technical thread discussing the ZL1, potential expansion projects, capabilities of...

[WheelmanSS]

Originally Posted by adamgl

Ok, how much can or should you turn up the boost before you need to fully forge the motor?

I am sure you're going to get a lot of subjective answers on this depending on who you talk to and their experience with boost.

The LSA being what I call a "LS9-lite", has the smaller 1.9L blower and a slightly lower CR at 9.1.

Personally, I'm not super comfortable with that CR area. I'm sure in near-stock applications, it provides more forgiveness at slightly higher boost levels with 93 octane, and less need for adjustments to timing retard. However,

To say, "at X boost, you will need forged engine components" is difficult and matter of opinion to a certain degree. But dished pistons, and you would probably go forged, would help drop that CR to the 8.5 to 8.8 range. This is where I would get a bit more comfortable with higher boost. Also, some work to the heads to expand the combustion chamber will also help lower the CR.

At this point, all of this is a matter of personal comfort. Some people will up the boost with little more than higher octane. Tuning plays a big part from a security aspect, but to really get big boost numbers I think that the static CR is going to have to be in the LOW 8.X range to really get crazy with higher boost.

[WheelmanSS]

Also, just talked to one of my buddies with a CTS-V. He is telling me he picked up right around 75 RWHP with a switch to the 9.5" lower pulley and dyno tune. Not saying this is a direct correlation to what the ZL1 can gain, but at least gives an idea.

[1BADZL1]

Yes, the lower CR the better...
as the octane rating of gasoline decreases and the demand for more horsepower increase, (we always want more HP right?) there is more of a possibility for detonation. Forged pistons made for blown systems are highly recommended. Also using 8.5 to 9.1 compression ratio and less blower boost will keep the engine cooler. When you run a lower compression engine and raise the boost levels, this elevates the temperature of the air charge to your engine, (remember the more colder air coming in the better) requiring you to buy higher octane gasoline (or make your own octane as some do) to suppress detonation.
Gonna be fun to have a factory built supercharged camaro for a change.. and one more thing.. Don't run just regular gas...
I bet it will be sure to have detonation issues if you do!

[adamgl]

Originally Posted by 1BADZL1

Where we at from factory 14 #'s?

Good question, I don't know.. Sucks I can't even get 93 octane anywhere close. Only have 91.

[tfghung]

Originally Posted by WheelmanSS

Also, just talked to one of my buddies with a CTS-V. He is telling me he picked up right around 75 RWHP with a switch to the 9.5" lower pulley and dyno tune. Not saying this is a direct correlation to what the ZL1 can gain, but at least gives an idea.

I am so ignorant, but what does the lower pulley control? Does it spin the supercharger faster?

[KKreme15]

http://camaro5.com/forums/forumdisplay.php?f=145

[WheelmanSS]

Originally Posted by tfghung

I am so ignorant, but what does the lower pulley control? Does it spin the supercharger faster?

The pulley size impacts the supercharger drive ratio. So yes, by increasing this ratio, you spin the supercharger faster thus creating more air and creating more boost.

Think of the pulleys in a similar way to rear end gears. When you change the ratio on your rear end, you change the characteristics of the cars performance. Higher gear ratio, more lower end drive (car gets up and moves faster, but lower top speed potential). Lower gear ratio, more higher end drive (car builds speed at a different rate, but can reach higher top end speed).

[brada]

This is a great topic.!
I'm also wondering what the factory boost would be.. i assume somewhere around 7lbs because of Engineered safety margins?? im sure you can run higher boost by changing the pulley ratio, but the inverse side of that is that you cant always have you foot in it.. Currently they are tested at 100% duty cycles, but with increased boost,.. one would probably scale back the abuse if staying with stock internals??
I wonder if the the new GT500 is built to be run all out all the time?.. is the ford setup pushed to its max from the factory?

[WheelmanSS]

Originally Posted by brada

.. Currently they are tested at 100% duty cycles, but with increased boost,..

huh? Can you clarify that?

