New member here (great forum!)

I recently had a 16% m7 pulley/belt installed by the awesome guys at MACH V in Northern Virginia (great guys to take your mini to if you're nearby.) I also put a drop-in K&N filter but otherwise, my 2005 MCS is completely stock. Let me say this: I LOVE the added hp, especially up top but I have noticed the following:

1)The hp curve flattens out between about 3800 on up to about 5100rpm when you can feel a real kick from 5200 on to redline. Is this common with the aforementioned setup? I've read a few things about belts slipping. I had the JCW-spec pulley belt installed


2)I've also been considering a CAI but haven't been 100% convinced they do anything but add intake noise. I've gotten my "hey, look at me" outta my system a few years ago with sportbikes so I'm trying to keep it low profile in the twisties. Would a CAI smooth the curve out a little? I'm thinking about a JCW intake based on what I've read and seen here and other sites.

3) I've also considered getting the ecu tuned and looking for someone on the east coast (pref dc area.) Any ideas? It was recommended by Dan at MACH V over canned tunes or piggy-backs. I was thinking this might contribute to a smoother curve.

4) Would exhaust help smooth things out? I've been considering a resonator-delete setup...

thanks for an awesome resource for mini owners

-kim

 

did you go with colder plugs in addition to the pulley? just to be safe. so how long ago did you have it installed? the computer could still be learning .

 

Installed yesterday, it had the stock plugs in it and were replaced with the same heat-range. Dan at MACH V recommended that stock heat would work for cars modded up to +60-70hp.

 

LOL

You right about the CAI, mostly better noise and aesthetically pleasing, plus K&N panel filter works fine. Resonator delete mostly a bit louder and pronounced burble. Although, one ball will do the same and lose about 30lbs. But yes a step colder plugs like Brisk or Iridiums IX should be done, also make sure you use at least 93 Octane. Call M7 regarding correct belt size and part No. And if that is all the mods you have planned, then a custom dyno tune will help your situation. If you still plan for more mods wait on tune till your mods are complete. (or at least think you are done) and then tune it.

 

Just scheduled a dyno at MACH V to see if I'm just being particular about the curve...

 

THe JCW belt is wrong for a 15% pulley, so it is going to be too big for a 16% pulley. You will need a smaller belt, I just don't know the part number off hand, but if you search around it can be found.

 

Get colder plugs!! Cheap safety.

Are you sure the JCW belt is not slipping with the 16% pulley?

Most people (myself included) here are using a much shorter belt then then JCW for even 15% pulleys.

I have an Alta v2 15%, one-ball (i assume what you mean by resonator delete) and a modded stock airbox with an Alta drop in filter, and Brisk colder plugs.

My powerband is very linear, no real flat spots as you mention.

 

Your flat spot, if not caused by a slipping belt, could be removed by a tune.
Your may also be noticing it now, it was most likely always there, because of the new pulley.

My car had a flat spot just like yours. Got a tune, no more flat spot.
Get the right belt, colder plugs and a tune.

Hope this helps...

 

Use a Gates 060535...use OEM NGK BKR7EQUP plugs...get a tune at Behe Performance(link in my sig)

 

quick update:

Talked to Peter at M7 and he assured me of the following:


1.The JCW belt is correct for an M7 16% pulley

2.The stock heat-range plug is appropriate for low-level mods (pulley, cai, exhaust) Just to repeat, this is exactly what Dan at Mach V told me (I shoulda listened, lol)

3. the curve I described is symptomatic of the programming and can be improved with a proper tune.

I still have a date with the dyno which should show if I'm just being persnickety about power delivery

Some people have PMed me about tuning options on the east coast, thank you!

will return with a dyno chart...

 

Just a note on heat range for spark plugs: If you go with too COLD a plug, you may end up fouling the plugs, since they will not heat up enough under normal driving to burn off carbon deposits. We installed Denso Iridium plugs in rawcapture's car, in the stock heat range. Iridiums generate a smaller, hotter spark than conventional or platinum plugs, so they're able to work well in difficult mixture conditions (like higher boost pressure), even in the stock heat range.

