What to do with R32 GTST RB20DET to get it into the low 12s in the 1/4 mile (400m)

[Daemos]

So I was debating weither to get a 180SX w/CA18DET or a R32 GTST w/RB20DET

Now I have set performance goals for the cars.

For the engine, I want it to get the car in the 1/4 mile (400m) in the low 12s high 11 range.

Although this will NOT be a drag car, it'll be more of a daily driver with autox focus. but I still want it to beable to fly down the 1/4 mile

[N I B]

We have done 11.9 in an R32 GTS with a Hiflow turbo, Intercooler, exhaust, fuel reg and S-AFC,That easy and this car runs tru street tyres.

[beario]

gees steve-sst thats an impresive 1/4 time for the mods you have,can you pm me with more details,i/e the turbo etc etc as i have yhe same car and want to get a front mount and a turbo real soon,where did you get the turbo,what make,how much etc etc any info would be much appreiciated,cheers

[rbs13]

yea. post that up here steve.. and i guess they are nittos? what size etc if they are or not.. im interested in knowing about the car too!!!

[N I B]

will try find the specs of the turbo but you need around 340rwhp.

[Daemos]

and is that using the RB20DET and not the RB25DE?

[CGB_R32]

Steve - SST you've done those mods without a fuel pump or bigger injectors and all the other support systems that have to be upgraded with bigger horsepower?

[ABuSD]

Was the car stripped of everything so it weighed 150kgs less?

Great time tho!

[red17]

I think it has a 5" pro-comp bullshit meter too

[neil_se]

Back to the original question, i'd definately take the r32 over a ca 180sx to get into the low 12s. The rb20det will get there on stock internals whereas the ca18det won't. That's why i've swapped my ca18det for an rb20det in my 180sx, i'm aiming for mid to high 12s. Alternatively if you like the shape of the 180 more, just get an sr20det one and it will have the same potential as an rb20det.

[Sydneykid]

Back to the original question, i'd definately take the r32 over a ca 180sx to get into the low 12s. The rb20det will get there on stock internals whereas the ca18det won't. That's why i've swapped my ca18det for an rb20det in my 180sx, i'm aiming for mid to high 12s. Alternatively if you like the shape of the 180 more, just get an sr20det one and it will have the same potential as an rb20det.

Hi Nei, a standard SR20 will never rev as well as a standard RB20. Those spindly rockers will not handle the rpm like the cam on bucket design of an RB.

Since horsepower = torque X rpm , you should always be able to get more horsepower out of an internally standard RB20 than an internally standard SR20 given the same amount of money spent.

I also respectfully suggest that you remember that CA's are cam on bucket, the same as RB's, so they rev far better than SR20's as well. It's a lot easier to toughen up the bottom end of a CA, than it is to fix the inherent design flaws in SR cam and valve operation.

Hope that clarifies

[neil_se]

I think you took my 'same potential' a little too literally. I'm talking generally, eg. a hks 2530, fmic, exhaust, etc on an sr20det and rb20det will both produce around 220-230rwkw. Both stock internals are thought to be reliable to around 250rwkw but can also be tuned to around 300rwkw safely. I haven't seen anyone pull near these figures on an internally stock ca18det.

[Sydneykid]

Hi Neil, if I had none of 3 engines and wanted to make 300 rwkw. So I had to buy them from scratch, I would choose the RB20 first, CA18 second and SR20 third based on the amount of money I would have to spend and the inherent strength (and therefore longevity) of the engine.

As well as the engines themselves (SR20's being the most expensive) I would have to buy pistons for all three. Plus conrods for the CA and the SR. The cost of fixing the SR's inherent valve train issues would cost far more than a forged stroker (2 litre) crank for the CA. Using new parts, I reckon the RB wins with the CA second and the SR third.

If you go second hand, there are some stonking 2 litre CA's for sale in Japan for the cost of the turbo and manifolds.

[neil_se]

I think you're talking a little beyond the scope of the question Sydneykid, he's only after low 12's/ high 11's which i would have thought would require between 250-270rwkw. Therefore the sr and rb would not require internals (wouldn't sr internals work out cheaper anyway? 4 of everything cf 6?) or valve train modifications. The cost of the engine itself rb and sr would not matter with my suggestion since an sr20det 180sx and an rb20det r32 will cost about the same.

Also, since HP=torque x rpm wouldn't agree that the sr20det has more torque? Factory figures would suggest so, as would every person i've talked to who has owned both. Peak power will occur below the max rpm on both engines so the fact that the rb20det will withstand higher rpms is irrelevant to peak hp? I'm not arguing, i'm genuinely asking.

[Sydneykid]

I think you're talking a little beyond the scope of the question Sydneykid, he's only after low 12's/ high 11's which i would have thought would require between 250-270rwkw. Therefore the sr and rb would not require internals (wouldn't sr internals work out cheaper anyway? 4 of everything cf 6?) or valve train modifications. The cost of the engine itself rb and sr would not matter with my suggestion since an sr20det 180sx and an rb20det r32 will cost about the same.  

Also, since HP=torque x rpm wouldn't agree that the sr20det has more torque? Factory figures would suggest so, as would every person i've talked to who has owned both. Peak power will occur below the max rpm on both engines so the fact that the rb20det will withstand higher rpms is irrelevant to peak hp? I'm not arguing, i'm genuinely asking.

