All I can tell you is that a friend of mine with a 79 L-48 put in a GM crate motor rated at 290 HP and he was very disappointed with the difference in power between the "290 HP" crate engine and his L-48. No dyno numbers but that pretty strongly indicates that the crate engine was rated at gross HP, not NET. I still say that a ZZ4 crate motor is probably good for 290-300 Net HP, not 355 Net HP, like a production engine installed in a car with a full exhaust and all accessories running on the car and running. Gross to Net is gross to net ratings, regardless of when it was done.

 

Better off spending the money on a good 5 or 6 speed, or a different rear end gear.

I put a Richmond 5 speed in my '81, it feels like I gained 50hp on the butt dyno. LOL

 

So has anyone with a zz4 actually had their car on the dyno ??

 

Not the ZZ4 but Year One's similar version Power Crate 350 with cast heads and my car made 311 to the tire through all mechanical accessories (A/C, PS, Mechanical fan & fuel) and a 200-4r. This was a 400hp rated motor and is very similar to the ZZ4.

I think someone cleared it up earlier but these ratings are not at the back tire so a C6 505 hp motor is the same a a crate LS7 505 hp motor. It is all at the crank. Additional (or less) drive accessories and power train will dictate how much of that power actually gets put to the pavement.

 

311 is pretty good mine did 225 with just headers 74 l82 4 sp all stock with headers
I was looking into getting a zz 4 I guess anything over 300 at the wheels is pretty good

 

I seriously doubt a ZZ4 crate engine would put anywhere near 311 rwhp totally stock with cast iron manifolds. 265-275 rwhp is more likely. A 400 gross HP year one engine I would expect to lose 90-100 HP from the crank to the wheels- that sounds right and in line with a crate 383 doing about 320-325 at the rear wheels. A production LS7 Z06 loses about 50 HP from the net 505 rating to rwhp-450 HP and that's with a much higher starting point Net 505.

 

a 3rd gen Fbody put up 271hp and 368ftlbs with a ZZ4. found that with a quick google search

 

Well there you go!! Thanks for that documentation-awfully close to my prediction above of 265-275 Rwhp for a ZZ4!!! Crate engines are rated at GROSS NOT NET HP, unless the motor was installed in a production car.

My initial comment on this subject was precisely to correct crate motor HP misinformation. Most folks don't seem to want to accept that their "350/400" HP crate engines are not equivalent to Net HP numbers in production cars, for the most part.

 

I just got quoted 5700 from a gm dealer on a zz4 too much I think
But I am in Ontario Canada

 

All I know is that mine goes like a bat out of hell! I had an L-79 327/350 HP and the ZZ4 is way faster, but it is so smooth at idle that I miss the lumpty, lump of the L-79. Lou.

 

First off thats not what you said , You never said RWHP you specifically stated Gross hp is how there rated then went on to suggest there only 290 net .. That statement is 100% inaccurate. All motors are tested by the SAE net standards, NOT GROSS that testing died off 40 plus years ago.

WHAT he just said is a car on a dyno had RWHP and if you do the math it comes out to approx 20% loss from crank to the rear tires making there claim of 355hp almost 100% dead on. I bet he has A/C and the dyno motor does not.

For those reading this , realize all testing is done to the SAE net standards. What that means on a crate motor is what they reasonably believe the motor will have installed , and yes they are using high flow exhaust ( Headers) and a good carb and intake . Alll of which you can purchases from them or jegs for that matter.

There not taking a motor with no water pump , open headers , high rise intake and going ***** to the walls to hit a number , that was the old days , today there actually setting it up in a basic configuration you can expect to see on an older street car .

So if you want 355 crank hp ,, ZZ4 is it and someones subjective comparison there old L48 vs the new 290 hp motor is a disappointment is a meaningless statement as we have no idea how he has it set up for all we know he has a bad float setting on his carb or his timing set wrong or a vac leak ...

 

Everyone is entitled to their opinion. The readers can decide.

You keep stating this:

All crate engine manufacturers state only that the engines are measured according to SAE standards.

