Rainmaster

Hello all,

So I have a stock 1985 LG4 and I'm preparing to give it a much needed upgrade. I'd like to get an idea of what sort of power gains I should expect. I already got myself an L69 Dual Snorkel, now it's time to take the next step.

Here's what I'll be putting on:

Hooker 2055 ceramic coated headers and y-pipe
Catco 3" hi-flow cat (9118)
GMMG 3" Catback

I'm fairly certain that my car will sound a lot more bada$$ with this setup, I just want to know if I'll have any sort of power to back it up. I know it won't be that much, but it should be much better than stock. I hear some say that a 3" exhaust on an LG4 can help it gain somewhere around 20hp, but there are a few who say that you can get up to 40hp. What do you guys think?

I plan on getting a performer intake and a comp cam in the future, but for now I just want to focus on this exhaust install.

Also, one more question: Will I need to do any tuning once I put this system on? I want to make sure I reap all the benefits I can.

sofakingdom

iTrader: (1)

You won't gain much at all. 20 HP is probably not too far off the mark.

What you WILL gain however, is the potential for ADDITIONAL mods to add power. That's kind of how that part works... doesn't do a lot by itself, but without it, nothing else can do anything at all.

So don't let that stop you.

You can always do some tuning. First thing to do would be to advance the timing ahead of the stock "spec". You will find that it needs more fuel with a better flowing exhaust; I'd suggest running the idle air bleed in about ½ turn, and adding about 1/8 turn of tension to the sec air valve spring.

Rainmaster

Ok so what I'm really doing here is enabling my future mods to work their magic, correct? I think my ultimate goal is to drop an LT1 in, but if that were to happen it would be a couple years down the road. For now my goal is to get this LG4 up to at least 250hp which will be all I need to ensure I don't lose to today's 4 cylinder cars.

Confuzed1

iTrader: (4)

Yes, advancing the timing a little along with the better breathing exhaust will help with the power issue. 250hp is a lofty goal though for a 150 hp LG4.....I doubt I got that with my L69 with headers...and it started with 195hp in theory....but it seemed to pull really well.

Today's 4 bangers are so advanced.....my wife's 2013 Kia Optima cranks out 274HP with a tiny turbo.....get that LT1.......

Nothing wrong with the LG4.....just don't consider it any kind of performance engine compared to today's standards. Just too many advances have occurred between then and now.

Rainmaster

I'd at least like to make 200+ hp out of this LG4. 150hp from a V8 is laughable compared to stuff today. Heck even my '92 Jeep Wrangler makes 130hp with a 4 banger, and that's only a few years newer than my Trans Am. I guess what matters in the end is the Torque because that's what is going to help me win light to light. I almost certainly will upgrade to an LT1 in the future. I'll probably save it as a project to undergo in a few years time. As for now, I'd like to do as much as I can that will both give my LG4 some respectable muscle as well as provide a nice place for an LT1 to be swapped in later on.

chazman

iTrader: (4)

I'd say exhaust and L69 air cleaner are your biggest bang for your buck on a stock LG4. As has been mentioned, maybe bump up the timing a few degrees as well. Even going with 2.25" exhaust manifolds from an L69/LB9/L98 would make a difference with a 3" exhaust, if you didn't want to go with headers.

A 20 or so horsepower bump is a fair expectation here. It doesn't sound like much, but it will change the personality of your car.

Damon

The swap from the LG4 "pea-shooter" 2-1/4" exhaust and lo-po manifolds to a set of shortie headers and full 3" exhaust will make a noticable improvement. I agree, 20HP is definitely doable. (If your existing/factory cat is clogged up it could be 100HP, though!!)

Bump the timing. ~6* initial as opposed to the factory 0* setting seems to be about optimal on the LG4s I've played around with, but feel free to experiment up or down from there. Remember the 85 has a knock sensor, so more doesn't always equal better. It could be pulling the timing back if it hears detonation and that kills performance if it kicks in. And remember to use the factory timing procedure when you set the base timing (not difficult, but very important).

Also, get a set of DR secondary rods to put in that QJet carb. DR rods work MUCH better than the factory CH rods that came in all LG4 carbs. (DR rods are the same ones that were put in the factory L69 305 HO carb and they work just as well on an LG4). They're easily swapped out from outside the carb- no need to take the thing apart and dig around inside it.

