Hello everyone. I just have a quick question. If I tuned my hatch on a GSR turbo swap with a B16 trans which made 280 HP for being bone stock nothing to special. If I swapped that B16 trans for a GSR trans recently, do I need a retune? From what I'm hearing because we switched the trans to a GSR the car should be somewhere right now around

350-306 HP. When I punch it it feels quicker that's why I'm wondering if I should even bother tuning? I do feel the power difference.

 

yes and no. depends if its a street car that you drive hard, you should be ok. if its a track car you might want to retune. since the GSR gearing ratios is a bit different.

 

thanks for this info ! I mostly run it on the street and do freeway pulls ! I’m only 20 so I only tracked it 2 times on the b16 trans. As of now I do feel that power difference. I think since GSR has longer gears the boost builds up a little more, which makes me feel more power, and people tell me I should be running more hp now. Thank you 👍

 

Changing the trans does not increase or decrease your power. What you are feeling is the change in tractive effort with your new gear ratios. Normally the car would feel quicker going from the longer gears to the shorter gears (GSR --> B16), but it's possible that the bigger drops are helping you to optimize the torque curve of your engine better, i.e. you are closer to peak torque after a gearshift.

Torque is what will get the car going from a start, power is what will pull you at speed.

If you are lucky enough to choose your gear ratios, the general best practice is to shift just past peak power and drop into the next gear right at or just before peak torque. If you can't choose your ratios, it's all about looking at your dyno sheet and planning your shift points. Lower gears you want to aim to drop into the next gear near peak torque, upper gears you want to stretch out to just past peak power. If you've got a fat, flat-ish torque band, say you carry +/-10 ft-lbs over 1krm or something, you've got a lot more flexibility and can focus on stretching it out to max power in each gear.

You shouldn't need to retune for a different gear stack, but there are likely some features in your calibration that rely on the gear ratios so you need to update them in the cal. If you are running boost by gear or something, this may need a touchup too. Shouldn't be anything mega though, and could likely be done just fine on the street or preferably at the track.