Originally Posted by kustomizingkid

Holy **** that tubing is spendy... is it really THAT good?

Originally Posted by kustomizingkid

Holy **** that tubing is spendy... is it really THAT good?

Originally Posted by IMZman

I can not find it at the moment, but someone posted a place in Jax, FL that sold VITON tubing at good prices just last month.
<SNIP>
3/16" is the size you need.

Originally Posted by BillM

did a search, seems like the only place to get viton hose is mcmaster (stupid price) and the viton check valves are no longer available. Anyone doing viton?

Originally Posted by CrispyRX7

Bogus.

The vacuum lines aren't exposed to oil in any quanitities that would be overly harmful. You obviously cannot use them for oil lines of fuel lines as the silicone is permeable to those fluids. I just cracked open my car to install a single turbo a few months ago. I replaced all my vacuum lines with silicone back in **1998** - 7 years ago. As of March the silicone was as good as new with ZERO degradation from heat or any exposure to what little oil there might ever have been in the vicinity of the vacuum lines. The 7 year old hose once wiped down of surface dust was indistinguishable from new hose I had just bought.

http://www.negative-camber.org/crispyrx7/gt35rpage3.htm
in the section: SEQUENTIAL TURBO CONTROL LINES AND CONTROL SOLENOIDS
those images are all of my 7 year old vacuum lines. Pliable and as good as new.

A datapoint.

I can also say I've been around FD's since 1996 and never have I heard of anyone in my close circle of friends most of whom have used silicone (those that have not have used viton) with issues of silicone degration due to oil problems for the vacuum lines under the UIM. I will caveat that by stating it's probably not a good idea to use them on the lines to the turbo actuators themselves (there is the potential for quite a bit of oil buildup in that area if you car is particulalry funky or leaky) even though I did and never had to replace a single line.

If you can afford or want to spend the money on viton why not but IMO the silicone is perfectly acceptable. Rubber lines are also fine, they just won't last as long as the silicone or viton.

My input,
Crispy

Originally Posted by DaleClark

Here's the skinny.

The whole silicone deal IMHO dates from WAY back, due to 2 factors. Early silicone vacuum hose typically was relatively thin-wall, didn't fit well, and was more susceptible to damage from oil, fumes, etc. If you get *GOOD QUALITY* hose, from Hose Techniques or High Temp Silicone, your experience will mirror Crispy's - MANY years of trouble-free use. I've used good silicone lines in countless FC's I've worked on with ZERO problems.

Second, the use of Viton IMHO is from someone having problem with older, poor quality SVH lines and looking for an over-engineered solution. IMHO, Viton is a waste of money.

I agree with Jeff - you really don't need to go through and replace ALL the lines. Replace the lines that are routinely disconnected for maintenance (lines to the UIM, for example) and the lines going to/from the check valves and vacuum and pressure chambers. The tons of short rubber lines going to each solenoid will typically stay in place just fine as long as you don't mess with them. You know how everyone complains about how difficult it is to remove those old baked-on vacuum lines? Those suckers aren't going ANYWHERE.

I know Pettit is a fan of using Goodyear rubber vacuum line - that's their deal. I think, again, that it's a case of using poor quality line way back in the day. Also, Pettit tends to go for the simple and "working" solution - SVH is something of a "flashy" mod when you use colored lines. Considering they come from a solid race background, they're more interested in something solid that works, not something colorful and flashy.

I'm also firmly of the opinion that a lot of the vacuum line woes that many FD owners have had were caused my Mazda dealers doing the fuel recall. You have to tear stuff WAY down to do that recall, and I think many of the mechanics didn't get the line routing correct, re-used the stock lines that were vulcanized and popped back off very easily, etc.

Long and short of it - SVH is a really good idea. If you're going for pure reliability, keep a stock of it around to replace old, tired Mazda line when you remove a component from the car. If you have the engine out of the car and you're waiting on parts, might as well do a full job if you feel up to the task. But, if someone came up to me with vacuum line probs, I'd simply replace the lines that needed replacement, replace the check valves, and go from there.

Dale

Originally Posted by Six Rotors

I must say my take on vacuum hoses is a bit different,although it depends on how one uses their car.
The factory hoses on my car lasted 15 years,without problem.So being 65yrs old when I replaced them,I figured that using factory hoses was my best option for the following reasons:
1.They fit perfectly--most are moulded to shape,

2.Under the right conditions they will last 15 years,

3,I will probably be dead or not interested in driving a RX7 before they need replacing.

So what are the conditions which are required for a 15 yr lifespan?Here's my take:

1.Boost levels 1bar or less,

2.Good turbos,ie not leaking much oil into the intake,

3.Good engine seals and workingengine ventilation to minimise pressure in oil pan etc

4.Minimise underhood temperatures---tough but I always open the hood when I stop the car.