lgoodson@pacbell.net Posted November 26, 2009 Share Posted November 26, 2009 What should I expect out of this 93 LT1. It is completely stock except for headers and a 2 1/2 to 3" exhaust with a Magnaflow out back. All smog has been removed. The engine is rated at 275 hp. I have been told that 25 to 28 MPG is possible from a 450 hp LS motor so if so, I should be getting somthing close. The car weighs only 2200 LB. It has the T-56 and the stock 3.36 rear end. So far it seems to be going through fuel pretty quickly but I haven't drove it enough to check it. What are you LT1 guys getting for mileage? Thanks for the input Larry Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 26, 2009 Administrators Share Posted November 26, 2009 (edited) I was getting a smidge over 28 on the highway with my 240. '95 LT1/T56, Hooker headers and exhaust, but otherwise stock, 3.90 gears, and 225/50/15 tires. Car weighed 2420 dry. http://forums.hybridz.org/showthread.php?t=118147 Edited November 26, 2009 by RTz Quote Link to comment Share on other sites More sharing options...
deja Posted November 26, 2009 Share Posted November 26, 2009 On my old LT1 which was completely stock, 130K miles, no smog, headers and cold air intake I got 22 mpg on the highway. I am running a 4L60E auto so I don't have the double overdrive the T56 has. My rear gear was 354. My new engine with the LT4 hot cam and a 370 rear gear gets about 20 mpg. No low weight for my 280Z, 2905 with a full tank. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 3, 2009 Author Share Posted December 3, 2009 Well you guys must be going down hill in 6th gear because I just checked mine for the first time and I got only 14.24 MPG. Ths was at least half on the freeway and the rest around town and the freeway was in traffic but I could drive 60 to 70 most of the time. Now this is a stock 275 hp LT1 with headers and a very loose exhaust system. The rear gears are 3.36 or so I am led to believe. That is what is suppose to be in a 71 240Z manual. I am, to say the least, very dissapointed. I was soooo looking forward to that 22 to 25 mph. Any idea what could be the difference?????. Between your two vehicles and mine. Quote Link to comment Share on other sites More sharing options...
deja Posted December 4, 2009 Share Posted December 4, 2009 You can't really test mileage on one tank full. But it sounds like you may have some issues. Maybe your injectors need cleaned. Did you put in new plugs before the install? In the new engine even with the LT4 hot cam kit and a 3.70 rear gear I have averaged 18.5 in 2600 miles. That includes some really hard city driving and some highway cruising miles. In the old stock 130K engine I averaged 19.1 for 10,183 miles. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted December 4, 2009 Administrators Share Posted December 4, 2009 (edited) But it sounds like you may have some issues. Definitely. 14mpg is pointing to a problem. I'll echo deja's suggestions. Also, what kind of shape are the O2's? Do you know that you're not running in limp home mode? All tune-up related items addressed? Have you done a leakdown on your motor? How are you measuring your mileage (ie odometer correct, etc)? Edited December 4, 2009 by RTz Quote Link to comment Share on other sites More sharing options...
deja Posted December 4, 2009 Share Posted December 4, 2009 Do you have a check engine light? Do you have the OBDI port hooked up? It might be a good idea to pull a scan to see where its sitting. The O2's are a good suggestion. What do you mean by loose exhaust system? Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 4, 2009 Author Share Posted December 4, 2009 By loose exhaust I mean open, unrestricted. I have a 2 1/2" to the Y pipe and then 3" out to a 3"Magnaflow. New O2 sensors and new plugs. Not sure what a leakdown is. My check engine light is hooked up and operating. It comes on with ignition and goes off at start up. The data port is installed. I really tried to do a first class installation with this project so I took no short cuts and did not skimp on anything. I was wondering if O2's could cause this problem. I bought from a vender off Ebay some NTK NGK O2 sensors. I thought they woud work fine but I don't know. They were single wire and they were priced right. $16 each so I went with them. What do you think. Quote Link to comment Share on other sites More sharing options...
