vanster

I just bought a pair of Bosch 8" lights. They are DOT lights and I think they are from an '86.
What is the difference between an H5 vs Bosch 8"? I assume the H5 is a Hella light and is Euro?
Currently I have Hella H-4 7" with metal chrome rings and 55/100
watt bulbs. They work great but I like the looks of the 8" lights as for me they seem to be what Porsche had in mind when the designed the car.
Can I replace the stock Bosch bulbs with a high beam similar to the
H4? Are the specific to right and left? Should I have any issues
switching over ( late model 8") to an '80 OB

vanster
'80 5 speed

White Lightnin'

AFAIK, the North American-spec H5 is only made by BOSCH -and it is 8".

The H4 is also available as an 8", also made by BOSCH, but it is referencing the Euro-spec cut of the lens to throw light farther that makes it an H4 (like your 7").

Re-wiring is required to mount Euro-spec lenses/bulbs to a North American-spec car... but it can be done.

SQLGuy

Did US 928's have H4 already in '86? I had an '85, and it did not have them. I had thought they switched in '87, with the S4...

The lamps are specific to left or right-hand drive, but not to left or right on the car.

Pcplod

Do you know what kind of rewiring we are talking about? Is it just changing the plug ends from one kind to another, or are we talking about something more in-depth here?

Thanks for the info!

JHowell37

If the car originally had 7" headlights they'll plug right into a H4 without modifications, whether it's a 7" or an 8" housing. If you're planning to switch to a 8" DOT headlight, you'll have to put on a new plug. They're available at most auto parts stores.

SQLGuy

Apparently, though the physical layout of the plug is pretty much the same, the pinouts are different. There are adapter harnesses out there you can just plug in, or you can cut off the stock connectors and replace with new H4 plugs.

SQLGuy

So the 7" sealed beams used H4 connectors? Cool. Nevermind my previous post, then.

Alan

Sorry - moving from 7" H4's to 8" H5's is functional downgrade - you wil not like the results - I would not do this.

You aready have the 2nd best 928 lighting available and you are proposing to fit the 3rd best. I think the upgrade you want is to the best: 8" H4's - the added advantage is they are plug & play with what you have now.

They are also exactly what Porsche originally intended for the car and what would have been fitted to a German 928...

The beam pattern is clearly superior to the stupid DOT pattern in EVERY respect

Are you are these are really H5's - an '86 would not have had them stock - so they may be upgrades and could be H4's (H5 DOT lights have the 3 protruding nipples on the face while the H4's face is smooth).

Now are you also sure you actually have 7" H4's? - these too are an upgrade from what was stock on your car. If these are sealed beams - they are not H4's (just cheap DOT lights that use H4 plugs...). If you actually have sealed beams now you will be moving up in capability at least a little... but not that much.

Do NOT put brighter bulbs in H5's other drivers will hate you for good reason and may even crash into you...

Alan

Fogey1

The most important aspect of headlight quality, insofar as one wishes to be able to see down the road once the fickle sun has once again absconded with the day, is the design and quality of the lens - much more than the diameter of the lamp and more than the wattage of the bulb.

IMO, the hierarchy of headlights runs:
8" Bosch H-4
7" Cibie H-4
7" Hella H-4

ANY H-5 or DOT lamp is many steps down.

Here's an assortment of informational threads on the subject:
https://rennlist.com/forums/928-foru...eadlights.html
https://rennlist.com/forums/6981990-post14.html
http://www.danielsternlighting.com/

Swapping Euro style 8" H4 headlamps for the US H5 variety on a late model 928
http://www.billsworkshop.com/P928S4/h5toh4/h5toh4.htm

https://rennlist.com/forums/928-foru...eadlights.html

https://rennlist.com/forums/928-foru...ght=headlights

https://rennlist.com/forums/928-foru...eadlights.html

https://rennlist.com/forums/928-foru...eadlights.html

vanster

Let me get this straight. The 8" Bosch DOT ( 3 nipples on the lens) lights that I just bought are less effective that the 7" H-4's that I have currently. The only thing I get out of this is a car with 8" style lights. Am I reading this correctly ?
Is there a brighter replacement bulb like I have in the 7" H-4's?

Imo000

Brigther? Get a pair or new bulbs, check if the power to teh bulbs is strong enough and if that doens't help, get an eye exam.

Alan

Yes - if you have real 7" H4s (bosch/hella/cibie) then you just bought worse lights...

The time to do the research was before... were they new? 8" H4's are typically cheaper than 8" H5's new - can you exchange them?

DO NOT upgrade the bulbs in H5 lenses - it wont help you much and will create trendous glare for other drivers - (ask youself - who exactly are they likely to crash into if you blind them...)

THIS IS AN INSANE THING TO DO!

Alan

SQLGuy

Now you guys are really confusing me.

As I understood it, the 7", pre-S4, US headlights were sealed beams (as required by US law). Sealed beams normally use a 3-pin connector of the same type, but different pinout, than H4.

With the S4, or maybe with the 86.5, since H4's were now legal in the US, Porsche started shipping the 8" H4s. I know for sure that the stock lamps on my '88 are H4 (three bare pins on the lamp) and not H5 (modular plastic plug). I also know for sure that the 7" lamps in my '85 S(3) were sealed beams.

What am I missing here?

Having had both an '85 with the 7" sealed beams, and three other cars with the 8" Bosch H4 lamps, I can say that, for me, the 8" lamps were quite a bit better... they also have that neat little bit of glass that sticks up above the cover at the top so you have secondary confirmation that they're on.


Edit: One of the points where you're confusing me is with the "Any DOT..." statement. All US stock (street legal) headlight assemblies are DOT approved. This includes the Bosch 8" H4's that came on the S4 and GTS. The 7" Hella H4's the OP has are, I believe, not DOT approved and technically "for off-road use only."

James Bailey

The standard 8 inch light as fitted to 87-95 USA 928s is an H-5 and is NOT an H-4. All H-4 lights of all years and sizes are not DOT approved and therefore are illegal in the USA. Porsche designed the 928 to use an 8 inch light and Bosch was and is the ONLY one to make them. Euro spec cars got them, USA cars got fitted with 911 buckets and the 7 inch seal beams as used on a 1957 Chevy..... For the S-4 Porsche created the H-5 as 8 inch lights made by Bosch to look like an H-4 but has aiming **** on the lens and a much different light pattern to get it DOT approved. Also note that the H-4 lights for right hand drive applications are believed to have diffferent cutoff and focus patterns to avoid blinding oncoming traffic.

Jim M.

Re-read what Allen said. H4's were NEVER legal in the USA. The S4 and maybe the 86.5 went to H5's. The H5 is an 8" lamp but it still has the three **** on the front lens. There are dozens of of 928 owners that have converted to H4's because they are far far superior to sealed beams or even H5's. All of the H4's I've seen have "H4" molded into the center of the lens, all of the H5's and the sealed beams have the three ****.