ThirdGen,
I live in Austin, TX. I've posed this question to the local ThirdGen group as well, but wanted to get the advice of a larger audience.
My plan is to replace the 305 in my '88 Formula with the ZZ4 350 crate motor and upgrade the TBI. My question is: has anyone done this? Were you able to pass emissions? What sort of results did you see, assuming you didn't move to a carb?
Any ideas or feedback you can give me would be a huge help. Thanks.

 

Nothing about the ZZ4 itself will cause failure. The heads were still being used on the '91 'vettes. The cam is clean enough to pass in '97 LT1s. It's all gonna be in the tune, which is in the PROM chip. There are many intake manifolds you could use, but only 2 are truly outright legal, and only one is worth fitting to a ZZ4: the Edelbrock Performer TBI. The good news for you is that it does flow just as well as the ZZ4 intake.
There's a company in California that can help with this project, despite their name: Turbo City.
Holley's 570-cfm TB will be necessary for adequate flow, but isn't technically legal for your app. still, it's a direct bolt-on.
Use Hooker 2055 headers with Y-pipe, they have all the necessary provisions for the emissions stuff. Hedman offers similar, but their Y will choke the ZZ4, and their collectors are too big. Don't go Hedman. The Edelbrock headers are also restrictive. If you want stainless, choose MAC Performance. Theirs are very much like the Hooker 2055.

 

That's a huge help. Thanks. You actually answered a few questions I didn't even ask yet. I have two other questions.

1) I've seen alot of comments about having to replace the fuel pump with an engine upgrade. But this may be for a larger engine with more HP. In your opinion, will I need to go with a better flowing fuel pump?

2) With 400HP at the flywheel, will I need to go with a different rear end? What parts will I need?

 

EBL flash would be of great help, since efficiency/precision is the key for meeting emissions standards.

1. Yes, a smaller injector with higher pressure is more efficient. Will need to be combined with a VRFPR. (like every standard "high" fuel pressure set up)

2. Isent the zz4 350fwhp?

 

When i lived in H-Town i installed roughly 35 zz4s for various customers and they never had a problem with emissions. We were concerned when they came out with the stations where they put the car on the dyno to simulate actual driving however my buddy put his 91 Z28 w/408,SLP T-ram,SLP headers 1 3/4s,A4 on the dyno passed easily and ran 11.8s at HRP car had both cats,smog pump no egr this happened in '94...
The zz4 has a very nice cam in in there and will pass emissions as long as you have a properly tuned car fresh plugs,wires, cap&rotor

 

How, exactly, do you propose to get from 355 hp up to 400 hp? That 355 rating is with headers, so that won't do it. TBI won't help you, either. Maybe you're thinking of a 45-shot of Nitrous?
Your stock rear end will live, unless you're into seriously abusive driving on sticky tires. But seriously consider a 3.73:1 posi for it.

 

You'll need a better fuel pump than the stock TBI unit.

 

Isn't it the same one used in the old 454SS pickups? That one will support a ZZ4.

 

The 400HP was my mistake. I meant to write 400TQ. I believe that's the rating: 355HP and 400 or 405TQ.

And you think the Holley 670CFM will be enough for the ZZ4? I was thinking either the Holley 670 or a refurbished GM throttle body from the big block.

 

I've never checked the p/n's of the two applications, but the 454SS was only rated at 230 HP.

You might get by with it, but I wouldn't want to rely on it, especially if the pump is 22 years old.

 

'91-'93 was 255 HP, and, more relevantly, 405 ft-lbs.