deja Posted December 4, 2009 Share Posted December 4, 2009 Sounds like you did everything right. But off market oxygen sensors don't have a good reputation. Stick with GM parts, AC Delco or Delphi. I got my O2s from http://store.getgmparts.com/ AC Delco #: AFS75 GM #: 25312184. LT1 O2 oxygen sensor (93) (non-heated) (AC-Delco #AFS21) = 25166816 LT1 O2 oxygen sensor (94-95) (heated) = 25312184 LT1 O2 oxygen sensor (96-97) (rear heated) (AC-Delco #AFS97) = 25312196 Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 4, 2009 Author Share Posted December 4, 2009 Ok but can the O2 sensors cause this type of problem. Do you Know? Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 4, 2009 Author Share Posted December 4, 2009 Went to that web site and the part number for the non heated was not listed and there was no way for me to search for the correct part so I sent them an email. If that's the problem I will call them. Larry Quote Link to comment Share on other sites More sharing options...
deja Posted December 4, 2009 Share Posted December 4, 2009 I noticed that too. It would be nice if you could search by year and model but you have to know the actual part number. I called them when I bought my fuel pump. He was very helpful and friendly. 1-866-851-0549 Quote Link to comment Share on other sites More sharing options...
Inferno 08 Posted December 4, 2009 Share Posted December 4, 2009 Ok but can the O2 sensors cause this type of problem. Do you Know? O2 sensors can definitely cause bad mileage. If the engine isn't getting correct air/fuel ratio readings from them, it will run rich to protect itself, and as such burn more fuel. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 5, 2009 Author Share Posted December 5, 2009 Got it. Alfedo got back to me today with the correct part number for my engine. ES10966 for $ 17.44. If you guys can think of any thing else for me to check, please let me know meanwhile I'll get the O2 sensors. Quote Link to comment Share on other sites More sharing options...
deja Posted December 5, 2009 Share Posted December 5, 2009 I would get some fuel injector cleaner and put it in the tank with your next fill up. Get some MAF cleaner and give it a good bath (take it off to do that). Make sure your air cleaner is clean and all the connection between it and the throttle body are tight. Take a look inside the throttle body to see how dirty it is. It might be worth pulling it and giving it a good cleaning. Got it. Alfedo got back to me today with the correct part number for my engine.ES10966 for $ 17.44. If you guys can think of any thing else for me to check, please let me know meanwhile I'll get the O2 sensors. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 5, 2009 Author Share Posted December 5, 2009 Heres an Idea. The crankcase vent valve hose running from the right valve cover to the trottle body. I don't have one. I have just a breather on the valve cover. Are you guys using the valve and hose to the TB? Could this be a problem. Checking my Helms manual for the engine where it talks about poor fuel economy, they don't mention O2 sensors to check. Just vacum leaks and spark plugs and bad wires but nothing about O2's. But reading about what they do, I can see how they might make a difference but GM says that they won't, by themselves, initiate a change or make things happen. Waiting for a call back from Alfredo. Probably Monday. The part number that he gave me is not listed on his web site either so I can't order that way. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 5, 2009 Author Share Posted December 5, 2009 Already did the injector cleaner thing right off the bat when I was installing the engine and getting it running. I had the TB off a while back when I was changing the leaky intake gasket and while it was off I cleaned it. It is my policy that what ever comes off this car is cleaned and repainted as necessary before it goes back on. When you say clean the MAF, do you mean the MAP. I have not heard of having to clean it. What kind of product do you use and where do I get it. Is it a common product at the local auto parts store? Quote Link to comment Share on other sites More sharing options...
deja Posted December 5, 2009 Share Posted December 5, 2009 http://www.oreillyauto.com/site/c/detail/CRC0/05110.oap?keyword=maf+cleaner Already did the injector cleaner thing right off the bat when I was installing the engine and getting it running. I had the TB off a while back when I was changing the leaky intake gasket and while it was off I cleaned it. It is my policy that what ever comes off this car is cleaned and repainted as necessary before it goes back on.When you say clean the MAF, do you mean the MAP. I have not heard of having to clean it. What kind of product do you use and where do I get it. Is it a common product at the local auto parts store? Quote Link to comment Share on other sites More sharing options...
deja Posted December 5, 2009 Share Posted December 5, 2009 DOH, you have a 93 LT1 and I don't think that has a MAF! Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 5, 2009 Author Share Posted December 5, 2009 deja, Thanks for the link but 93 LT1 does not have the mass air flow sensor which GM started using in 94. Researching the Crankcase ventilation system. The manual says that internally the engine needs to maintain a vacum pressure and if the Vent system is not there or is not working properly, there could be engine damage. So I guess I will get the parts and see if that helps the fuel economy. Quote Link to comment Share on other sites More sharing options...
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