CC6 SBC uncompressed linux kernel

Settings : CC6 SBC imx6 quad booting form an external EIM NOR flash 16bits on our custom board.
PC setting done from:

Hello, currently i am focussing about kernel boot time, i’ve customised u-boot to have lighter software (and faster mecpy) and it’s ok from this point of view.

I’m facing trouble to build/use an uncompressed kernel image with uboot.

Currently i do
$bitbake linux-dey -c menuconfig
for configuring kernel setting and after that
$bitbake linux-dey
to build kernel (with LZO compression setting)
After a while, i have in tmp/work/ccimx6sbc-dey-linux-gnueabi/linux-dey/3.10-r0/git/arch/arm/boot
followings file
zImage (size 2 465 816 bytes)
uImage (size 2 465 880 bytes)
Image (size 4 480 736 bytes)

Downloading uImage on Uboot is OK and kernel is running fine.
If i do
uboot-mkimage -A arm -O linux -T kernel -C none -a 0x10800000 -e 0x10808000 -n Linux --base=0x10800000 -d /home/eric/muxlog/tmp/work/ccimx6sbc-dey-linux-gnueabi/linux-dey/3.10-r0/git/arch/arm/boot/Image ./uImageNozip
uboot-mkimage -A arm -O linux -T kernel -C none -a 0x10800000 -e 0x10800000 -n Linux --base=0x10800000 -d /home/eric/muxlog/tmp/work/ccimx6sbc-dey-linux-gnueabi/linux-dey/3.10-r0/git/arch/arm/boot/Image ./uImageNozip

Produced file (uImageNozip) dont boot on the board.

My question is :
Does anyone can tell me how i can produce an uncompressed kernel that work from this Image file ?

Why i do this and focus on boot time ?
Simple currently Uboot prompt come ater 140ms power supply, copying 2.4MB from flash to RAM use 160ms and kernel decompression (LZO) take 520ms before first kernel prompt (Booting Linux).
Total before kernel run time : 960ms

If i achieve to run an uncompressed kernel, first kernel prompt will be occurs theorically 140ms+320ms (assuming that Image is two time bigger than uImage)
Total before kernel run time : 460ms (that’s fine our goal is to boot in lesser than 500ms.

Thanks for your help and please excuse my bad english skill, it’s not my native language.