RB20DET vs SR20DET

[funkymonkey]

lol shhh it was meant to scare the kiddies into not saying it as well.

[Cubes]

lol. I thought you were about to pull the mod stick out and wrap it around my clownish arse for a sec there.

haha

[Cool Hand Luke]

I have owned an s13 with both sr and rb.. First i owned the rb, fairly minor mods, ecu, s2 rb25 turbo @16psi, turbo back exhaust, fuel pump, fmic etc. I loved it and the 6cyl does sound great when it revs to 8200! With the ecu done the rb20 pulled from 3500-3700 all the way to the 8200rpm rev limit, so it does have a wider powerband. But you really need to run the 4.3 diff gears to compensate for the high revs. When i owned it i used to bag sr's... unitl i owned one.

Albiet the sr was modified more (had forged pistons and HKS T300 turbo) so its always going to make more power, i was more suprised at how it developed it. The rev limit was set at 7300 but if it was capable would have pulled much further past it, maybe the stock ones dont pull hard but within a few seconds of snatching 2nd and if it didnt wheelspin too much you were on the rev limiter and looking for 3rd. It really pulled hard and the torque difference was noticable. Dont forget that if it makes the same power but revs lower its going to have more torque, and if it doesnt have too short gearing will always be faster accelerating.

The other difference was the handling of the car, the weight difference of the rb was definately noticable. The other things was if you were going to race in the rb, to get a good start you would always have to fan the clutch, where as the sr hit hard straight away. If you dont think torque makes a difference, drive a rb20 and rb25 with 180rwkw and tell me which one you prefer... but this isnt a comparison between the rb25 so it doesnt matter

lol. I thought you were about to pull the mod stick out and wrap it around my clownish arse for a sec there.  

 

haha

[mokompri]

i think you will find the reason why the sr20 starts choking up top is a limitation of its camshafts, something easily fixed...

as for the iron block being stronger then the alloy for more boost, this is a bit of a useless advantage imo, for most people the strength of the sr block is not going to be a problem... not unless your into straight line drag only with mega power, and if so, i wouldnt bother with either engine .... in which case the weight saving of the alloy block would be the better advantage to have imo

also the statement of more cylinders make more power is a real blank one. F1 cars are n/a, with forced induction its a whole different story... more cylinders doesnt necessarily mean more power, especially on turbo'd cars

show me graphs of an rb20 and an sr20 with the same turbo, this will be a good comparison... not based on whether 6 cylinders is better then 4, but rather a direct engine to engine comparison

[funkymonkey]

show me graphs of an rb20 and an sr20 with the same turbo, this will be a good comparison... not based on whether 6 cylinders is better then 4, but rather a direct engine to engine comparison

I dunno.. same turbo in an RB20 will spool up a lot quicker than on an SR... you might need to find turbos for each engine that give the same percentage of improvement. Stock to stock comparison is better I guess.

[Cubes]

The SR's are already running a larger duration and lift cam shaft than the rb20.

Maybe this is why they use a little more fuel?

Does any one know the SR20's valve size?

I need this as I am going to have a little play with a engine dyno simulator.

Do a little comparison.

[yogi000]

Hey guys,

what affect would larger duration cams have on a rb20 or larger lift???

how does it work??? the longer the valve is open the more gas can escape/enter the chamber????

Cheers

George

[Cubes]

Lift vs Duration.

My understanding is duration shifts the power band higher in the rpm.

Lift increases torque and acceleration.

[carl h]

Lift vs Duration.

 

My understanding is duration shifts the power band higher in the rpm.

 

Lift increases torque and acceleration.

i was under the impression that a higher lift allowed for more air flow while duration let more air in per cycle.

isnt it cam timing that will move the power band around or am i talking out of my arse.

[Cubes]

i was under the impression that a higher lift allowed for more air flow while duration let more air in per cycle.

Thats what I said.

Cam timing does also slightly affect the power band.

Higher lift allows more air to enter the pots for the duration.

