Is Deck Lid to Front Condenser A/C Hose a #6 or #8?
 

Doing some hose replacements on my "88 Carrera.

My current car has a No. 6 hose but I think my last 3.2 had No. 8 barrier hose.

I've done some searches and am none the wiser!

Can anyone tell me what size hose this should be please?

BTW: No.6 hose has an external OD of 19mm or 3/4" while No.8 will be 23mm or 29/32"

Thanks!

My 81 original R12 hose is #8. I just pulled it last week.

Thanks Walt!

I've also had a mate send a copy of his Retroair upgrade instructions - remember Rock from Retroair? - showing this hose to be a #6 in the upgrade kit.

So it appears that both #8 and #6 sized hoses get used for this line successfully so I'll leave my current hose as is since it's been upgraded to barrier standard already.

"Factory" condensers other than early modine serpentine
of some VPC systems:

The rear deck lid condenser is a fitting size #8.
The front condenser a size #6.
The factory hose between the two is a #8.

The hose ID's for normal outer diameter and reduced
outer diameter barrier hose are the same.

#8 standard barrier hose outer diameter is approximately .90".
#8 reduced barrier hose outer diameter is approximately .68".

Outer diameters may vary slightly between mfg's, and some
mfg's have made changes in construction to comply with
the "J" spec relative to testing and R1234yf

Thanks Charles.

Do you think there is a measurable performance difference between using using a 8mm ID (ie No.6) and a 10mm ID (ie No.8) hose for this line?

Just trying to figure out if it is worth the cost and effort to return this hose to the standard size.

Thanks!

In auto ac, generally, everything is fractions, though you can play with mm.
#6 is 5/16" ID
#8 is 13/32" ID
#10 is 1/2" ID

When it comes to refrigerant moving through its phases you want a larger
diameter ID when it's a low-pressure gas, such as an evaporator outlet to the suction inlet would be #10.

High-pressure gas, between the compressor outlet and "condensers" is usually #8.

Liquid, after condensers, through the drier and up to the TEV (exp valve), a #6.

When you are running condensers in series the question is when does it become a liquid. For example when we run a rear decklid condenser, 2 rear fender condensers and the front condenser, we run a #6 after the first rear fender condenser. When we delete the rear deck lid condenser and run 2 rear fender condensers and front condenser (or what I'm running now in my 87 cab because I have intercooler; meaning 2 LH rear fender condensers, a condenser in front of the LH front tire and a front condenser) we run a #8 from the compressor outlet to the first rear fender condenser because the design of that condenser is more efficient consistently; it has a fixed fan speed).

On a stock 911, since there is quite a bit of distance between the rear deck lid condenser and the front condenser, about 190" nominal, and the rear decklid condenser's ability to change state from gas to liquid varies with rpm (engine cooling fan speed) along with the variations of ambient air temperature passing through it, you are better leaving it #8 to avoid excessive workload or pressures on the compressor.

Hope that answers your question.

Griff