To make a long story short a friend/local shop owner was talking to me one day about building a custom intake manifold. I jumped at the chance. To make it simple we decided to use a manifold built for weber side draft carbs. Then to top it off we decided to go with a big plenum. I decided that I plan to stay NA so we built it around never needing clearance for a turbo/intercooler pipeing.

I dynoed my car on november 8th 2008. The mods on my car are a STOCK ECM, cone air filter, RB header, bonez gutted cat, corksport catback to axel, hks axel to muffler(has an exhaust leak), electric fan, no a/c, and no p/s. My tired 161k mile 1987 rx7 pushed out 142.63hp 117.13trq.

http://myspacetv.com/index.cfm?fusea...deoid=46685475

From there my car was droped off at RaceFab. I pulled off all of the stock parts. Being this is my drift car low end power was not really a concern and I knew id give up some to gain some on the top end.

How it all started



from there we came up with an idea of how we wanted the throttle body to sit and then built a base plate to acomidate it.



It was then smoothed for better air flow since we couldnt get our hands on velocity stacks in time.


Then came the end cap and the stock throttle body mounting flange.


From there the rest of the manifold was built




From there the inkector bungs, air intake temp, and brake booster were all set up


as you can tell i took the time to shine it up alittle

 

From there we put it back on the engine.





The man at work welding the throttle cable bracket.


And all done!


So what did all of this work result in? Well if you remiber low end power was not the goal of this.
As while I am drifting I spend more time on the rev limiter then I do at 3k rpm.
I had hoped for a 10% power gain, and fell just alittle short. I dynoed today. Yes just 8 days later
and made 153.71hp and 113.57trq. Nothing on the car was touched besides the intake manifold. Stock ECU
no fuel control and we didnt even fix the exhaust leak.



http://myspacetv.com/index.cfm?fusea...deoid=46686198

Of course my car is in need of a rebuild soon. S5 internals, and a port job should really bring the manifold
to life. I feel a 9k rpm redline would also aid in pulling more power...oh and something to tune with haha

 

I forgot to add on the last dyno the blue line is the stock intake mani and the red is the custom one.

 

That is a LOT of time and effort to retain the crappy stock ECU and AFM. Kudos for the fab skills, but you really need a stand alone.

 

that's just awesome!! get a safc and i bet there's at least 5 more whp in there.

 

nice work!!!!

 

I am probably gona get a rtek 2.0, but I fully agree there is more in it. The a/f ratio was in the mid 12s so I figure pull it towards 13.1 and i could be sitting close to 160whp.

 

nice work. i really like to see this sort of stuff.

 

Nice work and fab. I think you could have got just as much power if not more if you just ported the factory intake manifold/runners/ throttle body.

 

Actually thank you for reminding me of that. The previous owner had ported the stock upper, middle and lower manifold. I had a feeling it had been done since the intake manifold had been powered coated red.

 

That looks awesome. Nice fab work.

 

Not trying to take anything away from ya, but by looking at the final dyno,
does your new manifold make LESS power up to 6500rpm?
With the stock S4 ECU you really cant run past 7000-7500rpm.
Undoublably, the shorter runners on your new mani would work better higher in the rev range,
but if you only have 1000rpm with more power, whats the point.
If your drifting, wouldnt it be more important to have more torque in all circumstances?

Second question: Did the 6ports work on the original manifold the motor was dyno'd with?

 

Yes, it does make less power untill 6500. Well if my sponsors website ever comes back up I will show you the video of my in car while drifting. You would see why more top end is important for me. Once I get going on the local track my car never sees less then 6000 rpm. So the loss of power is only seen when I am getting started. This was mostly a test to see how much power it would give on the stock computer. I am planning to pull the motor and do a large street port as well as a haltech standalone. I am also reading up on what is needed to be done to reach 9000rpm.

As for the 6pi no they were not working. One of the previous owners had taken them taken out at the local rotary shop.

 

Yeah, you would definately need a built motor if you want to to last very long at 9k.
The S4 rotating gear is probably the wrong place to start also.
S5 would definately be an upgrade since the rotors are lighter and the stationary gears are stronger.

 

ya I actually have a buddy localy who killed a s5 motor. I plan to see if the rotors/gears are salvageable out of it

 

Well I picked up a haltech muhahaha

 

Make sure to post any new dyno results with the new computer/fuel work. Also, Nice fabrication.

 

I'm not trying to be a jerk here, because lord knows I hate it when people come into my threads and just nitpick everything, but I have to say something.

I like the manifold and obviously it makes more peak power. But...

Why retain the progressive throttle body? It would have been a lot easier to just make a flange and use an aftermarket generic throttle body.

Was this the fabricators first time TIG welding aluminum? It looks a lot like my first time and I recognize the issues. Lots of starts and stops, alternating between WAY too much current and not enough, adding filler before the puddle forms and not enough cleaning. It looks like fitup of the sheet metal was not great in most cases either.

I'm not trying to be insulting here and I love that people fabricate stuff. There is some nice attention to detail like the pseudo velocity stacks (which obviously are fine and will be better for forced induction if you go that route) but there are other areas that are far from ideal.

And just before anyone mentions anything, yes, I had some of these same issues with my first aluminum TIG experience.

 

Ya I am actually looking to go with something along the lines of a mustang throttle body now since I will already have to make a bracket for the TPS. Granted space is also at a limit where we have the TB located. haha Ya it was my buddys second time doing an intake manifold and he doesnt really play with aluminum too terribly much. I was gona hit it with the grinder and clean it up but then I thought I would just leave it. Its not everyday you see a na rx7 with a custom intake manifold anyways.

There will be another dyno sheet added here once I get the haltech in and get a tune on it. Granted with the holidays comeing up I hope to get it back on the dyno before my bday in febuary.

 

Hey I like your idea, very creative.

From the looks of your dyno you need longer runners!.

when you go to modify for the mustang throttle body you should add a velocity stack on each side.

I would add another 4" to your runners.

http://www.velocity-of-sound.com

 

You'll find that the Mustang throttle body takes up a lot less space then the stock Mazda unit. That's actually why I went to a 75MM Mustang throttle body with my intake. I would have love to have kept the progressive throttle but there just was not space.

Well, I see it everyday.

With aluminum, he needs to practice the pedal vs. filler rythm. To start the weld, get on the pedal a lot until it stats to puddle and then use the torch to puddle each side of the weld. Put the filler into the liquid puddle with the current still way up. If it's not stabbed into the puddle with authority it will ball up on the end. Now back off on the pedal, move the torch a little and get on the pedal again. The puddle should form more easily this time but a bit of torch movement to melt both sides might still be required. Apply filler, get off pedal, and move forward. Rinse and repeat for entire seam. You'll find that the longer you are welding on that seam, the less pedal will be required to get a good puddle because the piece will have warmed up to a good preheat temperature.

With the Haltech and a good tune, you should pick up quite a bit of midrange and some high end once it's leaned out with a bit more timing. Probably close to the mythical 200HP.

 

here is a good start for a custom intake,long runner, $100. you pay shipping.
for an S6. Thx Ron

 

Oh well that is good to know.

haha well the typical rx7 owner is not as crazy as us to have custom manifolds are they?
I was actually suprised the other day he welded two soda cans together. I know I would have burnt through them like nothing.

shhh you cant talk of the mythical 200hp. I have heard if you speak of it that it will never come around.....damn.....I just talked about it too . Seems afew people think my car is capalbe of comeing close to it.

 

my question is how did you achive 142 whp ? was this before the intake manifold?

 

I'm guessing your friend likes getting sunburns on his hand? gloves would stop that :P Looks great by the way!