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914World.com _ 914World Garage _ costs money to go fast

Posted by: Triaddave Sep 25 2005, 11:23 AM

O.K. so i built this big four banger. a 2.4 l,big bore four. all the goodies,rad cam,big valves,dual springs,103mm pistons on stock stroke rods.lightened flywheel and 44idf webers. the engine wouldn't run on the 50 mains, but the 60's seemed to make it screem. and screems it does! great low end tork and the top end comes up fast.
the engine is great, but the mileage sucks. i put 8 gals for a day at the race track.usually plenty for the drive up and back, two drivers with fun runs. so hear it is, low on fuel at 100 miles! less than 10 to the gal,more like 8 something. do i have a issue going on? the engine seems to run like a raped ape,but i expected a bit more on the mileage dept. any ideas?

Posted by: bd1308 Sep 25 2005, 11:49 AM

isnt there a main between 50 and 60?

try that

Posted by: Triaddave Sep 25 2005, 11:53 AM

sure there is, like 55's. i was limited to what i had in stock. but i'm not sure that the mains are the problem.i'll pull out the plugs today to see how they are burning. i did have a issue before race day with the manifolds coming loose at the heads,fixed.

Posted by: bd1308 Sep 25 2005, 11:56 AM

i figured that isnt the solution.......

b

Posted by: dmenche914 Sep 25 2005, 11:59 AM

14 mpg in a 3.8 liter V6 powered 914 with Holley 4160 headers, cam, and a slightly heavy foot.

Posted by: J P Stein Sep 25 2005, 12:21 PM

I went thru about 3 gal in 10 passes at an SCCA AX practice event....and ran out on that 10th.

Posted by: rhodyguy Sep 25 2005, 12:54 PM

hard charging dave. i bet with regular driving you would see better mileage such as on the freeway. i think i get in the upper 20's on the freeway just cruising. zipping around town in 3rd results in $40 fillups on a regular basis. you may have to install a bung on the final someplace and run an 02 sensor/gauge to figure where the A/F mixture is at.

k

Posted by: Aaron Cox Sep 25 2005, 12:56 PM

Dave - what are some specs on the motor?

bore/stroke etc

Posted by: redshift Sep 25 2005, 01:04 PM

Bigger than your's.. all you need to know.

M

Posted by: rhodyguy Sep 25 2005, 01:12 PM

103x71 aa. a bit of confusion. you mean 50 & 60 on the idles? pull the main stack and check the numbers on the main jets, should read 1xx something, air correction and the emulsion tubes also.

k

Posted by: olav Sep 25 2005, 01:26 PM

I get about the same gas mileage too.

55 idle and I forget my mains.

Goes like stink though.

If I drive in 5th everywhere I can get 200 out of a tank.

Posted by: Brando Sep 25 2005, 01:35 PM

Triaddave... did you forget you have a 5th gear?

I can believe that low of mileage on a 2.4... Do you drive it in the high RPMs all the time? With the 44s open all the way, you really can flow a lot of air/fuel through there. If you keep it at 3000 - 3400 rpms when crusing you should see a lot better mileage.

Your motor sounds hot... I need new undies.

Posted by: rhodyguy Sep 25 2005, 01:47 PM

+, must be 100miles round trip just driving to bremerton and back. they run quite long courses at bremerton, with lots of 2nd gear. 2 drivers=6 passes (minimum) + fun runs. wide, sticky ax tires. long line ups and idling if you don't shut it down. a bit of stop and go from your place to I-5. it adds up. not surprising that the milage seems low.

k

Posted by: URY914 Sep 25 2005, 01:51 PM

I use to go through gallons and gallons of gas when I did track events.

I mean you're on the gas to the floor or on the brakes to the floor.

What's want?

Posted by: rhodyguy Sep 25 2005, 01:54 PM

the triad crew are all "on throttle" all the time.

k