Input needed on daily driver sbc truck build

[houser45]

I like the eq vortec idea but, i already have a street dominator 2 300-36 and i would really like the 10.0 -10.5 to 1 compression of the aluminum

[Monza355]

I’m doing a similar build with parts i have laying around. I’m going to use an older set of Dart II 200cc iron heads.
If i were going to buy a new set I would probably go with 195cc Profiler’s like you were thinking about even though the 180’s might be a better choice for an application like this..

Since this is a daily driven application what fuel octane are you aiming for and what carburetor and ignition ?

[David Vizard]

I dont do a lot of street engines usually circle track engines so i am asking for advice on my shop truck build. Chevy 85’ square body 4x4. Nv 4500 3.73 gears 33” or 35” tires. 400 sbc. Cast crankshaft, prepped stock 5.7 rods, speed pro hyperutectic dished or flat top pistons. Depending on what chamber size. Compression ratio will be 10 to 1. Comp 268xe on 1.5/1.5 rockers. Budget Aluminum Assault sbc 200cc heads. 2.02/1.60. Possible Promaxx or Profiler 195’s? Just not wanting to break the bank on this one. Too much camshaft? Assault heads?

That cam will be 4 degree too wide if you are going to run 2.02/1.6 valve combo on a 400 inch build. It will cost at least 30 LBS FT and a like amount of HP
DV

[gottago]

If the cam were to be narrowed 4 degrees, would it still be eligible for the daily driver class? Would you stick with the same I/o duration? Would it run the same octane fuel?

[houser45]

I dont do a lot of street engines usually circle track engines so i am asking for advice on my shop truck build. Chevy 85’ square body 4x4. Nv 4500 3.73 gears 33” or 35” tires. 400 sbc. Cast crankshaft, prepped stock 5.7 rods, speed pro hyperutectic dished or flat top pistons. Depending on what chamber size. Compression ratio will be 10 to 1. Comp 268xe on 1.5/1.5 rockers. Budget Aluminum Assault sbc 200cc heads. 2.02/1.60. Possible Promaxx or Profiler 195’s? Just not wanting to break the bank on this one. Too much camshaft? Assault heads?

That cam will be 4 degree too wide if you are going to run 2.02/1.6 valve combo on a 400 inch build. It will cost at least 30 LBS FT and a like amount of HP
DV

So would a better choice to drop down to the 262xe and have lsa narrowed to 107/108?

[David Vizard]

If the cam were to be narrowed 4 degrees, would it still be eligible for the daily driver class? Would you stick with the same I/o duration? Would it run the same octane fuel?

The cam LCA is not a factor that dictates the street-ability of the cam. If you have been told that a wide LCA is needed for the street and a narrower one for competition then you have been told wrong. The key factor is the overlap involved. For any given head, displacement and C R there is only one optimal LCA. It does not vary.

If I were to run your engine spec through my highly accurate TorqueMaster cam selection program it would show a required LCA of 104 - 105. As such that 268 profile on both the intake and exhaust would make a dynamite selection for your 400.

Many years back I built a magazine feature motor to show off a Comp valve train in a 10.5/1 350. The cam Comp sent was a 268 extreme on a 110 lca.

I told them a 108 would work better with the 2.02/1.6 valve sizes equipping the ported 186 production head castings but they wanted to use what they sell. At this I bought a 268 extreme on a 108 lca. This cam made 449 lbs-ft and 442 hp which was up 22 lbs-ft and 20 hp on the 110. When I told them the results they went with my 108 cam for the story and refunded what it cost me.

DV

[gottago]

The cam LCA is not a factor that dictates the street-ability of the cam. If you have been told that a wide LCA is needed for the street and a narrower one for competition then you have been told wrong. The key factor is the overlap involved. For any given head, displacement and C R there is only one optimal LCA. It does not vary.

I believe that is true but...

If I were to run your engine spec through my highly accurate TorqueMaster cam selection program it would show a required LCA of 104 - 105. As such that 268 profile on both the intake and exhaust would make a dynamite selection for your 400

What happens to driveability in regard the subject criteria ( daily driver ) Idle characteristics, fuel mileage, type of fuel required, torque converter specs etc..

If you try to maintain same idle characteristics as the xe 268 but on a 104-106 lsa you have to shorten durations but will that not shorten the powerband also? Soon you are driving a tractor..

[David Vizard]

The cam LCA is not a factor that dictates the street-ability of the cam. If you have been told that a wide LCA is needed for the street and a narrower one for competition then you have been told wrong. The key factor is the overlap involved. For any given head, displacement and C R there is only one optimal LCA. It does not vary.

I believe that is true but...

If I were to run your engine spec through my highly accurate TorqueMaster cam selection program it would show a required LCA of 104 - 105. As such that 268 profile on both the intake and exhaust would make a dynamite selection for your 400

What happens to driveability in regard the subject criteria ( daily driver ) Idle characteristics, fuel mileage, type of fuel required, torque converter specs etc..

If you try to maintain same idle characteristics as the xe 268 but on a 104-106 lsa you have to shorten durations but will that not shorten the powerband also? Soon you are driving a tractor..

If you have to consider a wider LCA to get the idle vacuum sought then all you have done is chosen a cam with too much duration. Spreading the LCA my improve the idle but it costs torque and hp everywhere in the rpm range.

Selecting the optimal LCA first and then the overlap to give the desired idle qualities locks in the duration. Result - the BEST cam for the job.

Bottom line is you need to be in a position to come up with the right LCA in the first place.

Anyone that responds saying the LCA is a result not an input will, I gaurentee, have far less cam testing/specing experience than me so watch out for that bit of dud advice.

