Individual Throttle Bodies

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Hjulen

Individual Throttle Bodies

Post by Hjulen »

Has anyone ever thought about doing ITBs on a spider other than for racing applications? There are a few places that sell throttle bodies that fit onto a stock IDF or DCOE manifold(of which there are plenty for our motors) however they are expensive, between 600-700$ for a set.

The other option is to use motorcycle throttle bodies and adapt them to fit a FI manifold with the plenum chamber flange cut off as can be done with some other cars. Maybe even gut some IDFs use the stock throttle linkage and mount fuel injectors into the manifold somehow.

I run megasquirt on my car right now, which is a batch FI system which isnt ideal for individual throttle bodies, but it can be done. What I would be interested in is a cost versus benefits look. The low manifold pressure that is supplied to the ECU would make idle tuning a little more difficult, but thing like town driving, throttle response, gas milage and actual power output would be interesting.

I figure it would be a sweet way to have the look, sound, and instant umph of carbs with a little modern touch. :twisted:
mdrburchette
Posts: 5754
Joined: Wed Jan 25, 2006 5:49 am
Your car is a: 1972 Fiat 124 Sport
Location: Winston-Salem, NC

Post by mdrburchette »

James, I talked to the guys at Redline Weber about using the TB's instead of my 40 IDF carbs and for $2600, which includes two cast tb's, all sensors, ecu, fuel pump, regulator and distributor, there was no real hp gain. The only advantage would be driveability until the engine's warmed up and maybe better throttle response in lower range. I think I'll just stick with my carbs.
Joe Clemente
Posts: 151
Joined: Wed Jan 25, 2006 1:35 am
Location: Vancouver, B.C. CANADA

Post by Joe Clemente »

mdrburchette wrote:James, I talked to the guys at Redline Weber about using the TB's instead of my 40 IDF carbs and for $2600, which includes two cast tb's, all sensors, ecu, fuel pump, regulator and distributor, there was no real hp gain. The only advantage would be driveability until the engine's warmed up and maybe better throttle response in lower range. I think I'll just stick with my carbs.
Not to sound sceptical, but it makes perfect sense that someone who's bread n butter is made up more from carb sales than FI might suggest that. It's a good selling job... 8)

I won't disagree that price is a major factor when considering FI because a good system is more expensive than carbs. And let's face it, carbs make inexpensive horsepower, and they're simple which is why carbs are such an appealing option. But the rest of what you've said, with all due respect, is inaccurate. Both systems have their advantages and disadvantages. A simple dual carb setup for the street is nice, cheap, easy, and works well. But don't mistake them for being superior to FI, they're better than a single throttle setup but they are not better than multiple TBs.
FI systems provide benefits in more than just drivability, although that alone is huge. Throttle response, assuming the FI is correctly set up is better everywhere, not just down low. Ever try getting a motor with big cam specs and carbs to idle consistently? How about emissions testing? These are some other advantages that electronic engine management provides. As for that power? best thing to do isto obtain a quatitative measure from a dyno. As an example, my buddy just switched from 40mm SK racing carbs on his GT-4 car to TBs with megasquirt (not my personal favorite) and horsepower figures went through the roof in comparison.

The idea of using individual motorcycle TBs is not new but it certainly works well. I've seen a number of of these setups and the manifolds were simple automotive tubing between the TBs and a truncated stock manifold.
Point is, this is not an expensive conversion to do and it works great, Though I've not seen anything like it on a Spider, I suspect it would not be to complicated to do.
There are naturally more pricey FI systems available and they will deliver big gains but you'll probably spend as much for this equipment as you did to buy your whole Fiat. It is also more time consuming to set up a good FI system correctly but there are certainly measurable benefits.
Hjulen

Post by Hjulen »

Thanks everyone.

How would the low vacuum from the throttle bodies affect the brake booster? (I am not familiar with home the booster uses the vacuum but it is something that I thought should be considered.)

On my car I will be installed EDIS to compliment the Megasquirt in a few months, total cost to me (including the cost of two computers) will be somewhere around $700 with fueling mappable fuel and ignition.

But even like Joe mentioned MS isnt exactly some people's favorite. :wink:

What is the tube spacing on a stock FI manifold? (I am a couple of hundred miles away from my car right now) It would be interesting to search some itbs with similiar spacing
pastaroni

Post by pastaroni »

how much is a 40mm ITB these days?
Hjulen

Post by Hjulen »

TWM induction lists the throttle bodies on their price list for $330 a pair, (with two pair needed for a spider). That doesnt include linkage, injectors, fuel rail, ect. I am not sure what redline weber charges just for the ITBs, but I emailed them to find out.

