Blown 304 5ltr Cam

[B_rad2723]

G'day all I'm after recommendations on a cam for my 93 VP 304 5ltr, I'm doing a 355ci stroker build with, ported heads "no VN heads", valve train "double row springs", bottom end work, 6-71 short rotor blower & t5 manual conversion if I'm lucky if not t56 conversion. I've sent crow cams an email in regards to this but haven't head back as of yet, the end goal of this build is to retain the 3.08 ratio diff for 1200rpm hwy cruising if possible while putting down good results right threw to 6000rpm & a tuff idle that won't give me grief at low RPM. The use will be as a all rounder tuff streetable day to day cruiser that'll put on a show "when wanted".

Cheers in advance

 

[shane_3800]

Any mild cam that makes power out to 6k will do. You're not really going to need a big cam to get to 6k.
You can get a blower cam but all that will do is take a bit out of the bottom end and shift it to the top which I don't think is ideal tbh as you'll be running a 3.08 diff so you'll want everything down low.
I think that diff would not be ideal with a T56.

 

[Immortality]

Why would a blower cam take a bit out of the bottom end and shift it to the top end? That does not make sense. If you put in a cam with more duration it will move up the torque/power curves (so any cam bigger than a stock cam). A blower cam, much like a stock cam tends to have less overlap that the equivalent n/a cam so a blower cam compared to a n/a cam tends to be more mild.

Cams designed for boost tend to have a wider LSA, cams for n/a applications tend to tighten up the LSA for performance.

1200rpm cruise on the highway? Not likely to happen as the engine just won't be happy at such low revs even if the can with a T56 box, especially not if you want that "tough idle".

 

[Deuce]

As said, not too big on the duration, wider lobe centres, and your focus should be on longer exhaust durations and higher exhaust lifts.
Blower will force air in, but you have to cam it well to get all the burnt gases out.

 

[Pollushon]

As above, the grind you select will need to take into account the components used to achieve the stroke, chamber sizes and the compression ratio. I always recommend speaking to an experience builder once you know what the fundamentals look like. Someone has already done the hard work for you and an experienced builder knows those people

 

[shane_3800]

Why would a blower cam take a bit out of the bottom end and shift it to the top end? That does not make sense. If you put in a cam with more duration it will move up the torque/power curves (so any cam bigger than a stock cam). A blower cam, much like a stock cam tends to have less overlap that the equivalent n/a cam so a blower cam compared to a n/a cam tends to be more mild.

Cams designed for boost tend to have a wider LSA, cams for n/a applications tend to tighten up the LSA for performance.

1200rpm cruise on the highway? Not likely to happen as the engine just won't be happy at such low revs even if the can with a T56 box, especially not if you want that "tough idle".

If you want to hear it from an expert you can watch an episode of tech talk with Richard Holdner when he has Brian Tooley on him self. Brian explains the differences in his cam as he has N/A cams, turbo cams, centrifugal blower cams and PD cams.
Yes BTR only do US engines but the same logic applies to all engines.

The PD cams widen the LSA to weaken the bottom end Richard Holdner has tested LS9 and LSA cams in N/A engines and boosted engines and they are the exact same... Lower end softend and the top end livend up. This is because the PD charger has lot's of low down torque but start to fall over at the top as the boost drops off.
Centifugal chargers however are weak down low but have a rising boost curve so you want the exact opposite cam.
Boost leakage is a myth and has nothing to do with blower cam design before you mention it.

 

[losh1971]

 

[Immortality]

Blah blah blah, Your hero Blah blah blah....

I know how the different forms of FI work, I also have a reasonable understanding of how cams work. Your hero says all cams are turbo cams and yet now BTR have cams for turbo, blower, n/a so what the **** is it?

Wider LSA does not weaken a PD blower down low. A wider LSA ensures no overlap (or minimal overlap) so you don't blow the boost out the exhaust which is what gives good low end torque.

LS9/LSA compared to what?

But because you brought it up.

LS9 cam 211°/230° @ .050" 122.5 LSA
LSA cam 198°/216° @ .050" 122.5 LSA
LS3 cam 204°/211° @ .050 117 LSA
LS1 (early) cam 199°/207° @ .050" 117 LSA
And a nice dyno graph to show the LS9 has a much better low RPM torque curve over the LS3 which has a narrower LSA.

Clearly GM saw reason to widen the lobes on the blower cams.

Mokey see (on youtube), mokey repeat.....

 

[shane_3800]

I don't want to get into an argument.
But the LSA is not wider because of boost leakage that is a total myth. Literally call up BTR I'm sure they will be happy to talk and explain it to you because you obviously have trouble with comprehension.

Any way that is all I will say.

 

[Immortality]

I have trouble comprehending all your double speak and flip flops.

The numbers and power curves above show it all.