2018 truck manifold on a gen 2 coyote

[K4fxd]

Gen 2 Coyote (2017 GT, 5.0L) — VCT / Cam-Timing Tuning Findings

Platform: 2017 Mustang GT, Gen 2 Coyote 5.0L, MAF-based, HP Tuners + PCMtec Fuel: Costco 93 (E10) Method: Street pulls, 2nd gear (validated for resolution + full load), datalogged at 50–67 Hz Goal: Understand and optimize the Ti-VCT Optimum Power cam schedules; evaluate a 2018 F-150 truck intake manifold on the Gen 2 long-block.


This is a shared-knowledge writeup of what I found through structured, one-variable-at-a-time testing. Numbers are from my own datalogs on my combo — treat as a starting reference, verify on your own car. Your mileage will vary with heads, cam, manifold, and fuel.


KEY FINDINGS (the short version)

1. Exhaust cam timing does essentially NOTHING for airflow on this combo. Verified three ways: added overlap (no gain), reverted to stock (no gain), and it matches tuner consensus. The exhaust is a dead lever for WOT airflow on a cross-plane Coyote with these manifolds. (It still affects idle/emissions/NVH — just not WOT airmass.)
2. Intake cam ADVANCE is the working lever, but only below a crossover ~4500 rpm. Holding the intake at full advance (−20) through the torque zone (3500–4250) gained measurable airmass. Holding full advance PAST ~4750–5000 lost airmass up top — the engine wants the intake to swing to RETARD up high for late-IVC "ram" cylinder filling.
3. The VE crossover is ~4500 rpm. Below it: advance wins (early IVC, higher effective compression, more midrange fill). Above it: retard wins (late IVC ram effect). A "hybrid" schedule — hold advance to ~4500, then progressively retard up top — beat both stock and full-advance across the ENTIRE rpm range.
4. The transition zone (4500–5300) is FORGIVING. A locked −8 probe made the same airmass as a lagged ~−12. Anywhere in that range works about the same; what does NOT work is holding −20 too long. Good news: you don't need perfect cam tracking through the transition.
5. Phaser slew lag is real in low gears. In 2nd gear the intake phaser lagged commanded position by up to ~8° through steep transitions (delay of ~250–300 rpm before it starts moving, then ~5° per ~150 rpm). Lag shrinks in higher gears (slower rpm climb). Because the transition zone is forgiving, the lag doesn't cost measurable power — but it means a schedule dialed in 2nd gear behaves slightly differently in 3rd/4th.
6. Exhaust cam schedule wastes phaser motion. Stock commands a whipsaw (e.g., 12→21→16 across 3000–4000) the phaser can't even execute in 2nd gear, for zero airflow benefit. Flattening the exhaust to a steady ~14 is airflow-neutral AND mechanically calmer (less pointless slewing).
7. Inferred Octane pegged at 91 while running 93. The ECM assumes worse fuel than you're feeding it, leaving spark headroom unused. Potential safe timing to capture by correcting the octane assumption (verify at WOT — cruise ≠ WOT knock behavior).

CAM TIMING REFERENCE (Gen 2 command frame)

Base valve events (from tune): IVO 340, IVC 239, Intake Max −20, EVC 369, Exhaust Max 50.


Gen 2 intake phaser: parks at 0, commands −20 advance / +30 retard (50° total travel, bidirectional).

• Gen 1 was single-direction (full 50° one way). Gen 2/3 split it: 20 adv + 30 ret.

.050" duration: ~211° both cams (from mustang6g/SVT data; the "260/263" in some spec guides is seat/advertised timing mislabeled as .050", not real .050").


MY BEST INTAKE SCHEDULE (Optimum Power, IVO angle vs RPM)

Negative = advance. Derived from airmass + MAF-to-load VE ratio testing.

RPM	Intake
2500	−11
3000	−20
4750	−18
4900	−12
5100	−8
5300	0
5800	+7
6250	+11
6500	+13
7000	+15
7250	+15

Logic: hold advance through the torque zone (gain), release through the forgiving transition, progressively retard up top for ram filling. This schedule made airmass climb to the rev limiter with throttle open and timing being ADDED (no knock) — the engine wants to rev.


Notable: this independently landed very close to the verified GT350 (5.2 Voodoo) factory OP intake schedule. Two different approaches (my street airmass logging vs Ford's development) converged on nearly the same intake curve. Good confirmation the strategy is sound.


