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The Sweet Sound of an L81+

Joined
Apr 29, 2001
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2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Well folks,

Once you give me a camera, then the experimenting never ceases....:L

I took a video of my engine idling and revving-up.

For those of you who may wonder what the engine would sound like when the compression is bumped-up to 9.5:1 and matched to a CompCam XE268H, enjoy!!! :upthumbs


http://www.bolt.com/GerryLP1111/video/L81_Engine_After_overhaul/2924476


GerryLP:cool
 

Yoda

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4,885
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Amarillo, TX
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1981 UL5
:upthumbs Gerry yea... Sounds a whole lot better than the last time I heard Gail ;) :lou
And the engine is rock solid steady :eek impressive :dance


Bud
 
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Apr 29, 2001
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2,141
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Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Thanks Bud, Heaven!

I am very happy with the engine. Imagine, all the stock components (including smog pump and injection air) are connected and functioning.

Soon I'll be taking it to the Dyno. I'll be happy with 240 HpRW (at the rear wheels). I'll be ecstatic :W with 300 HPRW :bu

GerryLP:cool
 

bill81vette

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Troy,NY
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1981 dark blue metallic
sounds very sweet, Gerry,hope you get what you want with the dyno!!!!:upthumbs
 

Peer81

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May 21, 2003
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Netherlands
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'81 Black
Very nice sound Gerry! :upthumbs
Like Bud says the engine is rock solid to, idles very smooth!

Have you ever dyno'd your L81 before?

Groeten Peter.
 
Joined
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Messages
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Rio Rancho, NM
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1981 HD Suspension; ZN1 Option
...Have you ever dyno'd your L81 before?

Groeten Peter.

Peter,

The L81 has never been dyno'ed before. It was a $750 dollar expense that i thought would not be needed, since we're talking about a nearly stock engine.

I had the Vette on a chassis dyno before, but that was when my 1968 short block was in the car.

We're expecting another snow wave to arrive this afternoon, and the weekend is shot as far as the weather is concerned. Perhaps next week will be alright to take the Vette to the dyno.

GerryLP:cool
 

Peer81

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'81 Black
Gerry,

Are you telling me a dynorun is $750 dollar? Or is it for the hole afternoon?
I did mine 4.5 years ago with a all stock L81 and normal Dynomax mufflers. She did a 172.3HP and 351Nm (= 233lbs/ft). I'll hope you get your 240 or more :)

Groeten Peter.
 

hdkeno

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Joined
Mar 12, 2006
Messages
277
Location
CT
Corvette
2005 Victory Red coupe
Sounds great Gerry,

Plus you have the benefit of a almost "stock" engine, In keeping with the originality.

Did you do the the work youself,primarily a hotter cam?

Also how is the "seat of the pants" difference?

Now you have me thinking.....

Enjoy, and sit back with a nice cold one. Later,Ken
 
Joined
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Messages
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Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
hdkeno said:
Did you do the the work youself,primarily a hotter cam?

Also how is the "seat of the pants" difference?

I had the block and subparts prepared by a local quality (which mean$ mucha$ mula$) shop (Edward's Engines). I assembled the engine myself, and I used my proven XE268H cam. I used Performance Trends Inc. Compression Ratio Calculator to help me decide which piston to use. When you find yourself trying to make a decision on pistons, it is nice to have the number's to back-up your decision. I am still shy by about 150 miles from my break-in goal, so I really have not hammered hard the engine, but Gail surely likes the 2k - 3k rpm range in the freeway.

peer81 said:
Are you telling me a dynorun is $750 dollar? Or is it for the hole afternoon?

Peter, the 750 was for an engine dyno. The chassis dyno will cost me $85 for three pulls, but if tuning is needed, then my total will be no more than $300.

Yeah, 240 HPRW is not too much an impossible goal. I got my feel with my track engine, and believe me when I say, that a peak of 330, and then 345, and later 365 HPRW was not enough...once you get hooked with building power in your engine, then it is never enough, and this is a difficult habit to break, for you end-up not enjoying what you have in front of you (your beloved Vette).

Good old and wise Yoda master helped me understand that one day. It was a moment out of that famous story about a old bull and young bull.....just walk down and get them all done [he said]....;LOL

GerryLP:cool
 

Barry08

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Nov 16, 2001
Messages
89
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Portage La Prairie,Manitoba Ca
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1981 Victory Red
Gerry

Is that an auto or a 4-speed?
Have you still got the e4me carb and computer controlling everything?
Need the complete specs if you have the time?

