ilko

As part of my winter "maintenance" the car is apart in the garage. So while I'm in there I was thinking of adding an analog boost gauge from the back of my supercharger to the cabin and mounting it where the radio usually goes.

I am not quite clear on how I should route the piping. I was thinking of possibly routing it from the back of the engine through at the top of the gear box, then down the central tunnel. Is that idea feasible? I don't really want to drill any holes in the body unless I have to. I'm also concerned about heat from the engine and gear box melting the rubber piping.

Any other suggestions?

Thanks!

dboyle

I could check the wiring on mine. They mounted mine below where I think the ashtray was/is? Since I bought it supercharged I would have to trace the wire but can do that if needed.

-Dave

ilko

Dave, if it's not too much trouble to check the wiring I would greatly appreciate it!

So yours is an electrical gauge?

Geoffrey

I cannot remember on an RSA if the brake system is hydraulic or vacuum assisted. If vacuum assisted, I'd take it from the front of the car where it attaches to the brake booster.

ilko

Geoffrey, maybe I didn't express myself correctly, I'm looking for a boost reading from the supercharger.

TheOtherEric

Yes, I think Geoffrey perfectly understood, and that's a darned brilliant idea. Wish that would have occurred to me when I installed a boost gauge. I've seen this fat tubing though, and I'm not sure I'd want to try to figure out a way to tap into it.

I ran tubing thru the firewall, behind the rear deck, behing the rear quarter paneling, under the driver's inside door sill plate, and up to the a-pillar. I used a Mazda Miata gauge pod (IIRC) from jc whitney. I can only see the tubing for a few inches to the left of the front hood latch. I got the idea from Basal Skull (993TT forum).

Running thru the tunnel would be worth considering.

Geoffrey

Ilko, the vacuum reservior to the brakes has a large manifold referenced line run to the rear of the car. It will see both vacuum and boost.

Colin 90 C2

Geoffrey that's a fabulous idea.

Eric, how did the install turn out? Any driving impressions or dyno numbers?

ilko

Guys, I think I'm starting to get what you're saying. I'm not that familiar with forced induction, so please bear with me. Geoffrey, thanks for your help!

Should I be looking at tapping into lines 39 and 41 on the diagram below? Or am I completely off base here?

Thanks again!

CWay27

I would get the oversize gauge from auto meter which is over 3" and install it where the clock is. Worst comes to worst, you make a blank plate behind it.

ilko

I already have the location figured out - the radio slot. I'm installing a voltmeter gauge there as well, so it will work well.

ValveFloat

One thing to consider is there is likely a check valve somewhere between the manifold and the brake booster so that the booster maintains vacuum when the manifold is in boost. Depending on where that check valve is will effect whether Geoffrey's idea will work.

TheOtherEric

It was a pretty long process, but I'm at 335 rwhp. Gain was around 140 hp at the flywheel. I posted the dyno plot on the 993 forum. I'm very happy with the car.

That looks right: 39, 40, or 41. It's a big hose, so it may take some creativity to figure out how to adapt that down to a small vacuum hose.

Now I'm curious about that check valve issue.

ilko

Thanks! So if I run a coupler and a hose to the gauge in the cabin I should be good? Or do I need something else? Thanks again!

Geoffrey

The check valve is part 37, so you'd be tapping in before the check valve.