My H4 Project (Long w\ pics)

ianc · 03-26-2005, 01:10 AM

Hi folks,

I just finished my H4 project, so I thought I'd post a little writeup to help the next guy that comes along. At first, I found it to be a very confusing subject!

As an overview, if you have an SC or a Carrera, you're going to have the choice to upgrade to H4's. The SC originally came with the so-called 'sugar scoops'; a cheap American sealed beam in a non-aerodynamic 'scoop'. The American Carrera came with the H5, which has a glass lens in front of the beam, but is still nowhere near the light that the European H4 is. Nutshell.

Back to the project. I had to start with a design philosophy and sketch out a circuit to start. I wanted a professional, overengineered, factory-looking installation. Overengineered, but not to the extent of going the full-blown 4-relay installation.

I decided on two relays, and that I would use the stock Porsche relays as well. Since I had two empty slots in my relay panel, this suited me famously. The circuit I drew is:

All very fine so far. Using the stock relays and panel implies finding some way to wire sockets however. Luckily, I had a donor harness from a junk '77 in the garage:

The socket for the relay is problematic in that the wires are actually cast into the rubber socket. The upper right corner of this picture:

shows the socket after being sliced apart with an Exacto knife, and the wires extracted and desoldered from the relay pin receptacles. The relay is at upper left, and a practice cutup with the method of rejoining the halves at lower right. Lower left shows the small bulb that must be cut off to get a fastening bolt through.

I decided to run 10 Ga wire to the circuit breaker, then tee off into two 12 Ga runs (high and low) from there out to the bulbs. The high and low wires then tee again (for R & L) by using existing blocks at the fuse panel. Just using double-sided tape to mount the CB at present, since I didn't want to drill holes in the tub...

I wanted only one cable run out to the fenders. I was replacing the headlight wires with heavier cable, but wanted to keep the existing grounds, blinker and parking lights. I went to Waytek Wire and ordered plastic sheathing; .5" ID if I recall correctly. This is large enough to take the original cable sheath and the two larger cables I was adding:

so that I ended up with one run. The grommets for the fender and headlight bucket have a small internal ridge that can be sliced off with an Exacto to provide room to pass the larger cable. Cut .5" off the end of it as well. Use lubricant.

Here's the back of a dissected relay socket with the new cables soldered and run in:

Here's the top put on, bolted up, zip tied and fit to the panel:

Another view of the whole panel. High beams on the right and lows at left. Extra turns of new cable at lower left.

ianc · 03-26-2005, 01:19 AM

Finally get the rings back after they've been powder coated and cleared. Place I use in Rohnert Park takes a couple weeks, but the results look worthwhile:

The old:

The new:

Additionally, I thought it would be instructive to take pictures of the light output of the headlights before and after the upgrade. The H4's are using Narva 90/100 bulbs. I photographed this first with the sealed beams, noted the shutter speed and F-stop and set them manually for the 'after' with the H4's. Neither one using flash and all other light sources off.

Before:

After:

Alright, I could have said much more, but that's the general idea and hopefully will give somebody some ideas. Later,

ianc

jeffgrant · 03-26-2005, 04:36 AM

Excellent writeup! I think I was just reading about this in this month's Panorama, if I'm not mistaken.

Now... if only I could figure out how to do that with my slant-nose....

Wil Ferch · 11:41 AM

Nice....

Except you didn't have to cut-up the relay receptacle. I did much the same thing and used a factory receptacle, and put into a "spare" hole opening in the trunk fuse box. Need to warm/soften the receptacle so it 'snaps" into its hole properly. The "pigtails" off the receptacle were soldered/heat shrunk to the remaining wiring elsewhere in the car.....

...so I'm a bit confused why you went to the bother of cutting, etc... ??

Wil

Yellowbird RS · 03-26-2005, 11:19 AM

great work!
well done!

ianc · 03-26-2005, 09:53 PM

Hi Wil,

Quote:

...so I'm a bit confused why you went to the bother of cutting, etc... ??

I did it for the simple reason that I wanted it perfect. I had spent a considerable amount of time running brand new strands of largish headlight wire all the way out to the buckets. I didn't want to use smaller wires to tie into the relay socket. I wanted 10 Ga all the way without breaks, so it was worth it for me...

ianc

CarreraS2 · 03-26-2005, 10:20 PM

Quote:

Originally posted by ianc
The American Carrera came with the H5, which has a glass lens in front of the beam, but is still nowhere near the light that the European H4 is. Nutshell.

Assuming the same wattage high/low beam bulbs are used, is there really a huge difference between the US Carrera H5 (like on an 87-89 car) and a Euro H4, at least as far as the low beams are concerned?

I've had both headlights (on separate cars at separate times) and didn't notice much difference. Of course, that's without immediate back to back use and just relying on memory.

