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Old 01-08-2002, 06:13 AM   #1
LegendNH
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Default How much hp does the L88 really have?

I know it's rated at 435hp but I have heard many people tell me it's closer to 600hp. This was one of the baddest corvettes every porduced. It struck fear into anyone challenging this beast. So is it true did it really have closer to 600hp


Also one other thing, why is the 427 more popular then the 454. I know the 454 was the largest engine but when i ask people this question they think it's 427. So why is the 427 more famous then the 454? Thanks in advance
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Old 01-08-2002, 06:19 AM   #2
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Default Re: How much hp does the L88 really have? (LegendNH)

Rumors in this time were about 550 HP with headers......... :D :D :D
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Old 01-08-2002, 06:21 AM   #3
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Default Re: How much hp does the L88 really have? (LegendNH)

Having both engines I say the 427 revīs easier, but the 454 delivers boatloads of torque.......:D
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Old 01-08-2002, 11:11 AM   #4
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Default Re: How much hp does the L88 really have? (454Big)

Corvette Fever, January 1993:

Click the image to open in full size.
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Old 01-08-2002, 11:19 AM   #5
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Default Re: How much hp does the L88 really have? (LegendNH)

LegendNH,

The L-88 was factory-rated at 430hp.....not 435hp. The L-71 and the L-71/L-89 were rated at 435hp.

The L-88 and the ZL-1 were classic examples of engines designed for racing, but delivered with necessary restrictions due to government regulation. One of those most-obvious restrictions were the factory exhaust manifolds. Installing headers on a L-88 or ZL-1 was like turning an 18 year-old virgin loose in a room full of drunken Marines....in other words, all hell broke loose.

Chevrolet was so serious about these engines that side-mount headers actually received a Chevy part number. They were built by a company called Kustom Headers. How do I know? I bought a set way back in 1969. You'd be amazed what they do for a L-71 as well!



[Modified by 67HEAVEN, 4:24 PM 1/8/2002]
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Old 01-08-2002, 11:19 AM   #6
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Default Re: How much hp does the L88 really have? (SuperFast80)

I read 560 somewhere.......................
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Old 01-08-2002, 11:30 AM   #7
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Default Re: How much hp does the L88 really have? (LegendNH)

More -- much more -- than the figures published by GM. :)
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Old 01-08-2002, 11:39 AM   #8
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Default Re: How much hp does the L88 really have? (LegendNH)

Based on what I've seen and read I'd say 520 with manifolds and 560 with headers. You really see a major difference with headers on a motor that moves such cfm.

I don't doubt one could tune a stock L88 with headers to 580 - 600 HP range. Pure stock would be limited to under 540 HP. Either way, it's pretty awesome.
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Old 01-08-2002, 12:00 PM   #9
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Default Re: How much hp does the L88 really have? (LegendNH)

These are fairly close ratings...David Vizard and Smokey Yunick have done dyno pulls where carb tweaking, ignition tuning (albeit was electronic) and open exhaust yielded easily over 600 hp.
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Old 01-08-2002, 01:12 PM   #10
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Default Re: How much hp does the L88 really have? (LegendNH)

If the balance of my parts ever get here from different restoration shops around the country :rolleyes: , I plan on having my motor dynoed when it is together. Hopefully by mid-February.

It is going together as a late '69, with the open chamber heads and the 4296 double pumper. It is bored .030 over. The only decision I have not made yet is whether I am going with the stock exhaust manifolds (which if I do would have the smog pump connected) or some sort of header set up.

I will be sure to post the results on the forum.
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Old 01-08-2002, 01:20 PM   #11
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Default Re: How much hp does the L88 really have? (67HEAVEN)

The 430 rating was chosen so that it would be lower than 435 to keep the unknowing from ordering it. Chevy expected the buyer would install headers as soon as he got it home & offered headers. Chevy did not want to install headers on the assembly line & put headers in the trunks of some early Z28s- is that a hint or what. :cool:
The 427 was designed as a race engine. Many prefer the 454 & esp. a Chevelle guy might prefer a 454 - 1970 SS.

You might want to see my website for How the Corvette got the BB.
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Old 01-08-2002, 01:35 PM   #12
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Default Re: How much hp does the L88 really have? (Ganey)

According to some the 430 HP was accurate. If you look at the Chevy numbers they say 430 HP @5400 RPM, this is not where peak horse power is made. So, they could always defemd themselves as being honest although misleading.
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Old 01-08-2002, 01:45 PM   #13
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Default Re: How much hp does the L88 really have? (LegendNH)

Quote:
So why is the 427 more famous then the 454?
The answer to this question is, L88.

