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Discussion Starter #1

Any of you guys ever considered using a set of these on an Alfa.
They're from a Suzuki GSXR motor bike and come in sizes between 38mm and 42mm.
The rubber mounts you see are apparently the same bolt pattern as Weber and they can be rotated to mount in any position. This should make them ideal for replacing the Alfa ones and mounting directly to the inlet manifold.

At only a couple of hundred dollars I reckon that they are a cheap alternate to some of the aftermarket Weber style throttle bodies.

I don't know much about what type of injector they use or if they are easily replaced with standard Bosch types.

My hotted up 2 liter currently runs a pair of 40mm Dells and it really needs upgrading to larger carbs or injection. If decided to go this way I'll be using a Megasquirt ECU, which I have left over from another project.
What do you guys think?
 

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Discussion Starter #2
What nobody interested?

Here's what they look like on an Alfa manifold.


46mm throttle plates with an outlet that tapers down to 40mm to match the Alfa's manifold.

Injectors are a bit on the small side but toyota denso types fit ok.
 

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Brett,

Awseome find!! I have been working on converting my Spica intake to EFI, coupled with a Halltech computer.

But $200 is much cheaper than my own conversion, and a lot less head aches.

How are you going to attache the throttle cable?

Also where did you purchase the manifold?

Thanks
 

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Discussion Starter #4
These particular TBs came of a 98/99 GSXR and I bought them on ebay for $100 US complete with TPS, injectors and fuel rail etc.

As it turned out they weren't the ideal ones for the alfa because I should have gone for the later model from 2000 on. According to a guy I was talking to in the U.K. these will bolt straight up to the alfas carby mounts as they have a spacing of 90mm between each body which is the same as weber carbs. However on an alfa the distance between 2 and 3 intake is 93mm but this don't matter too much because these TBs are mounted on rubber.

Mine had a spacing of only 80mm so I had to space them out to suit. I then machine up some adaptors from 20mm thick insulating block (sorta like bakelite) that I got from some redundant electrical busbars. The TBs were then bonded into these adaptors using Dow Corning 730 fuel resistant compound and pinned in place for good measure with four 4mm grub screws on each. I could have machined up some aluminium adaptors and mounted the TBs on their rubber mounts but I wanted to place the injectors as close to the inlet valves as I could get them.

I'm going to have to block off the radiator bypass connection below the thermostat coz the hose would come too close to the throttle mechanism for my liking.
So what do you guys think of doing away with this bypass altogether. I see it as only necessary for cold climates and here in Sydney Oz it doesn't get all that cold. Or am I barking up the wrong tree here altogether?

As far as the throttle cable goes, I'll have to search a wrecking yard for something suitable. I don't expect too many problems here.

For cold start idle control I'll be using an anti diesel solenoid from an old Ford to pop open the throttles a little. This works much better on individual TBs than trying to install some sort of IAC valve.

I've finished assembling the Megasquirt ECU and it's now on soak test until I get all the mechanical bits sorted out.
Then I'll be able to install the system in the car and then the real fun of getting it tuned up will begin.
 

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Looks like fun!! :D

What are you going to do for aircleaners, or velocity stacks?

Pete
 

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Brett,

Great info here.thanks for the detailed instructions. Now to hunt on E-bay....:D

As for the cold start, why not just hook up an old fashioned choke cable? I agree that IAC's are a pain cause they get old and dirty and make for a very uneven idle.

As far as the bypass, I have no clue.

Thanks again
 

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bcal said:

I'm going to have to block off the radiator bypass connection below the thermostat coz the hose would come too close to the throttle mechanism for my liking.
So what do you guys think of doing away with this bypass altogether. I see it as only necessary for cold climates and here in Sydney Oz it doesn't get all that cold. Or am I barking up the wrong tree here altogether?
The coolant bypass system is to allow coolant circulation thru the block when the thermostat is closed which prevents localized hot spots. However, pre-1750 engines with the screw-in stat had no bypass. I'd think it would be OK to run without the bypass but to be on the safe side, I'd drill a 3mm or so diameter hole in the flat portion of the stat flange to allow for a little coolant flow when the stat is closed. Actually, some stats have this hole when new for just that reason.
 

