280zwitha383 Posted July 12, 2007 Share Posted July 12, 2007 Oooooh, forgive me for typing primaries instead of secondaries (do you really not think I know the difference?). Come one. Does it not even make sense in my post that I made a typo? Quote Link to comment Share on other sites More sharing options...
Z48LT-1 Posted July 12, 2007 Share Posted July 12, 2007 280/383 Heck yes, I knew that's what you meant, and I'm just an fng. Nobody who's ever been introduced to a quadrajet would get that wrong. And not just because you're a fellow Texan... Best -- Gary Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted July 12, 2007 Share Posted July 12, 2007 areas you can improve easily change your driving style and carefully keep & maintain average engine rpms UNDER 3500rpm, watch well ahead and anticapate useing brakes, accellerate slow and steadly, yeah! no fun but much better distance per gallon. take all un-necessary weight out of car, carting around a trunk full of heavy junk hurts mileage, think about what your doing ahead of time, make one or two trips vs 3-4 youll need too do if you forget something on the first trips, plan your routes, bouncing all over the place at random and back tracking, is seldom efficient vs a planned route, make a list and check off each item you need, before you drive install a vacuum gauge and watch the needle, it will indicate a good deal about fuel/air flow rates increase tire pressure=lower roll resistance swap to taller tires= more distance per engine revolution in gear swap to low restriction air filter= engine tends to breath easier, yeah! there cam be an easy extra few mpg in a good low restriction CLEAN filter VS a poor dirty air filter swap to 10w 30 synthetic oil-lower engine drag/friction try to stay under 70mph max things that require major work swap to od-trans-lowers average rpms and a/f use swap to fuel injection=much more effective f/a ratio control swap to msd ignition= slightly better burn and lower crud build-up in most cases install small dia. headers and large dia, low restriction exhaust, = this tends to increase low rpm tq and reduce engine pumping losses a clutch fan, or electric radiator fan tends to reduce engine drag losses yes there are a few things that can be done to reduce air drag, look for them, things like an aluminum air deflector panel under the radiator MIGHT reduce drag, tucking your exhaust up tight to the frame might help ETC. engines usually get thier best mileage near a 14.7-15:1 a/f ratio, best power near 12.6-13:1 the differance can be several miles per gallon engines tend to run efficintly at 190F-210F coolant temp,and at about 215F-220F oil temp, run to hot or too cool and youll waste fuel if your using a carb,the better designed DUAL plane intakes tend to produce better low/mid rpm tq allowing better mileage that a single plane intake which tends to require higher average rpms. check your ignituion advance and plugs, get the ignition timing screwed up and youll lose mileage. btw a second car(small 4-6 cylinder manual trans parts chaser truck) can be a big plus on your fuel bill vs running your sports car with a 450hp v8 on side trips, for years I had a datsun truck as a parts chaser, and while it was not the height of style it got 20 plus MPG and over 280,000 miles before I finally sold it! Quote Link to comment Share on other sites More sharing options...
icewtr Posted July 12, 2007 Share Posted July 12, 2007 Wow!! that was alot to read ..lol good post... i think..... and hey i have an automatic with a 383 nice power and get about 24 mpg on highway .... And now city ..depends .. like was mentioned earlier .. how ya drive it .... if i take it slow i have done that for a full tank and been around 17 to 19 city .Normal driving .. as in getting on it here and there to stomp the mustang or vett here and there i see about 12 to 14 .. When i am running on the street with the 700r4 ..354 gears and a 215/70/14 rear tire and 205/60/14 up front skinny tires and about 38 for the pressure .. and i don't daily drive this thing but i could if it was not over 100 out here and i had ac...... Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted July 13, 2007 Share Posted July 13, 2007 24mpg with a 383/700r4/3.54 rearend?! Nice Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted July 13, 2007 Share Posted July 13, 2007 Oooooh, forgive me for typing primaries instead of secondaries (do you really not think I know the difference?). Come one. Does it not even make sense in my post that I made a typo? Darn, I tried not to make it personal; looks like I failed again. We have quite a few young members, some of whom wouldn't know a Stromberg from a Weber having grown up around fuel injection. They are a big reason that I feel our technical posts should be accurate. To answer your current question: NO, your original post didn't look like a typo, as you went on to say a Quadrajet might equal a two barrel's mileage in light driving. (I personally believe that a properly tuned Quadrajet should be able to better a two barrel's mileage due to those tiny primaries and the low power level required for plain cruising). As to your personal expertise... For all I know, you may be like Grumpyvette, and know pretty much all there is to know about cars. Assuming that to be the case: Proof read your posts! And no, I won't sue you over it. <> Quote Link to comment Share on other sites More sharing options...
