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Throttle bodies

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Anyone ever fitted fuel injection throttle bodies like these to a 2.25 petrol engine?

https://store.jenvey.co.uk/throttle-bodies-and-components/throttle-bodies/heritage-dcoe/heritage-twin-tbody-40-48mm-pair-tdp40-48

Out of curiosity I was wondering what power gains could be got from this engine with porting the head, increasing compression and converting to mappable fuel and ignition systems.

Maybe a different cam for good measure....

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6 minutes ago, lo-fi said:

Not to a 2.25, but a mate has done so to an Essex V6. Works well enough. 

For a tinkered with 2.25, ACR have been doing that for a while:

https://www.automotivecomp.com/services/land-rover-products-and-services/

ACR are only down the road from me and I have seen some of the stuff they do although all their engines seem to stick with carbs. I have a mappable ECU on my Capri and have seen it done to many engines, just not to a Series one which got me thinking...

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I'm going to convey a 2.5 petrol to injection, but was thinking of just adding injectors to the existing manifolds.

Reason being, I think, is that the series motor needs lots of torque, but not massive high revs.

So the throttle bodies might not be necessary, as they're designed to increase the high rev flows. Or so I think, based off virtually no knowledge.

I'd planned on using ms, as that's not vendor specific, and so probably going to be supported as long as we have IC engines in common usage.

 

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18 hours ago, Bowie69 said:

Came across these recently:

https://vwspeedshop.com/product.php?productid=16854&cat=395&page=1

Solves a whole lot of problems all in one swoop.

That's really neat - I'm guessing numerous other units from small cars / large motorbikes could be adapted though.

Someone somewhere needs to get round to 'squirting a 4-pot, a few have started but not sure I've ever seen the finished product :(

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I'd start with the camshaft - which is ridiculously soft.  Very late 2.25 engines and the 2.5 use the diesel one which is a bit better and something more aggressive could well improve things still further.

next thing to look at could be to increase valve lift - different rockers - or offset the bearings.

 

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6 hours ago, FridgeFreezer said:

That's really neat - I'm guessing numerous other units from small cars / large motorbikes could be adapted though.

Someone somewhere needs to get round to 'squirting a 4-pot, a few have started but not sure I've ever seen the finished product :(

I'm sure you could use an old cast off, but this seems to tick every box, and is new, so less thinking 'I wonder if the throttle body is OK' when trying to diagnose a problem.

The other thing that occured to me with these in particular, is that they are pretty well sized for a 2.25, they do need a good squirting.

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What are the pros and cons with using a single throttle body, versus having 4 injectors in the manifold? Aside from the simplicity? 

I presume it is placed where the carb currently sits?

I'm more familiar with diesel, so think one injector per cylinder, so I'd like to learn if the single throttle body is easier, and the nature of the compromise, if any.

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Posted (edited)

Multi point injection has many advantages:

Fuel has very little chance to condense in the intake, so delivery is pretty much guaranteed to be even. 

Smaller injectors are much easier to modulate at low flow rates. 

Fuel is injected at an area where intake air speed should be highest, giving best atomisation and mixing. 

That being said, there's absolutely nothing wrong with single point injection on an old clunker like a 2.25. It's basically just an electronic carb replacement, so all you'd need is a small adaptor plate and you're in business.

My mate built himself a lovely Essex V6 for his 88 and made himself a custom manifold with a multi point setup. Unfortunately, he didn't pay much attention to the intake tract length and squished the plenum right into the V, giving very short runners. Now, if you don't know much about this, intake runner length is important and needs to be tuned against the cam duration and port size. On his setup, for best performance they should have been 24" long (look at the thor V8 setup). It ran, but anything under 4000 revs it would fart, pop and spit and generally not behave. Very little power too. In the end, after much discussion, we concluded that his 3" intake runners weren't getting any kind of momentum in the intake charger close the the valves (which stops flow reversals when the intake valve closes) and he decided to go for a carb manifold and the simple single point throttle body setup, rather than making a very elaborate multi point manifold. Happy to say, it works like a charm and now performs and behaves as it should. For an EFI setup on the 2.25, I'd look no further. And by the way: speeduino is a fraction of the cost of MS and perfectly adequate for this application - it's what he's using on his V6. It's pretty much a clone of MS - you even tune it with Tunerstudio - but on cheaper, generic hardware. 

 

Edited by lo-fi

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Precisely all the above :)Lots more wiring for multipoint too.

So essentially it is just a simpler, and very widely used system that is more than adequate for most DIY conversions that done already have multipoint manifolds available.

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So, unless I knew enough to get the distance from the injector to the valve right, I'm better off with single point?

Sounds good to me. 

Another dumb question, do/can the ms and speeduino systems take a crank position reading from the ring gear on the flywheel?

For some reason I'm not sure about the crank sensor being exposed at the front of the engine. 

If the ECU has a crank position, does it need a cam position sensor?

Sorry, going off topic.

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TBH the injector placement is not super critical on something like a Series, bear in mind you're upgrading from a clockwork thing :lol: so as long as nothing really bad is happening the fuel will find its way into the engine eventually.

You can't take crank position purely from a flywheel as you have to know where TDC is (you need an "index" mark, trigger wheels have a missing tooth or two) - but for fuel-only you don't need to know TDC, it's only ignition that needs to know which cylinder is firing / crank position - for fuel you just need RPM signal, often straight from the dizzy / coil -ve like wot flapper EFI does.