Hi Neil, Let me try and answer, one by one....

Unless you get seriously into lightweighting, consistent high 11's are 300 rwkw territory.

An RB20 with pistons and rod bolts (and all of the other necessary bolt on stuff) will make 300 rwkw at around 8,750 rpm. It will rev to 9,000 rpm, so you are right "peak power will occur below the max rpm".

Standard SR20 rods won't make 300 rwkw, so you need those and they won't rev to 8,750 rpm with the standard valve train, lucky to make 8,250 rpm consistently. You need more torque to enable a lower RPM limit and still make the power. So you end up with the need for a bigger turbo/higher airlfow/more boost. This puts more combustion pressure on the rods. That's why you need forged rods in an SR.

A CA top end (being basically the same as an RB's) will easily handle 9,000 rpm, so a 2 litre one will do 300 rwkw easier than a SR20.

Lastly, "wouldn't (you) agree that the sr20det has more torque" . I would say no, not until you run a bigger turbo/higher airlfow/more boost. And you have to do that because they don't rev as high. The fact that a standard SR20 produces a poofteenth more torque (256 nm's) than standard RB20 (250 nm's) is irrelevant once you start modifying them.

I won't get into the alloy block versus cast iron block here, but that should not be overlooked as an advantage for the RB's and CA's.

Hope that clarifies

[neil_se]

Unless you get seriously into lightweighting, consistent high 11's are 300 rwkw territory.

I think that clarifies a lot of the points then. I would suggest Daemos does some lightening, pineapples, suspension, tyres before the major step of upgrading the internals assuming he's on a limited budget like most of us.

Standard SR20 rods won't make 300 rwkw

I hate it when people use one example to make a point, but a mate's sr20det s13 silvia made 290 odd rwkw on stock internals (read: completely stock, no head gasket, cams, cam gears, pistons) with a TD07 on 20psi. Now makes slightly less with a lot less lag.

wouldn't (you) agree that the sr20det has more torque

I still stand by this statement. We have the rb vs sr argument too damn often on NS and a number of members including friends of mine have had both sr20det and rb20det silvias/180s. Never once has someone said that their stock or modified rb has had more torque than the sr.

To quote _omg: "Torque is how much work an engine exerts on a single revolution. With all else equal a longer stroke engine will have more torque than the shorter one. This is simply because the piston will move downwards on the power stroke longer so it has more opportunity to deliver this work to the crankshaft before it is turned around and heads up on the exhaust stroke." rb stroke = 70mm, sr stroke = 86mm

[Sydneykid]

To quote _omg: "Torque is how much work an engine exerts on a single revolution. With all else equal a longer stroke engine will have more torque than the shorter one. This is simply because the piston will move downwards on the power stroke longer so it has more opportunity to deliver this work to the crankshaft before it is turned around and heads up on the exhaust stroke." rb stroke = 70mm, sr stroke = 86mm

Hi Neil, that's too simple....

Think about this;

86 (stroke) X 4 (cylinders) / 2 (4 stroke) = 172

69.7 (stroke) X 6 (cylinders) / 2 (4 stroke) = 209

If what you were saying was true, then an RB30 would have less torque than a SR20 because it only has an 85 mm stroke compared to the SR20 with 86 mm. And we all know that's not the case.

The truth is 2 litres is 2 litres, whether it has 6 or 4 cylinders makes far less difference than how it is tuned. And in our case how much airflow and boost it has.

This is a fun thread, your turn...........

[neil_se]

86 (stroke) X 4 (cylinders) / 2 (4 stroke) = 172

69.7 (stroke) X 6 (cylinders) / 2 (4 stroke) = 209

But wouldn't a formula for calculating torque take into account the displacement? Each cylinder is going to exert a smaller force to cause that stroke on an rb because the capacity is divided between 6 cyl instead of 4. Comparing to an RB30 would be way off because you'd have to take that each cylinder is going to be able to exert a much greater force because of the larger displacement.

Its just not coming together for me, there's a hole in my thinking which i'm sure you'll point out :slap:

The truth is 2 litres is 2 litres, whether it has 6 or 4 cylinders makes far less difference than how it is tuned. And in our case how much airflow and boost it has.

Precisely

Anyway, i'll have a head-to-head rb20det and sr20det comparison in a few weeks. A mate and I both have 180sx's with hks2530's, 3" dump/front, apexi n1 catbacks, fmic, ebc, upgraded injectors, larger fuel pumps, stock internals, etc and both will be tuned at the same boost (probably by the same person) so i'll put up the torque and power figures for interests sake.

[jazza08]

Well that was funny to read..

If it was an sr20det 180sx id go for that without thinkin twice if u want a quicker car.

If it was a ca18det 180sx or a rb20det r32 id go for the r32.

The only other thing i picked up was r32s make 250ish nm and the sr20det doesnt make 256nm it makes a much bigger figure in 274nm, which is closer to the r33 (295nm) so there is a fair bit more torque in the sr20det. Once modifiyin heavily i duno how this will affect things, i would of thought good, but i wouldnt kno for sure, so ill leave the arguin to the two boyz above lol

Jaz

[dog_mongrel]

sr20det's have more torque than rb20s, which is one of the reasons that they are sometimes replaced in r32s, cefiros etc