riffraff

i am running a streetported 4port 13b, with carb. i have already put a new exhaust on it, and the car is starting to get quick. eventually i will redo the intake (new carb, manafold). is there much else that can be done for power? any idea what the max amout of power would be? i want to keep it n/a and keep the same port size as i have now.

branca

iTrader: (1)

I'm not sure what you can expect for the end result as far as power, but you may want to consider the following to make your car quicker (which is what it's all about right) :

1. lightweight flywheel, no additional H.P. but allows the engine to rev more freely to quickly reach the sweet spot of the rpm range. (not recommended for drag racing however.)

2. hi performance ignition, such as the MSD 6A, or 6AL, also not necessarily a H.P. producer, but provides a more powerful spark, which leads to better performance, especially in the higher RPM's.

3. reduce drag on the motor by eliminating the fan clutch and replacing it w/ an electric fan, and also ditch the A/C if you can live w/out it.

good luck.......

riffraff

i have not decided what to do yet about the a/c but i was already planing on getting an electric fan. msd is a possibility. and as far as weight reduction goes, new wheels should help me a lot.

i was just woundering if there was anything else that could be done for raw power.

MIKE-P-28

iTrader: (1)

Other than turbos, superchargers or ripping th emotor apart for a porting. How bout some NOS?

peejay

if you run nitrous then it won't be N/A anymore

You can try a 48 or even a 51IDA, and an open header, which will probably get you the most power you can get, but you're really hamstringing yourself by sticking to stock porting.

riffraff

peejay, i donot have a stock port. the engine is streetported.
i have an exhaust header. the next big power thing that i was going to do was the intake. i have not yet decided on what carb though.

i donot want to use nos. period. so that is not an option. i was just curious if there was anything beyond intake and exhaust that could be done.

mar3

iTrader: (8)

WWWHHHAAATTTT?? N/A = Naturally Aspirated = atmospheric pressure is the only pressure available to "pump" air into the engine. Turbos and superchargers are positive displacement power adders. Nitrous is a chemical power adder but the engine is still naturally aspirated because only the atmosphere is there to provide the pressure drop that fills the chambers. If you used nitromethane as a fuel, would that make the engine not N/A? Nein!!

RotorMotorDriver

iTrader: (1)

[QUOTE]WWWHHHAAATTTT?? N/A = Naturally Aspirated = atmospheric pressure is the only pressure available to "pump" air into the engine. Turbos and superchargers are positive displacement power adders. Nitrous is a chemical power adder but the engine is still naturally aspirated because only the atmosphere is there to provide the pressure drop that fills the chambers. If you used nitromethane as a fuel, would that make the engine not N/A? Nein!!QUOTE]

Who said anything about nitromethane? NOS, as stated earlier, is Nitrous Oxide, a very, very different chemical composition from nitromethane. I have a question too, if a car is ported, like riffraffs, then wouldnt that make it no longer N/A because the "natural aspiration" of the engine has been changed? Or is it still N/A because the natural air pressure outside has not changed to force induct anything into the engine? Or am I just confused?

~T.J.

pineapple racing

Branca covered alot of the points. A 48 IDA weber carb w/ 40mm venturies is my choice of carbs. Don't forget about changing the fuel pump. 50gal/hr. is plenty. The size of the street port and the amout of overlap, time the int. and exh. ports are open at the same time make a hugh difference in power. A race motor w/o ceramic apex seals will make about 235hp @ fly. Don't forget about rear end gears. Balance how much hiway driving you do vs. how much gear you put in. The lower numrical gear you install the more rpm you need for the same road speed. A 4.88 gear set vs. the stock 3.90 will make a hugh difference. Some of the 81 and later trannies have a very high (.711) 5th gear ratio. Great for canceling some of the rear end gear. A good way to have your cake and eat it too! Rob

riffraff

i threw in a carter fuel pump when i got my new exhaust, so that is taken care of.. i will probably chance gears (not sure to what though) when i put in the lsd.

the power upgrade will be a little while down the road (i am doing suspension first) but i will definatly have to take a look at the weber.

any thought on dual carbs? worth it? waste of money?

Felix Wankel

A pain to sync, I had a VW with dual Webers, and it sucked to keep tuned....

mar3

iTrader: (8)

No, you're not....it still is...the nitro analogy was brought up because it, too, can be considered a chemical power adder...
---->Rob G., any idea what the HC's at idle (950 RPM) and at 2500 rpm would be for the 48 IDA Weber? Would passing a sniffer be even remotely feasible with it? Glad to see you haunting the halls again!

chubbrx7

if your looking for a race carb i have a racing beat carb for the 13b if interested pm me

PaulFitzwarryne

From the sound of it you have done quite a few mods that should be getting you around the 160hp mark and you are being limited by the input side. I think you are right to initially put some time into getting the suspension right. At this stage with good tyres upgrading your wheels will only really impact on looks.

Most of the minor mods you can do have already been mentioned, upgraded ignition and dump some of non-essentials such as AC.
The impact will still be relatively minor

Going to a light flywheel will improve acceleration slightly but not give you power. At say $700 plus labor is it worth while?

