intake manifold ideas. the quest for more power.
03-29-05, 08:55 AM
#1
intake manifold ideas. the quest for more power.
well, i have been wanted to modify my intake for the longest. doing reaserch on and off of rx7club and my native sight homemadeturbo.com ( you guys wanting to convert your na to turbo, this is a good websight as they are very knowledgable. also, lets just say they are not as proper with their doings, but they get the point across) led me to also everyone enlarging the ports for the intake manifold. at first cfm is good blah blah blah was the only thing i was hearing. eventually i stumbled apon some documentation on here and some information here http://mototuneusa.com/think_fast_intake_porting.htm
after reading this, i immediatly began figuring ways to improve intake for my 86 gxl. how could i effectively get more power out of my intake manifold.
the first thing to do, is remove restrictions.
the 5th and 6th ports are going out. also, those fuel injector pedistals look like a restriction, so out they go. dont lecture me on how they affect fuel distrobution unless youve taken them out and have actually done a study. point being, they are restrictive and out they go. next point of interest is the 5th and 6th ports. some people wire them open, but why would you wonna do that when it does nothing. lemme say that again. it does nothing. so Ddub gave me the idea to remove the actuators and the rods. at first it seemed like a great idea, but after carful consideration, it wasnt a good idea to just remove the rod and leave the sleevs in there as they could viberate in there and turn and whatnot. so, i just fugured nothing can be done here except bu yanking them out.
so whats the deal with the cfm thing? well, going to the websight i posted (http://mototuneusa.com/think_fast_intake_porting.htm) cfm does NOTHING for intake porting. what matters is velocity. having a smaller intake runner will increas velocity. but when i apply this to the rx7 intake, it seems like it is far too long. the intake runners are atleast 3 and a half inches in lench straightened out (guestimate). maybee not that much, but its cetainly seems likely. so what can i do to increas intake velosity?
shorten the runners. GREAT!!. my lame brain crackpot idea was to cut the uim in half and cut either a nice 1 inch piece of intake runner out, or to either take that to the next level and then take off the most metal i can in effort to reduce runner length.
no thats all great and dandy, but i hit a road block. ive seen those nifty intakes that are hand made and all that bull honkie, but i was thinking of using the stock intake manifold. the more you cut out the more the intake manifold moves closer to the right side fender and wheel well. this isnt good. not one bit.
now my question is, whats yalls input on this situation. anything positive would help out allot.
after reading this, i immediatly began figuring ways to improve intake for my 86 gxl. how could i effectively get more power out of my intake manifold.
the first thing to do, is remove restrictions.
the 5th and 6th ports are going out. also, those fuel injector pedistals look like a restriction, so out they go. dont lecture me on how they affect fuel distrobution unless youve taken them out and have actually done a study. point being, they are restrictive and out they go. next point of interest is the 5th and 6th ports. some people wire them open, but why would you wonna do that when it does nothing. lemme say that again. it does nothing. so Ddub gave me the idea to remove the actuators and the rods. at first it seemed like a great idea, but after carful consideration, it wasnt a good idea to just remove the rod and leave the sleevs in there as they could viberate in there and turn and whatnot. so, i just fugured nothing can be done here except bu yanking them out.
so whats the deal with the cfm thing? well, going to the websight i posted (http://mototuneusa.com/think_fast_intake_porting.htm) cfm does NOTHING for intake porting. what matters is velocity. having a smaller intake runner will increas velocity. but when i apply this to the rx7 intake, it seems like it is far too long. the intake runners are atleast 3 and a half inches in lench straightened out (guestimate). maybee not that much, but its cetainly seems likely. so what can i do to increas intake velosity?
shorten the runners. GREAT!!. my lame brain crackpot idea was to cut the uim in half and cut either a nice 1 inch piece of intake runner out, or to either take that to the next level and then take off the most metal i can in effort to reduce runner length.
no thats all great and dandy, but i hit a road block. ive seen those nifty intakes that are hand made and all that bull honkie, but i was thinking of using the stock intake manifold. the more you cut out the more the intake manifold moves closer to the right side fender and wheel well. this isnt good. not one bit.
now my question is, whats yalls input on this situation. anything positive would help out allot.
03-29-05, 09:47 AM
#2
Former Moderator. RIP Icemark.
Have you already ported the engine; that you are looking at changing the intake???
And whats the point of removing the aux ports??? You want to loose low end power just to make a little more top end?
If you really want to smooth out the obstructions in the intake you need to have it extrude honed as I have done.
