91RockS

Went to the track last night to see if I’ve made any progress with the L03 305 over the winter/spring. Best time from last fall was a 15.561 sec with 2.371 sec 60’. Mods at that time were open element, headers, and 3” cat back with stock tune.

Mods since then include cat delete, air delete, underdrive pulleys, rear gear swap (3.08 open to 3.73 posi), and prom tuning. Goal for this spring was to break into the 14’s.

Results from last night . . . .

1st pass: 15.550 sec, 2.262 sec 60’ : Missed 3rd gear , learning how to drive again after a long winter

2nd pass: 15.262 sec, 2.195 sec 60’ : Better driving, engine hot from staging lines

3rd pass: 14.990 sec, 2.049 sec 60’ : Better yet. Much improved 60’ time. Goal of 14.xxx achieved. Tweaked commanded WOT AFR after this run

4th pass: 14.835 sec, 2.030 sec 60’ : Best of night. Great launch with little wheel spin. Good shifting.

Timeslips from passes 3 and 4 attached.

I know 14.8 is nothing to brag about, but considering this is on 305 TBI with a stock lower end, cam, intake, injectors, and throttle body, I'm pretty happy with these numbers. I think it's proof that a mostly stock, well tuned 305 can perform pretty well.

Next up . . . . Ported 081 heads, performance cam and intake, high flow TBI, bigger injectors, and maybe an ET that starts with 13.xxx

Casey_Butt

That is nice. Nice going from a mostly stock L03 ...certainly not the slug that many people would like to believe that the L03 is.

I think that with the "new" heads, a good cam and a good tune, you should be seeing some really decent times. A potent street machine.

Fast355

iTrader: (2)

Make sure that you work over the 081s before installing them. Otherwise it is really a waste of time, IMO. You will not see big gains without working them, only use more fuel and make less torque. You will see less low-mid range torque anyway.

91RockS

The 081's have been ported with 1.94/1.5 valves, 3 angle, bowl blend and fluff & buff to clean up the runners. I also plan to gasket match before install. Beyond that, what do you suggest?

bluzman2004

That's great for that setup! I have the exact setup with same exhaust, gears, and headers. Unfortunately mine is an automatic, but that makes me feel good to be tuning on mine.

Gladstoneiroc

iTrader: (1)

What headers are you running? What clutch and tires? I've got a similar setup and I'm shooting for 14's at the end of the summer.

FreeLoader

I'm sorry, did I misunderstand something?

changed heads, cam, intake and injectors? i'd say that's no longer a relatively stock motor...but that's just my opinion.

good track times none the less though.

I've gotta ask though, based on what little I know of your motor and mods, what've you done suspension wise?

I'm assuming a lot here, but it sounds like it might be time to back off the engine(although if the heads are all set up, hey man, cool, throw 'em in) and start working on removing things like body flex, torque movement, that sort of thing.

you'd be amazed how much of a difference a couple hundred bucks and a day under your car can make.

BronYrAur

iTrader: (1)

he says that's next up. Right now its just bolt-ons and gears.

sully91rs

Power to the LO3

Nice work. ur motivating me to get the lo3 into shape.
How difficult was the prom tuning?

BMmonteSS

Wow, those are some pretty impressive times for some mild bolt-ons. Keep up the good work.

91RockS

To answer a few of the questions in the last few posts . . .

Headers are ceramic coated Hooker 2055's. Clutch is still original w/ 95k miles (running on borrowed time!). Tires are Goodyear 235's, G/A's (I think). They've got about 40K on them. They really should changed since I'm down to the low tread indicators.

Freeloader, like Bron replied, the "Next Up" mods in my original post are not installed yet. The motor is virtually stock.

I don't think I could consistenly run in the high 14's in summer heat, more like 15.0 or 15.1. The 14.8 was a really good run with cool temps (~65F), nice launch and shifting, and no spark retard. I don't know how other guys are driving their L03's, but I'm flogging it pretty hard at the track. Shift light is set at 5400 rpm. Seems like some guys on these boards get sceeerd when their 305 gets over ~4500 rpm.

I definitely agree that suspension upgrades are needed with the motor upgrades. SFC's will go in this summer for sure. Suggestions on what gives the biggest bang for the buck after SFC's would be appreciated.

Prom tuning was not that hard, although I still have a long way to go. The answers are all here on these boards if you're willing to look and learn.

FreeLoader

if you can weld, I highly reccomend lca's and the lowering brackets(both from spohn, of course), but that's mostly gonna help you in track times.

