Does this sound like a decent setup?
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Race Director
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Does this sound like a decent setup?
ZZ4 crate motor in whatever their "stock" configuration is, Weiand 142 blower, 700R trans, 2200 stall converter, Holley Avenger 670 carb. He said he tried a 750 but had issues with it bogging. Amount of boost unknown, there wasn't a boost gauge. Do you see any potential issues, anything inherently inappropriate about this combination? Test drove it today - fires right up, idles smooth. Really quick - dang. I see the ZZ4's in out of the box trim are considered on the low end of performance but it seemed pretty healthy.
He says the trans was recently rebuilt by a well-known local builder, from the performance I didn't see any reason to doubt it. Trans fluid looks pristine.
He says the trans was recently rebuilt by a well-known local builder, from the performance I didn't see any reason to doubt it. Trans fluid looks pristine.
Last edited by brassplyer; Feb 15, 2019 at 09:28 PM.
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He says the carb has whatever jets were in it, he changed the springs some. The motor is as it came. I have -0- experience with blowers but it seems to work.
Last edited by brassplyer; Feb 15, 2019 at 10:08 PM.
Le Mans Master
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From: Unreconstructed, South Carolina
IIRC
ZZ4 motors come stock with right at 10:1 CR using cast pistons … I have NO blower experience but I'm under the impression that Hi-comp, blown motors without computer management ...or without expert manual carb & ignition tuning … may be flirting with detonation
ZZ4 motors come stock with right at 10:1 CR using cast pistons … I have NO blower experience but I'm under the impression that Hi-comp, blown motors without computer management ...or without expert manual carb & ignition tuning … may be flirting with detonation
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Anyone else have info to impart on this topic?
Pro
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From: Texas
The 142 blower has 5 to 7 lbs boost.
DETONATION ELIMINATION The increase in engine output with a Weiand supercharger does have the potential of causing serious engine problems (in one area), detonation, knock, or engine ping. The blower will increase the effective compression ratio of the engine. A 7 psi blower pressure will raise a 7.5:1 compression ratio to an effective 9.8:1 compression ratio. An 8.5 compression ratio will be raised to an effective 11.2:1, and a 10.0:1 compression ratio will be raised to an effective 13.5:1 ratio.
The ZZ4 has 10:1 compression. You would need to run race fuel.
DETONATION ELIMINATION The increase in engine output with a Weiand supercharger does have the potential of causing serious engine problems (in one area), detonation, knock, or engine ping. The blower will increase the effective compression ratio of the engine. A 7 psi blower pressure will raise a 7.5:1 compression ratio to an effective 9.8:1 compression ratio. An 8.5 compression ratio will be raised to an effective 11.2:1, and a 10.0:1 compression ratio will be raised to an effective 13.5:1 ratio.
The ZZ4 has 10:1 compression. You would need to run race fuel.
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The 142 blower has 5 to 7 lbs boost.
DETONATION ELIMINATION The increase in engine output with a Weiand supercharger does have the potential of causing serious engine problems (in one area), detonation, knock, or engine ping. The blower will increase the effective compression ratio of the engine. A 7 psi blower pressure will raise a 7.5:1 compression ratio to an effective 9.8:1 compression ratio. An 8.5 compression ratio will be raised to an effective 11.2:1, and a 10.0:1 compression ratio will be raised to an effective 13.5:1 ratio.
The ZZ4 has 10:1 compression. You would need to run race fuel.
DETONATION ELIMINATION The increase in engine output with a Weiand supercharger does have the potential of causing serious engine problems (in one area), detonation, knock, or engine ping. The blower will increase the effective compression ratio of the engine. A 7 psi blower pressure will raise a 7.5:1 compression ratio to an effective 9.8:1 compression ratio. An 8.5 compression ratio will be raised to an effective 11.2:1, and a 10.0:1 compression ratio will be raised to an effective 13.5:1 ratio.
The ZZ4 has 10:1 compression. You would need to run race fuel.
Pro
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From: Texas
Chances are it is not a ZZ4 motor. Here the link to the ZZ4.
http://www.gmhorsepower.com/350-ZZ4-Turn-Key.php
http://www.gmhorsepower.com/350-ZZ4-Turn-Key.php
Last edited by Gunfighter13; Feb 16, 2019 at 03:19 AM.
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Pro
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From: Texas
He's running whatever the highest octane pump gas is around here - probably 91 - 93 octane. Would the detonation be audible like knock I've heard in other cars? I can tell you it ran really smooth - if there was any damage - cooking of the pistons presumably? - would it necessarily be evident?