Below are SAE standards:

Engine power test codes [edit]

Engine power test codes determine how the power and torque of an automobile engine is measured and corrected. Correction factors are used to adjust power and torque measurements to standard atmospheric conditions to provide a more accurate comparison between engines as they are affected by the pressure, humidity, and temperature of ambient air.[19] There exist several standards for this purpose, some described below.

Society of Automotive Engineers [edit]

SAE gross power [edit]
Prior to the 1972 model year, American automakers rated and advertised their engines in brake horsepower (bhp), frequently referred to as SAE gross horsepower, because it was measured in accord with the protocols defined in SAE standards J245 and J1995. As with other brake horsepower test protocols, SAE gross hp was measured using a stock test engine, generally running with few belt-driven accessories and sometimes fitted with long tube (test headers) in lieu of the OEM exhaust manifolds. The atmospheric correction standards for barometric pressure, humidity and temperature for testing were relatively idealistic.

SAE net power [edit]
In the United States, the term bhp fell into disuse in 1971-72, as automakers began to quote power in terms of SAE net horsepower in accord with SAE standard J1349. Like SAE gross and other brake horsepower protocols, SAE Net hp is measured at the engine's crankshaft, and so does not account for transmission losses. However, the SAE net power testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories. This produces ratings in closer alignment with the power produced by the engine as it is actually configured and sold.

SAE standard testing does NOT mean for a crate engine that the testing used is SAE Net-That is only for production car engines as stated now multiple times.

Last word for me on this issue.

 

Finally a last word , not a understanding you are mistaken just a stubborn stomp off i am entitled to my opinion reply .. Your not entitled to your opinion when facts show you have used the wrong information to form that opinion.

Dyno after dyno all over the net shows cars tuned right with a ZZ4 end up with about a 20% loss of HP at the rear wheels .. So somewhere close to 300 rwhp .. No way can you get 300 RWHP with out starting with 350 or so crank horsepower ..

If your "Opinion" it only has 290hp where correct and GM used gross ratings to trick people these dyno tests would be coming back with around 230 RWHP .

 

OK, back to my Blueprint Engine, 383 w/ 405 hp. Does that mean I take away 20% from the 405hp and my number should be 320- 325HP? If it is, then I am happy. Remember, I started out with an L-48 190HP(at the crank?) engine in here.

 

Since most companies are full of it, some where spanked a few years back for advertising higher HP than the car put out.

A very simple way and the way they should it would be to put the car on a certified accurate third party chassis dyno and use RWHP or FWH or both (4 wheel drive ) as the way to rate HP on new cars, this would even the field and no more BS involved.

It is truly the best way to do it, a vehicle may have SAE Net 400 but because of different components involved one car might make 275RWHP and another might make 325RWHP. You would then use the cars weight and have weight to HP number, but you can figure that out yourself.

400HP net engine on a chassis dyno might yield 300RWHp and in a 5000lb truck it ain't gonna be very fast and it would also help people decide on a work truck not necessarily how fast it will go but how much of a load it can carry or pull without stressing out the engine.

Same thing happened a few years back with head flow numbers, higher the numbers the more they can charge. They all got caught over a period of years and you can trust the CFM numbers coming from heads made in North America now(not 100% but close ). I flowed my brand new AFR 227's right out of the box and the were right on the money as to what AFR advertised them to be

 

At the rear wheels expect 20% or so loss from the advertised crank hp.

 

Id expect 22% through a manual gear box, more through an auto.

 

From the research I have done on my 74, the th400 has about a 25-28% loss and the later th350 was around 17-20% from dyno tested revealed in other chevy forums.

 

Wayne dynoed after and before and unless im mistaken maybe hell chime in, with a tk600 he lost 21% or 22%. Ive heard that the 700r4 looses the most, followed by the 400 turbo and 350 turbo coming in top of the autos. When i chassis dynoed the l48, the guy there was convinced that it was a nominal number per transmission and not a percentage.

 

give me a winding mountin road and ill blow u all away with my 335hp motor u all over build ur motors u must have small penises