: Cold Air Intake? Bypass Valve? Both?
Jan 15th, 2008, 04:36 PM
Newbie poster and first time modder here (very inexperienced and not as knowledgeable as i want to be). Wondering if i can get an opinion from some of you.
I have an 03 MCS and i am about to do my first couple mods. I have a Helix 17% pulley on a DHL truck as i write this. Everyone seems to agree this is a geat place to start.
I also have been given the chance to purchase a bypass valve through a group buy at a good price, and it was recommended that i do this mod too. this is where i start to get conflicting information.
Some say the bypass valve is a worth while addtion, some say the only reason to do it is if my current one is broken.:puzzled:
I am definitely doing the pulley, and based on that here are my questions -
1. Would you do a new bypass valve at all?
2. If you have done it, what is your experience?
3. If it was you, would you take advantage of a group buy and do the bypass valve, or would you take that money and do a CAI first? ( i cant do both the BPV and CAI right now due to lack of funds so i have to pick one).
I look forward to your responses.
Jan 16th, 2008, 04:16 PM
Well, you pose a very good mod question. I have done both on an '04 MCS. It's a "dollars vs. results" thing in my book. But then again, you're reading words written by someone who went the JCW route rather than aftermarket!
Some '03 and '04 MCSs came from the factory with with the dreaded "Yo-Yo", a power oscillation under WOT between about 3,000 & 4,000 rpms. The Yo-Yo was a result of a bad sensor-dampening algorithm causing oscillating vacuum levels to the supercharger bypass valve. This caused the BPV to open and close repeatedly under WOT, which produced a bit of a "bucking" effect...thus "Yo-Yo".
The DT-BPVs have a stiffer diaphragm spring installed to dampen the oscillations. As a side effect, they add a certain amount of a "binary feel" to the throttle...less "in-between" feel in throttle transitions, more of an on/off feel. Some folks like this, some don't. If you will be doing some HPDEs, you may not like the binary feel.
Additionally, some number of BPVs were not closing completely as adjusted by the supplier to the MINI production line. While *slightly* mis-adjusted, they certainly did not allow a whole bunch of boost to escape, but perhaps a (technically) measurable amount.
All the DT-BPVs have bee readjusted to eliminate boost escape due to mis-adjustment.
I'm not sure that a significant performance difference can actually be had by installing a CAI alone. However, I think it could be a technically beneficial mod to make in concert with more significant changes. Traditionally, CAIs have been popular with pulley modifications, and I think it probably makes sense as long as you don't spend $500 on a JCW model (:rolleyes:) like I did.
If you don't have the "Yo-Yo", you may not find the BPV to make a big difference. It also requires some fairly adept engine-plumbing work to remove and replace. Not impossible for a shade-tree mechanic...but keep the beer locked-up until the job is done!
However, as long as you don't have the "Yo-Yo", you might want to adjust your own BPV and save some money. Instructions can be found in the "Yo-Yo Chronicals" on NAM.
And if you are looking for a more binary, "instant-on" feel to the supercharger's boost, you may want to perform the $8 "Vacuum Gain System" mod also detailed on NAM.
And, finally, if you are adding a pulley, it is probably technically worth it to do the CAI. A number of kits are available; Alta makes a popular one.
Note that neither the BPV, VGS, nor the CAI will make a "seat-of-the-pants" difference like the pulley will. IMHO, the CAI will help to compliment the pulley change, though.
Jan 16th, 2008, 04:37 PM
I did the Alta CAI and the Alta 17% at the same time and WOW...not only did my butt fancy the mods, but it was VERY pleasing to my ears....a lot more race car sounding... Shortly after i did the DT Bypass valve...it took me about 2 hours doing it at night with a small pen lamp and a halogen lamp. I found that you'll need some patience in manuevering the horn off (you'll see what i mean if you get it) and that unless you have the right tool (luckly i did) putting the MINI hose clamps on can be very annoying (even with the right tool it was annoying) so get yourself some hose clamps from your hardware store. oh and You'll need to remove the tube that connects your CAI to your throttle body to get to your BPV so doing the CAI and the BPV at the same time wouldn;t be a bad idea.
The BPV btw give more kick earlier
Personally I'm happy with the steps that i Took, and would recomend the same, CAI and Pulley... and then BPV.
Jan 16th, 2008, 05:53 PM
Vanno and Theo,
I am pleaed to say i have made my decision and now i just have to get it done.
But the parts are on their way!!
1. Helix 17% pulley
3. maybe later in the summe, the BPV.
I appreciate you thoughtful responses. Both very helpful
Jan 16th, 2008, 06:18 PM
Go to MOT (www.MINIsONTOP.com) to check out mods that other people have and get their input...I'm sure some would even let you try their MINIs or atleast go for a spin,...Last year I was checking out people's Exhausts...I felt like a dog as i closely inspected the rear of each S that i could find
Also they give out a lot of freebies and prizes since many manufacturers are there
Jan 16th, 2008, 06:23 PM
i would certainly love to do that ths year.
freebies are always a good idea, in fact FREE happens to be my favorite flavor!
Have you been more than once? Did you stay or go for the day?
Jan 16th, 2008, 07:09 PM
Last year was my first and I'm going againn this year...last year I Went over with a group from WNY on thrusday and Stayed till Sunday...One day is Not enough
Jan 16th, 2008, 07:17 PM
check out the festivities here:
And, of course, post here:
Jan 16th, 2008, 08:24 PM
MOT looks like a great time indeed. I did a small gathering this past december for the MAKE A WISH foundation in Rhode Island. Good cause, a real blast and that was only 20 or so MINIS. t must be a real rush with all of those people coming from so far in those numbers. I really hope we can do it.
Thanks for the links and info you guys.:D
P.S. I am new to the whole forum world, is this what is considered off-topic now? If so I apologize.
Jan 16th, 2008, 08:29 PM
heh. If we worried about "off-topic" here, 60% of the posts would have to go.:D
Jan 17th, 2008, 04:15 AM
yeah it still relates, but thats a good off topic topic anyways
Jan 24th, 2008, 05:03 PM
another good addition to the mods you have selected is a colder range spark plug. I use Denso Iridium IK22's with good results. I swap them out every 40,000 miles and check the torque(22-24 ft lbs.) OFTEN, as all plugs in these cars seem to have a tendency to loosen. let us know what you think after you've done the mods and good luck. Jock