pjr

iTrader: (8)

Folks, if I wanted to get a 12A to the 150hp level, what's the best steps to take? I prefer to take a NA road vs forced induction.

My thoughts were to start with header/exhaust, dual webers, intake manifold, and fuel pump. Would that get me to 150? What else should I consider.

By the way, any thoughts on how quick of a 1/4 mile or 0-60 a GS of this level would be able to produce?

Thanks...

rx7gslse

Carb & exhaust... you'll be good.

error402

Porting + Carb + exhaust + fuel system upgrade.

Or

You can slap on a huge turbo.....hehehhehehe.

-Error402

pjr

iTrader: (8)

Can you get there without porting?

peejay

Definitely fuel system upgrade + exhaust (in that order) for starters, then while you're having fun with that start looking in to the induction side of things.

You don't "need" porting to get 150 but it makes the goal a lot easier to attain.

You didn't say what year GS. My 2400lb (with driver) '80 GS ran consistent low 15's which is about 130hp. Setup was far from ideal, too. (Probably had 15-20hp locked away in the crappy intake manifold setup I had )

pjr

iTrader: (8)

I was thinking about an 84 or 85.... are the later years heavier than the early models?

jrios

you can definitely get there without porting...i would start out with r/b exhaust, then fuel upgrade, maybe a holy 600 if not a weber 48 ida...that should get you in the 14's and about 160hp or somewhere around there...i was able to run 14.6 with a stock port 12a, holy 600, and exhaust on an '83 rx7

peejay

Generally speaking, the newer the car they heavier they are. It depends on how optioned-up your car is (does it have A/C or power anything?). All '84-85 cars have a rear axle assembly that weighs roughly 50lb more than the earlier ones (need a scale and some samples of each type to personally verify this) and this is about how much variance there is anyway.

Probably shed a good 50lb off of the car by putting a header on it anyway

error402

Yeah sorry, guys I didn't mean my post to be that you "needed" to port the engine. Just as peejay said, it would easier if you do.

-Error402

iam1ru12

In line with the original question, how much would the following run (installed)? I'm not really familiar with exhaust systems and induction so bare with me please.

• Carb (Weber 48 or Holley 600 - any pics of installed examples?)
• Exhuast System: Header, down pipe, presilencer, muffler ?? (can I get this emissions legal)?
• Fuel system (new fuel rail, lines and fuel pump?)

Will this still achieve sub 15 Qtr miles times on an stock port 84/85 GSL (12A) with A/C and no stripping of the interior. Could this all be done (parts and labor) for $1500?

Thanks!
-Mike

Stepdaddy

well if we are talkin eazy compaired to reliable id say throw a 50shot hell a 100 shot it about as cheep as porting with much better results..lol

so many things can be done to reach this goal but depending on time money and reliable power you want.So again in this world its all about money time and knowledge

Stepdaddy

rotorhead

i've got a 12a, el cheapo header and exhaust, and a dellorto dhla 48..... 117hp to the rear wheels, dyno verified. i'm POSITIVE there are several more ponies hiding in the exhaust.... the pacesetter one i've got is not very flow friendly. this is all on a stock port. my goal for the 12a is 200hp, then i'll be happy. time to save for a street port!

rotorhead

hrm, that reminds me... how much flywheel hp would 117 rwhp be?

SilverRocket

There are more carb choices than that; it doesn't matter as much on a stockport engine which one you pick, the good ones tuned right are going to make similar top end power. Obviously a 48IDA is better than a 45DCOE, but not by a million years.

RB Dellorto setup with full RB exhaust and a good fuel system, along with timing advance and pulleys makes 154hp according to RB.

~150hp is approx. the limit for stockport motors.

As previously mentioned, it's all about the weight reduction; if you have a GS to start with that's a bonus.

With 150hp and a lightened 81-83 GS (no spare tire, jack tools, etc, no ac or anything like that, minimal stereo, superflous engine bay stuff removed, some sound deadening removed, etc) you can run approx. 15 flat in the quartermile.

Jeeze, installed? You gotta remember, these carbs are only available used (unless you get a brand new 45DCOE or RB Holley setup), and will need to be rebuilt, cleaned and tuned for it to work right. This takes a fair bit of time. I'd recommend doing it yourself if possible, if only because it's a hell of lot more fun.

Used Weber 48IDA's tend to run about $600-$900 as far as what I've seen. They're expensive because all the racer guys want them. I wasn't seriously looking for one though, I could be wrong. RB Dellorto 48DHLA setups are far more economical (and just as good for what you want). You can find them for about $300 with the intake manifold and other associated parts. A new Weber 45 setup from Mazdatrix or wherever runs about $750 I believe. The RB Holley setup is similar.


NONE of the systems are anywhere close to emissions legal, especially with an aftermarket carb. You'd have to figure out something custom with an aftermarket cat. BTW, RB exhaust is what you want for best power (racing beat). Don't even consider any of the cheap shitty stuff (ie. pacesetter, monza, whatever.)