My rule of thumb, which has served me well for many years, is to go one range colder per additional 75hp. A pulley is a great mod, but it doesn't add THAT much power. Hence the stock heat range recommendation.

--Dan
Mach V

 

if only, lol. I'm not complainin'. The trip to manassas via henderson/old yates just got interesting

 

Seriously . It is probably not what it is causing your flat spot, but you really believe that a belt made for an 11.something % reduction is going to work on a pulley that is over 4% smaller? This has been covered in the forum many times before. The OEM JCW pulley is to big for a 15% pulley and would fit even looser on a 16%. Partsman gave you some good advice. Check this out:

https://www.northamericanmotoring.co...463-post4.html

 

The Denso plugs in your car have a fine center electrode that is not long lived. I've seen them used up in less than 10k miles and they seldom last to 15k. Also, those plugs are notorious for backing out, check the torque regularly.

Below is a photo of a JCW belt on a 15% reduction pulley (larger pulley than yours), notice no hole on the stop strap can be seen above the bracket. If after a day of use, you can't see at least a partial hole showing, your belt is too long.


This is the hole in the strap that should be seen above the bracket.

 

Too funny, I just posted the link to those same pictures .

 

guys, thanks for the input but I have to ask:

1. are there any specs available that show proper tension for 0% pulley and oem belt?

2. Are there any tension measurements that have been done that show that the JCW belt with 15/16% pulley does not provide recommended tension?

3. should these measurements, if available to be made, be made hot or cold?

edit: Just checked the tensioner and, after 250 miles from install, I'm showing 1/2 of this hole on my 2005 MCSa with 16% and JCW belt in a cold motor...

 

where is RMW at? i'm sure he will get things sorted out and make this tune go the right direction....................i don't even know the guy but he is a legend on these forums

 

6 posts and we discover it's an automatic. This flat spot probably has more to do with gearing characteristics.

 

Sorry I didnt mention that earlier, I only recently discovered that is is widely thought that only manuals are being modded. Are the fuel maps for for manual different from auto? Maybe a stupid question as I assumed


Any additional thoughts on the tensioner?

 

Correction.......
He meant to say 'too long', not too short'.

The JCW belt is designed for the 11.45% JCW pulley. It will work for a 15%, or even a 16% pulley, but it may also slip. If not today, then tomorrow.

The consensus is to get the Napa/Gates 060535 belt, it is a little shorter than the JCW belt and will provide some hole showing at the tensioner.

All belts will slightly stretch (i.e. get longer) over time, when your belt gets to the point of showing no hole at the tensioner, it is time to change it as it will likely already be slipping under load.

 

should this "measurement" be taken hot, cold, with/without the engine running?

I looked at the tensioner while (someone else was)revving and the spring expanded to the point where no hole was showing. Once the motor was off, the tensioner went back to its previous position of about 1/2 a hole showing.

Has anyone observed the range of movement in their tensioner wile actually OPERATING the vehicle?

ANyone here with a non-pullied car care to chime in with the position of this tensioner hole?

 

If you already have the 16% pulley installed and you are showing half a hole with the engine off, hot or cold, then there is no urgent need to change your belt. That would be a bit surprising that you have that much hole with a 16% and a JCW belt, but not impossible. Next time you change though, I would go for the 060535 belt. It will be snug to get on, but it will NOT slip.

 

here it is after a little sprint in 97degF temp:

 

Ok then, unless your belt is cracked or frayed or otherwise showing signs of wear, there is no need to replace it as it is not too long for your present pulley size.

 

One thing I havent seen mentioned in this thread is that when installing aftermarket plugs check them every couple of thousand miles since the tend to come loose.........I had Denso's installed and was never told to check the plugs....well I sold a car to a friend and one day two plugs shot out of the head stripping the threads.........cost him $$.