And whats the point of removing the aux ports??? You want to loose low end power just to make a little more top end?
If you really want to smooth out the obstructions in the intake you need to have it extrude honed as I have done.
03-29-05, 11:05 AM
#3
there arent really any obstructions from what i see. the only rational thing that can be done is shortening the length of it. also, you shouldnt care about what i want for low end. thats my own decision.
i want to do it because its never really been explored too much. whys that? i dont know.
i want to do it because its never really been explored too much. whys that? i dont know.
03-29-05, 12:29 PM
#4
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Originally Posted by Icemark
If you really want to smooth out the obstructions in the intake you need to have it extrude honed as I have done.
(Sorry to hijack)
03-29-05, 12:45 PM
#5
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By hacking off part of the manifold you have changed the pressure wave frequencey pushing it up, giving you less "ram effect" in the lower and mid range rpms, and possibly pushing it up high enough that it won't even be in your powerband anymore. You have also lost the increase in V.E. that the ram effect gives as well. Velocity isn't the only thing to worry about, you can have high velocity with half inch runners but it will starve the engine for power. If you want to hack around and possibly destroy your intake go ahead. If you want LOGICALLY create an intake to increase horsepower, than start researching, get all the equations do the calculations and then either make one, or have someone else make it to your needed specifications.
- Steiner
- Steiner
03-29-05, 04:42 PM
#6
nah i wasnt going to hack mine up. i was going to get one off of someone thats willing to do it, but i came to a starteling conclusion. the tb will be too close to the damn wheel well.
i also have a crackpot idea of putting a suzuki gsxr indevidial throttle setup on the lower intake manifold. you know, just make a flange, and stick on the lim. and configure everything so that i can run the stock ecu, but tune it via an safc2.
i also have a crackpot idea of putting a suzuki gsxr indevidial throttle setup on the lower intake manifold. you know, just make a flange, and stick on the lim. and configure everything so that i can run the stock ecu, but tune it via an safc2.
03-29-05, 06:01 PM
#7
First off I am going to mention the importance of flowtesting. Don't confuse this to think that everything should flow the most that it possibly can. You need to balance all of this out with velocity. The key is to have the most flow that you can while still having the smallest opening that you can. Too many people wrongly think that it should just flow more since more is better. More is only better if more is needed. If you have a flowbench, you can find the most flow possible but from the smallest space possible. This doesn't mean that smaller is always better nor does it mean that larger is always better. It is a balancing act. Only go as large as you need. Any larger is not necessary. In the link you posted where the guys talks about the flaws in flowtesting, he is making the same mistake many others make with them too. He is assuming that you just want to port until everything is maxed out. If you know how to use one properly, you'll know how to maximize what you have for what you need without going crazy just looking for the last little number. I do agree that many smaller ports are faster. Obviously they don't look as good on a bench. Experienced people don't make this mistake with a flowbench. Inexperienced people do. It's all about knowing how to use your tools properly. Nevertheless it is a very good article.
The biggest thing that has not been mentioned and I hope not overlooked is the stock ecu and air flow meter. The stock afm has 5 sq. in. of area when fully opened. This is not much room for air to flow through and is less area than any other area in your induction system. This isn't even accounting for the spring loaded flapper door that is obstructing flow like no ones business. Your afm flows about what a single 2" pipe can flow on it's own. Everyone and their dog overlooks this and foolishly tries to tune their cars with those archaic bandaids called S-AFC's. If you insist on going slow, go this route. If you want to go faster, dump the stock ecu and it's afm and get a standalone. You'll pick up 20 hp just by removing the afm and this doesn't even account for properly tuning te unit in. People say standalones are too expensive. Consider that most people go crazy trying to get that last little fraction of a horsepower out of their car but when it comes to real gains they won't pay for them. Very flawed logic. There is no point in freeing up breathing in some spots when there is still a very serious restriction before it all. I really hate the saying "every little bit counts". While this is indeed true, it only counts if it is in a place where it can actually do some good. Making an opening larger than it is is worthless if it was larger than the smallest spot to begin with. This would equal a decrease in velocity at this spot and would hurt power.