So a 240duration cam with 10mm lift will allow more air to enter the pots than a 240duration cam with 7.8mm lift.

Therefore the 10mm lift cam will allow more power/torque for the rpm operating range.

Lift does extend the top end to an extent but no where near as much as a large duration cam.

Everything works together.

To gain the best possible power through the rpm operating range a higher lift is always best.

The SR20 has lumpier cams than the rb20t BUT it also has 2 less cylinders.

It has to flow ~8.25% more air per cylinder to match the same airflow of the rb20det.

Obviously the valves are larger so this leaves the cams to make up the rest of the airflow.

[rsx84]

adj cam gears will move the power band up or down the rev range, just this alone on the exhaust cam can increase the torque output slightly on the rb20det..

[discopotato03]

I can't see it happening , but it would be interesting to see what a seriously modified RB20 could do set up for a maximum spread of torque .

By that I mean short timed high lift cams , optimum cam timing , 9 to 1 CR and current type turbos ie GTSS or GT28RS with 10 lbs of boost .

Correct me if I'm wrong but it seems SR20DET's towards the end (S15's) got more sophisticated engine management , and the Garrett GTBB turbo is a far cry from the RB's ceramic sputnick turbocharger .

This may be a little off topic but I think its fair to compare the R32GTST to the S13 with the early fixed valve train and the bush bearing T25G turbo . I believe these were both on sale in Japan in 1989 so its relivant to the era . I have not owned either but have been in both and the R32 was a much more complete package in bog std state . The RB20 was very smooth and progressive in other words easy to drive . This feeling of it won't go down low is silly , what two liter engine thats designed to rev does ? Can you really expect them to pull like a Masey Furgeson (Farm Tractor) at low revs and keep it up to the redline ?

I cant comment on drag race engines because they don't interest me , smooth controllable power curves do . I hate engines where the power all comes in with a bang at half rev range and is impossible to control .

Gary would probably tell you that average power is far superior to top end because of the effect on handling .

In my biased opinion the R32 is a better balenced car with a quite reasonable power curve . The S13 did not have that nice feel and roll free handling poise - probably because of the different weight balence and strut front suspension . The SR20 did not have that "I want to rev forever" feel that is nice in a sports type car . It did not have the feeling that it could be changed down two gears at a time to power out of sharp tight up hill curves from a reasonable clip . There are definatly times when using another thousand revs (or two or three) are preferable to an up change on twisty roads . The SR20 was not a smooth engine when pushed which I put down to heavier pistons and longer stroke .

I think the SR20 was a bean counters jack of all trades , I think the RB series sixes were a more sporting oriented engine and this shows up in the cylinder heads - the twin cam ones anyway .

[VLRB20DET]

I dunno if im on the money with this but from what I have seen/read the RB20's are no where near as responsive to mods as a SR20DET, also turbo sizing is much more researched with the SR20 where as the RB20 turbo sizing is not as easy, Like everyone knows a SR20 and a TO4E is a good combination and delivers alot of HP, where as the RB20, you have the option of using a GT2530 or some of the stock turbo's from rb25 and VG turbo's, although ROY tried out the Trust TD06-20G unit but besides that there isnt many options, I think the SR20 would win in the power stakes easilly....

[TTT]

I think both engines have good and bad points.

however, lets forget about street cars for a second.

as an example, lets look at drag.

Lets look at a 1994 200sx.

lets call him "DEVLSH"

8.9?? still a 2L alloy block.

and that was with the stupid Viscous coupling diff spinning one wheel all the way down the track.

yes that is one example..

GGHOST is another example that ran a 9.something..

2L SR20

someone give me an example of a similar RB20

go on...

[funkymonkey]

er... why on earth would you develop an RB20 for drag when you can use an RB26 or RB25?

The most powerful 4 cylinder Nissan engine is an SR20DET, so you develop that to keep within the requirements of the category it'll have the best advantage in.

