RB20DET Vs. SR20DET?

Post by **Sandmann** » Tue Mar 18, 2003 1:32 pm

I read the RB25DET vs. SR20DET. But I wanted to know how these two match up? Which one is recommend for daily driven and reliability. Why would some onr do the RB20DET Swap over the SR20DET? I am pretty sure the RB preforms much better stock than the SR as for numbers. But what you you guys recommend and why. Other comments are much welcomed.

Thank you in advance.

Post by **Nathan** » Tue Mar 18, 2003 1:32 pm

Actually, the SR has slightly higher torque, the RB has slightly higher horsepower than the SR (depending on the model of SR, but assuming a red top or black top from an S13) What you gain with the RB swap is that it is a more unique engine, and well...its an inline 6 so from what I understand it's probably smoother as well. The RB engine is cast iron whereas the SR is aluminum so I think (not going to take the time to find the engine weights thread) the RB weighs a bit more, but not enough that I would worry about it. Both are very strong engines and unless you plan on putting more than 350 hp to the ground then I dont think it would matter a whole lot. A few problems you might run into are the need for a different crossmember for the RB20, when you can just use the stock one with the SR. Also, there has been some talk fo whether or not with stock engine mounts the gear shift will end up in the center of the whole and whether or not you will be able to put a front sway bar on because of issues with clearance with the oil pan. Finally, I dont think you can use the stock fan, I think you have to switch to electrics because of the small amount of room between the front of the engine and the radiator (someone correct me if I am wrong. Personally, I dont know for sure which I will go with but I am leaning in the direction of the SR because I know it will fit, the wiring shouldnt be as hard (more information on it) parts are a bit easier to come by, and I will be on a limited budget. Anyway, I hope I was of some help and if I screwed up anything, someone correct me!

Post by **Sandmann** » Tue Mar 18, 2003 1:32 pm

Thanks Nathan. Much appreciated.

Post by **Nathan** » Tue Mar 18, 2003 1:32 pm

No problem, one thing I forgot that I understand to be a key difference is in the valve train of the two engines. The SR's valvetrain isnt very good once you start really revving it >7500 rpm while the stock RB20DET valvetrain can handle 8000 stock according to Megalla in another thread I found and can be raised to 9000 with some other modifications. Of course, so can the SR, but the extra 500 rpm stock is nice. Finally, my favorite part of the RB20DET is the iron block...somehow I just dont like the thought of aluminum, but we will see, I might very well end up with it! Oh, and I finally got around to looking up the engine weights and the RB20DET only weights 25 lbs. more than the SR (the SR is 535 lbs. the RB is 560 lbs.) this is hardly enough to care about. Apparently the reason the difference is so small despite the fact that the SR has an aluminum block is the fact that they used a lot of aluminum in order to keep it just as strong. I heard that one reason they did this is because they wanted to use an aluminum block with an aluminum head to prevent warping of the head as the metals expand at different rates (the RB has an aluminum head with a cast iron block)

Post by **Sandmann** » Tue Mar 18, 2003 1:32 pm

Thanks Night, yeah I ment RB20DET. So I am guessing there isn't much different between the RB20DET and the SR. What about potential MODS would the RB20DET put more to the ground?

Post by **ZERO** » Tue Mar 18, 2003 1:32 pm

It has been said on these boards that the RB20 and the SR both run out of steam at 400hp. I could see that being for the SR, but it has to be more than that with the RB20. Night, could you please confirm this?

The price for mods is a little higher I think with the RB, because you are dealing with a 6cyl. engine instead of 4. As for aftermarket support there is just as much aftermarket for the RB as there is for the SR. It's just a question of availability.

Post by **ZERO** » Tue Mar 18, 2003 1:32 pm

Then what advantages are there to having the RB? are there any long run advantages? can the RB hold more boost? There has to be a tradeoff.

The RB is a little cheaper.The RB is heavier, not by much though.The aftermarket has more availability in the US for the SR.The SR has more torque to start out with, but the RB has more hp.Parts are more expensive for the RB.The SR can be displaced to 2.2 lt and the RB can be displaced to 2.3, 2.4 lt (correct me if I'm wrong).

Do you see what I'm saying? I dont mean to bash or anything, but I want to know if there is anything other than price in which the RB20 is better than the SR20. There has to be a trade off. The RB will be cheaper to beggin with, but it will become expensive in the long run.

Post by **Sandmann** » Tue Mar 18, 2003 1:32 pm

The labor of the RB20DET would be more unless you are doing the swap yourself. Trade off: Bragging Rights?

Post by **Imissmyturbo** » Tue Mar 18, 2003 1:32 pm

Lets not forget the RB block is stronger then the SR. That isn't a factor till you get over 400 WHP but if that is in your distant future it's somthing to consider.

Post by **ZERO** » Tue Mar 18, 2003 1:32 pm

quick question.Can a 240 with a stock RB20 take out a moderately modified WRX (by modified I mean: Intake, Cat-back, Boost Controller<the stock WRX ECU will not let the boost go over 17>) ??

I have a grudge with a certain friend who screwed me over?

BTW: stock boost on the WRX is 13psi, this guy is rinning 16psi...

Post by **ZERO** » Tue Mar 18, 2003 1:32 pm

Any body have any thoughts on this???...

Post by **themadscientist** » Tue Mar 18, 2003 1:32 pm

WRX, hahaha. I reeled a brand new one in quite readily with a $1500.00 automatic GTS-T Skyline, no worries.

Post by **ZERO** » Tue Mar 18, 2003 1:32 pm

Thanx mad, thats all I needed to hear...Hey wait a second...dont you live in Japan?Was it an STI?

Post by **themadscientist** » Tue Mar 18, 2003 1:32 pm

Post by **cosmo** » Tue Mar 18, 2003 1:32 pm

correct me if I'm wrong but the RB20 puts close to 220rwhp and the red top SR puts about 170-175rwhp.

The RB would be cheaper to get about any power level short of a rebuild (i.e. 400 hp). And it would spool a bigger turbo faster due to the 2 more cylinders.

The SR is lighter(barely) and has more parts available in the US.

If it were me I'd go RB, then I could say I've got SKYLINE POWA! and watch the ricers bow to me.

Post by **Redline240** » Tue Mar 18, 2003 1:32 pm

cosmo wrote:correct me if I'm wrong but the RB20 puts close to 220rwhp and the red top SR puts about 170-175rwhp.

The RB would be cheaper to get about any power level short of a rebuild (i.e. 400 hp). And it would spool a bigger turbo faster due to the 2 more cylinders.

The SR is lighter(barely) and has more parts available in the US.

If it were me I'd go RB, then I could say I've got SKYLINE POWA! and watch the ricers bow to me.

I say get the RB26, then everyone will bow....even the car gods themselves, lol....

Post by **themadscientist** » Tue Mar 18, 2003 1:32 pm

havin driven and fought with both, the RB20 and SR20 in the same car will get you about the same level of performance so it come s down to personal preference. RB25 is better than both in the long run and RB26 better than that.

Post by **dcdrifter** » Tue Mar 18, 2003 1:32 pm

You need a couple of mods to hang with your buddy in the wrx.

Oh, and rb25's do rule.:ylsuper

Post by **ZERO** » Tue Mar 18, 2003 1:32 pm

we will see eventualy

RB20DET Vs. SR20DET?

RB20DET Vs. SR20DET?

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