In my thermodynamics class we dabled with a GM Quad 4 on a dyno. We were using the Otto Cycle and comparing it to actual analysis from the dyno and calcs. One of the parameters we found was the BSFC (brake specific fuel consumption) i found this one pretty interesting and was wondering if anyone knew what the LS1/LT1 has for BSFC. Also if anyone has a P-v diagram i would also like to check that out if you don't mind.

thanks

 

BSFC will vary depending on how efficiently the engine makes power. At hp peak you might see BSFC's from over .500 to under .400 depending on engine mods.

How about a homework problem?

Calculate the BSFC for a Winston Cup car runing at Daytona's 2.50 mile track with the following conditions:

450 flywheel hp. Engine runs WOT all the way around the track (driver never lifts) and rpm stays within about 300 rpm band where hp curve is essentially flat.

Average speed is 180.00 mph. No caution laps, and our car is the leader running in clean air.

Fuel has a specific gravity of .735

Fuel cell is restricted to 13 US gallons. Crew chief wants to pit with 1 gallon remaining. Assume that extra fuel used to accelerate to speed is saved during decel and pit in.

Pit window is 30-31 laps.

What's the BSFC range? Let's go for 3 significant figures.

 

.380 to .392?

Andris

 

That's just what I got.

Low BSFC is critical for endurance racing like this, unlike drag racing.

KRAZY4TA, did you do your homework?

 

LOL

 

KRAZY4TA- I'm curious what #'s you got on the dyno with that quad 4 (bsfc, hp, torque..., I've always played with the idea of messing with them.

Andris/OldSStroker- wanna share how you got that #? I think I've just been up too long but I can't seem to wrap my head around that problem right now (and off the top of my head I don't know of a specific formula dealing with it).

 

BSFC is the lbs of fuel burned per horsepower. You need to figure out how much fuel is used.

180 mph / 2.5 mi = 50 seconds per lap
30 laps = 1500 sec = .4167 hrs for 12 gallons
28.8 gallons/hr

1 gallon race fuel * spc grv fuel/spc grav water = 45.864 lb/ft^3
Convert cu ft to gallons, and

1 gallon race fuel = 6.1311 lbs

1 hr = 28.8 * 6.1311 = 176.576 lbs

BSFC = 176.576/450 = .392

I forgot much of the simple stuff from school, so in about 10 minutes of internet searching, got the specific definition of BSFC, then since I leave my machinery's handbook at work, I needed to convert specific gravity to lbs and gallons to lbs (internet to the rescue again!). I'd have to say the one thing an engineering education gives you is the ability to forget everything, but find what you need in short time

Andris

 

You first have to understand it though, which you do.

Want your grade?

B

Why?

BSFC is lbs of fuel per hp per hour. That makes the units work out.

Wt. of fuel = sp. gr. of fuel (.735) * density of water (sp. gr. is unitless)

We learned the "unit cancellation" method to derive conversions and help assure the calculations were the right ones. I remember very few formulas, but a few magic numbers remain in my head. I still think in English units, but in metric, H2O is 1 gm/cc (@20C and 1 atm which is close enough to race conditions at Daytona in Feb!).

Thanks for playing.

 

Just a side note:
I believe that a "pair" of Quad 4's in a cigar-shaped vehicle set a world speed record years ago. The Quad 4 was G.M.'s attempt to build a highly efficient engine that could produce hp and torque nearly what a small v-8 could produce. There was an article with pics in a G.M. magazine where someone built custom exhaust to twin turbos on a Quad 4 and produced in the range of 740+ FWHP! I've owned several, and I can attest, when running correctly, they are relatively fast...

 

Jim Feuling produced the 1270 hp 2.0L Quad 4 which powered the Aerotech Olds. There was a 750 hp version also. Your post is ironic, as Jim recently passed away.

http://www.landracing.com/news/feuling.htm

Here's the car. It went 257 mph on a closed course:

http://www.geocities.com/MotorCity/8.../aerotech.html

(You might have trouble pulling this up.)

Here's more on the Q4:

http://www.sunfiregt.net/articles/ar...quad_mods.html

 

Thanks for all the detailed info. He was quite a guy. To your knowledge, are those four patents the only ones credited to him? With the designing of Harley's Evolution engine and centerfire 454 heads and fastburn technology, I would think that he would have had a box full of patents...

 

I wish I would have known about this before I wrote the report. HAHAHAHA

Hey KRAZY4TA, what lab section are you in? I'm in the Friday 1:30 class with Joe.

 

1LEThumper i'm in your class man haha. in class i'm known as Womac. see ya friday man.