joebobo32

I installed a ZZ383 this year in my '69 Camaro. I know some have installed in their C3s. This past month I received a notice that GM acknowledges the horsepower numbers are off unless the engine is modified. They are offering $700 cash, which you can pocket or use to get the requisite parts (160 degree thermostat and 16 1.5 roller rocker arms) to get the proper horsepower. You also need to sign a waiver.

If you bought one of these engines, email ZZengine@abcoop.com or call 888.980.6148.

My letter came from Summit. I saw some folks discussing the issue here also - http://www.onallcylinders.com/2014/1...5-crate-motor/ Scroll down to the comments from July 2015 or search for recall.

jb78L-82

Your post is interesting on a number of fronts....

1. I am not surprised about the inflated HP numbers since I have always looked at the specs for the 383/350HO ZZ4/ZZ5 and wondered how GM is getting those GROSS HP numbers. I have looked at the cams in both engines-lift, duration, LSA-compared to my Howards Roller cam in my 355 L-82-and was always puzzled???? Combined with the GM heads which are no way near as good as the AFR's on my build and compressions in the 9.5 range, I was dubious about the numbers..

2. So much for the doubters that running a 160 theromostat AND roller rockers does not add significant HP to a motor...proof positive on these issues since GM says you need both for 15-20 additional HP. Post that fact in a separate thread...you should get some attention...

3. Nothing new about the fact that all crate engines are GROSS HP, NOT NET, as installed in cars today. So, installing a 383 Crate with 400 GROSS HP in a SUV that had a say 290 HP NET engine is not a 110 HP increase...not even close. Deduct 15% off the Gross HP number to get the NET HP number for an apples to apples comparison between the old and new engines. Using Gross HP/TQ for crate engines is somewhat misleading to the buying public since NO ONE uses Gross numbers any longer (40 years now) on engines installed in a car/truck because the power of the engine as installed is NOT that rating with all accessories hooked up and a full exhaust. Its like saying I paid $300 for an airplane ticket without Taxes, Fees, etc which could make the real cost $380 for the ticket. Did you actually pay $300 or $380?

gdh

Thanks for the info, I emailed the add'y you listed with pics of my rec'ts. Bought the new zz383 deluxe May 2014 from a GM dealer up here in Ontario Canada. Will wait to hear back from them. The email bounced back, changed it to ZZ5Engine@abcoop.com. Will see what happens, I'll call the no. and dealership as well to make sure that the ZZ383's are included.

Talked to the GM rep, the ZZ383 deluxe is part of the recall. She emailed me the waiver, said it would take 6 - 8 weeks to rec the cheque.

gdh

As an update, just talked to the co. handlng this. My claim was approved and I should rec. the cheque in 2 to 4 weeks. I couriered my documents down with a signature req'd. The docs arrived Nov. 17th, will update when the cheque arrives.

mikem350

The crate motors come with mild cams, for long life/warranty purposes.

The roller rockers crutch the mild cam and the 160 thermo allows for more timing, gaining enough to squeak thru the HP rating legally

At least you will get a nice check, just in time to help pay Holiday credit card bills...

gdh

Once warranty is up I may look at a new cam. I'm still enjoying the motor but may change the cam in a couple of years.

69427

I disagree. The manufacturer (of any crate motor) has no idea of what the particular exhaust system is or the level of its efficiency that will be installed on any of the thousands of engines they sell. They also have no idea of what combination of accessories (and belt/pulley speeds) that will be installed on the engine. The crate motor manufacturer therefore has two choices: publish the gross horsepower of the basic engine (the "combination" that the manufacturer can actually control and measure), or to just make a guess (such as a 15% derating factor, but what happens if your competitor decides he wants the derating factor of his engines to be 10% for his marketing/sales strategy?) of what the net power is.

Jason Staley

GM has no other way of rating crate engines. They have no way of knowing what the NET Hp will be in your particular application. It's really up to the consumer to become educated about something before making a purchase; not too much to ask IMHO.

