Increase rev limiter to 7300; 2003 Impreza rs

[Tireman28]

I really need more gear on the gear on the front stretch. If I can get 7300 rpm I’d be perfect. Any thoughts????

[L5wolvesf]

I've had problems with the site so I haven't followed what all came of the ECU change/mods. I'm guessing it isn't affordable or doable.

 

Given that . . . what about the gearing?

 

Is there a gearing change (either in the diff or trans that will put you where you need to be and . . . without messing you up elsewhere on the track?

[Tireman28]

That I’m not sure of. I’ve tried different stagger tires, bigger, and I’m still running out. I have a 4.11 trans now. 2 wheel drive front wheel. I have the rear end deleted. I can run the rear end, just not all wheel. That being said, i need to stay in 3rd gear cause it pulls great out of the corners and I’m not sure if putting the rear end back in will gear it down enough to pull the entire straightaway. If I had 7300 rpm I’d prolly b fine. But idk. I need some help figuring it out bad. Lol

[L5wolvesf]

There are gearing/speed/etc calculators online to help figure out some of it. 

First you'll need to know what diff gears (front or rear) are available for your car - then run the numbers. A slight tire size adjustment might work in combo with gearing. Same would go for the trans gearing. It might be you run a lower gear and have to up shift.

 

There might be a bit of a trade off between getting the RPMs you want vs which gear you accelerate out with. You might make one better but the other off a bit. 

 

Personally, I wouldn't sacrifice any handling (big stagger or tire changes).

 

What are your times vs. the fast qualifiers?

[Tireman28]

Everyone is running anywhere from 19.1-19.8. I’m around 20.2-20.6. Only cause I’m taching out 80 ft early on each straightaway. I’m working w the bigger stagger stuff now trying to find wat works. I’m also contemplating on putting the rear diff in and running rear wheel only and see if that will gear it down a bit. I have a 4.11 trans now, and I also have a 4.44 on the shelf.

[matt167]

4.44 isn't going to do you any good if your running out of usable rpm. A 3.90 transmission would be the cats meow.. If you want to bump the rev limiter. MSD DIS-2 ignition boxes ( discontinued but obtainable ) will work for you. The Midget race box will as well and it's in production.

[Tireman28]

What’s a midget race box? Never heard of it. And the msd Orion is that just a ignition coil? Or a kit? And where can I get one

[matt167]

It's a programmable race version of the DIS 2 box. It's the only DIS-2 that is in current production..

 

Looks like the tech manual for the DIS-4 says it can be used on 4cyl also. ad listings suggest 6-8 cyl only.

 

https://www.msdperformance.com/products/ignitions/distributorless/parts/62152?gclid=Cj0KCQjwz7rXBRD9ARIsABfBl82f5nnRfJ8zFkLTzyYI6tMRfYcCpKodpLDdA7x_mpgdZJF8SP-99ssaAsWfEALw_wcB

[Tireman28]

Wat do u suggest?

[matt167]

I would use the DIS 2 or 4 box . They will give you better spark timing ( adjustable ) and you can tweak the rev limit.. You might want to call MSD to get the right part number that will work and to increase the rev limit. They make a few variations

[Tireman28]

Dis 4 looks more modern and more tunable I guess. I’ll calll though and make sure. Thanks a lot guys for ur help

[Tireman28]

Msd said none of there products will work with my car

[matt167]

I know the DIS-2 does, since it was used in the past on Subaru. They probably don't have the testing in place.

 

In any case you do have other options.. Megasquirt 2/ Microsquirt injection is probably where I would go. They are used on Subaru all the time. $300, you can just mount it on the firewall and use part of the original harness. There is also DIY PNP setups where they fit in an OEM ecu case.. You would need a WRX or other 36 tooth crank sprocket as MS2 works best with it. It's a race car so idle air control functionality is moot.