L48 low-cost performance
Thread Starter
Racer
Joined: Nov 2004
Posts: 319
Likes: 0
From: Sunnyvale CA
L48 low-cost performance
Ok so I, through much deliberation and toil, have decided that I want to work on performance rather than getting new paint. So here's the situation:
-I live in Cali (gotta pass smog)
-I'm a high school student (I wanna spend $500-$600 on performance for now)
-Because of gas prices, I want to make the fuel economy better rather than worse if I can help it
-I have an L48
I was thinking about having a friend of mine help me stroke it to a 383, maybe get new heads... but I really don't know much about engines yet. Can I get some advice for low-cost performance?
-I live in Cali (gotta pass smog)
-I'm a high school student (I wanna spend $500-$600 on performance for now)
-Because of gas prices, I want to make the fuel economy better rather than worse if I can help it
-I have an L48
I was thinking about having a friend of mine help me stroke it to a 383, maybe get new heads... but I really don't know much about engines yet. Can I get some advice for low-cost performance?
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Originally Posted by Empatho
I say get some vortec heads they are not expensive
Empatho, you are correct, but then he will need an intake manifold....$600
just ain't enough to finish the job...but that is what I would do. It raises compression, better flowing heads. Add a mild camshaft, it will keep the fuel economy and pass smog test...
Burning Brakes
Joined: Jul 2000
Posts: 1,162
Likes: 2
From: Beaverton, OR
Mike, it doesn't sound like you have the money to stroke it. You have enough money to maybe pick up a set of heads, but maybe not even that. Have to remember that head gaskets aren't cheap either. I'd suggest you start looking at www.summitracing.com for what things cost. They actually have some pretty nice heads over there under their own brand, I think they are around $300 per head and people around here seem to think they're good for the money. Don't recall for sure which heads they were, you'd want to check the archives. . .
If you really want to stick to $500-600, I'd say maybe a cam swap. Also, recurve your distributor, it'll cost you less than $10 and can make a pretty good difference. Just remember where it started, I don't know if you'll still smog, I don't have those things to worry about with my '74. . .
If you really want to stick to $500-600, I'd say maybe a cam swap. Also, recurve your distributor, it'll cost you less than $10 and can make a pretty good difference. Just remember where it started, I don't know if you'll still smog, I don't have those things to worry about with my '74. . .
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
The most bang for the buck is headers with a good free flowing exhaust and a street port job. These two together are worth about 40 to 50 HP. You can do all this yourself.
BigBlockk
Later.....
BigBlockk
Later.....
Thread Starter
Racer
Joined: Nov 2004
Posts: 319
Likes: 0
From: Sunnyvale CA
Ok so I was looking at summit racing's website, and for a pair of vortec heads it would be about $660, and for the vortec intake manifold it would be about $170. how much more hp would I see coming from this? and what kind of cam should i look for?
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Thread Starter
Racer
Joined: Nov 2004
Posts: 319
Likes: 0
From: Sunnyvale CA
I am just putting this out there, but what about dual carbs? How hard is that to do and what benifits are there?
The reason why I had mentioned stroking it was because I really want the low end torque where it counts, and I have a friend who knows a guy who will bore, stroke, and rebuild the engine for $1000.... then maybe just throw on vortec heads and intake.....
The reason why I had mentioned stroking it was because I really want the low end torque where it counts, and I have a friend who knows a guy who will bore, stroke, and rebuild the engine for $1000.... then maybe just throw on vortec heads and intake.....
Last edited by 76mike; Aug 17, 2005 at 04:58 AM.
Racer
Joined: Dec 2003
Posts: 304
Likes: 0
From: Pasadena Maryland
I woke up my L48 with a complete package from Pace Performance. For $795 I got the complete Vortec Head package. They give you a choice intake manifolds if you have to smog. I added a GM L-82 cam for $89.00. Added a Street Avenger 670 CFM Holley and Jet Coated Headers. You will have to keep the Cat but here in Maryland if you got Historic Tags you're exempt so I went with true dual Flowmasters with no Cat. I not only probably doubled my HP but I'm actually getting better gas mileage to boot. Cost me about $1500 for everything.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Originally Posted by 76mike
I am just putting this out there, but what about dual carbs? How hard is that to do and what benifits are there?
