Atom 3 Intake Hose Upgrade

[timcking]

I've wanted to replace the OEM neoprene spiral-wire intake hose for some time. I was perusing the Pegasus Racing website and stumbled on a 180 degree 3" ID silicone hose (link below). After doing some measuring on the car, decided to order one and try fitting it.

https://www.pegasusautoracing.com/pr...sp?RecID=11892

Upon receiving it, I trimmed 3/4" off of the throttle body end. It's very close to a perfect fit and being flexible allows it to fit quite well.

This should improve both the flow and durability. I used the OEM hose clamps, and since the fiberglass outlet from the filter housing is somewhat smaller, I put duct tape on that end wrapped around half on the outside and inside. It reduced the ID and provided a better seal on the fiberglass.

[timcking]

I've wanted to replace the OEM neoprene spiral-wire intake hose for some time. I was perusing the Pegasus Racing website and stumbled on a 180 degree 3" ID silicone hose (link below). After doing some measuring on the car, decided to order one and try fitting it.

https://www.pegasusautoracing.com/pr...sp?RecID=11892

Upon receiving it, I trimmed 3/4" off of the throttle body end. It's very close to a perfect fit and being flexible allows it to fit quite well.

This should improve both the flow and durability. I used the OEM hose clamps, and since the fiberglass outlet from the filter housing is somewhat smaller, I put duct tape on that end wrapped around half on the outside and inside. It reduced the ID and provided a better seal on the fiberglass.

Finally got a chance to drive my Atom with the 3" ID neoprene hose. It's noticeably different. I can't tell by the-seat-of-the-pants, but I'm not disappointed.

[timcking]

Just an FYI to Atom 3 owners. Following the initial installation described above, I made a further modification to the intake hose. The silicon 3" ID intake hose I sourced from Pegasus Racing has an ID almost 1/4" larger that the OEM spiral-wound hose. Upon further investigation I noticed that the intake plenum box outlet was tapered down to fit the OEM hose. By cutting off approximately 3/4" off the end of the outlet tube, I was able to obtain a 3" OD. This facilitated a perfect fit with the retrofitted silicon hose.

Since now the hose had to be longer, I used a short section of straight hose combined with a coupler to extend the 180 degree hose. At the same time I sealed the airbox in the plenum.

I briefly ran my AA3 for the first time a few weeks ago in an auto-x. The car is transformed. I'd conservatively estimate 20-25% more power once past 6,500 rpm. When I received the car in 2009 it dyno'd at 202 rwhp. In order to pass smog, I had a California Hondata tech (Warren Mak) retrofit it with the necessary components and tune it for 91 octane premium. It subsequently dyno'd at 227 rwhp. I haven't put it on a dyno since the intake system upgrade, but seat-of-the-pants I'd estimate it at around 250 rwhp. It's that different. And, all together the intake revision is about a $100 expense.

I realize this is difficult to believe, but aside from the 1) slightly larger radius of the inlet tube 180 degree bend, 2) smoother tube interior wall, 3) larger diameter (of both the tube and plenum outlet); the sealing of the plenum and the hose configuration may have hit a "sweet spot" causing a pressure wave resonance supercharging the inlet system. It's still hard for me to believe this minor modification produced the results I've seen. It's similar to taking a normal street engine and thoroughly modifying it to its maximum. It's that different.

I don't know if this will produce similar results on other AA3s, but I don't see why it wouldn't.Atom 3in revised intake.jpg

[2/3rdsCobra]

Snipped a bit;

I briefly ran my AA3 for the first time a few weeks ago in an auto-x. The car is transformed. I'd conservatively estimate 20-25% more power once past 6,500 rpm. When I received the car in 2009 it dyno'd at 202 rwhp. In order to pass smog, I had a California Hondata tech (Warren Mack) retrofit it with the necessary components and tune it for 91 octane premium. It subsequently dyno'd at 227 rwhp. I haven't put it on a dyno since the intake system upgrade, but seat-of-the-pants I'd estimate it at around 250 rwhp. It's that different.

I call BS..... on the Auto-X attendance, lol. Vids or it didn't happen .

[cvjoint]

The OEM design is terrible, this much is true. Jagged brake ducting hose bent 180* is not going to perform great no matter what. There are two builds making around 300 whp that got ~15whp by going with a straight intake pulling air from the side of the car.

However, I don't think you can see those gains without going with a straight pipe and for a 227whp engine. You might see 5whp gain. Supercharging is a whole nother world and you can't get there by ramming air into the manifold no matter how hard you try. If it really did add 25whp you would run really lean and need a tune to run safely. The GT3 got 10hp more by adding ram air and that's a 500hp motor and at speeds that Atoms cannot achieve: https://www.motortrend.com/news/2018...t-look-review/. Besides, the basic snorkel design is unchanged with the modification and you still have the 180 degree bend. 250whp is about what the HPD motor makes. You are saying that you can achieve that by smoothing out a tube where Ariel needed a $20K motor.

Great mod for $100 bucks though!

[timcking]

I know it's hard to believe. Yes, as I stated I have a Hondata K-Pro ECU tuned. I posted this for an FYI. It's your loss if you don't see for yourself.

[cvjoint]

I know it's hard to believe. Yes, as I stated I have a Hondata K-Pro ECU tuned. I posted this for an FYI. It's your loss if you don't see for yourself.

Huh? Why would it be hard to believe you are tuned with Hondata? It's the cheapest most abundant solution for Honda engines. Heck, the Atoms even come stock tuned with Hondata.

What I doubt is that your mod got you from 227whp to 250whp. If you have a $100 mod that's the equivalent of thousands of dollars of mods in terms of output you should dyno before and after to prove it. I've seen the same car on two different dynopacks yield 20whp difference so 227whp doesn't mean anything to me. If you dyno back to back, with and without the mod, and we see on the same dyno that you gain over 20whp that might convince someone.

[jeff8407]

I can actually believe the upgrade. My airbox had a round fiberglass outlet that was just under 2" in diameter (I.D.)--with that type of restriction I can certainly see the HP gains being thrown about. I avoided the whole issue by going to an RBC intake and a side intake just forward of the Left Rear tire. The length is a bit short for a NA Honda engine (the Honda K-series engines prefer a long tube intake of about 3" in diameter....), but it works and is much better than the stock intake tract.

[McFred]

I'm pretty sure a before and after dyno would eliminate any confusion or difference of opinion on power output, but historically, a 2.0 K-series will not put 250hp to the wheels, corrected, without cams, nice exhaust manifold and more RPMs.

I've had a bunch of work done on my k-powered AA2 and make only 12 more whp than your butt dyno's claim. I'll say I did pick up a few whp on changing to a 3" intake/cone filter over the original Brammo monstrosity (Factory K20A K-Pro re-tuned), but it was power at the last 500-700 rpm and not 25whp.

Either way timcking, I'm glad you're out enjoying your Atom in the way it should be: racing. Thank you for sharing.