speedtigger

iTrader: (16)

I want to discuss using stand alone fuel systems for the fuel side of your nitrous system. Specifically running race gas in the stand alone with pump gas in the main tank feeding the engine.

Some have told me this will work great, others say don't mix fuels because of the different burn rates.

Discuss......

Doug G

Higher octane fuel = slower burn rate (resistance to detonation).
I know a lot of that do it this way....
As I understand mixing say 91 and 110 50/50 doesn't equal 100, but does raise the octane some (to what extent I'm unsure).

I would think it comes down to how much juice you're shooting if you run a dedicated system ?

speedtigger

iTrader: (16)

I wonder how much difference it could make. For example our carbed cars have the equivelent on 4 .084" jets flowing at WOT, while the nitrous jet is just a single .050" to .090" jet on your average plate system.

ZONES89RS

iTrader: (25)

I prefer a dedicated system. There is no guesstimating and hoping you put enough good stuff in the tank, it is pure when sprayed in. No if or but. 93 in the tank. I am budget oriented so the airport on the backside of my house takes care of my fuel needs. Av gas gets it done for a few bucks a gallon.

Doug G

Nitrous is an Oxidizer and needs the added fuel to burn or else it will start eating parts.
The Carb can't adjust in that way for the sudden burst of oxygen in the same way an injected motor can with the O² sensor....and as before, only to a certain extent.

Once you get over 150-175 shot, the cylinder pressures get very high which could lead to the 91/93 octane fuels inability to resist ignition which then requires the higher octane fuel for that resistance.

gjestico

iTrader: (5)

Sooo what we are really asking is how much more hit you need to get a 9.9x

speedtigger

iTrader: (16)

No. I have plenty of fuel volume. This discussion is about octane and cost to get it.

My car has a 20 gallon fuel tank and I live 70 miles from the track. And, because of the design, the tank has to be nearly full for the pump not to suck air under acceleration. You don't want to know what I spent on fuel this last weekend.

Many say I can ran a 150 shot on pump gas no problem, and I may do that, but I just want to be safe as possible.

3pedals

iTrader: (3)

If you run a dedicated fuel tank for the nitrous, can you put 2 fittings on it, and swap the supply line for the carb fuel system once you arrive at the track? - so that the carb and nitrous fuel systems have the good stuff? Or plumb some valves In so you just open/ close , and your converted?
About the ~.090". Nitrous fuel jet, it has full fuel pressure, the carb jets are flowing under the depression created by the carb boosters. I think the nitrous fuel jet moves alot of fuel comparatively . Jmo

speedtigger

iTrader: (16)

I like the idea of the small dedicated tank with the valves. That way the motor is running on the good stuff too.

You may be right about the nitrous jet being under pressure.

xpndbl3

iTrader: (23)

way over thinking this. Run the tank low, pour in 5 gallons of 110 and let it eat. Or just run a dedicated tank for just the nitrous side of it. One gallon of leaded fuel in a nitrous tank will last quite a long time.

speedtigger

iTrader: (16)

I cannot run my tank low. These old 64-67 A-bodies have a 20 gallon tank that is flat as a pancake with the pickup near the front. So, if it is not almost completely full, it uncovers the pickup under acceleration. As you know, fluctuating fuel pressure on the juice is NOT an option.

Also, I spent some time on the phone with both Sunoco and VP. I learned that specific gravities and burn rates vary significantly from fuel to fuel. With the exception of VP-100 and Sunoco's GTX-260 (100 octane). You will need to re-jet to maintain your tune.

For those mixing in your tank, the big nitrous guys warn that if it is not mixed 100% and you get a snort of pump gas on a 110 or 112 tune, bad things could happen.

xpndbl3

iTrader: (23)

so run a dedicated cell up front then for nitrous with 110, or do what 99% of racers do and weld a sump onto the back of your tank for fuel pickup. The big nitrous guys aren't running a 150 shot, and we've switched fuels from 110 to 113 to NO2, etc and not really messed with the carb tuneup since it's done with the nitrous jetting for each power level. Now running too much octane with slow the car down, but this isn't at the level you're planning on running.

speedtigger

iTrader: (16)

For my car, I think the first thing I want to do is build a custom baffle and pickup to solve the fuel control problems in my factory tank. Ultimately, I would like to have a 3 to 5 gallon cell in the trunk with valves. When I get to the track, I just turn the valves and run off of the racing fuel in the cell.

I am pretty sure I can just run my set up with nitrous on pump gas, I just like the safety margin of some good fuel.

likes cars

I welded in a sump on my bottom rear A-body tank and plumbed the filter and pump from the back. It was a bitch to wled. The galvenized paper thin tank needed 2 careful passes tig with stainless then one with bronze silica, then silver solder to keep it airtight. I did so at the advice of a drag racer who indicated exactly what you described.

RsSean

iTrader: (27)

I run 116 in my standalone and the 93 pump gas in the main gas tank. Have not had a single issue mixing gases. I use the 116 to give a more "buffer" room while the car is on the jug. The 116 will take out the wideband sensor time to time.

speedtigger

iTrader: (16)

Did you seal the tank after you welded in your sump?

likes cars

Seal it? Like with that green snot stuff? No. Left it bare inside. I hope that isn't an issue. I also neglected to cut the circles in a baffled type pattern with a hole saw. I just cut the rectangle and overlapped it with the kit. The original tank was pristine inside by the way. Not a hint of corrosion. The sump might corrode over time, dunno for sure.

speedtigger

iTrader: (16)

The tanks are galvanized from the factory. When you weld on it, it burns off the coating. It can rust where the welds are and the untreated metal of the sump can rust too.

Some guys coat their others don't. Some guys say as long as you leave the tank with fuel in it it won't rust. I have not done mine yet. I haven't decided if I am gonna coat it or not.

xpndbl3

iTrader: (23)

that coating can flake off inside the tank. No reason with a good TIG welding job and always having 1/2 gallon of gas in the tank to worry about rust forming. We have sumped tanks that were done in the mid 90s and are still fine.

ZONES89RS

iTrader: (25)

Exactly, the outside is the issue. Not the inside. From my experience anyway.