carburetor and TBI

[sachinpg]

we have decided to use Royal enfield 500 engine. But we saw Royal Enfield Classic 500 EFI is not available to us.

I just want to ask you can we buy a RE 500cc engine with carburetor and install throttle body injectors? in short we are trying to build our own EFI system for RE500 engine. Till now we have not done much work with any engine. Should we proceed with this plan? What you think is it possible to replace carburetor if RE500 with Throttle Body Injector? http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[sachinpg]

we have decided to use Royal enfield 500 engine. But we saw Royal Enfield Classic 500 EFI is not available to us.

I just want to ask you can we buy a RE 500cc engine with carburetor and install throttle body injectors? in short we are trying to build our own EFI system for RE500 engine. Till now we have not done much work with any engine. Should we proceed with this plan? What you think is it possible to replace carburetor if RE500 with Throttle Body Injector? http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[Jon Burford]

Yes it is possible of course.
Although be warned. Building an efi system is costly and requires much more work than a carb system.
If you believe it within the scope of the team to do it, You should do it. It will gain more design merit than a carb system.
In short you will need to consider the folowing
1. ECU - the most important part, this controls the fueling and firing on the engine
2. the injector
3. the fuel pump
4. the dyno rig - required to setup the engine
5. Crank cam sensing - you will need to attach a missing tooth trigger wheel to the engine and have a magnetic sensor connected to the ecu.

I imagine points 1 and 4 to be the most difficult. since they are expensive.
point 5 is the most technically demanding.

If you decide to go ahead I strongly recommend you talk to some manufactures of ECU's to determine what is best for you. I like DTA fast, they have great support, great pricing and the software is clever and easy to use.

good luck with it

[shark.ashwa]

It would be best if you stuck to the stock parts on your first go. Since you say you haven't done much work on the engine, I suggest you do that first. Keep the efi modification as side project, maybe you can use it on your next car.....it requires a considerable knowledge base. The most important things are getting your engine ready and running for testing in the car....

Regards,
Sharath

[sachinpg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">DTA fast </div></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">1. ECU - the most important part, this controls the fueling and firing on the engine
2. the injector
3. the fuel pump
4. the dyno rig - required to setup the engine
5. Crank cam sensing - you will need to attach a missing tooth trigger wheel to the engine and have a magnetic sensor connected to the ecu.

I imagine points 1 and 4 to be the most difficult. since they are expensive.
point 5 is the most technically demanding. </div></BLOCKQUOTE>
thanks

[sachinpg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Keep the efi modification as side project </div></BLOCKQUOTE>
sure first thing we are going to do is to get our engine ready with carburetor.
if we are going to change RE 500 carburetor to TBI, can you please suggest something??

[Jon Burford]

Yeah it really depends upon the strength and numbers of the team. and the availability of resources. I forgot to mention that you will also need an oxygen/lambda sensor for you exhaust.
There is a lot to consider. for example if you have access to a dyno or rolling road. you can use a rolling road although a full dyno is preferable.

Good luck with it

[Adambomb]

I wouldn't mess with TBI. By the time you've added the cost and complexity of EFI, it's a small step to get to MPFI. TBI would work better than a carb since it doesn't rely on a vacuum signal (which the restrictor does bad bad things to), but still has the following drawbacks:

1. All your fuel has to go through the restrictor
2. Manifold must be designed for wet flow. Puddling could negate a lot of the potential drivability benefits over a carb
3. What would you use for a throttle body?

I think there's a big reason there isn't much to offer on this scale, and that's because for the most part, TBI combines the the things that are bad about carbs with the things that are bad about EFI. They were common on passenger cars in the '80s-'90s, but IMO were sort of a kludge to get an engine otherwise designed for a carb to meet emissions and economy requirements.

[Kirk Feldkamp]

I was going to make the same comment, but I did a bit of googling and realized the Royal Enfield 500 is a single. I assumed they were going to put the injector in the port and not before the throttle like a TBI would imply. I think TBI was probably just a buzz-acronym word that popped up for him at some point and it stuck.

Sachinpg, the current "standard" injector placement for most basic performance applications is to shoot the injector stream(s) and the back of the intake valve(s). This helps vaporize the fuel, cool the valves, and does a good job of making sure the fuel ends up going into the cylinder and not just coating the walls of the intake tract. On very high performance applications, it's common to see two sets of injectors, often called a "high/low" injector setup. The "low" injector is often down by the valves like I described above, while the "high" injector is higher up near or above the end of the port runner. The idea is that during lower RPM operation the low injector does 100% of the work... but then as RPM's increase there is a transition (or split) to the high injector. At higher RPM's the fuel can actually mix and homogenize better when it's injected further up the tract, thus resulting is better and/or more consistent power production. In you case with that engine, you will probably just stick to just a single "low" injector. It will be easier to start, and I don't think that thing has a wide enough RPM range to warrant the added complication of a second injector.

[Jay Lawrence]

If you are going to use an air cooled engine, PLEASE duct it...

[Jon Burford]

Hi
Yes I misread.
I would not advise placing the fuel injector at the throttle body.
as Kirk said, a more standard practice is to have it pointing at the valves.
Whats the max rpm on the engine?

[Nicky]

@SachinPG: making an ECU for a single is simpler than that for a 4-cylinder. I know that the Gurus here would advise against this. I would strongly advise against this as most posts on this thread as you'd have other aspects that would require your time and resources.

Just for a reference we built an ECU for a single cylindered application for a lil over $100(sensors apart). This again was an exercise to develop competency in the team to understand and build a custom-ECUs. This also served as a topic for my Bachelor's Thesis. We however use the M800 on our event-going cars.

This is just a FYI and I strongly advise against attempting this as a first year team. This is one of the websites that I believe supports open-source ECUs. Wonder how many SAE teams use this. Nevertheless.
http://www.diyefi.org/

[sachinpg]

Thank you all for your suggestions, but we dropped the plan of TBI as we got RE classic500 engine with EFI.. I think now it is easier..

http://www.etalkindia.com/talk...ation-n-preview.html (http://www.etalkindia.com/talk/automobiles-review-road-tests/3187-royal-enfield-bullet-classic-c5-efi-bike-pictures-specification-n-preview.html)

by the way we successfully registered ourselves for FSG 2012...