Twin or Quad throttle body fuel injection

Can anyone here fitting fuel injection tell me if Twin or Quad throttle body injection would work on a VW engine. I'm thinking of trying to develop a Quad set-up using the throttle bodies off a Corolla.

Adam.....

I had quad throttle body injection on my 1916 engine in my Manx...went very well...but the induction noise got the better of me so it now has a Subaru...

What throttle bodies did you use. The corolla ones are all that I have found so far and cost around $200 with manifold and injectors although I have to cut the manifold in half and re-tap the fuel inlet for another fuel feed pipe.

Have u got any pics of the Corrolla T'body ??

Your better off using a single throttle body they work better

using quads is a pain as you will spend more time adjusting and syncronising them

everyone i know who had twins or quads has gone back to a single set up even the guys with the quick drag VWs

57 Panel wrote:What throttle bodies did you use. The corolla ones are all that I have found so far and cost around $200 with manifold and injectors although I have to cut the manifold in half and re-tap the fuel inlet for another fuel feed pipe.

Redline Webber.

vw54 wrote:everyone i know who had twins or quads has gone back to a single set up even the guys with the quick drag VWs

were they running turbo's or N/A setups ?

A single throttle body will kill air flow on a N/A vw because of the manifold.

Boosed engine will loose flow too but it can be made up for with boost.
Most boosted engines have restrictive tubes between the turbo and engine either way so it will be less obvious.

that's what I thought..............my understanding is that twin throttle bodies would be better, although I have never run fuel injection, I would have thought the principles would be similiar as carbies.

Here's a picture of the throttle bodies off a 20v Totota Corolle engine.

I've found a set for $150 including throttle position Sensor. From the picture it looks like if I cut the manifold in half I can tap the open holes to take another feed pipe.

I ran a single with plenum, and went up to quad and the improvement was as expected, but certainly more induction noise.👍

I have quad throttles and they work great. They are off a K100 BMW m/cycle

I've also started looking at Honda 954 and Yamaha R1. What computer are you running. I only want a symple one. Most newer computers are too over the top for what I need.

were they running turbo's or N/A setups ?

they have all been Turbo
no reduction in HP in most cases a increase


theres lots of heating / cooling tube on that honda set up keep it simple is the object of the game

have a look at my set up

http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099

Here are the R1 TB's. It looks like they can be split into pairs.

looks like it what about the fuel rail

I run a Gotech ECU (www.gotech.co.za) which is the cheapest around at about $400. It does everything I want spark, tps input, closed loop, logging direct fire etc. Howver I have sung its praises in the past on this forum and just copped flack for pushing it.

Mortgage your house and buy a Motec, Haltec or Wolf - I'll stick with my Gotech the whole system including injectors, throttle bodies, fuel pump, fuel rail and other sensors cost me about a grand all up.

My engine is NA but it can handle a boosted engine.

Ken

Thanks Ken. That would do all I need. It's not as if I need an ECU that can handle 50 different inputs.

which model gotech are you using Ken?

GOD DAMN - just finished typing a response and lost the lot 😠

Try again,

Horses for courses.

For performance applications ITB (individual throttle bodies) are the way to go. That's why manufacturers like BMW only use ITB on their M-Power vehicles. Also why motocycles (light and rev to over 10,000 rpm) use them. What's interesting with the BMW M5 is that even though it uses ITB, it also has a plenum from which manifold pressure readings are taken.

On the other hand, for a daily driven application the single TB and plenum are able to be properly tuned using throttle opening (%) and load (MAP). You only have throttle opening on a ITB system. That's why 99.9% of vehicle manufactures use single TB and plenums.

The other issue with ITB on a VW engine is the linkage. When the engine is cold and the TBs are all shut, how far will they open when the engine warms up?

Just the basic one Gotech MFI

With my ITB's I just run a TPS sensor and it runs like a dream - idles at 650 rpm and revs out with no flat spots or hesitation. Starts first pop with no cold start set up and warms up very quickly.

So your system has the same ignition advance at say 2500 rpm at 30% throttle, regardless of whether its cruising or climbing a hill?

Yes - that's correct. That would be true if you had a map sensor - at 25% throttle and a set RPM the manifold vaccum would be the same whether you are cruising or climbing a hill.

It is well recognised that MAP-based tuning is a more accurate method of determining engine load. That's why all manufactures use it.

How does a TPS-based system differentiate between a free reving engine at 100% throttle opening and an engine under load (climbing a hill) at 100% throttle opening?

I'm not saying your set-up doesn't work, it probably works well. But there are better ways. The modern ECU can generally compensate for poorly designed systems.

Sorry but you need to think about it a little more.

The reason MAP based systems are used is to more precisely control fuelling during transient driving for emission control reason. eg over run cut etc. But for performance on a NA engine a TPS system is just fine. If it is a boosted engine then by definition you need to measure manifold pressure.

