Another "How much will it make?" Project "Special Needs"

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Re: Another "How much will it make?" Project "Special Needs"

Post by CGT » Tue Aug 15, 2017 9:08 pm

Warp Speed wrote:I like the comp intake lobe and the bullet exhaust lobe on a 108, in at 107ish! LOL 8)
I kinda of tend to agree. Couldn't find an intake lobe like the Comp at Bullet, or a similiar exhaust lobe as the Bullet at Comp.
The original cam didnt respond to advancing like we figured, so it was possibly pushing the EVO too early for the beginning of the pull.....maybe
It will be fun to sort through the data after its done. Thanks for the comments Jay. The goal of the new cam is to be better everywhere in the pull. 3000 to 7000.

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Re: Another "How much will it make?" Project "Special Needs"

Post by MadBill » Tue Aug 15, 2017 9:15 pm

Just in general, a cam that is unresponsive to indexing has one or more events significantly sub-optimized. In other words, a well-specced cam will lose significant power from its best index when advanced or retarded by only a couple of degrees.
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Re: Another "How much will it make?" Project "Special Needs"

Post by CGT » Tue Aug 15, 2017 9:48 pm

MadBill wrote:Just in general, a cam that is unresponsive to indexing has one or more events significantly sub-optimized. In other words, a well-specced cam will lose significant power from its best index when advanced or retarded by only a couple of degrees.
Thanks Bill. I agree but have seen exceptions. This cam definitely responded to not being run earlier than 110icl. Which put it at a later ivc than this induction has made best power on other combos.

As long as all those lobes are attached to the same camshaft, questions are raised at the same rate they are answered it seems lol. I just like the process of sorting through it i guess.

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Re: Another "How much will it make?" Project "Special Needs"

Post by randy331 » Sat Aug 19, 2017 12:55 pm

MadBill wrote:In other words, a well-specced cam will lose significant power from its best index when advanced or retarded by only a couple of degrees.
I disagree.

Randy

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Re: Another "How much will it make?" Project "Special Needs"

Post by MadBill » Sat Aug 19, 2017 4:13 pm

So, what's been your experience and explanation for the results?
The last indexing test I witnessed was a 572" Hemi with a custom LSM cam, the result of several iterations of development in similar spec engines. It was initially installed per LSM's spec (4°A). Advancing 2° more lost 8 HP. Retarding 4° to zero gained 20.
It seems logical that if all the events are correct, A or R will leave them all sub-optimal and so lose power, whereas if for example two are over-advanced and two retarded, as the cam is advanced or retarded the changes will tend to cancel out, leaving the engine largely indifferent to indexing.

Update: Here's a quote from David Vizard on the subject: "If cam events are virtually optimal on the cam then timing the cam correctly becomes more important. If events are not "right on" then we find that retiming the cam may put one event nearer optimal while others move away from optimal. Under these circumstances retiming the cam only produces marginal changes. These may show a certain advantage in one part of the rpm range at the expense of another.

However if the cam is capable of delivering optimal valve events in every respect we find the cam becomes much more sensitive to timing. An error in timing means that all events are now displaced from optimum. The result is that the engine can lose output everywhere over its entire working rpm band."
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Re: Another "How much will it make?" Project "Special Needs"

Post by randy331 » Sun Aug 20, 2017 11:42 am

First, the idea that you can have " optimal cam events through out the rpm band " is a fictitious idea.

Take the engine in this thread. it's being pulled from 3000-7000 and some pulls from 3000-7500. You can't have it optimal all the way through there.
What's optimal from 3000-4000 isn't for 6000-7000. All you can do is find an acceptable compromise, and that compromise will cost it power somewhere. And as you move the compromised cam around it's very likely those events will result in trade offs when the cam is moved around, because all the events aren't gonna need to be moved the same direction, the same amount as rpm changes through the pull. Even valve speed is part of the compromises. To have the valve train good at 7500 rpm, you cost it power at 3000 rpm.

I was just in on a dyno session with flat tappet cam. After break in we made a couple full pulls with break in rockers before switching to the race rockers. The change netted 50 HP up top, only 10 ish more LBs peak TQ but the higher ratio rockers hurt the start of the pull. Clearly it liked the lift/area up top but not at the start. So how do you optimize that through out the rpm band ? Less duration with even more lift/area ? That would likely help the bottom end but hurt the top. And there are limits to valve velocity/acceleration which also play into valve events.

So to me a cam not having a big power drop when moved around is as likely a sign of good compromises for the rpm band as it is a sign it's all wrong.

So, I still disagree.

Randy

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Re: Another "How much will it make?" Project "Special Needs"

Post by Walter R. Malik » Sun Aug 20, 2017 12:00 pm

randy331 wrote:First, the idea that you can have " optimal cam events through out the rpm band " is a fictitious idea.

Take the engine in this thread. it's being pulled from 3000-7000 and some pulls from 3000-7500. You can't have it optimal all the way through there.
What's optimal from 3000-4000 isn't for 6000-7000. All you can do is find an acceptable compromise, and that compromise will cost it power somewhere. And as you move the compromised cam around it's very likely those events will result in trade offs when the cam is moved around, because all the events aren't gonna need to be moved the same direction, the same amount as rpm changes through the pull. Even valve speed is part of the compromises. To have the valve train good at 7500 rpm, you cost it power at 3000 rpm.

