Are there any mods/things you can do to your car that can add horsepower or make your car faster WITHOUT having to get a retune? For example you have turbo'd a stock motor from TB to oil pan. I know you could do weight reduction but could you add a bigger TB or intake manifold WITHOUT getting a retune? This is just a general question about our turbo Honda's and not specifically for me. Maybe have your intake pull cooler air from outside the engine bay? Maybe something ignition wise?

 

if you alter a mathematical equation, the outcome changes.

 

OK so no, oh well

 

modifications to the chassis wont change anything.

any change to the drivetrain normally requires tweaking the tune.

 

You can do very basic stuff like a cai, lightweoght flywheel, and exhaust system without hurting the tune much.

I did that and also raised my compression from 9.2 to 10.7 and on my obd0 pr4 ecu it ran fine (afrs were good), but when I threw a b18b1 ls map on s300 the open loop map was super lean (17:1 wot yikes)

Took a while to get it tuned till the open loop map was good. I had to add something like 10% more fuel across most of the fuel maps. Idk if this is an s300 related thing or not though. Now im around 13.5:1 wot up to 4500rpm, then it richens up to about 12.5:1 to the redline.


But besides very basic stuff, you need a tune

 

Shorter gears = faster acceleration. If you're running the GSR transmission mentioned in your signature, get an SI, or even better an ITR/CTR transmission. Zero retune required.

 

The only problem with gearing that short is that 5th gear at highway cruising speeds results in crazy high rpm and horrible fuel mileage. IIRC my b16 in my em1 was at like 4,000rpm at 70mph

best option is to get a shorter trans and toss an ls 5th gear in it so you don't hate life on the highway... after all there's very little performance driving in 5th gear on the street.

 

Either people want performance, or they want driveability. You have to make sacrifices for one to gain the other when you're modifying a Honda.

Assuming 205/50R15 tires, a CTR/ITR transmission should be spinning 3804 RPM @ 70 MPH, whereas an LS/RS/GS transmission should be spinning 3227 RPM @ 70 MPH. It's not that big of a difference. Putting the LS/RS/GS 5th in the CTR/ITR transmission would put it at 3328 RPM @ 70 MPH. Quite frankly, that's a hell of a lot of work on a rather expensive transmission for not that much of a gain.

 

500rpm on the highway is almost a 10mpg difference.

 

Uh, bullshit, especially since we're talking about turbo cars. First off, prove it, and once you're done doing that, you might want to inform the EPA, because they disagree with you as well.

 

Isk about that 10mpg thing. I averaged 31.5mpg in my ls with an average cruising speed of 80mph.
I really doubt it would do 40mpg by dropping to 65-70mph

 

Especially with a turbo car... cruising at high rpm lowers the boost threshold for partial throttle. with a larger turbo 500rpm is the difference between part throttle acceleration under vacuum and part throttle acceleration under boost... so it makes a huge difference in fuel consumption

 

Light boost is beneficial for gas mileage, because it increases the VE of the engine without needing to greatly increase the fuel flow rates. I'm not saying rolling around at 15 PSI on the highway is going to do wonders for your gas mileage, but if you're sitting in the 1-5 PSI range on the highway, your gas mileage is going to be noticeably higher.

There are a LOT of factors that play into gas mileage, and even more so with a turbo car. Your blanket statement of 500 RPM = -10 MPG is misinformed at best, and straight misinformation at worst.

 

Most setups make way more than 5psi at partial throttle... small amounts of boost do help mpg but most high boost setups will make over 10psi at light throttle in 5th gear, murdering fuel economy.

 

In the past (Car was NA) I had shortened 3rd-5th gear set, 5th is 1:1

I lost about 2mpg on highway driving. City driving I gained about 2mpg.

Since my car is boosted now, the shorted gears would have been too much, And the car now has a 4.0 final drive drive.

I don't really have good data, since the final drive was swapped right after the turbo.