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For a system like this, what is wrong with using a SPICA intake manifold? You'll still need to machine the injector pockets and make a fuel rail, but the manifold is already set up for the Alfa motor.

I know Wes Ingram knows how to make the bores 45mm as well. You can find these manifolds VERY cheap on ebay.

Eric
 

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Eric,
Good point, but the Spica manifold will cost about $50, the injector pockets, mounts, clips, fuel rail, and pressure regulator, and injector connectors will run about $325, without injectors. So about $375 for the conversion minus any machine work, and injectors(would have to replace the Suzuki ones as well).

So the Suzuki manifold for $100 is a steal!!
 

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$325 is a little steep, as the hardest parts are making the fuel rail and machining the pockets. Neither of which are all that hard- I did both on our challege project- the Motronic manifold did not work with the injectors I could get.

I drilled out the injectors to fit with a drill press, just had to know the correct diameters. Then I brazed my own fuel rail together- should have soldered- it would have been easier.

Point is well taken, though. It is an all in one kit.

Still have to work out how to do the water bypass, throttle linkage, and the aiming of the injectors is far from ideal. The transient fuel calibration would be not fun.

Either way, its both a challenge and a VERY fun project.

Eric
 

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Eric,

I did forget that you do need a carby intake as well, if you dont have one, so tack on another 100-150, get a thermostat, etc, so now the price difference is not that great.
Maybe my stock Spica intake is the way to go, since I have it already.

Why would the injectors need to be re-aimed?
 

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Discussion Starter #15
Oops hit the post button instead of the preview.

Spicas are way too small at just 37mm. The inlet of mine are 47mm tapering down to 40mm. Throttle plates are 46mm. The later types have outlets of either 42 or 46mm with the latter being a bit too big.
My head has been ported ala Jim Kata........ less 1mm (I think he goes a bit too far for a road car) and I'll be using the standard 40mm intake manifold to promote good air velocities.

Injector angles are 30deg which is standard for most similar TBs.

I've seen the later types go for over $200 on ebay but I think they are sort after by the boy wonder bike racers. The earlier ones are a fair bit cheaper. Try this site instead of ebay
http://www.gdlcycles.com/asp1/findme.asp?qsmake=suzuki&qspart=throttle

If you were to use the later type you could mount them using Suzi's rubber mounts and this would then give better clearance between the throttle mech and the bypass hose. However you would also be moving the injectors further away from the valves which may result in flat spots. But then again it may not.
Another reason I mounted mine as close as I could was due to space limitations. There's only 8" clearance for the whole assembly. With the TBs fitted up I only have 4'' left for air cleaner etc. I'll probably use short stacks from a set of IDA48s if I can get them at the right price. I want to use one common air cleaner across all TBs. Any ideas?

Thanx for the advice on the bypass Papajam. I don't have a heater so I may use those outlets.

Those fancy TBs are way too dear for a tight wad like me. This entire EFI setup should cost me less than $700AUS including the ECU etc.
Here's a link to site for the ECU I'm using
http://www.bgsoflex.com/megasquirt.html

Yep this is sure fun alrighty.
 

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Kevin
If you look at one of the top pictures, you'll see that the injectors are actually aimed at the opposite side manifold wall. I've had to deal with this before (what I do for a living), and it can be a big PITA. Instead of the fuel hitting the valve, quickly evaportating, and then being inducted in when the valve opens, spraying on a cold wall does not force the fuel to evaporate. I can't say for certain that it will be a problem, but more that it might.

The 37mm is the taper at the end of the manifold. Wes Ingram tipped me off about that, it should, and can be, 40 mm at the junction. Plus Wes can tell you how to make the throttles 45 mm.

It still will be fun, no question about that.


Eric
 

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Eric,

FYI, regarding the injector aiming at the opposite manifold wall:

According to http://www.superbikes.co.za/content_gsxr1000.htm, Suzuki changed the Jnjector setup and added a "computer-operated secondary throttle butterfly valve [snip] to maintain ideal intake velocity".

It appears that this secondary butterfly also acts as a deflector that prevents the squirt from the injector to hit the opposite wall of the manifold wall, as can be seen on the picture copied below from http://www.superbikes.co.za/images/suzuki/GSXR1000_Injector.jpg

Now, this obviously requires more computer stuff to deal with...

