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Location: qld
Registered: May 2003
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positives of fuel injection over carbs
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Fri, 19 December 2003 13:31
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hey i am think of converting to fuel enjectio for my 2tg i have the twin side draft solex on them now im just wondering if i could get some more opinouns.
i know you get better fuel economy and more power but how much more power is there to gain, am i wasting my time and money converting.
Jason
thanks all
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Location: Kita-Ku, Sapporo, Japan
Registered: January 2003
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Re: positives of fuel injection over carbs
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Fri, 19 December 2003 14:05

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it all depends on how badly your carbs are working.
seems that maximum power from a well sorted carb setup (ie extensively dyno tuned) will be similar to that from an EFI setup.
however, most ppls carbs are not well tuned, and even then, carbs are a bit of a compromise as they are trying to supply fuel from idle all the way to WOT redline in the same package.
carbs work pretty well, but with programmable EFI, you can get the mixtures spot on, throughout the rpm and load range, and for different transient conditions.
apart from complexity, a well sorted EFI system will always be marginally better (at least) than a well sorted carb setup.
anyhoo, thats my ideas...
Cya, Stewart
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Location: Brisbane / Gold Coast
Registered: May 2002
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Re: positives of fuel injection over carbs
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Fri, 19 December 2003 14:05

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Positives - Everything, except for ...
Negatives - It costs more.
If you can cover the cost, there is no way you'd use carbies again with a decent engine management system.
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Location: Melbourne
Registered: October 2003
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Re: positives of fuel injection over carbs
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Fri, 19 December 2003 20:31

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as for power the Carbs are cabable of getting more power out of the engine Jason. Pretty much coz they can force it to do what you want. Depending on the CR of the pistons aswell. About 90% (methinks) of 2TGEU were 8.5:1 where as the 2TG had 9.8:1. And according to the stock specs from Toyota the power figures are as follows
2TG - 124hp@6400rpm (92.5kw)
2TGEu - 113hp@6000rpm (84.2kw)
But the carbies are apparently notorious for going out of tune so that was number one reason why I didn't go that path. and the ease of the efi...'plug n play'
Hope I've helped, btw I'd like some more details on that manifold you said you were going to buy if you could get it thanks.
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Location: brisbane
Registered: October 2003
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Re: positives of fuel injection over carbs
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Fri, 19 December 2003 22:10

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jason & T APLUS 22 ....email sent
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Location: Brisbane / Gold Coast
Registered: May 2002
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Re: positives of fuel injection over carbs
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Sun, 21 December 2003 10:09

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T APLUS 22 wrote on Sat, 20 December 2003 07:31 | as for power the Carbs are cabable of getting more power out of the engine Jason.
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No way. The only way that could happen is if the EFI gear wasn't properly tuned.
A well tuned EFI engine will make more power, run smoother, and use less fuel than a carby engine will at all revs.
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Location: Adelaide
Registered: May 2002
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Re: positives of fuel injection over carbs
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Sun, 21 December 2003 11:19

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Performance will depend wholly on your inlet system. EG, Are you planning to run a factory injection type plenum and throttle body?
For example, While a conventional (eg factory style) plenum with a single throttle will probably drive better all round while being more fuel efficient, The restriction in the system will be greater than that of a pair of good side draught carbies.
The carbies on the other hand would pose offer less restriction which is great for power, however would not behave as well. Also would drop a bit of torque methinks.
A good option would be a well designed custom plenum which flows well and is designed for your desired torque/engine characteristics. Then finished with a largish (not too huge) throttle and garnished with good aftermarket EFI. It would be smooth providing the tuning was done well, offer decent power and economical too. (ALL DEPENDANT ON TUNING!)
My ultimate setup, would be... You guessed it!, A set of quad throttles with EFI. Would give you the best of both worlds and pose even less restriction than the Carbs. Sure it might cost a bit to innitially setup but you could always take them with you to your next car. Not to mention the sound, Ohh the marvellous sound it would make
The would even make a good basis/addition to a well angry 2TG.
If your handy with your metalwork it wouldnt be too hard to, say, adapt a set of webbers to quad throttle duties (looking at you bill ). Or try adapting 20V throttles, bike throttles etc
Would make a great tech article
Rex
[Updated on: Sun, 21 December 2003 11:30]
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Location: Melbourne
Registered: August 2003
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Location: Brisbane
Registered: May 2002
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Re: positives of fuel injection over carbs
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Sun, 21 December 2003 13:30

