jthwan22

What is under stock fuel rail cover? Should I use home Depot pipe insulation or stock covers?

jon928se

On your 88 - by now crumbled away foam.

pipe insulation seems to work well - the softer closed cell foam stuff not the "plastic" foam. Sorry my description isn't very good. I could say the ins you get in australia not the ins you get in the UK but that doesn't help you a lot.

Apparently you can glue the slit in the foam back together with super glue - cable ties seem to displace themselves after a while.

Alternatively super glue the foam to the inside of the rail ocovers - essentially what the 90 onwards 928s have.

anpo

Roger have new ones, GTS style. They're not even expensive..

aaddpp

Is there any harm in going without the insulation material? Like others mine was dry and of no use...I just vacuumed it out.

Vlocity

I don't think that there is any harm. One opinion was that the insulation was there to quiet the injector noise. But if Roger has a replacement I would put them back to stock while you have them apart.

Ken

AO

I wouldn't bother, personally.

ROG100

The insulated GTS style covers are the only ones available now and not so bad at $42.79 each.

SteveG

I wouldn't swear to this, but I think it is about fuel temp not injectors; fuel flow is fairly slow except on Andrew's supercharged beast and the cooler the better. It sounds like something I'd replace if it was only $84 every 15 years. I'm guessing it's not critical for street use and a Home Depot substitute would be acceptable. OTH, I wonder what will be the cost 2025?

jon928se

The stock (90 on) insulation only covers the top of the rails. Given that most of the heat comes from the engine not the hood I'ld surmise that the insulation is for sound not heat. FWIW I've been running my SE for years without the insulation. Only perceptible difference is that you can hear injectors firing.

Hilton

The specific product Jon means is known as "Armaflex Tube" in the US.

Its a very flexible closed-cell pipe insulation.

For refurbishing S4 fuel rail insulation, I use the 3/4" ID, 3/8" wall thickness tube (stamped 20 x 9 - for metric sizing) - slit it down one side, make cutouts for the legs and injector holes, and then use regular "Super glue" (cyanoacrilate) to re-seal the slit (it welds the closed-cell foam, not just sticks it).

Looks great, and being closed-cell will resist moisture, oil, fuel etc. much better than the original foam.

I considered downgrading to the GTS-style covers, but decided I'd rather have the all-round insulation for noise-reduction purposes, and to reduce heat-soak in our hot climate.

SQLGuy

It shouldn't be that slow, as these cars all (or, at least, all non-CIS) used a return-to-tank setup, so "excess" fuel bleeds past the regulator and goes back to the tank. The heat exchanger with the A/C lines helps cool the fuel when the A/C's running to help cool injectors and prevent vapor lock. Not sure whether CIS uses a return-to-tank setup or not.

As such, the insulation may be for keeping the fuel cool and keep it from circulating too much engine heat back to the tank.

IIRC, though, the pre-S4 cars didn't have insulation on the fuel rails... at least my '85 didn't.