Carbs Versus EFI
Discussion
Hello Chaps - I know nothing about Fuel Injection other than the basic principles behind it but am keen to learn more in relation to the Small Block Chevy.
I am looking to prepare my GTR for a few endurance events which I hope to complete next year. Last year I competed in a 45 minute race with the Ultima in standard trim and the car coughed and spluttered across the finish line as it ran out of fuel (perfect timing). I would like to increase the fuel economy whilst maintaining the current power so that I could run longer (wouldn’t we all). I have spoke to a few people who suggest a well adjusted carb is just as efficient as Fuel Injection and without the complications. In fairness these people have probably had little experience with EFI on SBC so it may well be a biased view. I would be interested to hear of everyone’s thoughts on benefits and disadvantages of EFI.
I am looking to prepare my GTR for a few endurance events which I hope to complete next year. Last year I competed in a 45 minute race with the Ultima in standard trim and the car coughed and spluttered across the finish line as it ran out of fuel (perfect timing). I would like to increase the fuel economy whilst maintaining the current power so that I could run longer (wouldn’t we all). I have spoke to a few people who suggest a well adjusted carb is just as efficient as Fuel Injection and without the complications. In fairness these people have probably had little experience with EFI on SBC so it may well be a biased view. I would be interested to hear of everyone’s thoughts on benefits and disadvantages of EFI.
Hi Chewy,
There's no denying that EFI offers a more accurate approach to fuelling as it can monitor and adjust according to engine conditions. The disadvantage is that it needs mapping properly to work well and there's quite a few bits that can go wrong (though modern electrics are pretty reliable).
A carb is a simple and can be setup to work very well. However, the setup will inevitably be a compromise, because the fuelling (jetting) is finite.
The factory maintain that EFI is more trouble than it's worth, but who knows. There are a couple of owners on here who run EFI who are far better able to give a real world view than I.
I wanted to go EFI on the Can-Am, but opted to start with a carb as it was simple to get going. Then of course, I sold the car so never got the chance to experiment!
I must say though, running a 'modern' V8 with associated EFI/engine manegement system etc. is a hugely relaxing experience by comparison!
There's no denying that EFI offers a more accurate approach to fuelling as it can monitor and adjust according to engine conditions. The disadvantage is that it needs mapping properly to work well and there's quite a few bits that can go wrong (though modern electrics are pretty reliable).
A carb is a simple and can be setup to work very well. However, the setup will inevitably be a compromise, because the fuelling (jetting) is finite.
The factory maintain that EFI is more trouble than it's worth, but who knows. There are a couple of owners on here who run EFI who are far better able to give a real world view than I.
I wanted to go EFI on the Can-Am, but opted to start with a carb as it was simple to get going. Then of course, I sold the car so never got the chance to experiment!
I must say though, running a 'modern' V8 with associated EFI/engine manegement system etc. is a hugely relaxing experience by comparison!
Thanks Stig
I would love to go down the route of a 'Modern V8' such as the LS7.
The difficulty I have with that is if I wish to race it there are very few series or championships that the Ultima is eligible to enter. The Ultima already raises questions with organisers of major events being a ‘Kit Car’ and a ‘World record holder’.
Dependant on which series I end up in the regulations can be very restrictive on modifications.
I have already experienced changes mid-season in regulations purely for the Ultima in an attempt to slow it down – despite complying 100% with existing regs.
As Ultima don’t offer an option for the fitting of the LS7 this would be an engine other than Original Equipment and may exclude me or put me in a different class. Whereas if it’s a SBC the specification is completely open to the individual. All I have to do is make sure the engine spec combined with vehicle weight complies with the ‘power to weight’ that is a major factor in many championships now.
I was going to post on the thread you mention but didn’t want to hijack it
I would love to go down the route of a 'Modern V8' such as the LS7.
The difficulty I have with that is if I wish to race it there are very few series or championships that the Ultima is eligible to enter. The Ultima already raises questions with organisers of major events being a ‘Kit Car’ and a ‘World record holder’.
Dependant on which series I end up in the regulations can be very restrictive on modifications.
I have already experienced changes mid-season in regulations purely for the Ultima in an attempt to slow it down – despite complying 100% with existing regs.
As Ultima don’t offer an option for the fitting of the LS7 this would be an engine other than Original Equipment and may exclude me or put me in a different class. Whereas if it’s a SBC the specification is completely open to the individual. All I have to do is make sure the engine spec combined with vehicle weight complies with the ‘power to weight’ that is a major factor in many championships now.