I've heard AMAZING results from replacing the torque arm, but that's a fairly expensive part, and again, most help is in the straightaway.

if you're looking for handling too, your best first step is replacing the bushings around the whole car, I did a pst polygraphite frontend rebuild and had wonderful results, it's also one of the best price/handling performance ratios you can do.

I will say two things about it though, at the time I wasn't knowledable at all with suspension at all and bought a new centerlink. don't bother doing that, the one I removed from my car was the EXACT same as the one that replaced it. same condition after 15 years and all. 45 bucks wasted.

the other thing is that while polygraphite is stronger than polyeurothane, it's unneccessary to go with it, and you can expect to hear noise(not loud at all, but it's there) every time you go over a bump or make a hard turn from the day you install it on.

also, if you ARE going to do it, go ahead and omit any bushings for parts you're already buying(for instance, if you were to buy the lca's from spohn, they come with polyeurothane bushings already, so you don't need to buy those), so you're not buying anything twice.

M1tch

is there any way somebody could burn me a chip for my 305?

BMmonteSS

NO

Fast355

iTrader: (2)

r0nin89

Am I wrong in saying you gain no benefits from tuning until you alter your heads and cam or was I miss informed?

Fast355

iTrader: (2)

That cannot be more false. I picked up alot of HP/TQ/Fuel mileage on a L03 truck engine with a full exhaust and dual snorkel air cleaner.

FreeLoader

you can pick up something like 5-10 hp on a totally stock engine in some cases, I believe.

not neccessarily peak, but throughout the range.

BMmonteSS

What we're saying, over and over again in every thread, is that no one can burn you a chip out of thin air that will be right for your particular combo. The only way to get it right is to do it your self. I think TBI chips is charging upwards of 130$ now, you can have all the burning equipment for that much. I'll tell you exactly what to change to equal a TBIchips.com chip. It'll take you 5 minutes, then as your knowledge increases you can tune it better from there.

RBob

iTrader: (1)

91RockS, just want to say nice work. Straight forward bolt-ons with an eye to the future and tuning = good times.

RBob.

banditfirebird

Those are some pretty impressive times for a LO3!

83Chevy_Camaro

Okay, I take it Your times are in the 1/4 mile?!?!

golden

Great passes man

cheese_kake

My friend has a 1992 L03 RS with the 5 speed. It was slow at first because the gas was crappy and the injectors were clogged after sitting for a few years. Cleaned injectors, put in fresh gas and flowmaster exhaust. It is a good performer for the street. Its not in TPI territory, but it will get up and move. I drove it tonite and with some skill with a manual it was quick. I dropped the cluth at 4k and it spun forever, and then I shifted very quickly into second right before it redlined. I experimented all night and I was able to chirp second ALL NIGHT. And it does have decent rubber, dayton 245's not the best but definately not some skinny tires with no tread. I was very suprised I guess it still is a V8 afterall.

Speed_Kills

Very nice

91RockS

Yes, quarter mile. I attached timeslips to the first post.

I never ran the car at the track when it was bone stock, but I'm guessing that it would have run high 15's, or low 16's. With headers, cat back, and good tune up => 15.5. I believe the difference maker for me has been the 3.73 posi swap and prom tuning. Those two things got me into the high 14's. If you hit your shifts, the 0-60' time is everthing, and that's where the higher ratio rear gears really shine. Along the lines of what cheese-kake said, IMO a manual transmission really lets you tap out everthing this motor has (harder launches and higher rpm shifts).

I'm a true believer in what the prom tuning experts on this board have been preaching and I believe my success so far has been a direct result of listening to them. Thanks guys.

DM91RS

Great work so far Rock.............now what cam and intake are going in?

91RockS

I'm still debating that. For intake, leaning towards the Holley Projection 300-66 TBI intake. It's designed for TBI and comes with 2" bores. Most guys using it on this board seem real happy with it.

I've narrowed the cam down to a few choices and have been looking at them in DD2000 to compare. Lunati has a few EFI roller cams that I'm considering, but need to do more research. I'll post up and get some feedback.

In the meantime I'm going to get EBL so I'm up and running with it before the engine mods.

91RockS

Update to the times I posted this spring at top of thread . . . I got a little sidetracked this summer and decided to upgrade the chassis & suspension instead of doing the heads and cam like I had planned. From Spohn . . . SFC's, adjustable panhard bar, boxed LCA's with relocation brackets, 1" rear sway bar, and front steering brace (Wonderbar). Also, Eibach Pro springs, Koni shocks, and Prothane bushings. Suspension mods have really tightended up the ride nicely, but not too harsh. Springs lowered the body about 3/4".

