Honda / Acura K20a K24a Engine Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
81 Posts
Discussion Starter #1
am i the only one who is thinking about putting weber sidedrafts on a k20. i m not sure if it would simplify anything or not. Just need crank trigger,ignition system, and a way to activate vtec. Vtc would be locked out of course. it obviously won t be seeing much street duty, but better atomization with higher compression along with the fact that the joule-thompson effect allows for lower intake temps which eventually leads to more power over fuel injection kinda makes it tempting. It was just a thought i wanted to share
 

·
Registered
Joined
·
81 Posts
Discussion Starter #3
uh the drivability part i agree with, but i also said it won t be seeing much street duty....more power with properly tuned fuel injection...NO

Remember a carburetor is an atomization/emulsion machine. An injection system is a proper air to fuel delivery ratio machine. Two different concepts. If a carburetor can be designed to supply the perfect air to fuel ratio all the time it should consistently outperform EFI. Its design lends itself to have an unfair advantage in atomization.
Obviously adiabatic expansion is the next question on the list. So if we take a good look at the carburetor we see its not only a perfect machine for atomizing fuel, it also has another advantage. The joule-thompson effect.

Tests performed using quartz plates and infra red sensors located in the plenum area beneath an NHRA Pro-Stock engine revealed an intake manifold temperature drop on a 85 degree day of almost 20 degrees as a result of the the carburetor creating this effect.

So when your neighbor with EFI is ingesting 85 degree air, your power-plant could be ingesting 65 degree air.

Carbs will always make more power over EFI, but i don t know if the complexitly of the k series line would benefit from them. Maybe vtec killers would help out a bit. I guess i m the only one with crazy ideas
 

·
Registered
Joined
·
62 Posts
This is fascinating. You haven't gone very far into explaining why a "perfect" carb is such a superior inlet charge intercooler.

Perhaps the NHRA example is a bit skewed as the carbs would have been mounted well upstream of the inlet valve.

I just can't see where you got the idea that a carb is any better at lowering true inlet temp than an injector. :confused:

And who ever said the "perfect" AFR makes yo more power........... :wink:
 

·
Registered
Joined
·
285 Posts
im guessing you've read about bisi?

why EFI is superior to carbs is because carbs work better than EFI in only ideal situations; like a specific rpm band and specific throttle angle. In bisi's case, he's always full throttle and in a small rpm-band, but even then he probally has to change the jets accordingly to the weather. It also defeats the purpose of VTEC, because the low-end wouldnt be as good as the EFI system unless you tune it to work there(then it wouldnt be as good in the top end). Also, if youve noticed the VTEC systems use 2 different fuel maps for each cam profile. A carb is like just 1 fuel map that cant be modified as well as a EFI fuel map.

Another EFI system is staged injection and having the injectors outside of the intake horns on ITBs((like F1 cars); the atomization is just about as good as carbs(since the fuel spray is being ingested into the engine, almost like a carb, and not directly injected) but with better controllability(via fuel maps).
 

·
Registered
Joined
·
81 Posts
Discussion Starter #7
if you type joule thompson effect into google you can read why the intake temp is lower, but every test i have come across has the same end result. that information i posted previously was found on an old south carolina hondas thread in which MAX CFM of this board took part in and relayed his knowledge. Bisimoto has performed experiments on his own, i don t know if your familiar with his f22 setup but he runs sidedraft webers. In his testing he found that to get the same fuel atomization of his carbs the injector placement was rediculously far away and basically unattemptable
 

·
Registered
Joined
·
285 Posts
civdx94 said:
In his testing he found that to get the same fuel atomization of his carbs the injector placement was rediculously far away and basically unattemptable
I think it is possible; with staged injection(stand-off injection), and with a wide-angle fuel injectors. There was a video of a renault f1 engine being tested last year and you can see the wide-angle injectors at work and understand what im trying to get at; The injector pretty much makes a nice plume of fuel and the engine just sucks it up with the air. In the regular injection system, the injectors have a pretty narrow-angle spray(sometimes a straight spray in some port injection applications) and need "time" to expand and atomize with the air(hence placing the injectors far away).

here are some videos of a BMW with stand-off injectors that i found awhile back, pretty cool(in comparison, the F1 engine had a much finer mist than this BMW, but theyve taken the video down):
http://www.powerstation.org.uk/resources/M3_Stand_Off_Injectors_1.mpg
http://www.powerstation.org.uk/resources/M3_Stand_Off_Injectors_2.mpg
 

·
Registered
Joined
·
314 Posts
civdx94 said:
am i the only one who is thinking about putting weber sidedrafts on a k20. i m not sure if it would simplify anything or not. Just need crank trigger,ignition system, and a way to activate vtec. Vtc would be locked out of course. it obviously won t be seeing much street duty, but better atomization with higher compression along with the fact that the joule-thompson effect allows for lower intake temps which eventually leads to more power over fuel injection kinda makes it tempting. It was just a thought i wanted to share
Carbs only work as a function of restricting airflow via a venturi, so as to create a low pressure area to pull metered fuel into the airflow,(Carburation), and as such, is restricting total engine performance. The pressure drop via the venturi creates the slight air temp change, but in the overall performance picture when an engine has to work to get it's fuel (carbs) it hurts power, now when an engine has no restrictions other than to create a certain air speed for a given power band/rpm etc, (fuel injection) when properly sized and tuned is superior,better drivability,fuel distribution etc.

By the way how many new cars do you see coming out of the factories with carbs these days, not to many!
LHP www.haywardperformance.com
*Pictures and pricing for K20 underhood system now on website
 

·
Registered
Joined
·
192 Posts
technology moves forward, not backward. Sure there can be benefits to a carb style system, but if you were to take the benefits and make it modern, you will end up with some sort of fuel injector system. obviously the K series is made to perform well in a smog type envelope.

outside the box type thinking is always welcome, most of the people you bounce your ideas to however are still inside the box :p now if they were on that Ivory shit...it would be another story.

