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S15 Turbo Discussion

TTT

By TTT,
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TTT Grand Master

TTT

Posted
Posted

yes - doesn't fit directly on to an RB20

yes - would cost more to fit than it's worth.

but my question is this.

why is it that an SR20 in an S15 can pull 220rwkw with stock turbo by changing almost everything else like cams, cam gears, ecu, and all supporting mods to run this turbo at about 17-18 psi boost, but same can't be done using this turbo on an RB20?

do any of you peeps know the specs of an S15 turbo?

If I recal it is supposed to be a 320hp turbo (or was it 280)...

anyway, let say for example, you bought this turbo and it came already bolted to an aftermarket RB manifold with all required lines for oil and water and dump pipe to fit directly on to your rb20.

what would be required to make the same 220rwkw out of it?

would it make it?

would it require more boost in the RB than it does in the SR?

I'd guess that the rb's lower compression would need attention.

DISCLAMER: this is purely hyperthetical.

no need to come on here to say things like why would you bother and so forth.

I am looking for technical responces to explain if it can be done and what it would require.

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dangerous_daveo Grand Master

dangerous_daveo

Posted
Posted
Id say part of the reason is the fact that the Silvia turbos dont use ceramic exhaust wheels.

And because of that an RB20 with an S15 turbo wont make the same power??? No one is watching you, you can read the first post a number of times without anyone thining you are daft. But once you hit reply its all over!

Dont the later model SR20s have vvt on them? Would this not help, along with however many extra years of development.

T04GTR Grand Master

T04GTR

Posted
Posted

id say that its because the engines probably abit more eficent. besides a stock 20 turbo is nothing special

also i believe rb20's are alot more suseptable to detonation problems once pushed. so you cant run a whole lot of timing thru them

TTT Grand Master

TTT

Posted
  • Author
Posted

LOL..

I was under the impression that the VVT on the S14 and 15 sr20's were only good for low down grunt.

I just assumed that by using 7psi in stock trim to put out about 100-110rwkw and being able to get that to 220rwkw using same turbo, 2.5 times more boost, and other mods, would the same said mods produce same numbers when used on an Rb20?

I guess I was trying to find out if the S15 turbo when implemented on an RB20, can produce sr20 style numbers.

or is the turbo just designed right for the sr20 and won't do the same on the rb20?

paulr33 Grand Master

paulr33

Posted
Posted

it comes down to displacement and how the engine makes power.

youll also find the sr20's are somewhat less laggier compared to the rb equivalent when talking about turbocharger response. i think they also run split pulse manifold and housing from factory.

discopotato03 Grand Master

discopotato03

Posted
Posted

I reckon if an RB20DET was developed to make the same type power as a std or mild SR20DET it could do it . If it was sized to run out of air and exhaust flow at the same point that is . The thing is who's going to put 9:1 pistons along with porting /cams/ turbo etc to make SR20 type torque for their Skyline ?

You don't need to anyway because an R32 looks much faster parked in the street than any Silvia .....

SirRacer Experienced

SirRacer

Posted
Posted

im going to get flamed for this one but the sr20 is a better engine. it has vvt, a higher compression ratio, heaps more torque so rightfully produces more power. it takes a heap of supporting mods to get a t28bb up to 220rwkws however. (i also own an s14k's so know a little about them)

realistically you would only expect 200kws atw on an sr vvt engine that doesnt have things like exhaust manifold, upgraded afm, cams etc etc

if you think about it the rb26 is nissans flagship 6 cylinder engine whereas the sr is their flagship 4 cylinder engine. building the rb20 better than the sr doesnt make sense from a marketing prospective.

Chris32 Veteran

Chris32

Posted
Posted

I'd say that the RB20 would make a little less power than the SR20, if using a S15 turbo

SR20 has much better head flow, higher comp ratio

RB20 'could' rev more, but not with that turbo, as its very similar to my 2510 and that runs out at 6500rpm. After that it feels flat.

I'd chalk up a win for the SR20

CEF11E Veteran

CEF11E

Posted
Posted

hehe miss the cefiro :sick:

I had 195 with 14psi and 204rwkw with 17psi (never ran that due to ceramic wheel)

but i had a list of supporting mods as long as my arm...

I rate the RB25 as a great turbo have just bolted one to a vg20det and am getting a little more than 200 with it and lots of methanol/water.

sorry off topic :ermm:

I think the RB25 turbo will produce 10rwkw less than the S15 turbo on any given RB20

That is if you did a power run with the rb25 turb, swapped the s15 turbo on with an adapter and did another power run.

smurf80 Experienced

smurf80

Posted
Posted
im going to get flamed for this one but the sr20 is a better engine. it has vvt, a higher compression ratio, heaps more torque so rightfully produces more power. it takes a heap of supporting mods to get a t28bb up to 220rwkws however. (i also own an s14k's so know a little about them)

realistically you would only expect 200kws atw on an sr vvt engine that doesnt have things like exhaust manifold, upgraded afm, cams etc etc

if you think about it the rb26 is nissans flagship 6 cylinder engine whereas the sr is their flagship 4 cylinder engine. building the rb20 better than the sr doesnt make sense from a marketing prospective.

VVT on the S14's and S15's only really help with better fuel economy. The reason a Sr has more torque is because its a over square motor and has a faily big capacity for a 4 banger.

RB20's are notorious for being breathless down low its due to being a small displacement 6 cylinder. I actually believe the CA is a better built motor then the SR. Its internally stronger and shares many similarities to RB26's. There downfall is age though.

My 2 cents

Chris

smurf80 Experienced

smurf80

Posted
Posted
And because of that an RB20 with an S15 turbo wont make the same power??? No one is watching you, you can read the first post a number of times without anyone thining you are daft. But once you hit reply its all over!

Dont the later model SR20s have vvt on them? Would this not help, along with however many extra years of development.

Its called contributing to what you know and learning my friend thats how forums work. Havent you heard the old rule if you dont ask questions and comment you will never know the answer.

dangerous_daveo Grand Master

dangerous_daveo

Posted
Posted
hehe miss the cefiro :sick:

I had 195 with 14psi and 204rwkw with 17psi (never ran that due to ceramic wheel)

but i had a list of supporting mods as long as my arm...

I rate the RB25 as a great turbo have just bolted one to a vg20det and am getting a little more than 200 with it and lots of methanol/water.

sorry off topic :ermm:

I think the RB25 turbo will produce 10rwkw less than the S15 turbo on any given RB20

That is if you did a power run with the rb25 turb, swapped the s15 turbo on with an adapter and did another power run.

So given that, and say the engine is stock internally the RB20s will be older most of the time. There is bugger all in it I would think.

RB30-POWER Mentor

RB30-POWER

Posted
Posted (edited)

You need to remember, turbo sizing and cam specs aside.

The 2L SR20 has the same displacment as the RB20, therefore all things being equal it will have the same total airflow as the RB20.

However the thing you need to remember is that the SR20 only has 4 pistons, so less pistons, less valvetrain componentry, less main bearings all equals less friction and reduced pumping losses.

So its means the SR20 in theory is going to be alot more efficient at making its power, with less places for loss of power to occur.

Thats my 2c anyway...

Edited by RB30-POWER

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