OBX intake manifold

[Slippi84]

Ok first things first people that hate this product and have never used it just leave now as you will save us from a argument and keep this open so useful information can actually get passed around. We all already know the flaws of this obx manifold. Now there are somethings that can't be helped like the quality of the metal and what not but as for drilling and porting and what not I took a couple pictures I'm trying to get people to use paint and indicate which area's of the obx manifold need to be fixed or made better to make it a better manifold maybe not great but atleast better. ANyway here it goes.

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[bostonhatcher]

After you get it installed let me know if you feel any difference. I have a friend who has every bolt-on on his '98 Talon Esi but the intake manifold.

 

[Slippi84]

After you get it installed let me know if you feel any difference. I have a friend who has every bolt-on on his '98 Talon Esi but the intake manifold.

Will do. I know that what i'm doing isn't practical because of how much money it will cost to first buy this manifold then for the porting and shaving and custimizing I want done but still I just want to show that with some modification this manifold can do the job. So far I'm opening up the tb whole to accomidate a jeep tb porting out the runners to make them flush and of course retapping any wholes that need to be bigger and making a mouting spot for the map sensor.

 

[Slippi84]

this is my biggest problem with it is that there is a lip on the inside of the runners that air wouuld hit.

 

[Slippi84]

That should be about how it will look after jeep tb install. That's not to size but it's an idea of how I want to enlongate the whole make it more toward teh center of the plenum face too. My idea was to mount to tb take the flapper off and mark the circumfrance of the tb and how it sits take it off then cut.

 

[Blitzeclips]

If I had bought that manifold for $20, here's what I'd do to it *before I installed it*..

1) Spot/stitch weld around the ports and upper plenum to increase the original strength of the manifold.
2) Tap into it ONCE. Use that one avaialable vacuum source for a vacuum box. That way there's always a dedicated vacuum source and you don't drill a dozen holes into the manifold. Makes it more likely to leak...
3) Port and knife edge the injector humps/ runners. More velocity going into the combustion chamber equals better/stronger spark.
4) Of course tap it for all sensors.
5) Buy a composite plenum spacer from Paul to preent heat exchange from the head onto the lower plenum..

Honeslty, if I did all the things listed above I would feel pretty comfortable using an OBX manifold...

 

[Slippi84]

If I had bought that manifold for $20, here's what I'd do to it *before I installed it*..

1) Spot/stitch weld around the ports and upper plenum to increase the original strength of the manifold.
2) Tap into it ONCE. Use that one avaialable vacuum source for a vacuum box. That way there's always a dedicated vacuum source and you don't drill a dozen holes into the manifold. Makes it more likely to leak...
3) Port and knife edge the injector humps/ runners. More velocity going into the combustion chamber equals better/stronger spark.
4) Of course tap it for all sensors.
5) Buy a composite plenum spacer from Paul to preent heat exchange from the head onto the lower plenum..

Honeslty, if I did all the things listed above I would feel pretty comfortable using an OBX manifold...

Sounds good but the vaccume box setup the manifold isn't there already a whole for vaccume port so why would I need to tap another whole?

edit: and can you show me the injector hump runners yoru talking about I keep hearing people talk about this but not exactly where they're talking about.

 

[VelocitàPaola]

3) Port and knife edge the injector humps/ runners. More velocity going into the combustion chamber equals better/stronger spark.

Air intake velocity has little to do with spark strength. It's all about fuel mixing, and flow efficiency.

5) Buy a composite plenum spacer from Paul to preent heat exchange from the head onto the lower plenum..

Spacers are for two piece designs only... they wouldn't work with a one piece OBX.

 

[Blitzeclips]

Air intake velocity has little to do with spark strength. It's all about fuel mixing, and flow efficiency.



Spacers are for two piece designs only... they wouldn't work with a one piece OBX.

I don't know, I meen velocity for the most part is flow. The stronger the flow the stronger the mix. The stronger the mix the stronger the spark. Not to mention it allows more air into the combustion chamber too..

You couldn't use just one of the two pieces? I can't see whynot. Atleast between the head and lower plenum flange..

Check your inbox BTW.. .

 

[Slippi84]

The spacer idea isn't gonna work cause from what I hear the jeep tb on a obx is already hard to fit w/o hitting the firewall.

 

[VelocitàPaola]

I don't know, I meen velocity for the most part is flow. The stronger the flow the stronger the mix. The stronger the mix the stronger the spark. Not to mention it allows more air into the combustion chamber too..

You couldn't use just one of the two pieces? I can't see whynot. Atleast between the head and lower plenum flange..

Check your inbox BTW.. .

My inbox is empty...

Anyway, the spacer fits between the upper and lower halves of the intake manifold -- not between the head and the manifold. The two flanges are different, so you can't just put the spacer elsewhere. Furthermore, if you were to use a thick spacer like mine between the head and intake manifold, you start screwing with things like injector spray dynamics, and bracketry needs to be more severely altered.

The "stronger the mix" still has nothing to do with spark. While it's true that real high combustion chamber pressures can wash out a weaker spark, nothing about the incoming air/fuel mix will create a stronger spark... that's all the coil and wires.

And velocity is not flow, whatsoever. They share an abstract relationship, but the terms are not interchangeable in any sense. In most cases, in fact, one is sacrificed for the other. High velocity (i.e. narrowing runners), yields less flow, while high flow (wide runners), yields less velocity.

 

[Slippi84]

Does anyone know if there are any mounting issues with the jeeb tb cause i'm looking at the jeep tb's on ebay and they don't look as simple as teh mounting locations on the obx?

