What has greater power range

[pboglio]

Directly quote out of Desktop Dyno by Larry Atherton, pg 49:

".....In that test, we compared identical displacement engines of 603 cubic inches, one with a 6-inch stroke (dotted lines on graph) to one with a 3-inch stroke (solid lines). Both engines used the same size valves and the same 780 cfm induction flow capacity. As previously demonstrated, the increase in horsepower from the shorter-stroke engine is due to a reduction in bore-wall friction, adding about 100 horsepower at 5500 rpm..........As can be seen in our simulation, bore-wall friction becomes a substantial power robber. Ring seal also becomes a serious problem. As the stroke increases, higher and higher piston speeds cause the rings to "flutter against the cylinderwalls decreasing their sealing ability."

Regarding induction flow, pg 48:

"....At this point, the long stroke has accelerated the piston to very high speeds that generate a strong pressure drop in the cylinder. It is "claimed" that this low pressure drop generates flow velocities so high that the cylinder heads, valves, and the induction system becomes a significant restriction to flow. The rapid buildup in flow and high peak flow rates lower pumping efficiency, and the overall picture gets worse as engine speed and piston speed increase."

Its a pretty good book, maybe it applies to DSM's maybe it doesn't. I considered a stroker on my DSM, but I decided to get an STi instead. Not quite the low end torque of a stroker, but I have more midrange torque than any DSM stroker could possibly make, with all the high rpm torque of a short stroke motor and none of the long stroke rpm rev limitations. I personally vote for a large bore short stroke motor if it were physically possible on a DSM, it'd be the best of both worlds

 

[Slippi84]

Well excuse me for thinking that I can just stare at my motor LONG ENOUGH that it will MAGICALLY APPEAR AS A STROKER. WTF are you smoking. When you build a stroker, theres no extra, EXTRA aftermarket parts you are required. And for the ####ing record its RODS and PISTONS to help your little 2.0's get that high as well, their the same ####ing motor GAWD. If you go do the math, a stroker is not ANY MORE than a 2.0 in any shape or form, maybe machine work.

Cause I'd really like to know what else your buying for 3grand after dropping in your bottom end. I know mine didn't cost that much.

The absolutely only reason not all the gawd awful fastest DSM's are 2.3's, is because their isnt a BIG ENOUGH aftermarket for them to persue and max out that setup next.

Look how long it took FP to make FP3's and 4's. And just look at the dyno results, their huge.

Remember guys, the goal of this discussion from the damn begining was power, NOT RPM's. RPMS != HP
HP = ( Torque X RPM ) / 5252

The title says which has a wider power band and I think powerband is refering to rpms so how can you say it's not about rpms

Listen to the people that are saying that using the fastest guys isn't a indication of anything lets first get a grip on what kinda car we're talkin about here. Of course if you have a car that will almost never see the strip then of course a stroker is better because rarely will you see 8k+ drivin on the street. BUT if you want a car that double dutty you have to look at the strip aspect of the car and that means takin rev limit and shift points into consideration as you guys are just lookin at reving high as something you do for shits and gigles you know how much it affects your times having to shift. If you can rev higher and eliminate a shift that you would have to take in a stroker car that will make up for that little bit more air your flowing as I hate to break it to you guys none of us make enough power to see 100hp more out of doing a 2.3 or 2.4 sway it just aint happening.

Bottom line stroker bad ass street car and good strip setup

2.0 good street setup great strip setup

 

[turbodagain]

You can sum it up at this,

Street car Stroker would be better
All out hp with no concern for low end torque go for the 2.0

 

[Turbocharged]

Directly quote out of Desktop Dyno by Larry Atherton, pg 49:

".....In that test, we compared identical displacement engines of 603 cubic inches, one with a 6-inch stroke (dotted lines on graph) to one with a 3-inch stroke (solid lines).

The key is "identical displacement". What happens when one motor has 20% more displacement?

 

[pboglio]

Sorry, that's wrong. What I see on the "simulation", is that when the Mitsu 2.0 liter short stroke and the Mitsu 2.4 liter long stroke run the same cams, the torque crossover starts at 5500 rpm and the 2.0 liter pulls a consistent 40 lb-ft of torque at anything above and beyond 6000 rpm. This is on a 17 psi 300 h.p. setup.

I assume the stroker could just up the ante and run bigger cams above and beyond the 2.0 liter, which I simulated and it does gain a slight amount over the 2.0 Liter in that scenario, say going from HKS 264/264 to HKS 272/272 cams. But then dropping those same bigger cams into the 2.0, the 2.0 kicks the strokers ass again on the high end, surpassing the stroker right around 5500 rpm.

However, the stroker could always run that much bigger of a turbo, and that much higher lift/duration cams then a 2.0 Liter and get away with it so to speak, and make all the high rpm power back and then some, and still kill the 2.0L in the lowend midrange.

