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#81
01-22-2017, 12:58 AM
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"I have a ( close to XE lobes ) small XTQ lobe with cool face solids in a 462 with 6X-8 heads 236/242 @.050 on a 112 L/C with a 2.73 gear Auto with a cheap 500 over stock stall.. At the time of choice it was my daily driver so I went conservative as one would expect.. Stupid torque just off idle not sure where it tops out at RPM wise because this car has no tach."
I installed a custom ground XTQ lobed solid flat tappet cam from Comp in my last 455 for back to back dyno testing against the Crower 60919 camshaft. The spec on the XTQ lobed camshaft were 240/248 @ .050" on a 112 LSA. Despite having more .050" duration and a LOT more lift, the engine LOST 10hp/22ft lbs peak torque, and peak HP fell clear back to 5200rpms from 5600rpm's. Average power was way down as well. The only thing the custom ground cam did was idle better, making a solid 2" improvement in vacuum at 750rpm's. Not liking the results I ordered a custom ground HR cam from Comp with 230/242/112 specs using .361" lobes. It made 3 more HP and 4 ft lbs torque improvement over the Crower 60919 cam, and it also idled with 1.5" more vacuum. Even so peak HP fell back to 5400rpm's from 5600rpms, which surprised me a bit until you look at how big the 60919 cam really is. I left the HR cam in place and backed up the numbers at the track. Of course it wasn't on the same day, but average ET and MPH improved more than the dyno numbers showed by about .15 seconds and 2 mph. Best run ever with the 60919 cam was 11.64 at 116mph. The HR cam went a best of 11.52 @ 118mph, so there is something to be said for the roller lobes allowing the engine to rev quicker and the car gets there sooner. The very best part of the testing in my eyes is that we can make nearly the power of a very well chosen HR cam with a flat camshaft at much less cost by using high ratio rockers and Rhoads lifters.......Cliff
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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), |
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#82
01-22-2017, 01:04 AM
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#83
01-22-2017, 05:52 AM
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I am NOT brand specific with camshafts or anything else.
We dyno and track test to find out what works the best. The cam currently in my engine is from Comp, and all of our custom ground HR cams are Comp, we even have quite a few custom ground solid roller cams in use that they did for us......Cliff
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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), |
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#84
01-22-2017, 07:47 AM
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Hey cliff
Im thinking maybe ditching the dual quad and using a qjet. Just stripped a 79 qjet while reading ur book. Wouldnt mind trying to mod the carb myself. Would you go recipe 1 or 2 in ur book? Thanks |
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#85
01-22-2017, 08:14 AM
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I will need the carb part number and other details. PM me or send an email to: cliffshp@embarqmail.com.....Cliff
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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), |
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#86
01-22-2017, 08:26 AM
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On Cliff's XTQ result, that cam did EXACTLY what it should have.
Intake 269 adv 240 @ .050 Exhaust 277 adv 248 @ .050 112 LSA - tallies to 49 degrees overlap for 462 displacement. 108 LSA would have produced more power across the range and a bit higher RPM. Here is an image snippet that was "Google'd" up a few years ago (Vizard BBC book). What does it say about necessary overlap? Not a surprise. A much higher level tool I have agrees 100% on all counts. Different math source but same RPM and duration 269.5 suggesting 108 LSA. I recall Cliff posted the guys were scratching their heads, butts and about anything else in confusion. |
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#87
01-22-2017, 09:09 AM
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WAY back when I did that testing folks quickly came out from under their rocks and slammed the test criteria and the results telling us that we didn't choose the cam wisely. I'll say it right here that I did NOT choose the cam without a LOT of input from folks who do this for a living and build some of the highest HP and most successful Pontiac powered engines on the planet! But that is how it is with these things, folks who NEVER do anything but Google will quickly jump on their keyboards and criticize your best efforts, kicking you in the nuts as much as possible for being so miss-informed and making bad choices, blah, blah, blah, instead of getting out there and spending $8000-10,000 on a similar engines and trying to get it done better.....FWIW
