Hello everyone. I have a question I'm hoping someone may have the answer to. I recently acquired an L&M twin 72 for my 13 GT500. It was going on to compliment a few other mods the car has already. JLT 127mm, 10% lower and bpa elbow. These were all installed a while ago before I purchased the car and it was tuned from some shop out in Vegas. Car has run great the last 6 months I've had it but was looking for a little more. I installed this throttle body and from I had read it wasn't supposed to require a tune but I'm not so sure now. With this throttle body the idle hangs really bad when warm. The longer you drive it the worse it is. It also idles around 1300 when warm. When it's cold it behaves like stock. I swapped the electronics thinking maybe that may be it but it didn't help. It's not binding because I logged etc desired vs etc actual and they match all the time it's just rpm desired vs actual that don't. Anyone have experience with this? Thanks in advance.
Question about L&M twin 72mm throttle body
- Thread starter SN95GTMustang
- Start date
If you were going from the OEM stock T/B, it would require a tune..
First off, you're looking at a 44% increase in effective throttle area. It needs a tune. Anyone who tunes your car will be starting from scratch for a tune revision, unless you can find the original tuner that can put his hands on your tune file.
According to VMP's deep dive into throttle bodies, the Ford actuator motor is on the small side to properly control the throttle blades on larger throttle bodies. One issue they cite is the high engine vacuum with the stock cams. They had a 72mm at one time and took it off the market. The largest twin they market today is a 69mm. I have not heard any complaints on this throttle body and their 67mm has a proven track record as to reliability.
You may find someone to tune it, but it might be in for a long painful search with no guaranty it will ever run right. If this is primarily a street car, I'd pick something smaller and forego the small power pick up at redline. Tuner's are not interested in dealing with continual tune tweaks that are not worth their time and effort, so you may have a hard time finding someone is willing to touch it. Then again, you may find someone that nails it.
The 69mm is still a 32% increase in ETA, BTW. FWIW, a 65mm or a 67mm can run okay without tune revisions. It will run better with a tune, but it's an alternative to retuning the car.
According to VMP's deep dive into throttle bodies, the Ford actuator motor is on the small side to properly control the throttle blades on larger throttle bodies. One issue they cite is the high engine vacuum with the stock cams. They had a 72mm at one time and took it off the market. The largest twin they market today is a 69mm. I have not heard any complaints on this throttle body and their 67mm has a proven track record as to reliability.
You may find someone to tune it, but it might be in for a long painful search with no guaranty it will ever run right. If this is primarily a street car, I'd pick something smaller and forego the small power pick up at redline. Tuner's are not interested in dealing with continual tune tweaks that are not worth their time and effort, so you may have a hard time finding someone is willing to touch it. Then again, you may find someone that nails it.
The 69mm is still a 32% increase in ETA, BTW. FWIW, a 65mm or a 67mm can run okay without tune revisions. It will run better with a tune, but it's an alternative to retuning the car.
Have you datalogged it?
I would never trust a tune a car came with unless I personally verified it with my tuner.
Sounds like a good excuse to get a tune health check and possible retune.
These cars do pick up big time from bigger TBs.
-J
That's pretty sound advice, especially if you don't know the car and/or its owner. You never know what the owner may have had on the car when the tune was developed, and what could have been swapped out for the sale. These engine are anything but cheap if things go bad.
I had this TB years ago, actually both the L&M 66 and 72. They used to advertise no tune required, so I tested this "fact". Indeed, both ran well with stock TB calibrations, which I was happy about because back then, I knew nothing about tuning TBs. Years later, I came across an Effective Area data for the 72mm>>
Being how my car ran fine with stock calibrations, I did not know what to expect by changing the above, but I tried it. Please note to your tuner that any changes in this table should be in conjunction with changes in the FF TA Prediction Angle table. It is basically an inverse of the numbers above. If your tuner knows his stuff, he will already know this... Just throwing it out there for you, as knowledge is power!
Anyways, I made these changes and my car ran no better or worse. Datalogs showed no significant changes, so I'm really at a loss on why. My recommendation is to copy the above table and try it.
Being how my car ran fine with stock calibrations, I did not know what to expect by changing the above, but I tried it. Please note to your tuner that any changes in this table should be in conjunction with changes in the FF TA Prediction Angle table. It is basically an inverse of the numbers above. If your tuner knows his stuff, he will already know this... Just throwing it out there for you, as knowledge is power!
Anyways, I made these changes and my car ran no better or worse. Datalogs showed no significant changes, so I'm really at a loss on why. My recommendation is to copy the above table and try it.
Thanks for the info guys. Yeah I decided to just get it tuned and I'm having it tuned by Matt Honeycutt from Juggernaut performance now so car should be worlds better soon.
Side note. What's weird with this TB is that it actually ran really good on whatever tune it had in it. The only issue was that after it gets hot from a few miles of driving it's like a switch flips, it holds the idle super high during coast down, like 2k to 3k, till you stop. Then it comes down to like 1kish rpm and holds the rpm up during every shift. If I pull over and clear kams it's good again for a mile or so unless I let it cool completely. It's so weird. I logged the issue today so let's see what happens.
Side note. What's weird with this TB is that it actually ran really good on whatever tune it had in it. The only issue was that after it gets hot from a few miles of driving it's like a switch flips, it holds the idle super high during coast down, like 2k to 3k, till you stop. Then it comes down to like 1kish rpm and holds the rpm up during every shift. If I pull over and clear kams it's good again for a mile or so unless I let it cool completely. It's so weird. I logged the issue today so let's see what happens.
Have your tuner lower all five CIB scalars. If he gives you a blank stare, contact me and I'll give you the exact numbers to give to him to change.
Willie
Willie
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..............................Find another tuner !!
I have confidence in the tuner. He just got started with thr car and has a good reputation. This is just info I'm trying to find for me.
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