1967BuickGS400

Hey guys I'm picking up a 94 Impala ss this weekend and I know there only rated at 260 hp. This is going to be my daily driver and I would like to bump up the hp to around 350hp(crank). Would just exhaust, cold air intake, and a tune get me close? I have played around with ls's but this is my first lt1.

BALLSS

Cat back, CAI & a tune won't get you 90 HP (350 FWHP)

That and a cam would

I got 350 RWHP/351 RWTQ with a very small cam, mildly ported heads, shorty headers, cat back, CAI, 52mm TB, tune when I had my otherwise stock 350 in my Imp.

bowtienut

iTrader: (1)

Yes, exhaust (must include headers), intake mods (you don't need a BS $300 kit!), and a PROPER (preferably dyno) tune will definitely get you close. Also, 1.6 RR's and better valvesprings are highly advised.
I had every "bolt-on" mod you could name short of cam and head work, and made about 370 at the crank. Various dyno runs were well over 300 rwhp, and trap speed/weight calcs more than back those figures up.
Go here and click on "details" for entry #135 for the recipe:
http://www.top-et.com/index.asp?GroupKey=GMBBODY

1967BuickGS400

Thanks for the info.

KW Baraka

iTrader: (7)

F^ck the HP......get some 3.73 gears and a tune.......and go from there.

KW

1967BuickGS400

Anyone know what the best gear ratio is before I start losing mpg's? Being it going to be my daily driver I would like to get the best I can. I'm around 100 miles a day mix city/highway.

BALLSS

if it is all about mileage...3:42 would be the best overall on the B-body, especially on the FWY part, between 3:42 & 3:73 choices

Most do 3:73 as the Imp comes wit 3:08

I had both in my B-body when it was a A4. 3:73 was around 2600 RPM at 65 mph. stock 27" tire. I preferred the 3:42's

cookseyb

Mine (96 SS) is at 2100 at 75, great mileage too. K&N, after mkt exhaust. great trip car,plenty of power. 71XXX miles runs like new... I think the 96 is rated at 275 HP

1967BuickGS400

You still running stock gear ratio? What kind of mpg's are you getting.

KW Baraka

iTrader: (7)

I disagree. I say 3.73's.

Gas mileage suffers MOST when you accelerate from low speed. This is why city stop-and-go driving absolutely kills gas mileage.

But the more gear you run, the quicker you get to city driving speed (less time accelerating) and the quicker you can get to a cruising speed/RPM. Also, a higher gear ratio allows your A4 to hold gear at lower RPMs, especially when you're driving over hilly roads....dropping into a lower tranny gear in that situation raises RPMs and just serves to suck gas like crazy. Combine these factors, and the less stop-and-go driving impacts gas mileage.

It is my experience, that 3.73 gears in the B-body gets better city mileage than the stock 3.08 gears.....and the 'hit' that you take on the on HWY mileage with the 3.73 gears is not as bad as the mileage you gain in city driving.

Ya see.....it ain't ALL about HWY driving......

KW


PS: I find it a bit strange that anyone looking to bump up power by 100 HP is concerned about gas mileage.....but I'm just kinda silly that way......

BALLSS

yeah KW..that's why I said "most" go 3:73

My personal preference though is 3:42. I really liked that gear for my mild bolt on 350 and then my H/c 350. I had a 100 mi a day commute.

I get the lower gear in city will get the car moving easier which should = less right foot (in terms of gas saving)...but RPM will be higher at cruising FWY speeds with a lower gear ratio. All based on how "aggressive" the right foot gets :-). So on the lower gear in city is better concept you pick up 1.xx mpg and Fwy you lose 1.xx mph. so if city/hwy driving is 50/50 its about a wash +/- 1 MPH. More Fwy or heavy right foot (I am guilty of that) the lower gear will = less MPG

and yeah...go fast parts aka more HP is not a way (except CAI & CAT back) to increase let alone maintain stock gas milage.....but the grin factor is better with more HP

SAPPER

iTrader: (10)

LT4 Hotcam, 3.73s, basic boltons with LT headers, 3000 stall = 8.5sec 1/8th NA, 7.6s on a 125 shot and 24-26mpg on the highway. The perfect all-around car.

I shoulda left it alone.

moehorsepower

iTrader: (3)

Do all the free mods, install headers and 3.73 and a good tune, you wont get the 90 HP but it will make a difference.

cookseyb

I get around 20 mpg at 75. I use the cruise control ALOT.. It has the stock rear end in it, not sure the ratio...

1967BuickGS400

I think I'll just try to find some long tube headers and do a full 2 1/2" exhaust, plus get rid of the cats. I will do a cold air intake and a tune that should be good for now. I will just have to find a tuner.

StealthFormula

iTrader: (35)

If it were me I'd do a stall converter, gears, free mods then if you have money left then do headers, 1.6 rockers, cai. I feel a nice converter and some 3.42's/3.73's would wake the car up and get that heavy thing going along a lot better vs. focusing purely on adding horsepower while retaining the stock converter and 3.08 gears.

KW Baraka

iTrader: (7)

This is a fact!

In the Impala world, we usually advise guys to start modding at the back of the car and work forward. A 4300 LB car needs gear before horsepower.....especially given that most significant modifications to increase peak horsepower will also sacrifice low RPM torque.

KW