RotaMan99

Wondering how the top end performance is for a ITB and manifold setup while not using the pressure wave that is generated in the stock intake manifold setup.

I'll be running a megasquirt setup and ported motor eventually. So just leaving options open.

I don't want comments telling me to swap to a turbo or that there is not enough performance for the money if you have never tried it

BlastinSideways12A

Streetport or Bridge? 6 port or 4?

RotaMan99

I havn't fully decided on the port job. Large street port or BPort on the secondaires only.

Its a n/a so its a 6 port. After all, this is in the n/a performance section

BlastinSideways12A

N/A could also refer to 12As, earlier 13Bs (4 port), or the NA that I am building with TII irons and RX8 rotors ;p

And to answer the question, ITBs would definitely make a difference if you bridge the engine because the form of pressure waves that the stock manifold uses to make the extra power will be reduced and timed incorrectly because the port never really closes so the stock manifolds will be useless.

I'd stick with a large streetport unless you are full bridging. There are some very respectable numbers for streetported 6 port NA engines... (>200whp) I have seen street ported 6 ports make nice numbers with TII manifolds ported to fit the 6 port engines. Something to consider if you are looking for a budget setup.

Even on the streetport, the ITBs would help out at high RPM since you will be outflowing the stock manifolds anyway with a large streetport.

dj55b

iTrader: (2)

I've got more or less the same setup. I have the fuji racing ITB's that bolt on to a sidedraft manifold. I am using the Megasquirt 2 V3.0 board and in the final stages of getting it back up and running. Playing around with software stuff now. All the hardware is done. You can follow up from either here:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/fuji-racing-itbs-finally-d-683967/

or here on the full build

https://www.rx7club.com/1st-generation-specific-1979-1985-18/progress-my-car-pics-d-695200/

BTW my engine setup is a 12a with a fairly large streetport. I'll be mostly comparing the dyno run to my old holley setup which netted 147 rwhp with stock ignition and running fairly rich. Dyno graph can be seen here:

https://www.rx7club.com/showthread.p...highlight=dyno

BlastinSideways12A

^^^^^ WOW ^^^^^

You will probably end up with one of the better 12A streetports out there. I really like your FB!!!

The Holley dyno graph is even impressive, ~130rwtq!!! Ever run it in the 1/4?

I will anxiously await the dyno results of the ITB setup!

RotaMan99

Very nice!

I won't be doing a side draft. Im going to make a box around the horns and pipe the intake to the bumper like which is were my intake is now.

That would be if I can afford it. I Think the restoration of the body and MS ECU will take most of my funds for 2008

dj55b

iTrader: (2)

Thanks for the compliments and yes I do like my car ... she makes me happy so I return the favor ... now that just sounded dirty lol.

But ya i'm hoping with the longer runners, better ignition and control of fuel, I would like to see the torque figures above 130rwtq. The major factor of my toque is partially due to my headers also. Custom SDJ collected into 2.5". Also aiming with the better fuelling and spark, to reach about 160-170rwhp. Port matching is on there too, but not sure how much more that will net though. At that I should be atleast T2 range and faster I think, no turbo no lag, instant acceleration. Plus being lighter. Will be reweighin the car once she's out too.

Further plans for the car though will be Rotrex supercharger, paired with a 2 speed transmission from Antonov for it probably. Unless something else better comes down the road when I'm ready to make those purchases.

Lastly about the 1/4mile run, I did go once ... my first time ever at the drag strip actually and ran shitty times. Still running stock clutch. First run I missed a gear, second run instead of letting it cool, I decided to run back to back, launched from first, and got nowhere. Clutch was just slipping and making sweet aromas. I have a carbon kevlar clutch but still debating wheter I want to put that in or not. I'm looking at the light flywheels from Guru, along with their 5.5" clutches. I would like to make the car as rev happy as possible. Next year I would like to join some sort of training class(es) depending on cost and time.

BlastinSideways12A

Its amazing how light the wraparound manifold is for the 12A in comparison to the stock intake/carb with all of the emmisions. I ran a stockport 12A with a Weber DCOE 48 and full RB long primary exhaust. 11MPG HIGHWAY!!! the car was so rich and the carb so oversized that my car couldn't cruise without stumbling. at WOT the wideband would read around 12:1 at 3500 RPM and by 7 it was around 10.5:1... It would actually start to sputter after 6500 RPM. I coulda been boosting the hell out of it at those AFRs!!!

