evilbada

iTrader: (14)

I don't think the topic of VE has been covered much.

It may be a good education for everyone.

evilbada

iTrader: (14)

This makes sense.

evilbada

iTrader: (14)

Thanks Eric.

Ludikraut

iTrader: (17)

You guys are overthinking this.

1.) I'd be willing to bet that there are some critical missing facts in the posted link to the 2.3 vs. 2.0 comparison

2.) The main reason that drag Evos use the 2.0 instead of a 2.3 is because of the stock gearing - nobody wants to shift into 5th at the end, so you really want the extra RPM that the 2.0 can supply.

If you look at it from a torque/horsepower perspective, it's the same thing. A 2.3L may make 450 ft/lbs of torque to 7500 RPM, where a 2.0 may make 400 ft/lbs or torque out to 9000 RPM. 450 @ 7500 is 642 HP - 400 @ 9000 is 685 HP

When comparing a 2.3 against a 2.0 you also have to keep in mind the turbo, VE, and boost. For example:
2.3L, 100% VE, 28 psi at 7500 RPM will move ~62 lb/min of air.
By comparison:
2.0L, 100% VE, 28 psi at 7500 RPM will move ~54 lb/min of air.

So, what can we conclude? At the same RPM and VE, the 2.3L should make more power than a 2.0L ... given the same boost/if the turbo can move enough air.

HTH...

l8r)

nitz

iTrader: (3)

i agree that on paper the 2.3 should make more power for a given rpm,boost with no restrictions in VE between the two.
is this what we are seeing repated in reality?
or are those said mechanical losses at higher rpm of the 2.3 really robbing significant power?
unfortunately, most of real world results can't be compared accurately since too many variables exist.
guess we'll have to go with the paper

JordanS4

iTrader: (11)

Yes, however the fact that it (2.0) can achieve a much higher RPM negates the fact that the efficiency of the 2.3 may be higher, since drag Evo's need all the powerband they can get when trying to spool up a 42R. The nature of drag racing is to be in the highest RPM range of the motor. That is the strongpoint of the 2.0 and why drag evo's use them, NOT gearing. Although that plays a factor, the shift into 5th happens on any serious drag car anyways (assuming stock gearing). On paper the 2.3 should move more air but 100% VE is very difficult to achieve and the friction losses do take over at high RPM.

nitz

iTrader: (3)

i know you guys are just trying to indicate an engine running at it's maximum efficiency by saying 100% VE, but remember force inducted engines regularly see VE's greater than 100.

off topic, but wouldn't another major advantage of 2.0 over 2.3 also be the faster rate of rpm increase? i would think less friction due to smaller rod angles, less momentum from lower piston velocity, and shorter piston distances for a single stroke all contribute to an easier and faster revving motor.

scorke

iTrader: (18)

100 percent VE is exceeded by almost any forced induction engine, fwiw....


Scorke

scorke

iTrader: (18)

Scorke

Ludikraut

iTrader: (17)

I don't think that's right. According to my calculations (which, admittedly probably aren't as accurate as they could be), my engine didn't clear 100% VE until I put a better intake manifold on it. IIRC a stock 4g63 is somewhere in the low 90s. I wouldn't even want to guess how crappy my Forester XT's VE is...

l8r)

Ludikraut

iTrader: (17)

Ok, here's the best comparison that I've been able to dig up so far. This pic combines test results from somewhat similar setups:

Runfile_009: Evo 9, AMS 2.3RR, AMS VSR intake, GSC S2 cams, GT35RL
Runfile_013: Evo 9, AMS 2.3RR, AMS VSR intake, GSC S1 cams, GT30R
Runfile_015: Evo 8, AMS blt 2.0L, AMS VSR intake, HKS 280 cams, 50 trim, AMS/Headgames ported head

All tuned by the same tuner (Chris) on 93 Octane, using AEM
All runs on the same dyno
All runs in 3rd gear
All runs SAE corrected




My personal conclusions from this:

1.) There is no point in running a 30R on a 2.3. The 35RL (yeah, it's not even an HTA) doesn't spool much slower than the 30R and absolutely buries it power-wise.

2.) There isn't much point to upgrading to a 2.3L if all you're going to run is a turbo in the 30R/50 trim range. Either engine will max the turbo out, and if you figure that a 2-3 shift at 8500 RPM puts you at ~6000 RPM in the next gear, you're really not gaining much with the 2.3. Yes, the 2.3 will out-muscle the 2.0 at lower RPM, but then I can rev the 2.0 even higher ... so it all comes down to a case-by-case basis: sometimes the 2.0 would be better, sometimes the 2.3

3.) This is a comparison of two heavily modded cars, with the 2.3 setup using the arguably best 2.3L kit out there. A more pedestrian 2.3 would fare worse in the comparison. Unfortunately I don't have a good dyno chart for a regular 2.3 that I can overlay...

l8r)

JordanS4

iTrader: (11)

http://www.kidzuku.com/StrokeOrNot.pdf

Ludikraut

iTrader: (17)

^ yeah, I read that doc last night. IMO it would have been more interesting to see the comparisons done between the 2.3L @ 7500 RPM and the 2.0/2.1 at 8500 RPM.

l8r)

vboy425

iTrader: (19)

yeah but if you comparing at the same RPM the stroker will make more. the reason why 2.1 and 2.0l makes more cause they can rev and peak whp. The stroker is not safe to rev that high due to piston speed and rod angle like a 2.3. AMS 2.3RR is a 2.4 block with some customs stuffs. AMS correct me if i'm wrong. I'm going to buy AMS 2.3RR one of this day You'll get better rod angle just like 2.1 destroke, 2.4L with 2.0L crank and with long rod. rev that **** to the moon.

also i know don't why people call 2.4 a stroker. 2.4 is not a stroker. 2.4l is 2.4 block.

homemade wrx

that's pretty much a given with the difference in rod ratio between the two...I'd also venture to put money on that if both of these were to get built heads and cams on the same turbo the 2.0L would start to work over the 2.3L as it can now take advantage of its flowrate and powerband (I'll start talking rod ratio and its effect on dwell at tdc vs. bdc, as well as effects on ignition timing, combustion pressure, combustion efficiency and VE's in a bit).
That 1.5:1 rod ratio of the 2.3L and the added displacement will always give it faster spool and less top end power than the 2.0L

look at a comparison of the AMS 1000whp SCC article...notice the power and boost levels required between perrea's 2.3L and the shop long rod 2.1L...they are fairly similar setups but the shop car made 962@48psi and the 2.3 made 936 @52....10% (ish) less displacement and 4 fewer psi of pressure making 26 more hp...

now I'm just having fun(as I'm kinda tired at the moment and don't want to make a long response...that and I'm sure Martin can explain it to you as I think he too has a bit of a niche in IC engines engineering )....really the tests you list and the parameters shown can't really be compared to explain why the 2.0L is capping as fast as the 2.3L when it should be happier at high rpms (when compared to the 2.3).