Mike's Badass Quad Carb Manifold!! Build PICS!!!
Because it has a carb. And it's about to get worse, 'cause he's getting 4 of them
Started milling.
Someone on 3geez told me once that the A20/B20A leans forward at a 15 degree angle. Lets hope so, or else John's carbs are gonna hafta suck at an angle.
Meet the worst mill vise in the world, world, worst mill vise ever....
Gotta lay out some holes! Hope that center spacing is in fact 85mm, 90mm, 85mm!
Big holes now!
Last edited by Ichiban; 11-09-2009 at 05:15 PM.
ICHIBAN!
"Now, even more better!"
Someone on here flamed me once for suggesting drilling a 1/2" hole. Showed them...
The boring head makes an accurate, snug fit over the tubes...
Digi makes it easy...
...life is sooo boring....
They fit!
Cut to the same length. We're not building a GM here, people!
Mocked up, and tacked into place.
ICHIBAN!
"Now, even more better!"
Squishy squishy!
MORE squishy squishy!!
Not too bad of a fit...
First runner welded up...
And precisely HERE is where I ran out of fucking MIG gas.
More when the bottle is full!!!.....11!!
ICHIBAN!
"Now, even more better!"
awesome work there!! top stuff
Fuck that is sex!!!!!
Holy shit dude! That's fucking rad! Looks awesome!! Thanks so much for the work! Hope you're having fun making that shit. BTW, if anybody needs any shit done, this guy is the man!
Hey John, feel free to rename this thread so it makes sense to everyone!!
ICHIBAN!
"Now, even more better!"
WinRAR
1988 Honda Accord LX-i Coupe 123k miles.
now that is how you build a real manifold
1989 Honda Accord LX-i
B18c1 swap since 7/2011
175whp and 132tq
Redzone tuned
Amazing work
man that looks good mike john will be one happy chappy
Absolutely amazing!
what ? no JB weld?boy this brings back memories, maby i will be able to finish mine one of these days, i had to do the same thing with the plate thats tig welded on to the piece of factory manifold on mine, lets see more details of how you matched the ports where the round edge and oval piece come together. I still need to do a little bit of port matching. also how are you going to support the manifold from underneath? how are you going to add a balance tube? you really need one with that many carbs or they will do all kinds of weird things.
Last edited by lostforawhile; 11-10-2009 at 08:01 AM.
I already tapped 4 NPT bungs in the runners on the stock part of the manifold. Those will feed into a collector box of sorts, but only for MAP/vacuum purposes. I don't know if there's really any need for balance tubes for the purpose of the carburetors. Seems kinda like it would kill the whole point of the individual runners... They didn't have any sort of setup like that as they were practically bolted to the cylinder head on the motorcycle they came off of. The original "manifolds" were just little rubber grommets of sorts.
^^^ the bungs on each tube and routed to a common "box" should do the trick.
factors to consider:
*vacuum drop at off idle throttle to wot and carb setup matching to engine load
*cam profile and head flow charactoristics in regards to getting the vacuum required to pull from idle circuits of carbs x4 zomg
*vacuum draws sa pvc-brake booster etc you do not have on a scooter
Also To give an example of how variances of can affect our carb set ups: I put a progressive style weber 32/36 on my dx that has the cygnusx1 "spread bore" intake (oem with plenum divider cut out completley to accomdate a weber 38 full time 2 bbl carb) and it runs just like doggy doo. The same carb ran beautifully on the stock oem intake. I understand why, but it is amazing to see how much different the carb behaves. There is plenty of go power once the engine opens up but low end is nothing nadda.
Believe it or not, that is actually aluminum MIG.Originally Posted by lostforawhile
There's not really much to show right now, I crimped the tubes in the vise to the same height as the ports, however they are slightly lacking in width. As you can see, the carb spacing is slightly narrower than the port spacing, causing the two outer ports to be offset slightly to the inside. The two center ports are as well, but not as much. In fact, the outer ports came flush to the inside edge of the tubes, where the inner ports are more centered over their tubes. I plan on adding material to the inside of each port where it is shy, the outside of the tube, and splitting the difference in a gradual blend.
Surprisingly, reusing the factory manifold flange actually helped somewhat as the short leftover lengths of runners already begin that inward curve.
I didn't really have any plans yet for an underbrace. As it is, the intake only weighs like.0003 pounds, and most of that is the flange. Balance tube? I suppose I'll leave that up to the customer!
ICHIBAN!
"Now, even more better!"
That shouldn't be a problem since the carbs I have a CV carbs. I believe that is the other way to prevent the vacuum drop off since the carbs don't have accelerator pumps.
