BrewerBob

I'm sure it's been asked a 1,000 times already but I don't want to search "carb" and read 999 threads to find the one that is what I'm looking for.

I have a street '85 GSL and a track '85 GS. I am going to switch the rear ends and gut the track car. Since it will be IT-7, it has to stay stock within those rules.

The street car will be a daily driver. What can I do to it that is cheap (<$1,000 preferrably <$500) that will improve the performance. I'm looking for hp not handling. I don't want a drag strip car but I do want to be able to beat the Escorts off the on-ramps.

I live in SC which means both headlights don't even have to work much less pass emmissions and vehicle inspections. I'm going to unplug the cats and loose the muffler altogether (if it's not too loud).

A friend suggested a carb but recommended some brand that I haven't heard of before. It wasn't the Holley or Webber that everyone here seems to like. Here it is "Hmmm... I'd go with a 2-barrel like a Dellorto or Mikuni".

So, what else can be done cheaply to a 7 to make it quicker?

79+80+84_rx-7

find a used racingbeat exhaust unit....... best increase....

brianw

I think Carl and Inittab are working on a FAQ dedicated to this. I can't wait

BrewerBob

Wouldn't RB be more restrictive than no exhaust? This is SC. All I really need is a straight pipe to get the exhaust out of the engine bay (cooler temps).

I could probably use an improved intake and exhaust manifolds to help open things up.

BrewerBob

This thread https://www.rx7club.com/newreply.php...postid=2346081 says something about removing the air pump...

The belt on mine broke while I was tinkering one day and it ran like crap. Replace the belt and it was much better. It was smoking, sputtering, etc.

Is the air pump removal part of another improvement? Jetting, smog, intake, etc.?

brianw

Yes, Look for Rat's nest removal.

BrewerBob

That is one improvement that I'm not sure I'm willing to do. Not only is it a lot of work but it looks like something that will kill the car if not done right. The car runs now, I want to keep it that way!!

cosmicbang

You need some kind of header whether you buy the RB or make it yourself. The "streetable" RB header is very good; the metal is much thicker than cheaper ones. They also have another racing version for running long primaries. The RB presilencer does a good job of getting the noise volume down without restricting the exhaust (it is straight through-no baffles). I have used the RB header and the presilencer with straight pipe back and no muffler, which close to being a straight pipe and not that loud either. There are also RB "prima-flow" mufflers but they add some restriction. Any of those carbs you mentioned will work, and SU's are also an option. They each have their merits.

brianw

Yea, I was thinking the ame thing but had too many vacuum leaks so I wanted to minimize the vacuum lines to help. Worked good but did take some effort. I got a box full of extras now!

Rx7carl

Yea Brian, he must have read your mind huh? While I see what can be dug up, Lets do this. We'll pick a topic for the week, sticky it and get a handle on it. Since Bob started with power mods, this will be the topic till we wear it out. Imrenaming this thread and gonn sticky it. Hopefully we'll get enough info to make it part of the archive.

Rx7carl

Well I'm gonna take the "system" approach to improving power. SOme ideas/concepts to consider.
1- simplify the engine. Lowers the chance of a malfunction robbing power.
2- breathing. Like a boinger, anything you can do to allow it to breathe more efficiently will increase power. Adding to breathing capacity will increase power (but at the expense of low end power).
3- Parasitic drag, friction. Removing anything that is robbing power that could be used to drive the wheels doesnt ADD power, but allows that power to go where it needs to be.

cosmicbang

If you change the carburettor out you don't need any of those hoses, relays, air pumps, valves, water bottles, etc. Just maybe spark plug wires, a fuel line, fuel return line, throttle cable, choke cable, vacuum advance hose, power brake vacuum line, and oil metering lines to the carb. That's it. IMHO it is easier to start from the minimum of what the engine needs to run and add items rather than trying to selectively remove hoses and crap from the POS stock carb. But each to his own...

813KR$

Street port, headers (isc are better than RB, because they dont start to bend back as soon as the RB), K&N(and either punch mad holes in the stock air filter cover or buy after market RB), deffinetly get rid of air pump and rats nest(very easy), Richen the jets in the carb, Good muffler no cat, convert to Direct Fire Ignition. If noise is not a problem get a flowmaster. RB under drive pulley! Give a little more power, but allows you to rev over 5500 and hold with out cavitating your water pump! Then an elec fan is always better!

