I currently have a C4 race car with a tired and worn out ZZ4 motor. Rather than rebuilding the motor, I was considering one of the new ZZ6 EFI crate motors from GM. Has anyone done this swap? A few questions that run through my mind are; 1) Would this be a direct bolt on replacement? 2)Would the new intake with a carberator style air filter fit under the hood? 3)Would I be better off installing the stock C4 intake on the ZZ6? 4)Any other considerations I'm missing?

 

I think you will need a hood scoop for carburetor.

 

Why would you buy a Brand new EFI Engine and use a carburetor?

GM might have a few new trick fuel injection systems that might fit but they frequently come complete with the Boxes they need.

 

It's not a carburator, it's EFI but it is meant to look like an old school engine so it has an air filter on top. It's the only way the ZZ6 motor comes from GM.

https://www.summitracing.com/parts/n...hoC7FYQAvD_BwE

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I think I would save myself about $3k by buying a 383 long block and dressing it in all the external parts from the ZZ4. https://www.summitracing.com/parts/m...3ct1?rrec=true

 

Joshie225 I considered going the route you sugguested initially, but had some concerns that made me still lean towards the ZZ6. These blueprint engines have much cheaper internals, cast iron crank, etc. I'm conserned that that won't be able to hold up to the race abuse. The ZZ6 has forged internals, and generally better quality parts. This particular stroker you sent in the link also isn't compatible with fuel injection. I would prefer to buy a ZZ6 motor without the "carburator style" EFI intake, but they don't offer that as an option. So my question is will this "carburator style" EFI intake fit under the hood of C4, and if not will I be able to use the stock C4 EFI intake?

 

The zz6 uses the same heads as the zz4, so you could swap intake IDK how that would effect horsepower. Other option could be one of 2 zz partials, recondition you heads, transfer or change cams and other parts as you wish during reassembly.

 

Thanks to everyone for the insightful comments.

For a little more background on my existing motor, it is a ZZ4 that's over 10 years old, has an eagle forged crankshaft, ZZ4 cam (at least that is what the previous owner listed), not sure on heads but I assume stock zz4, the original production C4 intake. The motor requires 100+ octane due to the compression ratio, previous owner ran 110 octane race fuel. The motor shows 300+ (race) hours on the engine. Original Dyno numbers from the previous owner were 325 HP and 387 Torque at the wheels, current Dyno numbers are 199hp and 262 torque at the wheels, I can confirm the later numbers are accurate as I could tell it was way down on power on the track. Given the age, hard use, compression ratio (I would like to run 93 octane), Im thinking a new motor may be a better route than a rebuild.

Having said all that, I'm thinking about trying the ZZ6 crate motor, and if the included EFI carburator style intake doesn't fit, maybe I can use my stock C4 intake, but not sure how that would impact hp, and assume it would likely require dynotuning? I couldn't find a ZZ6 long block that didn't come with an intake, or another crate 350 with strong internals. Goal is cheapest way to get reliable 400+ hp for racing out of a 350 block (bolt in without significant mods).

 

I have a GMPP ZZ4 short block brand new still in the crate. GMPP roller cam and matching valve springs, new set of head bolts. Would be a direct replacement for your worn out engine.

 

The ZZ4 is advertised to have 10.0 compression ratio. Not sure why you would need to run 100 octane to achieve 325-199whp.

 

GM crate engines come with all GM parts. No eagle, scat white, ohio... etc parts. It will have to come apart to find out what's in it.

 

Hello StealthVette05!

That complete bottom end might be a good way to go!
If it has 10-1 Compression it should not need high octane gasoline. I run 12.25-1 in my L71 427 (BBC) engine on pump gasoline. Yes it does like the octane but will happily run without it. It really boils down to the design of the cylinder head, some of the newer open chamber heads have real issues with detonation. I am still using a GM cast iron heads and they work without any issues, I wish I had aluminum versions of the closed chamber cylinder heads I am using.

If you are really worried about the compression being too high there are plenty of ways of dealing with it. I have a Snow performance Water/Methanol injection system for my C3, it simply starts squirting the windshield washer fluid into the intake and gives me the equivalent of 116 octane race fuel. I tried the system on my C3 and liked the way it helps. I can put 87 octane into my 12.25-1 engine as long as I have the extra octane from the water/methanol I will not hear any pinging. I even converted my old Cadillac STS to use the Snow Performance injection and it helped save me some money. Afterwards it was happy drinking the 87 octane fuel getting 12 miles per gallon.

Creative timing is another way to deal with high compression engines. My 427 did not like to start when warm as the factory starter was not strong enough for the compression. I added a device that pulls the timing back 20* while cranking and when it starts the timing returns. This could have worked with my factory starter but it was installed after a Gear drive starter was installed. Now my Corvette sounds like a Chrysler when cranking. I installed a oxygen sensor allowing me to monitor my mixture and a light connected to a MSD Knock Sensor to warn me of any pinging.

Best regards,
Chris

 

I am considering it and have done some research. Not for my C4 but for my Thirdgen.


To a ZZ4, yes. It is a SBC just like the rest of the ZZ's and any other SBC out there.

Not on a C4. The carb will probably fit but without a custom air cleaner... no. I have seen soem fabbed air cleaners for C4's but not the off the shelf ones.

Not being very specific here... Xfire, TPI, LT1/Lt4 Style? The ZZ6 has fast burn Vortec bolt patter heads on it. Both the Mini Ram and FIRST offer intakes in this style. As well as plenty of options for carbs. Using the factory L98 or Crossfire would be... not worth the work to make it fit IMO as it will choke the ZZ6.

The ZZ6 is a nice package, makes good power without an exceptionally high compression ratio. You consideration is to save money and put an engine together yourself or buy a lesser brand for less money.

Basically the ZZ6 is an SBC with a one piece rear main. If you have an SBC in anything, the ZZ6 will drop in. It will not care if it is a crab or an injection set up feeding it just like any other SBC. It will change the output based on the type of intake you use. Jegs sells it without the carb for around $6500, but does have the intake. I am thinking of going this route with a FIRST system on top instead of an LS swap for simplicity. My accessory drive bolts right up to it and I can keep my supercharger. A lot less homework than doing an LS swap and I think with the 6PSI through a first it should make 450 or so HP and just a load of torque around 3500-4000RPM.

 

Plenty of options for how it comes dressed. The engine will not care if you run it with a carb, miniram, FIRST, FI Tech... or any other air/fuel delivery system that can sit on an SBC. Hood clearance on a C4 is next to nothing. If it is taller than a TPI assembled, you are out of room basically.

 

That motor is not fuel injection.

throttle body fuel injection is a fancy name for a carb with some wires sticking out of it