Idle speed question and an update with some real-world stats

What idle speed do you run your Gen 3 Hemi at?

  • 600

    Votes: 0 0.0%
  • 700

    Votes: 0 0.0%
  • 750

    Votes: 0 0.0%
  • 800

    Votes: 0 0.0%
  • 950

    Votes: 0 0.0%
  • 1000

    Votes: 0 0.0%

  • Total voters
    3
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GoldSwinger71

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Question for you who've been running for a bit with their swaps -

What idle speed do you have set up in your ECU? My tuner set mine up at 900, which is fine (the new tune fixed many many issues and now it runs like a bastard!), but I'm seeing folks who are running factory setup with idles as low as 600?

Also - wanted to share some results - with my 6.4, 727, Dana 60 3.55 and a nice lean-out at steady cruise, I was seeing results as high as 20MPG @ 65MPH (3200 RPM), which is pretty stunning for a car with 615HP.

With the 235's it's still a beast to handle, but I did a test launch - Power braking up to 2500, wheel spin off the line, and left the car in D which shifts at 5500RPM, well below peak power - I got a GPS verified 12.87 @ 109MPH. Considering that the redline on this setup is 7000 and it didn't entirely hook, there's definitely more power on the table.

Monday she's off to the body shop for a little re-spray to fix some defects in the paint from the previous owner's half-assed job, NEW CORRECT BUMBLE-BEE STRIPE (angled, not vertical) new windshield and seal (BTW if you've been waiting for a green tinted one from Auto City Classic in Isanti MN, they're in stock now!) and helping adjust the hood fitment and the side glass alignment. I was promised it was a "week or so" job so I'm going to hold him to it.

Since I don't trust ANYONE, I'm going to put a battery powered GPS tracker in the car under the package tray which provides 10 second updates when in motion. The car shouldn't have to leave the body shop and if there's any temptation to do a "test drive" I'll be able to shut that down REAL quick. The trackers are pretty cheap, it's the subscriptions which are expensive.

https://www.amazon.com/LandAirSea-Waterproof-Magnetic-Personal-Location/dp/B06XVZ6Y4T?tag=fabo03-20

But if you want to do something like that with your car (classic or otherwise) they offer monthly subscriptions. A $50 bill is cheap to know if someone is taking out your car to rag on it, versus the heartbreak of an insurance deductible. You can choose to only activate it when you plan on being away from the safety of your garage for any extended period of time.

Anyway - hope all of you are having good progress waking cars up for Spring. I'm hoping to do some fun things this year, including getting drone video footage of the car in motion, and some lovely burnout pics.

-Daniel
 
I've recently changed my idle, but I play around with it some. I have an early 5.7 with a manual though, so probably not quite apples to apples. I do have an Inertia Motorsports SRT Max Plus cam in it, so it's got a little lope, but nothing super crazy. Hot I used to have it idle around 700-750, but I had some oscillation issues, so it would swing between 600-800 or so, and not just in a loping way. I've redone my tune recently after finding a stock tune for a similar year engine and doing what I could to translate from the HP Tuners tables to the Megasquirt I have in the car. Based on that I dropped the idle down to 625-650 and it's been okay. I did also activate the "idle timing" setting that lets the computer change the timing to get the idle more stable. Less oscillation now, so it can idle lower with less issue of it dropping so low as to die like it might have before.
 
Question for you who've been running for a bit with their swaps -

What idle speed do you have set up in your ECU? My tuner set mine up at 900, which is fine (the new tune fixed many many issues and now it runs like a bastard!), but I'm seeing folks who are running factory setup with idles as low as 600?

Also - wanted to share some results - with my 6.4, 727, Dana 60 3.55 and a nice lean-out at steady cruise, I was seeing results as high as 20MPG @ 65MPH (3200 RPM), which is pretty stunning for a car with 615HP.

With the 235's it's still a beast to handle, but I did a test launch - Power braking up to 2500, wheel spin off the line, and left the car in D which shifts at 5500RPM, well below peak power - I got a GPS verified 12.87 @ 109MPH. Considering that the redline on this setup is 7000 and it didn't entirely hook, there's definitely more power on the table.

Monday she's off to the body shop for a little re-spray to fix some defects in the paint from the previous owner's half-assed job, NEW CORRECT BUMBLE-BEE STRIPE (angled, not vertical) new windshield and seal (BTW if you've been waiting for a green tinted one from Auto City Classic in Isanti MN, they're in stock now!) and helping adjust the hood fitment and the side glass alignment. I was promised it was a "week or so" job so I'm going to hold him to it.

Since I don't trust ANYONE, I'm going to put a battery powered GPS tracker in the car under the package tray which provides 10 second updates when in motion. The car shouldn't have to leave the body shop and if there's any temptation to do a "test drive" I'll be able to shut that down REAL quick. The trackers are pretty cheap, it's the subscriptions which are expensive.

https://www.amazon.com/LandAirSea-Waterproof-Magnetic-Personal-Location/dp/B06XVZ6Y4T?tag=fabo03-20

But if you want to do something like that with your car (classic or otherwise) they offer monthly subscriptions. A $50 bill is cheap to know if someone is taking out your car to rag on it, versus the heartbreak of an insurance deductible. You can choose to only activate it when you plan on being away from the safety of your garage for any extended period of time.

Anyway - hope all of you are having good progress waking cars up for Spring. I'm hoping to do some fun things this year, including getting drone video footage of the car in motion, and some lovely burnout pics.

-Daniel
Mine is around 850-900PRM idle, but in all honesty, I could work on it more.

BTW, I hope you lifted on that quarter mile run on the GPS, because there's no way you have 615HP and only went 109MPH. My early 5.7 with a cam and home ported heads went 114MPH in a 3500lb car.
 
Traction was a limiting factor. :)

I’ll be dialing in my launches going forward , and the temperature of the asphalt was probably… 55F?
 
Mine is around 850-900PRM idle, but in all honesty, I could work on it more.

BTW, I hope you lifted on that quarter mile run on the GPS, because there's no way you have 615HP and only went 109MPH. My early 5.7 with a cam and home ported heads went 114MPH in a 3500lb car.
Agreed!! I had a 2011 Shelby GT500 that I had a hard time getting into the 12's BUT it did run 117.5 MPH all the time... 1st and 2nd gear was useless with the stock tires I had.
That was rated at 540HP.
 
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