** I posted this in "Racing and Autocross" and was advised I might get a better response here, si here goes **

What do you think would be the best bang-for-my-buck mod to improve my car in the 1/4 mile?
I have a '92 RS with a 305 TBI/5 speed setup. It already has headers, cat back system with flowmaster, 1.6 roller rockers and cam, TBI spacer, K&N open element, high pressure fuel pump with adjustable regulator (running 13 psi), and 3.08 gears. I also have 2 EPROM's burned .... one ADS super chip, and the other is a custom Track Only chip.

I was thinking a better intake would be next to gain more torque with higher RPM's. Right now, my power band is between 2,000 and 3,500 RPM's. after that, I get better torque shifting to the next gear.

What are your thoughts? Am I doing the right thing by upgrading the intake next?

Thanks,

Thomas.

 

A good set of heads and intake would be perfect for your set up. That would be the icing on the cake. If you can't do both I would go with intake and than heads later. If you get both than your actual TBI unit might not be able to keep up. you might have a to get a 454 TBI or the turbo city one.



------------------
1990 RS 305 TBI T-5
.5" turbocity spacer
Summit 14X3 OpenElement W/k&N
Custom Exhaust
MSD - Wires, Cap, Rotor, Coil
Bosch Platinum +4 plugs
Metallic Red w/26,000 miles

 

You won't need another TBI unit. Maybe bigger injectors though.

[This message has been edited by Keith5 (edited April 28, 2001).]

 

heya,
hopefully you can help me man, havent had much so far.

i have a 91 305 tbi
and you just mentioned that you have a new pump and regulator? howd that go?
any info is appreciated

thnx man

------------------
91 FireBird 305 V-8
no true mods,
ghetto rigged cold air intake,
People dont have a soul, its just something parents made up to frighten little children, like the boogie man, or micheal jackson..."

GheTTo Riggers INC.
We Make Mcgyver look Like Crap

 

if your power drops off after 3500 rpm you have a problem.. look elsewhere in your fuel system or ignition or TPS settings. WIth the mods you have it should pull well into the 4000 rang and you should be shifting around 51-5200

 

hey pablo shifting at 5200?
wow.... i redline 4100..
cam difference?
or?
(thnx fer your other reply too!)

 

Hey, thanks for the replies guys, I appreciate your input.

FiReBReTHa, Sorry, but the fuel pump and regulator were already in the car when I bought it. I've only had it for a little over a week.

Pablo, Pull well into the 4000 range with my mods? WOW, I guess I should start testing things then. Any idea where to start? Are there any good tests I can do to check the components that could cause this drop in power?

My idle has started acting a little funny lately too. I was going to replace the O2 sensor to try and fix it.
It normally idles right at 750, but lately it has been going up to 1400 sometimes.

Also, what is a TPS?

Thanks again guys,

Thomas.

 

Throttle Position Sensor. It's on the side of the throttle body connected to the throttle blades. It sends a signal to the ECU to let it know the angle of the throttle blades at any particular moment.

-Mark W.
'88 SC Camaro w/ 305 TBI

 

Thanks Mark,
Is there a reliable way to test it to see if it's bad ...... Or is it cheap enough where I should just replace it anyway?

When I was under the hood last week, I heard a clicking sound coming from the TBI unit when the key was on.
I wonder if the TPS was what I heard clicking away? Is it normal for it to do that?

Thomas.

 

Your car should idle at 1400 when it's cold and after warm up it'll drop down to below 600 with a stock chip. If it's idling around 750 then your ecm is trying to fix something that isn't working below that (like alternator). Check to see if the IAC (intake air control) step motor is working correctly. Most of the time THAT is what is the cause for a bad idle, the 02 sensor will usually effect your gas milage a LOT. You CAN NOT adjust the TB idle screw when the IAC is plugged in or it'll just self correct.
I think the 3.08's gotta go for some 3.73 posi. One thing to keep in mind about shifting is that you should shift about 400-600 past your peak power output. This way the next shift won't drop you below your power band. So in most cases you should be shifting above 5000. With my mild 350 I shift at 5800 that way it drops into the powerband and speed right up .
I would get an intake if you've got headers, 1.6 rockers. Go with a performer with a TB to carb adaptor plate from Holley. The stock TB should be FINE for a 305. Even 350's work with the stock TB even with 300hp. Definatly do the ultimate TB mods. If you go for a crazy cam swap AND heads AND intake THEN a 2" bore TB would probably be a good idea.
Definatly get an intake manifold, the stock piece isn't worth it's weight in scrap metal. You might want to get another chip programmed and there should be no reason why your car idles at 750 with a stock cam.
Just keep in mind that a 350 is an option so don't get heads with 58cc chambers UNLESS you plan on keeping the 305 for life. Usually I don't recommend getting heads for a 305 because they're usually the only thing (and knock sensor) that doesn't swap over to a 350.