The most powerful 6 cylinder Nissan engine is... not an RB20... you gotta be a complete nutter to try and use an engine that's lower spec against engines with higher capacity/power capability in the same category. Its like wanting to use 12A against 13B turbo's and 20B's in the rotary category.

Find a category where an RB20 is advantaged, and we'll develop one for drag use.

[TTT]

the catagory is not my point.

there is a thread in here about rb20's with 250+rwkw.

roy had about what 260rwkw?

how long did it last?

people have got 300+rwkw from SR20's.. why? who cares?

have you come across an RB20 with 300+rwkw?

I haven't..

Like I said.. I'm not bagging it.

I just don't see it being developed like the SR's are.

people just go up the food chain to an RB26... but the rb20 v's SR20 thread here doesn't/shouldn't involve rb26's or 25's for that matter.

in all honesty, the next car I buy will probab;y be a 4 door r32 with an RB20.

which will be stripped and sold once the RB30det is ready anyway so I don't really care for either engine..

I want the torque of the RB30det.

SK's first one he made had 475 hp or something.. can't remember..

he said that the peak power was at 6250rpm (again... I think)

this seems to rev less than the SR and way less than the RB20 but I would still prefer it over both.

I've had an R32 gtst and now have an S14.

I use my car everyday for everything.

and as a street car, the S14/sr20 shits all over the R32/rb20.

It makes no difference that the SR has nothing over 6000rpm because 1st gear to 6000rpm in the S14 will get me just over 60ks anyway and what use is that to me driving to work?

I hate v8 commonwhores and falcon's but want their off the mark torque with no revs.

so the RB30det will be just perfect for me.. even if it only produces 200rwkw.... the torque that it will have at street pace in any gear will keep me happy.

same reason I prefer the sr to the rb... It just seems to be more punchy without having to rev it like the RB.

on a circuit it would probably be a completely different story...

different strokes for different folks.

[funkymonkey]

well the point I was trying to get across is that there's nowhere further up the foodchain than the SR20DET and hence why its so highly tuned in the drag circles, if there was an SR26DETT would you not pick that as a base for a drag car over an SR20DET too?

RB20's are developed to a certain extent in Japan though, because there's a

[MerlinTheHapyPig]

Like I said.. I'm not bagging it.

I just don't see it being developed like the SR's are.

people just go up the food chain to an RB26... but the rb20 v's SR20 thread here doesn't/shouldn't involve rb26's or 25's for that matter.

The reason why, is that rb20det's haven't been in production since 1994. And SR20DETs are still in production, of course they are being developed more. If they still bothered making rb20det's they would have VVT etc. and would provide a fairer comparison.

This is why rb26's and 25s are being mentioned, because they are still in production, and also have more mods avaliable.

the question itself is biased towards the sr20det, because it's still being made, and is avaliable in stock form with 20 more kilowatts and vvt, and not to mention, simply a newer engine, you should only be comparing the s13 sr20det

our of curiousity, how many sr20det red top engines are making 300+kw?

[GTR-Ben]

SR20DET redtops making 300rwkw+... well most of the Big HP SR20DET's are Red top, due to having bigger ports etc.

There is a datto here with a red top making 700HP or so, doing low 8's.

The title was RB20DET vs SR20DET.. not stating year etc. Obviouslly the SR20DET wins in the 2L vs 2L comparison.

[Sydneykid]

someone give me an example of a similar RB20

go on...

Zeni Tani RB20 powered R32 GTST, registered road car, no nitrous, standard RB manual gearbox (synchro, H pattern) on road radials did 9.9 at the HKS drag meeting last year. Stick some nitrous in it, take off 300 kgs, add drag slicks, whack in an auto and it would do 8's on its ear...... :wassup:

Not everyone cares about 8 miserably short seconds, personally I prefer several minutes of the RB20DET powered Gibson R31 GTSR in the rain with Glen Seton driving. Now that's throttle control, only made possible by the RB20's superior power band.