPFI to a more modern OBD1 MPFI and OBD1 distributor.




BTW: I sold the DOHC ZC engine.

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Looking at the rules file https://nasa-assets.s3.amazonaws.com/document/document/4334/HCRulesV19_2017.2.pdf which is in the announcements area, I see that section 5.1 has tables of motor and weight info for H1, H2, and H4, and section 10.0 has info for H4:


10. Allowed Modifications- H4 Only

OEM, stock and/or factory refers to the same model, domestic market and generation as the listed vehicle. When allowed modifications permit other models, domestic markets and/or generations, it will be specified as part of the allowed modification.


I didn't see anything saying that that mod would be allowed...


7. General Modifications- All Classes

7.1 Engine has:

b) Any air intake system in front of the throttle body (including mass air sensor) may be used (stock throttle body must be retained).

c) Carbureted vehicles may use an alternate carburetor of the same design and configuration (for example, a single barrel can be replaced with an alternate single barrel, but not a dual barrel).


so looks like the stock throttle body must be retained...


Section 10.1 has info:


l) Any OEM Honda/Acura chassis classified in H4 is permitted to install a B18A/B engine and transmission swap

a. Minimum weight becomes 2500lbs

b. Permitted to upgrade to Integra front knuckle/hub assemblies

c. Permitted to update to Integra LS/GS 10.3” rotor and brake caliper

d. OEM Acura ECU for the B18A/B engine must be used. OBD0 equipped cars may update distributor and associated wiring to OBD1 or OBD2. This includes the use of a “jumper harness” to convert the OBD0 wiring of the stock ECU plugs to work with the OBD1 or OBD2 ECU. Additionally, OBD2 may also use a jumper harness to convert back to OBD1.


so looks like you could swap in a B18A/B engine and transmission for H4...


I'm not positive what is allowed, so I suggest posting your question on the Nasa HPD Facebook forum at https://www.facebook.com/groups/218610698225711/ as you may get a solid answer, and that forum seems to get more attention. There is also the road racing and time attack forum in Honda-Tech at https://honda-tech.com/forums/road-racing-autocross-time-attack-19/ but it doesn't seem to get as much attention as the facebook forum. - Jim

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Oh..THAT sucks.

What about a Sohc Zc?

Is that engine considered an USDM Si equivalent for H4?


Facebook page has yet to accept my request; 2 months waiting..

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I posted the above info on the Nasa HPD Honda Challenge website, and asked for an administrator to look into approving your request for membership, but if they can't find the request, then I'll just post a reply with any info they post on that forum. - Jim

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Sergio - I went ahead and posted your question in the Nasa HPD Facebook page, and and Marcel De Kerpel and then Sam Myers replied with the info below. I mentioned your name, so hopefully they'll be able to find your request to join that Facebook forum. Anyway, info from Marcel and Sam is below. - Jim


Marcel De Kerpel posted:

He’s reading the rules already, although maybe not understanding them. It’s clear it says if it’s not mentioned is not allowed and for the obd change if you have to use oe computer you would not be able to change dizzy I would think.


and Sam Myers posted:

If it’s an 88 then he can take advantage of the body swap rule and put in a D16A6 and run it at 2150, effectively making it a Civic Si. If he has a D15B2 then the car was a Civic DX, which it came with the same 5-speed gearing as the Si, so he is able to add a final drive and LSD and he’s good to go.


That’s the easy button IMHO...

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