[BlaqWhole]

Originally Posted by Can'tHave2MuchHP

Well, I'm not the best with wording and explaining and it's rathe late at night but I'll give a quick rundown...

Boost = Pressure. Obviously. It also means heat. Too much of either is catastrophic. As little as possible of either is ideal.

A cam opens and closes valves that control air. There's a ridiculous amount of R&D that goes into cam development, and even now, no one knows the "BEST WAY" to make a cam that's perfect in any given situation. But in a nutshell, a cam helps a FI engine to BREATH. To suck in more, and to blow more out. Blowing a lot of boost to stock Cam cars results in too much back pressure and very high IATs.

On the LSA, you can run about 12-13 pounds of boost before the stock cam is a huge limiting factor and your temperatures will be off the charts.

On the LS9, it's roughly the same.

On the LT4, it's past the point of a 2.31 upper, or roughly 12 pounds again.

Adding anything that reduces back pressure, like Headers and ported Heads, will help but specifically the big one is a Cam. Less pressure, less heat, more intake...more power.

A proper cam with a professional install is nothing, well worth it, and a part of the game/nature of the beast if you want to push 700, 800, or 1000 HP on an LT4 (Or LS/LT anything really).

Stages of mods (Very few of these can be done out of order):
Intake
Headers
Pulley
Cam
More Pulley (Must be done after Cam swap)
Heads
Ported Blower (Can be done at any stage)
E85 (Can be done at any stage, though much more beneficial after 650 RWHP+)
Meth Injection (Can be done at any stage, necessary after a certain level, more beneficial at bigger power)


As far as Hellcats....Completely different animal with different designs and purposes. I've gone through, and you've seen it, the rants on the Hellcats making easy power as well as being 50-100 HP underrated. It's no question that they're the stock, bolt on, and max effort king. They can make 1000 RWHP on a Pulley, E85, Intake, and a 150 shot. We'd have to be running a different blower or a max effort setup (Heads/Cam/Meth/E85/FBO) and a 200+ shot of Nitrous (RIP engine).

A blower swap on an other wise stock LT4 is a good option, just don't expect it to make more than a intake, pulley, tune LT4 would. Once you go to push past that number, you'll need a cam anyways. Safe to say that I would not recommend messing with a different blower unless you're OK with a monster (And the good and the bad that comes with it) and are ready to bust out some cash, and CAMMING your car.

True. And you explained it the way I would. I know the HC is different. But I'm just expressing that I don't think our stock cams are all that bad and that I think these engines are inhibited mainly by the blower. And I would do a blower swap before pulling the cam out. I mean, OP is already at 650 with his bolt-ons and extra boost and he is probably just about pushing the limits of that blower. If he had even a 2.3 liter TVS I think he would be up closer to what HCs make with similar bolt-ons.

Originally Posted by djfury05

Trust me I was under the same impression on the blower and even more so the fuel until I asked a few professional shops who've done hundreds of different combos on the Z06's and now ZL1's. It all boils down to the stock cam needing replaced to make any RELIABLE power after 700rwhp. I'll take their advice based on results over speculation.

I was not criticizing your decision and I certainly would not tell you to take my word over a professional's word. I stopped doing that dance a long time ago. A lot of these shops are not as good as people think...but debating that is a futile effort. I would say tho, always be wary when someone tells you that you need something and they just happen to sell it. But anyway, I'm always a bit skeptical about cam swaps. But if you have a shop that you feel comfortable with and that you feel is reliable and can give you a great deal then what do you have to lose? I would say go for it. But if you do then you might as well throw a better blower on top too.

[djfury05]

Originally Posted by BlaqWhole

I was not criticizing your decision and I certainly would not tell you to take my word over a professional's word. I stopped doing that dance a long time ago. A lot of these shops are not as good as people think...but debating that is a futile effort. I would say tho, always be wary when someone tells you that you need something and they just happen to sell it. But anyway, I'm always a bit skeptical about cam swaps. But if you have a shop that you feel comfortable with and that you feel is reliable and can give you a great deal then what do you have to lose? I would say go for it. But if you do then you might as well throw a better blower on top too.

No offense taken and completely agree on shops telling you that you "need" something and they'll be happy to sell it to you.

Reason I wanted to stay stock heads/cam is because I hate paying for labor and I'll be doing all the work myself. With all the builds I've done I've never replaced a cam lol. One shop told me that the engine should be pulled to make it easier. So it's intimidating at this point and I haven't found hardly any how to guides on it. I know I can do it myself I just have to work up the confidence and get through the unknowns of the LT4 which right now are a lot to me since all I've dealt with has been LS up until this point.

Additionally since the heads have to come off for deleting the AFM lifters etc then I might as well have the heads CNC'ed and I don't see hardly any programs for them yet and those that are available aren't that great because its a lackluster casting to begin with.

