I recently bought my first rx7, its an 85 gs, which i got for 1200$( I should have found a better deal). As soon as the car gets out of the body shop (wheel wells and rocker panels are rusted out ) I'm going to start modding it. I've been reading posts on this board for awhile now, and I have a pretty good idea where to start. Rebuilt and street ported motor, full rb sp exhaust, and i think im going to get the stock nikki rebuilt and modified as much as possible by Yaw. The thing is, my goal is 200hp with a carbed na 12a, and I know that setup isnt going to get me close to that. What else do can I do? I know theres small things I can do (removal of airpump, electric fan, underdrive pulley) that will free up some hp, but Im sure that wont help too much. At the moment, nitrous isnt an option, maybe later Any ideas would be appreciated, thanks

 

Bridge-port it. Refer to the thread titled "Bridgeport..." just above this one.

 

Nitrous would mean it's no longer n/a

To the point, you're not going to get near 200hp without porting. A nice street port would get you there no problem, assuming you have a decent intake setup and exhaust setup.

I wouldn't use a yaw carb. you'd need his E/P setup which would run you *lots* more than a weber setup that could make the same power. (it's something like $1500 due mainly to all of the labor involved in porting the intake manifold)

crispeed recently reported 260 flywheel hp on a dual weber carbed street port 12A. i'd have to see THAT to believe it but he's one of those forum guys who isn't known to spout bullshit.

 

what carb/manifold setup would be best for this goal, assuming the motor was street ported w/ rb exhaust?

 

I say either a single Weber 50DCO on a Lake Cities manifold (it's the one that sticks the carb out over the header instead of curling the manifold around 180 degrees), or the TWM setup of two 40DCOE's if you have that kind of money (bout $1000), a Weber 48IDA, or a Racing Beat Holley setup.

No matter what, I'd recommend intelligent porting of the manifolds (enhance flow, not "let's see how big we can make the ports"). But, if it were my engine and not my money, I'd go with the TWM dual-DCOE setup. It allegedly outflows a 48IDA but has excellent driveability, because they're able to use smaller venturis in the carbs, instead of the *huge* venturis typically used in a 48IDA.

 

I find 260hp from a SP 12A extremely hard to believe.

 

Hey, me too. The highest I'd previously heard of was either 227 or 237hp.

But, as mentioned, crispeed is one of those facts-n-figures science guys. If anybody else had said it I'd have immediately claimed BS. (well, there are a couple other people who i wouldn't claim BS... )

https://www.rx7club.com/forum/showth...2A#post1354471

Didn't see his reply to my reply yet... they fab'ed their own intake manifold. That's what I would have done, too, actually. Weber 40DCOE's are a fairly common carb, were used in a lot of carb conversion kits and were found OEM on plenty of Italian hardware. You can find 'em all day long on eBay. Snag a couple of 'em, make my own intake manifold, fab up a spiffy little throttle linkage, and away I go. Well, away I go hunting for jets and air bleeds, anyway...

 

DUAL WEBBERS.... Large SP... INTAKE...AND GOOD EXHAUST SYSTEM... woops caps... !

 

I'm not fond of the webbers, I prefer to stick with the Holley carbs.

~shrugs~

-Error402

 

he said 260bhp and 220rwhp, so 220 at the wheels isn't that hard to believe, is it?

mike

 

I thought N/A was normally aspirated? Meaning, not forced induction? I wouldnt consider N20 to be forced induction...

~T.J.

 

N2O isn't actually 'Forced Induction', but its sorted under that catigory for what ever reason

 

Considering that nitrous is compressed gas, shot into the engine.... I can understand why it's sorted under forced induction.

But say with a holley 365fcm, holley fuel pump, RB intake manifold, RB header, straight exahust w/muffler, no smog crap.... 200hp?

Oh yeah i forgot, of course with a street porting also.

 

Whats the EP setup? Didnt know he delved into EP. What kind of work is he doing? Do you know?

 

Nitrous Oxide is considered a force induction approach, because it essentially increases the amount of O2 available, although pressure doesn't significantly increase in the intake manifold, the results are similar to that of a turbo, or SC.

As far as 260 hp at the flywheel. That I'm sure isn't easy, but not unbelievable.

 

Crispeed likes to rev his engines up way high so I can believe a high horsepower figure from him.

 

N/A = natuarally aspirated

and I agree, its not forced induction.

N/A is just what it means , naturally aspirated ie naturally aspirating "ie naturally breathing"

which it still would be.

 

Yeah, thats what I always thought.
Although, this makes sense.

~T.J.

 

well I gues maybe 90% of the time its N/A and 10% of the time its forced induction.

 

How can nitrous be n/a if it changes the amount of oxygen the engine breathes in? It's not technically forced induction either but the effects are very similar. That's why it's often known as chemical supercharging.

 

This was detailed on the previous incarnation of the Mazspeed forum. I did save the post (Paul Yaw posted there off and on) but I am not anywhere near home right now, I'm 140mi away and I have no car or a license to drive one! I'll post it when I get back, if I remember.

E-Production allows "unlimited" intake manifold porting, OR a 48IDA Weber with 38mm venturies.

What he does, is he does his std. flow enhancement modifications to the Nikki, then takes advantage of the "unlimited intake manifold porting" clause by speding 40 hours with a die grinder converting the manifold to have a plenum, so that each rotor sees ALL of the carb instead of just half. (Like I said, it's labor intensive!) Then carb's metering circuits are altered to work with a plenum manifold instead of an independent rotor style like stock. Altered rather heavily I would imagine, from my experiences with plenum manifolds. I know you've seen my comments on this before...

And yes, while happy gas is not technically forced induction, it is not "natural" aspiration either. N/A mneans the engine breathes nothing but regular ol' air, forced into the engine with nothing but god's own atmospheric pressure.

 

Wow, very interesting PJ, thanks. If you remember to post it that would be cool. thanks. Man thats gotta be alot of work to get a Nikki to work on a plenum manny! Yea I've followed your manny adventures (haha a pun) with great interest!

Sorry your still having license troubles

 

I'm trying to hit the 200 mark i am really close within just about 25. Here is the delima either i go holley and should get the extra 25 or i am thinking of going efi then i probally will get the 25 and with in a few short months could put one of those spinning things on my car you know the ones that make that funny noise when rev them up. any way the 200 mark can be reached by a 12a street port. i was unsure of my motor due to i bought it from a guy i never heard of and he just said it was ported and it came with a warranty. I went back a month later and he showed me the outline for his ports he does. It was the largest street port i had seen. But he only has two stages ported and periphrial. But what can i say i got a little over 180 rwhp and i am still running the stock carb. just jetted.

 

A 45 DCOE seems more practical, maybe C02 injection? save yourself the 1k of gaskets into rebuilding.. for now.