Driveability issues out the window the 2.0 Liter is winning everytime, simulated of course This jives with reality since most street guys are going to strokers, and most serious racers are sticking with short stroke engines. Food for thought.

 

[steel_3d]

pboglio, would you be willing to run the simulation on the 2.0 4g63, just increase its stroke to 100mm? I'm trying to rule out any other changes involved in loading in a 4g64 file or whatever you're using to compare. I'm tempted to buy Desktop Dyno cause it's so damn cheap, but I'll do even less work at work and that's not what I need right now

 

[pboglio]

Weird. Ran a stock 3.35" bore/3.46" stroke 2.0 motor against a phony 3.15" bore/3.94" stroke 2.0L stroker motor. Results, stocker had maybe a 5 ft-lb advantage at higher rpm on the same setup, almost but not quite identical curves. My guess is the extra stroke distance & higher piston speed would normally create higher friction on the stroker, but because of the same engine displacement requirement in this test, the bore diameter got smaller, along with the piston ring circumference and piston ring/cylinder wall contact area, possibly reducing the friction back down for a near wash.

 

[steel_3d]

What's the verdict for a 3.35" bore/3.46" stroke 2.0 vs a 3.35" bore/3.94" stroke "2.3L"? Same everything. In the first test you quoted, you said you used a complete different 2.4 engine model, so I'd like to keep things straight. Same everything, just longer stroke. It does make sense that the friction decreases for the smaller bore, and presumably the reciprocating mass as well.

 

[silkcity100]

best power range setup is a gt35r with a 2.4 with stage 4 cams

 

[Slippi84]

best power range setup is a gt35r with a 2.4 with stage 4 cams

How bout some info to back this up instead of a incredibly wide open answer

A 50 trim on a stock 2.0 with 272's would have the same size powerband as the setup you just stated just it would be lower in the rpm range. Having a wide powerband is relative. Where do you want the powerband to be. You can have a 16g with cams and a good setup pull from like 3200 to redline 7500 which is actualy better than most of the turbos we chose to run but that doesn't make it faster then a gt35r which might only pull from 4500 to say 8k

 

[silkcity100]

BIG 16g is only good for about 350whp,not even close to a gt35r,im almost done with that setup only have the wastegate and boost controller to hook up,i just emailed sean ivey to setup a time to dyno tune it nxt week hopefully,i will post my setup with dyno plots when they are available

 

[Slippi84]

BIG 16g is only good for about 350whp,not even close to a gt35r,im almost done with that setup only have the wastegate and boost controller to hook up,i just emailed sean ivey to setup a time to dyno tune it nxt week hopefully,i will post my setup with dyno plots when they are available

16g will get you into the 11's but that's not the point of my post I was just pointing out that debating over what has a wider powerband is irrelevent without hp goals and where your lookin to operate your car at rpm wise.

 

[silkcity100]

gt35r is good for 600 to 650hp,with a good setup and tuning with a 2.4 , cams,crower springs n retainers, , you should hit 25lbs of boost around 4000rpm and redline at 8000rpm,thats my setup ,whats your thoughts

 

[Slippi84]

gt35r is good for 600 to 650hp,with a good setup and tuning with a 2.4 , cams,crower springs n retainers, , you should hit 25lbs of boost around 4000rpm and redline at 8000rpm,thats my setup ,whats your thoughts

I think that getting 650whp out of a gt35r is gonna be tuff even though it is capable of it that is just about maxing it out and it will take a veryyyyy good tune but it's doable. I think if your trying to make that kinda power you shouldn't be worried about powerband cause the car will be a PITA to dd. Running a turbo like that on your dd is like running a huge v8 your gonna be filling up on gas like every day and I don't knwo about you but gas is crazy expensive where I live. I would look into a fp3575 and a stroker if 600+hp is your goal

 

[silkcity100]

its not my dd,looking for about 550 to 600whp ,it shouldnt be that hard with the 2.4 and every available mod,you live in jersey can you tune a aem ems

 

[Turbocharged]

If you stay off boost, your gas mileage will be fine. I make just under 400 hp on my 2.4 street setup and get 22-25 mpg.

 

[Slippi84]

its not my dd,looking for about 550 to 600whp ,it shouldnt be that hard with the 2.4 and every available mod,you live in jersey can you tune a aem ems

No I never had the need to mess with EMS yet I just use dsmlink. Have you bought EMS yet if you haven't you should consider the link instead cause if 550-600whp is your goal with cams smim ect.. with a gt35r then you should be good with dsmlink. 650whp is a little stretching it as the turbo maxes out at 65lbs/min(usualy about 100hp per 10 lbs/min)

 

[Slippi84]

If you stay off boost, your gas mileage will be fine. I make just under 400 hp on my 2.4 street setup and get 22-25 mpg.

under 400 and 550 600whp are a bit diffrent though

 

[silkcity100]

yeh bought it last year ,this is a long project ,almost done again

 

[Turbocharged]

under 400 and 550 600whp are a bit diffrent though

My point was if you stay away from making airflow that puts you in the higher enrichment fuel maps during your daily driving, you can easily achieve 20+ mpg. A turbo like a gt35r isnt going to flow huge amounts of air under daily driving conditions.