Now if GM isn't even making the GROSS Hp advertised, that's a whole other issue, and they seem to be trying to correct that with the payment to customers.

cagotzmann

I thought the same but what about the LS3 Engine. or the LS7 Engine

LS7 Crate rated @ 505 HP
http://www.chevrolet.com/performance...gines/ls7.html

LS3 Rate rated @ 430 HP

http://www.chevrolet.com/performance...gines/ls3.html

This is the same as C6 Corvette's from the factory. I dont think the Factory rates the engines using GROSS ?????

jb78L-82

Crate engines are rated as gross HP UNLESS said engine is a production engine installed in a production vehicle, aka ls3/ls7 then it is rated as net hp as installed in a production car....so much for a manufacturer not knowing the net hp rating....

As for not not knowing what application the engine will be in to achieve a net HP rating, all the engine manufacturer has to do is hook up all basic accesssories to the engine (water pump, PS steering pump, Alternator etc) AND a dual 2 1/4/2.5 inch full exhaust with mufflers of moderate restriction on a non pollution controlled vehicle (no cat) with OEM exhaust manifolds and bingo you have a fairly good Net HP number...guys this is not hard to do...Gross is done simply for most engines because a ZZ4/5 ZZ385 etc having 385 No Name Gross HP sounds better than 305 Net Hp as an example...There is no mystery here....just marketing

69427

Those net ratings are only accurate if those engines are put into a very limited number of stock GM models. Any other vehicle and Chevrolet has no clue what the net hp of those two engines would be.

cagotzmann

Marketing misguiding misleading. From how the numbers are displayed in the gm pages with no "asterisk" "Note" indicating how they got this number, you would be easily mislead on the other engines throughout the catalog. Just as GM intended. I guess this is the same as everyone else selling crate motors.

I knew the ZZ383 rated at 425 / 450 vs the LS3 they are not the same. I have a ZZ383 in my 78, and a LS3 in my 2010 GS. Both running 6 speeds and the 2010 GS tops at 112 MPH vs 104 MPH in the 1/4 Mile. I am guessing the ZZ383 @ about 350-375 net in my application.

jb78L-82

Not true...GM uses the same engine quite often in Mutliple vehicles and the Net HP usually varies by a small number....Last call on this for me, publishing a Net HP number is NOT hard for an engine manufacturer to do..it is NOT done since it will not highlight the performance in the best light for marketing purposes,.....Period!

jb78L-82

Spot On !!! Glad you get the point...

Any engine manufacturer should have to test the engine with all accessories hooked up as it would be in a typical application with a full exhaust (OEM or LTH...just needs to be noted) and again BINGO NET HP. Any engine installed in a vehicle is not GROSS HP....thus Crate Gross HP is misleading at best.....BTW the reason that Gross HP was dropped in 1972 by the SAE since the number was MISLEADING......and NOT accurate for an engine installed in a vehicle...any vehicle

69427

Sorry, not last call for me.

You cannot, I repeat, cannot put the same engine in multiple configurations of accessory loads and exhaust backpressure levels, and get the same reading of flywheel/dyno horsepower. Horsepower read on the dyno, whether net or gross, is what's available at the flywheel. If you change the accessory loading at the front of the crankshaft, or change the VE of the engine by changing the exhaust, you will get a different hp reading at the flywheel. It's basic physics.

Feel free to explain where you disagree with the physics here.

96 lt-4

Or you could spring for some 1.6 roller rockers,do the t-stat,and pocket the difference(or use towards labor).Nothing wrong with swapping the cam but I would be looking at roller rockers regardless.

bluedawg

Part of the difference is that the 78's rear gear eats more power.

MotorHead

So since the LS7 installed in a C6 Corvette is 505HP NET they could and should dyno the engine without any thing attached and get near 600HP Gross and advertise that number.

The only reason they don't is because most people will not "get it" when they offer a ~600HP LS7 as a crate engine and the same engine is only 505HP in their Vette. Big can of worms here and I do believe the LS7 is closer 550+HP

cv67

x3 on no way to show net every car will need something different

Marketing is part of owning a biz if you dont do it youll be looking for a job. Id trust a GM product before I did some out of state new kid on the block ebay rebuilder. Nothings perfect

Kevova

GM extending end user compensation program until June 30 2016 due to lack of response. Chevrolet Performance found that HP was off 2-3%. There is a wavier involved which must be completed. The HP short coming will not effect durability and waiver doesn't effect warranty. For questions email ZZ5Engine@acbcoop.com or call 888.980.6148