L69 air cleaner or just a cheap open element air cleaner will breathe a lot better than the factory LG4 single-snorkel (plus sound cooler).

And don't forget the simple stuff- like a fresh cap, rotor, plugs and wires. You'd be amazed the difference vs. old worn out stuff.

None of this is going to get you 250HP, but the difference in torque and throttle response will make it feel like a LOT more grunt than just the peak HP improvement would suggest.

Confuzed1

iTrader: (4)

Good point Damon! I seem to recall changing my secondary rods and hangers on my L69 when my original carb crapped all over itself.

I ended up getting a remanufactured one…most likely an LG4 carb. I wished I would of swapped those rods/hangers out when I traded mine in to get the core charge back…. I used DR rods and "B" hangers on the secondaries. Woke it back up along with lightening the secondary spring a tad. No hesitation whatsoever. I had also installed a Crane 2040 Comp-U-Cam…played nice with the CCC system. I still have the engine sitting rebuilt on an engine stand. Ran great for what it was when I pulled it.

But the exhaust is the best place to start with the LG4's…or any 305 really IMO. I ran Edelcrock TES shorties into a Hooker 3" cat-back. And yes, the TES headers aren't the greatest for 350's and up, but an improvement for a 305…

Tuned properly with the above, and you should get over 200HP I would think.

JamesC

iTrader: (5)

I started with an LG4. I stuck on a L69 dual snorkel/ducts, did some carb tuning, threw in another cam and intake as well as a full L69 exhaust (manifolds, y- and intermediate pipe and a high-flow cat). I'd guess that in the end the motor was the equivalent of the L69 or very close. The mods made a difference in the fun factor of driving the car and I don't regret doing them. That said, I eventually swapped in a GM 350 HO Deluxe and the fun factor exploded.

On a side note, IIRC, my after market LG4 intermediate pipe (2.5") wasn't as large as the OE L69 pipe (2.75). Below is a comparison of the LG4 and L69 Y-pipe.

JamesC

chazman

iTrader: (4)

My '83 Crossfire had the same exhaust as the the LG4. I've replaced the 2" LG4/LU5 exhaust manifolds with L69 2.25" manifolds, 3" exhaust and SLP 2OTL, and it made a big enough difference to be worth it.

Confuzed1

iTrader: (4)

The original L69 exhaust is a good option, but I'm not sure it's easy to find with the 4 bolt flanges…maybe it is…

I also threw a different intake on too, a Weiand Action Plus…allowed me to use the Q-jet and air cleaner. IMO though, that should be one of the last mods since the stock intake isn't a big restriction…that exhaust you have is..

c4mo

iTrader: (3)

Do you have any pull a part junkyards around you? Or Craigslist
I ask because, if you could find a 96-98 vortec 350 or 96-02 in vans. You would have more power and it wouldn't cost much more. Even with stock l98 manifolds or 50 dollar used shorties I see all the time on the classifieds, it would be a great improvement. Used vortec carb intakes are cheap and most dual planes are dual pattern to keep the qjet.
I've purchased a few of these engines complete long blocks for 100-200. Just a thought.

Rainmaster

I believe there are a few yards around that I could take a look at. I think what I would like to do is just get either an L98 or an LT1 long block and then bolt up my carb and exhaust setup to it.

rusty vango

sorry to tell you this but even a stock Honda civic will hand you your ***. LG4s are usually around 110 hp by the time we get them so...think about what you want here. a full on drag car. OR a nice daily driver.kinda hard to combine the two without bucket loads of $100s

Damon

Aw, come on, Rusty, you're being a little hard on the LG4. I know they're usually in LOUSY shape if you went out and bought one used today, but the motor itself is not a total slug, it's just a slug given it's got 305ci of displacement.

LOTS of stuff goes wrong with them over the years which can sap a LOT of power from them, even vs. their stock rating. My personal favorites are plugged up cat converters, stuck-shut exhaust EFE valve at the exit of the pass. side manifold, choke not opening fully preventing the secondaries from opening, and general monkey-mechanic work done to the carb and/or setting of the ignition timing. That's how you turn a lackluster 150HP engine into a pathetic pig 100HP engine!

