Turbo Theory and Selection...why the 14b ain't bad

[mtnickel]

A little rant i had. Take it however you like...just an opinion from 2 years of turbo research and talking to people and real world results.

The 14b is absolutely fine and Very well suited to this engine. Even at Redline, you're still inside the efficiency map.
And to boot, our engines redline (6200+RPM) will drop way off on the Volumetric efficiency, so it's pretty much taking in as much air as it is at 5500-5900rpm (max power).

Doing the math...

5800rpm *CI (132) * 90% VE(optimistic) /2 /1728 *1.61 PR (1 +9psi/14.7) = 322CFM

322CFM / 14.55 CFM / lbs/min = 22.1LBS/min = ~221HP (some say wheel, some say crank Regarding 1lbs/min of air = 10hp) considering all the dynos at various PSI, 205whp is probably pretty close for stock boost.

So, lets look where 322 CFM comes in on the efficiency map, also note there will be some pressure drop across your IC and IC piping....a realistic turbo PR would be around 1.7 (alhtough the manifold is at 1.6).




Still near 68% efficient...more than enough.


and the DSM world put out nearly 260-270whp on these turbos...regardless of PSI, the choke limit is gonna be about the same no matter the PR.

with any decent FMIC at near 70% efficiency, you can run this turbo probably out to around 60% efficiency...intake temps will only be about 8deg higher than a similar turbo at 70% efficiency.

Extrapolating that info on the graph above...you can see that at 60% efficiency, about 375CFM (about 220whp @ 1.7pr (9psi)), or about 420CFM at 11-12psi (what i may run) = about 245whp @ 1.9pr. Of course the DSM guys push some 20-22psi on these things and if you look on the map, near 60-55% efficiency, and about a 2.5PR, this turbo can potentially push out around 480CFM = 280whp.
that said, i think with a solid big FMIC you could reach even higher at these boost levels...running efficiency into the 50's isn't going to increase the Intake temps much at all with a 70% efficient intercooler. I'd say 240whp is attainable at 9psi and 265whp at 11-12psi...with accompanied mods that woudl support this flow at these PR's.

There are calculators of intake temps with certain Turbo efficiencies and Intercooler efficiencies, and we are really splitting hairs running a t3/t4 over a 14b at low boost levels.

You gotta at least come close to maxing out the turbo you're using.
Hell for a torque monster and instant spooling, the T25 would pull pretty damn hard at 8psi and make 190whp no problem...not bad at all.

Just ranting on turbo sizing...not sure how many have done all the math or not.

[mtnickel]

if money is no object, the T3 60, T3 Super 60, Small 16g, and EVOe 16g are all marginally better...

But, for any setup running on a stock bottom end...this turbo should be more than enough for 90% of you...unless you are crazy like Straightedge or MRX or other guys who are very good tuners or know good tuners and might not mind swapping an engine out.

If our engines had knock sensors i'd probably run closer to 270-280whp, but we don't so i keep it in a "SAFER" (not safe) area.

Mark

[chessboxer]

good write up man, and im not far enough into the turbo world to argue with you, so no negative comments here.

[c mak]

Wow. that was the best writeup on the 14B that i have ever read. it all makes perfect sense now. i had no idea that you could calculate everything like that. i was still kind of skeptical about putting the 14B on my car, but now i am more confident that it really wont be too small and it will work pretty efficiently. thanks again Mark! Later-craig

[mtnickel]

what really made me laugh all the time, was statements like...
"past 5500rpm the 14b just blows hot air"

The thing is, that's just a characteristic of how our engines flow...how much does your car pull from 5500-6500 (no DOHC users here)...our SOHC's naturally fall off in power. The power with the turbo on is no different, it follows the VE of the engine and the power curve remains somewhat close. (torque shifts do occur somewhat, but not to the point that you make AWESOME power till redline)

Mark

[d112crzy]

The thing is, that's just a characteristic of how our engines flow...how much does your car pull from 5500-6500 (no DOHC users here)...

damn.


You should do some research on stock honda knock sensors.

They blow ass, completely. You cannot by the life of anything get good readings from them.

If you want something to monitor knock, then either buy yourself those expensive ass knock sensors or build yourself some DET cans.


Also, I will add from what I said in the other thread.

Not everyone likes instant boost. A lot of people(including me) that say the 14b sucks is for that very reason. I don't want to be spooling or see any boost while I'm riding around the city.

[Accord R33]

You can do all the fancy math you want. until you have driven a car with the 14b, you know nothing about it.

The power is ok, but it sure as hell doesnt last anywhere near redline. It dies off pretty quick after 5k.

for the price difference between the 14b and the 16g, there is no reason anyone who is serious about the power and reliability of their car should choose the 14b

[mtnickel]

You can do all the fancy math you want. until you have driven a car with the 14b, you know nothing about it.

The power is ok, but it sure as hell doesn't last anywhere near redline. It dies off pretty quick after 5k.

for the price difference between the 14b and the 16g, there is no reason anyone who is serious about the power and reliability of their car should choose the 14b

Again...you say the power doesn't last till redline...even when i drive my car NA, it doesn't last nearly till redline...i always shift at 5500-5800rpm.