2018 TRUCK MANIFOLD ON GEN 2 — NOTES

• Truck manifold peak airmass on my Gen 2: ~40 lb/min with the dialed intake schedule (~400 raw / ~470+ crank hp equivalent, DA-corrected). NOT a low-flow manifold — right in healthy Coyote territory.
• Truck cal is Speed Density (MAP); the car is MAF. The cam strategy transfers as a hypothesis; the airflow calibration does NOT (different sensing architecture).
• Truck OP exhaust runs a big midrange overlap spike (38° @ 3000). GT350 runs 49.5° @ 3500. Both are "big midrange overlap" manifolds — but on my combo, exhaust did nothing for airflow, so I didn't chase it.
• Long-block deltas (Gen 2 car vs Gen 3 truck): 11:1 vs 12:1 compression, 200cc vs 205cc runners, 1.468" vs 1.484" intake valve, 0.511" vs 0.551" lift, 7000 vs 7500 redline. The 205-vs-200 runner match means minimal manifold-to-port step (forgiving direction) for an unported swap.

METHOD NOTES (what made the data trustworthy)

• MAF reads true across the manifold swap — fuel trims stayed flat (STFT ±1%, LTFT −1 to −2%), because the inlet tract (MAF housing, tube) is fixed and upstream of the manifold. Watch STFT for MAF integrity; if it develops rpm-localized bias after an intake swap, the sensor's being disturbed.
• Density altitude correction ("poor-man's dyno correction"): compute DA from local METAR (temp/dewpoint/altimeter) at run time; normalize airmass/power between sessions by density ratio. A 1,500 ft DA swing is worth several % power — bigger than the cam deltas you're chasing, so correct for it or match conditions.
• Match logged air temp between compared pulls. Heat soak (especially from more cruise before a pull) warms intake air and confounds comparisons.
• 2nd gear is fine for data — full load, good resolution. Higher gears reduce phaser lag but add speed/risk.
• Log airmass (lb/min) as the verdict — it's a direct measurement. Same-session pulls need no correction; cross-session needs DA normalization.
• MAF-to-load ratio (measured airflow ÷ theoretical) is a useful VE / MAF-integrity check — shows where breathing efficiency peaks and confirms the MAF reads true.

WHAT I'D TELL SOMEONE STARTING THIS

1. Log real airmass and treat it as truth. Don't trust a scanner HP gauge without verifying its math (mine had a unit-scaling bug reading ~30% low).
2. One variable at a time. Distinguish what you've verified (your own data) from what you trust (secondhand).
3. Exhaust cam: don't waste effort chasing it for airflow. Check it, then leave it flat.
4. Intake cam: hold advance in the torque zone, retard up top. Find your VE crossover (~4500 on mine).
5. Correct for weather (DA) or you'll chase atmospheric ghosts.
6. The phaser lags in low gears — but the transition zone is forgiving, so don't over-obsess about perfect tracking there.

Shared freely. Verify on your own combo — this is my data on my car, offered as a starting point and a method, not gospel. Corrections and additions welcome.

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[K4fxd]

I will continue to refine this tune by bracketing spark and fueling. I will also add drag strip times and MPH. So far I find the manifold is as good or slightly better than the 2017 gt intake manifold. I will also A/B this against the gt350 intake manifold and show the real world differences.

Trying to find out if the higher avg torque manifold out performs the higher peak HP manifold on the track.

Stay tuned

 

[Cobra Jet]

Great tech write up!

 

[engineermike]

Awesome work! Just a few comments to add to the discussion:

- For some reason, Ford has the Gen3 retarding all the way to 24 at very high rpm. I've found indirectly in 2 cases that it appeared to gain power by limiting this to 15-18 instead of 24. If I'm right, I have no idea why Ford would retard it so much. Everything else I've seen, from Boss 302 to GT350 to Gen2 only goes to around 15 up top.

- FYI, S650 Intake cam went back to Gen1 for the "home" angle.

- It makes sense that exhaust cam timing didn't affect airflow. It's only chance to affect it is during overlap and the effects would be small if any. The only thing it would affect is the expansion ratio (later better) or ensuring the pressure has blown down before the exhaust stroke starts (earlier better), but by all accounts, 15 works in almost every case with only minimal gains possible beyond that.

- I don't think that inferred octane channel does anything in the Mustangs.

- Something fun to do is translate all the numbers into old-school duration, LSA, and advance. You get some wild stuff, but it really emphasizes how much of a compromise fixed cam timing really is.

 

[K4fxd]

This is my best guess since I have not used a degree wheel on an actual engine.