Medium term upgrade the carb and manifold,

The first approach is modify the Nikki along the lines of Paul Yaw's approach. With the average street port and matching headers you should end up with about 210-215bhp of easily handled car with good street characteristics. You are looking at say $500 to get the carb and manifold up to standard.

The second approach is a replacement manifold and carb. A Holley may not give you much more power than a well modified Nikki but Racing Beat do a standard conversion for a 13b streetport. A popular alternative is to use a 48 or 51 IDA which will give you a noticeable increase to 220-235bhp [the latter may be slightly overdoing the size]. The cost is highly variable depending on what you can get locally. There is sufficient expertise on the forum who could advise the best way to set it up.

Rob at Pineapple Racing [above] gave me a good tip, use the road as your dyno. I have measured out a 1/4 strip on a back road as my test track while also use my 50-70mph acceleration time as a measure.

It really matters what you intend to do with the car, for just street cruising I would go with modifying the Nikki, or perhaps have the Weber
as a street/race carb as a back-up if your budget is ok.

riffraff

modifying the niki is always a possibility. kinda depends on cost vs. performance difference between that and a new carb.

what do you think of side draft vs. standard carbs? any thought there

peejay

there is a big difference between nitro and nitrous nitromethane is an explosive fuel with an octane rating of about -100000. (that is a negative number) lower octane = more power. nitro engines typically don't last long

nitrous oxide is basically additional oxygen injected into the airstream. you're artifically changing the aspiration (aspiration = air breathing) of the engine, just as if you were forcing air in with a turbo or blower.

porting doesn't change the fact that it's n/a - you're still relying solely on atmospheric pressure to put oxygen in the engine.

PaulFitzwarryne

Riffraff, Interesting your views of down draft v normal. I have always seen sidedraft as normal. A pair of Weber 45s gives you a straight entry manifold rather than the 90 degree you need on a downdraft. In the end I think it relates to the amount of room under the hood.

In the UK, sdedraft carbs were used in place of the Nikki, either apair of Webers or SUs. Hurly Engineering who produce 3,4 and 6 rotor engines based on 12a parts, use two 1 3/4 SUs in the performance upgrade they still sell. I dont think it matters as long as it can handle the airflow requirements and you have a tuner who knows that Carb.

riffraff

thanks paul. down draft vs. side draft was what i ment to say.

i have plenty of room under my hood, so space is not really that big of a concern. i will just have to look at the two again when i get around to doing this upgrade.

yayarx7

Would the longer runners of the side drafts that come up over the engine give a lower torque curve than the side draft that goes right into the engine or the downdrafts? I would think it would but have not heard anybody else’s take on this.

PaulFitzwarryne

It depends on what you are trying to achieve. An extreme case was some thirty years ago setting up a Mini-Cooper for rallycross. The manifold for the Weber DCOE was so long to get the power where it was needed that the instrument cluster had to be moved from the middle of the dash.

mar3

iTrader: (8)

Please! I just mentioned nitro as an analogy! I wish I had thought of another example now...
Using this analogy, then reformulated GASOLINE which introduces extra oxygen into the combustion process for emission reasons now turns your streetport 12A from N/A into a forced induction engine...whaddup wit dat???

Frankiesaysrelax

As far as naturally aspirated goes, consider this. What does "aspirate" mean? It means "breathe". Thus an engine that is naturally aspirated breathes normally. In other words, it breathes atmospheric air at atmospheric pressure. Thus an engine breathing nitrous oxide is definately NOT naturally aspirated. Anyone seeking further proof of this simple truism should start breathing some nitrous oxide themselves. Automotive grade N2O contains some nasty sulfur compounds that irritate your lungs so don't breathe it. Instead, buy a can of Redi-Whip. Now, hold the can upright and insert the nozzle into your mouth. Exhale, wrap your lips around the nozzle and press on the nozzle to release the propellant (food service grade N2O) and inhale it. Now hold your breath as long as you can. Tell me, do you feel naturally aspirated? Giggle, giggle, giggle!!!!!!!!

riffraff

someone has been spending to much time in the food markets.
but none-the-less that is a good explination of it.

mar3

iTrader: (8)

Guys, naturally aspirated means the atmosphere provides the pressure to fill the chambers. When the engine is turbo'd or super-charged, the atmosphere is no longer the sole provider of pressure, thus the "positive displacement" tag associated with those power adders. Injecting nitrous is not considered positive displacement. It's a chemical power adder. The extra oxygen and cooled intake charge allows the engine to build more combustion chamber pressure which equals more force to spin the rotor which equals more RPM quicker which equals more HP, BBUUUTTT in the end, WHAT is filling those chambers as the rotor spins ever more quickly? The freakin' atmosphere alone! Thus the engine is most assuredly still N/A! Getting back to riffraff's original question...have you gone to direct fire and side-cut plugs yet? Could be another "easy" 10-15 HP right there with the appropriate timing...you've already got a K/N filter, hhmmmmm?

riffraff

actually, go ahead and laugh, but i have not gotten around to getting the k/n filter. i keep thinking about it but never get my lazy *** up to order one.

i have not gone to direct fire. i am on the stock (sort of) ignition. i say sort of because i am not exactly sure. i think that it is off of my old 80. but knowing me , who knows...... how would direct fire affect the hp? and how would i go about making that swap? msd?