The reason why I had mentioned stroking it was because I really want the low end torque where it counts, and I have a friend who knows a guy who will bore, stroke, and rebuild the engine for $1000.... then maybe just throw on vortec heads and intake.....
The reason why I had mentioned stroking it was because I really want the low end torque where it counts, and I have a friend who knows a guy who will bore, stroke, and rebuild the engine for $1000.... then maybe just throw on vortec heads and intake.....
The same, however, can not be said for the exhaust side. Headers and a good 2.5" exhaust will always be the biggest bang for the buck as far as bolt-on modifications. A good flowing set of heads will further improve upon headers. Careful cam selection would realize the full benefit of the headers and heads. At the other end of the drivetrain, a steeper set of gears if you can live with the increase in cruise rpm. Going from a 3.08 to a 3.55 really changes the character of the car.
Of course, all of this has to fit your scheme. Some of us, me included, do not want to use headers for our own personal reasons so you have to follow a different path. But it would never start with the intake and carb replacement unless you were dealing with a problem, like a really bad Quadrajet, that you've decided to solve with a carb/intake replacement.
But the very first place to start and greatest return on investment is a good tune up including a recurved distributor and optimized carburetor.
Racer
Joined: Jan 2003
Posts: 383
Likes: 0
From: Columbia SC
76mike
I am not sure about your state but I was told that if I change my 76's 2-1-2 configuration in any way it would not pass inspection. Now that was in New Jersey.
I moved to South Carolina and we dont have any vehicle inspection so naturally I changed the whole setup...
Suggest you find out how much you can change your exhaust and still pass inspection. You will want headers and true duals, free flowing cats and whatever muffler you like. I hope you can change your configuration cause the exhaust system upgrade will be a big help to you along with the heads, cam and stoking.
Also the suggestion to get what in NJ is called QQ plates (historic or antique) is a good idea especially if it exempts you from going through the inspection line. Check this out first and then design your Vette around what you can get away with.
I am not sure about your state but I was told that if I change my 76's 2-1-2 configuration in any way it would not pass inspection. Now that was in New Jersey.
I moved to South Carolina and we dont have any vehicle inspection so naturally I changed the whole setup...
Suggest you find out how much you can change your exhaust and still pass inspection. You will want headers and true duals, free flowing cats and whatever muffler you like. I hope you can change your configuration cause the exhaust system upgrade will be a big help to you along with the heads, cam and stoking.
Also the suggestion to get what in NJ is called QQ plates (historic or antique) is a good idea especially if it exempts you from going through the inspection line. Check this out first and then design your Vette around what you can get away with.
Drifting
Joined: Sep 2004
Posts: 1,532
Likes: 4
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
Originally Posted by BigBlockk
The most bang for the buck is headers with a good free flowing exhaust and a street port job. These two together are worth about 40 to 50 HP. You can do all this yourself.
BigBlockk
Later.....
BigBlockk
Later.....
Melting Slicks
Joined: Jul 2000
Posts: 2,848
Likes: 0
From: Beacon NY
I have an L-48 and I'm just starting my rebuild (I hopefully will have the engine out of my car this weekend).
I plan on getting one of the Trickflow cam/cylinder head packages I found at summit. Below is a link from their catalog:
http://www.summitracing.com/catalogs...yaug/135f.html
Just be sure to read the fine print about how they tested the engine to get the horsepower they advertise. Some of them were tested on a 350 and the others were tested on a 383. The only thing is the kits recomend you use a 9.5-10.1 compression ratio (which is going to require a new set of pistons and, in my case, a complete rebuild).
I might be wrong, as I dont' know that much about engines, but I don't think that replacing your carberator will give you that much of a noticable horsepower difference unless you were having carb issues before. If I were on a budget, I'd go with a cam and an intake manifold.
I bought my car and it already had a Performer RPM manifold and cam installed on the L-48.
I plan on getting one of the Trickflow cam/cylinder head packages I found at summit. Below is a link from their catalog:
http://www.summitracing.com/catalogs...yaug/135f.html
Just be sure to read the fine print about how they tested the engine to get the horsepower they advertise. Some of them were tested on a 350 and the others were tested on a 383. The only thing is the kits recomend you use a 9.5-10.1 compression ratio (which is going to require a new set of pistons and, in my case, a complete rebuild).