:cool:
 

·
Premium Member
Joined
·
575 Posts
Personally i think it is a great idea, and i would love to do it. There is nothing like a car you have complete control over. Ecu's are so complicated and have all these extra wires its rediculous. people leaving posts about whats a solenoid CEL? Feels like your car is controlled by a satellite or something and any little electronic pulse can cause an engine fault. Feels like house arrest or something, do something wrong, flip off a cop and BZZzzzZ. And the only way to tune is buying a chip or sometype of program that isnt really a tune, you buy a little device plug it in and presto! No any real control of whats going on inside of the brain pure electric signal, is that right pay for electric signal to make car run better? Carbs you get to sit with jetting a real hands on experience. But for now i'll just go with the flow and see what this hondata thing feels like guess i cant knock it till i try it.
 

·
Registered
Joined
·
191 Posts
i'v tried it on all my other motors, b20's, b18's, b16's, and many d series. the only advantage is that some circuts give weight advantages to carborated cars. other than that they will never out flow throttle bodies of the same size do to the venturi which is basicly a choke that increases the speed of the air for a second to in increase atomasation, they are great for atomasation because the venturi make's the air tumble down the runners insted of flowing straight. and yes tunning a vtec power curve is pretty much imposable with carbs..
 

·
Premium Member
Joined
·
575 Posts
evilxkid said:
i'v tried it on all my other motors, b20's, b18's, b16's, and many d series. the only advantage is that some circuts give weight advantages to carborated cars. other than that they will never out flow throttle bodies of the same size do to the venturi which is basicly a choke that increases the speed of the air for a second to in increase atomasation, they are great for atomasation because the venturi make's the air tumble down the runners insted of flowing straight. and yes tunning a vtec power curve is pretty much imposable with carbs..

what carbs did you use? I dont tune for max power either which is why this so called restrictive venturi does not bother. you sound like tuning vtec with a turbo is any easier, i would much rather give up the headache of wires for knowledge of fine tuning. Afterall it is cars we are talking about here isnt it?
 

·
Registered
Joined
·
191 Posts
i'v ran mikunis and webers bolth. the mikunis where nice, but the webers where easyer to find parts and jets for. ya if your not fine tuning than it's not to big of a broblom. i'm just glad i made the switch to an efi system.
 

·
Registered
Joined
·
62 Posts
So, my question is, if a carburettor is so superior, why is no one making superior HP on them?

And why has the entire high performance and motorsport world relegated the carburettor to the bottom of the cupboard? (Except for certain parts of the North American market).
 

·
Premium Member
Joined
·
575 Posts
EFIOZ said:
So, my question is, if a carburettor is so superior, why is no one making superior HP on them?

And why has the entire high performance and motorsport world relegated the carburettor to the bottom of the cupboard? (Except for certain parts of the North American market).

because they are not very compatible with turbo's and super chargers. They can be messy. i hate to say but is this not self evident?
 

·
Registered
Joined
·
62 Posts
Not really. I keep getting these people tell me how much better life would be with carbs or how you can make more HP with carbs, etc, etc.

But I have never seen anyone actually doing it..........
 

·
Registered
Joined
·
1 Posts
Super digging up the dead here and my first post no less but this is a frequent google search result and I registered just to add this re tuning carbs and vtec

Local circle track beater car running b16 motor has a custom (shadetree) intake manifold that mounts a big 4 barrel w mechanical secondaries. Primaries are jetted to nonvtec needs and carb has enough flow to feel like its floored on the primaries alone...not sure what % he has the secondaries open at but they are jetted for vtec.

Unfortunately this doesnt help if you want the wail of an IR style intake but it WOULD be an easy way to tune a carb and keep vtec crackin.

The vaccum signal w 1.6l and a 650+ cfm carb is pretty weak below 2500rpm so this isnt a street friendly method and is probably best kept to budget track cars and other honda swapped off road hoon rigs.

If yall can find smaller mechanical secondary options somewhere it might even have usable throttle response.
 

·
Registered
Joined
·
253 Posts
sorry, but tuning a FI is orders of magnitudes easer to tune than a carb. Yes, when you buy a carb developed for a special application, it might come down to a few air acres and a main jet, but good beware you have to start from scratch. idle air screws, pilot jets, needle position and needle shapes, emulsion tube diameter and type, main jets. They are horrible to tune. There is very little magic in tuning ECUs except that all can be changed in software within seconds. You can focus on the tune and not waste hours taking 4 carbs apart, change a jet and see if the part to full throttle transition become better.
If one is on the level of being confused by a CEL solenoid issue, that person is likely neither comfortable with even a KPro/Kmanager nor with properly setting up a multicarb system.
I have yet to meet a person with significant carb experience that even once looked back after working with programmable fuel injection systems. Especially on engines and cars that were designed for fuel injection. Classics is slightly different.
Even for racing, little beats automatic air temp correction, coolant temp correction, knock control, closed loop fueling, perfect cold and restart capability, wide torque band of programmable cam timing and lift, and the list goes on.

On a K-Series Honda, VTC and VTEC offer so much extra capability beyond peak power, even a racer won't reject unless class regulations require it.

Yes, fuel injector location can effect peak power, hence some efforts to do dual injection. For all roughly except power between peak torque and the limiter the injector location close to the head is most advantageous.

I don't miss a choke. And endlessly fiddling with the 4 Mikuni carbs on my RG500. Would love a FI system on it.
 
1 - 20 of 20 Posts
Top