From: cbrother@afit.af.mil (Charles P. Brothers Jr)
Subject: Re: Increasing power?
Organization: Air Force Institute of Technology
Date: Sat, 25 Jul 1992 14:39:52 GMT

(Eric Youngblood) writes:


>Does anyone have any ideas on how to increase the power produced by a normally
>aspirated V-8 engine?

>What I've got is a 77 TA w/ the Pontiac 400 cid engine. It was overhauled about
>10k miles ago which included a mild performance street cam (intake .465 / 214 dur
>@ .050, exhaust .480/224 dur @ .050). The heads had a "street-comp" port and valve
>job (whatever street-comp is?). It has forged aluminum pistons and runs at 9.0:1
>compression. The entire crank assembly has been balanced & bluprinted.
>Its induction starts with the open scoop at the base of the windsheild through a
>K&N cotton/wire mesh air filter, Holley 650 vac sec "emission" legal carb. It has
>the original stock Pontiac manifold. The exhaust begins at 1-5/8" Hooker headers
>w/ 3" collectors and includes a crossover pipe. The dual exhaust is 2-1/4" and
>uses high flow mufflers.
>The TH350 is driven by the stock 1200-1800 stall torque converter. The governor
>is adjusted to provide WOT shifts at 5000 rpm. The power is transmitted to the
>wheels through a GM-posi 10-bolt 3.07 differential. Traction is provided by
>Goodyear ST P235R15 radials. Track times indicate an extreemly sluggish 60 foot
>times in the 2 second range, 0-60mph is acheived in ~6.1 & 1/4 mile at ~14.5 secs.

Above is an indication to your low speed problems.  The headers on this
engine will do nothing below ~3000 RPM, in fact they are worse than the
stock manifold at low speeds.  You need to do something to increase your

"off the line" power, this can be done by increasing the stall speed of
the torque converter, or changing the flow curves in the car, and or
lowering the final drive gear ratio.  Another potential source of help
is to go to wider rims (15X8") and tires P255 60 15.  Look at the 
setup that was used on the 1978-81 Trans Am with the WS6 handling
package. On my TA (1978) I use 255 60 R15 Eagle GT tires with no 
problems.  My hood scoop is opened and the transmission was rebuilt
with an 2000 RPM stall speed torque converter.  Additionally, I use
large bore headers (Doug Thorly (sp)) and a high flow exhaust system.

While not completely drag-strip related, see an article written in
Hot Rod, July 1978 pg 67 "One Good Turn", by C. J. Baker.  These
mods to your 1977 will improve its overall handling and some of
the low speed traction problems you might be experiencing.

>I would like to push the 0-60 time down into the high five second range and
>hopefully reduce the 1/4 mile time into the low 14's is this possible or am
>I about at the maximum for a "street" configuration.

>I still have the original 800 cfm Q-jet on the shelf in working order, it doesnt
>get as good gas mileage as the Holley (currently 14mpg city/ 18 highway) but I
>was wondering if the larger flow capacity would boost power? What about intake
>manifold? Are there any that give good low rpm torque but allow better high rpm
>breathing? Is there any evidence that synthetic motor oils can provide a small
>increase in mechanical efficiency?  

>Any experience or suggestions appreciated

>Thanks,

>Ericy

Your Holley is fine, your problems are in the low RPM region.  As others
mentioned lowering your final gear ration will help at the cost of gas
milage.  Oh, my TA has done 0-60 times in 5.6sec and the 1/4 in 14.3
with the tires, transmission, intake, and exhaust changes to a HO 400
1978 TA with the WS6 handling package. 

Good Luck
Charlie Brothers cbrother@afit.af.mil

Newsgroups: rec.autos.tech