Ruedi
 

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Sorry, here's an addendum to my previous message. According to a different text I found on the Internet (after I posted), the butterfly that gets hit by the spray is the primary butterfly, not the secondary.

A fairly detailed description of this throttle body and ECM, mentioning interesting stuff like the ECM having "eight fuel-injection control maps (one light-load map and one heavy-load map for each cylinder)" and controlling the "Suzuki Exhaust Tuning (SET) butterfly valve located in the pipe between the collector and the silencer" can be found at: http://www.globalsuzuki.com/motorcycle/moto/gsxr1000/pi_3.html.

BTW, Suzuki has also another throttle body (from the SV 1000s) where the injector is at 32º and the spray does not hit the primary valve -- but the 52 mm throat won't fit Alfas. See http://www.globalsuzuki.com/motorcycle/moto/sv1000s/pi_4.html for details about that one.

Ruedi
 

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Discussion Starter #19 (Edited)
Eric,
I agree with what you are saying there but it's not peculiar to these particular TBs because this problem exists with all EFI conversions on these old engines. Virtually every Weber pattern TB I've seen has the injectors mounted in a similar position and at the same angle. In actual fact the weber pattern makes things worse because it forces you to use the Alfa carb mounts which adds an extra 20mm to the intake length.
That's the main reason I went to all the trouble of fabricating those special mounts for mine.

The only way you could hope to hit the inlet valves would be to mount the injectors in the bend of an elbow facing directly down the runner. The TBs could them be mounted vertically thus creating a whole new load of clearance problems. Even so I did once consider this for a brief moment.

The ECU I'm using is, like most early injection systems, a batch type. That is it fires all injector simultaneously for every ignition event. This is unlike sequential EFI where the injectors are timed to individually fire at the most opportune time of a particular cylinders cycle ie: just before the inlet valve begins to open.
So my injectors will fire at least once every cycle when the inlet valve is closed and so squirting fuel directly onto the back of the valve at this stage is probably a waste. However injecting into the runner upstream and ensuring a good charge is available for the next cycle is probably beneficial.

Out of interest have you seen where Beninca Motors of Melbourne install their injectors?
http://www.beninca.com.au/erformanc_upgrades.htm
They mount them on the underside of the manifold so they fire directly up onto the roof of the inlet port. I considered doing this myself once and so I gave them a call to see how it worked. They weren't giving much away of course but they did say they were using a special type of injector. I imagine that they jet squirted rather than atomise sprayed the fuel onto the hot roof of the port where it was atomised and then sucked through the valve.

And that's probably the secret to success. Selecting the right injectors with a spray pattern to suit your application.

Thanx for forcing me to refocus my attention on this. Looks like I'll have a bit more investigation work to do.

Ruedi,
Thanx for that info. I can see from that pic of the later type TB what's going on. The ones I have are totally different. For example these injectors are at 45deg while mine are 30deg. The injector is totally different also. Looks it is designed to squirt the fuel as a jet onto the throttle plate. Mine miss the throttle plate altogether and spray as a fine mist. Pity they are too small. I also believe that they are peak hold which makes sense when you consider the rpms involved. Funny thing is tho, both types have a resistance over 12 ohms which is more like a saturated type.

The second plate is used to lower the differetial pressure (yes vacuum is pressure) across the throttle plate. This gives better control at lower rpms. I believe these bikes rev up near the 15 grand mark so there must be a fine line between providing air flow at the top end while maintaining good throttle control at the lower end.
The secondary plates are controlled by a stepper motor and i've read musing on yahoo about designing a circuit to adapt it to work on cars. Tho most bloke simply remove them and plug up the holes.

The more I learn the more I discover how little I knew.:confused:
 

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If you're aiming for performance at high revs rather then "around town" performance you should probably take into account that the injectors should be placed further away from the intake valve for best performance.
Check out the V6 intake runners on the above beninca link that have the injectors at the entrance of the stacks...
Also check out the pics from the pics from the Ferrari museum in the Pictures section, same setup.

Too bad individual throttlebodies are kind of a waste on a turbo car because they're really cool... :)
 
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