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Yes, DCOE pattern throttle bodies are common and widely available, but they're far from cheap. Totally worth it though if you can afford it. 
As for the factory 2T-GEU manifold and plenum, I think you'd have to build a pretty full-on engine before it became too much of a restriction. For a mild street engine it will perform just fine, and when cost is factored in it's a pretty good option IMO.
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Location: Brisbane / Gold Coast
Registered: May 2002
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Re: positives of fuel injection over carbs
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Sun, 21 December 2003 21:02

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Yeah, I should have made that more clear - Yes, a pair of Webers will make more power than the stock EFI inlet system on something like a 4AGE, which has a plenum and poor runners.
A 2TG is pretty good with the carby system, though if swapped over to EFI throttle bodies it'll still make more power.
For cheaper & better throttle bodies, try Alloy Race Components in Melbourne.
Here's a pic of a set I have to go onto an engine.

The blocks are 20mm thick, so you're not stuck with the typical DCOE clone-type throttle body, which are almost always too long for the right length inlet system.
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I supported Toymods
Location: melbourne.victoria.austra...
Registered: June 2002
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Re: positives of fuel injection over carbs
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Sun, 21 December 2003 21:08

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ooh i've seen them before bill 
carbies vs fuel injection - depends on what you want your car for - ultimately for drivabilty ect - EFi cannot be beat - cold starts warm starts and driving street - its great.
track work and race meets, i might sway towards a properly setup/balanced/tuned set of webers.
both are just as expensive as each other these days.
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Location: Brisbane / Gold Coast
Registered: May 2002
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Re: positives of fuel injection over carbs
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Mon, 22 December 2003 11:55

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Grega wrote on Mon, 22 December 2003 08:08 | track work and race meets, i might sway towards a properly setup/balanced/tuned set of webers.
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Nope, still definitely not as good as EFI. EFI will compensate for temperature variations of water, air, etc, altitiude, and so on so the mixture is right all the time.
A carby won't do any of that.
The Webers on my 1300 racer are as good as we or anyone else can get them, yet they still run too rich in the mid-range and my corner exit speed is not as good as it should be at times. With EFI, it would be perfect all the time.
You are also limited as to the minimum total length of inlet manifold with carbies, with EFI you can have them much shorter if need be.
(On my new 4AFE, the inlet will be less than 5" long)
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I supported Toymods
Location: melbourne.victoria.austra...
Registered: June 2002
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Re: positives of fuel injection over carbs
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Mon, 22 December 2003 19:05

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good point you make there bill...(re: altitude/temp compensation)
and agree. if your carb(s) sit at the end of a manifold the fuel has the chance to puddle/clog in the inlet manifold, with EFI (namely port fuel injection here) the injector sprays the fuel into the back of the inlet valve, with only air travelling down the inlet runners.
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Location: Brisbane / Gold Coast
Registered: May 2002
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Re: positives of fuel injection over carbs
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Tue, 23 December 2003 11:01

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Sort of! 
The new engine I'm building (www.billzilla.org/starleteng.htm) will have eight injectors, four in the head close to the valves and another four out in the end of the trumpets.
When you have a bit of throttle & revs up, it's better to have the injectors out in mid-air as the atomisation helps make the air a bit cooler.
There should be about 3% - 4% more torque if I do it that way.
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I supported Toymods
Location: melbourne.victoria.austra...
Registered: June 2002
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Re: positives of fuel injection over carbs
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Tue, 23 December 2003 19:14

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interesting bill, i remember seeing an XF in mag with the injectors positioned like that - indeed will help with atomisation of the fuel - the cooling of the air though is an interesting point!
gotta go see john and get some of those nevo pulleys. yum
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Location: Brisbane / Gold Coast
Registered: May 2002
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Re: positives of fuel injection over carbs
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Tue, 23 December 2003 20:04

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Yep, that's where I got the info from. I also emailed the guy and got the answers I was after.
Also also forgot to mention that with the Webers on the racer, we had to put 'top hats' on the round covers on the top of the carby body, and extensions on the air correction jets to stop them flooding when cornering hard.
They run okay, but nothing like EFI ...
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I supported Toymods
Location: melbourne.victoria.austra...
Registered: June 2002
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Re: positives of fuel injection over carbs
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Tue, 23 December 2003 21:06
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so for the benefit of ta2272 - go EFI.
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