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#61
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Dave thanks for posting . Even though my RAIV motor liked the reverse split cam my E head 500" with a 268/272 solid roller liked tighter lash on the exhaust telling me it would have liked more on the exhaust. My 470/409 did not like more ratio on either side or tighter loose lash.
I think unless you put multiple cams in the same motor, try different ratios on the same motor, tighten loosen lash on the same motor you really don't know what it really likes. Why the stockers have shelves full of cams(can convertors )
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#62
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Good thread and a lot of good information. However, I feel you need to match the cam with the parts you are using and you will generally need a tighter lobe separation than 114 if you're looking for cutting edge performance. However, I cannot stress how important it is to match all the components! The new norm is 10 second naturally aspirated pump gas street cars.
In 2006 I was running my 80 T/A with a 9.1 compression 455, ported cast iron heads, 3.42 gears, tight 11" Coan 2800 rpm converter and a Comp hydraulic roller 242/248 with an 110 LSA. Weighing over 3900 lbs. the best ET was 11.35 @ 119.3 mph. For the last 2 years I've been running the same 3.42 gears, the car has lost 100 pounds and uses 318 cfm E-heads, Torker II and a tight 10" converter with a solid roller 259 @.050 on a 108 LSA, I've only had it to the track 3 times but have run consistent 10.7 @125 mph. A friend was running a 9.1 455 with E-heads, 10" inch converter and 3.55 gears in a '64 GTO weighing 3670 lbs. and has run 11.2 @ 119 mph using the dreaded Comp XR288HR which has a 110 LSA. My brother ran a 9.1 compression 455 with 310cfm E-heads, a solid roller with 254 duration @ .050 ground on a 108 LSA, and went 10.8 @ 124 mph the first time out, using a tight 10" converter, 3.70 gears and weighing 3720 lbs. |
#63
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#64
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"...The new norm is 10 second naturally aspirated pump gas street cars..."
Wow, it's the "norm" to have 10 sec street cars ! It may be the "norm" where you live. But in my area, there are lots of dedicated (race only) bracket cars still running 11's. I can hardly imagine driving around on hard street tires, in a 10 sec car. Is this some sort of a status symbol for guys with the $$ to do it ? I'm not badmouthing anybody. Hey, if I had more money, I'd spend most of it on racing Pontiacs. But I still would not try to drive a 10 sec car on the street. There are 12 sec cars that will make all the tire smoke you want. And street racing is illegal, ain't it ? Last edited by ponyakr; 06-04-2015 at 12:48 PM. |
#65
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My car absolutely screams once it gets some RPM, but it is a little doggy just off-idle. I have a stick and you can kind of feel it want to pull the engine down when you pull out in traffic. Swapping from an open to a four hole spacer on the T2 helped but not as much as I'd like. |
#66
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I've been involved with several NHRA Stock Eliminator racers and they all use tighter lobe seps to produce some impressive power with unported heads, but a HUGE factor why these cars perform as they do is that everything is optimized in the entire drivetrain which requires $$$$. One customer with a legal 77 bird has gone 11.27 @ 117mph with a completely legal 350 Pontiac and only .363" valve lift, but I think he has more in the trans than the entire engine!! so you can't really compare what these cars do to your average street/strip car. |
#67
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I do agree with you 100% that whatever route you decide to take matching all the drivetrain components is critical to achieving optimum performance. This typically takes time at the track to sort out all the details, ta man is a good example of that. You can't just keep throwing parts at something if you never optimize what you already have and make incremental changes which in some cases might make things go backwards before you can go forward, but if you make too many changes all at once you will never really know which ones are helping or hurting. |
#68
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I think Paul was just saying with today's better flowing heads it is not that hard to get a 455 Pontiac in the 10s and even be a fairly mild streetable car. My pump gas motor in the 78 TA can do it with good air(the hard part in Houston) and my light wheels no spare 3750 lbs. It is easily reproducible and even has a HFT cam that pulls plenty of vacuum for power brakes. 320 cfm round port E heads, Torker II I did spend a lot of time blending and had to raise the roof, out of the box Holley 850 DP-one jetting leaner, 2" Hooker Super comps into a 3" X and mufflers and full tailpipes. 9" slicks and a 10" Continental Convertor. No Caltracs, slapper bars just some front half biased springs.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#69
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As far a spending money I agree with you , but there have been a lot of sets of $500 billet valve covers sold! Although I've never bought any. The status symbol we are seeing around here is 1000 horsepower to the rear wheels! |
#70
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"...The status symbol we are seeing around here is 1000 horsepower to the rear wheels!"
