question about engine swap

[bamajason]

ok i have a 1990 240sx with the ka24e motor in it. and i was wondering if i swapped in a motor from the later 240sx with the ka24de motor would that put me in another class like SM?

[engled]

There is an update/backdate rule that starts in SP. If the car such as a 1991 240sx is on the same line in the rulebook (which it is) as 1995 you can use either engine as long as you swap the transmission as well. This would put you in DSP.

[bamajason]

ok thanks!
the tranny in the sohc and dohc is the same. so it looks like i might end up running in the dsp class. i will have to look into that class some more to see what mods i can do and can't do. not sure if i will be making this next event running. the motor in the budget 240sx project just don't want to help out. its making some nice sounds from the top end.

[engled]

SP is all the same as stock plus tons...

Any spring/shock/sway
Intake and exhaust is pretty much unlimited.
Any diff
The update/backdate rule can save you a lot of weight some times
Any seat
Lap belt only if you should so choose
You can remove radio/speakers/AC
I think brake rotors are open now (double check this)
and a bunch I'm leaving out.

[TouringBubble]

Last I read in '09 you had to keep the same style and size rotor (i.e. no 2-piece), but you could do slotted or drilled or whatever. May have changed though.

[kilgojr]

C. Equipment and/or specifi cations may be exchanged between different
years and models of a vehicle if (a) the item is standard on the
year/model from which it was taken, and (b) the years/ models are
listed on the same line of Appendix A (Street Prepared Classes). The
updated/backdated part or the part to which it is to be attached may
not be altered, modifi ed, machined or otherwise changed to facilitate
the updating/backdating allowance. Standard factory installation
methods, locations, and confi gurations are allowed. The updating
and/or backdating of engines, transmissions, transaxles, and/or unibodies
must be done as a unit; component parts of these units may
not be interchanged. Cars not listed in the Street Prepared sections
of Appendix A may not be updated/backdated until approved by the
SEB and published in the offi cial SCCA publication.

[kilgojr]

I know you had a question earlier about wheels. If you are going to run in DSP here are the rules for that.

15.4 WHEELS
Vehicles may only exceed the allowances of 13.4 as specifi ed herein.
A. Wheels of any diameter, width, or offset may be used. Aftermarket
wheels may be modifi ed to install OE tire pressure sensors.
B. Wheel spacers are permitted. Wheel studs and knock-off wheel drive
pegs may be changed in length and diameter. Wheel bolts may be
replaced with studs and nuts.

[kilgojr]

Brakes 15.6

D. Alternate brake rotors are permitted, subject to the following restrictions:
1. Rotors must be ferrous metal except for standard parts. Aluminum
rotor hats are allowed. Rotor dimensions (diameter and thickness)
must be equal to or greater than standard parts. Cars originally
equipped with solid (non-vented) rotors may utilize vented rotors.
2. Cross-drilled and/or slotted brake rotors may be used. Slots/holes
are permitted only in the braking area of the rotor. Rotors featuring
a drum-type parking brake in the hat area of the rotor may not be
drilled or slotted in the parking brake area.
G. A functional, redundant emergency (parking) brake must be present.
H. Brake calipers may be replaced, provided the number of pistons
is equal to or greater than the original number of pistons. Caliper
mounting brackets may be replaced to accommodate this change,
but may serve no other purpose. Alternate caliper brackets must bolt
to the original caliper bracket mounting location(s).

[AlanB]

As good a time/place as any for this debate.

I (still) think the update/backdate rule does not require engine and trans be swapped as a 'unit'. Component parts of a single unit may not be swapped around, i.e: specific trans gears swapped into otherwise legal transmissions, specific heads swapped to different blocks, or a specific ring and pinion setup in an otherwise appropriate housing...... cams, lifters, etc. The key is in the SCCA definition of the word 'unit' but I can't find any logic or lanuguage that supports that the engine and trans are considered single unit.

There have been loads and loads of cars that have 'legally' run transmissions different than what came with the engine itself- There is certainly precedence (seriously ancient precedence) for motor installs without the matching trans, and vice versa. As long as you don't have to cut anything/drill anything or otherwise fab anything up to make it work, AND it's listed on the same 'line' in the book, AND you bring any/all required associated parts off the same line it should be good to go. In most cases, the business of being on the same line will take care of this and only provide update/backdate selections that are 'bolt on'.

