Ouch Engine Damage

[yellow77]

Well, it seems when I am not around, my car has been involved in some unofficial street use of the nitrous. Anyway, this resulted in a very clean spark plug in the #7 cylinder and white smoke coming from the left tailpipe and constantly lowering water level.
So, this weekend, I removed the drivers side cylinder head and sure enough the #7 piston was very clean too. Can anyone say blown head gasket?
Anyway, it was then that I noticed the crown of the number one piston had a big exhaust valve shaped depression in it.
It looked like at some time in the past, the engine had been over revved and the valve had floated, hit the piston and broken off. The edges of the dent showed signs of multiple impacts and in total was over 1/8" deep. Oh my goodness, and I have thrown nitrous at this poor thing.
Well, I couldnt do much else, since it is my daily driver, so I reassembled the engine after replacing all the gaskets of course, and now she runs on all 8, a massive improvement, and doesnt smoke (steam?) any more.
Sooner or later I see a 383 in my crystal ball.

Cheers

Richard

 

[Pseudomind]

Your kids?

Your comment infers you may have known who might have performed the act.

Well, it seems when I am not around, my car has been involved in some unofficial street use of the nitrous.

 

[yellow77]

Your kids?

Your comment infers you may have known who might have performed the act.

Actually, my son owned up to it, he was keeping a diary online and let me read it, he is not solely responsible because I have run her at the track, says a lot for chevy engines that she has held up as well as she has.

Cheers

Richard

 

[bossvette]

I'm not a big fan of nitrous simply for that reason the temtation for more is always there. Cheap HP until you break something
When you put that 383 in sell the nitrous to help pay for it.

 

[yellow77]

Boss, when I get the 383, I wont need nitrous!! :L

 

[Evolution1980]

I would think you were asking for trouble right from the get go! Nitrous on an engine with aluminum cylinder heads running 10.0:1 compression?!?!?

I've been thinking about boosting my engine, but not until I change out the heads to lower my compression ratio ("CR")...
But I'd rather just scoot up to the ZZ383 specs, or a 396 makeover...then boost it! :L :L

 

[yellow77]

I would think you were asking for trouble right from the get go! Nitrous on an engine with aluminum cylinder heads running 10.5:1 compression?!?!?

I may be wrong, but my docs show 10:1 compression. I want the ZZ383, but really I would like Sallee Chevrolets 50 anniversary 383, it pushes 500HP!!!!!

Cheers

Richard

 

[Evolution1980]

I may be wrong, but my docs show 10:1 compression.

yep, my bad... I changed my post. It is 10:1. Still, from what I can recall, that's still high for any type of forced induction or nitrous... I seem to recall reading that for 'engine friendly' boost, the engine's CR shouldn't really be higher than 9:1 or so...

 

[yellow77]

Yep you got it, but I am (was) only asking for 100 HP extra, but after finding the damage on piston #1, I wont be doing that again for a while.



Richard

 

[Evolution1980]

Yep you got it, but I am (was) only asking for 100 HP extra, but after finding the damage on piston #1, I wont be doing that again for a while.

Only 100 HP extra... :eyerole That's a lot! :L

 

[Koop]

ZZ383 = 9:1...Nitrous friendly

Aluminum Heads, maybe not...

 

[Evolution1980]

ZZ383 = 9:1...Nitrous friendly
Aluminum Heads, maybe not...

The (old?) GMPP catalog states that the compression ratio is 9.1:1 which is wrong. The compression ratio is 9.7:1 for the ZZ383/425, using a .028" head gasket.
The compression ratio is 9.1:1 for the HT383 which uses a thicker (.051”) head gasket.

And the aluminum cylinder heads still are a bit worrisome when it comes to nitrous. I recall reading in one of the hotrod mags a few years back that the iron Vortec heads actually produced more power in some instances. I just can't recall the specifics.

 

[Koop]

The (old?) GMPP catalog states that the compression ratio is 9.1:1 which is wrong. The compression ratio is 9.7:1 for the ZZ383/425, using a .028" head gasket.
The compression ratio is 9.1:1 for the HT383 which uses a thicker (.051”) head gasket.

And the aluminum cylinder heads still are a bit worrisome when it comes to nitrous. I recall reading in one of the hotrod mags a few years back that the iron Vortec heads actually produced more power in some instances. I just can't recall the specifics.

My owners book says 9.1:1.

 

[yellow77]

OK Koop, how does she run with "MY" engine to be?

 

[SPANISHVETTS]

Here you go 500HP for under 6 grand.

 

[Evolution1980]

]Here you go 500HP for under 6 grand.
javascriptopUp('../specs/html/383_500lb.html')

try the link again... you are trying to link to a javascript page, which doesn't work.

 

[SPANISHVETTS]

try the link again... you are trying to link to a javascript page, which doesn't work.

Ok, the link is fixed.

 

[Koop]

ZZ383 Rocks!

OK Koop, how does she run with "MY" engine to be?

The HP is great and 460 pounds of torque is sweet! It turns 6,000 rpm so it really sings to me when she gets going. All of my Vacuum operated systems work properly with enough cam to sound real nice (tough balance in a '69 if you don't want to mod the vacuum system). It dropped in pretty smooth. I have to run a dual plane manifold so it's making a little less HP than advertised but it's plenty! It did need deep groove pullys and a high volume fuel pump, the stock ignition housing doesn't bolt up (yet) but that isn't a problem on a '77. I'm even running the stock quadrajet (re-jetted). No messing with a home cooked bunch of parts, factory backed, warranty and I couldn't have had this set up built for the price of the crate motor.

The biggest problem is getting it to hook up at launch!

The Vette will walk away from my CTS-V and a whole bunch of other cars. There's nothing like the look on the face of a guy in a 360 Modena that keeps checking his rear view mirror and then looks right at 140

 

[Evolution1980]

The HP is great and 460 pounds of torque is sweet! It turns 6,000 rpm so it really sings to me when she gets going. All of my Vacuum operated systems work properly with enough cam to sound real nice (tough balance in a '69 if you don't want to mod the vacuum system). It dropped in pretty smooth. I have to run a dual plane manifold so it's making a little less HP than advertised but it's plenty! It did need deep groove pullys and a high volume fuel pump, the stock ignition housing doesn't bolt up (yet) but that isn't a problem on a '77. I'm even running the stock quadrajet (re-jetted). No messing with a home cooked bunch of parts, factory backed, warranty and I couldn't have had this set up built for the price of the crate motor.

The biggest problem is getting it to hook up at launch!

The Vette will walk away from my CTS-V and a whole bunch of other cars. There's nothing like the look on the face of a guy in a 360 Modena that keeps checking his rear view mirror and then looks right at 140

Ahhhh...man...that warms me up just to read about it! Yeah, I was happy with my ZZ4, but....I NEED MO' !!!! (Isn't that always the case?!?!?)

 

[yellow77]

WOW, that sounds great Koop, even doing it on the nitrous, its nice to outrun the odd porsche 911 turbo out at the track, she runs mid 12's on the bottle, that would be nice normally aspirated. The ZZ4 is very stout and pulls like crazy from about 3000 to 5500 rpm. Nothing like a crate motor with a warranty.



Richard