PDA

View Full Version : 89 SE-i 2 Stage Intake "WHAT IF?"



turfnnsurf
03-01-2003, 08:24 AM
My question is... I have read in a few posts about guys looking into using B series intake manifolds, however IM not clear on why? Is it for better TQ at low RPM's or more HP at high RPM's???
The reason I ask this is because while I was preparing my extra A20 intake for porting and polishing I starting taking a closer look!!! Since this manifold has a set of butterflies controlled by vacuum (http://www.ofoto.com/PhotoView.jsp?UV=571609061485_21673085205&collid=31164085205&photoid=21164085205) What would be the benefit or loss if this stage was completely removed to allow a more direct and shorter AIR FLOW into the HEAD???? see here~~>http://www.ofoto.com/PhotoView.jsp?UV=571609061485_21673085205&collid=31164085205&photoid=61164085205

THANKS FOR ANY HELP... Brad

BoredRec
03-01-2003, 10:03 AM
Ok, I may be talking out my ass here, someone will surely tell me I'm either entirely wrong or just sorta wrong, but my understandind is that those butterfly valves are there for a reason. I think they are usually almost closed at idle, and open all the the way at WOT. The reason being is that they work on a venturi principle. When at idle the valves are almost close, which actually speeds up air. You ever been in a cave? Ever come to a place where the diameter of the cave gets smaller and smaller, until the cave is blocked off, but then starts to get bigger again? Notice how the wind picks up speed right there? Same principle. That way you'll have the power you need to accelerate. The valves are all the way open at WOT (or damn near) cuz now they don't want a lot of restriction with the airflow cuz you need it. I HOPE someone can tell me I was at least partially correct in this.

turfnnsurf
03-01-2003, 12:55 PM
BoredRec,

I understand what you're talking about with the Venturi Principle and air flow... However, my though is this with the exception of a short trip to the 7-11 or grocery store, 90% of my driving is to get on the highway and I have to stay with traffic at 75 to 80 mph. So you can understand that even merging into this traffic is a call for WOT!!!! I just went out and confirmed the operation of the butterflies at idle... THEY STAY OPEN at idle, they are spring loaded to stay open till vacuum closes them. Funny thing is the load of the spring seems high for such a small vacuum hose. I also manually closed the butterflies with the engine warm. At idle and there was no noticable affect, at least no rpm change or change in the sound of the motor running. Im just wondering if our dual stage intakes really effect the performance of the car that much??

AccordEpicenter
03-02-2003, 10:20 PM
ok heres the story, at idle or any engine speed below 5000 rpm, the bypass butterflys are closed for peak torque, and then switched open at anything above 5k for better high rpm performance. I think for all out performance youd gain some by removing this stage (thats what im trying as soon as I get another intake) and going with that. It just takes out some low end torque. By locking my bypass open all the time, i lost some low end torque but it pulls much harder after 4k rpms.

turfnnsurf
03-03-2003, 06:38 AM
AccordEpicenter,

I hate to correct you but as my post above mentions the butterflies stay OPEN at idle... I confirmed this with the car running and at normal temp.. They are spring loaded to stay open till sufficient vacuum closes them i would assume at speed(higher RPM's)

88LXi/87CRXSi
03-03-2003, 02:26 PM
I have to agree with AccordEpicenter. From the service manual:

Satisfatory power performance is achieved by closing and opening the bypass valves. High torque at low RPM is achieved when the valves are closed, whereas high power at high RPM is achieved when the valves are opened.
There should be manifold vacuum at line 13, bypass hose, at idle holding the valves closed or you have a problem in your controls!

-Steve

turfnnsurf
03-03-2003, 02:32 PM
Steve,

Well then maybe i have a vacumm problem, cause my bypass valves are open at idle, when the engine is at normal operating temp... i'll goto the napa near me tomorrow and pick up a vacuum tester to check but can someone post what vacuum values i should be looking for??

88LXi/87CRXSi
03-03-2003, 02:48 PM
lets see probably the best way to figure out which valve to check is to post a link to the mystery box!

88 EFI Vacuum control box (http://members.nccw.net/heywood/88LX-i%20control%20box.jpg)

You're gonna look for the bypass control soleniod valve. I might be wrong on this, but I think ther should be 12v at to solenoid coil too, and 0v when you raise the RPM above 5000.... I think:huh:

-Steve

*edit- as far as how much vacuum you should have, don't really know , but hows 18-24 " Hg sound?????

turfnnsurf
03-03-2003, 08:07 PM
Steve, I'll take a look at it all tomorrow after i goto Napa and pick up a vacuum tester of some sort. i'll post my findings later on.. thanks for the help

joker2
04-01-2003, 07:54 AM
I think for people who are running b16 manifolds, they should be able to do away with this vacumm line all together because those manifolds don't have butterfly gates........:D

skaterjunky8
04-03-2003, 01:46 PM
If you are putting on a B16 manifold do you NEED to port the head to match up with the manifold or are you safe with just bolting it on?

AccordEpicenter
04-03-2003, 01:56 PM
it would probably physically work, but run like crap, so if you were gonna invest the time into working on this id portmatch, at the least

joker2
04-04-2003, 05:31 AM
Trust me when I say there's no just putting it on....... I've been working on my mani. on and off now and there's some work that goes into making this work..... But I would recommend that you port match as well......:D

TWOLOUDNPROUD
06-02-2003, 11:48 PM
MY butterflies did not work and i fix it it was the Vacum control in the black box was bad for it i put a new one a now it works great the Vacum hoes 12 and 13hook to it. It makes a big difference if you need to know more E mail me.

POS carb
07-04-2003, 12:05 PM
Originally posted by turfnnsurf
My question is... I have read in a few posts about guys looking into using B series intake manifolds, however IM not clear on why? Is it for better TQ at low RPM's or more HP at high RPM's???
The reason I ask this is because while I was preparing my extra A20 intake for porting and polishing I starting taking a closer look!!! Since this manifold has a set of butterflies controlled by vacuum (http://www.ofoto.com/PhotoView.jsp?UV=571609061485_21673085205&collid=31164085205&photoid=21164085205) What would be the benefit or loss if this stage was completely removed to allow a more direct and shorter AIR FLOW into the HEAD???? see here~~>http://www.ofoto.com/PhotoView.jsp?UV=571609061485_21673085205&collid=31164085205&photoid=61164085205

THANKS FOR ANY HELP... Brad

I have that setup in my garage, it is much better that way