| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#41
03-02-2010, 03:33 PM
|
|||
|
|||
Related......
Cliff mentioned a Comp XE284 hyd flat tappet cam "killed" a set of Crower 68405 valve springs. I don't remember how they were set up in that specific application so this is hypotheoritical only, but for a moment let's set aside the actual seat pressure of that spring and look at a potential issue with running it too far away from coil bind and the potential of that situation leading to issues. If set up at it's rated 1.700" installed height and you subtract the 0.930" coil bind dimension it leaves 0.770". Now note that the XE284 cam at a 1.5 rocker ratio has 0.507" valve lift. There is in theory a 0.263" differance ! This situation to me seems like there could be a potential issue if in fact it was similar. This from another site leads to my point: "I would like to hear some opinions on how spring duty cycle/fatigue is affected by running clearance to coil bind." "Actually the closer you get to coil bind is better. The old way of thinking including me was to not over work the spring and have a lot of area before coil bind. Well then we discovered spring surge. . . the wave motion of the coil that continues after the spring has been compressed to its max by the cam lift. This surge can send a rebound wave through the spring assembly and can cause "bad" harmonics. The larger the area between coil bind and max lift the greater the harmonic. The trend now is to minimalize the area between coil bind (stack height) and max lift." Could this situation lead to "killing" a set of valve springs ? Let along the effect it has on the open pressure ! Of interest, a video of a valve spring with valve float: http://www.youtube.com/watch?v=_REQ1PUM0rY&NR=1 Another example with the popular Crane 99893 valve spring. At a 1.850" installed height it is rated with 0.710" max lift with a .060" saftey clearance. Recently I saw that spring set it up at 1.785" for a hyd roller cam. If used with the popular Comp XE281HR (230 at .050) that cam has 0.510" lift, and in theory setting running clearance aside, it would be 0.195" away from coil bind. Is that far enough away to cause potential issue with harmonics ? I have no clue but the fact is worth consideration. Last edited by Steve C.; 03-02-2010 at 04:09 PM. |
|
#42
03-02-2010, 04:55 PM
|
||||
|
||||
|
Quote:
__________________
If you cant drive from gas pump to gas pump across the map, its not a street car. http://s207.photobucket.com/albums/b...hop/?start=100 |
|
#43
03-02-2010, 04:59 PM
|
||||
|
||||
|
Anyone use'n a xe274 run'n 12.0's @ 114 mph in a 3500lb car with a 455/th400/3.42 grs?
__________________
If you cant drive from gas pump to gas pump across the map, its not a street car. http://s207.photobucket.com/albums/b...hop/?start=100 |
|
#44
03-02-2010, 06:01 PM
|
|||
|
|||
|
FWIW
FWIW I have aXE274 in my 66 GTO conv with a 462 maybe low 9 compression with a 4 spd 355 rear and tri-power. It's awesome for wind up. I do have a hesitation off idle and off stopsigns. There after it really runs. I'm not sure what it would be like with an AT. The only other draw back I don't like is it does not like to be driven slow in 1st gear it surges with the lope of the cam.
|
| The Following User Says Thank You to GoGoat For This Useful Post: | ||
|
#45
03-02-2010, 08:14 PM
|
||||
|
||||
|
SC,
Here's the specs: 400 bored 30 over, zero decked. ross pistons with 20CC custom dish, 6.8" rods, 670 heads 70ccs. 9.3 compression. Blueprinted oil pump, hardened shaft, 3/4 groove mains, studded mains. Milodon 7 qt pan and windage tray. Moly rings gapped .022/024. Built in 2004, approx 10K miles and 25 passes. Rotella 15W40 oil, 20 PSI at idle, 50-60 PSI at 3000 RPM. 140 PSI cranking pressure cold. Heads rebuilt with 1pc valves and hardened seats clearanced for 1.6 rockers. 995 springs installed at 1.69". Heads ported to 236/185 CFM at 500 lift. Crower 1.5 stainless rockers. RPM intake, reworked Olds Q-jet, Hooker SC, 3" exhaust. 10" continental Jim Hand converter. TH350 w/transgo 2 kit. Ford 9" with 3.90s. Comp 140 pump with 8AN line 8AN return, 6PSI. MSD ignition. Car is street/strip toy, power drum brakes, no AC. Idles at 850 with 10" vacuum. approx 3600-3700 race weight. Has to idle at 1000 RPM or below, run power brakes and run 93 octane gas. I like a choppy idle, but not mushy off-idle. Has to have decent street manners and make good streetable power. Looking to run mid 12s on motor. May run N20 in future. What kinda cam you recommend for this? The XE274 does pretty well, but I'm always looking for more.
