Well, I went to E-town for the F-body convention (supposed) and got timed for the first time ever. I've never run the 1/4 mile so my reaction times were slow as dirt. My fastest reaction time was a 1.03. And to make matters worse, my fastest 1/4 mile time was around 16 sec. I have no clue what was wrong, but my car is a lot faster than the way it was running that day. It was about 90 degrees and muggy out too so that kinda hurt. Anyway, the real reason I posted this is that I need help with a few ideas.

Right now this is what I have so far:

Flowtech (cheapie) headers with hollowed cat
Flowmaster series 80 muffler
Taylor 8mm wires with bosch platinum +4's
burned chip from tbichips.com
ram air II hood
Edelbrock open element with K&N filter

I need to make the engine run cooler, cause it was running way too hot that day. Also, I am just running an open ended rear. Would it be wise to upgrade to 3.73 rear? Where's the best place I can find a good posi unit like Eaton or Auburn? Any other suggestions that may help? I know I feel pretty damn embarrassed about these times but if anyone can help it would be everyone here. Thanks for the help.

 

pat,

16.0 for an essentially stock 305tbi is actually pretty good, especially in that heat.

you're right, the first upgrade for you should be a posi and gear.

i'd recommend a 3:42 over a 373. our engines make a lot of torque (compared to the horsepower), a smaller gear usually works best with a torquey motor. you want to get your 60' times down in the 2 second range or better. slp used to sell takeoff posis for 99.00, but they're really hard to find now. i watched ebay for awhile and got a zexel posi with 3.42 gears for 120.00. you just need to look. you also see a lot of posi units and gears in the classified section on this board.

what are your shift points? when you look at a 305 on a dyno, it's completely out of breath by 4,500 rpm. i was at the track friday night and got my best times short-shifting. if you're winding out anywhere past 4,500, you're probably out of the torque curve and would pull harder in a higher gear.

by freeing up your exhaust, you may have leaned the car out .... need to check the a/f ratio.

there's a lot of debate on here over open element vs. cold/ram air induction, but you've made the exhaust evacuation more efficient with your headers and muffler, the next step is to make it easier to get air in. it shouldn't be hard for you to isolate your open element in the ram air hood for cold air induction, giving you the best of both worlds.

look at the tech section for the ultimate tbi mods. i'm not sure how much they're worth, but it's an easy mod that the average person can do themselves. i did them on my car and can't feel any difference, but it sure looks cool.

until you do something with the cam and heads, almost all of your gains are going to be achieved through tuning. the best tool for that (in lieu of chip burning) is a vacuum adjustable fuel pressure gauge. if you click on the top down solutions link at the top of the page, you'll find a complete kit for installing one. it's a good idea.

once that's on, you can look around for a dyno. here in atlanta, dynolab has a thursday night special where they give you 3 pulls for 50.00. with the vafpr and a dyno (with a wideband 02 sensor), you can dial the car in to get the most out of your combination.

you might want to email jprevost and/or njspeeder. they're really good tuners and have gotten some pretty amazing times out of 305's without changing cams and heads, i believe.

my 3.42s are going in next week. after that, the vafpr, then the headers. i'm making only one change at a time so i can judge the improvements offered by each.

 

Use a stock eprom and bump up the timing to 6 degrees running at least 89 octane. Adjust fuel pressure till you get best results and highest mph without any bog. Most likely you'll need to burn your own eproms or have somebody work hands on. Every car is different even if all the parts are the same so don't trust any aftermarket chip.

 

I was thinking about getting a vafpr for my car as well. I know it isn't running lean, it's a little on the rich side, cause I can smell gas coming out the exhaust still even though it breathes a lot easier. With the ultimate TBI mod, I really can't bore out the tbi unit myself, cause I don't have the tools for that. I'd have to take it somewhere to get professionally done. I was thinking about doing some mods to the hood like adding some more fiberglass to try and enclose the open element unit away from the engine air because I know that really chokes it with hot air. I guess I'll have to play around with it this weekend to see what I can come up with. I wish someone around this area had their own eprom chip burner so I could do that. That would help out so much. Are you sure it would be better to go with the 3.42's instead of the 3.73s? I've kinda gotten a mixed reaction from a lot of people that I've asked about this. I really appreciate the help on this guys, even though I do feel embarrassed to post those times.

 

Don't be embarassed to post times. Remeber, there is a lot to take into account, and that your trap speed is a much better indicator of your power. What were your trap speeds?
Also, don't worry about about boring out your tbi just yet. As your mods stand, you don't really need to.
As far as the gearing goes, all I can say is to match it to your planned mods. If you were to leave your mods as is, then 3.42s would be the way to go because you will be shifting at lower rpms. However, if you plan on making more hp at a higher rpms, i.e. via cam and intake and ignition, then I would suggest 3.73s. Also, are you looking for stricktly the fastest quarter time?

