Hi all. At a rolling road day back in November I was very pleased to see my rebuilt STi V4 produce 302 bhp and 256 lb ft torque with just a decat (everything else standard including ECU and run on V Power without booster). The bhp is slightly higher than the claimed factory figure and the torque figure is pretty much spot on.

Now, I noticed on the day that later cars have much better torque figures. There were UK Turbos and Jap WRX's that were producing less bhp than my car but more torque. Two things.

1. Why do the later cars have this greater torque?
2. What's the best way to increase my torque figure?

Answers in terms of tuning 'stages' would be very helpful. I believe 'stage 1' would be to port the headers?
Thanks

 

Stage 1 would simply be to remap what youve got.

 

Unfortunately not without a new ECU!
Edited to say: I have seen a V4 STi with a Power FC and decat only, and that produced 270 lb ft which is hardly what I expected. I thought the remap would have given more. However, that car is only one example.

 

well true, but if thats the case, what are you expecting to achieve with ported headers?

They would need to be allowed for in the map, they wont gain you any torque at all. The key thing is adjusting the map, bolting stuff on wont increase much at all, with the side effect of reducing engine safety.

 

Hi, yes I know the ECU and map are very important but I think what I am trying to understand is the mechanical extras that are required to increase torque. For example, I know an STi V6 that only has a sport cat and remap and that car produces 310 lb ft (or thereabouts). Comparing to the v4 I mention above, what is it that is giving so much more torque?

 

Possible down to the specific map as you can map for torque or BHP, also could be down to condition on the day of the dyno session ambient temp etc.

Or could be one of many many other reasons

Damo

 

I think there is something else in it. Through my research it seems later cars can make more torque no matter whether they have a standard map or have been remapped, compared to standard or ECU'd and mapped earlier cars. Is it pistons? the turbo? crank? (Although mine has the version 9 crank and I didn't see any leap in torque)

 

Any of the tuners out there with an opinion/facts?

 

Had a look in the FAQ on SIDC and the Torque figure did change through the years, the most significant change came when the "phase 2" engine was introduced with different inlet manifold and injectors.

Must be that but I'm still not really sure

Please correct me if wrong

Damo