Alll you need is a good fuel pump and pressure regulator. IMO forget about the guage, most of them are crap and you don't need one at all to tune fuel pressure. Look at a Carter 7psi fuel pump and Holley 4-9psi regulator, that's what most of us run.

No, probably not. You'll likely be somewhere in the low 15's.

You could definitely do it for that budget if you did the work yourself. It depends what carb you get, what parts you need for it, what exhaust, etc. If you're paying someone I would think that could come up a little short, I dunno. Personally I wouldn't pay someone to do all this stuff.

PaulFitzwarryne

My 12A gives 124-rwhp, which equates o some 150hp at the flywheel. To achive this the modifications are:-

1. RB syle header and exhaust system
2. modified Nikki carb, and inlet manifold
3. K&N air filter
4. remove the air pump
5. good quality plugs

There was no need to change the fuel pump or go for a new carb. At that level of power the restricting factor is the ports. The total cost would be well under US$1500.

If you mean 150rear wheel power as checked on the dyno there is a sudden jump in cost.

1 upgradedfuel pump
2. possibly an upgraded carb and inlet system such as a Weber 48 IDA
3. porting is essential, the real cost as the engine will need rebuilding, unless
4. you go blow through turbo whichwill be cheaper than porting unless youdo your own engine rebuild, you may also get wat with using the Nikki.

if the engine is showing signs of wear it is better to go the porting route, as there is nothing worse than adding a turbo then finding the engine is too weak fo the increased power and requires rebuilding.

You may just get the turbo set-up inside a $1500 budget but have the engine rebuilt/ported wouldbe well over this budget limitation.

PaulFitzwarryne

My 12A gives 124-rwhp, which equates to some 150hp at the flywheel.

I prefer to use rear wheel hp as the measure of performance as you can test the output against a dyno, and measure any furter improvements.Most hp quotes are speculation and estimate without evidence.

To achive this my modifications are:-

1. RB syle header and exhaust system
2. modified Nikki carb, and improved inlet manifold
3. K&N air filter
4. remove the air pump
5. good quality plugs
6. new fuel filter

There was no need to change the fuel pump or go for a new carb. At that level of power the restricting factor is the ports. The total cost would be well under US$1500.

If you mean 150rear wheel power as checked on the dyno there is a sudden jump in cost.

start with the above modifications and add:-
1. upgraded fuel pump
2. possibly an upgraded carb and inlet system such as
a Weber 48 IDA [Paul Yaw says he can modify a Nkki
for 150rwhp but it may be easier on a Weber or Holly]
3. porting is essential, this is a real cost as the engine
will need rebuilding, unless
4. you go blow through turbo whichwill be cheaper than
porting unless youdo your own engine rebuild, you
may also get wat with using the Nikki.

If the engine is showing signs of wear it is better to go the porting route, as there is nothing worse than adding a turbo then finding the engine is too weak fo the increased power and requires rebuilding.

You may just get the turbo set-up inside a $1500 budget but have the engine rebuilt/ported wouldbe well over this budget limitation. depending on the builder start looking at US$2,500.

357

Hey, awesome, this is exactly what I was looking for! Now that I have my car running reliably, I definitely would like to get a little more power from my stock '84 GS (who wouldn't?). The way I see it, at present, the most economical way to achieve 150bhp:

1) RB full exhaust (when you mean not emmissions legal, is that only for states that don't actively check emmissions at regstration?)

2) Modified, or upgraded carb (how can I mod my stock one?)

3) upgraded fuel system

Is this about right, or am i totally off? Also, does anybody know just how much power you gain from a K&N filter?

Paul: Sorry, I'm ignorant, what's the air pump?

357

Oh, and one more thing: how much does a streetport job run?

rotorhead

rotorhead

hrm.... that post didn't come out looking like i thought it would. i guess ya just gotta read between the lines! streetport prices vary.... a lot! if on a budget, you may want to hold off till it's time for a rebuild to do the porting. or be cheap and do it yourself!

WanKeL FD RX-7

iTrader: (7)

On my 83 GS, with the weight reduction, removed sound-proofing, dellorto carb, RB exhaust system, no cats, stock fuel pump, RB intake... I should be around 150hp

so.. it's not very tough to have 150hp in a 12A

Max

RotorMotorDriver

iTrader: (1)

About 130 if its 12% loss...I dont know if thats right...I just remember hearing 12% somewhere...

~T.J.

357

rotorhead: lol; it took me a bit to figure out what you meant, but now that i look at it; nice job

RXcetera

You kidding me?? You should have been there when I was tunning it...

SilverRocket

LOL... yup, I as well wouldn't say the process has been "easy." It took a whole lot of work, time, research, soliciting help from kind and generous friends *cough*RXcetera*cough*, to get to the point I'm at. Of course, you can always go much further

Yeah guys, I just bought Ari's 650 hp FD drag car... so it's not too hard to have 650 hp in an FD

Sorry Max, just messin with cha!