Did a search...Twins on RB20/25...

[easymmkay240sx]

I remember not too long ago there was a post about a company making an adapter to use the twins off a GT-R on an RB20 or RB25.

I did about 10 searches and I may not have used the right words, but I used all the ones I could think would fit it....so if anyone has any info, let me know please :>

[NISMO_RB25]

I could be wrong but I think it was undergroundmotorsportsmight we worth shooting them an email to see.

[JonPowell]

Chris at Underground Motorsports is indeed the one selling those adapter flanges.

http://www.underground-motorsports.com

[JustinStrife]

I know it's just an opinion...

But wouldn't it make more sense just to go ahead and do the RB26DETT if you HAD to have twins?

The cost would probably be pretty close, and I imagine the 26 would be the most efficient power wise for two turbos....

Just an opinion

[Nameless EJ6]

Two turbo's on two liters... that's like a Twin turbo Honda 4 banger... totally pointless when you can make good power with a good single turbo.

The RB25 would probably be ok to twin turbo because of it's displacement.. but putting the GTR twins on the RB20 is a terrible idea IMO.

[dekand]

I agree, it would be much cheaper and EASIER to upgrade to a nice single turbo ... it just doesn't make much sense to go through all the trouble just to have twins...

[JustinStrife]

plus you're taking up that much more space in your engine bay, AND creating more heat and more chances of mechanical failures... Just no real point.

[SeVa-S13]

If that thinking is true, then all the GT-R and Supra owners that upgraded to bigger twins are retarded, right? What makes this idea viable is the fact that besides the downpipe, it's relatively easy to do because the manifolds are already made and fit (with a spacer mind you) instead of wasting a ton of many on a custom twin manifold which is the only gripe with basis against inline engines going TT. The parts are all available, and relatively cheap if you have either a hook-up or watch on ebay long enough.Don't be so closed-minded. With this setup, an RB20 could easily reach 400hp and have a great powerband, unlike those who go with the huge T3/T4's with awful trims and don't start spooling 'til 4k.

[Nameless EJ6]

If that thinking is true, then all the GT-R and Supra owners that upgraded to bigger twins are retarded, right? What makes this idea viable is the fact that besides the downpipe, it's relatively easy to do because the manifolds are already made and fit (with a spacer mind you) instead of wasting a ton of many on a custom twin manifold which is the only gripe with basis against inline engines going TT. The parts are all available, and relatively cheap if you have either a hook-up or watch on ebay long enough.Don't be so closed-minded. With this setup, an RB20 could easily reach 400hp and have a great powerband, unlike those who go with the huge T3/T4's with awful trims and don't start spooling 'til 4k.

Closed minded? Right. You don't need two turbo's to have a "great powerband"on a small engine.. and upgrading a single turbo doesn't automatically mean you're going to have a huge spool up and no respectable powerband. That is not what I meant, and if that's what you're thinking, then I think you should reevaluate your definition of closed minded and see how well that fits yourself.

My point is that there is no need to go through the trouble of upgrading a two liter engine with two turbo's. If one is thinking about doing that, one should ask themselves what will two turbo's give you that one won't? A "great powerband" is a rediculous argument. Those two turbos are built for an engine with alot more displacement making alot more power. Ya sure you'd be boosting more on the RB20 with them.. and I'll be willing to bet because of it's displacement those two turbo's will make for an AWFULL powerband. There is no law that states two turbo's will give you a better outcome than one. That's especially true for small engines. The RB20 is a small engine. Nissan put a single turbo on it for a reason. They looked at their power goal and realized that one turbo would suffice perfectly. With the RB26, they needed to make ALOT more power.. and in order to scoot the big AWD car along swimingly, one turbo wouldn't be practical.

I'd be really interested in seeing a dyno of a tuned and untuned RB20DET with the GTR turbo setup running 7-10 psi..

[SeVa-S13]

Let's not infer what isn't there. I never said you needed two turbos for a nice powerband or that two were even better than one. (I myself am going with a single for my 20)

I'm just damn tired of people bashing the idea just because the engine is a whole .6 liters smaller than the "massive" RB26. You ask what two turbos could give what one turbo could not, and then say that a single turbo was not "practical" enough for Nissan to use on the GT-R. Let's try to to keep the contradictions to a minimum.

Seeing that my main point was grossly missed, let me remove its meticulously devised veil ( ) and say it as simply as possible. --Two or one, they both work. They both have advantages and disadvantages.