Duty cycles generally refers to injector output capability. There is no way the stock injectors are running at 100% duty cycle. That would be like playing russian roulette... and on a stock, factory car, that would be russian roulette with 5 of 6 chambers holding a bullet.

[adamgl]

Originally Posted by brada

This is a great topic.!
I'm also wondering what the factory boost would be.. i assume somewhere around 7lbs because of Engineered safety margins?? im sure you can run higher boost by changing the pulley ratio, but the inverse side of that is that you cant always have you foot in it.. Currently they are tested at 100% duty cycles, but with increased boost,.. one would probably scale back the abuse if staying with stock internals??
I wonder if the the new GT500 is built to be run all out all the time?.. is the ford setup pushed to its max from the factory?

Originally Posted by WheelmanSS

huh? Can you clarify that?

Duty cycles generally refers to injector output capability. There is no way the stock injectors are running at 100% duty cycle. That would be like playing russian roulette... and on a stock, factory car, that would be russian roulette with 5 of 6 chambers holding a bullet.

I think he meant you can drive the factory car hard at a road course for long time and be fine. Extreme example is the 24 hour Nurburgring test. But at higher boost you could have problems earlier if you are driving all out.

[SSmoked]

^FYI they didnt do the 24 hour test at the 'ring it was at there proving grounds.

Boost is at a fixed output (+/- 2psi pending airtemp), via the pully. more boost = more heat. thing with blown motors is heat soak so with more boost comes the need for more cooling mods ( heat exhacnger, meth....), especially on the road course where the car is full out for more than 12 seconds. It will be interesting to see, i think 95% of ZL1 owners wont have the car on the road course where its meant to be.

[brada]

yes.. my bad.
from what i've been told, the fisrt few development engines GM ran.. (bench tested) on 100% duty cycle.
-first test , they were run to 6000 rpm for an hour straight..
-second test, from idle to WOT repeatedly for an hour
-third tested , roll on throttle acceleration from 2200 rpm to wide open.

the point being that they assume it very unlikely that an average joe will run the car at 6000 rpm for an hour.. that being thier worst case scenario.
So the mind set was , build engines to worst case scenario and tune down for street reliability.. vs.. build to nornal street use and then tune them to the max limit.
It seem GM has left lots of room for modification and still stay relatively safe and reliable.

[WheelmanSS]

Originally Posted by brada

yes.. my bad.
from what i've been told, the fisrt few development engines GM ran.. (bench tested) on 100% duty cycle.
-first test , they were run to 6000 rpm for an hour straight..
-second test, from idle to WOT repeatedly for an hour
-third tested , roll on throttle acceleration from 2200 rpm to wide open.

the point being that they assume it very unlikely that an average joe will run the car at 6000 rpm for an hour.. that being thier worst case scenario.
So the mind set was , build engines to worst case scenario and tune down for street reliability.. vs.. build to nornal street use and then tune them to the max limit.
It seem GM has left lots of room for modification and still stay relatively safe and reliable.

Oh i see. You're referring to tuning and AFR then?

This is a staple for almost all cars that are FI based out of the box, for the most part.

That is why we saw serious gains on the 03 Cobra with just a pulley and a tune. If you want to go apples-for-apples, the same thing with gaining 75-ish HP on the CTS-V with a pulley and tune.

GM is also using (by my definition) a smaller blower on the LSA with the 1.9L. And given that the CR is in the 9.1 range, it allows enough boost to supplement the power without relying on it as the base of the platform.

[brada]

Originally Posted by WheelmanSS

Oh i see. You're referring to tuning and AFR then?

This is a staple for almost all cars that are FI based out of the box, for the most part.

That is why we saw serious gains on the 03 Cobra with just a pulley and a tune. If you want to go apples-for-apples, the same thing with gaining 75-ish HP on the CTS-V with a pulley and tune.

GM is also using (by my definition) a smaller blower on the LSA with the 1.9L. And given that the CR is in the 9.1 range, it allows enough boost to supplement the power without relying on it as the base of the platform.

..
Its gonna be interesting to see how far these FI motors can be pushed..