[BlueSteel07]

Why does the LT4 require heads/Cam when making lots of power and the Hellcat doesn't? Are their heads and cam better or is it due to something else? I guess I'm just used to forged DOHC motors (03 Cobra). Just bolt on a bigger blower with supporting mods. No need to open up the engine.

[Can'tHave2MuchHP]

Originally Posted by BlueSteel07

Why does the LT4 require heads/Cam when making lots of power and the Hellcat doesn't? Are their heads and cam better or is it due to something else? I guess I'm just used to forged DOHC motors (03 Cobra). Just bolt on a bigger blower with supporting mods. No need to open up the engine.

DOHC.

[BlueSteel07]

Originally Posted by Can'tHave2MuchHP

DOHC.

But why doesn't the Hellcat need a cam and the LT4 does? A shop slapped a 4.5L Whipple on a Hellcat and it made 1,000 rwhp without opening the engine. Seems like all the procharged LT4 builds need a cam and heads. Why is that? I've heard the words Fuel lobe on the Cam but never really understood that. Does the LT4 need a cam due to fueling? I guess I just don't understand it.

[djfury05]

Originally Posted by BlueSteel07

But why doesn't the Hellcat need a cam and the LT4 does? A shop slapped a 4.5L Whipple on a Hellcat and it made 1,000 rwhp without opening the engine. Seems like all the procharged LT4 builds need a cam and heads. Why is that? I've heard the words Fuel lobe on the Cam but never really understood that. Does the LT4 need a cam due to fueling? I guess I just don't understand it.

Go back and re-read post #27 in this thread. Its already laid out. The cam will not allow the engine to breathe enough after a certain point. Simple as that. And clearly the Hellcat has more room and much better flowing heads out of the box 295cfm vs 340cfm.

[BlaqWhole]

Originally Posted by BlueSteel07

But why doesn't the Hellcat need a cam and the LT4 does? A shop slapped a 4.5L Whipple on a Hellcat and it made 1,000 rwhp without opening the engine. Seems like all the procharged LT4 builds need a cam and heads. Why is that? I've heard the words Fuel lobe on the Cam but never really understood that. Does the LT4 need a cam due to fueling? I guess I just don't understand it.

There is great info on this, but I am not fully convinced that we do need a cam. I think the blower is the limiting factor. I mean, a 1.7 liter TVS blower is not really rocking people's world. Even the 4.6 2V Mustang guys didn't like that size blower even with a KB twin screw, lol!! So far the ZL1 is relatively new compared to the HC so there isn't too much info out there. But until there are more comparisons and more combos out there I would hesitate to throw a cam in mine. People did that with the 5th Gen...throwing cams in. And I remember all the cam-related failure threads I saw. So I say give it time. Don't be too hasty to open that engine up. Eventually we'll have more aftermarket choices and will really see what we can do with these cars.

[djfury05]

Originally Posted by BlaqWhole

There is great info on this, but I am not fully convinced that we do need a cam. I think the blower is the limiting factor. I mean, a 1.7 liter TVS blower is not really rocking people's world. Even the 4.6 2V Mustang guys didn't like that size blower even with a KB twin screw, lol!! So far the ZL1 is relatively new compared to the HC so there isn't too much info out there. But until there are more comparisons and more combos out there I would hesitate to throw a cam in mine. People did that with the 5th Gen...throwing cams in. And I remember all the cam-related failure threads I saw. So I say give it time. Don't be too hasty to open that engine up. Eventually we'll have more aftermarket choices and will really see what we can do with these cars.

The ZL1 may be new, but the LT4 certainly is not. Get the Whipple and leave stock cam in and let us know how it goes. I don't like being the guinea pig lol.

[Can'tHave2MuchHP]

Not sure what some people don't understand here...The cam NEEDS to go above 700-720 RWHP *OR THERE ABOUTS*. You can be "Not convinced we need a cam swap, lol!!" all you want, but seriously, you must be knew to the LS and now LT performance world or something because I've never really ran into someone who doesn't believe in a cam swap for an engine. Opening up the engine is really a stupid way to sway it, reminds me of a doctor's scare tactic...You pull the front assembly off the engine (10 bolts?) pull a chain and gear, yank out a knobby stick and put another one in. Experienced people and experienced shops can do it as good as GM. No issues, no questions asked. If you make a good choice in cams, you'll still have drivability, gas mileage, and you'll add what the engine needs: AIRFLOW & FUEL....And you'll get some good sound too.

And yes, of course the 1.7L blower is a limiter. A big one. But it only matters once you're actually PUSHING that stock blower that you will see how much more the BIGGER blowers make.

So like I said, don't let me convince you, go put a Whipple or ProCharger on it without doing Heads/Cam and pulley the shit out of it to make it make 700-800 RWHP. First off, you'll hit a power wall, a heat wall, and you won't be able to get enough fuel in it with the stock fuel lobe.

