EFI conversion, a crossroads, which way to go?

[sprint95m]

I am gathering the parts to convert an 1850 to EFI.

To this end I bought a TR7 EFI inlet manifold but have found a snag....
whilst the manifold fits the cylinder head, it does not have a wide enough flange (for ports 3 and 4) to cover the coolant transfer slot.
(1850HL and TR7 heads don't have this CTS).

I have different options, including
1. trying to block the CTS
2. fit an 1850HL head
3. fit a 2 litre engine. If I do this I will go Sprint I feel.


(I have a suitable gearbox and prop for a Sprint conversion.)


As always, thoughts and opinions are most welcome,



thanks,


Ian.

[Jon Tilson]

I'd fit the later TR7 1850HL head to your block.

That way you can be sure of the gasket quality, make sure the studs and bolts are good and take advantage of the bigger
valves.

Its also possibly the cheapest option on the way to greatness...

Failing that a TR7 engine but with 1850 fittings, but the OE axle will be marginal.

The EFI manifold wont fit a Sprint.

Jonners

[Carledo]

You beat me to it Jonners but my advice matches yours. Though I think, on balance I would prefer the extra ccs of the TR7 block as well as the head. And with the extra power involved, a Sprint axle would be nice. I reckon a carefully built, injected 2.0 8v should rival a Sprint in power output and be much more economical as well. The 3.45 axle will help with this as well.

Steve

[trackerjack]

You intrigue me Steve. Why would economy be better as I thought 16 valve layouts were able to burn leaner mixtures better than 8 valve ones. Please educate me.

[Carledo]

You intrigue me Steve. Why would economy be better as I thought 16 valve layouts were able to burn leaner mixtures better than 8 valve ones. Please educate me.

I think the economy will come from the EFi rather than any putative gains from differences in engine design. The 8v Carlton lump in my car with EFi and managed ignition gives me a pretty consistent 36mpg average. That's with the fuel pressure set at the stock 2.7bar which I run all the time except when racing. And it does NOT have an easy life! On the mostly rural and camera free Shropshire roads it gets opened up whenever the opportunity presents itself - which is RATHER often! A 16v Sprint on carbs, used in a similar fashion would struggle to average 25mpg.

TBH, I am still in 2 minds about 16v technology. It MUST be better or manufacturers wouldn't use it so much (unless they ONLY do it for the lean burn properties, to meet emission and MPG targets) but to me, it seems a complex solution to a simple problem and doubling the weight and moving parts in the valve train must have a price in frictional and rotating weight losses. Not to mention the added manufacturing and maintainence costs.
But what do I know? I'm only an an ancient and (very) empirical engineer.

Steve

[zombeh]

The massive advantage of more smaller valves is that you can fit a lot more valve circumference to get the air in and out through into the same bore size. Also, putting the valves where you want them in a 2 valve head gives you a lot of the issues of a 4 valve one without all of the advantages and further limits you on size.

Flat out there's not going to be a lot in it between well set up carbs and injection, the difference is in how well you can set them up for as much of the engine's operating window as possible without compromising the important areas too much. Economy will come from a bit more precision and better atomisation in the part throttle cruise parts of the map, being completely cutting the fuel on overrun and above all having precise control over the ignition. Oh and most importantly for me being able to adjust them in the warm and the dry rather than getting cold and wet and burning your fingers.

It'd be interesting to see how much you could get out of a 2 litre 8v in the sprint subframe giving you room to fit a proper exhaust in there. If it were me I'd sprint it, but then lots of people have done that.

[soe8m]

I know for sure that an 1850 std cam efi on lpg can have 105 at the wheels, about std sprint figures.

Jeroen

[sprint95m]

Thanks for your input everyone.

I am trying to get an 1850HL head.

To get an idea of what is involved I have been looking at the EFI injection manifold in situ.
I have concluded that a TR7 radiator must sit lower relative to the engine than a Dolomite, the hoses are going
to take a bit of thought. Not that it is a problem, I will have to vent the radiator directly to the header tank.
For the thermostat housing I will use a T2000/Spitfire type.

A lot of radiators have top and bottom spouts on the same side. Using a TR7 thermostat housing it would be possible
to use one of these for a EFI slant four 8 valve, however,
I am going to stick with the Saab radiator I already have in use.

thanks,
Ian.

[soe8m]

I do have a thermostat cover with a bend and filler from my setup if you like. A dolomite you top up on the thermostat cover and a tr7 on the cooler or tank so I had no opening to fill. I do not use this anymore because it is going to be "sprinted".

Jeroen

[sprint95m]

Thanks for the offer Jeroen.

I already have a remote header tank (Volvo 850) so filling up the system is easy and,
I think I already have the bits to connect up the inlet manifold satisfactorily.



thanks,

Ian.

[Galileo]

In the classic I saw this and thought of you way, I er, saw this and thought of you! It's a no damage EFI conversion using the standard carb (Stromberg or SU) as a throttle body. American, but I won't hold it against them!

CarbsNeedInjector.jpg (84.1 KiB) Viewed 1752 times

[Mahesh]

Looks interesting, would like to speak to a Sprint owner who has.

[sprint95m]

Thanks, I have already looked at they carburrettor conversion adapters.

The biggest limitation with them is that you are still using the original inlet manifold,
ideally you want a separate runner for each cylinder, made as straight and as long as possible.

Whilst an 1850 manifold isn't bad, the TR7 EFI design is much better.




Ian.

[Galileo]

I see that, you do ideally need a manifold with a long runner for a good usable torque response at low to mid revs, unless you're building yourself a race engine that will be sat at high revs most of the time. And of course there would still be just one injector for each pair of cylinders. I guess if you was trying to keep your car as original as possible it's a great idea, otherwise maybe not so.

Take an old manifold down to Bogg Brothers with a fistful of cash and tell them to get cracking!

[sprint95m]

Take an old manifold down to Bogg Brothers with a fistful of cash and tell them to get cracking!

That will work or you could make your own......
http://sideways-technologies.co.uk/foru ... brication/






Ian.