Anyhow, a couple of things that should be pointed out here. The cam is rated by Comp at .020" tappet lift not .006" from what I can remember. Also pulling it down on 108LSA would have spiked peak torque and VE would have occurred earlier with higher numbers, but it would not have made power further up in the rpm range. I've tested enough cams to know that doesn't happen. We do NOT go that route and know it is a death sentence for pump gas street engines with as much compression as we have in them. That fact is seldom pointed out by our critics, as they really haven't tried it and connected all the dots in building an effective high performance PUMP GAS Pontiac street engine. When I mean "effective" we're talking about plenty of vacuum at idle for power brakes, A/C, etc, strong off idle power, good throttle response, plenty of power in the "normal" driving range, strong mid-range and good upper rpm power, or basically a strong/broad/flat power curve. I'll add here that tight LSA works against you here, as it degrades idle quality, increases reversion (my term for stinky idle and "choppy" off idle to well past 1200rpms and sometimes not clearing up to 1800rpms or beyond). The tighter LSA also improves cylinder filling at lower rpms, and VE, so an engine with relatively high compression acts even higher, making it difficult, and sometimes impossible to effectively manage currently available pump fuel. I'd add here that the cam we tested is also a flat solid cam, and for years we have been told that you need to choose a solid cam about 10 degrees bigger than a flat hydraulic to make up the lost ground. That theory should be closer to 15-18 degrees now that I've got me feet wet a few times with those things. Solid camshafts also take the hydraulic action OUT of the equation, so aside from pushrod deflection the valves pretty sees the entire cam lobe. They also take lifter pump-up and other negative actions from the hydraulic lifters out of that deal, so in theory they should make more power if on par with a flat hydraulic camshaft pound for pound, and easily rev up past where we often see "lifter crash" or valve float issues with hydraulic camshafts. When I did that cam testing the idea was to replace the Crower 60919 (RAIV clone) with a flat solid cam to make about the same power with similar idle quality and street manners. Despite the XTQ lobes having quite a bit more lift, and 10 degrees more seat timing at .050", they didn't make nearly as much power as the RAIV cam. We did that test quite a few years ago, and it tells us several things about camshafts. First and foremost, folks ALWAYS look at .050" numbers when comparing camshafts. If the cams replacing the existing one has less actual seat timing, the valves are NOT going to be open as long despite the better lobes getting them up quickly. Cam companies for years has sold us on improved "area under the curve", telling us that we can reduce seat timing and still make up the lost cylinder filling abilities from the lost time in milliseconds the valves are off seat to move air thru the engine. I have come to find out that with flat camshafts this is not the case. Even when we stepped in with a larger HR cam for the last test session, with .361" lobes and 284/296, 230/242@ .050" seat timing the engine only responded with 3hp/4ft lbs torque improvement. It did offer slightly better idle quality with an improvement in vacuum at idle speed of 1.5". So it truly is a smaller cam compared to the RAIV cam it replaced, but even with the much larger lobes, greater .200" numbers, and .100" more lift it didn't make butt-loads more power than the Crower cam. Why didn't it? I say because the long seat timing Crower cam has the valves off seat quite a bit longer in milliseconds during each engine cycle. Even though the lift points are very low with the flat hydraulic lobes, the Pontiac engine with it's excellent low lift flow numbers sees this as an opportunity to move air. So basically seat timing trumped "area under the curve". Getting back to the topic at hand here. We continue to see relatively "small" cams come up short on power production with these engines, despite having "modern" or lobe profiles that get the valves up quicker and bigger .050" and .200" numbers. We also see folks quickly getting into trouble with these cams for managing lower octane fuel, as they really do improve cylinder filling at lower rpm's and raise dynamic compression when the engine events are not happening as quickly. What folks should really take away from this, even though it's old news, is how effective we can be with a relatively big cam in one of these engines by adding Rhoads lifters and high ratio rocker arms to it. We basically took a RAIV clone cam, topped with with Rhoads lifters, 1.73 ratio rocker arms, and mimicked the power of a $1000 custom ground roller cam with similar specs, for much less cost. The Rhoads lifters were not part of my engine for most of it's life, I only added them after that engine had been in service for several years. I did it as a test, and saw 2" vacuum improvement at idle, improved throttle response right off idle, and improved power below about 2500rpm's. I gained NOTHING at the track (converter stalls to 3500rpms) or anywhere else. So they really do work, despite some bad press they get from time to time. Since this testing we have also moved up to the