mperformance

I need help guys...help me decide the following.

I want some serious n/a power like around 200hp+ but I do want to be able to drive the car (around traffic) in the city once in a while for the surprise factor. I wonder if it's possible to do it with a Weber, Holley or a stock Nikki? Seems like half bridge would get it over 200hp. In a streetport is around 180hp.

Is it possible to use the stock nikki carb although rejetted to be able to take advantage of the secondaries and open up only to reveal the bridge ports while at WOT, yet have the car idle perfectly at idle? Will this combination yield over 200hp with a modified nikki?

Another question does anybody have a picture discribing the jets/emulsion tubes in the nikki carb? Please I have already been plenty of times in the Yaw Power page.

thanks

mperformance

ahh BTW the nikki would have the venturis massaged and all the mods...

Maybe even a yaw power would be cool. But I wonder if it will make the 200hp? can it?

What would be a good starting point for a Weber,what weber size 48mm or 51mm, jet sizes, emulsion tubes, etc.?

Ahh BTW forgot to mention it's for a 12A

peejay

Yaw has a bridge ported 13B in his pickup and it makes 232hp... I *think* he has one of his massaged Nikkis on it.

The thing with bridge is you really need a free-flowing exhaust for it to work, meaning loud and/or expensive.

mperformance

don't really care about it being too loud...I got the whole rotary deal with exhausts down packed...it can be made a bit not that loud with the proper setups...not that expensive just like $400...and with multiple freeflowing mufflers...

repuguru

Yaw told me he had a Hitachi on the shop truck. Why??? I am not sure. I was having him build the current induction system for my street ported B motor and wondered why he didn't have the same.

Maybe he does now.

He also implied that 200hp is obtainable from one of his carbs. But a streetported motor better have the right ports to do it.

A bridged motor will do it.

yayarx7

I would think that 200hp should be theoretically attainable with a bridgedy and a modified Yaw nikki. It would probably be more livable to run a street port 13b to get that number though.

85RX7GS

iTrader: (1)

What is Paul Yaw's website address again?

WackyRotary

Dude, go with a full bridge, you won't regret it. I drove mine in traffic, but if you are planing on driving more then 30% in traffic, maybe a rotary is the wrong engine to be using. I was following someones rotary without cats and nearly suffacated! LOL! I feel sorry for people behind me now! But seriously, a full bridge kicks ***!

mperformance

Wacky the thing is...I don't want to spend on carbon seals, nor do I want to be bridge all the time. Get it? the idea is to surprise people but yet be able to drive a bit on the street. I don't drive my RX7 all the time...maybe like 10% of the time (it's actually just used for racing)...so really loudness or drivablility issues are not a problem.

I just want to have like 200hp (flywheel) with a 12A, nikki carb...be able to idle safely at less than 1000rpms be able to say I got A/C and yet outperform most of todays cars on the street.

My goal is not that far away I would say...I have had streetported RX7s (12as) and yes they can perform but only close to like 180hp so I want that little edge now. 200hp + would fit my bill for now.

Directfreak

iTrader: (2)

For a quick solution without opening the engine up.

a Nitrous Oxide System will do it for you.

A wet 50 shot should be more than adequate and safe.

mperformance

Direct I have 3 spare engines...I am seriously considering that alternative...

I am just concerned about the fuel side of the whole equation...How would I tackle that...I have a carter fuel pump 7 psi ...would you recommend a bigger pump and run two pumps?

Directfreak

iTrader: (2)

For a 50 shot you shouldn't need two pumps. For the fuel you need volume more than pressure.

Get info from someone who actually uses NOS. I don't really care for it much. But for safety I do know its about 1 part NOS to 3 parts fuel (3 to 1).

Good luck and let us know how it comes out. I might run NOS with my setup "just in case" I run into Racer "X" and money is on the line in the future.

REVHED

There's no way a half-bridge will idle at 1000rpm. Even though the secondaries are closed at idle (assuming you have a 4-barrel carb) the intake charge still "sees" the exhaust port through the eyebrow port on the secondaries. I doubt it will idle much lower than a full-bridge. Even my large extend-port with IDA doesn't really like to idle much below 1400rpm.

mperformance

Are you sure REVHED?

But then what would be the idle for a halfbridge? is it bareble? as long as it is low enough I'll be happy.

REVHED

A half-bridge has almost the same brapping idle as a normal bridge-port. My quess is that it could probably idle at around 1500-1600.

Whether it's bareable is a matter of opinion. Personally I love the bridge idle and would have no problem putting up with it.

yayarx7

http://personal.riverusers.com/~yawpower/

mperformance

Damn it I though a halfbridge would have a normal o close to normal idle...I don't want the brap brap brap...I want to surprise people... ohh well...

back to plan A...

Directfreak

iTrader: (2)

streetport
stock (heavy) flywheel
NOS

You'll be over 200hp with no one the wiser.

mperformance

yeap Direct it's going to be streetported...and Naussss...two bottles ..I need two bottles...my car topped out at 140mph today I need Nauss

But yeap seriously...it's going to be streetported and NOS for sure.

thanks guys....now to make some money to pay for the mods.

peejay

heck even a decent street port will have a brap-happy idle...

mperformance

damn peejay must be a big *** streetport man...hahaha....never have had a streetport brappin on me LOL!!!

Directfreak

iTrader: (2)

But not nearly as bad as a bridge.

My old SE idled at a fine tuned 1100 rpm with the Street port.

Many "stock" ports out there are so badly tuned that they idle even higher.

But PeeJay is right, it will still brap a little (and idle less smoothly.)

That's why I recommend the stock flywheel to smoothen out the rougher idle (worked for me)

mperformance

yeap or turn on the a/c...

peejay

Yep! Just increase the load so that there's less manifold vacuum.

The brapping is caused by exhaust gases drawn through the overlapping intake port and into the next chamber. The more overlap you have, the more exhaust gases will bypass at a given intake manifold vacuum.

A stock port engine will get brappy on the choke under certain conditions, too - manifold vacuum is high enough and the mixture rich enough that combustion gets unstable and goes into the familiar cylic misfiring that we know and love That's part of why Mazda put the shutter valve on '81-up carby models... without it the engine bucks when vacuum is very high and RPM is low enough for combustion to occur... which turns out to be in the sub-2500 range on a stockport, right where you are when coasting in a higher gear.

mperformance

yeap peejay I got that old style carb installed in my car now and I can play with the mixture and get an awesome brap brap idle...

tooo bad it's not the real deal...it's so slooooooowwwwww

damn I need porting badly.