Cams/heads, or go straight for blower?

[RED09GT]

In a nutshell, the valve timing requirements are different when your pounding air in the engine at two or three atmospheres. It is not as important to open the intake valve early and the exhaust can be left closed a little bit longer. Valve overlap will run rough and waste fuel and air out the exhaust until the engine is wound up enough to overcome it. There are several blower cams on the market that open the intake at or after TDC. You don’t find that characteristic in NA cams. So any old cam doesn’t make a blower cam.

Lots of websites with lots of advertisers that agree with you but there is a lot more to it.
Does opening the intake valve earlier prevent a blower car from making power? Or will it make more power if you increase the duration that the intake valve is open?
All else being equal, I won't disagree that you will have more lope with the average N/A cam and you will make more boost with a blower cam but is boost a measure of airflow or resistance?
If an engine is making less boost, does that mean it is making less power or is it less able to consume all the air in the intake tract?
Would you rather make 600hp with 14 lbs of boost or with 12 lbs?

 

[Dino Dino Bambino]

"Every cam is a blower cam!"

Er, no.
Blower cams need reduced valve overlap (wider LSA) to minimize exhaust gas reversion and also need a longer exhaust valve opening duration. The stock cams are actually pretty good blower cams but the short intake valve opening duration limits their potential. OTOH, the Hot Rod cams aren't good blower cams due to their narrow LSA and long valve overlap.

 

[RED09GT]

BruceH's car did pretty damn well with Hot Rods and boost. It was missing all the issues that everyone thought it would have as well.

But yeah, I agree with you, blower cams make shit poor N/A cams

Er, no.
Blower cams need reduced valve overlap (wider LSA) to minimize exhaust gas reversion and also need a longer exhaust valve opening duration. The stock cams are actually pretty good blower cams but the short intake valve opening duration limits their potential. OTOH, the Hot Rod cams aren't good blower cams due to their narrow LSA and long valve overlap.

 

[Midlife Crises]

I agree there is a lot more to it. The early opening intake valve does very little by itself but with a late closing exhaust the resulting overlap will loose fresh air out the exhaust. How much overlap can be tolerated depends on how the engine will be operated. It’s easy to make a case for special cams for turbocharged engines when you consider they operate with higher exhaust pressures than NA or blower engines. Cams are not universal.

 

[tjm73]

If any engine has a nice power delivery and you add boost (say 7-8psi) is it not going to make more power? Is it not going to just amplify what it already makes? I've yet to see a cam magically make an other wise engine make monumentally more power. What the engine makes naturally aspirated is multiplied by the boost delivered at every rpm.

Boost can change the curve by the way it delivers it's boost curve. That's true. But that's not the cam.

 

[JEWC_Motorsports]

 

[Badd GT]

having done both 2 my car, skip the NA mods and go straight to the supercharger

 

[Pentalab]

It's a mixed bag really. Mine is just a street car. 90% of the time the blower is never used. I can get my right foot into it just enough, to keep the boost gauge either at zero boost, or just a tiny bit less than that.... and it pulls good and hard. Instead of cams, or a smaller pulley, I installed the jba ceramic coated LT's + catted H....and then another retune for 94 octane. The LT's, twin 62mm tb, alum DSS-DS, 94 tune, new brisk plugs, 7 bar upper grille, tru-trac,watts link, 305mm rears / 285mm fronts, lowered suspension, roush suspension package with stiffer front and back sway bars, etc, all combined, make for a reasonably good street car. Toss in the 1.5 krpm oem stall converter and oem automatic..and small blower, it's good enough for my application. Mash the gas, get into boost, drop down some gears, and it's effortless passing anything and everything on the street/hwy.

It really all depends on the final application. The last thing I want is to lose low to midrange tq.

 

[eighty6gt]

I love my comp springs required no phaser modification cams. They sound great and the car absolutely TEARS up top compared to before. It's all about that rice for me.

 

[LarryJM]

The kind of blowers I like are not cheap. Maybe $8000.

 

[eighty6gt]

@Drunkenturtles I would not add cams to a 5.0. I have a 4.6 and got these 2x cams used from Jim Jr. @ JDM "Engineering."

Larry what is the difference between a 8k blower and a 4k DOB setup?

https://www.departmentofboost.com/product/3v-r-spec-supercharger-kit/

man, dob can go a long way. Polish supercharger! Doskonały!

 

[JEWC_Motorsports]

@Drunkenturtles

https://www.departmentofboost.com/product/3v-r-spec-supercharger-kit/

man, dob can go a long way. Polish supercharger! Doskonały!

Thats 11k not 4k

 

[dark steed]

Thats 11k not 4k

$11.5k if you polish it!


Sent from my iPhone using Tapatalk

 

[eighty6gt]

Thats 11k not 4k

Right, I found that going looking for the 4k models. I had answered my own question.

 

[eighty6gt]

$11.5k if you polish it!


Sent from my iPhone using Tapatalk

oh, POLISH.

 

[JEWC_Motorsports]

The Edelbrock for my car was only 5k, what do i know about that expensive shit.

 

[Midlife Crises]

Right, I found that going looking for the 4k models. I had answered my own question.

Exactly what I found when I has looking for a blower package. By the time you assemble a kit with most of the good stuff that is available at the time, DOB packages cost the same as everybody else.

 

[LarryJM]

I did have a Paxton on my 89 GT. That was about $3000. It was a low pressure system. I like it because you could operate it like an air conditioner. I will see if I can find a picture of it.

 

[LarryJM]

Old School Paxton. A low pressure system good enough for 13:80's.

 

[RED09GT]

Exactly what I found when I has looking for a blower package. By the time you assemble a kit with most of the good stuff that is available at the time, DOB packages cost the same as everybody else.

Especially if you are not in the lower 48 states. I looked into going this route and realized it was not worth the effort and the logistical challenges.