ZZ4 vs. GMPP 290 HP Octane consideration
Thread Starter
Melting Slicks
Joined: Jul 2013
Posts: 3,237
Likes: 31
ZZ4 vs. GMPP 290 HP Octane consideration
1981 Corvette - AT, 100% stock, 60K miles. I have been given the green light by the wife to order a new motor for Christmas!
I live in Alaska and I can only get 90 Octane on a regular basis at most gas stations. This a daily driver and I DO NOT want to mess with octane booster for daily driving.
The ZZ4 "recommends" 92 Octane and the 290 HP "recommends" 87 octane fuel. Any idea how serious this "recommendation" is?
Knowing that I will be able to run at best 90 Octane, will I have to retard the timing on the ZZ4 to keep the pinging down? And if so, will the retarding wind up lowering the HP to the point that I won't get enough difference over the 290 HP?
I suspect that I will still have some HP advantage with the ZZ4 even if I tune it down a bit, but at almost twice the cost I am worried that it won't amount to a hill of beans at the end of the day.
Do some of you guys that really know a lot about tuning motors have a guess as to how much I will loose if I have to tune down the ZZ4 a bit considering my fuel situation?
Or am I just worrying about nothing?
I live in Alaska and I can only get 90 Octane on a regular basis at most gas stations. This a daily driver and I DO NOT want to mess with octane booster for daily driving.
The ZZ4 "recommends" 92 Octane and the 290 HP "recommends" 87 octane fuel. Any idea how serious this "recommendation" is?
Knowing that I will be able to run at best 90 Octane, will I have to retard the timing on the ZZ4 to keep the pinging down? And if so, will the retarding wind up lowering the HP to the point that I won't get enough difference over the 290 HP?
I suspect that I will still have some HP advantage with the ZZ4 even if I tune it down a bit, but at almost twice the cost I am worried that it won't amount to a hill of beans at the end of the day.
Do some of you guys that really know a lot about tuning motors have a guess as to how much I will loose if I have to tune down the ZZ4 a bit considering my fuel situation?
Or am I just worrying about nothing?
Burning Brakes
Joined: Sep 2012
Posts: 818
Likes: 0
From: coon rapids mn
what are the cost of both engines ?consider a 383 sbc with dish or flat top pistons ,and add some large chamber 76cc aluminum heads .pick out the parts and figure out the static compression before buying any thing .then add a cam that makes the dynamic compression ratio safe for 90 octane .what do most snowmobiles up there run on ?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You better go back to school!!!!!!!!!!!! 
In the north you have to live below the year around snow line. Also the majority of paved roads are only near the coast where the majority of the states population lives. That is why they call it the frozen North!
Even where he said he lived in Anchorage (right on the Ocean that also freezes solid). Almost all roads are packed snow and ice through middle of May. Then by early June the plants turn it into a jungle because of nearly constant sun light. the snow maybe recedes up the mountains to about 2500 before it starts snowing again in the fall.
I didn't go measure 2500 feet, but I'm telling you stuff up north is snow capped year around.
I would suggest that everybody needs to put Alaska on their bucket list.
To the poster. California only sells 91 octane. I'm not sure why they think they need 92 octane because they are lower compression motors like 9.6 with aluminum heads
In the north you have to live below the year around snow line. Also the majority of paved roads are only near the coast where the majority of the states population lives. That is why they call it the frozen North!
Even where he said he lived in Anchorage (right on the Ocean that also freezes solid). Almost all roads are packed snow and ice through middle of May. Then by early June the plants turn it into a jungle because of nearly constant sun light. the snow maybe recedes up the mountains to about 2500 before it starts snowing again in the fall.
I didn't go measure 2500 feet, but I'm telling you stuff up north is snow capped year around.
I would suggest that everybody needs to put Alaska on their bucket list.
To the poster. California only sells 91 octane. I'm not sure why they think they need 92 octane because they are lower compression motors like 9.6 with aluminum heads
Last edited by gkull; Dec 7, 2013 at 03:15 PM.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
What are your priorities? Direct, drop-in replacement? 290hp engine is the ticket. Even if you plan to boost performance, it will satisfy with replacement parts (on your schedule) up to about 400hp. Beyond that, the ZZ4 would be the better platform to begin from.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The ZZ4 at 10:1 would *probably* be OK with a full advance curve and 90 octane...but it is right at the edge. I base that on a 10.2 engine I built that would not run full advance on 89 octane, but did fine on 92.
