2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Sper AFC RPM Reading

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Old Apr 16, 2003 | 10:54 PM
  #1  
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Sper AFC RPM Reading

I Need to add additional fuel to my car.. 89 gtu k&N intake new style racing beat catback... NICE!!) I think i have decided on the Super AFC.. However.. Like many other things, its RPM dependent... Does the readout on the AFC match the actual RPM of our cars???? or how do you get it to match??? (I had to set my summit racing switch to four cylinder and then monkey with it untill my six ports open at 5,000) Or does it hook up in a way that you don't need to worry about it???

Thanks
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Old Apr 16, 2003 | 11:09 PM
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it hooks in fine... lots of people use it.

but you will probably be leaning it out. not adding more.

edit: just saw you only had a catback. thought it was full exhuast. s-afc is probably a waste. spend $300 on headers instead. more power gain.
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Old Apr 16, 2003 | 11:54 PM
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I'm running a bonez midpipe as well,, no cats.. headers.... thought about it.. but unless you want to put a carb on it... it only gets you about 2 more HP over a straight pipe... What i really want to know is if the RPM on your tach matches what is on the AFC
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Old Apr 17, 2003 | 12:25 AM
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yes. you just set it for 4cly

mine is off by around 300rpm though at higher revs. most probably are. the Afc will be right. the tach is off.
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Old Apr 17, 2003 | 12:35 AM
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your claim of only gaining 2hp with a header... is that peak or over the whole power band?

You don't need to answer that because if you ask or run against anyone with just a header and all the other same mods you have, I bet you would get smoked.

Even the biggest critics of headers gains will tell you the header is worth 5-7hp top end and considerable gain in the midrange.
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Old Apr 18, 2003 | 09:08 AM
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Thanks for the responses To the S-AFC!!! I'll be purchasing one soon.

As to the header.... In HP gains... I'm talking about overall gains in a 6-port motor... Dyno results show that when using the same cat-back with a header system as compared to using the thermactor and a free flow mid pipe... WITH no internal engine mods... the Header will produce about 1-2 HP over the midpipe and thermactor...

SOOO... Unless you are planning to switch to a carb setup, street port the motor, or add a supercharger, you are only going to get about 2 HP or so with a header as compared to running a cat elimination pipe.

Lemme tell ya.. that thermactor acts as a presilencer as well, even for 5 HP, the noise of a full header just isn't worth it!!

ALSO.. I have an 89 N/A.. 89N/A exhaust ports have a steel insert in them that makes porting the exhaust almost imposible and if its a 6-port engine.. porting the intakes is not cost effective because you can't take much more material away because of the design of the 6port system.

SOOOo I'll agree that a header make sense for a modified 4-port motor OR if you're feeling really froggy and want to slap 4-port rotor housings in a 6 port motor and modify the exhaust port!!!
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Old Apr 18, 2003 | 11:36 AM
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I hope to god it doesn't rain sunday, because I'm so sick of people saying the only way to make power is with a damn four port. (car club has a dynowars contest I'm entered in)

Ever try removing the inserts from an n/a's exhaust ports? It's not all that difficult with a sawzall and die grinder.

6 port side irons have the timing duration of a PP. The only restriction is in the center iron and I pitched that altogether in favor of the better s5 4 port casting.
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Old Apr 18, 2003 | 12:56 PM
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honetly... I took one look at those exhaust inserts and said.... NOPE!!!! I only got one set of housings.... not gonna f' with it!!!
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Old Apr 18, 2003 | 02:47 PM
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My s-afc matches my Tach exactly. Guess I have a good tach. Some people say it doesnt match when they install it, but the s-afc's reading should be the accurate of the two because of where it gets its reading.
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Old Apr 18, 2003 | 05:06 PM
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Doobie dooobie dooooo
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Old Apr 18, 2003 | 05:14 PM
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Just wondering why you are adding more fuel at all. YOu don't need it.
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Old Apr 18, 2003 | 07:24 PM
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Originally posted by 1987RX7guy
Just wondering why you are adding more fuel at all. YOu don't need it.
Don't you think that's for the wideband to decide?
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Old Apr 18, 2003 | 07:25 PM
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At peak RPM's, the tach reads about 300 rpms higher on my car. I haven't verified at normal speeds, etc........
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Old May 5, 2003 | 02:05 AM
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Right... just hit it with a wideband..... TOOO much fuel... its dropping below 12 on the wideband at around 7k
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