little info

5.9 had a cam change in 98

 

A 5.9 has a cam with .410 lift with the stock rockers.
A 5.2 has a cam with .432 lift with the stock rockers.

If you take out the rocker lift you get:

360ci's cam .410/1.6= .256 lift from the cam lobe alone.
318ci's cam .432/1.6= .270 lift from the cam lobe alone.

You can then multiply each lobe by the 1.7 rocker ratio to get the increase in lift.

You get further gains when you couple them with heads that don't peak out at .400 lift like the stockers. See this link for a comparison chart of heads.

 

Yeah I agree, definitely smoother all around just really noticeable in those higher RPMs, I like being able to rev my engines and not have them sound/feel like they're going to break apart.

 

There have been a couple of times when I thought for sure my engine was going to start flying apart like something out of a cartoon as the rpms approached 5k. With the HSRRs, I just don't get that same experience.

 

my 5.9 likes to shift into 2nd gear at 6K RPM when at WOT. That was after the 1.7s and SCT tune.

I didn't even notice engine noise, but my heart skipped a beat when I looked at the tach to see the RPMs at the 1-2 shift.

But, my truck has only 50K on it and it has had synthetic oil changes its whole life every 3K RELIGIOUSLY. I have to give credit to Mobil 1 as well!

 

Are you running 6K on stock springs and pushrods? If so, you're way braver than I.

 

thank you to everyone who has replied. got great info from everyone one.. just one more question has anyone did a cam change from the 5.2 into the 5.9? cause it has more lift and with that cam with 1.7s i think it would be alittle faster over a regular 5.9 with just 1.7s!

 

I wish I could, my valves float at 5500.

 

The usefulness of a cam is not in the lift alone, duration, LSA, lobe profile, and lift all play a factor in how a cam performs.

If Chrysler could have made a cam that worked equally well for both engines, I think they'd have stuck with one design.

 

I can't find the dyno sheets to back up my claim as this was several year ago, but I had a baseline dyno on my RT prior to installing the HS 1.7 RR's and then dynoed it again after the install. Show a 10hp/10tq gain at the rear wheels. Definitely the best bang for the buck mod to my engine out of any that has been done.

I got a smoother idle, engine seems to rev with a lot less effort and a little mpg increase. I highly recommend them for any 5.2 or 5.9 and especially for the 3.9 V6.