There are a lot of other crate choices between these two, including the 350 HO and many from other vendors that would live just fine on 90 octane.
The 290 is fine for a lo-po motor, but I wouldn't go into it expecting to build power on top of it. Cast crank, cast pistons and PM rods. I personally would not push more than 1 HP/CID through that combo. Keep in mind there are shotblocks available as well, that you can add exactly the cam and heads you want for your application.
There are a lot of other crate choices between these two, including the 350 HO and many from other vendors that would live just fine on 90 octane.
The 290 is fine for a lo-po motor, but I wouldn't go into it expecting to build power on top of it. Cast crank, cast pistons and PM rods. I personally would not push more than 1 HP/CID through that combo. Keep in mind there are shotblocks available as well, that you can add exactly the cam and heads you want for your application.
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Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
The ZZ4 at 10:1 would *probably* be OK with a full advance curve and 90 octane...but it is right at the edge. I base that on a 10.2 engine I built that would not run full advance on 89 octane, but did fine on 92.
There are a lot of other crate choices between these two, including the 350 HO and many from other vendors that would live just fine on 90 octane.
The 290 is fine for a lo-po motor, but I wouldn't go into it expecting to build power on top of it. Cast crank, cast pistons and PM rods. I personally would not push more than 1 HP/CID through that combo. Keep in mind there are shotblocks available as well, that you can add exactly the cam and heads you want for your application.
There are a lot of other crate choices between these two, including the 350 HO and many from other vendors that would live just fine on 90 octane.
The 290 is fine for a lo-po motor, but I wouldn't go into it expecting to build power on top of it. Cast crank, cast pistons and PM rods. I personally would not push more than 1 HP/CID through that combo. Keep in mind there are shotblocks available as well, that you can add exactly the cam and heads you want for your application.
Last edited by TedH; Dec 7, 2013 at 10:08 AM.
Melting Slicks
Joined: Aug 2005
Posts: 2,683
Likes: 34
From: Working on the car NY
I would not buy any engine nowadays with a flat tappet cam. I think the base ZZ4 at 355 hp (without the fast burn heads) is the best buy out there. Alum heads and intake, forged (granted not 4340) crank, roller cam, 400+ ft lbs torque etc 
- but I'm running #93. I'd be careful running under what GMPP recommends. My .02 FWIW.
- but I'm running #93. I'd be careful running under what GMPP recommends. My .02 FWIW.
Thread Starter
Melting Slicks
Joined: Jul 2013
Posts: 3,237
Likes: 31
290 it is -
It sounds like the consensus is that the ZZ4 will probably work with 90 Octane although I might have to tune it down just a bit to play it safe. Warranty is a concern but I wonder if Chevy would actually ever check my fuel on the odd chance that I have a problem anyway.
I appreciate the advice about possibly going to 290 route and building up to something similar (in HP) to the ZZ4.
My current motor is just too weak to make the car fun to drive. If I could get 0-60 in 6 to 6 1/2 (never timed it but specs say stock motor is 8.1 seconds) I would be content for a daily driver. In my earlier days I had a 70 GTO that I went overboard on the HP and it became too much of a beast to run around town in. I want to avoid that on this one.
Knowing that I will probably never want to go above 355 HP (zz4) on this particular car. I am inclined to go with the 290 at half the cost. If it turns out to be too slow. I can build it up a bit to a respectable 330-350 without over doing it on the crank and block.
I appreciate the advice about possibly going to 290 route and building up to something similar (in HP) to the ZZ4.
My current motor is just too weak to make the car fun to drive. If I could get 0-60 in 6 to 6 1/2 (never timed it but specs say stock motor is 8.1 seconds) I would be content for a daily driver. In my earlier days I had a 70 GTO that I went overboard on the HP and it became too much of a beast to run around town in. I want to avoid that on this one.
Knowing that I will probably never want to go above 355 HP (zz4) on this particular car. I am inclined to go with the 290 at half the cost. If it turns out to be too slow. I can build it up a bit to a respectable 330-350 without over doing it on the crank and block.
