CID/RPM/CFM/HP

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F-BIRD'88
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Re: CID/RPM/CFM/HP

Post by F-BIRD'88 » Sun Nov 05, 2017 1:53 pm

Do you still have that Comp cams XFi hyd roller camshaft?

I can show you how to make both of those cams WORK a LOT better for you.

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Re: CID/RPM/CFM/HP

Post by skinny z » Sun Nov 05, 2017 2:29 pm

randy331 wrote:
Sun Nov 05, 2017 1:32 pm


It's just part of the compromises one has to decide on.
But, I think people believe they need more than they do.

I got one 383 with a 224*-244* on 110* LSA cam with 2.02" / 1.55" valves and 50* seats. It has very little flow around TDC and it is a very surprising running engine. Made a surprisingly good power curve on the dyno and drives around in a heavy car very nice.

Too much overlap is probably worse than not enough.

Randy
I'd like to follow up on this.
Last edited by skinny z on Sun Nov 05, 2017 2:30 pm, edited 1 time in total.

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Re: CID/RPM/CFM/HP

Post by skinny z » Sun Nov 05, 2017 2:30 pm

F-BIRD'88 wrote:
Sun Nov 05, 2017 1:53 pm
Do you still have that Comp cams XFi hyd roller camshaft?

I can show you how to make both of those cams WORK a LOT better for you.
I'd like to follow up on this too.
It'll have to be later for both though.

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Re: CID/RPM/CFM/HP

Post by F-BIRD'88 » Sun Nov 05, 2017 2:49 pm

Think about finding yourself 8 SBC solid roller lifters (new) . Ya you read that right 8.. 1/2 a set.
And 8 or 16 of the valve springs that are used on the typical street SOLID Roller SBC
valvetrain (1.46" diameter Dual coil) with the matching retainers.
EG: Comp 977 Crane 96870 or K motion K800.

You will need 8 for sure (1/2 set) or all 16 for this.

Keep your eye out for 8 (1/2 a set) high ratio rocker arms 1.65 to 1.7 ratio SBC ( not Ford)
8 they are for the intake side only.

Intakes will be solid roller....exhaust will be hyd roller.
Intake benefits from the high rpm stability of the solid roller lifters
with the increased rocker ratio and valve speed action
controled better with the better valve springs.
Exhaust benefits from the auto lash 0 fuss of the 8 hyd roller exhaust lifters.

The control of the intake valves is more important than the ex side
especially if when you jack up the rocker ratio on a intense fast design cam lobe like the XFi hyd roller lobes.

The valve train rev limit will be a LOT higher. The top end engine power will be better. The valve train noise at idle will be BETTER than before.
You'd set the intake valve lash COLD very tight at say .001" to .003" COLD
on the 8 intake rockers.

Set the exhaust once, as usual for a hyd cammed motor at 0 lash with a bit of preload.

Now you got a very stable intake valve that lifts higher and FASTER too where it counts.
Requires very occasional,,, simple quick valve lash maintenance of the 8 intake valves ONLY.
Small bet changes in the intake valve lash settings tunes intake valve true running seat duration events.

The exhaust side is as usual no fuss hyd roller.

MORE RPM LESS noise more adjustability More valvetrain stabiity.
More torque and POWER. Long service life.

if you are handy taking apart hyd roller lifters you could convert your 8 hyd roller lifters to solid roller like lifters by shimming up the hyd plunger solid at the correct running plunger height. Eliminating the hyd function.
Then adjust the 8 intakes like a solid lifter but tight lashed (.001" to .004" ish Cold) The intake lash will increase a small bit when the motor is HOT.

it won't change that much. It is the exhaust side that sees a bigger change in cold hot lash. Thus the NO fuss ex Hyd roller lifters.

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Re: CID/RPM/CFM/HP

Post by F-BIRD'88 » Sun Nov 05, 2017 3:10 pm

Now you are all set for big power and 7000 rpm performance when you supercharge that 355... with those heads and all and go reliably in the 11's in that Crappy Edmonton air. It will even go GREAT in the snow. "uncorrected" too.

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Re: CID/RPM/CFM/HP

Post by novadude » Sun Nov 05, 2017 5:23 pm

randy331 wrote:
Sun Nov 05, 2017 1:32 pm
skinny z wrote:
Sun Nov 05, 2017 12:02 pm
randy331 wrote:
Sun Nov 05, 2017 10:15 am

IVC seems to run the show for the most part.

Randy
And overlap? Where do you slot that in?
It's just part of the compromises one has to decide on.
But, I think people believe they need more than they do.

I got one 383 with a 224*-244* on 110* LSA cam with 2.02" / 1.55" valves and 50* seats. It has very little flow around TDC and it is a very surprising running engine. Made a surprisingly good power curve on the dyno and drives around in a heavy car very nice.

Too much overlap is probably worse than not enough.

Randy
That's an interesting engine. Would love more details. Am I reading correctly - 20 deg more exhaust duration @ 0.050"? A bit unconventional.

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Re: CID/RPM/CFM/HP

Post by skinny z » Sun Nov 05, 2017 8:48 pm

F-BIRD'88 wrote:
Sun Nov 05, 2017 2:49 pm
Think about ...
With all due respect, we're really getting off topic.
That said, I don't have the need (nor do I want) such "exotica" (for lack of a better word). The valvetrain I have assembled is more than up to the task it was designed for. As a matter of fact, from the findings here, anything I assemble reusing the heads in question and the additional displacement is more than likely to make peak at a lower RPM than the current 355. Sounds like 6000 RPM or so. The valvetrain is even more secure at that point.
The supercharged 355 is intriguing and a blower is my forced induction of choice however it's most definitely not in the cards.
Thanks just the same.