(To be honest, I don't think there's any real merit in swapping from a single to a dual setup other than bling factor. Despite the modest response gains, the heat and fitment would probably discount any advantage. The only reason I think the GT-R setup isn't a bad idea is because all the parts are already somewhat accessible and the turbos are a decent upgrade over stock. I know you said that the Twins on a 20 would make for an "AWFULL" powerband, but when upgrading turbos on cars, don't most people get a larger turbo? Thought so. And that's what? a .3 liter difference per turbine? People are constantly taking turbos meant for larger engines and applying them to their cars because they want more power. Plus, the GT-R turbos are ball bearing and have ceramic compressors so spool and response should be pretty damn acceptable to an enthusiast looking for an upgrade. Not to mention the bishez that swoon when they see two snails. )

[Carl H]

i bet a pair of gt28rs turbos on the twin setup bolted up to a rb20 would do quite well.

[Nameless EJ6]

Let's not infer what isn't there. I never said you needed two turbos for a nice powerband or that two were even better than one. (I myself am going with a single for my 20)

I'm just damn tired of people bashing the idea just because the engine is a whole .6 liters smaller than the "massive" RB26. You ask what two turbos could give what one turbo could not, and then say that a single turbo was not "practical" enough for Nissan to use on the GT-R. Let's try to to keep the contradictions to a minimum.

Seeing that my main point was grossly missed, let me remove its meticulously devised veil ( ) and say it as simply as possible. --Two or one, they both work. They both have advantages and disadvantages.

(To be honest, I don't think there's any real merit in swapping from a single to a dual setup other than bling factor. Despite the modest response gains, the heat and fitment would probably discount any advantage. The only reason I think the GT-R setup isn't a bad idea is because all the parts are already somewhat accessible and the turbos are a decent upgrade over stock. I know you said that the Twins on a 20 would make for an "AWFULL" powerband, but when upgrading turbos on cars, don't most people get a larger turbo? Thought so. And that's what? a .3 liter difference per turbine? People are constantly taking turbos meant for larger engines and applying them to their cars because they want more power. Plus, the GT-R turbos are ball bearing and have ceramic compressors so spool and response should be pretty damn acceptable to an enthusiast looking for an upgrade. Not to mention the bishez that swoon when they see two snails. )

Contradiction LOL. I don't think I came through to you on my post, it's obvious. "Lets" not try to act condescending here either, neither of us are children.

.6 Liters is not alot. I don't say the RB26 is a massive engine either. But for THE POWER GOAL they needed to attain with the RB26, (270+hp) ONE turbo wasn't practical. How many engines in production over 250hp have one turbo?

I am aware of the reason for putting a bigger turbo on an engine to make power. But putting TWO bigger turbos on a 2 Liter engine is rediculous. Argue that all you like. If you want the same amount of power on an RB20 that an RB26 has, instead of using the 2 Liter engines small exhaust pulsations to power two T25's, it'd be ALOT easier to make even more power with 6 runners into a single. If you don't get my point I don't know what to say.

i bet a pair of gt28rs turbos on the twin setup bolted up to a rb20 would do quite well.

Probably.. and I'd bet a single GT28R would be even more efficient unless you're really inclined to get 600hp out of 2 Liters.
Modified by Nameless EJ6 at 12:03 AM 10/29/2004

[SeVa-S13]

I am aware of the reason for putting a bigger turbo on an engine to make power. But putting TWO bigger turbos on a 2 Liter engine is rediculous.

Dunno if that was just a mistake but the GT-R turbos are smaller than the stock 20's T28/T3 Hybrid thinger.

The STi and EVo both make plenty of power with their one turbo, but I honestly have no idea what that has to do with any of this. We are aftermarket tuners, who gives a crap about what manufacturers equpiied the engines with? We all know damn well that manufacturers traditionally error on the side of driveability versus actual performance. (I.E.-The Z31 Turbo. Unintercooled setup with a relatively small turbo for the engine size, then in '88 they made it smaller. C'mon, that's pretty lame.)

"Your point" of a single probably being better is pretty much an accepted fact for inline engines and I never argued it. But what you started out saying (along with plenty of other people because we know this isn't a new discussion) is that it's a terrible idea when in fact it's relatively easy and cheap to do and can wield good gains. I've already adressed all the facets of why it's viable in my previous post I think so I'ma go make a sammich.

[TheOne]

its a 6 cylinder, not a 4 cylinder civic........it'll be able to use a TT setup with 2 small turbos and it'll make good power.

displacement doesn't always replace technology.

[dekand]

The point is, you could get a nice single turbo and get just as good of a power band and hp gains for WAY cheaper than the TT setup, it is just not practical. Aren't the adatper plates from Underground like 400$ or something ... thats a bit rediculous, I couldn't find it on the site but i seem to remember them costing that much, because you still have to buy the turbos...

Point is, get a nice single turbo and save your money, the outcome will be the same or better if you choose the right turbo.

[BoostFab]

The point is, you could get a nice single turbo and get just as good of a power band and hp gains for WAY cheaper than the TT setup, it is just not practical. Aren't the adatper plates from Underground like 400$ or something ... thats a bit rediculous, I couldn't find it on the site but i seem to remember them costing that much, because you still have to buy the turbos...

