Hi,

Been reading a fair bit of engine tuning recently. Was wondering what what point upratnig the injectors is a worthwhile spenditure?

In respect to the standard injects on the 98 STI. What power levels should i think of upping the injectors/do the original ones start being restrictive?

Would be interesting to know/eventually budget for.

Cheers
Chris

 

I'd be interested in this also

 

We've looked into this for our track impreza, and general concensus seems to be that the Yellow Top injectors (standard on an MY98 STi) are good for approx 340bhp.

If you're looking for more than this then upgrading is a must, however only upgrade to the smallest injector size that will supply your power level, if that makes sense... as injectors that are too big tend to cause some rough idle issues.

Obviously other supporting mods must be completed before looking to change the injectors. An upgraded fuel pump is the starting point (Walbro for example) as this is the biggest contiributor to good fuel pressure supply, then an adjustable FPR is a good idea for tuning purposes although not essential.

Your fuel pump should be the first thing to look at really, before changing injectors.