Using a 5.0 Mustang TB

Sharkey · Post by **Sharkey** » Mon Jul 16, 2001 7:08 pm

Is anyone using a 5.0L Mustang throttle body on their EFI set-up? I've heard of a few people recommending this design and I'm sick and tired of my poor drivability with four huge 48mm butterflies. Since my car is turbocharged and all the incoming air has to pass through the small 40mm (?) turbo outlet anyway, it seems absolutely pointless to run four huge 48mm butterflies.

NOBODY yet has been able to explain to me why ACVW tradition is to run dual 2 BBL 40-48mm carbs or throttlebodies when a large V8 can get away producing nearly 300 HP using only a single 55-65mm throttlebody.

PapaG · Post by **PapaG** » Tue Jul 17, 2001 9:46 am

You can check the hardcore vw forum for info. It's watercooled but a lof of talk on aftermarker FI. You might also check the DYI-EFI site. I don't have the url handy but it should be easy to find. Adapt a Mustang, Chey or (god forgive me) a honda TB. Why? Because you can get them cheap> at least compaired to VW-german stuff.

I am working on a aircooled and watercooled project. Both in the planing stages.
Good luck....

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RIchard
Lost in Texas with Bluebonnets and Bluebell Icecream

Chuck Schneider · Post by **Chuck Schneider** » Tue Jul 17, 2001 9:45 pm

Sharkey your poor drivability isn't because of four butterflies it's because of bad programming in the fuel injection computer. The Map values are wrong for the motor. Just my 2 cents. If anything the motor should be more responsive with 4 butterflies.

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12.70 @ 104

JohnConnolly · Post by **JohnConnolly** » Tue Jul 17, 2001 10:32 pm

one problem with huge TBs like that is you are at max airflow at like 30% throttle opening. This means your gradient of TPS is too steep to be of much use (no airflow difference between 40% TP and 80%TP, for example). Max power is unchanged but drivability sucks.

Veepster · Post by **Veepster** » Wed Jul 18, 2001 9:54 am

I use the 5.0L TB and have great success....let me know any questions you have...you can check out some pics of it at www.teamgodspeed.com

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Peace.............BartG www.teamgodspeed.com

Sharkey · Post by **Sharkey** » Wed Jul 18, 2001 6:17 pm

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Chuck Schneider:
Sharkey your poor drivability isn't because of four butterflies it's because of bad programming in the fuel injection computer. The Map values are wrong for the motor. Just my 2 cents. If anything the motor should be more responsive with 4 butterflies.<HR></BLOCKQUOTE>

I don't agree. My WOLF 3D shows that my TPS is running at around 2-3% open when I'm cruising along in 3rd gear at 60 km/h. It is my opinion that the four butterflies don't provide a nice linear airflow between this position and idle, hence my accel/decel surging if I move the gas pedal even just a little bit.

I still haven't found someone that can explain why four 48mm TBs are even necessary when all my airflow comes out of a single 40mm ID turbocharger outlet.

Steve Arndt · Post by **Steve Arndt** » Thu Jul 19, 2001 8:41 am

Try building an extension onto your gas pedal. That gets you more pedal travel per cable movement. It helps off road to control it in the rough stuff.

Post by **Tom Notch** » Thu Jul 19, 2001 12:34 pm

4 TBs are not nessecary in Your application, and it is what You purchased. My atmos engine suffers none of the off idle problems you are having and I have even Bigger TBs. John is right on the flow #s and if you were to look at my Haltech manual and the maps out of my system you would see that at approx. 50% open (or closed) the maps are bassically flat from there on up, but that doesn't help your stumble.

One Haltech equipped car I was working on had similar stumbles caused by too much fuel enrichment, ie the accel values were too fat and lean can cuase the same. Maybe the tps is not a wide enuff range or has a bad spot in the windings. What is the CB supplied part like? dang, back to work, more later.

Another possibility is too large of injectors and not being able to get the right idle mixture because of this. I am running 36 pound units and don't have the problem but have heard of that happening. Just not sure of what system was being used.

Is there a possibility of the map sensor causing this? On the haltech there is 3 different ones called out to be used-one for atmos. and 2 different ones for boosted engines (depends on the amount of boost).

I just find it really hard to believe your TBs are causing the problem. There are just too many 48s and larger being used all over the world in numerous applications.

btw, someday I'll give my spin on individual throats, just no time now.

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Tom Notch
Tom's Old VW Home

[This message has been edited by Tom Notch (edited 07-20-2001).]

Steve Arndt · Post by **Steve Arndt** » Fri Jul 20, 2001 8:41 am

http://jubjub.mine.nu/CB_throttle_bodies.htm
pics of the CB TPS. I think it is a plain GM part so it should last as long and be as smooth on the curve as any factory efi car requires. . .

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Tom Notch: What is the CB supplied part like?

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