 

[BigRand]

Umm its been a while since I've seen it around, but there should be a tech guide, either on here or on 2gnt.com regarding The Jeep TB mod, its not just a simple bolt on, you have to take certain parts from it and mate it with parts from the stock TB to get what we call a frakenstine Jeep TB

I personally forget exactly how big the Jeep TB is, but if you didn't want to deal with the hassle, you could order a 60mm TB from modernperformance or howell, Or you could be like DSM_Zero and have a 90mm TB welded up to the intakemanifold.

 

[Slippi84]

Umm its been a while since I've seen it around, but there should be a tech guide, either on here or on 2gnt.com regarding The Jeep TB mod, its not just a simple bolt on, you have to take certain parts from it and mate it with parts from the stock TB to get what we call a frakenstine Jeep TB

I personally forget exactly how big the Jeep TB is, but if you didn't want to deal with the hassle, you could order a 60mm TB from modernperformance or howell, Or you could be like DSM_Zero and have a 90mm TB welded up to the intakemanifold.

I thought about that but that shit has to be real bad on low end power. the jeep tb is 60mm that funnels to like 57 or something like that. I read teh tech guide but see that's all facts about mounting it to a stock manifold not a obx. I would love to get a hook up like dsm-zero but seems way overkill.

 

[VelocitàPaola]

The stock TB should bolt to the OBX IM just the same... I don't see how they'd be different. Just modify the Jeep TB according to Metal_Jim's write-up and slap it on the OBX.

Also, some Jeeb TBs came 60mm all the way through, and others taper to 57mm.

 

[BigRand]

Is it possible to retap that manifold to fit the jeep one on their without modifying it?

Also the 60mm will be overkill until you slap a turbo on there.

Your gonna start asking questions like why do the honda guys with NA cars run like 70-75mm TB's and we get stuck with 60mm as an aftermarket upgrade for turbos...........either way I'll leave it up to the people doing the R&D and the people that have tried different things to answer those questions. I"m good with my 60mm TB

 

[VelocitàPaola]

Is it possible to retap that manifold to fit the jeep one on their without modifying it?

I doubt the material is thick enough to hold enough thread, but then again, I've never had one in my hands, so I can't say definitively.

 

[Slippi84]

Is it possible to retap that manifold to fit the jeep one on their without modifying it?

Also the 60mm will be overkill until you slap a turbo on there.

Your gonna start asking questions like why do the honda guys with NA cars run like 70-75mm TB's and we get stuck with 60mm as an aftermarket upgrade for turbos...........either way I'll leave it up to the people doing the R&D and the people that have tried different things to answer those questions. I"m good with my 60mm TB

No there is no point comparing diffrent platforms when talking about individual parts. Especialy hondas. As much rice as there is out there hate to break it to everyone but those cars were designed better then some of our cars. My pride and testosterone will not alow me to buy one but you have to give credit where credit is due.

The problem with just retapping for a jeep tb the whole they have for the stock tb isn't centered as you can see so unless you enlongate it down and to the right you will have some of the old whole location out which def isn't gonna fly. I mean if the jeep can bolt right up to where the stock goes on a stock mani and the obx was made to accomidate a stock tb i don't see why it wouldn't work.

 

[all_motor_mike]

ok here we go................ make sure the runners match the gasket along with the flange bolt holes, port atleast the first 3 "inches of the runeners to get rid of that transitoin from runner to flange, not sure if they have injector humps but it they do trim them down some, put the throttle body that ## running up to it and make sure the hole is centered properly, and if u were capable i would cut that damn plenum off and radius those runner into the plenum floor, not to mention tapering the plenum to get rid of that huge volume and to help air flow into the last 2 cylinders........ i dont like it, bad design and quality IMO (well for n/a anyways).

mike

 

[Slippi84]

ok here we go................ make sure the runners match the gasket along with the flange bolt holes, port atleast the first 3 "inches of the runeners to get rid of that transitoin from runner to flange, not sure if they have injector humps but it they do trim them down some, put the throttle body that ## running up to it and make sure the hole is centered properly, and if u were capable i would cut that damn plenum off and radius those runner into the plenum floor, not to mention tapering the plenum to get rid of that huge volume and to help air flow into the last 2 cylinders........ i dont like it, bad design and quality IMO (well for n/a anyways).

mike

Yeah to be honest I think I'm gonna wait till I turbo the car to even put this on and I think I might try a design like dsm zero as it's the easiest to fab up just mount up and cut everything else off. I'm just curious is there such a thing as too big of a tb? I mean I know everyone will say yes but what are the real downsides to using a huge tb. I mean the car will be boosted so I mean ity shouldn't cause that much of a low end loss and to be honest tracvtion isn't my best friend since i ditched awd anyway so a little low end power loss isn't the end of the world.

 

[InfiniteGSX]

What about that other TB? I forgot what it is.. but its Anodized Red and its like a 70mm???

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*Edit*
Nevermind thats a 60mm TB....

 

[Slippi84]

What about that other TB? I forgot what it is.. but its Anodized Red and its like a 70mm???

idk but I just saw this holley 57mm unit on ebay that looks perfect I might consider. I realllly like dsm-zero's unit but I'm afradit of ill-effects on performace.

 

[InfiniteGSX]

Also he still hasn't figured out what he's going to do about the TP Sensor... Since that TB isn't even made for our car...

 

[Slippi84]

That's like perfect who makes that bad boy?

 

[InfiniteGSX]

Modern Performance!