Hughes F1 Airgap Kit On Stock Engine

So I recently purchased an 01 1500 with the 5.2 as my first truck. I've done quite a bit of reading and decided I should probably replace the plenum gasket at some point, even though I don't think it's to bad, the truck has 145k on it so it'll need to be done eventually. I found the Hughes Engine F1 Airgap kit, and figured I might as well replace my intake with a one piece performance model. Only thing is I've also read that I really need other engine mods, which I really don't want to do even if I could afford them all, to keep low RPM power. So to get to the point, if I install the F1, with everything being factory stock, what kind of low end sacrifice am I looking at? It is a manual if that makes much difference. Thanks.

All the power you have now just driving around will now be above 3000rpm. Basically reverses the factory tq curve

Would you be able to explain how that would affect just daily driving? Thanks

Takes more throttle to do the same things as before. You'll have a lot more power on the top end but daily driving from idle to about 3000rpm it's gutless and slow.

Haha ok, so I'm guessing I don't want to go that route. Maybe just a plenum fix kit for now.

Plain plenum fix is your best bet unless you're wanting to add more parts as well. I swapped a Mopar Performance M1 manifold (similar to the airgap but little bit more low end loss bit easier to gain back as well with more potential overall, no longer made) and daily drive it. I have since added shorty headers, larger tb, tune and it's much much better. The headers made up the biggest regain for sure but it's still not quite the same as a factory engine with low end power

I put the airgap intake on my 98 sst with a 5.9 auto with no others mods. After getting my truck running properly, which had nothing to do with the airgap, i noticed a small loss of low end torque below 1800-2000rpm. After that it feels about the same as the stock manifold until about 3500 rpm, then it pulls strong up to the redline.
Because you aren't planning any additional mods, i agree with dapepper9, the stock manifold is best for you.

Do you notice any MPG increase with the F1? I'm still looking at my options here, and I'm getting that with the F1 I'm not gonna notice any performance increase unless I redline it, but it's not gonna necessarily castrate it on the low end. Honestly I'd rather put in something better while I have the intake pulled, rather than just fix it, and a noticeable MPG increase would be nice. Also eliminating the plenum gasket would be nice to. But like I said, still looking at options.

Low end loss may sound a bit worse than it really is from my description. I noticed zero difference in mpg with the mopar vs the kegger. Airgap and mopar perform vary similarly but from what I've heard from other airgap users, pretty much the acne for them. It is nice not having the plenum anymore though and it is quite fun to drive. Sound of the engine is totally different with one too

That's good to hear. I bet simply replacing the plenum will give me a boost in mileage anyway. It's a big price difference between fix or replace, so I'm still not sold either way. If anyone has any input I'd love to hear. Thanks guys.

I didn't notice any difference in mpg, but my driving style is a big part of that. Fixing the kegger will be your best option, unless you decide to do additional mods. You will notice a mpg increase with the fixed kegger. Whichever way you decide to go, do a tune up as well (plugs,wires,cap and rotor), pre cat o2 sensor can't hurt either.

I cut the runners down on my kegger and did port blending with a dremel, and I honestly couldnt be happier. The biggest difference I found was upper rpm, like highway driving is much improved, with no loss of torqe.

mopar m1 intake and 4.56 gears work great!!

I speak from experience

i would have done that hughes intake, but it didnt have a plug for a sensor? (i forget it was a few years ago)

The mopar m1 did, bolts on nice, designed by ma mopar

works great, any low end loss was gained back by the gears

but i totally understand thats probably out of the question. Best best to be cost effective is the kegger mod...most guys from what i read seem to like that

Stegs said:

mopar m1 intake and 4.56 gears work great!!

I speak from experience

i would have done that hughes intake, but it didnt have a plug for a sensor? (i forget it was a few years ago)

The mopar m1 did, bolts on nice, designed by ma mopar

works great, any low end loss was gained back by the gears

but i totally understand thats probably out of the question. Best best to be cost effective is the kegger mod...most guys from what i read seem to like that

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IAT sensor. Airgap requires moving it to the intake tube, not that it's a bad thing. Manifold kinda heat soaks it and gives reasons of 150-170 degrees regardless of conditions

The biggest thing when it comes to swapping manifolds is retuning. The low end loss is somewhat negligible , at least in a 360, after reprogramming. We picked up 20 whp and 42 wtq with no other changes other than a FRP Airgap Flash.

