Comparing 3V Blower Cams

Hi Guys.
Speaking of cams. I’ve been running Comp Cams 127350 and eyeballing their 127450. If you are running the 127450 in your blown 3 valve would you please list the valve timing from the cam card?

Just curious why are you switch from the 350's to 450's? I have been running the 350's for years, even running them with the turbo

I don’t have a problem with the 127350 cams and I bet they make great turbo cams. I am opening the engine for inspection and to install a billet crank gear so this would be an opportunity to change cams if I was going too. I’d like to see the intake and exhaust valve timing of the 127450 for comparison. The 127450 could offer a couple hundred rpm higher range and a little more power.

Top card is 127500. The 450 has 4 deg more exhaust duration and 1 more degree lobe separation. These are close and should give you rough idea, I doubt anyone has 450 card to send you. Hope this helps. And the 450 has .005 more exhaust lift
Bottom card is 127400 so disregard

Midlife Crises said:

I don’t have a problem with the 127350 cams and I bet they make great turbo cams. I am opening the engine for inspection and to install a billet crank gear so this would be an opportunity to change cams if I was going too. I’d like to see the intake and exhaust valve timing of the 127450 for comparison. The 127450 could offer a couple hundred rpm higher range and a little more power.

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make sense, if the motor is getting opened up, I was just curious.

The 127450's have 16.5 degrees of overlap @0.050" lift, the 350's have -2 degrees @0.050" lift. The

127350's close the exhaust valve sooner so will have better low RPM torque, the 127450's close the intake later but use the exhaust to scavenge the intake charge to make more peak torque. The extra intake duration and lift will aid in high RPM power.

With long tubes, no worries about the overlap as there is going to be almost no backpressure in the exhaust and with a P/D blower, reversion is almost impossible.

I personally would pick the 127450 but I am not sure I'd bother with replacing the 127350's that are already there.

Thanks guys. Your only confirming what I’ve been thinking. The 127450 has pretty much the max lift that stock ports can use and the added duration and a small amount of overlap should be good for a couple hundred more rpm up top. That’s why I want to see the actual valve timing. Is it worth while? Don’t know. Cams, springs, limiters and a new tune certainly isn’t cheep.

https://mgispeedware.com/camshaft-calculator/

I haven't found one where you can overlay 2 different cams.

That’s a cool simulator and fun to play with. Years ago I used Desktop Dyno to design a cam for a Magnacharged Harley and then had Andrews grind it for me. Fun project and the bike still lives today.

It would be nice if you could enter the duration figures at .200" lift to get an even better idea of the difference of how much the valve is open as the ramp rates of the lobes between the SPR lobes and the VSR lobes is fairly dramatic. For the 127350's vs the 127450's, the duration at .200" lift for the intake is 10 degrees and the exhaust is 7 degrees.

I don’t remember being able to alter ramp rates beyond selecting lifter type in any program I’ve messed with. Sometimes zero lift and 0.050” are both listed.

Comp's camquest was one that I played with years ago.

I'm running 127550's on my tvs car with stock heads and limiters. You hear about driveability issues with these cams but honestly I don't experience any. 5r55s, circle d 3800 stall and 4.10's. These cams make great power. Even at 1/2 throttle, as soon as you hit 4000 rpm it feels like someone got behind you and started pushing

How does the cubic inches of the engine effect the cams say 4.6 vs 5.4?

Oneslow50 said:

How does the cubic inches of the engine effect the cams say 4.6 vs 5.4?

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With a bigger motor, there is more cylinder volume to fill so basically it will need larger duration events to have the same power band.
For example the stock cams on the 2005-2010 mustang GT and the 5.4L F150 were identical, as were the heads. The Mustang reaches its torque peak on a 4.6 at 4500 rpms and the F150 5.4 reaches its torque peak at 3750 rpms.

So would the 127550 need as much gear and stall on a 5.4? I have a 5.8 short block in my f150 with a 6r80, 3.55 gears, 2,500 circle d converter

The added weight of it being a truck and turning (typically) taller & heavier wheels and tires will be the biggest factor here. Without knowing more about the truck or its use, it is tough to comment on it.

Truck is roughly 6,000 pounds rear wheels/tires are about 60 pounds each, tires are 30" tall. L&m 5.8 10:1 compression, rgr stage the 3 head with larger valves, ported edelbrock eforce, 90mm throttle body and mass air, custom grind cams. Made right a 600hp and 595 tq.

With stage 3 RGR heads and that many cubes to fill, I would have thought that they would have selected an intake lobe with more lift to let those heads shine.

How much boost are you running?

What RPM did they take it to on the dyno?