A little bit of the mystique of that engine rubs off on every "427", even the passenger car version that resides in my 68. :) MJ
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Old 01-08-2002, 02:16 PM   #14
Chuck Harmon
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Default Re: How much hp does the L88 really have? (BAD-L88)

Quote:
________________________________________ ______________________
According to some the 430 HP was accurate. If you look at the Chevy numbers they say 430 HP @5400 RPM, this is not where peak horse power is made. So, they could always defemd themselves as being honest although misleading.
________________________________________ ______________________

Bad-L88,

You are quite correct, but I think the rated rpm was only 5200. Horsepower actually peaked closer to 6800 rpm. The 425 hp rating for the Hemi was also done at a low ~5000 rpm.

My reason for my going with the L88 instead of the 454 was that a shorter stroke engine is typically easier and safer to rev high than a longer stroke motor. I wanted the personality of a high revving small block with the torque of a big block. The L88 truly fits that bill. The greater torque of a 454, i.e. LS7 which is a 454 L88, was more than I thought I could use. The tires really can't hold the L88 under 100 mph anyway, so why add even more torque? You see, I am a very practical guy!

Chuck
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Old 01-08-2002, 09:53 PM   #15
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Default Re: How much hp does the L88 really have? (Chuck Harmon)

Bad L88, If you are going the show car route with your L88 then the exhaust manifolds are a must. If the car is going to be driven then headers are a must, you will see a huge HP difference with the headers!
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Old 01-08-2002, 11:13 PM   #16
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Default Re: How much hp does the L88 really have? (SBR)

I am really torn, I might do both. One thing for Monterey, another thing for everything else. I generally like to keep things on the stock side but it is so hard to resist putting headers on it. It is not the end of the world to change them back. Hopefully if I go with the headers we can dyno it both ways.

Then I was thinking the stock manifolds to the chambered exhaust. Does that do anything for me? This exhaust thing has a life of it's own.

I need to make some decisions soon. My crankshaft, connecting rods, and pistons got here Monday. I mean they were supposed to get here Monday, they are still not here. :mad
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Old 01-08-2002, 11:22 PM   #17
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Default Re: How much hp does the L88 really have? (BAD-L88)

Quote:
...
Then I was thinking the stock manifolds to the chambered exhaust. Does that do anything for me? This exhaust thing has a life of it's own.
...
The chambered exhaust is too restrictive. W/ headers the stock ex. is pretty much ideal w/ a straight shot out w/ the mufflers at the end. The curves under the rear end are not so bad being near the end.

:cheers:
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Old 01-09-2002, 01:03 AM   #18
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Default Re: How much hp does the L88 really have? (Chuck Harmon)

Chuck,

What camshaft and specs are you running in your L-88 427?

I just checked out your website and was impressed with your shifting!!! Sweet!!!!:cool:

I also have a Richmond Six and a 3.08 rear. Do you think that I will be able to lose traction with my 454 buildup at 3000 or so rpm's like you do??? I am running 245/60 R15's back there.

Bob :cheers:
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Old 01-09-2002, 02:50 AM   #19
Chuck Harmon
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Default Re: How much hp does the L88 really have? (Bob Turner)

Bob,

I'm running the factory L88 cam. Once considered radical, now considered to be a pretty low lift cam, (.54in, .56ex). Duration is long, however. You have the same 1-5 overall gearing I do. The only difference is that mine has the .82 overdrive.

The cam really does come on at about 3000 rpm. Although I have never driven or ridden in a nitrous car, I think the feeling must be similar when the L88 hits its rev band!

Thanks for the kind comments on my shifts, but I really need to make a new and better recording. I also need to get stickier tires! The ones on there now are 235/60 15's TA's. They hook up about as well as bare steel rims. I will probably be going with 8x17 Halibrand Sprint II wheels, and 255/45 KDW tires. This will give me approximately 26" diameter and 8.5" tread width. I might go with 235/17's in front.

Chuck

p.s. With the cam and compression you will be running you will be giving up a little bit; but, with the extra cubes you will be getting the majority back in the form of torque. I believe you will be having some serious tire wear problems!





[Modified by Chuck Harmon, 10:44 PM 1/8/2002]
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Old 01-09-2002, 04:09 PM   #20
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Default Re: How much hp does the L88 really have? (Chuck Harmon)

Chuck,

Wow, I just checked the stock L-88 cam duration specs- 262/273 at .050!! That thing must be a monster. The compression ratio (12 to one) is what scares me the most!! :eek:
Do you run racing fuel (100+ octane) in it? I would be afraid to run over 10 to one on the street with pump gas!!

How is the Richmond holding up?? I was afraid that I would harm it with BB torque but I can see from other forum members that it is stronger than I thought. The real test will be with Merlin522's BB!!

I have NEVER driven a car with a BB in it (nevermind a Corvette), so it will be a thrill for sure the first time taking it out for a spin.

Bob
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Old 01-09-2002, 04:09 PM
 
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