CRX SI convert to HF
 

Is it possible to get the weight of the SI down to the weight of a HF model. Can you just remove a mirror and rear interior parts to make it an HF or is the actual structure of the car lighter? Thanks for any help!

The no power roof helped the weight a lot. So rather then that and the rims there really isn't much you can do. Unless you want to take off the power roof and all the parts associatied with it.

SIs come with a rather hefty weight penalty. And a good deal of it is the result of that power moonroof. Furthermore, if you have a 1989-1991 SI, you also have those stupid door-mounted seatbelts. The reinforcements required to deal with those results in about a 150 pound weight penalty compared to CRXs that have standard pillar mounted seatbelts. These factors, among other things, are the reasons why a 1990-1991 SI weighs 2174 pounds, while a 1988 HF weighs only 1819 pounds. My advice here is to sell your CRX and find an early HF if you want to go this route. But a 1988 HF is not the only possibility. The 1989 HF has no door seatbelts, either. And at 1834 pounds, it is only a little heavier than the 1988 HF. The 1988 DX is another possibility. It weighs 1922 pounds. But because it has no power moonroof, its weight can easily be brought down to HF levels. Of course, a swap will also be required for best economy. But this is your chance to one-up the HF by doing a D15Z1 swap. Also, the 1988 DX is probably going to be MUCH easier to find than the 1988-1989 HF.

I currently don't have a CRX. Three years ago I had a 88 dx and sold it because it was too rusty for a project, Minnesota winters kill body panels. I found a 1990 HF locally but it looks like it has a lot of body work done to it. Does the 1990 model have the door mounted seat belts? I am going to try and find a car from the south with no rust and do the VX swap right away.

Yes, the 1990 model has the door mounted seatbelts.

Yes, it does. The 1990-1991 HF weighs 1967 pounds - a little under 150 pounds more than the 1988 HF. I guess this is not TOO bad. But you are not going to be able to make this car as light as a 1988-1989 HF.

I can't say for sure about the 2nd generation crx, but I know the first generation of them, the HF did not have sway bars, it had a smaller rear axle, simpler plastic body work, lighter weight steel wheels, 1986 crx hf's had aluminum brake drums in the rear, I suspect that the 2nd generation hf has the lighter weight axles just like the base model civic hatch does (26 spline insted of 28 I think), HF crx never had a rear windshild wiper, and was lacking some of the heavier sound deadening as well.

You CAN get the weight of an Si down nearly to that of an HF but it involves the following:

Swap out the deck lid or remove the rear wiper.
Remove the moonroof and plug with fiberglass.

Sway bars weigh a lot more but stiffen the vehicle and give better handling.

Remove stupid seat belts and get the early '88 doors, pillar mount new seat belts - requires welding. Tough to get correct, but about a 150 pound weight savings.
VX or Insight rims & tires.
Removal of anything not necessary in interior helps.
Remove antenna, install satellite radio - helps with FE a little.
If you remove the passenger mirror, get all the appropriate HF markings and bribe someone at the DMV for a new title listing it as an HF as in most states it's illegal to remove passenger mirrors if they came with the vehicle. HF hatch helps with this.

You're better off getting an actual HF - selling an Si if you have it can get you enough money to get the HF, and then just put the sway bars on it.

Also, dont forget to replace the bumper supports with the hf versions. This is a pretty significant weight difference. Also, if you are going to replace the doors, keep in mind that you are giving up some saftey, as one of the reasons the doors are heavier in the later models is the addition of a side impact beam.

You would also need to remove the rear cargo cover and divider, as the hf did not come with these.

I guess it is also possible that the hf seats are lighter than the si, so you might need to replace them to get the weights even (although si seats are a whole lot nicer).

I really appriciate all the help! I will keep looking for a rust free CRX shell or complete car.