MCX 180 Update

Shermanator · Dec 25, 2009

As far as I know there have been no issues with these kits but I just wanted to point out a possible boost issue. Its not a bad thing! Appearently us "do it yourselfers" putting these kits in have been wondering what the factory setting for the boost was, we all assume the 6 psi that is advertised. However, one guy checked his once installed and found out it was at 12!! Needless to say a wee bit high and not so good for the motor if not corrected.
So, after my initial test, which rocked, I did what Sly suggested and broke down and installed a boost guage. With my sled over revving it too was thought that it was overboosted. Not so! We ripped up Sugarloaf yesterday and the most I got out of the turbo was 8 psi, although most of the time I only needed 5-6, what a sled! So, I'll crank the rod out one more turn and see where its at then but the performance was again nothing short of stellar. One of the guys we were riding with has a 1200 Cat, his only comment when he got back was "Wow!!"............Sherm

**One other tidbit of info, at the end of the day we compared fuel mileage. Bruce had the stock Nytro, 153", he had 2 bars left on his fuel gauge. The turbo, 2 bars left as well!**

tool_man · Dec 25, 2009

I am still waiting on my kit, but was able to get a copy of the install manual to be ready. And it states the boost is not preset to 6 lbs, and to test and set up prior to riding hard.....could have been costly! Good to know the fuel won't be a major issue too!

MERRY CHRISTMAS.......wish I got my BOOST present....

Shermanator · Dec 25, 2009

I didn't see where it said it wasn't set at the factory in my manual, it just said "The recommend turbo pressure is 40 kPa. (6psi)". I guess us newbies would assume if the kit came out as 6 psi it would only make sense to set it at that at the factory, but of course make sure its that once out in the field. They also say to test it while in the shop which I did and it only came out to 5 psi, yet pulling hills it got as high as 8 psi, so the shop test never even came close! Error on the side of caution. I did check my plugs though and they looked pretty good but I'm still going to turn the rod out a turn or so........Sherm

TBird · Dec 26, 2009

Hi guys, i'm glad you are pleased with your MCX 180 sleds, i just want to explain the litte i know about MCX turbo kit's, it may clarify some about why you may see higher boost pressure then expected when looking on an boost meter.
What you must understand is that MCX turbo kit's adjust to keep absolute pressure, target pressure if you will.
Absolute pressure is boost pressure + atmospheric pressure.
MCX180 kit's is set to ~20.5psi absolute pressure, so if you are @ sea level you will see ~6psi of boost pressure.
When climbing to higher altitude you will see higher boost levels, for every 1000 feet atmospheric pressure decreases 4%.
When driving @ 3000 feet atmospheric pressure decreasesed 12% = 1.74psi, MCX turbo kit adjusts boost pressure to keep absolute pressure @ 20.5psi which means boost pressure is 1.74psi higher => ~6 + 1.74 = ~7,74psi a.s.o.
This is why a naturally apsirated engine can't stand a chance because it lost 12% @ 3000 feet of it's power @ sea level, an NA engine producing 180hp @ sea level have ~158hp @ 3000 feet, while an MCX180 still have >180hp.
Don't read the examples i given as an absolute truth

more as an guidence for better understanding why boost level rise with altitude.

tool_man · Dec 26, 2009

So is 6 psi at sea level max boost that is safe on premium fuel? Higher boost requires higher octane fuel, or head shim - correct?

M5- · Dec 26, 2009

tool_man said:
So is 6 psi at sea level max boost that is safe on premium fuel? Higher boost requires higher octane fuel, or head shim - correct?

Correct.

With the MCX kits boost + elevation + stock compression ratio are all factored in to create a constant. As elevation changes so does boost in order to maintain that same constant so you would see radically different boost levels at sea level vs say 13,000 ft. The compresssion ratio really doesn't affect anything its just the limiting factor in the equation for pump fuel.

M5

Shermanator · Dec 26, 2009

Thanks TBird, that sort of clears it up? Soooooooo, if I was reading a max of 7-8 psi and we were around 6500', does that mean the turbo is set up properly, because that would translate to approx. 6 psi at sea level. So how are you supposed to set it up so you don't exceed that "recommended" 6 psi? Sherm

TBird · Dec 26, 2009

Set it up?
They are set up from MCX, you shouldn't have to touch it!
If there's something wrong within the system, for example the spring in the wastegate is wrong, or something blocks the wastegate to move freely it's an risk that boost gets to high. You notice that if it starts to over rev everytime you hit the throttle.
I wouldn't drive my sled without boost and lambda meters, but you must understand that for ex. 8psi @ 6500 feet isn't wrong, it's infact almost perfect!

SLY · Dec 26, 2009

The MCX 180 kit uses the stock fuel system. My understanding is that it can only supply fenough fuel to support 6lbs of boost, therefore over 6lbs would not get enough fuel. I could be wrong, but until there is some clarification I would keep it at 6. Happy boosting.....boost rocks

julio · Dec 26, 2009

SLY said:
The MCX 180 kit uses the stock fuel system. My understanding is that it can only supply fenough fuel to support 6lbs of boost, therefore over 6lbs would not get enough fuel. I could be wrong, but until there is some clarification I would keep it at 6. Happy boosting.....boost rocks

the stock system with a presure line to it will run up to 6 lbs ,I think ,but the stock system with a fuel controller will run up to 18 lbs before running out of fuel. At least on an apex. the nytro may be different but cant believe yamy would change how they do things that much. julio

TBird · Dec 26, 2009

You are so right, it has enough fuel for +180hp. which is 6psi of boost @ sea level!
And as you climb MCX IIC adjust boost to keep absolute pressure constant to give you 180hp @ any altitude!
Don't lock on the boost alone, think absolute pressure equals HP, it have enough fuel for +180hp, not 6psi boost.
I don't really understand why you are so sceptical, i have had the same system on my Apex for years, because i drive an MCX.

