Black 84 Z

So I did a search but didn't find what I was looking for, I am needing to replace the 350 that's been in my 84 Z28 for over 20 years. It never sees the track so I want to keep it street able and fun to drive. I've already replaced the TC with a 2500 stall and 3.73 gears. I'm wanting to do this on a budget and I found a local machine shop that is selling a ZZ4 spec engine with Vortec heads for a good price. Basically it's a 10:1 CR, vortec headed, carbed 355 with a ZZ4 cam (208/221 duration. 474/.510 lift) cam. It's not EXACTLY what I was looking for cam-wise as I was thinking of more like a Comp XE or Voodoo grind but the price is right. Realistically how much power will this engine make? The ZZ4 is rated at 355 with the vette heads so the vortecs should yield more. Is 375—390 reasonable for this combo? If it's close to that I should be happy as hell as my current engine is unspectacular. Thanks in advance!
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Komet

Probably more like 350ish.

Black 84 Z

Interesting, so it would make less power with the vortecs than the aluminum L98 heads given the same cam, compression, intake? I know the vortec chamber is a bit bigger but since the pistons used to build the short block are different to compensate for it.

aliceempire

iTrader: (14)

On an engine dyno with open long tubes, no air cleaner and no acc, sure 375 isn't out of reach Depending on the dyno too, which is the killer. They can all be different.
But that doesn't mean a ton once it's in the car. Attached to your exhaust, your air cleaner, etc, changes that all. And then it all has to transfer through your drivetrain and get to the pavement. What's that 375 mean now?
I realize you're probably just pondering your project but I wouldn't get hung up on a hp number. The end of the day it matters not. How well it moves and if it does what you want it to do, that's all that matters. A complimenting set of components designed to achieve what you want. Saying it has 375 hp and then running a 14 second quarter doesn't match. But running a 14 sec quarter could be fine if that's all the speed you want. Now, running 14s when you want to run low 13s, then that 375 is an extra worthless number. The car isn't performing as you want. So where's the restriction or failure on performance? Not so much whats my horsepower at.
My point is, it's all semantics. A legit 1000hp doesn't mean squat if the performance isn't there.
I feel like I got on a soap box for no reason.
Either way, 375 sure, maybe. Looks like a nice combo for a very streetable driver, good luck!

Dyno Don

iTrader: (7)

Better get some good gas for a steel headed 10:1 motor
it will ping like hell on 87-91 octane.

ULTM8Z

I'm not convinced it's 10:1. There are some variables to sort out here...

The ZZ4 comes rated at 10:1 with 58cc L98 heads and a .051 thick head gasket.

If I swap to 64cc Vortec heads, that drops the compression ratio to 9.36:1

The thinnest composite head gasket you can get (to my knowledge) is GM's .028 gasket. Swapping to that gasket gets me back up to 9.85:1.

If I use the more typical .039-.040 gasket, I'd get 9.59:1.

That said, Don is correct... iron heads are going to be prone to pinging on 91 octane. I tried 10.1:1 with AFR aluminum heads, computer controlled fuel/timing and 91 octane and couldn't get away with it. I had to drop down to 9.8 before I eliminated the pinging (and again, that was with aluminum heads).

I think iron headed Vortec engines have run about 9.3:1 max, but even with that, I'm not sure what octane.

You may want to ask the owner what gasket he used. If it's truly a 10:1 engine, I'm with Don... you're likely going to have problems.

Berlinetta00

I get detonation under part throttle 4th gear acceleration somewhat frequently with factory heads on my ZZ4 using 91 octane. The ZZ4 heads are easy to find as well, Id just as soon pop off the vortec heads and swap whatever aluminum heads on there you prefer. Some of the builds that hot rod magazine has done over the years netted almost 400 ponies with the factory cam and a head swap.

All that said, I love the ZZ4 as a rock solid performance engine, I have had mine in there for 15 years with no complaints. I thought long and hard about replacing the heads or cam, but it just works so well as is that loosing any reliability or longevity for the sake of a small performance gain isn't worth it to me. If they say it's 355 ponies, much of that must be getting to the ground because that car is stupid fast at WOT.

Black 84 Z

Thanks so much for the replies guys! I haven't run the numbers on the actual components used in the build to find the actual CR since it's not just a head and cam swap but a full rebuild with new components . My first though when I read the description was that it was a bit undercammed and second was the CR is high for iron heads and that cam. It was well priced but if I have to swap the cam and/or heads to get it to be reliable on the street then no deal.

Fast355

iTrader: (2)

My old 383 was 10.5:1 with vortecs. 32° total timing at 3,600 and upwards of 50 at cruise and no pinging on 91. My new 383 is 11:1 with aluminum heads. 34° total @ 3,600 and 44° at cruising rpm with no pinging on 91. Quench is make or break important.

Fast355

iTrader: (2)

I went from factory 0.028 compressed gaskets to 0.016" shims on my L31 in my 97 Express. Heads milled 0.020". 9.75:1 static with the 12cc dished Vortec pistons. Cam was the little 395' 196/206 @ 0.050 on a 109 LSA, degreed on a 106 ICL . Lots of cylinder pressure and it ran fine on 91 octane at 31° total advance. It would occasionally show knock retard in hot weather while towing. It pinged less with tighter quench and more compression than it did with open quench and less compression. Factory vortec is 9.4:1 and runs about 24° of timing on 87 octane.

robertfrank

iTrader: (27)

I helped a friends build a vortec headed, ZZ4 cammed engine a few years ago. It was a 355 880 block with flat top pistons. With an edelbrock rpm intake and a 650cfm carb it made 302hp through a T56 and 2:73 gears on a chassis dyno.