L48 engine???
Thread Starter
3rd Gear
Joined: Jun 2002
Posts: 3
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From: Houston Ohio
L48 engine???
In 1979 did these engines have much power to them or are considered "wimp engines." If so is there a common cure, such as a new set of headers and a less restrictive exhaust.
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
Re: L48 engine??? (corvetteless)
Headers, dual exhaust, and a good intake will bump the L-48 up to at least 240 hp.
With a good cam, you could easily expect 300 hp.
Don't go too far beefing up the L-48, the bottom end is not that strong. If you're looking for 350+ hp, it's probably better to build a new engine for the car.
-Steve
With a good cam, you could easily expect 300 hp.
Don't go too far beefing up the L-48, the bottom end is not that strong. If you're looking for 350+ hp, it's probably better to build a new engine for the car.
-Steve
Safety Car
Joined: Aug 2001
Posts: 3,685
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From: Waterford Mi
Re: L48 engine??? (Pacin'California)
Heasds, intake, cam, and exhuast will make it into a pretty nice street machine. Pistons are dished so you only have 8.5:1 comp. Flate tops pistons or 60cc heads should get it close to 10:1. Remember that the motor has to work with the trans and rear end gears to produce the best power.
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
Re: L48 engine??? (Pacin'California)
Don't go too far beefing up the L-48, the bottom end is not that strong. If you're looking for 350+ hp, it's probably better to build a new engine for the car.
-Steve
-Steve
The General says that two-bolt blocks will take 500hp all day.
I have personally spun my modded L48 -still has two-bolt mains + cast crank- to 7000rpm several (OK . . . more than several) times.
Thread Starter
3rd Gear
Joined: Jun 2002
Posts: 3
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From: Houston Ohio
Re: L48 engine??? (derv3tt3)
Houston, Ohio.......you see you blink and you miss it, but its about 200 miles north east of ya. Its between Piqua and Sidney if have ever heard of those towns. The town has a popualtion under 75.
Race Director
Joined: Feb 2000
Posts: 12,431
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From: CT
Re: L48 engine??? (corvetteless)
I have a wimp L-48 bottom end and have never had a problem. Just put on some cheap heads and a big cam and my car has come a long way. Last year i reved my L-48 to 6400 rpm all the time at the track and it never broke.
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Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
Re: L48 engine??? (45ACP)
Sorry, 45ACP. I guess I don't have as much faith in what was left of my block(left some of it on the freeway two years ago) than you guys do... ;)
I suppose you could run the thing up to 7k w/ 500 hp all ya want, I still would feel more comfortable with a stronger bottom end. Some of us may not be as lucky as you.
-Steve
I suppose you could run the thing up to 7k w/ 500 hp all ya want, I still would feel more comfortable with a stronger bottom end. Some of us may not be as lucky as you.
-Steve
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
Re: L48 engine??? (Pacin'California)
Sorry, 45ACP. I guess I don't have as much faith in what was left of my block(left some of it on the freeway two years ago) than you guys do... ;)
I suppose you could run the thing up to 7k w/ 500 hp all ya want, I still would feel more comfortable with a stronger bottom end. Some of us may not be as lucky as you.
-Steve
I suppose you could run the thing up to 7k w/ 500 hp all ya want, I still would feel more comfortable with a stronger bottom end. Some of us may not be as lucky as you.
-Steve
Yeah, I remember reading your post(s) when your motor coughed her cookies. If I remember correctly, wasn't it a problem with low oil pressure? I'm afraid no engine can stand up to that, even at idle.
Oh, and I did not mean to imply that I have 500 horses out front, I was just passing along what The General had to say. My best guess is that I have 400 or so.
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
Re: L48 engine??? (45ACP)
I was told by the mech it was low oil.
I'm really not to sure. It was either the #5 or #7 piston that blow and shot a pushrod out the side. Oil pressure was fine, oil'd been changed a month before. Maybe somehow, enough oil wasn't getting to that piston. Wish I took pictures at the time, one of the pistons was sitting at a 45 degree angle in the bore. Don't ask me how.
BTW, where'd you get the 500hp rating? The LM-1 and L98 blocks are both rated to 350 hp. The pistons in the engine can't be good for much, either.
You've got a good point about balancing the crank though. :)
-Steve(I only pretend to know anything about engines... so please don't take me too seriously!)
I'm really not to sure. It was either the #5 or #7 piston that blow and shot a pushrod out the side. Oil pressure was fine, oil'd been changed a month before. Maybe somehow, enough oil wasn't getting to that piston. Wish I took pictures at the time, one of the pistons was sitting at a 45 degree angle in the bore. Don't ask me how.
BTW, where'd you get the 500hp rating? The LM-1 and L98 blocks are both rated to 350 hp. The pistons in the engine can't be good for much, either.
You've got a good point about balancing the crank though. :)
-Steve(I only pretend to know anything about engines... so please don't take me too seriously!)
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
Re: L48 engine??? (Pacin'California)
I was told by the mech it was low oil.
I'm really not to sure. It was either the #5 or #7 piston that blow and shot a pushrod out the side. Oil pressure was fine, oil'd been changed a month before. Maybe somehow, enough oil wasn't getting to that piston. Wish I took pictures at the time, one of the pistons was sitting at a 45 degree angle in the bore. Don't ask me how.
BTW, where'd you get the 500hp rating? The LM-1 and L98 blocks are both rated to 350 hp. The pistons in the engine can't be good for much, either.
You've got a good point about balancing the crank though. :)
-Steve(I only pretend to know anything about engines... so please don't take me too seriously!)
I'm really not to sure. It was either the #5 or #7 piston that blow and shot a pushrod out the side. Oil pressure was fine, oil'd been changed a month before. Maybe somehow, enough oil wasn't getting to that piston. Wish I took pictures at the time, one of the pistons was sitting at a 45 degree angle in the bore. Don't ask me how.
BTW, where'd you get the 500hp rating? The LM-1 and L98 blocks are both rated to 350 hp. The pistons in the engine can't be good for much, either.
You've got a good point about balancing the crank though. :)
-Steve(I only pretend to know anything about engines... so please don't take me too seriously!)
Uhhh . . . just just woke up after a good night's sleep . . .
Ok, to clarify - The General (among many others) has said, when speaking of SBC with two-bolt mains, that they can handle 500hp. This is to say "modified" to 500hp, not a claim of that kind of output from of any of their production engines.
I just dug out my notes and so have them right here in front of me on the desk. Buried deep in the binder I see a photocopy that I did a few years ago. Unfortunately, I do not know the ultimate source, I do not see anywhere that I jotted down the name of the book. It reads, in part:
"In most cases, two-bolt main blocks are fine to use, especially if they have a high nickel content. The only reason you would choose a four-bolt block would be for resale or because you intend to use your engine for racing. I have never seen a broken main cap, and General Motors has reported that two-bolt blocks will hold up to 500hp, so a four-bolt block is not required for street use or even some drag strip use."
I can find more stuff like this, but I think I got my point across + I need caffeine right now and so have not the patience to continue.
/me departs to obtain caffeine.
[Modified by 45ACP, 5:03 AM 7/1/2002]