That's impressive! I was planning on sticking with the kegger since there are so few available intake manifolds for the Magnum heads and they all seem like they'd murder the low-end power, something I can't afford to lose much of. I might have to reconsider swapping an Airgap on...

Would you expect comparable gains/characteristics if one used the M1 instead? The M1 seems like a better overall design for a fuel-injected engine but ******* they're hard to find! I really wish someone would start making them again...

They perform virtually the same until you get into really nice stroker or boost builds

Yeret said:

That's impressive! I was planning on sticking with the kegger since there are so few available intake manifolds for the Magnum heads and they all seem like they'd murder the low-end power, something I can't afford to lose much of. I might have to reconsider swapping an Airgap on...

Would you expect comparable gains/characteristics if one used the M1 instead? The M1 seems like a better overall design for a fuel-injected engine but ******* they're hard to find! I really wish someone would start making them again...

Click to expand...

Almost identical results. The airgap makes a hair bit more tq down low , M1 makes a hair more above 5500. It's such a negligible difference that i wouldn't use one over the other.

Both work well. You'll need an updated canned tune to run either.

As long as we're talking airflow, any input on the factory heads? If one were to combine an Airgap/M1 with a beefier cam, would the heads be a significant bottleneck? Silly question I know, but I'm just curious as to how much of a bottleneck they would be. I ask simply because pretty much every head that I see which flows significantly more than OEM uses 2.02" intake valves and I'd rather stick to 1.92" for the sake of my low-end grunt. Not to mentioned they're damned expensive, LOL.

I've got OEM-spec replacements right now. They've got thicker castings between the valves to eliminate, or at least alleviate, cracking which is where the factory ones like to crack it seems. Both of mine had at least one crack in that very spot. They aren't the EQ ones though, which I've read flow slightly better than other OEM-spec replacements.

Yeret said:

As long as we're talking airflow, any input on the factory heads? If one were to combine an Airgap/M1 with a beefier cam, would the heads be a significant bottleneck? Silly question I know, but I'm just curious as to how much of a bottleneck they would be. I ask simply because pretty much every head that I see which flows significantly more than OEM uses 2.02" intake valves and I'd rather stick to 1.92" for the sake of my low-end grunt. Not to mentioned they're damned expensive, LOL.

I've got OEM-spec replacements right now. They've got thicker castings between the valves to eliminate, or at least alleviate, cracking which is where the factory ones like to crack it seems. Both of mine had at least one crack in that very spot. They aren't the EQ ones though, which I've read flow slightly better than other OEM-spec replacements.

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I wouldn't bother swapping cams without the use of aftermarket heads.

The stock heads crack, and the factory springs are terrible.
The springs can be replaced, but aftermarket springs can fatigue and break the factory 2 piece valves.
The 2 piece valves can be replaced, but then you're hundreds of dollars into factory heads that still crack, and don't flow well .
Even if you ignore the above insight and swap cams, you might pick up 10-15 whp at peak, but it comes at the expense of bottom end power. You end up with less average HP across the curve. This might work in a lightweight truck that is class-restricted to stock heads for racing, but in a heavy Ram, it is counterproductive. I never understood the logic in wanting to "sound cool" without having the power to back it up. I really try to shy away from tuning those types of setups, even if the customer says they dont give a flip about power output, they always end up disappointed anyways.

I had a customer about 18 months ago who I had this conversation with. Big cam, stock heads, full bolt ons. He was insistent it would make big power. I had retuned it from another popular SCT tuning vendor and he said it ran great after I did my thing. Get to the dyno.....it made 261 whp. He was furious, but I warned him ahead of time that without aftermarket heads, or a ton of work into the OEM heads, that's about as far as it would go. Had he bolted on a set of aftermarket heads- any aftermarket head- he would have made 320+ wheel without issue.

The valve size is far less of an issue than camshaft selection.