[Dave Bisschop]

Originally Posted by PAUL K

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.

For many years most of the street/strip stuff we built was 108-110 lobe seps and we made good power, but when we started going to wider lobe seps over 15 years ago we found we could get much better driveability, way less "stink" out the tail pipes and extend the rpm range, this was with flat tappet solid lifter cams. For most of the solid roller race stuff we still used 106-108 as we only had cast cranks to work with but once the forgings became available we started going to wider lobe seps and in a lot of cases less duration and ended up with more power and quicker ET's at the track with more rpm capability. I feel a lot of the gains we've seen with the wider lobe seps also has to do with the increased efficiency with the cylinder heads. No doubt you can make some great power with the tighter lobe sep cams (we ran a 104 LSA in our 65 GTO), but I found at some point you will hit a wall. 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 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.

[PAUL K]

"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.

[Dave Bisschop]

Originally Posted by PAUL K

"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.

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, valve opening and closing events is really what should be looked at and the lobe sep ends up being what it is, but of course when spec'ing a cam and choosing the lobes to run part of placing the cam order is to specify what LSA the cam should be ground on, trying to remember all those events off the top of your head for bench racing discussion would get a little confusing. About 95% of my customer base is street/strip guys, about 6-7 years ago when the economy was booming we had a lot more customers building higher end larger engines, but most still wanted pump gas as they wanted to drive their cars on the street.

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.

[PAUL K]

Originally Posted by Dave Bisschop

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, valve opening and closing events is really what should be looked at and the lobe sep ends up being what it is, but of course when spec'ing a cam and choosing the lobes to run part of placing the cam order is to specify what LSA the cam should be ground on, trying to remember all those events off the top of your head for bench racing discussion would get a little confusing. About 95% of my customer base is street/strip guys, about 6-7 years ago when the economy was booming we had a lot more customers building higher end larger engines, but most still wanted pump gas as they wanted to drive their cars on the street.

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.

Thanks for posting, good info. I'm not surprised at all the big inch engine responded well to the wider LSA, also not surprised the higher compression engine liked it. Years ago we were running a 455 with an UltraDyne 271/279 .426 LL cam on a 110. When we switched to 108 LSA the car picked up a solid tenth and a half and almost 2 mph.

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?

[Dave Bisschop]

Originally Posted by PAUL K

Thanks for posting, good info. I'm not surprised at all the big inch engine responded well to the wider LSA, also not surprised the higher compression engine liked it. Years ago we were running a 455 with an UltraDyne 271/279 .426 LL cam on a 110. When we switched to 108 LSA the car picked up a solid tenth and a half and almost 2 mph.

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?

There are so many variables that will affect performance, your cam swap obviously showed that the 108 LSA was better suited to the rest of the combo. Does that mean if you had made other changes in the combo that the 110 LSA could have been quicker than the 108? When you did the cam swap did you keep the ICL in the same position? It all goes back to what you said earlier that matching the components is critical. With all the info out there it's fairly easy to get into the ball park, but there are a ton of "grey" areas that require tweaking to get things optimized.

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.

[PAUL K]

Originally Posted by Dave Bisschop

There are so many variables that will affect performance, your cam swap obviously showed that the 108 LSA was better suited to the rest of the combo. Does that mean if you had made other changes in the combo that the 110 LSA could have been quicker than the 108? When you did the cam swap did you keep the ICL in the same position? It all goes back to what you said earlier that matching the components is critical. With all the info out there it's fairly easy to get into the ball park, but there are a ton of "grey" areas that require tweaking to get things optimized.

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.

Yes, you are right about someone else paying the bills, while R&D is done!

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.

[72LuxuryLeMansLa.]

Originally Posted by Dave Bisschop

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, valve opening and closing events is really what should be looked at and the lobe sep ends up being what it is, but of course when spec'ing a cam and choosing the lobes to run part of placing the cam order is to specify what LSA the cam should be ground on, trying to remember all those events off the top of your head for bench racing discussion would get a little confusing. About 95% of my customer base is street/strip guys, about 6-7 years ago when the economy was booming we had a lot more customers building higher end larger engines, but most still wanted pump gas as they wanted to drive their cars on the street.

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.

Dave,

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!

[Dave Bisschop]

Originally Posted by 72LuxuryLeMansLa.

Dave,

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!

Good question and while I'd love to tell you I have some magical formula that I use the reality is all my knowledge in this area has been from trial and error testing on the dyno. That being said using the Wallace calculator (Thanks Steve for posting the link) the old SP cam shows 64 deg, new one shows 61, OF on a 112 is 73 and the OF on a 114 is 69. I haven't done a manifold vs. header test with the new version of the SP, but I think it's safe to say it will work well with the RA manifolds since the old version the most we ever saw on the dyno back to back was 8hp less with the RARE GTO 2.45 manifolds vs. a Hooker SC 1 3/4" header. We had a 491 on the dyno a number of years ago with a set of our 300-305 KRE D ports, Performer RPM etc. with the OF on a 114, the engine made 567hp with the manifolds and 582hp with the headers, previously we'd seen a good 30hp spread comparing headers to manifolds in another engine we tested with the OF on a 112. So looking at the data I'd say when you start to go beyond 70 deg. overlap using the Wallace calculator the hp difference is going to get into the 20+ range quickly as the overlap increases. Under 65 deg. and the difference is more like under 10hp. Years ago we did a manifold vs. header test on a iron headed 9.5 to 1 467 with an Ultradyne flat tappet cam 263/271 @ .050 on a 112, the manifolds killed 45 hp at peak and 75hp at 6000rpm, using the .020" rated duration numbers the overlap calculates to 76 deg. I think this gives a general idea what to look for when deciding if a cam is a good choice to run with the RARE manifolds.

[72LuxuryLeMansLa.]

Originally Posted by Dave Bisschop

Good question and while I'd love to tell you I have some magical formula that I use the reality is all my knowledge in this area has been from trial and error testing on the dyno. That being said using the Wallace calculator (Thanks Steve for posting the link) the old SP cam shows 64 deg, new one shows 61, OF on a 112 is 73 and the OF on a 114 is 69. I haven't done a manifold vs. header test with the new version of the SP, but I think it's safe to say it will work well with the RA manifolds since the old version the most we ever saw on the dyno back to back was 8hp less with the RARE GTO 2.45 manifolds vs. a Hooker SC 1 3/4" header. We had a 491 on the dyno a number of years ago with a set of our 300-305 KRE D ports, Performer RPM etc. with the OF on a 114, the engine made 567hp with the manifolds and 582hp with the headers, previously we'd seen a good 30hp spread comparing headers to manifolds in another engine we tested with the OF on a 112. So looking at the data I'd say when you start to go beyond 70 deg. overlap using the Wallace calculator the hp difference is going to get into the 20+ range quickly as the overlap increases. Under 65 deg. and the difference is more like under 10hp. Years ago we did a manifold vs. header test on a iron headed 9.5 to 1 467 with an Ultradyne flat tappet cam 263/271 @ .050 on a 112, the manifolds killed 45 hp at peak and 75hp at 6000rpm, using the .020" rated duration numbers the overlap calculates to 76 deg. I think this gives a general idea what to look for when deciding if a cam is a good choice to run with the RARE manifolds.

Got it. Thanks Dave, great info for the board!

[Steve C.]

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