__________________
I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 Last edited by chiphead; 03-02-2010 at 08:19 PM. |
|
#46
03-03-2010, 02:08 AM
|
||||
|
||||
|
Why haven't someone SIMPLY visited thier friendly neighborhood chassis dyno facility and posted some results regarding the XE grinds? How about the builders that use these cams? This could help resolve some of the controversy regarding these grinds .
RoadrageDave, roadcourse engines can also be put on chassis dyno's, like the Nascar guys in this area. |
|
#47
03-03-2010, 02:37 AM
|
||||
|
||||
|
FWIW...
I'm finishing up a 467 stroker/iron head build in which I went with a XE custom grind solid roller cam. Planning on getting it on an engine dyno within a month... (whenever my engine/dyno guy is ready.) Afterwards, I'll gladly post the results. Matt
__________________
Matt 70 GTO 400 4-speed "Turbos make no noise and leave the line like Baby Diarrhea!" - GTOGeorge |
|
#48
03-03-2010, 09:40 AM
|
||||
|
||||
|
The roller lobes have no problems with valve train instability that we have seen anyplace.
Jim Lehart (MrPbody) has used the roller lobes with positive results. I've seen a few of the cars run at tracks where the XE roller cams were being used, and they ran quite well for the combination of parts. Everyone else that I know of that uses them has not seen any power production problems, or a sharp drop in power around 4800-5200rpms. This problem appears to be limited to the flat lobes. You can still get into trouble with the roller cams, as they are quite good at cylinder filling. Chosing one too small can quickly lead to detonation issues. I have ran into this a few times, specifically with the 224/230/110HR grind in 455 builds with mid 9 to 1 ( or higher) compression ratios......FWIW.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
|
#49
03-03-2010, 01:56 PM
|
||||
|
||||
|
Quote:
I don`t see why an engine builder has to have a dyno, otherwise they are not as competent as someone who does anyway. just ask their customers, if they are not happy with the engine performance they will not go back, if they are happy, job done. as long as you agree on what the performance target is beforehand. I hope the OP got an answer to his original question after all these pages. 
__________________
69 Firebird 472, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 10.90 @123 |
|
#50
03-03-2010, 02:43 PM
|
||||
|
||||
|
By post #7 we had it pretty well covered....then the XE camshaft bashing started, guilty on all counts here!.....LOL.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
|
#51
03-03-2010, 05:19 PM
|
|||
|
|||
|
[/QUOTE]You can still get into trouble with the roller cams, as they are quite good at cylinder filling. Chosing one too small can quickly lead to detonation issues. I have ran into this a few times, specifically with the 224/230/110HR grind in 455 builds with mid 9 to 1 ( or higher) compression ratios......FWIW.....Cliff[/QUOTE]
Aaaah, i guess this is why this cam works quite well in my SD455 with stockheads and max 8.5:1 compression...i have measured the performance witha G-tech and it reached a trapspeed of 107,4 mp/h...wich i think is not too bad for a mild build. Power peaks at 5100 rpm....pulls like a tank from idle to 5100 wich is what i wanted since it is streetcar... |
|
#52
03-03-2010, 05:22 PM
|
|||
|
|||
|
PS: Roadrage David, since you are not too far away from me iw ould lend you my G-tech so you could measure your car...but to see at what RPM it makes what HP you would have to visit a dyno. I can´t believe you have not dynoed it yet to fintetune it after obviously spending tons of money on your dreamcar. There should be plenty of dynos in Holland...
|
|
#53
03-03-2010, 05:24 PM
|
|||
|
|||
|
PS: Roadrage David, since you are not too far away from me i would lend you my G-tech so you could measure your car...but to see at what RPM it makes what HP you would have to visit a dyno. I can´t believe you have not dynoed it yet to fintetune it after obviously spending tons of money on your dreamcar. There should be plenty of dynos in Holland...
|
|
#54
03-03-2010, 09:35 PM
|
||||
|
||||
|
Cliff- I would welcome your input as well for a HFT alternative to the XE274, for my setup above....