V-Max version, which are much shorter travel and adjusted with a feeler gauge. For those reading this it means that you can set them precisely for the amount of bleed-off desired, which also controls engine noise. The older versions can get pretty loud on a really hot engine with thin oil and have given them a somewhat bad rap over the years. IF you plan on trying that deal, I highly recommend it, as old as the concept is you will end up with an engine with modern "variable valve timing", improved idle, better street manners, and you can use a bigger cam for greatly improved engine power, but it will be tamer in the normal driving range acting more like the 10 degree smaller cam you were looking at for that engine build. Sorry for the long rant, hope it helps some........Cliff
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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), |
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#88
01-22-2017, 10:01 AM
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You just build the most basic 455 that you see in here all the time. Just a simple 10:1 pump gas motor with decent aluminum heads and dual plane intake. Then throw in all these cams that everyone boasts about, the 041, 068, old faithful, and then mix it up with 4 or 5 custom grinds from Comp, Ultradyne, Bullet, Straub etc.... 5 off the shelf cams mixed up with 5 custom grinds. Maybe 2-3 rollers in there for good measure. It's been done before with an LS engine and the results were pretty interesting. |
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#89
01-22-2017, 10:10 AM
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Perhaps this is a key why builders like Kaase and BES are so great and can even build a better Pontiac. There are HUGE numbers of Ford and Chevy, with huge numbers comes greater competition. IF their engine theories did not translate into performance, they would fall to the back. The best are meticulous, methodical and exact. Don't subscribe to fudge factor guessing and are not afraid to test, test and test more. It does not matter where the information comes from (even Google). Or how we feel about the information. The information must be correct. |
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#90
01-22-2017, 10:15 AM
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I see the small gain you are stating with slightly more vacuum and smoother idle etc.... But I figured on my own that there would be no change at the track with the Rhoads, knowing they pump up instantly and a converter will flash above that point anyway. Because of that, I have always favored the 041 with standard lifters in the big 455. With only 230 @ .050 on a 113 lsa, and then installing that thing 4 degrees advanced, I've found that stick to idle fairly well in a 455 with good vacuum for brakes and only a slight lope, and easily manageable on the street. Not saying I wouldn't try the Rhoads, but sounds to me they might really come into their own on a slightly larger cam than the 041. |
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#91
01-22-2017, 10:22 AM
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#92
01-22-2017, 10:42 AM
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"This is a concept I find interesting. I didn't know you had the 041 with stock lifters for years. I thought you were always a Rhoads fan....etc....etc."
What folks don't compute into this equation is the static compression ratio. My engine had 92cc heads on it and zero decked with a flat top piston, so 10 to 1 compression. It idled good w/o bleed down lifters. I added them late in the deal as a test, and liked the results so stuck with them. These days I use Rhoads to make sure I get good lifters, not some off-shore junk, and that we get short travel lifters with the option to adjust the bleed-down rate if/as needed. IF I were to build the exactly same engine as powered my car for many years with lower compression, as is pretty much what the OP is doing here, the Rhoads lifters would NOT be optional using the 60919 camshaft. I built this exact same engine (6X-8 heads around 230cfm head flow, 9.3 to 1 compression) for a customer back around 2003 and 60,000 miles later he has it in a big car with mid 2.50 rear gears, TH400 with a low gear set and Continental 13" converter. It's an absolute ANIMAL for such a big car, with decent idle quality and good street manners. The Rhoads lifters, low gear set in the TH400 and excellent converter complete the "package" so it is a very well thought out Pontiac 455 powered project. Leave out one or more of the modifications and it wouldn't be nearly as successful. It's not ALL about the engine here, it's only part of the big plan, so folks need to look at making good power, then taking the needed steps to effectively use it.......Cliff
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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), |
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#93
01-22-2017, 10:54 AM
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Understood. I generally don't like to build really low compression engines myself unless there is some other circumstance out of my control.
