GS 400 cams and exhaust headers
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4th Gear
Joined: Apr 2026
Posts: 4
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GS 400 cams and exhaust headers
Anybody done this ? Installing Kelford 208-B. Most gains and still street drivable.
p
will work without tune…. But leaving HP on the table….
anybody know a piggyback solution or shop that can program a full ECU… would love to ditch CAT’s in process.
p
will work without tune…. But leaving HP on the table….
anybody know a piggyback solution or shop that can program a full ECU… would love to ditch CAT’s in process.
Pole Position
Joined: Nov 2018
Posts: 2,083
Likes: 580
From: CA
I don't think there are any tuning devices that work with modern Toyota ECUs. Other than full stand alone. From what I hear, the factory ECU fights and changes air/fuel ratio settings back when using piggy back units. I like the idea of a mild cam swap. ECU won't know the difference, the MAF will just tell it to fuel more for the extra incoming air.
Racer
Joined: May 2017
Posts: 1,536
Likes: 356
From: Utah
The best option is an Apex’i NEO, make sure to get the one for a V8, they discontinued these about a year ago, but u coat still find them, and there is a whole thread in the “How To” section with instructions for how to wire up to your car. It’ll be a great for adjusting the timing and AFR to accommodate the Cams and Headers, I would love to get some cams in mine, and some forged pistons with a 12:1 compression ratio, get the most of an N/A engine.
Thread Starter
4th Gear
Joined: Apr 2026
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74 ft lbs torque
I purchased a rear end from a GS 300 which is 3.96 and is a huge improvement over stock 3.26….
a mechanical advantage of about 74 ft lbs of torque.!!
now…. At 80 on hwy it does sit at 3000 rpm.
a mechanical advantage of about 74 ft lbs of torque.!!
now…. At 80 on hwy it does sit at 3000 rpm.
Pole Position
Joined: Nov 2018
Posts: 2,083
Likes: 580
From: CA
It's funny, I did just the opposite. I put a GS400s 3.26 ring & pinon in my GS300 to bring the rpm down and to have longer gears before having to shift. (I am manual swapped and turbo though). As your power increases you outgrow lower (numerically higher) gear ratios.
Thread Starter
4th Gear
Joined: Apr 2026
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Manual swap
That’s cool…. What kind of numbers did you end up with ? Thinking I wanna do a supercharger.
when my trans gives out….254k and counting.
It’s been treated well, with oil changed every 30-40k… But I drive like a mad man in the TN mountains daily. 2300 ft of climbing everyday. Lots of turns.
ill do a manual swap !! and need all the help I can get.😜
when my trans gives out….254k and counting.
It’s been treated well, with oil changed every 30-40k… But I drive like a mad man in the TN mountains daily. 2300 ft of climbing everyday. Lots of turns.
ill do a manual swap !! and need all the help I can get.😜
Last edited by 3boysdad; May 26, 2026 at 08:20 PM.
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