Thanks.... Barry
 
Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Barry,

The Vette is an automatic transmission Vette. The tranny still has a 2,400 stall lock-up converter, but that was for the XE274 I previously had on a 1968 engine. The XE268 does work with the stock converter (http://www.compperformancegroupstor...C&Product_Code=12-242-2&Category_Code=12-CAM =) (EDIT: Changed link to the correct cam. The old link was for the big block version)

The E4ME Q-Jet still is hooked-up to the computer and it is running all the programmed functions (albeit when compared with todays automobile system computers, it is not a lot of functions :L ).

Smog equipment is also hooked-up and running.

The original L81 engine was disassembled, blue-printed, bored-over 0.020" to fit SP H618CP20 pistons with an advertised 0.125 dome that displaced 23.8 cc's @ 0.125 depth. The dome and the 0.015" head gasket allowed a change in the compression ratio (CR) from the advertised 8.2:1 to a 9.5:1 CR. I went with a chromolly-rings type hatch pattern in the cylinder bores. The replacement L81 heads chambers cc'ed at around 78 cc's.

View attachment 12517

The rotating and reciprocating components were balanced to within a few grams.

I will be taking the Vette on Monday (should weather permit) to the chassis dyno at Speed Dreams, Albuquerque, NM. These guy's are Vette heads.

GerryLP:cool
 

Barry08

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Joined
Nov 16, 2001
Messages
89
Location
Portage La Prairie,Manitoba Ca
Corvette
1981 Victory Red
Gerry,
I modified an 81 Camaro with the he268 made quite a difference but lost a little bottom end.You may want to keep that 2400 stall in there!Heard other guys keeping the e4me with some mods http://forums.corvetteforum.com/showthread.php?t=1428712
Take a look at that thread.I found with my Camaro that it still ran out of pull around 4000 to 4500 I believe it was due to the heads.Let us know what the dyno says? Thinking of doing what you did but stroking to a 383 at the same time.

Barry
 
Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Update! Update!

Well folks,

Dummy me here, didn't called ahead to make an appointment early enough (wow! who would have "thunk" it that the dyno is busy all week).

So they told me that they had a race car and an 07 Z06 dyno tuning today, and they could not accommodate me...:ugh ...:W :duh ...so I made an appointment for Saturday at 10 a.m.). I truly hope it won't be raining or snowing.

So hurry up and wait...

GerryLP:cool
 
Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
How much should it cost to do the CAM?

Thx

For the Cam kit, your looking at approximately $160.00, but this kit has lifters only. (http://store.summitracing.com/partdetail.asp?part=CCA-CL12-242-2&autoview=sku)

If you have to change everything (springs, keepers, lifters, timing chain, etc.) then it will about $310 dollars (http://store.summitracing.com/partdetail.asp?part=CCA-K12-242-2&autoview=sku).

Also, please understand that together with the use of this cam, I bumped the CR to 9.5:1 (versus 8.2 stock L81). One way you could do that is by changing to cylinder heads with a 64 cc chamber and going with a 0.021" gasket (a 0.015" gasket will give you a better quench. (this is based on my L81 block deck height of 9.030")).

If you keep the stock CR, then perhaps you should consider slightly less duration: http://www.compperformancegroupstor...CC&Product_Code=12-238-2&Category_Code=12-CAM

GerryLP:cool
 
Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Barry et al,

The dyno results show that I have a problem with the carburetor, so I have been waiting for obtaining all the needed tools for the calibration of the E4ME, so that I can at least provide you all with a true, No-BS, assessment of the performance.

Nevertheless, I have attached an image of the run. I have a video as well, but since it won't be the final dyno run, I'll wait until I get there before I post the video.

On the Dyno results, you'll see how the L81 reached a peak of 178 RWHP (HP @ the rear wheels) and 232 Lb/ft of torque at around 4,150 rpm. Also you'll noticed how the power and torque precipitously falls between 4,250 and 5,250 rpm. There lies the problem. I know that it could be a mountain of reasons or causes for this, and I am still in the middle of checking troubleshooting step #1. Take notice on the bottom fuel mixture chart how LEAN the engine is running. That's is why I am starting with the calibration of the E4ME procedure from the Rochester E4ME book (page 15).

These numbers are @ altitude of ~ 5,000 feet (Bar Press of 25.13 Hg In), and I have not gotten the dyno file, so that I can let the software convert it to sea level, but I suspect that it would show approximately 230 RWHP at sea level.

View attachment 12630
 

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