DOC Race intake manifold group buy discussion


Oct 18, 2016

This is a DOCRace prototype manifold which will be getting the cast treatment and some improvements in the $1200-$1500 range.

Here is what he has to say:

I have been working on this so don't think it has been forgotten. The first couple manifolds that were built went to Tony Vargas and the DOC Race shop car. We both have confirmed that it does make more power than the factory manifold which was my biggest concern entering into this. I'm just not a fan of performance parts that only look cool with no real testing. My second concern was looks. How do we get away from that hidious factory looking manifold? You can have the cleanest engine bay but then the factory intake just kills it.

I went to town on design with the knowlege I have of building a bunch of 2J intake manifolds. My undertstanding of what actually works and what just looks good. There were a couple limitations on these motors that I encountered. First one was that the oil filter housing is smack dab right in the way of where that first runner should be. The problem with that is now we have the front runner having to be offset just slightly which makes that runner just slightly longer than the rest. Now there are a couple ways to see this. That front runner is just slightly off so for normal car you "probably" will not see a difference or see any damage. The way I see it is if you are trying to tune a 1000hp car you want everything to be perfect. Hell if you are tunning a 600hp I would want everything to be perfect. I've never build an unequal length runner intake manifold and I will not start now.

So option 1 is to offset the front runner, very simple to do and would make things "look" normal but may cause engine damage. 2nd option is to offset all runners which as you guessed is 6 times the amount of work compared to option 1. What did we do? Of course we offset all 6 runners to keep them 100% equal length. We used 2" tubing which is what is used on our 2J manifolds that makes 1000hp all day. On top of that I have designed a plenum with volume to support well over the HP range that anyone will need. This is what I have come up with if you haven't seen it.

IMG_7716.jpg File Jun 24, 10 57 16 PM.jpg File Jul 27, 9 41 44 AM.jpgFile Jul 27, 9 42 08 AM.jpg

So where does that lead us? Why aren't these being offered to be sold? After making the first couple manifolds I have realized how complex these need to be to be done right. Offsetting all runners is very time consuming but is necessary in my option. These things aren't currently offered because they would end up costing somewhere around $3500. I just don't even want to be a part of that.

What I am going to do is have these manifolds casted. I think it is the most economical way. I have can them manufactured faster than they can be sold (seems to be a problem in this market) and there will be no performance losses. In fact because they will be casted I am able to modify the runners to start out as 2" and taper to 2.5" as it reaches the plenum for a velocity effect. This is something that is impossible to do if hand fabricated. I expect there to be an even better performance advantage from the original fabricated design. The manifold from coasting would then be fixtured on a mill to have flat flange surfaces and incorporate factory O-Ring sealing. Here is what it looks like on 3D.

File Oct 21, 9 47 40 AM.jpeg.jpg File Oct 21, 9 47 50 AM.jpeg.jpg

So far I have invested a good amount time and funds trying to make this happen and at the same time not trying to let too much info leak out. The majority of R&D has been done and we are just a couple weeks of having a prototype manifold ready to be test fitted on the shop car. Once it has been fitted and I give the OK it's time to have the tooling made so I am trying to get a head count of who would be looking to purchase one of these.

The best part of this whole thing is that these manifolds are not going to cost you $3000 haha. I haven't set a solid number quite yet but we are going to be anywhere from $1200-$1500 depending on how many people are in on this group buy and what curve balls I am thrown down the road. It would not require you to put any money down at this point. Once the prototype is fitted and we are good to go on making the tooling I would then ask for a deposit of $500 which is not refundable unless I am unable to deliver on my part. If you are interested please reply to this post with your email address or send an email to [email protected] Please include if you are interested or ready to make a deposit. Once ready I will inform everyone where and how to make the deposit.

This is what will come with the kit:

-Intake manifold- options of colors for powder coating.
-Bottom mounted port injection with included -6an fuel rail.
-3" charge pipe going to intercooler. I suggest going with an AD-Engineering that is setup for 3" outlet.
-provisions for map sensor and (2) 1/8"npt fittings

Any questions please feel free to ask.
And here is a mustang dyno on the IM:
File Jun 23, 8 29 40 PM.jpg

Who has/will be stepping up to the plate for this?
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Reactions: Twisted Tuning


Nov 3, 2016
I just don't think my 5862 setup qualifies enough power to need this. I know most people running a ST setup run a bigger turbo though, and as we've seen, the power difference between a 6266, 6466, and bigger aren't very much and I believe this starts to be one of the limiting factors. So the want should be high for this.


Nov 3, 2016
I agree, it gets rid of some of the things that aren't exactly "flawless" but I do think once you hti a certain power point, our stock intake manifold becomes a choking point.


New Member
Nov 5, 2016
Cincinnati, OH
Using the sandwiched PI setups currently being used brings about increased number of potential failures and boost leaks. Not saying it's likely to happen but there's always a chance. This is brilliant!


Oct 18, 2016
Would PI meth even be worth while if you're already running PI e85? I wanted to try and find a way to stack PI e85 and nitrous but I'm not sure what would work best for implementing that.
People don't like nitrous but personally I do. I think the issue you run into again is fuel unless you intend on a more complex wet system with fuel cell or something along those lines. I'd like to run a small shot.
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