Choosing fuel injection method and throttle body sizes

[sonus]

So I am considering converting my Daimler 2.5 V8 to fuel injection.

I have three different methods that could be used;

1. Use the original inlet manifold and weld in injector bosses close to the head in each runners. Then replace the original SU carbs with two 1.75" throttle bodies.

2. Make a new inlet manifold with individual throttle bodies for each intake runner. Challenge is the small diameter of 28mm for the inlet in the heads requering either small bore TBs or a tapered inlet manifold

3. Make a new inlet manifold with a plenum and use a single larger TB.

Either way I'd require 200-220cc/min injectors, a trigger wheel, throttle position sensor and ECU to make it all run.

One of the reasons to change away from carbs is that the inlet manifold is a really poor design making the first and last cylinders of each bank run lean while the middle cylinders run rich due to fuel drop out and cylinder robbing due to some very convulted passages fromt he carbs to the heads.

Hopefully I can release a few extra BHP and make it a bit more fuel efficient and tractable.

Here's a pic of the engine

[reida1994]

I'd make a new manifold and fit the throttle bodies. When making the manifold, start by making and fitting the flange that meets the engine. Once the holes are in (slightly smaller than the ports. Weld the pipes, preferably metal with a decent thickness. Then make the flange for the TB's. Weld the flange on. Then grind the engine side to the same size as the ports, try to make it a bit rough. Finally, grind the TB side, make it bigger than the engine side and give it a slight taper. Make that rough also. Add the injector housing where ever is best for your vehicle. With regards to the TB's, you want longer trumpets. This gives more torque, especially low down.

[Copey]

2 banks of bike throttle bodies could work?

[Hillmanjames]

2 banks of bike bodies would be cool (which is a more than good enough reason to do it ) but would inherently have their own issues regarding balancing and initial setting up, but, once this has been sorted it would be a great sounding motor!

Seeing as your main interest is fuel economy, drivability and being generally a nicer motor, i would go the route of using a single throttle body and an decent sized shared plenum similar to the TVR manifolds on the rover v8 engines that they used. These just had 8 runners into a single plenum, fed by a single throttle body, simple

As you would also be using a standalone FI and ECU, you would not have the issues related to individual throttles such as getting a decent MAP source (MAF would be pointless), making sure they are balanced and the throttle position sensor works ok for all 8, along with the fact that tuning would be simpler with a single body.






single throttle bodies also make it easier when your piping up a turbo and the associated pipework


James

[RetroWarwicK]

how much room you got under the bonnet? i suspect a flat-ish plenum with a single TB would be ideal.

[sonus]

Not much room

The SU dash pot top hits the bonnet as is.

[v8ian]

Might be a good idea to give Russ Carpenter a call, he is a long time exponent of the Daimler V8, he can still claim to get 1500hp from his supercharged engine dragster, he hsd been playing with these engines for as long as I can remember. www.facebook.com/russcarpenterracing
or have a look here www.pistonheads.com/gassing/topic.asp?h=3&t=746237&mid=0&nmt=Old+Hemi+Daimler+V8++-+fuel+injection%3F

[welshpug]

something made like this would fit then.

[sonus]

Sept 18, 2014 20:37:48 GMT v8ian said:

Might be a good idea to give Russ Carpenter a call, he is a long time exponent of the Daimler V8, he can still claim to get 1500hp from his supercharged engine dragster, he hsd been playing with these engines for as long as I can remember. www.facebook.com/russcarpenterracing
or have a look here www.pistonheads.com/gassing/topic.asp?h=3&t=746237&mid=0&nmt=Old+Hemi+Daimler+V8++-+fuel+injection%3F

Russ built my engine 10 years ago
We've spoken about efi but I would like to see what other opinions there are about the subject

[sonus]

Sept 18, 2014 20:54:23 GMT welshpug said:

something made like this would fit then.

It might be too wide as my bonnet scoop isn't that wide.

[welshpug]

that's why I said "something like", that's off a ford V6, just used to illustrate tyhe type of inlet that could be made for it.