EFI conversion for 454 GM motor. Anyone done one ?

I have purchased a Airstream Argosy with a 454 GM motor. I love the coach for its beauty and retro aircraft style. ( Im a pilot) but, to my point and question. I am looking for anyone who has done a conversion from a Carburetor to a throttle body EFI ( electronic fuel Injection) There are several manufactures that now make a drop in bolt on kits starting at around 2 grand.

The benefits include better fuel economy , easier starting and reliability. The long term benefit is an engine that will last much longer than a typical carb based power plant. Precise air fuel metering will minimize cylinder washout due to a to rich mixture which also results in oil contamination and valve train damage due to to lean. 

In aircraft racing we have been converting automotive engines that were normally carb based to EFI and have realized fantastic benefits in power and reliability. Cooling running engines as well and those are all very important in the air. 

Several companies are now making bolt on kits. Holley, Edelbrock, MSD and Fast EZ EFI to name a few. 

I would like to open the floor to discussion and here from some who have actually done an EFI conversion and what they experienced and what they recommend. Or any other experiences and thoughts. 


77 Airstream Argosy

Views: 5959

Tags: RV 454 GM engine modifications, how to get better gas mileage in an RV, rv throttle body EFI ( electronic fuel Injection


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Comment by Ralph Javins on June 21, 2015 at 3:43pm

Good morning, Jeff York; 

     It has been a while since this topic was initiated.  I am surprised that there are no reports on the effects of the efforts. 

     I am also engaged in some modifications to improve fuel consumption.  Mine consists of a three step process at this point with the main goal of improving the overall system to allow it to pull an overdrive.  I believe that the overdrive coupled with the improvements to make that practical will result in some reduction in the fuel consumption. 

     The three main things underway right now are the replacement of the GM HEI ignition system with another distributor with a Hall Cell ignition trigger system feeding a CDI or Capacitive Discharge Ignition box, the installation of a Gale Banks Engineering "PowerPack" kit which is mainly a stainless steel header and exhaust system (the part now underway) to be followed then by the installation of a Gear Vendors 3D0475  22% OverDrive behind the GM 3L80 three speed automatic transmission.  The delay in getting the exhaust system converted has been mainly due to the need to modify the exhaust system for such things as having welded into the headpipes the Oxygen Sensor bungs or mounts for fitting the O2 Sensors to work with a feedback control system driving a TBI EFI system, if that fourth step (the TBI EFI system) is determined to be really worth the expense and effort when the first three parts are completed.   The Quick Fuel Technology (another maker for your list) TBI EFI system is almost as expensive as the Gear Vendors OD unit.  Having the modifications to the exhaust system made now before it is installed seemed to be a good idea in preference to taking the exhaust system apart later for the welding of the O2 Sensor buns then.  It does seem that it always takes much longer than you thought it was going to be when you are making modifications to the modifications. 

     Another use for the O2 Sensors will be monitoring the control of the air/fuel mixture as provided by the original Rochester QuadraJet carburetor using one of the Equus meters. 

     The effects of each modification or addition is being tracked by the GPS navigation system in the motor home with its automatic fuel economy routine.  I chose to use that method when I discovered that the odometer in the motor home was about 10% optimistic; I was not really going as far as it was indicating.  The unusual thing is that the speedometer section in that instrument is rather accurate in comparison with the GPS unit.  There just seems to be this discrepancy with the miles actually traveled.  That is why I am using the GPS box for that part. 

     The TBI EFI system may be fitted later after the three main modifications are completed.  I do not really expect to seen any real improvement in the fuel economy of the TBI EFI system over a clean and well adjusted Rochester QuadraJet carburetor under most conditions.  The main advantage I can see that the TBI EFI system has is its ability to automatically adjust the air/fuel mixture as necessary for changes in altitude such as when crossing mountains.  Then I think that there can be a real advantage.  I probably will do that, but it may be a little while later.  Perhaps this Fall or Winter. 

     With the fuel economy (?) checks that I made before beginning this project, my normal consumption was in the 7.5 to 8.5 MPG range on level ground down here, and down to about 5.6 MPG in crossing the Cascade Mountains.  I am sure that I can get to 10 MPG, and it is possible that I might approach 12 MPG.  We will see the results when this project is completed. 

     One thing that I should say now is that I do not expect this series of modifications to "pay for itself" with any savings in fuel.  The costs of all these things are not inconsequential.  This is more just something that I am doing to see if it can be done. 



          Latte Land, Washington 

Comment by John "T" Nordhoff on October 13, 2014 at 10:54am

 This topic really interests me as a user of big block V8's for nearly 30 years BUT NEVER GOT 10 LET ALONE 12 MPG even after Gerharty Performance RV in California fine tuned BOTH my carb and distributor and I upgraded to dual 2 1/2 free flow exhaust and headers and even in rigs with an Overdrive grrrrrrrrrrr lol. There was a post a few days back by a guy talking about getting 12 MPG with a 454 in a Class A Coach who was hoping to get 14. Unfortunately some other gents posted getting more like 6 to 8 MPG (what I also got in many Class A's)  and Id LOVE to get that kind of mileage so keep us posted with your progress WE WOULD ALL LOVE TO GET 12 MPG so if you discover how pleaseeeeeeeeee share.

 I used to consider an after market throttle body EFI on my carb engines but was hesitant to spend like $700 they were back then figuring it wouldn't pay out driving maybe 3000 miles a year. However, I'm glad I waited because each time when I went from Throttle Body to now the Chevy 454 Vortec MPG (but also with Overdrive) has improved each time versus my old carb engines 

 More MPG is a great and fun topic here on RV Forums, keep em coming and if I have anything to contribute I will sure jump in and share.

 Best wishes yall, safe journeys and God Bless

 John T

Comment by Rich Thomas on October 13, 2014 at 10:31am

Hi Jeff, I have a 1977 TravelCraft with the Chevy 350 with the Time tested Q jet 4bbl carb, 400TH transmission with less than 20k miles and was interested in doing the swap as well. Iv'e not done a lot of research but have looked at a few sites, Summit & Jeggs primarily. My dilemma is: is the 37 year old camper worth the investment even with the low miles?. My question to you is have you done this upgrade yet or are you holding off for other options. I notice the last post to be a while ago I hope your still active in your quest?

Comment by jeff york on August 26, 2014 at 9:59am
I have had critisium for having a bored and stroked 454 and expecting to improve fuel economy based on this type of engine. I have heard numbers as low as 4 to 6 mpg yet have stated, my purpose is to achieve a 10 mpg fuel econ. Well, I have been taking my Argosy 28 motor coach on several short shake down trips and I can report that my goal of 10 mog has already been achieved. This on the motors break in and TH400 break in. My plans to continue to improve the mechanicals and Fuel econ are a move to TBI EFI to replace my carb and a 4 speed OD trans such as the 700R4 to gain fuel econ by lowering my cruise RPM from 3000 ish to 2200 which will also keep my engine in its powerband based on the performance cam grind. Now, my goal is to achieve 12 mpg while also getting better engine starts and engine life from the benefits of fuel injection.
Comment by Jimco_W001 on July 18, 2014 at 11:14pm
Hi Jeff,after watching the Hot Rod magazine installation video on the EFI by Fast I really like it.



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