Removing the injector locations will hurt power. It sounds strange but you really need to see it in a flowbench to understand. The stock manifold can only have it's flow increased by about 10% over stock. This does not equate to 10% more power nor does it imply even 10 more horsepower. As long as the stock afm is in the way, this added flow is doing nothing. There is also no point in trying to retune the intake for a higher rpm. By almost 5000 rpm, your afm is already fully open. It is a big restriction after this point. There's no point in trying to get more power up high because of this. You'll basically end up losing low end and not gaining any noticable top end. You are now slower than stock! Go read Paul Yaw's tech articles. The one about flowtesting is very enlightening and he does mention the most common mistakes made by people modding their intake manifolds on these cars. Your idea is making these mistakes.
Too many people here do not know how to mod their cars properly. There are a few that do. Take a look at Kahren's car. He only has an intake manifold that he built and a Haltech. That's it. No exhaust, nothing. He put down more power with a flatter curve than most people here do with ported engines and full mods. I guarantee that he spent less money to do it and that his car is more streetable than most others. This is the way to do it. Instead of spending the money and time on trying to acquire and build something that isn't going to do anything useful, save that money, sell that S-AFC bandaid, and put the money towards any form of standalone. They really don't cost much, they aren't hard to tune at all, you don't need a dyno to tune them, and you'll be faster than your idea. Once you do this, then you can go back later and try other things. Now there will be no restrictions to worry about and you can tune it properly. You'll be glad you went this route. I did and I feel dumb for wasting all the effort trying to mod things. Been there done that. Don't make the same mistake.
The biggest thing that has not been mentioned and I hope not overlooked is the stock ecu and air flow meter. The stock afm has 5 sq. in. of area when fully opened. This is not much room for air to flow through and is less area than any other area in your induction system. This isn't even accounting for the spring loaded flapper door that is obstructing flow like no ones business. Your afm flows about what a single 2" pipe can flow on it's own. Everyone and their dog overlooks this and foolishly tries to tune their cars with those archaic bandaids called S-AFC's. If you insist on going slow, go this route. If you want to go faster, dump the stock ecu and it's afm and get a standalone. You'll pick up 20 hp just by removing the afm and this doesn't even account for properly tuning te unit in. People say standalones are too expensive. Consider that most people go crazy trying to get that last little fraction of a horsepower out of their car but when it comes to real gains they won't pay for them. Very flawed logic. There is no point in freeing up breathing in some spots when there is still a very serious restriction before it all. I really hate the saying "every little bit counts". While this is indeed true, it only counts if it is in a place where it can actually do some good. Making an opening larger than it is is worthless if it was larger than the smallest spot to begin with. This would equal a decrease in velocity at this spot and would hurt power.
Removing the injector locations will hurt power. It sounds strange but you really need to see it in a flowbench to understand. The stock manifold can only have it's flow increased by about 10% over stock. This does not equate to 10% more power nor does it imply even 10 more horsepower. As long as the stock afm is in the way, this added flow is doing nothing. There is also no point in trying to retune the intake for a higher rpm. By almost 5000 rpm, your afm is already fully open. It is a big restriction after this point. There's no point in trying to get more power up high because of this. You'll basically end up losing low end and not gaining any noticable top end. You are now slower than stock! Go read Paul Yaw's tech articles. The one about flowtesting is very enlightening and he does mention the most common mistakes made by people modding their intake manifolds on these cars. Your idea is making these mistakes.
Too many people here do not know how to mod their cars properly. There are a few that do. Take a look at Kahren's car. He only has an intake manifold that he built and a Haltech. That's it. No exhaust, nothing. He put down more power with a flatter curve than most people here do with ported engines and full mods. I guarantee that he spent less money to do it and that his car is more streetable than most others. This is the way to do it. Instead of spending the money and time on trying to acquire and build something that isn't going to do anything useful, save that money, sell that S-AFC bandaid, and put the money towards any form of standalone. They really don't cost much, they aren't hard to tune at all, you don't need a dyno to tune them, and you'll be faster than your idea. Once you do this, then you can go back later and try other things. Now there will be no restrictions to worry about and you can tune it properly. You'll be glad you went this route. I did and I feel dumb for wasting all the effort trying to mod things. Been there done that. Don't make the same mistake.
Last edited by rotarygod; 03-29-05 at 06:22 PM.
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03-29-05, 06:42 PM
#8
Former Moderator. RIP Icemark.
after reading the articles you posted, The association that you are attemtping with a Rotary engine falls flat.
#1 the HP listed on his dyno chart for the Yamaha R6, actually shows the stock larger port producesmore HP at the peak range for a rotary engine (5000-7000 RPM). His only major gains are at 8000 RPm and above (but are only typically 5 HP) well above the normal operating range of a rotary engine in an automotive street application.