I ran the car in the 1/4, got a 17.1 @ 78... It was an 85 degree, humid evening in July and my run was about as good as I could have gotten... That was also before I went UP by 2 sizes on the air bleeds and installed the wideband which gave me the 10.5:1 readings. I have no idea how rich it was when I raced it but I'd say that the car would have gone about 16.5 as it was after the air bleeds. With proper AFRs who knows... I love first gens...

RotaMan99

I think I may go with a full bridge except on the aux ports. I wonder how well a ported S5 LIM would work with a custom UIM that would be needed to bolt the ITBs on. This way I can still use the Aux ports? May be to much work for what it may be worth.

BlastinSideways12A

If you are going to bridge the primaries and secondaries I would definitely do the auxiliary ports as well, especially if you plan to keep the sleeves functional. You'll have to cut the sleeves so that the bridge opens which isn't that big of a deal. The acutators shouldn't be any different to hook up than for a full stock manifold.

For a full bridge you'll need 1 piece apex seals... Unless you go with a really tiny bridge on the primaries with no notching of the rotor housings. You have to support the corner piece of the apex seals. And I you also can't use the original 3 piece apex seals in a bridge. The new Mazda OEM seals are 2 piece and work fine as long as the corner is supported.

FC3S.USD

iTrader: (2)

sorry for jacking. But also in the mist of cutom intake manifold, and trying to fidn a good LIM that will work, so might have to make one.

Do you guys know where to get custom Intake flanges, the ones from motor .

I have a guy that can make them, but it isnt cheap. I would want them from mild steal. ( cheaper ) .

dj55b

iTrader: (2)

I believe racing beat and pineapple racing can supply them.

BlastinSideways12A

I STRONGLY suggest aluminum... It won't hold near as much heat. Get some really flat aluminum plate, 1/4"-3/8" and use a drillpress and your stock manifold as a template. Then use a die grinder and then sanding wheel to finish it off. If you can port an engine surely this should be a breeze.

Just my $.02

dj55b

iTrader: (2)

his reason might be because welding steel is easier than aluminum. and also aluminum needs a more expensive welder.

RotaMan99

Well I suppose before making a final decision. Has anyone driven a BP before? How do they drive and act?

dj55b

iTrader: (2)

They depend on how wild the porting is ... if its fairly conservative its not that bad at all.

FC3S.USD

iTrader: (2)

Exactly my reason, I know alu would be much better, Just getting an alu tig welder is way more expensive ( I can get a mig welder ) but for tig I would need to get a shop to do it.

diabolical1

iTrader: (3)

what exactly are you trying to accomplish? you'll need to work that out before anything else.

RotaMan99

Well thias been my DD for 5 years now and im able to get another vehical for a DD and start to restore my 7. Im shooting for over 200rwhp. Im doing this as a project, not as a race car or autox. It has to be able to be street driven but will not be a DD anymore.

dj55b

iTrader: (2)

200whp NA out of our engines will most likely be not that friendly to drive on the street.

diabolical1

iTrader: (3)

not necessarily true. it really depends on how you go about getting it done. i know he's keeping it 6-port, but i strongly believe it can be done on a good streetport. he just needs to get his intake setup spot-on and then back it up with good engine management and a solid tune.

RotaMan99

I was reading up on rx8 rotors some where about, how if you use them you may be able to open a street port even earlier without bridging? Not looking to use them for the higher compression, just for port timing. I have to find where I read this.

Anyone know about this.?

Notes from mazdatrix say that you need to get them milled for 3mm apex seals because the apex seals the rx8 uses warp going over the PP exhaust.

diabolical1

iTrader: (3)

my guess is your reading material was referencing the bevels that come stock on the Renesis rotors. they help open the port earlier and give the motor some low end "ooomph".

i'll wait until some of the guys building older engines with Renesis rotors have reported their findings in terms of apex seal warpage. i'd like to be out there myself, but i don't have the coin to fund that just yet.

BlastinSideways12A

It was a thread that I started a few weeks ago. Here is the link:

https://www.rx7club.com/rotary-car-performance-77/observations-rx8-rotors-older-engines-711515/