EZmoney · Dec 26, 2009

Sly.. i think the stock fuel system is safe to 12psi you should be fine. Run it the way its sent from mcx. You will see spikes on the road going up the mountain when you hammer on it at lower elevations. Although the boost spike will settle quick and wont cause damage.

julio · Dec 26, 2009

Shermanator said:
I didn't see where it said it wasn't set at the factory in my manual, it just said "The recommend turbo pressure is 40 kPa. (6psi)". I guess us newbies would assume if the kit came out as 6 psi it would only make sense to set it at that at the factory, but of course make sure its that once out in the field. They also say to test it while in the shop which I did and it only came out to 5 psi, yet pulling hills it got as high as 8 psi, so the shop test never even came close! Error on the side of caution. I did check my plugs though and they looked pretty good but I'm still going to turn the rod out a turn or so........Sherm

from experience the kit may need some adjustment. My mcx 290 needed some adjustment to get the boost to where it was supposed to be. So did a friend of mines who had his kit installed at a shop, first day out it was makeing 20lbs at half throttle. So find out what you should have and check it to be sure.

Shermanator · Dec 26, 2009

And I thought this was going to be an easy process! I also assumed it would be set from the factory and, with the altitude compensator that is hooked up to the turbo it would take care of any elevation problems and the boost changing. I guess because I was only getting the 5 psi at home in the garage and then up as high as 8 on the pulls at elevation, something wasn't working just right in system or the boost wasn't adjusted properly. Until more guys get this particular unit out in the field it may take a bit to figure out just what might need adjusting but, I certainly don't want to be running it to lean...Sherm

TBird · Dec 26, 2009

I made an litte document you can look @ to figure out expected boost levels @ diffrent altitudes!

SLY · Dec 26, 2009

TBird said:
You are so right, it has enough fuel for +180hp. which is 6psi of boost @ sea level!
And as you climb MCX IIC adjust boost to keep absolute pressure constant to give you 180hp @ any altitude!
Don't lock on the boost alone, think absolute pressure equals HP, it have enough fuel for +180hp, not 6psi boost.
I don't really understand why you are so sceptical, i have had the same system on my Apex for years, because i drive an MCX.

Not really sceptical on anything MCX builds, I have been installing and selling them since '05. Just haven't been able to keep a 180 around long enough to play with and don't want to see anyone have problems. I currently run a 270 kit on my own sled and use a manual controller to keep the boost level at between 15-17. I guess I could probably run a little higher as well at 6-8k ft but no-one wants to lose the reliability of what are arguably the best kits on the snow

HYFLYR · Dec 26, 2009

EZmoney said:
Sly.. i think the stock fuel system is safe to 12psi you should be fine. Run it the way its sent from mcx. You will see spikes on the road going up the mountain when you hammer on it at lower elevations. Although the boost spike will settle quick and wont cause damage.

The stock system cannot handle 12lbs of boost or maintain it especially at sea level. Nytro fuel pumps are good to about 10lbs and even after a long run will start to lose fuel pressure. Ive set up many sleds(turbo and supers) and none can keep a/f under 13 above 10lbs at sea level.

EZmoney · Dec 26, 2009

HYFLYR said:
The stock system cannot handle 12lbs of boost or maintain it especially at sea level. Nytro fuel pumps are good to about 10lbs and even after a long run will start to lose fuel pressure. Ive set up many sleds(turbo and supers) and none can keep a/f under 13 above 10lbs at sea level.

Sorry... thought we were talking apex for some reason. thanks for catching my mistake hyfyr:beer;

TBird · Dec 26, 2009

lol, if someone wants to adjust boost manually i sure can't stop them, i can't see why tho, MCX have built a totally computer managed system that's tested @ every possible altitude, it works!
I don't have all the data, for ex. @ which altitude the turbo charger is maxed out, where it can't keep absolute pressure any longer, but it's atleast 8000 feet higher then a 270 kit if calculating on it.
MCX 180 is a sweet kit, and have apparantly a very advanced / intelligent system controlling boost and fuel that competition doesn't have to my knowledge, but i can assure all and everyone that it's been THOROUGHLY tested in every possible altitude.
And their altitude compensating boost system is far from new, i've had it in my Apex several years, so i wonder why everyone thinks it's an issue when they read higher boost @ altitude then on sea level, it's nothing new, i find it a little strange to hear experienced tuners having hard to comprehend "absolute pressure = atmospheric + boost pressure" piece of cake

.

And if someone have further question about how MCX kit's work i suggest contacting an MCX dealer, and if they don't know they should find out.

j_w10 · Dec 26, 2009

So I have too agree with hiflyer, from all that I have read the stock pump can only handle around the 10psi, mark and if you ramp up the presure the fuel injectors cycle out around that 14psi mark.

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