The 1985-up variant on the LG4 was noticably better than the 84-down motors mostly because it got the higher 9.5:1 compression ratio of the L69 in those years (previously it was rated 8.5:1, but even lower in reality if you took the time to measure and cc everything). Basically it was the same as the L69 except for the "peanut cam", horrible exhaust and the chip they put in the ECM with a LAZY timing advance curve. Address those things and you can easily make it MORE POWERFUL than a same-year L69. 250HP is, admittedly, out of reach without a cam change. But equaling the L69 with a good exhaust system and optimizing the carb and ignition timing is a realistic goal, I think. Plus PILES more torque than stock throughout the low-mid RPM range.

As for mopping up a modern Civic.... well, OK, can we discuss the importance of the driver in this equation? Most Civic drivers would never race, let alone know how to.

Rainmaster

I'm not expecting to get 250hp with just the dual snorkel and exhaust alone. But is it really that far fetched to get that kind of power rating with these mods in conjunction with a mild cam, better chip, better intake manifold, better timing advance, and a good tune up? I guess as long as I can put r*cers with their weed-whacker exhaust in their place I'll be happy.

Damon

If you're going to do a cam change, you might as well think about stepping up to a larger motor, is my feeling. External stuff is easily swapped onto a bigger/better motor. Internal engine part changes... not so much.

Still, if you wanted to do a cam swap in that engine the base model Edelbrock Performer cam (also sold as the Summit house-brand K1102 cam for $90 including new lifters) works beautiful in those mid-80s 305s. It works with the ECM and all the smog stuff, idles smooth, passes smog check in most places and will generally get add a pile of power vs. the stock LG4 cam. You don't even need to change valve springs if you keep the RPMs under 5500. It's about .050" more lift and more importantly about 15* more duration than the stock cam, but still very very mild as performance cams go.

Do all that and yeah, you might stand half a shot at tickling the 250HP range with a sharp tune. For sure, you won't need a dyno to know it's belting out a lot more power than it was before.

c4mo

iTrader: (3)

Its not outlandish thinking at all. With everything in good working order you would probably make 270-290 depending. I had a 86 montecarlo ss with original l69, performer intake, mechinical hei with modified 79 model qjet. With long tube headers and true dual exhaust and 3.73s out back. The car went on long trips, started up every single time and accelerated well. It was a perfect daily driver IMO. Was it fast, no, but it ran well enough to feel good. To be fair though, almost any modern v6 car would have ran it down.
Do the exhaust as you've expressed interest in and keep your vision towards a engine swap. This stuff keep getting cheaper (used) as the lsx family keeps up its natural progression.

aaron7

iTrader: (7)

But seriously, if you're going as far as camming... just pull a few more bolts and drop a 350 in there

In order to hit 200hp you'd need heads, cam, intake, exhaust, and a good tune. Scour the swap meets, forums, and craigslist for parts if you're dead set on that anchor!

Hey, could have a V6 lol

Fast355

iTrader: (2)

You are seriously under estimating a 305.

I had a stock 305, bored .040" over with flat top pistons, used the TPI 081 heads (also used on later model LG4s and L69s and practically identical to the 416s), used a stock 350 camshaft, 1.6:1 full roller rockers, and a stock 350 TBI intake manifold and throttle body. A set of headers and a 2.5 to 3" single exhaust. Backed to a 700r4 with a S10 converter and 3.08 gears it ran great in my heavy G20 Van. Put down 181 RWHP/268 RWTQ on a Mustang Dyno untuned with the 350 chip. Tuned the power climbed to nearly 200 RWHP/280 RWTQ with a locked converter. (75 mph forced lock)

