i need some help on tunning a 13bre cosmo block which i semi pp ported
, im running a t72 the block has 9.4 rotors, i heard people running timing retard as much as 24 deg on leadings ,im using a locked distributor at 12 btdc on leading and 2 for trailing , the car pop so then i rearded the timing 15 btdc on leading and 5 trailing and cleared a bit more but still pop a lil bit, im runing 20 psi on manual boost controller this is on my 74 rx3
thanks julio

 

Put a wide band on it first an see what a/f ratios you're running . Excessive popping usually means that you're running rich. As for the timing , I dont mess with mechanical distributors , but I think 13-15 deg. @ 15psi and up is advance on the leading is "standard" on a turbo rotary.

 

I haven't heard of a "semi" pp motor..... is that like being a little bit pregnant?

 

semi pp means keeping all your original ports and adding a smaller pp 1" to your rotor housings

 

speedturn, you used a Blake-ism.

 

When I was tunning my car for emissions, it used to pop a lot at 14.4-14.8 AFR (under vac).

BTW - I am not saying you are wrong, just sharing my experience.

 

what kind of gas?

 

Either 87 or 89 (can't rember which) on a overdose of premix.

 

big turbo + high compression + lots of overlap + pump gas = BOOM

i'd start really low...like maybe 10 and get it on the dyno and pay really close attention to egt's. how much boost?