Mar 2nd, 2014 - JDM Front End Info - What to know when doing a JDM Front End Swap on a CRX / CR-X.

JDM FRONT END INFO:

Background:

With the mid-generation update for the Japanese EF CR-X in 1989 (for 1990 model year), Honda  released a new model (EF8 SiR) as well as a new look for the front of the vehicle. This new front end is colloquially known as the ‘SiR Front End’. Contrary to popular belief, this was used on all three chassis: EF6, EF7, and EF8.

This front end used the same fenders as what was used in the previous two model years (using thinner moldings, however); a different mounting for the corner markers (no visible mounting hardware); longer headlights; a hood with a raised middle section (as opposed to the raised bump used on the 1988/89 EF7 ZC-equipped CR-X); and a different look for the front bumper too: wrap-around style signal lights; thinner moldings and updated grill design as well as ‘ducts’ on the sides of the bumper.

1988/1989 Style:

1990/1991 Style:

The special editions of the EF6 (1.5x Style SII, and 1.5x Limited Edition II) had a variant on this front end as well. The bottom textured surface was painted a gold or silver color (I can’t really tell from the pictures or the brochures).

The S2 used a painted front lip and the LEII did not.

Style SII:

Limited Edition II:

Terminology:

First lets start off with a ‘body lesson’… we will be using these terms frequently in the following technical information.

This is a front bulkhead:

This is the Rad Support:

This is the Hood Latch Receptacle:

 

Technical:

With the introduction of the EF8 chassis SiR, Honda also introduced the new B16A engine. This larger engine required a slightly larger engine bay (hence the problem most of us have when we do a swap – barely enough clearance). To solve this problem, Honda extended the body approximately ¼ of an inch.

This can be illustrated by measuring the gap between the headlight and the front bulkhead on this nose-cut EF8:

This extension was not necessary on the EF6 or EF7 chassis as they both used a smaller motor than the EF8. The size of the EF6 & EF7 engine bay remained unchanged from 1988 on, but for ease of production, Honda incorporated the exact same hood and bumper on the EF7 and EF6 as they did on the EF8.

Since this front end was developed for the larger engine bay requirements of the EF8, the hood would not latch properly on the other two chassis because of the smaller engine bays of the EF6 and EF7.

To correct this Honda engineers came out with a new Rad Support which moved the latch receptacle forward ¼“. 

1990-1991 EF6/EF7 Rad Support:

 

Why is this important? Because North American CRX are based on the EF6 / EF7 chassis design from 1988... (the one with the smaller engine bay). This is why when using a genuine EF8 rad support for your ‘SiR Front End’ conversion, the hood will not close properly. We have a smaller engine bay, just like the EF6 & EF7s. We have the same problem with hood closure that Honda engineers had when they tried to put the ‘SiR Hood’ on the EF6 & EF7 chassis back in 1989.  

This can be illustrated by placing the same headlight on the North American chassis and measuring the headlight gap (I have personally witnessed the same gap on an EF7 nose cut, but I could not obtain photographic evidence for this article):

“But I was told that all I needed was an SiR Rad Support?”  Wrong. This is a ‘JDM Urban Legend’. All you really needed was an EF6 / EF7 Rad Support.

This same solution that the engineers at Honda devised for their fitment problems will help you too. It will compensate for the smaller engine bay and it is the only Rad Support that does not require any modification to allow the ‘SiR Hood’ to latch properly on the North American chassis.

Note: Both the North American and EF8 Rad Supports can be used however modifications must be made in order to have the hood latch properly. 

The following picture illustrates the differences in Rad Supports between EF7 (illustrated in black), EF8 SiR (illustrated in grey) and North American (illustrated in red):

 

The EF8 Rad Support (gray) is easy to spot because of the large rectangular hole cut in it for the ducting of the factory air intake system. The latch receptacle is positioned almost identically to the North American rad support (red).

The EF7 Rad Support (black) is easily identified by is more angled appearance, and also by how much wider it is than the either the EF8 (gray) or the North American Rad Support (red). It is also lacking the large opening for the intake ductwork. Also note how the latch receptacle is moved forward ¼” further than the North American or EF8 Rad Supports.

To summarize:

-          EF6, EF7, & EF8 Chassis all used the ‘SiR Front End’ in 1990 & 1991.

-          EF6 & EF7 Chassis’ engine bays were smaller than EF8’s.

-          EF8’s engine bay was ¼” longer which is why the placement of the latch receptacle on the rad support is further back.

-          EF6 & EF7’s latch receptacle is placed ¼” forward to compensate.

-          EF6 & EF7 Rad Supports are the only ones that allow the ‘SiR Hood’ to latch without modification when used on North American CRXs.

-          EF8 & North American Rad Supports can be used on the ‘SiR Hood’ but will require modification to allow the hood to latch properly when used on North American CRXs.

-          EF8 & North American Rad Supports can be interchanged on the North American front ends on North American CRXs without modification.

-          EF8 Rad Support has hole for ducting for air intake system.

-          EF7 Rad Support has a more ‘angled’ appearance, and is wider than EF8 & North American Rad Supports.

Remember, this blog was written in chronological order so, you will need to click OLDER POSTS to move forward in time, and click NEWER POSTS to go backwards.