1st Gen Exhaust Question - V8 RX-7 Forum

7got8 · #1 (**permalink**) 11-16-2008, 03:53 PM

I am new to the site and could not find an answer to the following:

Is there a practical way to put dual exhaust on my 1st Gen? I currently have a SBC with exhaust that 'Y's into a single pipe with a cat (coming off soon) and dumps out in the stock location in the rear. I am not at this point willing to modify the gas tank so I am looking for another way to do this. I have climbed underneath and there is not a lot of room from what I can see.

Anyone else already do this?

I have a stroker motor on order with a thumper cam and want to get the most out of the sound bites by adding duals...

Thanks for any help or suggestions...

Jeff · #2 (**permalink**) 11-16-2008, 05:14 PM

you could stand two turbo style mufflers up on their long edge, side by side in the stock muffler location.

stingray-tom · #3 (**permalink**) 11-16-2008, 07:42 PM

Two on one side is the only option, without modifying the tank situation, but i am afraid 2 1/2" well be about the biggest you can do in duals over the rear end. I know one 3" is tight....

7got8 · #4 (**permalink**) 11-17-2008, 10:18 PM

Know of anyone who has removed the tank and moved a fuel cell to the hatch area?

My dad said I ought to see about modifying lakes pipes or use exhaust cut outs...

holtjohn · #5 (**permalink**) 11-17-2008, 11:44 PM

im running a fuel cell in the hatch, and got the exhaust dumped under the car. Im going run it further back when i get the money, its a little loud in the cab.

stingray-tom · #6 (**permalink**) 11-18-2008, 09:42 AM

fuel inside the car is not a good idea, and you won't pass tech inspection at any track that requires it, unless you have a firewall between the tank and the driver... there are plenty of people who make aftermarket tanks in various sizes, with different fill locations in metal and plastic you just have to find one that will work with the clearance and fit your application.... or modify yours by cutting and welding. you will still have issues on that side with the fuel pump and lines, track bar etc. that you will have to contend with.

holtjohn · #7 (**permalink**) 11-18-2008, 10:45 AM

if the tank is vented out of the car I have never had a problem passing tech.

stingray-tom · #8 (**permalink**) 11-18-2008, 12:33 PM

not to try an educate you on the rules, but read the first lines of the first section of the NHRA rule book section 1:5 on fuel systems and tanks.....

Its all basic common sense stuff, first and foremost fuel does not go inside the car period.

Quote:

1:5 FUEL SYSTEMS
Location: All fuel tanks, lines, pumps, valves, etc. must be outside
of the driver’s compartment and within the confines of the frame
and/or steel body. Cool cans, fuel-distribution blocks, etc. must be
located at least 6 inches forward of the flywheel/bellhousing area
on rear-wheel-drive (RWD) cars, and on opposite side of
flywheel/bellhousing area on front-wheel-drive (FWD) cars. Fuelpressure-
gauge isolators, with steel-braided line, may be mounted
on firewall.

Tanks: When permitted by class regulations, fuel tanks located
outside body and/or frame must be enclosed in a steel tube frame
constructed of minimum 1 1/4-inch O.D. x .065-inch chrome moly
or .118-inch mild-steel tubing. All fuel tanks must be isolated from
the driver’s compartment by a firewall, completely sealed to
prevent any fuel from entering the driver’s compartment. All fuel
tanks must have a pressure cap and be vented outside of car
body. A positive-locking screw-on fuel-tank cap is mandatory on all
cars. Insulated fuel tanks prohibited. When used, fuel cells must
have a metal box protecting the part of the fuel cell that is outside
of body lines or trunk floor, excluding hose-connection area in rear.
Non-metallic fuel cells or tanks must be grounded to frame.

Lines: All non-OEM fuel lines (including gauge and/or datarecorder
lines) must be metallic, steel-braided or NHRA-accepted
“woven or woven-pushlock.” A maximum of 12 inches total (front to
rear) of non-metallic or non-steel-braided hose is permitted for
connection purposes only; individual injector-nozzle fuel lines are
excluded. Fuel lines (except steel-braided lines) in the
flywheel/bellhousing area must be enclosed in a 16-inch length of
steel tubing, 1/8-inch-minimum wall thickness, securely mounted
as a protection against fuel-line rupture. Fuel lines may not be
routed in the driveshaft tunnel. NHRA-accepted woven or wovenpushlock
fuel lines: Aeroquip FC300, FC332; Aeroquip Star Lite
200; AQP Socketless; Dayco Imperial Nylo-seal tubing; Earl’s
Prolite; Fragola Performance System Series 8000 Push-Lite Race
Hose; Gates LOL Plus; Goodridge 526; Goodridge 710; Russell
Twist-Loc 836 and XRP HS-79. Contact NHRA for updates.
Pumps/Valves: Cars with non-OEM-type mechanical fuel pumps
must have a quick-action fuel-shutoff valve within easy reach of
driver and be located in the main fuel line between the fuel tank
and the carburetor and/or injectors. Fuel-recirculation systems not
part of normal fuel/pump system prohibited.

Fuel/Air: Any method of artificially cooling or heating fuel
prohibited, except for cool cans. Wet towels, rags, ice, etc. must be
removed before vehicle leaves staging area. Intercoolers may be
cooled with nitrous oxide or freon. Liquid intercooler tanks limited
to maximum 3-gallon capacity, may use water/ice ONLY. If located
in driver compartment, must be securely mounted to frame or
frame structure.
Alternative Fuels: Containers for alternative fuels must be
permanently labeled by the manufacturer as suitable for CNG or
32 GENERAL REGULATIONS
propane. Tank must be vented outside of body. Alternative fuel
systems must incorporate pressure-relief valve meeting standards
listed in NFPA 52. Alternative fuel systems must incorporate a
manual shutoff valve according to standards listed in NFPA 52 for
CNG vehicular systems. All hoses/lines used for alternative fuels
must be permanently and distinctively marked by the manufacturer
as to manufacturer name or trademark, service identifier, and
design pressure. Plastic, cast-iron, galvanized, copper, or
aluminum pipe or hoses prohibited.

holtjohn · #9 (**permalink**) 11-18-2008, 08:40 PM

ya it might be the rules but i have gotten by them I guess. I dont know if it being IRHA is any thing to do with it.

7got8 · #10 (**permalink**) 11-18-2008, 08:48 PM

Here is WA I will not need to take it through emissions since it is older than 25 years and really don't plan on doing any racing--strictly stop light to stop light...

If I cut out the spare tire area to accommodate a fuel cell and vent things appropriately I might get what I want in dual exhaust but it does sound like a lot of work...of course putting my SBC in my RX7 was a lot of work too...

I have a stroker on order--nothing too fancy but an honest 375 hp---will a single 2.5" exhaust really do the trick?

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