As an example, a 1st gen RX7 ('79-'85) can swap to any of the 13B engines listed on the same 'line' in the book. However, the 13B engine is 3/4" longer than the 12A. If you want a 13B to be a legal SP install, you cannot redrill the motor mounts on the subframe 3/4" forward, you must find and install the subframe from an SE car which came with the 13B and has the mounts in the correct location OR purchase a legal aftermarket engine mount that can accomplish the same task. It's been too long ago and I can't really recall, but I seem to remember the Racing Beat mount for this job was NOT legal. Specifically in SP, motor mounts are upgradeable but there are conditions. Getting a legal aftermarket part is sometimes tough if not impossible and is often debatable in protest.

I'd like to hear Charles's and Clay's opinons on the 'engine/trans as a unit' thing.

[kilgojr]

Jason,

in your case this rule is not going to affect you since the tranny is the same for both motors. What you do have to be careful about is what Alan is saying about the motor mounts, and trans mounts. Running in DSP, the motor and trans mounts can be replaced with a harder material (poly, delrin, etc) but has to have the same amount of material as the stock mounts. For example, I run SM, my motor/trans mounts are solid aluminum. These are not legal for DSP, which is what I would be classed as if my car was SP. The reason is that the original rubber mount had a metal disc on top and bottom with rubber in the middle. So if I upgraded I would have to have a mount that had a metal disc on the top and bottom and then delrin, poly, etc in between.

[Cholewa]

If you're not planning on taking it to a national event, and you aren't the god of racing, it really doesn't matter what class you run. Until you start beating people, you won't get contested at local events.

[kilgojr]

If you're not planning on taking it to a national event, and you aren't the god of racing, it really doesn't matter what class you run. Until you start beating people, you won't get contested at local events.

correct.

Although I do plan to be looking thoroughly through Matt's car this weekend.

[Cholewa]

I think I'll run the rabbit in SM... It does have some new sticky wide tires on it.. almost as wide as yours..

[kilgojr]

bring your volvo!!!!!!!!!!!!!!!!!!!!!!!!!

[JohnW8]

As good a time/place as any for this debate.

I (still) think the update/backdate rule does not require engine and trans be swapped as a 'unit'. Component parts of a single unit may not be swapped around, i.e: specific trans gears swapped into otherwise legal transmissions, specific heads swapped to different blocks, or a specific ring and pinion setup in an otherwise appropriate housing...... cams, lifters, etc. The key is in the SCCA definition of the word 'unit' but I can't find any logic or lanuguage that supports that the engine and trans are considered single unit.

There have been loads and loads of cars that have 'legally' run transmissions different than what came with the engine itself- There is certainly precedence (seriously ancient precedence) for motor installs without the matching trans, and vice versa. As long as you don't have to cut anything/drill anything or otherwise fab anything up to make it work, AND it's listed on the same 'line' in the book, AND you bring any/all required associated parts off the same line it should be good to go. In most cases, the business of being on the same line will take care of this and only provide update/backdate selections that are 'bolt on'.

As an example, a 1st gen RX7 ('79-'85) can swap to any of the 13B engines listed on the same 'line' in the book. However, the 13B engine is 3/4" longer than the 12A. If you want a 13B to be a legal SP install, you cannot redrill the motor mounts on the subframe 3/4" forward, you must find and install the subframe from an SE car which came with the 13B and has the mounts in the correct location OR purchase a legal aftermarket engine mount that can accomplish the same task. It's been too long ago and I can't really recall, but I seem to remember the Racing Beat mount for this job was NOT legal. Specifically in SP, motor mounts are upgradeable but there are conditions. Getting a legal aftermarket part is sometimes tough if not impossible and is often debatable in protest.

I'd like to hear Charles's and Clay's opinons on the 'engine/trans as a unit' thing.

In the case of the Miata, if you purchase a new trans from the dealer it will be a 1999 model, since they no longer make the early (NA 1.6) transmission.