If you had 100% no load the engine would not be rev limited and self destruct. The only thing that controls the RPM at 100% throttle is the load applied. If you have no load and want to control the speed to say even 6500rpm you would close the throttle.

In either case a TPS shows 100% throttle and a MAP sensor would show zero vacuum.

Trust me for every day driving when you are not too worried about meeting emission a TPS system works perfectly fine and much better than a MAP based system with ITB"s. Most ecus can be set up for 100% TPS.

Ken

Judsons4eva wrote:The reason MAP based systems are used is to more precisely control fuelling during transient driving for emission control reason.

Thank you. You are now arguing for my side!

Judsons4eva wrote:for performance on a NA engine a TPS system is just fine.

That's what I said. It's fine but there are better systems.

Judsons4eva wrote:If you had 100% no load the engine would not be rev limited and self destruct. The only thing that controls the RPM at 100% throttle is the load applied. If you have no load and want to control the speed to say even 6500rpm you would close the throttle.

No. You are missing my point. It's about ignition advance and what the engine wants at certain LOADS. A TPS does not accurately tell the ECU the LOAD the engine is experiencing.

56astro wrote:The other issue with ITB on a VW engine is the linkage. When the engine is cold and the TBs are all shut, how far will they open when the engine warms up?

The ITB's are not shut when the engine is cold.....they are open to a pre determined gap so the engine will run.The linkage is adjusted while the engine is hot.The linkage is "longer" than required when the engine is cold as the intake manifolds are not spread as far apart until the engine heats up. I had no problems with mine at all. It ran a TPS and MAP.Air flow meters suck.

As I said trust me - I am a professional automotive r and d engineer with 30 years experience and hold patents in fuel injection. If the system is mapped correctly on a dyno and everything is kept in adjustment (no likage wear etc) you see no difference in ignition advance between TPS and MAP. A number of production EFI motorcycles use just a TPS and no Map sensor.

The TPS does reflect exactly what load is on the engine. For a given throttle position and the a given load the only variable is the speed (rpm). So the power being produced is a function of TPS and RPM. If you change the load the speed changes, if you change the throttle load changes and speed changes.

The only benefit of MAP is handling transient condition and a well mapped TPS with correct enrichment settings will handle that. Spark is not really an issue.

I have ITB's so TPS in much better. If you run a single TB then go with MAP.

Ken

My TB's have individual air bypass needle valves (idle valves) so at idle the throttles are shut so linkage movement is not an issue. The other (and more complicated way) is to set up an idle control valve.

It looks like I'd have to modify the fuel rail.

Schematic of an EFI system for a motor scooter. I think this is a Vespa. TPS only but with an idle air control valve

Why do you keep comparing motocycle engines with a VW motor. Any faults in the system caused by poor tunabilty can be overcome due to the extremely light weight.

But anyway, what is the sensor No. 7 ??

MickH wrote:

56astro wrote:The other issue with ITB on a VW engine is the linkage. When the engine is cold and the TBs are all shut, how far will they open when the engine warms up?

The ITB's are not shut when the engine is cold.....they are open to a pre determined gap so the engine will run.The linkage is adjusted while the engine is hot.The linkage is "longer" than required when the engine is cold as the intake manifolds are not spread as far apart until the engine heats up. I had no problems with mine at all. It ran a TPS and MAP.Air flow meters suck.

Yes Mick, as I said, modern ECUs are able to compensate (to a certain extent) for poorly designed systems.

On your particular system, is 0% throttle recognised by the ECU when the engine is cold, hot, or never ?

As Ken said, the proper way to overcome cold running is an Idle Air Control Valve.

56astro wrote:Yes Mick, as I said, modern ECUs are able to compensate (to a certain extent) for poorly designed systems.

On your particular system, is 0% throttle recognised by the ECU when the engine is cold, hot, or never ?

As Ken said, the proper way to overcome cold running is an Idle Air Control Valve.

Yes...why wouldn't 0% be recognised???? That's like asking would WOT be recognised. Isn't this getting a bit offtrack anyway from the original post?? It's turning into a "mine is bigger than yours" discussion.👎😘

56astro wrote:Why do you keep comparing motocycle engines with a VW motor. Any faults in the system caused by poor tunabilty can be overcome due to the extremely light weight.

But anyway, what is the sensor No. 7 ??

Astro - I am afraid your out of your depth mate, for an EFI scooter to meet Euro 4 emissions its control needs to be better than any aircooled VW on the streets today. The small displacement means pulse width precision needs to extremely good as does transient control.

I was waiting for yr question on sensor 7. If you look carefully at the diagram you will see that the pressure sensor is upstream of the throttle blade and therefore is not measuring manifold vacuum but just atmospheric pressure. To measure manifold pressure the sensor must actually measure pressure in the intake between the throttle and the intake valve,

If you want use your MAP sensor go right ahead but other readers of this forum hopefully will accept that based on common EFI practice 100% TPS is a viable tuning method particularly with multiple throttle bodies and all good aftermarket ECU's MOTEC, Haltec, Wolf, Gotech have the option of this mode.