#2 his method falls down in the face of Miller cycle and post 83 rotary technology where intake ports are delibertly left open to force part of the intake charge, back into the next opening port or valve and intake cycle.
See the intake on a miller cycle and rotary engine are by-directional, his "scientific method" only considers the intake tract to be a one way device.
#3 He claims that his method is based on the intake is still marginally open at 55 degrees... well in a turbo rotary engine the intake ports are completely closed at 50 degrees(ATDC), while a non turbo at under 3800 RPM is completely closed at 40 degrees (and 70 degrees above 3800 RPM on a non turbo where the Dynamic Intake Efffect is happening and the aux ports are open, but then he doesn't have DEI on a BIKE engine).
#1 the HP listed on his dyno chart for the Yamaha R6, actually shows the stock larger port producesmore HP at the peak range for a rotary engine (5000-7000 RPM). His only major gains are at 8000 RPm and above (but are only typically 5 HP) well above the normal operating range of a rotary engine in an automotive street application.
#2 his method falls down in the face of Miller cycle and post 83 rotary technology where intake ports are delibertly left open to force part of the intake charge, back into the next opening port or valve and intake cycle.
See the intake on a miller cycle and rotary engine are by-directional, his "scientific method" only considers the intake tract to be a one way device.
#3 He claims that his method is based on the intake is still marginally open at 55 degrees... well in a turbo rotary engine the intake ports are completely closed at 50 degrees(ATDC), while a non turbo at under 3800 RPM is completely closed at 40 degrees (and 70 degrees above 3800 RPM on a non turbo where the Dynamic Intake Efffect is happening and the aux ports are open, but then he doesn't have DEI on a BIKE engine).
03-29-05, 07:06 PM
#9
Originally Posted by rotarygod
The biggest thing that has not been mentioned and I hope not overlooked is the stock ecu and air flow meter. The stock afm has 5 sq. in. of area when fully opened. This is not much room for air to flow through and is less area than any other area in your induction system. This isn't even accounting for the spring loaded flapper door that is obstructing flow like no ones business. Your afm flows about what a single 2" pipe can flow on it's own. Everyone and their dog overlooks this and foolishly tries to tune their cars with those archaic bandaids called S-AFC's. If you insist on going slow, go this route. If you want to go faster, dump the stock ecu and it's afm and get a standalone. You'll pick up 20 hp just by removing the afm and this doesn't even account for properly tuning te unit in. People say standalones are too expensive. Consider that most people go crazy trying to get that last little fraction of a horsepower out of their car but when it comes to real gains they won't pay for them. Very flawed logic. There is no point in freeing up breathing in some spots when there is still a very serious restriction before it all. I really hate the saying "every little bit counts". While this is indeed true, it only counts if it is in a place where it can actually do some good. Making an opening larger than it is is worthless if it was larger than the smallest spot to begin with. This would equal a decrease in velocity at this spot and would hurt power.
03-29-05, 11:00 PM
#10
My engine is an '84 streetported (not large) 6 port with an S5 n/a intake manifold running Megasquirt. When you get yours built let me know and I'll help you with a base map. It all sounds scary but you learn everything so fast as you build these. People are currently working on the leading/trailing timing split control right now and the ultimate goal is to make it a plug and play system for the 2nd gen. It's only going to get easier. If you buy a wideband O2 sensor and controller which is a few hundre dollars, you an actually program the Megasquirt maps based on desired a/f ratio. Just a little code update. That is as simple as it gets.
Do not get rid of the stock ecu until you have the new one in a figured out. I completely pulled mine out including all the wiring but I also have another car I use as a daily driver.
Do not get rid of the stock ecu until you have the new one in a figured out. I completely pulled mine out including all the wiring but I also have another car I use as a daily driver.
03-30-05, 07:55 AM
#11
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If you feel you must have a shorter intake path try something like below. Incorporate some velocity stacks in the design and your ready to tune. Changing the length of the runners would be easy enough with a plate between the LIM and the custom intake.
http://www.sdsefi.com/techinta.htm
http://www.sdsefi.com/techinta.htm
04-03-05, 12:54 AM
#12
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http://cgi.ebay.com/ebaymotors/ws/eB...964612399&rd=1
would this be worth looking at (i know its expensive but i mean to fab it up yourself) as far as cusom intake manifolds?
would this be worth looking at (i know its expensive but i mean to fab it up yourself) as far as cusom intake manifolds?
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