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I have a boroscope, should a visual inspection of the piston tops be good enough to reveal any developing problems? I.e. if the pistons look fine they should be fine?
Team Owner
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From: Crossville TN
If the setup is all that good, why is he selling it? He might be having problems and wants to get our from under it....before it tanks. I wouldn't want to buy someone else's performance 'project', unless I knew the car and it had worked fine for a significant length of time. Sounds like a bunch of 'go-faster' stuff thrown together. Blower on a 10:1 compression engine seems "iffy" to me.
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If the setup is all that good, why is he selling it? He might be having problems and wants to get our from under it....before it tanks. I wouldn't want to buy someone else's performance 'project', unless I knew the car and it had worked fine for a significant length of time. Sounds like a bunch of 'go-faster' stuff thrown together. Blower on a 10:1 compression engine seems "iffy" to me.
This Vette is very intact - nary a trace of underbody rust, power windows work, all the gauges except the clock (of course) work, new suspension stuff, the headlights even work. If there's no damage yet, I suppose I could pull the blower and look around for lower compression heads. Seems that ZZ4 is pretty stout even without a blower.
Or alternately I wonder if I'd be better off finding a clean example with a low comp factory motor and put a blower on that.
Last edited by brassplyer; Feb 16, 2019 at 09:25 AM.
Le Mans Master
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From: Hermosa
Where are you at brass player?
could be at your elevation that a blower is fine on a 10:1 engine. Considering it’s a gm motor and advertised 10:1 cr it’s likely more like 9.2:1 Cr in reality anyhow.
could be at your elevation that a blower is fine on a 10:1 engine. Considering it’s a gm motor and advertised 10:1 cr it’s likely more like 9.2:1 Cr in reality anyhow.
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From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
If the setup is all that good, why is he selling it? He might be having problems and wants to get our from under it....before it tanks. I wouldn't want to buy someone else's performance 'project', unless I knew the car and it had worked fine for a significant length of time. Sounds like a bunch of 'go-faster' stuff thrown together. Blower on a 10:1 compression engine seems "iffy" to me.
Since you already admitted that you have no blower experience, you are playing with fire IMO. CR and tune are critical on this type of motor and if it has cast anything in it, I wouldn't even consider it. Again, just my opinion and playing it safe.
Le Mans Master
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From: Unreconstructed, South Carolina
Its L98 aka ZZ4 heads have tiny 58cc chambers (Not efficient Vortec shape)
Its pistons are flat tops with 4 VRs
https://www.chevrolet.com/content/da...e-24502609.pdf
zz4 and x603 CT variant are still used in circle track racing & I've had my hands and eyes on several freshenings
AFAIK ZZ4 /L98 heads no longer in production and same for ZZ4 & x603 crates
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Florida so essentially at sea level. Are the specs on GM crate motors notorious for being way off?
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Here's a few that show the engine bay and interior. There's also a front-facing scoop-type air intake, whatever the official name for those are.
Last edited by brassplyer; Feb 16, 2019 at 07:44 PM.
Thread Starter
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If the setup is all that good, why is he selling it? He might be having problems and wants to get our from under it....before it tanks.
Since you already admitted that you have no blower experience, you are playing with fire IMO. CR and tune are critical on this type of motor and if it has cast anything in it, I wouldn't even consider it. Again, just my opinion and playing it safe.
Besides the feedback I've gotten in here - which is appreciated - I've been exploring the 'net for info since encountering this car, I've picked up enough to get that there are lots of potential pitfalls. I've seen enough to question his competence, he apparently didn't adjust the ring gap which I find is considered crucial with a blower and the fact that he put a blower on this motor to begin with which I've seen stated in various places isn't a good choice of a motor for a blower without advanced detonation management which isn't in place.
Maybe there have been no ill-effects from this build but it's definitely a question mark.
Last edited by brassplyer; Feb 16, 2019 at 08:03 PM.
Le Mans Master
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From: Hermosa
In the link posted by Jackson note that it says compression is 10:1 NOMINAL, meaning, approximately, so unless the head has been cc’d as well as the piston it is only an approximation.
my 8.5cr L48 was in reality 7.7 :1. That kind of variation is going to make a difference.
that being said I can’t speak specifically to the zz4 head as I’ve never cc’d one.
Last edited by REELAV8R; Feb 16, 2019 at 08:07 PM.