Motocycle tbs from a suzuki gsxr or similiar cost under 100$ on ebay, and if you used the stock fuel rail and truncated the manifold, as long as the spacing between the throttles was right and you had a programmable ecu it should work.
mdrburchette
Posts: 5754
Joined: Wed Jan 25, 2006 5:49 am
Your car is a: 1972 Fiat 124 Sport
Location: Winston-Salem, NC

Post by mdrburchette »

The Redline was 200 a piece for cast and 500 a piece for billet.
pastaroni

Post by pastaroni »

Densie, is that for the IDF type or just a single throat?

I have been considering making my own. I don't have the money to spend on stuff.. then again, I probably don't have the time to make my own either... :/
Hjulen

Post by Hjulen »

Do you know if that was with rails and linkage (the kit the least on the website I guess)?
mdrburchette
Posts: 5754
Joined: Wed Jan 25, 2006 5:49 am
Your car is a: 1972 Fiat 124 Sport
Location: Winston-Salem, NC

Post by mdrburchette »

The price was just for the IDF tb's. The $2600 was for the total kit, but don't recall the intake manifold being part of that price. I was surprised and a bit disappointed when the guy told me there would be no gain performance wise over the dual carbs. It would be nice to see dyno results with both setups.
CoupeFan
Posts: 41
Joined: Wed Jan 25, 2006 10:26 am

Re: Individual Throttle Bodies

Post by CoupeFan »

Hjulen wrote:
I run megasquirt on my car right now
James, which version are you running? I'm about ready to make the jump. I am interested in keeping it cheap at the moment, so the 2.2 version will have to do. However, I fear the 8x8 tables will leave me with a few gaps across the rev range. I would like the 12x12 of the newer versions. Here's where I can't get a straight answer, can the firmware of the older 2.2 be upgraded to takes the 12x12 tables?
Cheers,

Cesare Consaga
1973 124 Sport Coupe
1982 X1/9
2015 Fiat 500e
2012 Fiat 500
Hjulen

Post by Hjulen »

James, which version are you running? I'm about ready to make the jump. I am interested in keeping it cheap at the moment, so the 2.2 version will have to do. However, I fear the 8x8 tables will leave me with a few gaps across the rev range. I would like the 12x12 of the newer versions. Here's where I can't get a straight answer, can the firmware of the older 2.2 be upgraded to takes the 12x12 tables?
Your damn right it can be upgraded to run the new tables! Right now I am running the v2.2 board with MSnExtra firmware. The MSnE gives you all the software advantages of the upgraded MSII chip, without the cost.

Here is the website for MSnE: http://megasquirt.sourceforge.net/extra/

Follow the instructions for a fuel only installation. Be sure you read everything carefully, its not hard, but it is easy to get lost when they start talking about different code versions and other things. I got my car running using the standard MS code with 8x8 tables then switched over to the 12x12 without much hassle.I will eventually use the ignition code in the extra firmware to run my EDIS ignition setup once I get around to it.

There is nothing wrong with the 2.2v. There were only two big things that I ran into: The first to how to get the ECU to turn on the fuel pump, which can be fixed with a well tested mod to the circuit board. The second is that you need to get external resistors or the flyback board to really run Fiat injectors properly. I am using the PWM feature right now, but since it is a software solution it can have a tendency to overload the circuits. No problems so far though.
spidertoronto

Redline Weber

Post by spidertoronto »

Hi Guys,

I'm a new poster from toronto Canada. I've been looking into the same throttle body questions you all have. To clarify, Redline Weber sells itbs for fuel injected applications too. See http://www.redlineweber.com/html/thrott ... _mount.htm.
So I don't know that they'd benefit from telling you itbs won't get you any more bhp than the dual carb equivalent. Makes sense to me since they both do about the same job right (at high revs suck in as much fuel and air as possible)? I've read the efi throttle bodies have quicker throttle response. But anyways I'm looking at them because for an efi fiat spider owner it might be the only way to get a performance boost without opening up the engine. That is assuming you don't want to slap on a turbo or supercharger. I'd still like to go with the motorbike itbs.Cheap.
My question is if I had a 100hp Fiat 2000 what kind of hp gain would I get with either setup. About 20hp?
Hjulen

Post by Hjulen »

You know I have been wondering about kind of gains it would produce...

...doubt it would be as much as 20hp over dual carbs, but I am sure the powerband will be a hell of a lot more fun.

I have been talking with Jason Miller over at millersmule.com about making some ITBs and he seems to think it won't be as hard to machine as it might be expected.

As for me I think the primary focus for right now will be getting the FORD EDIS ignition installed along with some HC pistons and other goodies. Then once the summer comes around, and hopefully Jason's TB design as well, then start checking those out.
bandit

Post by bandit »

Hey James

What kind of TBs are you running with your TC or is it the Factory
FI system with A MS ECU ?

Dan
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