C4Callum

I'm doing a standard rebuild on my 1990 coupes motor. Would using 1.6 RR make the standard cam similar t a zz4 cam?
ZZ4 engine seems to have around the power I would like and I'm hoping with an Hsr long tube headers and true duels I will have similar performance.

rodj

Not even close
90-91 L98 cam Lift (w/1.5) .413/.428

ZZ4 Lift (w/1.5 ) .470/.510

1.6 rockers on stock 90 cam =.440/.456

Not to mention the much longer duration on the ZZ4 cam ;esp Exh side
ZZ4-208/221 vs 202'/207'on '90

C4Callum

Cheers for the great info.

Bummer. so any idea how much hp the standard cam and 1.6rr would cost me vs thethe ZZ4 cam?

racebum

the biggest benefit to the OE cam is not being forced to tune. the 1990 is speed density which means it uses manifold vacuum. the cam has a big effect on vacuum numbers.

my general advice is to blow right past the zz4 cam and get a zz9, 219 or even XFI cam rather than the zz4 cam. why? well you'll have to tune any of them which is an expense and you'll be buying new springs with any of them, why not get something more powerful if you have to replace all the parts?

there's a good forum link that all new modders should be reading

http://temp.corvetteforum.net/c4/vad...dstrategy.html

rodj

ZZ4 cam is popular because it is often available as a new take out cheap <$ 130 and it works fine but not optimal for TPI.
If paying more , better to get one suited to your combo

Kubs

I tried the ZZ4 in my '90 because I got it for free. It definitely was not optimum. With the cam and a tune I didnt notice a difference. It did wake up quite a bit when I installed headers and duel 3" exhaust, but the only thing it really gained was some mid range power (no dyno based on the butt meter). It lost some low end torque and the TPI choked it off at about 4800-5000 RPM. It would be a better cam if it could spin more.

JackDidley

ZZ4 needs aftermarket heads and intake to get best results. I got my ZZ4 takeout for $85. I was doing heads and intake anyway.

GREGGPENN

Wouldn't you also need guides (headwork) with 1.6 and a ZZcam? (or anything with [even] more lift for that matter.)

C4Callum

For this build fuel economy is as important as hp.

Is there any cam that would suit the Hsr and and retain similar fuel economy to a stock motor.

rodj

Conflicting statement.
Physics 101;
need to burn a certain amount of fuel to make a certain amount of Hp.
More Hp = more fuel.

rodj

You wouldn't bother.
You could buy a cam with the same or better lift (as adding 1.6's ) for the added cost of the 1.6 rockers
and have to do head mods either way

ZZ4 as noted is a quick and dirty perf bump.
Cheap cam , $40 worth of ZZ4 springs and your pick up some.
As I have previously documented ,I ran 13.0X all day (12.98 best ) with a ZZ4 cam in a untouched 100K L98
with big tubes , a saimised base and LT headers (A4 3.07 DR's )

Would it have gone faster with a optimal cam ;probably but was very happy with what I had at that time given $$$ outlay

Calderone

i did the zz4 cam , cool but not impressive, i stayed with 1.5 rockers

C4Callum

personally i dont agree. that would aply if our engines were 100% efficent but there not. the main goal here is to increase the efficency to get extra hp from the same amount of fuel going in under normal operating situations. Physics 102 maybe?

it looks like i will just stick with the standard cam and 1.6 roller rockers. from looking around the net it looks like it will probably only cost me around 20hp. Im ok losing that extra hp but keeping near stock fuel efficency.

Kubs

You just contradicted yourself with you last statement. Engines are at BEST 30-40% efficient. As you increase performance you lose efficiency.

rodj

http://www.epi-eng.com/piston_engine...efficiency.htm

GREGGPENN

Seems like you guys were having trouble following C4Callum.

His statement about sacrificing 20hp has to be by keeping the stock cam vs the ZZ4 cam being suggested.

There's also been a handful of guys touting better mpg after their builds. While some point to the increase in efficiency (VE) as the reason, for cruising range, I'd suspect it's more a result of higher compression. IOW, for the same volume of air/fuel, the charge is compressed tighter and returns a bit more energy.

Increasing VE at any given RPM can create more power and use more fuel. It's also saying the engine becomes more efficient at sucking in air and making more power -- though it also needs more fuel to accomplish the same feat at the same/prior RPM.

Two different issues, really.

C4Callum

Cheers Greg glad some one could keep up. Any one that thinks x gas burnt equals x hp in real world conditions needs to actually study physics.

I understand Your point about extra air requiring extra gas and I'm more than happy to pay for the extra gas when I have my foot planted. I just would really like to have an engine that drives like a stoker till you open it up. That's the main reason I don't really want to mess with the cam. If I could fnd a cam that uses very little more gas in cruising conditions but makes an extra peak 30hp I'd be all over it.

vetteoz

The argument was that on any particular engine;
to make X Hp you need Y fuel.
That relationship does not change unless you improve the VE of a engine

GREGGPENN

In general, more lift gets you that. And lower duration gets the valves closed faster, building more pressure. Ironically, you might need to shorten duration a bit and get it to really steep ramps for improvement in mpg and power. (But,obviously, no one does that!) OTOH, Factorys didn't install steeper ramp cams since it's harder on the valve train (warranty issues). Plus, emissions go up with taller ramps.

Both issues were improved with the cam (base circle) design changes on the LS motors. Head design changes too. Can't snap your fingers and magically improve the gen1 platform.

For the most part, a change in cam -- as proposed here -- isn't going to significantly alter MPGs. Pick the one you want most. If you really want more power, install the bigger one. When your foot is out of it, very little will change in mileage.

As you can see by Calerdone's link, a 1.6 roller set isn't the best idea for a ZZ4 cam. If you stick with the stock cam, maybe you should consider a 1.65 rocker set. 1.7's might work too, but I haven't seen anyone post success with gen1's like they have with LT engines. I have seen 1.65's though.

GREGGPENN

Oh yeah...I would also think everyone here would agree that ANY cam big enough to disappoint (in terms of MPG increase) would be too friggin' big for a TPI. Large duration cams are a bad idea with a TPI (Top-end Performance Inhibitor).





Stay in the 210-218 duration range.