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Re: CID/RPM/CFM/HP

Post by skinny z » Sun Nov 05, 2017 8:54 pm

randy331 wrote:
Sun Nov 05, 2017 10:15 am
skinny z wrote:
Sun Nov 05, 2017 10:06 am


So, is that to say that a 110 LSA will not be significantly different in power and torque than one with 106 LSA provided the overlap remains the same?
In my experience no. At least not if both cams are of the same lobe family ( lobe speed and lift ) and installed on the same ICL. I think a lot of these types of changes just get cams put in as the cam card shows, so the 106 ends up advance and the engine likes the earlier IVC point and people see that and think it's the LSA that made the difference.

IVC seems to run the show for the most part.

Randy
An excerpt from a well respected engine builder.

A 108 Lobe Centerline Angle (also called a Lobe Separation Angle) for this particular engine (a 355 SBC with 186 heads and a 10/1 CR gave the widest and best output on a 108 LCA. Spread that angle and watch the torque and HP drop.

Let’s consider duration for a moment as this is the number that goes through everyone mind when they consider the cam size. In reality it is the LCA that dictates how successfully the engine makes torque and the overlap selected that determines where in the RPM range peak torque will occur.

Let’s say that we know from our computations that a 108 LCA is optimum and that 80 degrees of overlap will put peak torque in the rpm range we want with the engine hardware at our disposal. If we know what the LCA is and the overlap there is only one duration figure that fits. With the example two numbers the duration of this (single pattern) cam will be the LCA plus half the overlap and the sum of those two angles times 2 will give you the duration i.e. 2(108 + (80/2))= 296. So we have backed into the duration required Rather than starting with it as an entity which determines the operating rpm range. It does affect it but only by virtue of the combination of the LCA and the overlap. In other words it is more of a result than a determinant.


There's more to this although I'm sure you've read the entire paper. This approach is very intriguing. A if the author's credentials and decades of testing are of any relevance, a very sound method of selecting a cam.

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Re: CID/RPM/CFM/HP

Post by vortecpro » Sun Nov 05, 2017 8:55 pm

Get it over with and just go power adder, you are a power adder guy...............
Racing a NA NHRA stocker should be mandatory before any posting.

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Re: CID/RPM/CFM/HP

Post by zums » Sun Nov 05, 2017 9:26 pm

skinny z wrote:
Sun Nov 05, 2017 8:54 pm
randy331 wrote:
Sun Nov 05, 2017 10:15 am
skinny z wrote:
Sun Nov 05, 2017 10:06 am


So, is that to say that a 110 LSA will not be significantly different in power and torque than one with 106 LSA provided the overlap remains the same?
In my experience no. At least not if both cams are of the same lobe family ( lobe speed and lift ) and installed on the same ICL. I think a lot of these types of changes just get cams put in as the cam card shows, so the 106 ends up advance and the engine likes the earlier IVC point and people see that and think it's the LSA that made the difference.

IVC seems to run the show for the most part.

Randy
An excerpt from a well respected engine builder.

A 108 Lobe Centerline Angle (also called a Lobe Separation Angle) for this particular engine (a 355 SBC with 186 heads and a 10/1 CR gave the widest and best output on a 108 LCA. Spread that angle and watch the torque and HP drop.

Let’s consider duration for a moment as this is the number that goes through everyone mind when they consider the cam size. In reality it is the LCA that dictates how successfully the engine makes torque and the overlap selected that determines where in the RPM range peak torque will occur.

Let’s say that we know from our computations that a 108 LCA is optimum and that 80 degrees of overlap will put peak torque in the rpm range we want with the engine hardware at our disposal. If we know what the LCA is and the overlap there is only one duration figure that fits. With the example two numbers the duration of this (single pattern) cam will be the LCA plus half the overlap and the sum of those two angles times 2 will give you the duration i.e. 2(108 + (80/2))= 296. So we have backed into the duration required Rather than starting with it as an entity which determines the operating rpm range. It does affect it but only by virtue of the combination of the LCA and the overlap. In other words it is more of a result than a determinant.


There's more to this although I'm sure you've read the entire paper. This approach is very intriguing. A if the author's credentials and decades of testing are of any relevance, a very sound method of selecting a cam.
You read too many bullshit magazines
Tom

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Re: CID/RPM/CFM/HP

Post by skinny z » Sun Nov 05, 2017 9:32 pm

[quote=zums post_id=697188 time=1509935166 user_id=6117]
[quote="skinny z" post_id=697178 time=1509933249 user_id=6881]

You read too many bullshit magazines
Tom
[/quote]

You should check your facts before commenting.

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Re: CID/RPM/CFM/HP

Post by randy331 » Sun Nov 05, 2017 9:33 pm

skinny z wrote:
Sun Nov 05, 2017 8:54 pm
There's more to this although I'm sure you've read the entire paper. This approach is very intriguing. A if the author's credentials and decades of testing are of any relevance, a very sound method of selecting a cam.
No , can't say I've read it, or care to.

Randy

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Re: CID/RPM/CFM/HP

Post by skinny z » Sun Nov 05, 2017 9:45 pm

So, to wrap this up, I can say that I've learned something.
Thanks for all of the contributions. The subject material is starting to get spread around and it wasn't my intention to have go that way. I kind of wanted to keep it on point but at the very least, my questions have been answered.
Thanks again.

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