__________________
I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
|
#55
03-04-2010, 11:14 AM
|
|||
|
|||
|
"I can´t believe you have not dynoed it yet to fintetune it after obviously spending tons of money on your dreamcar."
Picture of Roadrage David's engine discription and a picture of a engine on a dyno in post #24 here....... http://forums.performanceyears.com:8...=387990&page=2 What is missing and the subject of controversey is at what rpm did it make peak power at. |
|
#56
03-04-2010, 12:10 PM
|
||||
|
||||
|
Steve C, If RR Dave was making
Quote:
 For a comparison, here's an article comparing the XE268, XE274, and XE284 in a 454ci BBC. With the XE284, the BBC only made 536HP at (gasp) 5,700RPM!: http://www.corvettefever.com/techart...ting/dyno.html
__________________
T56 Conversion Guide: http://forums.performanceyears.com/f...d.php?t=619532 Part of The Harem:   
|
|
#57
03-04-2010, 12:30 PM
|
|||
|
|||
|
I took all the info I could find on the combo. Input into my Performance Trends computer suggests peak tq at 4600 rpm with 575 ft.lbs. and at 5600 rpm it made 571 hp.
It carries: 5700= 571 5800= 568 5900= 568 6000= 566 My computer is within 3 hp of what he states. With that said, I must add that on most situations my calculator is off on the peak power rpm. Typically as much as 200 rpm and on occasions closer to 300 rpm. I find this when I compare results with known specifications for imput to actual engine dyno sheets. Add 200-300 rpm and it suggest the combo makes peak power at 5800-5900 rpm. And as noted by the suggested computer results with the numbers generated it should rev above 6000+ rpm. But just because we have a motor that is stated to rev or pull past a certian rpm does not mean that it makes peak power that high. |
|
#58
03-04-2010, 12:43 PM
|
|||
|
|||
|
Here is a article some will find of interest:
http://www.carcraft.com/techarticles...fts/index.html They choose three cams with almost identical duration numbers to use as test mules to compare a hyd flat tappet, a hyd roller and a solid roller. Note they choose about the same duration for a hyd flat tappet as the hyd roller, but add additional duration for the solid cam, in this case 8 degrees. But as you can see at the valve after lash the solid roller has the same duration as the hyd flat tappet cam. But as stated note the tremendous velocity the mechanical roller cam can generate throughout the entire lift curve. Of interest, note the base cam is the infamous Comp 284XE hyd flat tappet cam that won't rev up. But here in this short stroke sbc application it goes to 6200 peak rpm with no issues. That said, I think it might be important to note the valvetrain components they used for the XE284 flat tappet cam here. Comp Pro Magnum roller rocker arms, valvesprings with 153 lb seat pressure and with titanium retainers on the springs. As noted the lighter retainers make a big differance in how well the spring controls the valve by reducing the weight of the spring/retainer package. Plus keep in mind this is all revolving around a small block Chevy valvetrain weight, even though the piticular heads in use here have longer, thus heavier valves, it's valvetrain weight is probably lighter than a typical Pontiac. But I don't know that for a fact. But many question the use of 100-115 lb seat pressure to control a Pontiac valvetrain weight with that cam ! And that further makes me want to ask what springs were in use with the these lifter crashing XE284 cammed motors that don't rev up
|
|
#59
03-04-2010, 12:55 PM
|
||||
|
||||
|
"Steve C, If RR Dave was making....blah, blah, blah......"
One pass down the old 1/4 mile track would tell us EXACTLY how much power he is or isn't making? Until then it's just a bunch of dialog on a website, or toilette paper if we were still sending letters or faxes back and forth!.....LOL.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
|
#60
03-04-2010, 01:13 PM
|
|||
|
|||
|
Cliff, but that one pass down the drag strip will not indicate where his motor makes peak power at. That is the only interest I have regarding his combo. That and the spring pressure used
Related and another gold star for Mr P-body ? Engine recipe "D" from Central Virginia Machine Services in Jim Hand's book...... Camshaft: Comp Cams XE274H hyd flat tappet with 1.5 rockers Valve Springs: Comp Cams 150 lbs seat, 300 lbs. open @ mak lift. |
| Reply |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Linear Mode