The engine from the factory makes maximum power at 5200rpm (the A1 anyways). The volumetric efficiency is just suited that way, such that the power does indeed drop off past 5200rpm.

And i think you're exagerating a bit here too...just look at your own dynograph...

http://www.homemadeturbo.com/forum/i...7932#msg377932

made peak power right at 5200rpm (like stock), and still made 180whp to redline...i guarantee if you dyno'd without the turbo you'd see the same 9% drop past peak power.

unless you're boost is rolling off, or you measure insanely high INtake temps only past 5000rpm (which i highly doubt), then it is just as it should be.

mark

[chessboxer]

noob question time.
how much does a more aggressive cam that is better suited for high end power like a delta 272 change the power curve of the engine? i understand it helps out up top, but as for power falling off and such, how much of a difference does that make in combination with the turbo and such. i havent dynoed yet so i cant show my results, but id like to see how the results line up with what everyone says.
i expect good things, but my hopes are high and anything will be better than the clutch slipping excuse of a car i was driving pre turbo.

[Accord R33]

What the car performes like pre-turbo has absolutely nothing to do with anything.

The fact of the matter is: For not much more money you can get better, safer power than that of the 14b.

[prNonVtec4u]

damn do i love this thread

[F22Turbo702]

Ok ok...yeah, the 14b is a decent turbo, if I were a Honda engineer and had to pick a turbo to put on a stock Honda motor, that would be my pick for something in the 1.6-1.8L range, however, as an enthusiast looking for a good street turbo car, it is most certainly not the turbo I would pick.

Of course, the smaller the turbo the quicker the spool time, but a quick spool is worthless if the turbo doesn't even provide power to redline, this of course does have to do with the cam as well, but even with a T3 turbo, the motor will still pull past 5500rpm. Now, I understand that the stock motor doesn't provide good power all the way to redline, but isn't that why we tune our cars? Aren't we here to find paths to better VE?

I personally think a Garrett .42/.48 from a Volvo or Ford Turbo Coupe/Mustang SVO is a better match if we're talking cheap, readily available junkyard/rebuilt turbos for the budget minded tuner. Hell, even a T25 or T28 is a better suited turbo, and will provide power to redline with the proper cam.

Also, I would like to add that the quicker the spool, the more gradual the torque output, hence the slower the car, especially if the turbo drops out of the 70+% efficiency zone.

Although you're math is correct, I believe that your argument is inherently flawed. The whole point of this game is efficiency, and if efficiency is not your goal, well, you should probably just leave well-enough alone. Lack of effieciency and high intake temps blow motors even on the best tunes, the 14b is only really efficient until about 190whp, after that, you're better off saving yourself the expense of a new motor and going with a properly sized turbo, especially for someone on a budget.

I hope you take this as constructive critisism and not a personal attack, at least you took the time to do some math and come up with your own thoughts on the matter. I know a lot of people are using the 14b with great success on low psi, budget setups, I still don't think it's properly sized by any stretch of the imagination.

Just my humble opinions.

-Kyle

[mtnickel]

What the car performes like pre-turbo has absolutely nothing to do with anything.

The fact of the matter is: For not much more money you can get better, safer power than that of the 14b.

How do you figure the volumetric efficiency will have nothing to do with anything? An engines ability to take in and push out air has a lot to do with it.

Of course the the exhaust manifold and turbine/turbine wheel will affect the VE, and usually in a negative way. More pumping loss and less efficiency. This is why if you run your car with a turbo on it, but with the wastegate wide open, it's gonna have at least 5% less HP then with a properly sized header.

And as far as safer power...intake temps aren't really much different at all from a 58% efficient turbo to a 70% efficient turbo. (provided you have a good intercooler)...Post turbo, there is a 25deg difference (@ 10psi), but with any decent IC, post intercooler differences are... 9 degrees. That's with a 65% efficient IC whereas a 70-75 can be attainable with our front mount location.

So all in all, these intake temp differences are really splitting hairs...so where you get the "major power drop off" is news to me.

I haven't really seen anyone actually try and push the 14b on our setups...they usually upgrade first..but pushing it to 12psi or so would probably yield good results if you ask me.

I'll have to do some more research, and "real world testing" as you say, but there is certainly a good argument for the 14b given it's proven capabilities elsewhere.

[Accord R33]

your looking into this way to deep.

trust me, i know all about the math and physics involved in a turbo system, i was once in the same position you are, iv been through countless sleepless nights just learning how all this works, and without sounding big headed, i feel i have a pretty damn good grasp on it.

im not sure what your exactly trying to prove here. That the 14b isnt a bad turbo? ok, thats been proven time and again, its a great turbo for what it is, but there are more factors involved that what the turbo looks like on paper, most importantly, the price and physical condition of the turbo. low milage 14bs, in decent shape, are far and few between. and the good ones are close in price to the 16g!

[mtnickel]

well i've seen 14b's with 120k miles on them and still in excellent condition.

Here i can get them for around 100-130us in good condition, and around 75us needing a rebuild...with rebuild kits at $80us...you still hvae a new condition turbo for around 160us.

Most 16g's i see are at least 300us in good condition, and rebuild ones still want to fetch 250.

Mark