Largest gas tank / hp car (2 hour stint enduro cars)

Hey all, I'd like to get your thoughts on good platforms for endurance race car builds (Lucky dog, Chumpcar ...) We've run Mazda RX-7s for many years and they have a large tank and while a ported rotary could never be considered fuel efficient, we can run a two hour stint on a tank. I'm starting to see more V6 cars and inline six cars show up and I'm wondering what the sweet spots are for hp / fuel capacity and which marques / cars make sense. locally we have a V6 accord, a few BMW's and a v6 swapped Sentra. Wondering if there are other great options.

-Trent

Later Porsche 944's have a 21.7 gallon tank and 160ish HP

C7 and C8 Corvettes are 18.5 gallons.  Thats gotta put them just about the top of the HP/Gas Tank Size.

A 1995 Viper has a 22 gallon tank but they really dont make good horsepower.

S63 AMG has a 21 gallon tank and they make gobs of power.  

Rough approximations I've seen for gallons of fuel per hour at WOT would be in the HP*0.08 for typical gas engines... And more in the range of HP*0.10 for rotaries. If you can use that to figure out an equivalent percent of time at WOT, then you can get an idea of the fuel tank size needed to run 2 hours for an engine of any given hp level.

In reply to TrentO :

Ported rotaries are actually really fuel efficient, at WOT.   Mazda won LeMans due in part to fuel economy.

Are you still allowed to swap a 24 gallon fuel cell in cars with 18+ gallon stock tanks? If so, check some turbo Saabs.

Our GM3800 powered FC RX7 burns about 8.5-9 gallons an hour and we're at the pointy end of lap times.

 

has to be a car? 

Pickemup trucks generally have very large fuel capacity, along with high fuel consumption. But a 20 year old v6 ford or chevy should make pretty good power and have a very large fuel tank. 

All that said, keep the big picuture in mind. Which is to be able to run the most laps in 12/24 hours. IF a larger fuel tank can legitimately save you a fuel stop during the race, then you also have to keep in mind that your other fuel stops may be longer as you have to transfer more fuel. 

I think the real optimization is fuel used/lap time. Which is probably why light 4 cylinder cars do quite well at lemons, usually. 

I remember my dad saying that his '87 T-Bird had a gigantic gas tank. Looked it up, 21 gallons. So there may be an option...

Also... How does 36.5 gallons sound? 

In reply to Robbie (Forum Supporter) :

Do they still have maximum driver stint times?  Seems the optimal fuel tank size is whatever is enough to cover that, plus a safety margin.

SAAB Sonetts have 15 gallon tanks and I was able to regularly pull 32 MPG on the highway. 

WK2 Grand Cherokee has 24 gallon tank. Durango of the same years does too.

RossD said:

WK2 Grand Cherokee has 24 gallon tank. Durango of the same years does too.

If we're going racing with a Jeep, I'd go for a ZJ, not something newer.  Tank is 23 gallons, and the chassis is easy enough to turn into a cheap racecar if starting with a V8 one.  An XJ holds a bit less gas, but weighs less (by almost 1000 lbs) and would have a 4.0, so should burn a bit less.  If it's permissible, I'm pretty sure someone makes a bolt in 30 gallon tank for an XJ that should also fit a ZJ. 

Old large BMWs hold a bunch of gas too.  E38 7 series holds 22.5 gallons with a V8, 25 with the V12.  The older E32 7 series holds even more.  23.8 gallons with a V8, 26.9 with a V12.  XJ40 chassis Jags are up there as well with a 24 gallon tank. 

Unfortunately, save for the XJ, everything I've mentioned above is in the 3900 - 4300 lb ballpark... 

I'll throw a dark horse out there: 240sx. Relatively small 16 gal tank, but they're actually very aerodynamic from the factory

Well, I remember my brother's Gremlin X having a 26 gallon tank, but somehow I don't think that's the answer. 
 

In reply to TrentO :

I replied earlier. 
 The Jaguar XJS has a 24 gallon tank stock. Even the 6 cylinder cars  which are almost as powerful as the V12. But hundreds of pounds lighter and massively more reliable. ( it doesn't intimidate ) 

  It's rated at 200 points by Champ car. Up to 1990 and 300 point after 1990. So you have plenty of go fast points to play with.  
Want more power? Grab a supercharger from an XJR.   And Yes they do came with a manual option ( although rare here stateside) 

Excellent handling, great brakes, plenty of parts.     

TrentO said:

Hey all, I'd like to get your thoughts on good platforms for endurance race car builds (Lucky dog, Chumpcar ...) We've run Mazda RX-7s for many years and they have a large tank and while a ported rotary could never be considered fuel efficient, we can run a two hour stint on a tank. I'm starting to see more V6 cars and inline six cars show up and I'm wondering what the sweet spots are for hp / fuel capacity and which marques / cars make sense. locally we have a V6 accord, a few BMW's and a v6 swapped Sentra. Wondering if there are other great options.

 

-Trent

My recollection is that we never had any problem running 2-hour stints in an e30 325i with a stock fuel tank (14 gal, I think, or maybe it's 16).