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View Full Version : from rb20 to sr20 or rb25. Help please.


lg54
03-03-2011, 10:27 AM
First of all helloo, hope u all are good.

Yes i've searched but couldn't find a definitive answer.

Currently i have a rb20. looking to upgrade to either an sr20 or rb25.

i know that in order to achieve 400whp, you don't need to forge the rb25, but do you have to forge the sr20? what is the sr20 internal limits?

transmission wise, if i end up going rb25, i could use my rb20 tranny. sr20 trannies how much whp can they hold?

in order to go sr20, what changes must i do in order to do the swap? engine harness, motor mounts? driveshaft?

today, which one is a better bang for buck in order to achieve 400whp? which one is less expensive to mod to get to the 400whp zone?

thanks for the help! :hide:

Chaluska
03-03-2011, 12:14 PM
1 - i know that in order to achieve 400whp, you don't need to forge the rb25, but do you have to forge the sr20? what is the sr20 internal limits?

2 - transmission wise, if i end up going rb25, i could use my rb20 tranny. sr20 trannies how much whp can they hold?

3 - in order to go sr20, what changes must i do in order to do the swap? engine harness, motor mounts? driveshaft?

4 - today, which one is a better bang for buck in order to achieve 400whp?

5 - which one is less expensive to mod to get to the 400whp zone?



1- if the engine is going to be out of the car to begin with, why not toss in a rod/piston combo for piece of mind.. a REALLY good tune will net 400 on either engine, how long it lasts is a different story.

2-RB20, SR20, KA24, CA18... all the same tranny

3- Engine mounts, tranny mount, drive shaft, harness

4- LSX

5- this is a joke right?

SlowMotion
03-03-2011, 12:37 PM
Currently i have a rb20. looking to upgrade to either an sr20 or rb25. :hide: I wouldnt call a sr20 an upgrade from a rb20... More of a side step. In order to reach your goal, the rb25 is hands down the way to go. You are looking at a $2000 upgrade that can handle what you want vs a fresh start on on a sr swap that will run you $5000 (unless you do it yourself) plus need a few grand worth of mods in order to keep it reliable. I would look into ka-t! Bang for the buck, cant beat it! Plus u can still buy parts for it at your local auto parts store.

lg54
03-03-2011, 01:09 PM
Thanks for the reply guys.

I've been researching and upgrades for the sr20 seem less expensive than for the rb25.

In order to get to the 400whp zone I'm planing upgrading turbo, injectors, etc.. I'm really not looking to forge anything right no, so I'm looking to see which one is more reliable and will be a wiser pick.

Also, rb25 is a heavier engine so it will mess up my weight distribution on my 240sx hatch.

I guess the rb25 is a wiser pick since I already have half of the job done.