Notice a swap on a otherwise stock car does hardly nothing. Same results can be achieved with an upper pulley and intake on the stock 1.7L.

Weapon X: http://www.ctsvowners.com/forum/152-...o-results.html

Now on the other hand, putting that blower on a cammed LT4 (Whipple 2.9) results in MUCH more impressive results:

https://www.corvetteforum.com/forums...ple-2-9-a.html

Both builds ran about the same boost: "14psi and ended around 16psi" "15.5 PSI". Yet 300 HP separates them. Hmmm?

[Infern0]

Originally Posted by BlaqWhole

There is great info on this, but I am not fully convinced that we do need a cam. I think the blower is the limiting factor.

Originally Posted by Can'tHave2MuchHP

Not sure what some people don't understand here...The cam NEEDS to go above 700-720 RWHP *OR THERE ABOUTS*.

And yes, of course the 1.7L blower is a limiter. A big one. But it only matters once you're actually PUSHING that stock blower that you will see how much more the BIGGER blowers make.

Can'tHave2MuchHP thank for confirming. It didn't seem to be the limiter here at only 12lbs.

If I recall, WeaponX or another builder, can't recall, did one that was up around 18lbs...in that neighborhood it seems like it is the limiting factor. It's reached its point of efficacy.

Do I understand correctly?

[Infern0]

Originally Posted by Can'tHave2MuchHP

Well, I'm not the best with wording and explaining and it's rathe late at night but I'll give a quick rundown...

Boost = Pressure. Obviously. It also means heat. Too much of either is catastrophic. As little as possible of either is ideal.

A cam opens and closes valves that control air. There's a ridiculous amount of R&D that goes into cam development, and even now, no one knows the "BEST WAY" to make a cam that's perfect in any given situation. But in a nutshell, a cam helps a FI engine to BREATH. To suck in more, and to blow more out. Blowing a lot of boost to stock Cam cars results in too much back pressure and very high IATs.

On the LSA, you can run about 12-13 pounds of boost before the stock cam is a huge limiting factor and your temperatures will be off the charts.

On the LS9, it's roughly the same.

On the LT4, it's past the point of a 2.31 upper, or roughly 12 pounds again.

Adding anything that reduces back pressure, like Headers and ported Heads, will help but specifically the big one is a Cam. Less pressure, less heat, more intake...more power.

A proper cam with a professional install is nothing, well worth it, and a part of the game/nature of the beast if you want to push 700, 800, or 1000 HP on an LT4 (Or LS/LT anything really).

Stages of mods (Very few of these can be done out of order):
Intake
Headers
Pulley
Cam
More Pulley (Must be done after Cam swap)
Heads
Ported Blower (Can be done at any stage)
E85 (Can be done at any stage, though much more beneficial after 650 RWHP+)
Meth Injection (Can be done at any stage, necessary after a certain level, more beneficial at bigger power)


As far as Hellcats....Completely different animal with different designs and purposes. I've gone through, and you've seen it, the rants on the Hellcats making easy power as well as being 50-100 HP underrated. It's no question that they're the stock, bolt on, and max effort king. They can make 1000 RWHP on a Pulley, E85, Intake, and a 150 shot. We'd have to be running a different blower or a max effort setup (Heads/Cam/Meth/E85/FBO) and a 200+ shot of Nitrous (RIP engine).

A blower swap on an other wise stock LT4 is a good option, just don't expect it to make more than a intake, pulley, tune LT4 would. Once you go to push past that number, you'll need a cam anyways. Safe to say that I would not recommend messing with a different blower unless you're OK with a monster (And the good and the bad that comes with it) and are ready to bust out some cash, and CAMMING your car.

This should be framed.

[laynlo15]

I would choose the Magnuson, its proven and its gonna make pretty much the same hp/torque as the Whipple. Haven't seen one whipple LT1/LT4 go down the track, not even a time slip. Magnuson has already went 9.92@140, no internal mods, no headers, etc. It does have the upgraded lift pump and high pressure pump and Drag Pack.

[Robbs1le]

The real reason you need a cam over 700 is you run out of fuel and the high pressure side in the lt4 is cam driven so you need a bigger fuel lobe. Jms is a great shop I drive from Oklahoma to have them do all of my work!

[djfury05]

Originally Posted by laynlo15

I would choose the Magnuson, its proven and its gonna make pretty much the same hp/torque as the Whipple. Haven't seen one whipple LT1/LT4 go down the track, not even a time slip. Magnuson has already went 9.92@140, no internal mods, no headers, etc. It does have the upgraded lift pump and high pressure pump and Drag Pack.

I don't think your signature could make it anymore obvious you're all about Magnuson.