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View Full Version : RB25DET Swap 240SX


jdm_s14
07-25-2003, 09:27 PM
just wondering what everyones opinion is on this swap. i have been thinking about the pros and cons to this. the only real con i have found was the weight. in the new scc, they say the ka24de weighs about 540 pounds, and the rb25det weighs 720 pounds. is 180 pounds going to make a huge difference in the weight distribustion of the car? what is the weight distribution with the ka24? the big advantages i have been noticing over an sr20det is first, the rod/stroke ratio. the sr20det has a 1.58:1 r/s ratio, and the rb25det has a 1.69:1 r/s ratio. according to a few sources (teachers at tech school for auto mechanics), a 1.75:1 r/s ratio is ideal. another benefit of the rb25det is the already higher displacement, while still keeping a relatively short stroke. i think i will end it here as i am ranting on now. thanks for your opinions.

http://us.st12.yimg.com/us.st.yimg.com/I/yhst-3060391942628_2021_3405762
RB25DET SWAP DVD
http://store.driftingshop.com/rb24sdv.html

p.s. another con is parts availibility if something breaks...any ideas?

J-BloodAE86
07-25-2003, 09:45 PM
yah, i have seen this before in an S14, hella tight, wieght distrubution would probably be screwed due to the wieght and also because of the longer over all length of the block. Id take some planning and/or alot of trial and error to set it up right, but if you do it, id be very unique and hella tight to say the least

7akumi X
07-25-2003, 09:54 PM
If your gonna go for the swap go for the more available rb26dett this is very powerful motor compared to the rb26det the second turbo brings to the table what it should. With a new CPU in it, sometimes said that it can produce 320 properly tuned. The original CPU on it is restricted to 280 because of Japanese government agreement with automotive companys, I although belive it is probably more capable then that.

marshun
07-26-2003, 01:42 AM
yeah the rb26det is pretty cheap compared to an sr20det. also i've read somewhere (prolly 240sx.org) about the weight difference of these motors. its something like 80 lbs i think. idunno though. i think you should just stick with the motor thats in there already. just so if you blow the water pump or something then you wont have to order one from over sea's. yknow what i mean? :)

16ggsx
07-26-2003, 07:37 PM
If your gonna go for the swap go for the more available rb26dett this is very powerful motor compared to the rb26det the second turbo brings to the table what it should. With a new CPU in it, sometimes said that it can produce 320 properly tuned. The original CPU on it is restricted to 280 because of Japanese government agreement with automotive companys, I although belive it is probably more capable then that.
Whoa! Where the hell are you guys getting your info from?!? There is no way the rb26dett is "more available" than the rb25det. Plus, they're about $1000 to $1500 more than the rb25.yeah the rb26det is pretty cheap compared to an sr20det. also i've read somewhere (prolly 240sx.org) about the weight difference of these motors. its something like 80 lbs i think. idunno though. i think you should just stick with the motor thats in there already. just so if you blow the water pump or something then you wont have to order one from over sea's. yknow what i mean? Now I'd like to see where the rb26dett is cheaper than the sr20det. Maybe the rb20det, but no way in hell is the rb26dett cheaper than the sr20. The rb25det in the s14 is a hella sick swap, but you'll pretty much have a straight line monster. I've seen a couple in miami, and they can't turn for squat. Also, the s14 suspension will have problems coping with the power of the 2.5 after you put a couple bolt-on mods. It all depends on what you want to get out of the car. If you want to drift, your gonna want better weight distribution, and the sr20det or your ka24de-t would be a better handling car with gobs of power.

jdm_s14
07-27-2003, 07:34 PM
i did a little more reading, and from what i gathered, a lot of the weight added to the car is in the beefier tranny. i also read that it adds the weight in the right place (more towards the middle of the car, and fairly low). im not sure at this point. i think i will try to do some math, and see just how much it messes up the weight distribution.

JonnySlick
07-27-2003, 07:56 PM
Originally posted by 16ggsx
Whoa! Where the hell are you guys getting your info from?!? There is no way the rb26dett is "more available" than the rb25det. Plus, they're about $1000 to $1500 more than the rb25. Now I'd like to see where the rb26dett is cheaper than the sr20det. Maybe the rb20det, but no way in hell is the rb26dett cheaper than the sr20. The rb25det in the s14 is a hella sick swap, but you'll pretty much have a straight line monster. I've seen a couple in miami, and they can't turn for squat. Also, the s14 suspension will have problems coping with the power of the 2.5 after you put a couple bolt-on mods. It all depends on what you want to get out of the car. If you want to drift, your gonna want better weight distribution, and the sr20det or your ka24de-t would be a better handling car with gobs of power.

yeah i was thinking the same thing as you bro...just didn't say it! LOL. cheaper, more available? where'd you guys see that? i've found all the RB motors to be harder to find (and harder to find parts for) and way more expensive.

anyway, if you're gonna' make a wangan car, then i say go for the gusto and drop in the RB25 or RB26, then mod it! i love wangan and one day i'd love to build a s14.5 with a RB26dett in it and ikeya (spelling?) sequential shifter! hella' tightness.

for drift, stick w/ the KA and turbo ready it, or go SR20 or CA18 (which i'm a huge CA18 fan...but that's another story).

MrMigs
07-29-2003, 11:17 AM
an RB25 will change the balance a little bit, but not so much that you wouldn't be able to tune it out through suspension settings.