What have I forgot!

BrewerBob

I agree with you (sort of). If I were starting from scratch, I'd never have the rat's nest. But seeing how the car already has it, I'm for leaving it. If it ain't broke, don't fix it. Especially if you've seen the things I've taken apart to "clean", "inspect", or "improve". Sometimes it works and sometimes its a fatal operation.

Anyway, if replacing the carb will get rid of all the rat's nest crap I might do it but no one has shown a gain from just the nest. Like the write-up says, "...all that work and for what? Cleaning the engine bay?!"

cosmicbang

It was pretty easy to take off. Like anything else tearing apart is easier than putting together.

No I would not try to remove any of that stuff and still keep the stock carb, though I hear it can be done. My opinion of the stock carb is very low, and I wanted to install a better one for performance and ease of maintenance. I do not have to worry about emissions. Therefore when I took off the old intake and carb all that other crap went away along with it. I just bolted on new intake and carb, hooked up the fuel lines, vac advance, brake booster, oil metering lines, and throttle and choke cables. It was simple compared to mucking around in a stock setup. Result along with the RB header is impressive and you don't even have to take apart the engine.

Rx7carl

Well, ask any Spec-7 racer about what hp the air pump sucks from the engine. Free hp too. Is that cheap enough? Also, if your going without cats, the air pump is unnecessary drag. Also the emissions become useless. So for free, we have simplified the engine, and freed up some hp.

Rx7carl

ANother drag reducer. Switch to an electric fan. Look at the threads on the Taurus/Sable fan. $15 at the junkyard. RB underdrive pulleys will also free up some power from the accesories. Around $100 for the set

cosmicbang

Yeah I figured it went without saying take the air pump off since there is really nowhere to plug it in after those mods. These cars definitely don't need power steering either, and for 2 summers in the 80's I lived in myrtle beach driving an FB with no air conditioning. Not that I would do it again, but it does suck HP.

So if the only accessories are the puny alternator and water pump, and the fan is electric, would underdrive pulleys make any difference or be worth it?

Rx7carl

Small difference, not noticeable on the butt dyno. But OTOH, a bunch of small improvements add up.

brianw

Just got done with Putting on an electric fan. No idae what it came off (my friend had it lying around). Runns MUCH smoother gains R's faster and I had toi use the steering wheel when I hit second! Biggest improvement thus far.

ray green

iTrader: (14)

Carl's got me convinced on the air pump, once I get a block off plate, one of those little fan belts and a weekend, out it goes (and Carl gets his beer). But I'm still not sure about the rest of the "rat's nest". Things like idle compensators, etc sound like they just might do something useful. And if there is no HP to be gained, I kind of like the retro look.

Ray

brianw

Mine felt faster after I took all that off. Could ahve just been the air pump though. Of course new wax make me think I'm cutting the air better!

BrewerBob

Alright you two....

Give me the proper order of operation....

1) Unplug cats
2) RB exhaust
3) rat's nest
4) new carb
5) pulleys

Should I bother unplugging the cats or chuck them and use a straight pipe? Can I do just the air pump (no messing with cats, intakes, carb etc.)?

Cosmic,
There were a couple of 1st gens advertised in the weekly trader. One full car and one minus the tranny. Both for $400. Was that you? You might want to check it out.

cosmicbang

If it was me I would first upgrade the exhaust (typically the header, presilencer and muffler) and remove the cats in one foul swoop; that is probably the easiest on your list. If you plan to add the RB exhaust why muck around with the cats in a separate operation. Remove the air pump also when the cats go away.

I have not removed a "rats nest" by itself, only in the process of replacing the carb so someone else can comment on that. Adding a new carb is fairly straightforward but you need to allow for down time in case you have questions, or for getting it tuned and running properly. (Since you mentioned daily driver.) Pulleys will apparantly give some benefit but I have never seen any dyno figures all other things equal it's probably minimal, and there may be drawbacks. Electric fan was the other item suggested.

cosmicbang

No that wasn't me I sold mine a couple years ago. Cheaply also and I still regret it. Don't tempt me I have no place to hide any extra cars at the moment, lol