 

[Slippi84]

My point was if you stay away from making airflow that puts you in the higher enrichment fuel maps during your daily driving, you can easily achieve 20+ mpg. A turbo like a gt35r isnt going to flow huge amounts of air under daily driving conditions.

Your 50 trim is a little diffrent than a turbo this size though

 

[speedy13]

wow, my eyes are bleeding. I just read all 3 pages. great posts guys. i agree with the majority. stroker for street,2.0 for high rpm aplications. just my opinion though.

 

[steel_3d]

I've come to the reslization that... I was wrong all along

We were double counting when we said the stroker will have 20% more pressure on the piston (form the 20% increased volume) in addition to the 13.6% increase in torque from the longer crank lever arm.

In fact, cramming 20% more air into a 20% larger cylinder will yield the same cylinder pressure. The ideal gas law states that PV=nRT. So increasing the volume (V) by 20%, and increasing the mass of gas (n) in that volume by 20%, you end up with the same pressure.

Now, whether you'll get 20% more air in the 20% larger cylinder at any given rpm depends on volumetric efficiency. The peak of the stroker's VE curve happens earlier in the rev range, than on a 2.0. So let's say at 3500rpm the stroker will actually ingest let's say 30% more air than a 2.0, raising the cylinder pressure by P = (1.3n)RT/(1.2V) = (1.08P). Multiplying the 8% higher pressure on the piston by 13.6% longer lever arm we get 23% higher torque and hp than the 2.0. But at 7000rpm the stroker will be lower in its VE curve than the 2.0, taking in let's say 5% more air than a 2.0, and you can see that it will make less torque and therefore less power. P = (1.05n)RT/(1.2V) = (0.875P) and 0.875*1.136 = 0.994 so the stroker loses by 0.6%. Note that the stroker can NEVER actually take in LESS air at a given rpm than its short-stroke brother, however it can still lose enough on cylinder pressure to offset the leverage advantage. This is the part we have been missing.

Note that my previous argument about the power band hinged on the stroker making 20% more torque than the 2.0 everywhere in its rev range. Now we see that it does not, and given that its rev range is limited, it will end up with less power under the curve under the conditions I used before (8.8k rpm band for the stroker and 10k for the 2.0). And this doesn't take into account the effects of friction (we don't know how relevant that really is, but I have a feeling that the drop in VE and therefore cylinder pressure has a lot to do with the fact that the stroker lost in pboglio's simulation).

Basically if you can find cams that will keep the VE of the stroker up as long as possible, and rev it high, you might break even or beat the 2.0. But things are not looking as rosy as they used to when we were double counting our chickens

[EDIT] Actually, the redline of the stroker is theoretically not that much lower than the 2.0's, see <a href="http://www.dsmtuners.com/forums/showpost.php?p=50445180&postcount=105">Post #105</a>.

 

[talon96tsi]

Oh dear god, now my eyes are bleeding... build a 2.0 with some good hardware and a strong head, and rev it to 9000.

My .02

 

[steel_3d]

hakcenter, that's what I was saying. Cams will help the stroker. Whether they will help it beat the 2.0, I don't know. It's not guaranteed. You can put stage 4 or stage 16 cams in a stroker and gain power, but you put the same cam in a 2.0, and you'll also gain power, just higher in the rev range. How much, I don't know. Depends how high you're willing to rev the 2.0. The 2.0 has the same airflow demands as the stroker, just 15-20% higher in the rev range (proportional to the actual displacement difference). The whole VE curve is shifted up by that amount. There's a little difference in the piston speed profile, I'm not sure how much that affects things. There's no way you can analyze that kinda stuff in your head (that's why I got Desktop Dyno coming in the mail ).

That's why I was keeping all variables constant except for the stroke earlier in the discussion. It's a theoretical discussion. I used to think the stroker couldn't lose on an even playing field, now I know better.

The key is that the cylinder pressure in the stroker is NOT higher than in the 2.0 at a given rpm. It's less than or equal any time after the 2.0's VE peak, unless given an unfair advantage with cams, intake, exhaust, etc. Its longer lever arm is offset by the lower rev limit, negating its advantage in area under the curve.

Will this make me change my build to a 2.0? Hell no. But I'm building a street car. I just wanna keep the facts straight for the original poster. I'm sorry I was stating false information before, but that's why we have discussions - to learn. I wish someone had corrected me earlier