katkaroto

i know if you convert the na s4 intake manifold to the na s5 intake mainfold, you could gain 20hp.. so what about the na s4 intake manifold to the turbo s4 or s5 manifold without the turbo.. which gain would be more rewarding?

Rx7TyreBurna

iTrader: (1)

The reason you would "gain" with the s5 system is because of the VDI system in the S5 intake.

google mazda vdi. There are a couple sites that explain it.

Turbo manifold..... I haven't heard of any gains. If you aren't going to turbo, S5 N/A would give you the best gains. But you need to find a way of actuating the VDI solenoid.

RotaryRocket88

iTrader: (7)

Just to add, the hp gain with the S5 NA UIM is about 10hp on the top end, not 20hp. Here is the dyno chart showing the difference on Silver88GXL's car.

katkaroto

i am wondering if i close the six ports, and just use the VDI... will that work out or have them open all the time and let the vdi kick in too

Rx7TyreBurna

iTrader: (1)

It would be best to have the Aux open at 3800 and then have the VDI open around 5.8k? i think. I don't remember what mine is set at. all factory though.

If you wire you aux closed, you will lose a ton of power. And, if you open your VDI w/ your aux closed.... i don't know. weird power / no power.

Keep it close to factory. The engineers get paid a lot for a reason.

87 t-66

iTrader: (133)

how do you plan on putting a 4 port turbo manifold onto a 6 port block?

katkaroto

how does that work anyways guys? so NAs are 6 port and turbos are 4 port? wouldnt the 6 port be better? more air equal more power, isnt that how supposedly the rotaries get more power?

87 t-66

iTrader: (133)

yes, na=6port, turbo=4port. you can have the t2 lim modified to fit but i dont see the point unless you are going to put a turbo on.

katkaroto

yea, i would understand that... but do ou gain more with the 6 port or its better to stick with the 4 port?

ramses666

iTrader: (1)

You would gain power with the S5 NA VDI upper manifold only if all of your ports open properly. Making this happen reliably is the inherent problem of swapping the S5 manifold to the S4 engine. The S5 computer operates the ports & VDI with the airpump and computer controlled air solenoids. The S4 has no such provision. The S4 used exhaust back-pressure from the cat/exhaust system to activate the aux. actuators that turn the 5th & 6th port valves.

When you upgrade the exhaust on an S4 you now have a problem with aux. valve actuation. When you add the S5 VDI you have another air actuator valve to contend with that needs a different RPM # activation - 5200rpm - to work properly.
2 RPM switches can activate 2 air solenoids to accomplish this, but the problem is supplying the required air pressure. Some use electric air pumps, I use a mini air compressor and a pressure holding tank with a mini-pressure regulator so that I can pump up my pressure tank and have an ample reserve of pressure regulated air available for the solenoids to work the valves triggered by the 2 rpm switches.

I have a 0-15 psi boost gauge attatched to the output of the mini-pressure regulator and small LED's that give me the status of all the component parts. It was expensive to build - around $500 total. I had to have a pressure tank fabricated - $150 - rpm swithes & regulator & gauge with pod & line & fittings $300. $50 bucks for misc. stuff.

It works great & looks great & I can monitor all functions. My car runs like a rapped ape for an NA.

There are cheaper ways of doing it I suppose, but I'm happy with it.

Ramses666

farberio

iTrader: (7)

^ You spent $500 to get your VDI to work??? It was long and no cliffnotes.

ramses666

iTrader: (1)

Yeah...basically I spent alot of money - $500 - to make all of my ports work exactly like they should.... not really all that much if you think about it... I spent twice that on just the exhaust... half of that - $250 - for an S6 alternator. Stuff costs money... Hell... how much for 4 decent tires? Or 6 months insurance? At least I know what my ports are doing at all times... I don't have to guess or assume they are working. Why have an NA that doesn't work right? So what if I have to jump through a bunch of hoops & spend some $$$. It feels good to make it all work correctly when you modify or upgrade your 7. Why go half-way? It's not like someone can just buy a kit to make the ports all work exactly right. I could put one together but it would be expensive. I'd like to think that I get enough enjoyment out of watching it all work to make it worth the money.

Ramses666

Rx7TyreBurna

iTrader: (1)

Sounds cool. I went for a lumbar air pump, and summit racing RPM switch to activate.

.

$50 total.