DV

[gottago]

If you have to consider a wider LCA to get the idle vacuum sought then all you have done is chosen a cam with too much duration. Spreading the LCA my improve the idle but it costs torque and hp everywhere in the rpm range.

Selecting the optimal LCA first and then the overlap to give the desired idle qualities locks in the duration. Result - the BEST cam for the job.

thanks DV.. I like hearing that said although I've not been that successful in achieving the intended results. When I've locked in a duration that gave a nice smooth idle on a tighter lca I seem to shorten my rpm range. If I pick a duration that restores the upper rpm band, the idle goes away on me. Solution for me was to compromise and spread it out a bit on the lca. (daily driver builds) Perhaps the definition of daily driver is a bit different for everyone too.

Having said that, If I could get a tighter lca to do the same as what I am doing by going wider lca and a bit more compression for a smoother idle and higher rpm band, I would.

[rfoll]

If you have to consider a wider LCA to get the idle vacuum sought then all you have done is chosen a cam with too much duration. Spreading the LCA my improve the idle but it costs torque and hp everywhere in the rpm range.

Selecting the optimal LCA first and then the overlap to give the desired idle qualities locks in the duration. Result - the BEST cam for the job.

thanks DV.. I like hearing that said although I've not been that successful in achieving the intended results. When I've locked in a duration that gave a nice smooth idle on a tighter lca I seem to shorten my rpm range. If I pick a duration that restores the upper rpm band, the idle goes away on me. Solution for me was to compromise and spread it out a bit on the lca. (daily driver builds) Perhaps the definition of daily driver is a bit different for everyone too.

Having said that, If I could get a tighter lca to do the same as what I am doing by going wider lca and a bit more compression for a smoother idle and higher rpm band, I would.

My question is, how much rpm do you really need for a daily driver? I have never found a need for much more than 5500 rpm on my street cars. That's good for 100 mph in second gear in my Impala. The performance under 3000 rpm is really important, that is where the engine lives.

[David Vizard]

If you have to consider a wider LCA to get the idle vacuum sought then all you have done is chosen a cam with too much duration. Spreading the LCA my improve the idle but it costs torque and hp everywhere in the rpm range.

Selecting the optimal LCA first and then the overlap to give the desired idle qualities locks in the duration. Result - the BEST cam for the job.

thanks DV.. I like hearing that said although I've not been that successful in achieving the intended results. When I've locked in a duration that gave a nice smooth idle on a tighter lca I seem to shorten my rpm range. If I pick a duration that restores the upper rpm band, the idle goes away on me. Solution for me was to compromise and spread it out a bit on the lca. (daily driver builds) Perhaps the definition of daily driver is a bit different for everyone too.

Having said that, If I could get a tighter lca to do the same as what I am doing by going wider lca and a bit more compression for a smoother idle and higher rpm band, I would.

gottogo,

It seems I have over the last 25 years I've explained how all this works a million times. Sure I know it's not a million but it sure seems so. It is getting painful to have to go through just one more lengthy explanation so to make things easier for me why don't you send me the specs of your motor and I will run it through TorqueMaster at no charge.

PM me the engine spec - here is what I need.

Bore
Stroke
CR
In. valve Dia.
Ex. valve Dia.
What kind of seat job?
Rod length
R/R intake
R/R ex.
Peak Power rpm
Idle vacuum required

We will start with that and if I need anything else we will cover it via PM's
DV

[gottago]

D.V. thank you, will do! I apologize for the simplistic questions and sortof knew I was going way back into some pretty basic theory you have spoken on for years. But I did notice on many an auto talk site how common it is for this topic to come up in various ways. The term lsa or lca gets bandied about by everyone from the fuel mileage crowd to racers to vvt and dohc specs etc all claiming some characteristic and benefits of a wider or narrower lca. I've driven quite a few all the way from 104 to 117 lca. The lsa can change the way an engine responds quite dramatically. Knowing which lsa to use for the intended purpose in combination with everything else is a bit tricky. Even some of our terminology has differing interpretations, like the daily driver or the street/strip combo. One guys daily driver is another mans weekend racer etc..

My question is, how much rpm do you really need for a daily driver? I have never found a need for much more than 5500 rpm on my street cars. That's good for 100 mph in second gear in my Impala. The performance under 3000 rpm is really important, that is where the engine lives.

I'm good with the 5500 rpm range in most real daily drivers, big blocks for sure, smalls sometimes like to run them up a bit higher. All dependent on vehicle weight, gearing, usage etc..

[David Vizard]

D.V. thank you, will do! I apologize for the simplistic questions and sortof knew I was going way back into some pretty basic theory you have spoken on for years. But I did notice on many an auto talk site how common it is for this topic to come up in various ways. The term lsa or lca gets bandied about by everyone from the fuel mileage crowd to racers to vvt and dohc specs etc all claiming some characteristic and benefits of a wider or narrower lca. I've driven quite a few all the way from 104 to 117 lca. The lsa can change the way an engine responds quite dramatically. Knowing which lsa to use for the intended purpose in combination with everything else is a bit tricky. Even some of our terminology has differing interpretations, like the daily driver or the street/strip combo. One guys daily driver is another mans weekend racer etc..

My question is, how much rpm do you really need for a daily driver? I have never found a need for much more than 5500 rpm on my street cars. That's good for 100 mph in second gear in my Impala. The performance under 3000 rpm is really important, that is where the engine lives.

I'm good with the 5500 rpm range in most real daily drivers, big blocks for sure, smalls sometimes like to run them up a bit higher. All dependent on vehicle weight, gearing, usage etc..

You have not answered my questions.

DV

[gottago]

On the way...

[gottago]

Ok done, sent my specs via P.M. Apologies to the OP, didn't mean to sidetrack..