Accurate Injection Posted April 30, 2007 Share Posted April 30, 2007 Can some one gives us some MPG Feedback Please? Like to know what others are getting on a bone stock L28 with EFi, and what someone is getting on a relatively stock L28 with Triple Webers? Interstate driving running 75 to 85mph with A/C going would help too! Thanks Guys! Quote Link to comment Share on other sites More sharing options...
cpt jack Posted May 1, 2007 Share Posted May 1, 2007 with my efi an no ac i get around 20-22ish highway and any where from 10-15 on streets.... Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted May 1, 2007 Share Posted May 1, 2007 Ow boy I'm soooooo looking for 10-15mpg around town lol. Quote Link to comment Share on other sites More sharing options...
Accurate Injection Posted May 1, 2007 Author Share Posted May 1, 2007 Hey Guys that's what we thought!!!!!!!!!! The 5 hour trip up to Road Atlanta and back! Out on the Interstate running 75 to 85 MPH, we got 25.3 and 25 .1 MPG!!!!! My Buddies 510 with L20B, header and 32/36 Weber only got 27 MPG and that was with the DAMN A/C running the whole time! We were running the Precentage Range of the base fuel MAP real Lean! Not to the Point of lean misfire, but you could feel the floor board and see engine temp gauge climb, but never had a Misfire. with a 160 degree Thermostat the engine would run in the 180 range according to the Laptop and Data Logs. This had nothing to do with our ITB's just the Mapping of the ECU, we thought it was extreamlly good MPG for a set of Triple Side Draft ITB's. We are running the stock EFi Heat shield between the header and the ITB's, and both are painted with VHT Header Paint that seems to be WELL STUCK now! Shame the Company Injection Logic did not make it to Market........ the software was killer! Kevin Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted May 1, 2007 Share Posted May 1, 2007 I've hit 28 mpg with the STOCK EFI on my 78 280z (early 5 speed swap with a 3.54 rear). Bumperless, lowered, and only seats and a dashboard (plus luggage cuz I was moving into my dorm) probably cruising 85mph. With the 4 speed, I've gotten 22-24 highway cruising at +4.5k rpms (I really want a 5 speed again!). City I've gotten low 20s before, but now my driving style and the 4 speed keep it around 16 city I think 1 fast Z has hit ~30mpg (maybe more) with megasquirt and ITBs running very lean at highway cruise. I think Tony D has posted about some nice numbers from webers either here or on zcar.com. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted May 1, 2007 Share Posted May 1, 2007 The highest MPG I have seen with a Z was 30mpg on an L28 with absolutely perfectly tuned SUs and a ZXT 5 speed. That guy was an older gentleman with a lightly modded Z. He knew his way around those SUs!!! I get about 16-18 MPG with my 9.2:1 L26... but most of the time I am getting about 8mpg because of that pesky ultra-lightweight pedal...or is it a heavy foot? Quote Link to comment Share on other sites More sharing options...
Accurate Injection Posted May 1, 2007 Author Share Posted May 1, 2007 Thanks for the feedback guys! THe 25 we got was the best the testbed had ever seen, so I'm sure we could have leaned it out a liitle more! Still not bad when ever now and then open it up to hear the Triples Scream! LOL! Kevin Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 2, 2007 Administrators Share Posted May 2, 2007 ’75 280 Z, 2700 lbs, lowered a little, stock dished piston L-28 short block, stock EFI, stock cam, header, and my port work, recurved ignition advance, Jacobs ignition coil and wires, lightened flywheel, early 5 speed, 3.54 R-200, 195 60 HR 14” tires, I recorded several 30 MPG runs between Medford and Eugene up and down I-5, (170 miles one way), with the dual 1.75” exhaust, and when I switched to dual 2”, my best freeway MPG dropped to 28 MPG. Car ran consistent 0-60 MPH in 5.7 second and ran the 1/4 mile in 14.4 @ 97 MPH, this was back in the mid ‘90’s. Quote Link to comment Share on other sites More sharing options...
jknc90 Posted May 3, 2007 Share Posted May 3, 2007 Is ~10 MPG right for a stock 1972 240z? (PM me so I do jack the tread since its mainly about L28's) Thanks guys Jon Quote Link to comment Share on other sites More sharing options...
