Txdragon

Ok so, I am looking into cams for a complete head revamp and wondering about a few things. Some cams require springs, some only if you're going past stock rev limits. I suppose the extra lift of some cams will take its toll on stock setups and the extra rpm the same. Now.. I don't see why on earth anyone would spend the money on a cam that's going to shift their power band 1500 or more rpm out and NOT swap the springs. Now there's the requirements for the head, what about other concerns? Anything else to concern with by going from a 7200 rpm rev limit to 8000? There's not much info I've found in regards to this, other than making sure the head was in order.. Thanks for the input!

2x0

Txdragon

I figured it was more a blanket, generalized question. But, My current engine. D16Z6. I know the head flow is kinda bland, so PnP is on the list with the works; cam, springs, valves, etc.. I'm leaning toward a comp cam, but was really curious if any other aspects should be considered for higher rpm running.

Txdragon

So valve springs are really the only consideration for higher than stock RPM? D16Z6.

Txdragon

**crickets**

2x0

The stock bottom end is good to 8,000-8,500 RPM. Any more than that and it should be balanced.

So with upgraded springs and retainers, I am thinking you could safely increase your limit to that range if your power band warrants it.

Txdragon

Excellent! That gives me the range that I can work with. With the cam choices, I'd broaden the powerband to around there. Well, between 7500 and 8k. Comp 59300 or Crower 2.

2x0

Yeah fosho!

I forgot how low their stock rev limit was. Cut off at 7200-7400


I been livin' that B series life for too long

Txdragon

yeah, stock rev limit is 7400. Comp 59300 will put my powerband between 5800 to 8k. Crower will put it from 6800 to 8100. Checking out vids though, the 59300 doesn't have the lovely lope you associate with a cammed engine.
I've always been a stickler on function over form, but dangit man!! Although, with my current setup, boost starts at 3500 and I'm peaked by 5300. Comp will make power up to 8k, then plummet. If I'm good to about 8500 without needing to balance my crank, I think my cam choice is pretty clear.

TomCat39

It seems to have been touched on but the bottom end also has to be considered for RPM limits not just the head.

Rod angles play a heavy role in RPM maximum. So basically using trigonometry and algebra you can figure out angles and forces from the stroke and rod length and rpm.

I don't remember what the recommended maximum force is for piston speed changes (acel and decel forces).

As well as materials play a role (aka ARP rod studs etc.)

Txdragon

From what I've read, 8k (on stock internals) is okay for rev on the bottom as long as you've upgraded the valvetrain. Of course, my bottom end is not stock, but my crank has no work done to it. From this info, I read 8.5k is just fine. Anything higher and I'll need to balance the rotating assembly.
with the cam I'm going with, I'll not even try to push it past 8k since that's where the power drops.

TomCat39

Yeah I noticed on the request for motor for bottom end, it went specific.

I was doing the "in general" informational statement that was also requested.

Txdragon

No worries! It was good info either way. You've come through for me a couple times throughout the life of my build! Think the last question I have to throw out there, and I have read through LOTS of stuff, but nothing that answers me question: Should I keep stock valve guides or go with something else? My guides now are in excellent shape. I will not be revving any higher than the 8200 mark, and even THAT won't be too often since power drops after 8k. I'll probably be more around the 7600 range.. Anywho. To guide or not to guide?

TomCat39

It's my understanding that you match the guides to the valves. So if you are sticking to OEM valve, then use OEM guides, if you are switching to specific performance valves then you switch to the guides recommended for those valves.

I believe it's basically material dependant. You can see at Supertech where they recommend a certain kind of guide (material) for a certain type of valve (material) they sell.

It's also my understanding the performance material valve train wears out faster so the head work will have to be done more frequently. Not a problem for race cars but may pose additional stress on street car builds.

TheShodan

iTrader: (14)

I've experienced a bit of both. The valvetrain materials can wear out faster on the head than other components, but it depends upon not only the material of the retainers but the valvespring seat pressures & retainer locks being used. For example, I've had Skunk2 Titanium retainers and valvesprings last over 150,000 miles of street use. but the spring seat pressures were about 70ft-lbs which is like OEM, and used OEM retainer locks. The RPM limit was about 8500rpms anyway.

But I've also had titanium retainers prematurely wear and need more frequent valve adjustments on some Skunk2 AND Supertech valvetrains, using both OEM and Ferrea retainer locks. Some had higher rpms , some lower,but both had higher spring seat pressures of over 90ft-lbs. street/strip builds needed more attention than even street builds. The race builds already change out that equipment each season anyway.

As for the guides. I find that if they aren't broke, don't try to fix them, be they aftermarket or OEM valves. I have GSC and Ferrea valves on OEM steel guides and they work fine. The issue is not just bronze vs. steel, but how those guides are installed. I've had plenty of people with Supertech "Packages" swap out perfectly good guides with bronze ones, only to find out that the machinist installed them completely wrong and micro-fractured the head during installation causing leaks.

I'm not a fan of the bronze guides, but that's simply from my experience with head building. I'd focus on the cleaning of the ports and chambers before worrying about camshafts on a D-series. Those boys need the work that B-series doesn't require for turbocharger utilization. For the turbo D-series builds I've dealt with, I've seen far better results from good port and chamber work over the use of a camshaft. The camshaft was simply the icing on the cake, the port work is where the delicious part of the dessert is in Txdragon's case, here.

TomCat39