Yeah, I can see where that would come in handy if a ricer pulled up beside you, and revved up his engine. |
#71
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"I disagree with your statement that today's cutting edge performance is made with tighter lobe seps, the guys making big NA power are using wide lobe sep cams and turning big rpm to make the power they do and this isn't specific to Pontiacs."
I agree, the trend is to spread the lobe centers on high RPM big power engines and extend the exhaust duration. I was thinking of this when I was typing my original post, but that is mostly for high rpm race engines. I have not seen many Pontiacs running in the ten's with 114 LSA's, if there are some examples out there I would like to hear about your combinations. Please list them. |
#72
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We spent a bunch of time and money doing R&D on 535-541 pump gas combo's using Marcel's 541 shortblock as a test mule. In the end his engine with a set of our wide ports and a 276/286 @ .050" 114 lobe sep cam, ported 4500 Victor intake etc. produced 826hp on pump gas with 10.8 to 1 compression. He put the engine in his 81 Lemans street car and ran as quick as 9.68 @ 140ish mph with a race weight of 3920lbs (car still has PW, full interior etc.). The car was very difficult to get down the track with more aborted runs than good ones as he typically ran it at street legal events on 10" slicks, but when the track was good it did run a bunch of 9.70's-80's. Not a great true street combo so we are working on a new combo with a big hyd. roller that should still put the car into the 9's with good conditions but be a lot more street friendly. Before the 541 Marcel ran a 10.6 to 1 468 with a set of 310cfm hand ported E-heads, 271/279 @ .050 .675"lift 112 lobe sep solid roller in his 81 Lemans which had a race weight at that time of around 3800lbs, the car ran consisitent mid 10's with a best of 10.43 @ 127+mph and he drove the car on the street a lot at that point. A few years ago a customer with a stock weight, stock wheel well 66 GTO wanted to have a super low maintenance engine to run in the mid 10's. He wasn't concerned with pump gas and actually preferred to run race gas as he was worried about the quality of fuel at the pump so we built a 505 with flat top pistons and a set of our 340-350cfm E-heads and ported 4150 Northwind intake. For a cam we used a 252/262 hyd. roller .608"/.638" gross valve lift 114 lobe sep with 857 hyd. roller lifters (old style), Compression is a hair over 12 to 1. Intake is topped off with a Pro Systems 1000cfm HP 4150 carb. The engine effortlessly made 752hp on the dyno and shifted @ 5800rpm lays down 10.0's 10 teens and if he shifts it at around 6400-6500rpm runs into the 9's. This is right off the trailer and there hasn't been any need to do any tweaking since the car is only legal for 10 flat. He runs a TH400 4000 stall ATI conv. and 3.73 gears with a 28" tall slick, race weight is around 3500lbs. This same combo at 461-474ci using a stock block and 10.75 to 1 would easily run mid to low 10's also. These are just a few I can think of off the top of my head. I wasn't disputing that you can run quick with the tighter lobe seps, but a street/strip car with wider lobe sep cams (read less overlap) will run cleaner and have a broader less peaky rpm range. |
#73
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As far as the last combo mentioned you think a 462ish engine with 10.75 compression would run low ten's with a 252/262 cam? Last edited by PAUL K; 06-04-2015 at 04:08 PM. |
#74
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I do believe that a 3500ish lb car all dialed in could run bottom of the 10's with the last combo. Will that happen first time out? I doubt it. Good discussion, if a guy could just do R&D all day everyday!!! Unfortunately that doesn't pay the bills. |
#75
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Oh and its great seeing Dave Bisschop posting.....Dave ,Marcel and my wife are the reason why my car runs like it does!A set of surprise heads under the Christmas tree does wonders for performance! Last edited by ta man; 06-04-2015 at 05:43 PM. |
#76