You don't need cam position at all.

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You could use a sensor in the dizzy (locked) to get cam position, and potentially (if my thinking is right) do away with the crank sensor entirely?

Crank sensor would of course be fine at the front of the engine, just put it up above the pulley out of the way.

audi do it another way (in days of old) they would get the crank speed from the ring gear teeth, the crank position from a timing pin on the fly wheel, and then use the dizzy to find out which piston was tdc about to fire.

could replicate that. Or you could machine the flywheel to have a 36-1 trigger pattern and use EDIS + wasted spark!

Wasted spark does away with the need to know which cylinder needs a spark, it will just fire both. On a 5 cylinder that is not advisable ;)

Many, many ways to skin this cat, all doable.

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It's the distance from the plenum to the valve my mate got wrong, but injectors on a multi point setup should ideally be placed at certain distances/angles. 

To get a simple setup working - as Fridge suggests - just take a feed from the dizzy cool connection to feed the ecu an rpm signal. If you want to do spark control too (this is where real power/efficiency gains are to be had), you can just lock the mechanical and vacuum advance mechs in the dizzy and use the points as a cam/crank position sensor with the ecu driving the coil. Bowie ninja'd me with this one, but we're on the same page :)

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There's plenty of universal trigger wheels out there that would bolt easily to a crank pulley, saves going in the bellhousing...

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ACR do a distributor less ignition system and heads, cams, exhausts etc are already available off the shelf so if that universal throttle body would do the  fuel job then it just needs that speedunio gizmo to control the fuel and ignition doesn’t it?

It seems then that all the bits are there to do the job.

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Absolutely. It would be quite a fun project. 

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10 hours ago, lo-fi said:

Absolutely. It would be quite a fun project. 

The Jenveys would make it cost prohibitive but with that single point throttle body it certainly becomes doable and probably something I will dig into a bit deeper as I’ve never heard of that speedunio gizmo before and presumably it’s just a mappable ECU?

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Speeduino or a lot of folks here run Megasquirt, which handles fuel and/or ignition.

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Individual injection throttle bodies seems like would make it drive like a PoS due to loss of fine control at tip-in (where the throttle is just opening). Would be a shame to destroy the engines best characteristic for no reason.

There was a guy in N. Hampshire (*) who made injector mount 'spacers' to fit between the standard manifold and head on his 2.25. Seemed to work pretty well, and it meant that playing with injector-valve  positioning was easy, just machine new mounts and swap them in. Could even use the standard carb as a throttle body to get things going.

I always liked the Bosch dual-plate throttle that VW used around the era of 16V GTIs. Like a staged carb, but one very small plate opening first and a second, larger than usual plate for wide throttle openings. Better control at tip-in, and less restriction at WOT than was sensibly possible with carbs.

(*) - this was more than 10 years ago, before I went to the dark and oily side and stopped messing with efi.

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Ah, this is a single point injection throttle body, so mounts on the manifold like a carb with a single injector. Saves having to faff about with mounting injectors in a manifold not set up for it. Agreed individual are the opposite of what you want in a Land Rover! 

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I’m unfamiliar with the speedunio thingy but I have an Emerald K6 in my Cosworth Capri and Emerald say it will quite happily run a 2.25 petrol engine with that single point throttle body and a coil pack. Definitely on the list of things to do when the restoration starts.

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Posted (edited)
53 minutes ago, lo-fi said:

Ah, this is a single point injection throttle body, so mounts on the manifold like a carb with a single injector. Saves having to faff about with mounting injectors in a manifold not set up for it. Agreed individual are the opposite of what you want in a Land Rover! 

Out of curiosity, injectors upstream or downstream of the throttle plate? I presume upstream but I can't tell from a brief look at the website.

I did TPI on a 3.1L Essex a *very* long time ago. It works well, the engine made probably a little more power, but the driveability was transformed compared to running on carbs. With EDIS6 it was even better again. I used the Chevy TBI as at the time it was the only way to find parts large enough to feed a hungry V6 from only 2 injectors. (Running on carbs it was basically undriveable off-road, as some members of this forum will remember!)

PSA used the Bosch TBI on midrange 1.4 and 1.6 engines for a few years. These would have been engines making making a little less than 100hp, and with smaller capacity but higher revs than a typical series, I always thought that could be a very simple setup. Possibly only need mods to the intake manifold to mount the TBI where the carb was. They are also wide and squat, designed to be used downdraught. The injectors were an oddity though in the ones I've seen, much more like the chevy shape and style (possibly even the same), rather than the typical mpi injector most people are used to.

 

Edited by TSD

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Apologies, I lost track of where the original post started from as we'd been talking TBI with the 'universal' jobbies Bowie posted at VWSpeedshop most lately. Understand your comment about individual throttle bodies with reference to the Jenvey ones now! 

The universal TB looks like it's got the injector downstream of the throttle plate, but agreed its hard to tell for sure. 

41 minutes ago, TSD said:

I always thought that could be a very simple setup. Possibly only need mods to the intake manifold to mount the TBI where the carb was

Exactly what Tom did on his Essex V6 controlled by Speeduino. I'll ask him what TB he's running. 

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