Ken

What inputs are needed, by that I mean the minimum to run an EFI engine. And I found another picture of an R1 throttle body that shows the fuel rail. I'm sure you could make, modify or get one to fit when the two halves are split

Speed (signal from disi with hall effect sensor), throttle postion, engine temp, air temp.

That's it

Those TB's look fine - split them and block off the fuel rail and it will work.

So we'll be seeing that type of system on all the european cars as well then??

MickH wrote:

56astro wrote:Yes Mick, as I said, modern ECUs are able to compensate (to a certain extent) for poorly designed systems.

On your particular system, is 0% throttle recognised by the ECU when the engine is cold, hot, or never ?

As Ken said, the proper way to overcome cold running is an Idle Air Control Valve.

Yes...why wouldn't 0% be recognised???? That's like asking would WOT be recognised. Isn't this getting a bit offtrack anyway from the original post?? It's turning into a "mine is bigger than yours" discussion.👎😘

Mick, you said in your post that the linkage is adjusted while the engine is hot.
Is that when the ECU recognises 0% throttle? Or more? Or less?
Or is it when the engine is cold when the linkage iis "longer" than required.

If the engine and linkage does grow, at what point does the TB read 0%

56astro wrote:The other issue with ITB on a VW engine is the linkage. When the engine is cold and the TBs are all shut, how far will they open when the engine warms up?

This problem only occurs with the Kadron style linkage, not weber/dellorto linkages which are the type you use with ITB setups. Heat, or the 'growing' of the engine does not affect the carb sync on weber setups, so carby sync is maintained hot or cold.

56astro wrote:So we'll be seeing that type of system on all the european cars as well then??

Geez Astro - you just don't get it do you. This thread is about the merits of twin or quad throttle bodies. Clearly TPS is a viable solution on engines with an unreliable or fluctuating vacuum signal. That is - quad throttles or single cylinder m/cycle engines. Yes more modern multi cylinder engines use a MAP sensor - but the use of MAP sensors on modern cars as the primary input sensor went out 10 years ago at least. These systems are called speed density and no modern car uses speed density systems in production. It is viable as cheap aftermarket conversion for carbis - just as a TPS system is. Today ALL modern cars use a MAF - (mass air flow sensor). So the little knowledge that you are trying to demonstrate on this thread is getting in the way of sound advice to keen VW tuners wanting have a cost effective and reliable EFI system.

Ken

😀😀😀
Good one Ken

Adam - back on topic

Here is a basic wiring diagram for good cost effective system.

From the www.gotech.co.za website.

Ken

This is the type of info I'm after.

Adam.....

Judsons4eva wrote:Adam - back on topic

Here is a basic wiring diagram for good cost effective system.

From the www.gotech.co.za website.

Ken

Out of interest Ken what are your thoughts on megasquirt?

Also what manifolds have you used with your k100 throttle bodies?

thanks

kkk

koolkarmakombi wrote:

Judsons4eva wrote:Adam - back on topic

Here is a basic wiring diagram for good cost effective system.

From the www.gotech.co.za website.

Ken

Out of interest Ken what are your thoughts on megasquirt?

Also what manifolds have you used with your k100 throttle bodies?

thanks

kkk

A quick read of the manual indicate the megasquirt looks very difficult to set up. If you immerse yourself in it and understand all the various terms you not only learn a lot about engines and engine tuning but also end up with a good system.

On the other hand most of the latest series of aftermarket ecu's Motec, wolf, etc have much easier to set up windows based interfaces. For example after setting up the basic parameters in the Gotech you just adjust the height of a bar on a bar chart to vary the fuelling rate or ignition advance.

I used stock type 4 EFI manifolds with a cast iron base, cut the 4 runners tubes off and machined them to accept the base of the 4 K100 TB's. Just by chance the spacing of the K100 TB was exactly the same as the spacing of the manifold ends so the BMW linkages also were useable.

Ken

Hey Judsons4eva, that set-up looks REALLY good!!!
After reading you posts, I might switch my MegaSquirt II over to TPS based, and compare the two modes.

I think the MSII is easier than it looks, though you DO need to read the manual, and do your research! But it has a lot of features that we probably don't need. Also, the software is windows based, and apparently will even run on Vista, if that's your thing.

I've decided that the R1 throttle bodies are too complex and I'm now looking at CBR 954 RR instead. The new problem I have thought of is what's the best material to make the inlet manifold out of. Aluminium seems the popular choice from an OEM so is it the best or could one be made of SS. Would the thermal expansion rate difference cause any problems.

Adam.....

The expansion rate of the manifold material shouldn't make any real difference. In theory stainless would give some advantage as it would not retain much heat to transfer to the intake aire. However the most important thing is to get a smooth air flow from the throttle body down the the cylinder head/manifold interface with well matched ports.

Ken