Point is, get a nice single turbo and save your money, the outcome will be the same or better if you choose the right turbo.

i totally agree.

[Nameless EJ6]

Dunno if that was just a mistake but the GT-R turbos are smaller than the stock 20's T28/T3 Hybrid thinger.

ok, I made a mistake. However, on an inline 6 non sequential twin turbo, both turbo's make combined power. So add the specs of the GTR turbos together and compare them to the T3 hybrid they use on RB20/25DET's. It might be a good basic upgrade if you plan on running 15psi... but I certainly don't see a point on two Liters. The GTR twins would likely be too laggy and unefficient untill they're fully spooled..

There is so much to the argument between twin turbo non sequential vs single turbo. Camshaft design, displacement, turbo size, compression.. it's really too much effort to debate it. The concensus is, the GTR twins on a stock RB20DET is pointless. A ball bearing quick spooling large single turbo is much more feasible on two Liters than a stock GTR setup.

its a 6 cylinder, not a 4 cylinder civic........it'll be able to use a TT setup with 2 small turbos and it'll make good power.

displacement doesn't always replace technology.

Turbo's are far from technologically advanced. The concept of a compressor has been around just as long as combustion. The only real tech about a turbo is its size.

And if you understand firing order, you'll see that a 6 cylinder is the same concept as a 4 but with two more cylinders. So ya, a TT 2 Liter 4 cylinder is just about the same as a 2 Liter 6 cyl TT.

[rbsileighty]

And if you understand firing order, you'll see that a 6 cylinder is the same concept as a 4 but with two more cylinders. So ya, a TT 2 Liter 4 cylinder is just about the same as a 2 Liter 6 cyl TT.

Between physics and 500cc/cyl vs. 333.33cc/cyl there are a lot of differences in a 2L 4 vs a 2L 6cyl.

A set of small, well spec'ed T25's would do wonders on a 20... if you were going to run recycled turbo's (ie GTR turbos) I agree that you shouldn't waste you time and should just use that money you saved for a RB25, Z31, or 57Trim T3/T4 turbo with some new brake pads and rotors or brake kit to slow the now faster car down.

[Nameless EJ6]

Between physics and 500cc/cyl vs. 333.33cc/cyl there are a lot of differences in a 2L 4 vs a 2L 6cyl.

A set of small, well spec'ed T25's would do wonders on a 20... if you were going to run recycled turbo's (ie GTR turbos) I agree that you shouldn't waste you time and should just use that money you saved for a RB25, Z31, or 57Trim T3/T4 turbo with some new brake pads and rotors or brake kit to slow the now faster car down.

I'll continue to disagree untill someone proves me wrong. Which it would be quite hard to prove me wrong because of all the variables and technicalities. Two turbo's on a 2L engine is going to lag down low, big time. I wouldn't be suprised if they make good power up top above 5k.. but the powerband will be nothing like a GTR without it's displacement. You don't even need physics to explain that. More torque and combustion gasses = more efficiency in the turbo/s. Without the same amount of combustion and exhaust flow in the 2.6, the turbo's, which were made and specified for a 2.6L engine, will lag down low. Turn up the boost you might see a small gain, but doubtfully anything special in the low end.

[rbsileighty]

I'll continue to disagree untill someone proves me wrong. Which it would be quite hard to prove me wrong because of all the variables and technicalities. Two turbo's on a 2L engine is going to lag down low, big time. I wouldn't be suprised if they make good power up top above 5k.. but the powerband will be nothing like a GTR without it's displacement. You don't even need physics to explain that. More torque and combustion gasses = more efficiency in the turbo/s. Without the same amount of combustion and exhaust flow in the 2.6, the turbo's, which were made and specified for a 2.6L engine, will lag down low. Turn up the boost you might see a small gain, but doubtfully anything special in the low end.

A set of small, well spec'ed T25's would do wonders on a 20... if you were going to run recycled turbo's (ie GTR turbos) I agree that you shouldn't waste you time and should just use that money you saved for a RB25, Z31, or 57Trim T3/T4 turbo with some new brake pads and rotors or brake kit to slow the now faster car down.

[BoostFab]

the only way to really find out the result is, "just do it".....

[Nameless EJ6]

Yes, I can read.

I agree with "waste of time"... but that's plays into my disagreement with anyone who wished to throw two turbo's on a 2L engine.

[rbsileighty]

Yes, I can read.

I agree with "waste of time"... but that's plays into my disagreement with anyone who wished to throw two turbo's on a 2L engine.

I'm not attacking you bud... so no sore feelings ok. I've missed things in posts and replied wrong before, so I thought you might not have noticed what I had said.

Two small, correctly sized turbo's should produce a very nice powerband...

the only way to really find out the result is, "just do it".....

Once I buy my house at the end of 05 or beginning of 06 and things start settling down again... this was what I planned on replacing my T3/T4 with...