MCX turbo how much boost with stock fuel pump

[snowy1]

I just installed my mcx kit on my nytro, and was told I could only run 15 lbs with the stock fuel pump, can any body tell me for sure what the stock fuel pump will handle. I was under the impression this kit came with everything to run up to 18 lbs. I guess that has changed I now have to pay extra for the additional fuel pump, any body recieve there kit with the extra pump, and are they running just one bigger pump or the stocker and an extra.

 

[rxrider]

On their site they say that the stock fuel system and injectors can handle up to 275 HP

http://www.mcx.se/upload/pdf/yha-Nyt-08-info.pdf

With the stock turbo kit the sled runs at about 14 lbs making 235 HP, so 275 HP would be at about 18 lbs of boost.

 

[snowy1]

On their site they say that the stock fuel system and injectors can handle up to 275 HP

http://www.mcx.se/upload/pdf/yha-Nyt-08-info.pdf

With the stock turbo kit the sled runs at about 14 lbs making 235 HP, so 275 HP would be at about 18 lbs of boost.

that was my undersatanding but my dealer says you need additional pump to run over 15 lbs. my understanding is the earleir kits came with additional pump for 18 lbs. but know they don,t you have to pay extra, of coarse I wasn,t aware of that when I ordered the kit.

 

[PwdrNut]

The first few kits came with a seperate pump. The stock pump was removed and the other pump installed. It is an easier install without the replacement pump.
I believe the turbo is out of it's efficiency at 18 PSI, so you wouldn't want to run it that high anyway.

 

[rxrider]

At 18 lbs it is in the upper region of the map, but not out of efficiency just yet. Any more than 18 will be tho. At 22 lbs it will reach it's HP limit. Even tho it is capable of 25 lbs it will not make any more HP past 22 lbs, only more heat and detonation trouble.

 

[snowy1]

I am not concerned with running 18 lbs. my concern is at 14 lbs I am running 16,s on my a/f gauge I wonder if the other pump is needed to supply enough fuel under boost, I still don,t think I should be running that lean even it is only in the mid range, on these turboe,s thats were you run most of the time. I haven,t been able to run it wot yet to see what the readings are there.

 

[rxrider]

Are you 100 % positive that you have hooked up the injectors in the intercooler plenum correctly when it comes to power and fuel? How is your WOT AFRs if your going down on boost? Try the lowest boost possible and check your WOT readings, if it's still lean something is not right.

I have seen an Apex going into detonation because of an electrical miswire to the injectors in the plenum. It ran 12 lbs on stock fuel delivery, result was ugly.

 

[snowy1]

I have not been able to try it wot yet, thats the first thing I thought about so I called the dealer to see what he thought/ he told me they are seeing that in the mid on all of them, so I am assuming the wiring is right but I have not ruled it out. what kind of a/f readings did you see on the apex I would think they would be alittle higher if the secondary injectors where not getting any fuel. kind of scared of going wot until I am sure of whats going on.

 

[rxrider]

Sorry, my friend did not have a WBO2 on board and detoantion took out the rings and pistons at first WOT on his sled. He found the electrical wire to the MCX injectors was not connected, :-(

 

[TBird]

what kind of a/f readings did you see on the apex quote]

I see the following numbers on an Apex MCX.
1. Cruising, 7000rpm, no boost, AFR: 14,4/1
2. Cruising, 7000rpm, ~3PSI, AFR: 13,0/1
3. Acc, 9000rpm, ~7PSI, AFR: 12,5/1
4. WOT, 10200rpm, 12PSI, AFR: 12,0/1

 

[rxrider]

Looking good TBird spot on

 

[snowy1]

well Ihave gone through everything and nothing wrong with the install, so I will put it back together and go run it and see how it works. thanks everybody

 

[TBird]

Looking good TBird spot on

I really like the MCX display for it's logging and tuning capabilities

 

[snowy1]

ok went out today and was able to run it wot up hill, 11.5,s wot wide band is working fine, 11.5 to 12 everywhere except between 3-5 lbs of boost then its 16,s and spits and pops another indication of being lean, this is with out a doubt the best sled I have owned, the mcx turbo works great except the lean spot, this has got to be fixed. mine must be worse than others because this thing will not beat anything out of the hole with the lean spot,no matter how I work the throttle its there, once it gets paste that point it runs great.