red hot exhaust manifold

[wira hitam]

recently i overhauled my 4g93t gsr rs. I replace a few thing
1. rebore from 81.0 to 81.5,
2. my standard piston ratio is 9.1:1 for the new piston is 8.9:1.
3. I also replace the head gasket from o.8 to 1.5mm.
4. fuel injector from 390 to 450cc
5. throttle body up grade to evo 111
6. fit an afc
my problem is when i put the afc little bit lean my exhaust manifold will red hot but if i put little bit rich it will be sluggish

need some help
i have been using this engine standard with no problem for 13yrs

 

[crazykatak]

spark plug heat range ?

 

[munky]

i thought exhaust manifold becoming red hot is normal when u rev the engine a bit longer

 

[wira hitam]

crazykatak, i`m using ngk iridium but not sure the range. i wll chk that. by way i`m using turbo s custom turbo manifold [banana]

 

[Dayline668]

AFR..? best set 11-11.5 AFR.

 

[wira hitam]

dayline668..do i have to carry out wideband tuning or get an afr meter

 

[Dayline668]

If u know what u doing, just get AFR meter to monitor n set yourself, overheating EGT will melt your piston n ring.

 

[wira hitam]

Dayline668.. u r rite, i try swaping the air flow sensor the problem solve.
lucky for me to get the advice from u guy.
thanks all guy`s

 

[peterfrancis]

Ignition timing is also a factor, might be retarding too much

 

[wira hitam]

yes the ignition also the factor but in my scene my stardard airflow sensor already max out unable to support the new injetor.it still run good on other stardard gsr rs and below

 

[jsop444]

Nice modification in the exhaust its good that you replace but can you tell me that what is the problem in the exhaust then you change the replace the parts?


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[wira hitam]

jsop444, actually there`s nothing problem with my exhaust sytem. only the air flow sensor unable to gift input to the injector