I know what you mean about lifter quality, and that's also been an ongoing debate here. I bought my Johnson lifters from a board member here knowing the quality was better than off the shelf stuff from other cam manufactures, so I can understand wanting the Rhoads just from a quality standpoint alone. I'd like to build a 455 in the future with Rhoads, but use something a little bigger than the RAIV stick. Maybe something like 234-236 @ .050 intake duration and see how that does. |
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#94
01-22-2017, 11:16 AM
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"...I'd like to build a 455 in the future with Rhoads, but use something a little bigger than the RAIV stick. Maybe something like 234-236 @ .050 intake duration and see how that does.
https://www.summitracing.com/parts/crn-284281 http://www.pbm-erson.com/Catalog/Ers...t_E/ERSE310031 OR, if you side with the lower LSA guys, there is this Crower, with 108. http://www.cnc-motorsports.com/crowe...-camshaft.html Then, for a few bucks more, you can have EXACTLY the specs you want. Bullet shows several dozen lobes with 234-236 @ .050 specs. And you can get whatever LSA you want. http://www.bulletcams.com/Masters/Hlobes.htm http://www.bulletcams.com/Masters/ultradynemasters.html There are probably lots of cam grinders who will grind a custom to your specs. So, unless your budget forbids, you can have exactly what you want. Last edited by ponyakr; 01-22-2017 at 11:37 AM. |
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#95
01-22-2017, 11:29 AM
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Ken Crocie did a 455 pump gas engine build featured in Pontiac Enthusiast magazine that used a 'big' Comp Cams 320H hyd flat tappet cam with 268 degrees @.050 using Rhodes lifters. It used cleaned up Edelbrock heads with very little material removed. With a Performer RPM intake & Demon 850 carb it made 588 hp at 5800 rpm and 603 ft.lbs. torque at 4300 rpm. Very nice build.
To sort of mirror Cliff's comments. Here is an interesting comment Ken made from that article.... "If you examine the actual lift curve at the valves, a modern quick-lift hydraulic cam, in conjunction with high-ratio rockers and Rhodes Vari-Duration lifters, will approximate the valve-lift curve of a traditional solid roller up to about 0.600" lift. Over about 0.650" valve lift, the big-nose solid roller is king." That set up netted an actual 0.606-inch lift 'at the valve'. That article was almost 18 years ago. Fast forward... now today Ken also includes hydraulic roller cams in his builds. That and I'm not sure what he meant by a "traditional solid roller" in the comment. I'm sure in 18 years they have changed, especially with solid street roller cams now very popular. .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 01-22-2017 at 11:38 AM. |
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#96
01-22-2017, 11:44 AM
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A hyd flat around that size with 1.65 rocker can match an equiv .050 solid roller limited to only 1.5 rocker, when looking at dur at .200 valve, the flat falls behind somewhere just before .300 valve duration. Of course one could install higher ratio rockers on the solid, some engines will need it. Mid 170s @ .200 tappet is healthy for a street/ strip car. Last edited by pastry_chef; 01-22-2017 at 12:23 PM. |
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#97
01-22-2017, 11:51 AM
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Stated- "OR, if you side with the lower LSA guys, there is this Crower, with 108."
http://www.cnc-motorsports.com/crowe...-camshaft.html We have used that very same hyd flat tappet Crower cam in a nice 462 build for a local friend. Cleaned up 288-300 cfm Edelbrock heads (10.3:1 CR), Performer RPM intake w/ Holley vac. sec 750 carb. On a conservative dyno it made 513 hp at 5200/5300 rpm. A very nice STREET build with good idle quality. No issues at all ! .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 01-22-2017 at 11:57 AM. |
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#98
01-22-2017, 12:24 PM
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Cliff..My XTQ is doing exactly what I wanted it to do
With a good converter and drag radials it would be in 12`s with a 2.73 gear deburred 6X8 heads and headers on a track that isn't nearly 2700ft elevation and 100 temp.. That isn't to bad for a near stock street car that was going 110 miles round trip daily for work with a small cam of advertised duration 265/273 which is less than the 066 cam and less than the 254 2bbl cam.. and yes I know the seat to seat is different lifts... point being my XTQ isn't a big seat to seat cam Last edited by Formulas; 01-22-2017 at 12:49 PM. |
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#99
01-22-2017, 12:24 PM
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#100
01-22-2017, 12:57 PM
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A cam shootout would be fun but remember flow doesn't start or stop at .050
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