I haven't read everything on B20A cams yet, but I've been reading a lot on PreludePower and the 3g B20A, since they've got mostly the same internals and share cams. But yeah, that will definitely be something to consider. Maybe a 1500RPM idle?*cam profile and head flow charactoristics in regards to getting the vacuum required to pull from idle circuits of carbs x4 zomg
I was reading about Cygnus' setup with his ITBs and from what I can remember, he ran his booster to just one runner, and there was more than enough vacuum to run his booster. But I could be thinking of someone else. Lots of DCOE manifolds I've seen are set up this way too, with one bung on only one runner. I guess I'll find out myself soon.*vacuum draws sa pvc-brake booster etc you do not have on a scooter
I see what you're saying. I wondered how much that would change the way the car runs and drives. On my 1gee, I'm running a 32/36 and I cut out the divider as much as I could. It's not completely gone, but mostly. I've still got a ton of off idle throttle response with that motor. Could be the cam though, since the power pretty much dies off at 5500RPM really hard. I wonder if a stock plenum with some dividers built up and matched all the way up to the carb would help my top end at all...Also To give an example of how variances of can affect our carb set ups: I put a progressive style weber 32/36 on my dx that has the cygnusx1 "spread bore" intake (oem with plenum divider cut out completley to accomdate a weber 38 full time 2 bbl carb) and it runs just like doggy doo. The same carb ran beautifully on the stock oem intake. I understand why, but it is amazing to see how much different the carb behaves. There is plenty of go power once the engine opens up but low end is nothing nadda.
Seems that the shop is being gay about not getting more argon for Al MIG until there's a panic rush job need for it. In which case they won't have it
So hopefully someone comes in soon for aluminum, because the shop refuses to refill the bottle just for John's manifold.
ICHIBAN!
"Now, even more better!"
Don't they realize the importance and impact on humanity this manifold will have?
thats some sexy work
200+ ALL MOTOR LS VTEC
I think they're pissed off at me for my miserable attitude at work all week
ICHIBAN!
"Now, even more better!"
i agree. this thing is awesome! makes me want to make my manifold agian.
thanks mkymonkey
Bitchin man, a quad carb setup! Looking good so far. Makes me wish I had aluminum welding capability. Having just gone through a failed ITB build (failed for the time being anyway) I can say welding up the runners is the way to go. I tried using silicone couplers, which did work but they have very little mechanical strength, and need bracing to make sure they don't come apart.
A balance tube shouldn't be absolutely necessary as long as the carbs have some means for adjusting the throttle blades relative to each other. What kind of carbs are going on here anyway?
For the brake booster and other vacuum stuff it would be better to tap from all of the runners equally to spread the draw out. I tried running the booster from a single runner and it did work but I wouldn't do it permanently.
What engine is this going on? Any other mods on it?
C|
Apparently the carbs will be Mikuni BST 38SS carbs. The engine is a (first gen) JDM B20A gold top. Ask 2ndgenguy about mods, I'm sure there will be several.
I'm still trying to dream up a better vacuum manifold setup, but haven't really figured anything out for sure. As I remember, the ET2 twin carb setup runs the brake booster off of one or two ports only anyways. That system also has enough additional vacuum lines to build a large slingshot with
How'd the ITB's fail? Maybe I could somehow help, provided the shop hasn't permanently vetoed Al Mig gas for the foreseeable future.
ICHIBAN!
"Now, even more better!"
They're 38mm carbs from a GSXR750. I wasn't sure if they were going to be big enough to run a 160hp motor. But I calculated the airflow compared to a single stock throttle body and there does seem to be about 50% more throttle area with these. But that's all I really have to go on, some trial and error.
I'm not 100% sure on what mods yet. I don't think I'm going to do anything super wild yet. Compression bump, some cams, get some bottom end lightening done... Not sure yet if I want to do headwork or not. Definitely will have to have a custom header built for it. Hope to get maybe 180bhp out of it. Hopefully the carbs can keep up. Hopefully I can figure out how to jet them, and change the needles and all that. I'm hoping that the fact that they're CV carbs will let them be forgiving. The car ran and idled with the stock jetting on the carbs, so it can't take too much. Here's a video I did before I had Mike make me his badass manifold, and before I found out the engine was fucked:
http://www.youtube.com/watch?v=pPs92KrCaj8
I hardly think your ITB project was a failure. It's probably pretty frustrating for you at this point, but there's still some interesting potential there. Did you ever get videos of how your car was running, or maybe some pics of that manifold all assembled and installed on the car with the throttle bodies?
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