More recently I put a 305 in a 1984 Elcamino that needed an engine. Car was in good shape, drivetrain was shot. We put a $400 LB9 305 from a 1985 TransAm in it. Bought it with a complete TPI unit on top and robbed it for a future project (making the engine essentially a $100 engine). The 305 had been rebuilt to stock and overall very fresh. Leakdown in every cylinder was within a few % and cranking compression was 180 psi across the board. We pulled the TPI off, slapped on an edelbrock performer intake with EGR. The previous owner had butchered the CCC Q-Jet wiring, so I eliminated it and. I used a non computer electric choke Q-Jet from an early 80s 305/350 van and and started with an older HEI distributor recurved to L82 corvette specs. I eliminated the air pump and left only the EGR valve and TVS units for the aircleaner, timing advance, and EGR. I hated the over the spark plug exhaust manifolds and tiny Y-pipe in the car, so we replaced the manifolds with ones from an early 90s G-van. They are a 2 1/4" outlet version of the manifolds you would find in many 70s cars and trucks. We ran 2.5" pipes into a dual in/single 3" out catalytic converter and a single 3" exhaust into an 18" case magnaflow muffler and a 3" tail pipe. The engine ran so well it wasted the TH200C within a few miles requiring us to find a TH350 to put in its place. With the stock converter and 2.43 gears that Elcamino still runs very respectably. We put it on the dyno to dial in the carb (was lean on the primaries/rich on the secondaries and rich at cruise when stock) and timing advance (13* initial, 35* total @ 2,600, 10* @ 10 in/hg manifold vacuum) and layed down close to 200 RWHP and 270 RWTQ. On long highway trips even without the lockup the elcamino is pulling down 24-26 mpg.

Confuzed1

iTrader: (4)

Agreed…My L69 with the 416 casting heads (came with it) -All rebuilt .030 over, KB hypers, CCC Q-Jet carb, Crane 2040 Comp-u-cam, TES shorty headers and a Hooker cat back…it ran great! It was a pretty stout engine, and the stock 3.73:1 peg-legger rear helped too.

I never checked the milage since honestly, if I were concerned about that I'd buy a Honda Civic…not a Thirdgen..(unless it had a Iron Duke )…

I'd venture to say it would give stock 350's a good run for their money….till I got my *ss handed to me by a kid in a older (2002 or so) Cadillac STS with a 32V Norstar engine..all stock. I kept up with him 0-60…right beside him. But his car kept pulling on me, and I had mine floored. I was not happy to say the least, after all the work I'd done on my little 305.

That's your reality check nowadays….decide now….305 or 350 (or 383)…or LSX

Fireblood83

Any progress?

Rainmaster

Yes actually, I got the whole system on back in April. I can definitely feel a difference in power in addition to the obvious upgrade in sound. This thing sounds like a monster now! It's hard to believe that it comes from an LG4. I now have the loudest car in my school's parking lot. In fact, the other day a kid was revving his car (a 90s Acura of some sort, Idk) so I decided to respond with a mighty roar. I think the kid nearly **** himself, it was awesome!

Overall, I am extremely satisfied with this Hooker, Magnaflow, and GMMG setup. Now I just need to give my car more of a bite to go with the bark, which I think I'll do by upgrading the cam and ignition system. So far, so good though. Hopefully I'll be able to reach the 250-300 hp mark one of these days.

Fireblood83

brilliant, just brilliant. If you manage to take some pics or maybe a video, that would be great.

Rainmaster

I finally got around to putting a video together. I don't think it does the system justice because it sounds so much better in person, but it's the best I can do. Hope you guys enjoy!

https://www.youtube.com/watch?v=Fc6x...ature=youtu.be

dmccain

iTrader: (2)

I had an LG4 firebird formula back in the late 90s. I swapped out the intake and carb, i believe an edelbrock intake and a 650 holley double pumper. MSD ignition, Headers, 3in exhaust, 3.73 gears, and a cheap summit cam i think maybe 450 lift. It ran high 14s so i would say it had 225hp+ or -. Not bad but really no faster than the Lb9 TPI 92 z28 i bought later on.

Fireblood83

Thanks for the upload. Man it sounds mean! Of course it's not like in person but still a big night and day difference from what your car previously had.

Confuzed1

iTrader: (4)

Sounds GREAT!

Rainmaster

Thanks for the comments guys! I think that this system is money well invested. Not only do I get the performance gains and a muscular sounding car, but since all of the pipes are either stainless or ceramic coated, it's sure to a lifetime.

Rainmaster

Oh, one more thing...
Could someone move this thread to the exhaust section of the forum? I don't think it's very much about my engine performance anymore. Thanks!

83ZZZ28

CONGRATS .... Sounds Awesome ! !

Rod

83ZZZ28