Challenger Posted May 3, 2007 Share Posted May 3, 2007 Is 10 mpg driving conseratively? BRAPP- How were you running 14.4 with a virtually stock engine? Not disputing it but It seems really quick. Whats the rpm on the freeway for a 280z 4spd 3.54? Im guessing about 3200 RPM.?.. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 3, 2007 Administrators Share Posted May 3, 2007 Is 10 mpg driving conseratively? BRAPP- How were you running 14.4 with a virtually stock engine? Not disputing it but It seems really quick. Whats the rpm on the freeway for a 280z 4spd 3.54? Im guessing about 3200 RPM.?.. For stock EFI and a stock cam and stock 2†throttle valve, (the throttle shaft was profiled), The car was pretty quick and ran hard. (This is the same daily driver 280 Z that received a very mild SBC that ran 12.3 @ 113 MPH on street tries). With the L-28, it fought for traction through all of 1st gear with just throttle application, and in 2nd gear you could coax wheel spin with the clutch. It did have a nice header with 1 5/8†primaries, originally ran a dual 1 3/4†exhaust then made it dual 2â€. I ported the N-47 head with extensive valve unshrouding, recurved the distributor and over a period of 4 years tuning and fiddling with AFM, water temp resistance, and ignition timing, (I ran a BUTT load of ignition advance in that 8:1 compression ratio L-28), I had it running in a pretty good state of tune, again for a stock cam and stock EFI system that is. Several members on this forum have ridden in and driven the car during that time, Ron Tyler, Savage42, burrl, tube80z, Dave Lum of http://www.datsuns.com, and a few others. It was impressive, but only from the standpoint of the stock cam and stock EFI system. Compared to mildly built and properly tuned set ups with better breathing induction systems, bigger cams, stand alone EMS or carbs, my L-28 was just ho-hum. Pretty much any L-28 powered street Z is capable of running Low 14’s and even 13’s with aftermarket injection, aftermarket intake manifold, a nice bumpy stick under the cam cover, (of course headers, exhaust, lightened flywheel), and some time getting the set up totally dialed in. There are MUCH quicker N/A L-6 powered Z cars on this forum, I can think of two that run in the high 12â€s in the 1/4 mile, N/A! Norm and 1-fast-z are both running 12.8 N/A! Norm is doing it on SU carbs, 1-fast-z on a custom built intake manifold and Mega Squirt EFI. Any how, here is a pic of my mostly internally stock L-28 engine… Quote Link to comment Share on other sites More sharing options...
Challenger Posted May 3, 2007 Share Posted May 3, 2007 For stock EFI and a stock cam and stock 2” throttle valve, (the throttle shaft was profiled), The car was pretty quick and ran hard. Thinking that you did a slightly modified NA L28 and got into the 14's makes me want to go towards a NA motor. Ive always wanted to get my car once its finished into the 14's turbo or NA. About how much power would you need to counter the difference in 2700 lbs to about 3600lbs (what my cars vin tag says)? Once the cars finished Ill try to get as much weight out as posssible. You said you had stock EFI but had a different manifold. Did that change much? Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted May 3, 2007 Share Posted May 3, 2007 Whats the rpm on the freeway for a 280z 4spd 3.54? Im guessing about 3200 RPM.?.. Closer to 3.5-3.6k at 75mph (highway in AZ). Mario Quote Link to comment Share on other sites More sharing options...
jknc90 Posted May 3, 2007 Share Posted May 3, 2007 Is 10 mpg driving conseratively? somewhat conservatively lol. i actually think I might have figured it up wrong. I need to check it again to make sure. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted May 4, 2007 Share Posted May 4, 2007 On the Highway around 30 MPG for my first 240z. Got better than that going across Texas drafting a moving van on the same trip. Got 26 mpg on my 260 across Calif flat lands. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted May 5, 2007 Share Posted May 5, 2007 My N/A L28 flat top block, w/SU's header,N42 head w/cam, with a 9.2:CR, 2.5 exaust, zx dizzy, 5 speed trany, 3:54 rear end, gave me 26 MPG on a 1,000 mile road trip to norther california and back. I think I was a little lean but there were no engine problems. Around town I get about 16 MPG unless I get into the throttle. Matt- Quote Link to comment Share on other sites More sharing options...
Accurate Injection Posted May 5, 2007 Author Share Posted May 5, 2007 I guess we are feeling pretty good with 45mm ITB's, with 1 or 2 "Lets here the trumpets sing" thrown in for good measure! With 18 degrees of timing it runs to 6500 rpm real strong! Kevin Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted May 5, 2007 Share Posted May 5, 2007 On my last two tanks I've been getting 20-21mpg "in town". Never taken this guy on the highway. By "in town" I mean driving about a mile to the loop, maybe 3 miles at 60-65 on the loop, then another mile of stop and go to get to work. Occasionally I go somewhere else in the car and the 20mpg time I let my wife practice driving the stick in residential for about 30 minutes. I have been pleasantly surprised at getting this good of mileage because previously I was getting 15-17 on the same commute and that's what I always got with my other L28 before killing all hopes of good gas mileage in that car with a carbed 383 and no overdrive. My current L28 has a P90a head supposedly shaved God knows how much, E30 cam, 18-20* initial timing with no vacuum advance (which would help more maybe), and a single 2.5" no cat magnaflow muffler. I also have an open element air filter in stock location. Quote Link to comment Share on other sites More sharing options...
jknc90 Posted May 10, 2007 Share Posted May 10, 2007 I checked my MPG again and I had done it wrong somehow, anyway I get around 16 MPG, not 10 lol Quote Link to comment Share on other sites More sharing options...
myplasticegg Posted May 11, 2007 Share Posted May 11, 2007 Thinking that you did a slightly modified NA L28 and got into the 14's makes me want to go towards a NA motor. Ive always wanted to get my car once its finished into the 14's turbo or NA. About how much power would you need to counter the difference in 2700 lbs to about 3600lbs (what my cars vin tag says)? Once the cars finished Ill try to get as much weight out as posssible. You said you had stock EFI but had a different manifold. Did that change much? Your vin tag gives the Gross weight. For a 2+2 that includeds 4 people and luggage, maybe a dog to disney world. Need to put your car on the scales to find out what it weighs Quote Link to comment Share on other sites More sharing options...
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