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We ran the 110 LSA for two seasons and tried changing the cam timing several times. It liked tight lash, 1.6 rockers over the 1.5s it ran best about 5 degrees advanced and was running 10.5 @ 127. We swapped the cam and installed it 5 degrees advanced and started with the tight lash. Off the trailer we went mid 10.3 @129. We played with that for a couple of seasons. It didn't make much of a difference moving the cam timing around but it still liked the lash tight so we switched to a UD 275/283 on a 108 and picked up again. Now the engine liked 103 ICL and the lash at .026. We played around with that for a while and ran 10.1 @ 131 mph. The engine was put to the side and after a few years I just freshened it and installed a Comp 280/284 .440 LL cam ground on a 105. I hope to get a chance to test it in my brothers 70 Firebird this year but we are into June already and still behind. I also degreed the old 275 UD so we can swap them easily in the car if we feel we want backwards. |
#77
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"I'm not suggesting everyone run out and slide 114 lobe sep cams in their engine. The reality is lobe sep isn't really what we should be looking at as overlap,"
+2 I saw several posts where folks posted nice number with tighter LSA, but NONE of them were 260 duration advertised cams and 220's @ .050"....NOT going to happen. Those little cams are, and always have been PISS-POOR choices for these engines, at any compression ratio. What simply happens here is that you take a HUGE undersquare engine, that's already trying to make ALL the power right off idle, then put a cam in it that tries to make it better at what it already does best. Top that off with the excellent cylinder filling abilities of these "short seat timing" cams, and you have just built yourself a Pontiac 455 "turd". I've had quite a few of these vehicles brought up here to tune, and ALL of them had the same symptoms, "quirky" idle, "stinky" shi@ coming out the pipes, octane sensitive, and did NOT like "normal" timing and fuel curves. Not to mention they didn't make any kind of impressive power, and were DONE before 5000rpms, even with really good flowing heads on them. I don't know who's been keeping score here? But going from 428hp @ 4900rpms to 514hp at 5900rpms, and 516ft lbs tq to 559ft lbs, better idle, less stinky shi@ out the exhaust, etc is a nice improvement from only changing ONE PART.....IMHO......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), |
#78
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"I don't know who's been keeping score here? But going from 428hp @ 4900rpms to 514hp at 5900rpms, and 516ft lbs tq to 559ft lbs, better idle, less stinky shi@ out the exhaust, etc is a nice improvement from only changing ONE PART.....IMHO......Cliff"
I'll toast to that. Good to hear Dave post as well- I really enjoyed working with him on my build. Thanks everyone for posting their experiences and knowledge- great thread. |
#79
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+2, love to see Dave take the time to post on here as well. It's always great to see lots of good tech stuff posted, even if it's "googled" up, but even better when it comes from one of the guys who's really making it happen with these things. I like Dave's approach to making power, you can research this stuff to death, but at some point you've got to get your hands dirty and try stuff out to see what works and what doesn't.
We talk on occasion thru emails, but both of us do this for a living so have to spend most of our time in the shop to keep the bills paid and mama happy! I'm blessed with having really good help so it frees me up to spend a little time each day on the Forum. Dave has a full plate with stuff falling off all sides of it, and I think he may be a "one man show" at this point, or close to 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), |
#80
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I know it is difficult to boil it down to generalities because each combo is specific, but is there a range for street overlap vs. street/strip vs. strip only that novices can use? For instance I told you I wanted to make in the area of 450hp with my daily driver 433(4"stroke .030" over 400 block) with iron heads and intake, also using RARE manifolds instead of headers and you said the Stump Puller was the cam. In my calculator it has 63.5° of overlap. Would 75° of overlap be way too much? Is ther a sweet spot for manifolds vs. headers? What does it take to figure out how much overlap? Thanks much for spreading the wisdom!
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Karl |
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