Pro
Joined: Apr 2004
Posts: 621
Likes: 37
From: Texas
What about the HT383 ?
Same power, more torque,9.1 to 1 compression
there is nothing worse than fighting to much compression.
when you retard the timing the motor doesn't do anything right anymore, starting with the idle.
I fight it sometimes even with my 9.4-1 motors.
I have always been a big fan of the ZZ4 but for this reason I would pick the ht383 over the ZZ4 now.
Same power, more torque,9.1 to 1 compression
there is nothing worse than fighting to much compression.
when you retard the timing the motor doesn't do anything right anymore, starting with the idle.
I fight it sometimes even with my 9.4-1 motors.
I have always been a big fan of the ZZ4 but for this reason I would pick the ht383 over the ZZ4 now.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Just to satisfy my own curiosity, I looked up the specs of the zz4 cam, and ran the numbers through my DCR calculator, and I get a static compression ratio of 9.94:1, and a dynamic compression ratio of 7.99:1. I think that's cutting it a little close for 90 octane gasoline, especially since the .051" head gasket gives the engine a quench distance of .076", which is not exactly optimal.
I haven't bothered to run the numbers for the 290 HP engine, but just from looking at the specs, I would guess that you could probably run it on kerosene without any problems. It's DCR is probably less than 7:1.
Scott
I haven't bothered to run the numbers for the 290 HP engine, but just from looking at the specs, I would guess that you could probably run it on kerosene without any problems. It's DCR is probably less than 7:1.
Scott
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
The O/P aint spending the money on more then the 290hp .. I think he just needed some reassurances and he was talking octane to get himself to the 290 motor.
As long as he is ok with that .. it is all good .
As long as he is ok with that .. it is all good .
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
It sounds like the consensus is that the ZZ4 will probably work with 90 Octane although I might have to tune it down just a bit to play it safe. Warranty is a concern but I wonder if Chevy would actually ever check my fuel on the odd chance that I have a problem anyway.
I appreciate the advice about possibly going to 290 route and building up to something similar (in HP) to the ZZ4.
My current motor is just too weak to make the car fun to drive. If I could get 0-60 in 6 to 6 1/2 (never timed it but specs say stock motor is 8.1 seconds) I would be content for a daily driver. In my earlier days I had a 70 GTO that I went overboard on the HP and it became too much of a beast to run around town in. I want to avoid that on this one.
Knowing that I will probably never want to go above 355 HP (zz4) on this particular car. I am inclined to go with the 290 at half the cost. If it turns out to be too slow. I can build it up a bit to a respectable 330-350 without over doing it on the crank and block.
I appreciate the advice about possibly going to 290 route and building up to something similar (in HP) to the ZZ4.
My current motor is just too weak to make the car fun to drive. If I could get 0-60 in 6 to 6 1/2 (never timed it but specs say stock motor is 8.1 seconds) I would be content for a daily driver. In my earlier days I had a 70 GTO that I went overboard on the HP and it became too much of a beast to run around town in. I want to avoid that on this one.
Knowing that I will probably never want to go above 355 HP (zz4) on this particular car. I am inclined to go with the 290 at half the cost. If it turns out to be too slow. I can build it up a bit to a respectable 330-350 without over doing it on the crank and block.
Scott
Pro
Joined: Apr 2004
Posts: 621
Likes: 37
From: Texas
L31 Vortec are by far the best crate motors for the money.
that is, if you can do without the fuel pump boss.
http://www.summitracing.com/parts/na...FWUV7AodogIAKg
that is, if you can do without the fuel pump boss.
http://www.summitracing.com/parts/na...FWUV7AodogIAKg
Melting Slicks
Joined: Aug 2005
Posts: 2,683
Likes: 34
From: Working on the car NY
L31 Vortec are by far the best crate motors for the money.
that is, if you can do without the fuel pump boss.
http://www.summitracing.com/parts/na...FWUV7AodogIAKg
that is, if you can do without the fuel pump boss.
http://www.summitracing.com/parts/na...FWUV7AodogIAKg
. Fitment under the hood could be a problem especially with the med rise intakes like on the ZZ4. I had to go with a 2 1/2" air cleaner element (vs. the stock 3") on my ZZ4 to clear the hood - and it just made it.