Difficulty achieving top speed

[meltan7]

Hello to my fellow zth members and sifoos. I've got a problem here related to my car's top speed.
Here's my car specs:

Make - Proton Wira 1.5 MMC (Auto)

Mods
Powerzone camshaft
Adj. Fuel Regulator
Adj. Cam Pulley
Idirium Spark Plugs
Cap ayam plug cables
K&N drop-in air filter with CAI
4-2-1 Powerzone extractor and piping with S flow muffler
Lightened Crank Pulley

The problem is that my car has trouble going up to speed from 140km/h onwards. It could reach up to 160km/h but after a long time of flooring the accelerator pedal. On downhill, i'll be fortunate to reach 170km/h. There's loads of talk about stock cars being able to achieve top speed much easier, so i'm a bit worried bout my car's performance since i've spent so much on it, yet it can't achieve it's top speed.

I've done dyno runs when i sent the car for camshaft tuning and found that it's running rich from 1000x rpm to 3000x rpm. Could there be any problems with my fuel regulator? Apart from the mods i've listed, everything else is stock.

Another issue is concerning my gearbox. There is a lag of 1 to 1 1/2 sec lag between gear changes, and sometimes when the gear engages, there's a slight jerk as well. I'm sure there's something wrong with my gearbox, but i just don't know which part exactly.

So, i appreciate it if any members out there are kind enough to enlighten me on this particular problem.

Thanks in advance!

 

[SkYwAlKeR]

yes... running rich AFR will cause performance to decrease...

 

[contreasjun27]

yes... running rich AFR will cause performance to decrease...

agree with that...
basically your car setup is more towards pick up power bro..
so is there any how to get top speed back..
eh put in stroker kit loh hahahah or BOT

---------- Post added at 12:17 AM ---------- Previous post was at 12:15 AM ----------

btw you say jerk when you engage gear right..
might be the time for your GB bro...

 

[meltan7]

yes... running rich AFR will cause performance to decrease...

what do you suggest i do bro?

agree with that...
basically your car setup is more towards pick up power bro..
so is there any how to get top speed back..
eh put in stroker kit loh hahahah or BOT

---------- Post added at 12:17 AM ---------- Previous post was at 12:15 AM ----------

btw you say jerk when you engage gear right..
might be the time for your GB bro...

stroker kit and BOT are still out of my budget. i'm trying to extract just enough power from minimal mods.

well, if the AFR is the problem, i might get it fix 1st rather than disturb the gearbox. see how it goes. 1 problem at a time. the jerk comes and goes. not all the time.

 

[contreasjun27]

what do you suggest i do bro?



stroker kit and BOT are still out of my budget. i'm trying to extract just enough power from minimal mods.

well, if the AFR is the problem, i might get it fix 1st rather than disturb the gearbox. see how it goes. 1 problem at a time. the jerk comes and goes. not all the time.

yup last time when i drove auto also experiencing the same matter with you...
end up the condition get bad, and I'll get gear slip or the gear just don't engage

 

[12oY]

ur afpr running 2 rich may cause u problem and also ur gearbox slip also will but for auto can get 170km/h consider ok dy try check ur fuel pressure and ur gearbox

 

[SkYwAlKeR]

what do you suggest i do bro?

air + fuel = power

hence, increase air intake... open pod air filter... larger throttle body... port polish... highcams...
increase fuel pressure to compensate back the increased amount of air intake... make sure AFR is optimum... it is recommended to invest in a good engine management... for mild upgrades, safc or emanage blue would be sufficient...
next take care of ur ignition... better sparkplugs... oem cables would be sufficient if u didnt upgrade ur coil/distributor/source of ur ignition...
transmission... make sure no clutch slip... larger clutch plate or grippier racing clutch would be good... total angular momentum of ur bottom rotating mass is also important to determine how good ur acceleration or top speed...

 

[meltan7]

air + fuel = power

hence, increase air intake... open pod air filter... larger throttle body... port polish... highcams...
increase fuel pressure to compensate back the increased amount of air intake... make sure AFR is optimum... it is recommended to invest in a good engine management... for mild upgrades, safc or emanage blue would be sufficient...
next take care of ur ignition... better sparkplugs... oem cables would be sufficient if u didnt upgrade ur coil/distributor/source of ur ignition...
transmission... make sure no clutch slip... larger clutch plate or grippier racing clutch would be good... total angular momentum of ur bottom rotating mass is also important to determine how good ur acceleration or top speed...

thanks for the kind advise bro.

however, my car's an auto tranny, so i doubt i'll be switching to open pod. i was thinking of going for PnP to complement the high cam and also scouting for an e-manage.

oh, correction, my car is running lean from 1000x rpm to 3000x rpm, not rich.

 

[GoldenHawk]

Don't simply PnP bro... not everyone in M'sia can do a half-decent job :(
I think you should go for an open-pod instead. A good intake can make a world of difference :)
I was previously on a 4G15 carb, Auto, stock, on a Saga body. I could maintain 160KM/H without much problems (as long as I can stand the wind noise & revving sound-lah :P )

 

[meltan7]

yup, understood. but i thought open pod's aren't recommended for auto trannys?

 

[12oY]

if 2 lean the fuel mixture then adjust abit

 

[Shinjite]

For me, I wouldn't recommend open pod but the choice is yours to decide
PNP is a good move to compliment with your PZ cams, you can definitely hit back your top speed with it :)

As I have to in my process :D

 

[SkYwAlKeR]

a drop in filter will be sufficient for street use... highway cruising open pod feels nicer... haha...

for auto tranny, not really recommended to port ur cylinder head... a good polishing will do... over porting ur cylinder head will lose low end torque... for auto tranny, what matters most is low end torque...

highcams and emanage is a good choice... highcams recommended matspeed cams... emanage, get a good tuner to tune it...

its good to get ATF cooler as well for auto tranny cars...

 

[meltan7]

a drop in filter will be sufficient for street use... highway cruising open pod feels nicer... haha...

for auto tranny, not really recommended to port ur cylinder head... a good polishing will do... over porting ur cylinder head will lose low end torque... for auto tranny, what matters most is low end torque...

highcams and emanage is a good choice... highcams recommended matspeed cams... emanage, get a good tuner to tune it...

its good to get ATF cooler as well for auto tranny cars...

ahh.. because my car was running on open pod previously but pickup was very sluggish. so switched back to drop in filter.

well, am already running on PZ cams, so probably i'll just get an e-manage.

was thinking about an ATF cooler as well.

thanks for your help bro!

 

[Shinjite]

I am wondering, how is your dyno graph?? Power all the way to redline?? Whats the AF ratio at high end?? If too rich, more petrol gone and lose power