 

the track you are at too has plays a big role in ET, the track i have to race at is horrible, i run consistant 16.1 - 16.2, but trap at between 86-88 MPH. i cannot for the life of me get better than a 2.4 60'

 

hey r90,

i agree with you on the bigger bore tbi, but not on the gears.

you've said you're having trouble hooking up. one of the suggestions i was going to make was to try a lower gear. when you're talking about trying to run fast on real street tires (versus dot legal slicks with treads in them), you can lose more in wheelspin than you pick up from the higher gear ratio.

furthermore, a torquey motor does better "pulling" a shorter gear. that's why you'll see 4th gen do a lot better going from a 3.42 to a 3.73, where even a worked over tpi doesn't. lt1s and ls1s don't make a lot of torque.

there's an amazing thread over in aftermarket product review:

https://www.thirdgen.org/techbb2/sho...threadid=84340

it's the longest thread on the board. it concerns a guy named mike crews with a 383 tpi camaro. he's running low, low, low 12s on real street tires and 3.23 gears. it's all in the setup and tuning.

that is an amazing read. mike is a very meticulous guy who does a lot of research before he makes any changes, and he's by no means a master mechanic. i don't think you'll find many people getting more out of the same parts combination than he does.

years ago i had a 70 chevelle with a 400sbc, turbo 350 and 3.31 gears that was running 12.60s on horsepower and 11.80s on nos. that was driving the car to the track and running on L60-15 grand am radials. we switched to 3.73s and i lost 3-4 tenths. even with mickey thompson street tires to cure the wheelspin, i couldn't get it quite back to where it had been. when i put the 3.31s back in and left the m/ts on, i got a best of 12.44 on horsepower. after a lot of head scratching, we finally figured the 400, with all that torque, did better pulling a shorter gear than winding up quicker on 3.73s.

besides, with the 3.31s, i was also able to suprise a lot of caddy's and duece-and-a-quarters in the mile.

; )

 

I agree with you sean. That's why I asked what his plans were. Is he just looking for quarter mile perfomance, or does he do a lot of highway driving, and what kinda of performance does he plan on getting out of the engine.
The general rule of thumb is to cross the quarter at peak hp in your 1:1 ratio gear, i.e. 3rd if auto and 4th if standard. For example, I cross at around 5,000rpm in 4th at 104.xxmph. It's just where I want it to be as that is roughly where my max power is(2bbl tbi is restrictive-hoping to move it up another g with a 4bbl and 1.6 rockers). However, when I had the L03 in there I was crossing in 4th at around 4,000 at 91-92mph, in which case I really think 4.10s would have been more beneficial as they would have had me crossing closer to my peak hp rpms. I'm guessing if I had went with 3.42s, I probably wouldn't have even got out of 3rd.
I'm not arguing at all, even if it sounds like it. I completely hear ya about the 60' times on street tires. What you gain in a posi you could very well lose in gearing. More over, it is very dependant on your engines set up as you said sean.
But once again, that is why I asked pat what his plans were. If he uses it as a daily driver and keeps the engine reletively stock, then 3.42s would be the way to go, because of the torque numbers and mpg. However, if he plans on a cam and intake swap, he will lose lower rpm torque and gain upper rpm hp, in which case I really think 3.73s would be better. They could even be better on gas milage because he's be cruising closer to his peak torque. Gears are expensive and something you really only wanna have to do once, so it is important to take everything you can into account.

 

Well, gears are the next mod I wanna plan on doing besides messing with the timing and chip burning if I can find someone who can help me with that. This is a daily driver, so I believe I should stick with the 3.42's. Besides, I'm already getting around 25-26 mpg which from what I've heard is incredible for our cars. Now, the only problem would be what posi and gears should I get. I was debating between the Auburn and the Eaton posi unit, leaning more towards the Eaton because it's rebuildable. I have heard some real horror stories when it comes to Richmond gears, so I am planning on staying away from them. Anyone have any good recommendations for gears? I guess it would also help if I got the dents taken outta my car, I'm sure that would cut down on some drag, lol.

 

What was your trap speed? 60' ? You said "hollowed cat" are you refering to the stock 2 1/4" cat? Do you have the stock y-pipe attached to your headers? What's the base timing set at? Auto or Manual?

 

My cat is hollowed, or gutted, whatever you wanna call it. My trap speeds were bad, like around 84-86mph. I have a custom y-pipe fabbed up by a friend of mine, running 2 3/4 inch pipes. My 60' times I couldn't get any lower than a 2.3 and that's with street tires. I've never changed the timing on my car, although I really need to badly. It's an automatic with O/D, but I ran the car in D at the track.

 

a 84-86MPH trap speed is pretty good for a stock L03 and 2.3 60' times with 2.73s isnt that bad either, thats just basically how fast our cars are, there is nothing wrong with yours, you are just realizing, like the rest of us, that our cars are relatively slow and without a bunch of mods are going to stay slow. With all the mods in my sig i finally hit a 15.294 and i think i can go alittle bit faster, and when i get the tranny and torque converter in i plan on breaking into the 14s (HOPEFULLY).

Oh yeah, i dont think you need a VaAFPR just yet, wait til you do mods like a cam and intake, your next mod should definately be gears, either 3.42s or 3.73s. I went from a 15.97 with a 2.24 60' time with similar mods to a 15.294 with the addition of 3.73s, posi, crank pulley, 6* of timing advance and tbichips stage 1 chip. Just do alot of research on the boards, everything u need it here.

 

Since you have an auto, your times are maybe just a little slower than average. Gears will help a lot, a cooler t-stat may help some, (helped my car ~.2 sec and ~1 mph if I remember going from 220*-230* to ~170* coolant temps). I wouldn't mess with the TBI itself yet, I got my car into the mid 14s with the stock TBI and fuel pressure, inj everything. Hell I even made 195 rwhp without adding any fuel to the stock settings and fuel pressure at WOT. I doubt the 2 1/4" gutted cat and cat-back is hurting much, I'd recomend a 3" set up.

Focus more on tuning what you have and drivetrain stuff, torque converter, LCA, gears, etc. With an auto you should be able to get the 60' into the 2.1x range easily on street tires and that would give you .2-.5 sec gain in the 1/4 mile.

I trapped 93 mph with the stock cam, intake manifold, and TBI, so don't spend your money on those parts yet. IMO.