I might be wrong, as I dont' know that much about engines, but I don't think that replacing your carberator will give you that much of a noticable horsepower difference unless you were having carb issues before. If I were on a budget, I'd go with a cam and an intake manifold.
I bought my car and it already had a Performer RPM manifold and cam installed on the L-48.
Last edited by Victor; Aug 17, 2005 at 10:12 AM.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
There's no specific definition for a "street port job" other than it differs from a "full race port job," whatever that may mean to you.
But, in general, a street port job would be fewer operations than a race job. That could me nothing more than port matching. It might also include port matching beyond the port entry, perhaps an inch or so deep into the port. It could also include blending the bowls. It would not likely include things like the short-turn radius.
A full porting would be the complete port reshaping from the entry to the valve seat (and opposite on the exhaust).
Some of these operations can be performed by a relatively inexperienced person at home. Some others require a very high degree of expertise on a flow bench and that type of cylinder head.
So, if someone uses such an ambiguous term, get clarification on exactly what they mean.
But, in general, a street port job would be fewer operations than a race job. That could me nothing more than port matching. It might also include port matching beyond the port entry, perhaps an inch or so deep into the port. It could also include blending the bowls. It would not likely include things like the short-turn radius.
A full porting would be the complete port reshaping from the entry to the valve seat (and opposite on the exhaust).
Some of these operations can be performed by a relatively inexperienced person at home. Some others require a very high degree of expertise on a flow bench and that type of cylinder head.
So, if someone uses such an ambiguous term, get clarification on exactly what they mean.
Instructor
Joined: Apr 2005
Posts: 101
Likes: 0
From: webster ny
recurve the distributor....
Originally Posted by dath
If you really want to stick to $500-600, I'd say maybe a cam swap. Also, recurve your distributor, it'll cost you less than $10 and can make a pretty good difference. Just remember where it started, I don't know if you'll still smog, I don't have those things to worry about with my '74. . .
I was thinking of just trying out new springs and adjusting my timing that way. Thoughts?
Hef
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
My recommendation:
Ensure ALL vacuum systems are sealed and working properly. This may require replacement of some of your intake heat sensors that are notorious for leaking vacuum
Carb rebuild/re-jet (read Lars' paper on ported/unported vacuum advance connection).
Ignition tune-up and recurve with eye to smog compliance while improving performance
Headers, freer flowing smog legal cat converter and turbo mufflers
3-angle valve job and cylinder head refresh
K&N Air Filter
This will put you around $600-750. You will see the most improvement with a good recurve of your distributor and timing adjustments (without this, the rest of the improvments will not yield as much). The balance of the changes will help compliment with better/improved breathing.
Ensure ALL vacuum systems are sealed and working properly. This may require replacement of some of your intake heat sensors that are notorious for leaking vacuum
Carb rebuild/re-jet (read Lars' paper on ported/unported vacuum advance connection).
Ignition tune-up and recurve with eye to smog compliance while improving performance
Headers, freer flowing smog legal cat converter and turbo mufflers
3-angle valve job and cylinder head refresh
K&N Air Filter
This will put you around $600-750. You will see the most improvement with a good recurve of your distributor and timing adjustments (without this, the rest of the improvments will not yield as much). The balance of the changes will help compliment with better/improved breathing.
Thread Starter
Racer
Joined: Nov 2004
Posts: 319
Likes: 0
From: Sunnyvale CA
How much would recurving the distributer cost me? I know that there are vacuum leaks, I have increased performance already by plugging a few myself, and the system is still not hooked up to the headlights or wiper fluid. So he's kind of a lineup of what I'm thinking about right now:
-exhaust: headers, high-flow cat, high flow mufflers
-enigne: vortec heads and intake
-other: recurve the disstributer and fix vacuum
How would I recurve the distributer? I've already replaced the cap and rotor and such.....
-exhaust: headers, high-flow cat, high flow mufflers
-enigne: vortec heads and intake
-other: recurve the disstributer and fix vacuum
How would I recurve the distributer? I've already replaced the cap and rotor and such.....
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Most reputable tuner shops can perform a distributor recurve. Tell them what you want to achieve and they will lay down a base timing and advance curve to fit your needs. After I had rebuilt my engine and added such things as intake, rebuilt carb, heads, headers, exhaust, etc. I still didn't have the expected performance. Recurve released the hidden power.