bad68coupe said:
Roller cams are definetly NOT for a high RPM application. In high RPM's roller lifters will tend to float your valves. This is why when shops build race motors which will see a lot of high RPM (above 6500) they will never use roller lifters. Take NASCAR for example, their motors are built to hit 10K RPM they use solid flat tappet lifters. Now that may be a NASCAR rule that they use flat tappet lifters but in other applications like Daytona Prototypes this would not be an issue yet they still elect to use the flat lifters. Because of their very high tech use in these two applications I certainly wouldn't call them "old technology" but they certainly have been around longer. But they still have their uses.
To answer your question about when to use them and if they are more efficeint, they are more efficeint and allow for a steeper ramp on your cam. Full roller motors will also run cooler since there is less friction within the motor which causes heat. Not to sound like a commercial but heat will help to break down your oil. Now most of us change our oil on a regular basis so this is not much of an issue.
To sum up a really long discussion about all this, roller motors tend to last longer if you don't abuse them.
Hope that helps and answer your questions.
Sharps-Nut said:
I think it has a great idle (personal prefference of course), but probably not what you are looking for. It sounds lilke there is something going on under the hood, but doesn't sound like a dragster either. I can send you a link to to a dyno video that progresses from idle to WOT. Gives you a good idea of how it sounds sitting at a stoplight...
Scott
I really don't think there is an engine builder in racing that would use a flat tappet if the rules don't require it. Hydraulic rollers are not much help for a mild cam. When rpm and spring pressure get high, there is a definate advantage. I have seen stock flat tappets go over 200K miles enough times to doubt that friction and wear, though present, are what kills motors or even present much friction. To run a HR in a non-roller block will cost plenty as well. For new parts including cam, lifters, springs and push rods, you will be nearing $900 or $1000. Call Comp Cams and get them to help you with what you need.
Just finished my cam install - comp cams XE274H. Here is a video of it running w/ open headers. Sounds pretty mean now. We'll see w/ the mangaflow installed.
http://s65.photobucket.com/albums/h...current=tide015.flv&refPage=&imgAnch=imgAnch1
(this was cold start w/ no choke so it wanted to stall and it was hard since I had to keep the rpms down for the neighbors sake)
This one is w/ a basically stock engine and worn no-name turbo mufflers...
http://s65.photobucket.com/albums/h...rent=Picture069.flv&refPage=&imgAnch=imgAnch2
Trevor
http://s65.photobucket.com/albums/h...current=tide015.flv&refPage=&imgAnch=imgAnch1
(this was cold start w/ no choke so it wanted to stall and it was hard since I had to keep the rpms down for the neighbors sake)
This one is w/ a basically stock engine and worn no-name turbo mufflers...
http://s65.photobucket.com/albums/h...rent=Picture069.flv&refPage=&imgAnch=imgAnch2
Trevor
... one more once it was ready to "idle" (800rpm w/ a manual).
http://s65.photobucket.com/albums/h...current=tide016.flv&refPage=&imgAnch=imgAnch1
P.S. I dont usually keep the boat halfway on the driveway but the tide-surge from yesterdays NorEasterly winds put it there.
Trevor
http://s65.photobucket.com/albums/h...current=tide016.flv&refPage=&imgAnch=imgAnch1
P.S. I dont usually keep the boat halfway on the driveway but the tide-surge from yesterdays NorEasterly winds put it there.
Trevor
I am of the opinion that you should ditch the 289 and get a $100 junkyard special 5.0.
Used GT-40 heads, cobra intake, e-cam.
With 3.73s and a t-5 these motors typically get 17-18 around town and 25ish on the highway. Or stick with the stock cam and run 1.7 rollers . . . slightly better mileage. Put down 260rwhp 290rwtq.
If you want to stick with the 289, I would go with the xe256 if you want to stay comp. Port the heads or find some $500 big valve, screw-in stud 351 D0OE heads on EBAY. It seems like everyone has a set nowadays. You will have to mill those . . .
At any rate, you will need overdrive. Mileage and power do not mix with a c4.
Used GT-40 heads, cobra intake, e-cam.
With 3.73s and a t-5 these motors typically get 17-18 around town and 25ish on the highway. Or stick with the stock cam and run 1.7 rollers . . . slightly better mileage. Put down 260rwhp 290rwtq.
If you want to stick with the 289, I would go with the xe256 if you want to stay comp. Port the heads or find some $500 big valve, screw-in stud 351 D0OE heads on EBAY. It seems like everyone has a set nowadays. You will have to mill those . . .
At any rate, you will need overdrive. Mileage and power do not mix with a c4.