I was going to post on the thread you mention but didn’t want to hijack it
Chewy,
I would say that the main advantages that you will get from EFI are driveability and economy when applied to a car that has a relatively high state of tune and spends most of its time being driven on the road. Choosing the right system is a bit of a minefield but some on here have done it succesfully and I think you would do well to glean from their experience. In your particular case I would say that apart from the economy a carb set up correctly will be more than adequate for racing.
As you know, my motor is putting out over 600bhp and is a relative pussycat to drive and this is all down to the EFI system being used.
Bluesatin is fitting EFI and Steve_d is also evaluating various componants and I would not be surprised to see more folk following suit.
I don't think that the factory are keen because the current recomendation is simple and it works (even though it could work an awfull lot better) and for some strange reason they do not seem to like change (or even market trends for that matter) but there will come a time when the market will dictate a change but who knows when that may be?
Anyhow, more and more folk seem to be putting their own spin on things regarding build spec these days and fuel injection is most definitely here to stay
and the more user friendly systems may become, the more appealing they will be to folk like us.
If you would like to learn as you go then Megasquirt looks like a very good option and from there the list is endless. It can be a costly project but very rewarding and more so for someone in your position as you are going from one to the other and will have a direct comparisson.
I would say that the main advantages that you will get from EFI are driveability and economy when applied to a car that has a relatively high state of tune and spends most of its time being driven on the road. Choosing the right system is a bit of a minefield but some on here have done it succesfully and I think you would do well to glean from their experience. In your particular case I would say that apart from the economy a carb set up correctly will be more than adequate for racing.
As you know, my motor is putting out over 600bhp and is a relative pussycat to drive and this is all down to the EFI system being used.
Bluesatin is fitting EFI and Steve_d is also evaluating various componants and I would not be surprised to see more folk following suit.
I don't think that the factory are keen because the current recomendation is simple and it works (even though it could work an awfull lot better) and for some strange reason they do not seem to like change (or even market trends for that matter) but there will come a time when the market will dictate a change but who knows when that may be?
Anyhow, more and more folk seem to be putting their own spin on things regarding build spec these days and fuel injection is most definitely here to stay
and the more user friendly systems may become, the more appealing they will be to folk like us. If you would like to learn as you go then Megasquirt looks like a very good option and from there the list is endless. It can be a costly project but very rewarding and more so for someone in your position as you are going from one to the other and will have a direct comparisson.
Hi Chewy, having been through the hole carb verses EFI thing i can tell you the difference is massive !!! economy is much better ,i would guess 25% on average on my road Can-am ,peak power is slightly down(could be sorted with a bit more mapping) but mid range torque is up by about 40lb/ft anywere from 2500 to 5000 ,engine ticks over and starts much better ,does not matter wether it is hot or cold !!! something i always had problems with !! engine has stopped using oil ???? don,t know why guess its down to bore washing ,reliability wise i don,t see why it should be any different than the carb system in fact i would go so far in saying the engine will be in a better condition running on the efi ,and if you look at how many MSD units have failed that speaks for itself !!! the other nice thing is you can plug in a laptop and see what everything is doing and tweek the map on the road as well .simon
Well, I'm going to defend the companys' decision to keep using carbs.
There is no doubt that EFI is the way to go, but having a carb is a very good starting point when building these cars. I would not have bought an Ultima if EFI had been the only option.
Probably something to do with my total lack of computer knowledge. It's all very well mapping it out on a laptop, but you need one to plug it into.
Also I don't have someone like Dawn who can sort the mess I would no doubt find myself in
There is no doubt that EFI is the way to go, but having a carb is a very good starting point when building these cars. I would not have bought an Ultima if EFI had been the only option.
Probably something to do with my total lack of computer knowledge. It's all very well mapping it out on a laptop, but you need one to plug it into.
Also I don't have someone like Dawn who can sort the mess I would no doubt find myself in
it is mate i wont tell anyone honest I would agree with all the sentiment above. You wont nessesarily get more power against a carb - flat out, but you gain the low/mid driveability - which may not appeal or be relevant in your case.
One thing that may appleal is fatures such as switchable fuel/ignition maps - you could have a slighlty leaner map and switch that in if you knew you were getting low on fuel.
I do think the factory should at least start thinking for efi, making tanks with high pressure pumps etc. Then the builder can decide which route to take.
One thing that may appleal is fatures such as switchable fuel/ignition maps - you could have a slighlty leaner map and switch that in if you knew you were getting low on fuel.
I do think the factory should at least start thinking for efi, making tanks with high pressure pumps etc. Then the builder can decide which route to take.
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