INSTALLED LSA (varies with rpm — cam degrees), intake schedule with exhaust at 14:

RPM Intake Exhaust Approx LSA
3000 -20 14 ~99.0 (tightest / highest overlap)
3500 -20 14 ~99.0
4000 -20 14 ~99.0
4750 -18 14 ~100.0
5000 -8 14 ~105.0
5300 0 14 ~109.0
5800 +7 14 ~112.5
6000 +9 14 ~113.5
6500 +13 14 ~115.5
7250 +15 13 ~116.2 (widest / lowest overlap)

 

[K4fxd]

Something changed in my tuning software that reinstalled a 7256 rpm limit that I cannot find. The data shows the manifold still increasing power at that rpm. Very frustrating and I am working on a solution. I'd like to find the peak for this manifold. It already flows better than anyone gives it credit for, and more than I thought.

 

[K4fxd]

These are the numbers crunched. I was able to defeat the rev limiter.

I need to get to a dyno or a drag strip. Anyway here is the raw data using maf & load to approximate VE. Not saying I believe it but the numbers are there.

 

[K4fxd]

Here is a calculated dyno graph. The seat of the pants supports this as it wants to keep reving

 

[Rick#7]

I tried to research this manifold a while back with a frustrating lack of verifiable data among Mustang forums, the general consensus being that since it's a truck manifold, it's going to trade top end HP for low end torque. However, after scrolling through dozens of threads on various F150 boards and comparing every posted dyno chart I could find, I came to the opinion that the 18+truck mani likely flows just a little better than the '15 GT mani, but due to runner design, shape, length, volume, it still had an rpm range very similar to the 15 Mustang with the potential for slightly increasing power across the board and possibly extending the top end rpm range.

My goal in that research was not chasing power gains, my primary objective was to find an economical solution to the failed manifold in my nephews 15 Mustang, which fell victim to the infamous IMRC shaft failure. At that time (maybe 2 years ago), 2018 truck manifolds were about the cheapest part available, with new take-offs going for $99 shipped, while replacement 2015 intakes were listed at $650 with a backordered status and no shipping date available. The dealer was pushing 2018 Mustang manifolds as a replacement, going for $499. I don't know if those prices are still valid today, but that's not really the point. I believed then, and still do, that if you need to replace the manifold on a 2nd gen coyote due to failure of the stock part, that the gen 3 truck manifold is a viable and economical option that is often overlooked simply because it's a truck manifold.

So, in your evaluation of the truck manifold, do you think my opinion of the performance characteristics is close to reality, or is it like everyone else says it is, only good for a truck?

 

[K4fxd]

You are spot on in your opinion. This manifold, from my testing, slightly better than the gen 2 gt manifold, and is a great replacement for a broken gen2 gt. OZ tuning has a manifold shoot out on facebook that validates my findings. I know they used a gen 4 truck but the trend is the same. Large torque increase in the low midrange and a flat HP curve above 5000 RPM. I need more testing, IE drag strip and or dyno, but it looks like on the mustang the manifold climbs in power after 5000.

Is this the best manifold for power? NO, is it a great replacement for a gen 2 mustang? IMO yes. It got a bad rap because the gen 2 truck manifold was a turd. Ford put some engineering time in both the gen 3 gt, and truck manifolds.

Honestly I am surprised it is carrying power as far as it is.

One note is my baseline was with a density altitude of 3800 ft so all calculations were corrected to that DA.

 

[K4fxd]

It does need a tune to work. This is the table and info needed. any tuner can do this. I would also use the cam specs I listed above.

HP tuners IMRC/CMCV table needs to read these numbers

 

[GregO]

is it a great replacement for a gen 2 mustang? IMO yes.

Great thread Dan !
I’m learning as I go, is the 18 truck IMRC wiring connections the same as Mustang Gen 2 ?
What MAF housing diameter are you using and what air intake system ?

 

[K4fxd]

You will need to use imrc adapters. I'm using the 2018 CAI. I am considering trying the gt350 cai just to see what happens. It is sitting on a shelf in my garage.

I might try the 2017 cai but the problem becomes getting the curve to 1 to 2% so as to have creditable results

 

[K4fxd]

Here is what I think the stock center lines are




RPM Intake Exhaust Approx LSA
1000 0 5 ~106.8
1750 0 5 ~106.8
2250 -7 12 ~105.0
2750 -9 13 ~104.2
3000 -10 13 ~103.8
3500 -20 21 ~100.8
4000 -20 16 ~99.5 (tightest / highest overlap)
4750 -15 13 ~101.2
5000 0 13 ~108.8
5500 +10 13 ~113.8
6000 +12 14 ~115.0
6500 +15 14 ~116.5 (widest / lowest overlap)

 

[K4fxd]

Both cam schedules in graph form. These are optimum power schedules

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