How to maximize power out of a stock V8 305 TBI without adding anything.
I want to do some cosmetic renovation on my 92 Bird (ie: new stereo, carpet, seats, steering wheel, paint, tires, etc) Then I want to look at an engine upgrade/overhaul. In the meantime, is the anything I can do to maximize the power of the car without dipping too much into the aftermarket?

 

A good tune up.

 

lol...I am aware of that option....lol... not exactly what I meant.

 

you really cant do much to an engine without physically changing something...

putting some underdrive pulleys and taking the A/C off will free up 15rwhp

 

look for ultimate TBI mods under the tech articals on this site

 

Thanks

 

You will see no miracles... there are a couple things that give you more hp to the wheels... but you are talking just a few. Half the time they are not even worth it.

 

under drive pulleys are horrible waste of money will only see 2-3 hp at your redline and if you drive it everyday you tend to overheat in traffic taking ac off if good idea though

 

Why is unhooking the air conditioning a good idea?

I don't mind adding some things but I just don't wanna change everything. I am just wondering what would add some horses without a major overhaul.
Any help would be appreciated.

 

Trying to add power but stay stock appearing.

DIY computer chip tuning
Ultimate TBI mods
Injector spacer
Dual cat L98 exhaust system from the heads back,
1.6:1 self-aligning full roller rockers,
port matching,
head porting
K&N filter
Smaller crank pulley (It won't overheat)
170-180* thermostat with 2 x 1/8" holes drilled in it

 

underdrive pulleys will NOT cause you to overheat. I have one on and I run at great temps.

 

There are other things that make that kind of car slow, in addition to the engine. And, alot fo the things in the engine that are the limits to its ouptut, are invisible, and as such, not near as sexy as shiny pulleys and chrome air cleaners.

Things I would do to it, in order:

Exhaust, from heads to bumper; L98 single-cat version, with 3" tubing and a high-flow cat
Gears
Torque converter
Rear LCA relocation brackets
L69 air cleaner (dual snorkel cold air); or whatever similar home-made approach will fit the Bird hoodline
Cam (the better stock LT1 cams or a ZZ4 take-out are good choices)
Heads (081 casting; do not waste time, money, or effort on the swirlies that are currently there) with 1.94" intake valves and bowl porting (would not bother with "gasket matching")
Chip tuning (ABSOLUTE MUST with heads & cam swap) and/or raise fuel pressure

Things I would ABSOLUTELY NOT DO: (very poor bang-for-the-buck)

Pulleys (waste of money)
Chrome anything under the hood (waste of money, create leaks, defeat PCV which in turn leads to degrading the oil)

Things I might do, but wouldn't consider priority items:

1.6, or roller, or both, rockers
Injector spacer


Things I know nothing about:

"Ultimate TBI" mods


There's more to making a car fast than making the engine produce more power; and most of the things that produce power leave little or no visible evidence and so are not popular with the shiny-thing instant-gratification crowd.

 

For up to 300 HP stock casting 187 Swirl Port heads are fine. They are not the restriction at your current power level.

That would be the exhaust and the cam.

The Dual Catalyst L98 exhaust system is a 10+ HP upgrade.

The F-body LT1 cam is a good improvement over the stock peanut cam. I would however recomeend the Production LT4 camshaft or the ZZ4 cam. Both with the appropriate springs.

1.6:1 rockers ARE NOT a waste on a stock TBI engine. I have them on a stock TBI truck L05. They cut 2-3 tenths off of my 1/8 mile time alone. I had not even tuned the truck before putting them on.

Headers and 2 1/2" dual exhaust on my L05 gave me a reduction of nearly 1/2 second at the 1/8 mile.

A TBI spacer with a 1" open center, Ultimate TBI mods, and an injector spacer brought the MAP readings back toward 100 KPA up from 90-92. It would drop down to 90 KPA @ about 4,000 and quit pulling. That is almost 3 in/hg of vacuum. I switched to a drop-in K&N filter, leaving the stock air cleaner assembly (not too bad on the G-series). Doing the TBI modifications and open center spacer gave the intake more plenum volume and better flow, allowing the engine to pull clean to 5,000 rpm on stock heads and stock cam. The cut another 3-4 tenths.

After all that, I switched from the stock ECM tuning to my own program. I changed the timing tables, corrected the VE tables, and leaned out the PE a/f mixture, and disable WOT torque converter lockup. Those changes alone were worth another 1/2 second in the 1/8.

The first runs were made at Kennedale and were corrected for weather. They were made with a WOT shift point at 5,500 (too high for a stock cam/stock head L05)

Stock-----------13.03 @ 56.75
1.6:1 rockers----12.78 @ 58.94
Headers/Duals---12.33 @ 61.95
Intake Mods-----11.93 @ 63.58
Tuning----------11.38 @ 66.74

For the next runs, I ran at Ennis on a Test and Tune night.

I adjusted the Governor in the transmission to give me a 4,800-5,000 RPM WOT 1-2 shift. I also had put in a complete Transgo Recalibration kit with the corvette .500 TV boost valve and Corvette 2-4 servo. The rest of the transmission is the same old 110K mile stock unit. It shifted much sooner and firmer.

At Ennis by only changing the shifting of the transmission it ran.

Trans Mods----10.87 @ 69.05 MPH (16.75 @ 86.48 in the 1/4)

I noticed that the 350 just needed some basic maintenance. It had not had a tune-up since I bought it and had a light miss at idle. A slight hesitation around town. Finally it would not hit more than 85% throttle on any of the logs.

1.) AC Delco Wires
2.) AC Delco Rapidfire 2s Gapped @ .050
3.) AC Delco Cap and Rotor
4.) Had the Injectors cleaned and flowed
5.) Set the timing to factory specifications
6.) 170* AC delco thermostat
7.) $$$ Roller timing chain for factory roller cammed engines (Advanced 4*)
8.) MSD 6A box
9) F-body Dual fans
10.) New GM Throttle cable as the old one had stretched

After all of these changes, I made some more runs out at Kennedale.

The best of the night was

10.23 @ 74.85

The last thing I have done to it was to change out the stock ECM for RBob's EBL. I spent about 1 hour a day for a week fine tuning it. Logged to and from work for a week and corrected the tune at night. The throttle response became much cleaner and crisper with the EBL and fuel mileage was up.

Took it to Kennedale again.

The EBL was able to drop nearly 2 tenths off my 1/8 mile time, but interestingly didn't drive the MPH much higher.

10.04 @ 74.96

That is where it sits today. 5,500 lbs, Stock 2,000 converter in the 700r4, 3.08 gears, P235/75/R15s being pulled by a Stock Peanut Cam/ Stock Head L05.

I have a HT383 cam and a pair of Vortec heads sitting in my closet all boxed up, ready to go.

 

Thanks