If there is a difference with the low beams, what is it - why does the Euro H4 put out more light than the US H5, assuming both are running 55 watt lows?

SpeedracerIndy · 03-27-2005, 05:49 AM

Quote:

Originally posted by SoCal911SC
If there is a difference with the low beams, what is it - why does the Euro H4 put out more light than the US H5, assuming both are running 55 watt lows?

The light pattern on the H4's is more focused than the H5's. After driving both back to back, I noticed the H5's light pattern seems more scattered than the H4's. Brightness was the same though, at least until I added the 80/100 watt bulbs to my H4's.

Oldporsche · 03-27-2005, 06:30 AM

This is one of those things where physical properties of wattage being the same are overcome with a better product. The original 55 watt sealed beam headlights conform well to 1939 standards. The H4 product is of a superior design and work very well. They too have limitations, however, everyone I know that use the H4's really like them.

David Duffield

CarreraS2 · 03-27-2005, 07:27 AM

Quote:

Originally posted by old_porsche
This is one of those things where physical properties of wattage being the same are overcome with a better product. The original 55 watt sealed beam headlights conform well to 1939 standards. The H4 product is of a superior design and work very well. They too have limitations, however, everyone I know that use the H4's really like them.

David Duffield

I'm not talking about H4 v. original 55 watt sealed beam US headlights (like the ones replaced in this thread).

I'm talking about H4 v. the H5s that are on US 87 and up 911s.

Euro H4:

87+ US H5:

I agree the H4 is a good headlight, and a huge improvement over the US "sugar scoop" sealed beams that came on the early-mid 80s 911s.

But I still submit that the 87 and up H5 is just as good, or very, very close, in actual operation. Close enough that it seems a waste of money to replace the 87+ H5 with H4s. Yes, there is some difference in the lens setups, but the function of the headlights seem pretty close to me. It seems like if the H5 isn't bright enough, it would be a lot easier to just put a higher wattage bulb in it.

Wil Ferch · 03-27-2005, 08:46 AM

It's not so much a matter of brightness,.....but more a case of beam pattern and usability...

It seems to me the H4's are considerably superior to the H5's...once you get over the sharp cut-off characteristics ( top-side) of the low beam H4's...

Wil

SpeedracerIndy · 03-27-2005, 01:41 PM

H4's are also all metal and glass so they won't melt when you put in very high wattage bulbs. I don't know how much plastic is in the H5's, but I do remember a lot of it there the last time I changed the bulb on the 88. I don't know if that's an issue or not with Porsche light fixtures, but I have heard of fixtures melting on other manufacturers when high wattage bulbs are put in them.

Deschodt · 03-28-2005, 07:42 AM

Ian, did you get the car repainted to match the new trim rings ? ;-)

lambertsl · 03-28-2005, 09:09 AM

What is a quick way to tell if mine already has the upgrade. The lens have Halogen embosed in them. This is on a 86.

SpeedracerIndy · 03-28-2005, 09:18 AM

They will say H4 in the center of the lense (at least mine do).

ianc · 03-28-2005, 09:38 AM

Quote:

Ian, did you get the car repainted to match the new trim rings ? ;-)

Ha! I wish Greg... But no...

ianc

Deschodt · 03-28-2005, 09:44 AM

Ian, Remember this ?

Do you still have my SC seats in the car ? ;-)

Anyway, nice job... I spent my w/e installing Sparcos in the 73.5T, houseguests prevented either the recarpeting or the RS door panel installs... Once that is done and the oil sender reinstalled I should be good to go...

KTL · 03-28-2005, 10:41 AM

The H5 bulb housing (with integrated/glued-on lens) is ALL plastic. The aiming cage is the only part that is metal.

Although I do like how the H5 installs and is constructed (besides the plastic issue), when compared to the H4. The H4 setup seems inadequate in the sense that the whole assembly is held into the fender by one screw. If you strip-out that one screw-which is easy to do? You're screwed.

The solution is to weld a proper nut onto the back of the mounting tab, or drill the tab to accept a plastic anchor.

Aside from the mounting issues, I think the lighting of the H4 is much clearer and has a better cutoff. Even with legal wattage bulbs, I thought there was a noticeable improvement with the H4. The spread of light is more consistent and dense. The H5 spread seems to just fade away at the edges.

Nice writeup Ian. Glad I could help. And I thought I went the extra yard with the wiring. You REALLY went the extra mile to wire it the way you wanted to be done. Nice job!

ianc · 03-28-2005, 09:27 PM

Hey Greg,

Yes indeedy I do remember that shot! I seem to recall taking it as a matter of fact! You SC seats are long gone I'm afraid; I replaced 'em with Recaro SE's about 4 years ago and have been really pleased with them. Glad to hear the 73 is coming along fine!

Kevin,

thanks alot for the help; it was your writeup that gave me the most help in actually getting started and I appreciate it!

ianc