------------------
, Jon (350 TBI!)
91 Red My website

 

Yeah it should pull that high, I believe the stock figures had the horsepower peaking at around 4400 rpm if im not mistaken, Firebretha, your redline should be at 5000 I dunno what kind of tach you got with a redline at 4100.. maybe you got the special edition diesel fuel tach

the clicking sound you hear is the IAC motor just zeroing out.. as long as the key is in the on position and not running the iac is gonna be clicking like that so dont worry about it.

 

Thanks again guys, great info!

So, I took the Camaro for a ride on my lunch break and noticed that in open loop, it does pull well into the 4k range, but in closed loop, it seems to cut back around 3500.
I never noticed this before because I usually wait for the temp to come up and settle before I get on the throttle.

The chip I'm running right now is an ADS super chip, and I'm not sure what this does to my idle.
Sitting at idle with the clutch in, it is normally very steady at 750 RPM. Does this mean something is wrong? Should I try adjusting the TPS as stated in the tech articles?
(BTW: It's my understanding that the previous owner replaced the CAM when he installed the 1.6 roller rockers.)

Where is the Intake Air Control located, and how can I test to make sure it is working properly?

My gas milage right now is running just a hair under 18. I've only had the car about a week now, and I was driving pretty agressively when I took this reading. I figure I could squeeze 20 out of it if I drove it nicely.

On the intake subject, which intake should I be getting for this car? I know you said Holley performer, but I can't seem to find it online anywhere. Do you have a part number? or maybe a web site?

I plan to keep the 305 as I already have a major project vehicle (my '84 K5 blazer) and would really like to do minor mods on this one.

I hear ya on the 3.73 posi, but like I said, one major project car (truck) is enough for me
I am considering getting some sort of locker or limited slip setup, but that will come later on.

Thomas.

BTW: What a great site! I originally found another 3rdgen.org site, and they couldn't answer most of my questions. I found this one a couple weeks ago when I had problems with my VATS system. The VATS article was a LIFE SAVER for me and helped to get my car back on the raod!

Thanks THIRDGEN

 

well. i know the RED' line is higher.
but the car gets to four flat and lagsssss... bad. cant figure it out. before it never made it to four till i changed dis and cap.

------------------
91 FireBird 305 V-8
no true mods,
ghetto rigged cold air intake,
People dont have a soul, its just something parents made up to frighten little children, like the boogie man, or micheal jackson..."

GheTTo Riggers INC.
We Make Mcgyver look Like Crap

 

NO, a manual at normal temperature out of gear should idle at 750. An automatic warmed up should idle at about 500 in drive.

 

GMPP stickers!

------------------
-John
92 RS
-L03 305
-700R4 auto.
-2.73 peg leg
-GMPP open Air Element
-Hypertech Street Runner chip
-Hypertech under drive pullies
-R&R High Flow Catalytic Converter
-Flowmaster Catback Exhaust (with NO tips)
-K&N Crankcase breather
-Kenwood CD head unit
-Kenwood 6x9 speakers in rear.
-Full tank of Amoco Ultimate
-AC delco Oil filter
-The finest of AC delco synthetic oil
-Goodyear rubber on all 4 corners
-AC Delco synthetic differential fluid
-AC Delco antifreeze
-AC Delco Power steering fluid
-Flowmaster exhaust hanger
-K&N sticker under the hood..wouldnt want my K&N to get tossed!
-AC Delco silicon hoses
-High Amperage Alternator
-AC Delco waterpump
-AC Delco thermostat, and housing
-Ac Delco pistons and Rods
-AC Delco L03 block
-AC Delco white paint
"I love my AC Delco"
"Like a Rock"
"Heartbeat of America"
"Bad Bowtie"
"Eat my Shorts" -Bart Simpson (1990)
"Doh" - Homer Simpson (1991)
"FEAR THIS"
"Not Guilty" -OJ Simpson (1994)
"I pity da foo who doesn't drive a chevy"
"Ford sucks"
"GRR HIK" -Crack
"All work and no play makes Jack a dull boy."
Man walks into a bar and says "OUCH" LOL
"My car is white" -CleanRS
"I hate sesame street" CleanRS 2001
"yo momma is so fat...."-CleanRS 2006
"2nd Place is the 1st loser" -NO FEAR
"Ask not what your country, but what you can do for your country" -Jelly doughnut

copyright 1899