k3werra Posted July 13, 2007 Author Share Posted July 13, 2007 update: well from the looks of it i think im going to go with a smaller displacement and a supercharger system for extra power if i cant get to 300hp. i really dont want to drive to the point where the experience is so sedate...when i drive this i want to be engaged. ill mainly be using this article and the advice ive gotten so far and the books ive ordered http://www.hotrod.com/techarticles/302_small_block_chevy_dyno_test_tune/index.html Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted July 14, 2007 Share Posted July 14, 2007 To answer your current question: NO, your original post didn't look like a typo, as you went on to say a Quadrajet might equal a two barrel's mileage in light driving. (I personally believe that a properly tuned Quadrajet should be able to better a two barrel's mileage due to those tiny primaries and the low power level required for plain cruising). Your point is well taken concerning the Q-jet (in my simple mind I never would have thought a 4 barrel could get better mileage than a 2 barrel but it makes sense even though it might not be realistic). However, how could a carb with huge primaries (as I improperly stated) ever come close to a two barrel? That makes less sense than thinking that a person thinks that a Q-jet has huge primaries. People make mistakes. No reason to imply that they shouldn't be posting. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted July 14, 2007 Share Posted July 14, 2007 If I was going to build a lightly boosted sbc, I would start out with a late model 350 block that already has a roller cam (they handle the added pressure better than a flat-tappet cam) and go from there. That's just my opinion. Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted July 14, 2007 Share Posted July 14, 2007 Your point is well taken concerning the Q-jet (in my simple mind I never would have thought a 4 barrel could get better mileage than a 2 barrel but it makes sense even though it might not be realistic). However, how could a carb with huge primaries (as I improperly stated) ever come close to a two barrel? That makes less sense than thinking that a person thinks that a Q-jet has huge primaries. People make mistakes. No reason to imply that they shouldn't be posting. You are correct... it didn't make a lot of sense; that was basically the problem. I like HybridZ a lot, and the people on it who make it what it is; I've no desire to shut down anyone's posts. At the same time, I strongly believe that technical posts need to be authoritative, so the information here can be counted on. (Because of that, you won't find me trying to troubleshoot fuel injection problems for folks: I don't know Diddley about FI or many other things). I also make my share of mistakes; when you find one, call me on it. No harm, no foul. Peace. <> Quote Link to comment Share on other sites More sharing options...
d-phlip Posted July 14, 2007 Share Posted July 14, 2007 How would you make a 350 v8 with mild hp (320-350hp) get better mpg? from what ive read changing to FI and manual tranny (5sp/6sp). what else have you guys with 350's done to make your setup yield better mpg? I have a 72Z that had a 350 with mild roller cam, aluminum "trick flow" heads, MSD ignition and Holley 750. I had a 3.73 rear and 700R4 trans. P295/50-15 rear tires (26.6" diameter) No matter how I drove it or tuned it, I seemed to get 10 - 12 mpg. I finally gave up. I bought an LS2 crate engine, along with new T56 trans. (ViperRedLS1Z did the install). Now I get 18 - 20 mpg. It is an expensive upgrade, but the economy, power and driveability are significant improvements. The trans has the 0.5 overdrive 6th gear, and I never use it with the tall tires and rear gearing. I am thinking of going to 4.11 rear gears which I don't think will hurt the gas mileage. Good luck with your project. Dave Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted July 15, 2007 Share Posted July 15, 2007 You don't use it?! Why not? Quote Link to comment Share on other sites More sharing options...
Mitch Posted March 26, 2010 Share Posted March 26, 2010 (edited) opps.. im tired and misread the posting... disregard Edited March 26, 2010 by Mitch Quote Link to comment Share on other sites More sharing options...
dustin280zx Posted March 29, 2010 Share Posted March 29, 2010 (edited) Most guys on here will tell you that they didn’t install a V-8 into their Z cars to get good mileage. Good fuel mileage is what their Nissan Sentra or TDI Jetta is for. I have a blow-thru sbc turbo setup and I get about 8-10. I went the TDI jetta route as it was cheaper than switching to a standalone. On a serious note there are a few articles in Hot Rod and CHP about testing a properly tuned carb setup to a holley, edelbrock, and accels FI conversion. If memory serves me correctly they experienced a 1-2 mpg increase over a carb. Think of all the fuel you can buy for the cost of one of these. If I didn't already put the magazines in storage I'll give you the month it was in and tech article name so you can read it online. Edited March 29, 2010 by dustin280zx Quote Link to comment Share on other sites More sharing options...
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