Last night was the first trip to the track with the above mods. I also ran with my exhaust cut-out open for the first time. Temps were very cool (low 50's). I datalogged with WBO2 on all runs, tweaking WOT AFR between passes. Best of six passes was a 14.667 sec @ 93.41, with 1.986 sec 60'. That was about .2 sec faster then I ran in the spring, mostly due to the improved 60' time and a bit more power with the cut-out open. I think the suspension mods improved hooking up on launch.

If I finally get around to swapping out the heads, cam and intake, 13's are definitely within reach for the L03.

DM91RS

Dang he is still alive.............


Glad to hear that things have improved after all the $ and time spent.


[Quote]13's are definitely within reach for the L03[Quote]


You know I'm not a naysayer but if you swap out the heads, cam and intake it really isn't an LO3 any longer is it?

FreeLoader

you could say that with...well every engine made?

I like to think of it as correcting their mistakes...

"they should've built it right the first time!"

DM91RS

*

DM91RS

yeah I know what you mean.........

91RockS

Yea, I kinda disappeared from the boards this summer. Got real busy, so cruising the TGO boards lost out to my job and other projects. Actually I'm lucky to be alive after my wife saw the credit card bill from Spohn! It's all good!

You may be right about calling the motor a L03 after modding, nonetheless, it will still be a 305 with a stock L03 bottom end.

DM91RS

Man.......you got to hide that bill better......


Yep....a 305 with stock bottom end. At least yours has less miles than mine. 212K coming up and has never ran better.

Oh and congrats for the improving times and speed

Casey Butt

I don't have a clear answer for this either, but some of the truck L03 motors were flat-tappet cammed. So in that case the cam and block were different than "our" motors ...but they were still referred to as L03s (unless that wasn't the technically correct RPO name for them). I was thinking that if the block is the same then the motor is still whatever it was originally named. But, in the case of the L03, that isn't even clear-cut.

In the case of my 334 TBI, I solved the problem: It isn't an L03 and it isn't an L05, so I called it an L04.3

FreeLoader

hey i meant to ask you, any of those suspension mods stand out more to you than any of the others?

any you were disappointed in?

forget the 1/4 mile times here, the lower times is nice, but suspension really has to do with overall ride, fun-to-drive-ness(scientifically speaking, of course), and all that other mumbo-jumbo too, not just straight speed.

is there anything you'd suggest that people on here get concurrently with other parts(as in speed parts)?

a distant example would be for people changing to the stock 16" rims(from 15's or 14's) they may want to get the wonderbar and maybe even get the iroc steering box, to avoid rubbing the fenderwells in tighter turns.(personally i've heard about this and don't know if it's true, but i've heard it from people who have done it, and I definitely started rubbing the fenderwells after the change from 15's), anyway, totally unrelated, just covering myself.

anyway, from you I'd be looking for something like "you know, after the full exhaust and tuning the sfr's or lca's really made a difference all the time because of the extra power being made, blah blah blah..."

it never hurts to get an extra opinion from people who've actually got the products, as opposed to people who have read about them a great deal.

also, I don't think I ever got the chance to ask you about this, but did you consider either the underdrive pulleys or the cat delete to make a real difference?

thanks for any physical research results you can give.

91RockS

Freeloader - sorry my post did not meet your expectations. It was only inteded to be an update to my earlier post. I'm not into auto x right now, so straight line data is all I have.

Regarding your specific questions:

I did all the suspension mods at one time, so it's hard for me to say if any specific part stood out as being the best "bang for the buck". Plus, my tires are not good enough right now to push the limits of what the car can do. The chassis/suspension mods I made were inteneded to build a solid foundation for future power upgrades, be it to my 305, or something bigger after that. My opinion is that SFC's are the best mod to beef up the vehicle stiffnes if you plan to increase power. Go with the weld-in's, not bolt on. I really like the Eibach Pro springs in combination with the Koni shocks. To your point of doing certain things together, the springs lowered the car by about 3/4" to 1", which messes up the lca geometry, which results in lost traction and/or wheel hop. The lca reolcaton brackets should be installed when lowering the body to correct the lca geometry.

Cat delete, smog delete, underdrive pulleys, open element, exhaust cut-out . . . it's well understood that none of these things by themselves will produce big gains, maybe a few hp each. But when you start adding them together, along with complete exhaust (headers and cat-back) and a good tune, the gains ARE noticeable and measureable. Without getting into the motor, one mod that stands out is rear gears. Higher ratio gears with posi are a sure bet for improved times.

FreeLoader

haha, sorry for givin you the third degree man.

I was just wondering if you had some opinionated opinions for us.

and you did, so thanks.

DM91RS

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