I was just in on a dyno session with flat tappet cam. After break in we made a couple full pulls with break in rockers before switching to the race rockers. The change netted 50 HP up top, only 10 ish more LBs peak TQ but the higher ratio rockers hurt the start of the pull. Clearly it liked the lift/area up top but not at the start. So how do you optimize that through out the rpm band ? Less duration with even more lift/area ? That would likely help the bottom end but hurt the top. And there are limits to valve velocity/acceleration which also play into valve events.

So to me a cam not having a big power drop when moved around is as likely a sign of good compromises for the rpm band as it is a sign it's all wrong.

So, I still disagree.

Randy
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Re: Another "How much will it make?" Project "Special Needs"

Post by MadBill » Sun Aug 20, 2017 12:09 pm

You're shifting the goalposts there Randy. Neither the engine in my example nor I'm sure in DV's remarks, were targeted at a 4,500 RPM power band. In fact for the former, with a very high stall converter, it was more like 6,500 to 8,500 and was to be launched at well over peak torque. Indexing effects below say 6,000 were totally irrelevant.
My hat's off to guys that can wring out top end power within the straightjacket of EMC rules, but such engine are not optimal for many forms of racing.
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Re: Another "How much will it make?" Project "Special Needs"

Post by randy331 » Sun Aug 20, 2017 12:27 pm

MadBill wrote:You're shifting the goalposts there Randy. Neither the engine in my example nor I'm sure in DV's remarks, were targeted at a 4,500 RPM power band. In fact for the former, with a very high stall converter, it was more like 6,500 to 8,500 and was to be launched at well over peak torque. Indexing effects below say 6,000 were totally irrelevant.
My hat's off to guys that can wring out top end power within the straightjacket of EMC rules, but such engine are not optimal for many forms of racing.
Not moving the goal post at all. You posted a cam being un-responsive is a sign the cam is wrong, on this thread, in which the engine is being pulled from 3000-7000 and on up to 7500 some. I posted my reasons for disagreeing.

By the way SN isn't an EMC engine. It's headed for a street car if it survives all the dyno time. LOL

As far as the results from your cam test, (if that's what your asking) would suggest to me IVC is the reason. IVC seems to run the show a lot.
The one other thing could be overlap position VS piston position. I've seen some evidence to suggest when it's too much overlap or not enough the position of it is a little more picky.

Randy

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Re: Another "How much will it make?" Project "Special Needs"

Post by CGT » Mon Aug 28, 2017 12:39 pm

Resized_20170825_183807.jpeg
Almost dyno ready for anyone interested.
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Re: Another "How much will it make?" Project "Special Needs"

Post by cjperformance » Mon Aug 28, 2017 7:44 pm

Ah good stuff, time for some revs!
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Re: Another "How much will it make?" Project "Special Needs"

Post by steve316 » Tue Aug 29, 2017 8:51 am

I am ready for the dyno results, so let the big dog eat. :D

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Re: Another "How much will it make?" Project "Special Needs"

Post by Carnut1 » Tue Aug 29, 2017 9:11 am

Interested in the oiling system of this engine. Chevys are better at rpm with a small or stock sump pan but Smallblock Fords that rev 7000 rpm with a stock pan and hv pump are problematic at pumping the pan dry and seizing the oil pump and drill bitting the oil pump shaft. Learned that the hard way. Thanks, Charlie
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Re: Another "How much will it make?" Project "Special Needs"

Post by CGT » Tue Aug 29, 2017 12:02 pm

Carnut1 wrote:Interested in the oiling system of this engine. Chevys are better at rpm with a small or stock sump pan but Smallblock Fords that rev 7000 rpm with a stock pan and hv pump are problematic at pumping the pan dry and seizing the oil pump and drill bitting the oil pump shaft. Learned that the hard way. Thanks, Charlie
Stock late model 4.3 v6 pump taken from a low mileage core, bead blasted gears and housing, filed housing to close up gear to cover clearance up some, a little deburring and chamfering and in it went. I liked the pump because it was small, yet had the larger 3/4 inlet. The block has just had typical deburring, removing slag and contouring around oil returns.
Last edited by CGT on Tue Aug 29, 2017 12:15 pm, edited 1 time in total.

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Re: Another "How much will it make?" Project "Special Needs"

Post by Carnut1 » Tue Aug 29, 2017 12:06 pm

CGT wrote:
Carnut1 wrote:Interested in the oiling system of this engine. Chevys are better at rpm with a small or stock sump pan but Smallblock Fords that rev 7000 rpm with a stock pan and hv pump are problematic at pumping the pan dry and seizing the oil pump and drill bitting the oil pump shaft. Learned that the hard way. Thanks, Charlie
Stock late model 4.3 v6 pump taken from a low mileage core, bead blasted gears and housing, filed cover to close up gear to cover clearance up some, a little deburring and chamfering and in it went. I liked the pump because it was small, yet had the larger 3/4 inlet. The block has just had typical deburring, removing slag and contouring around oil returns.
Is that pump smaller than a stock smallblock pump? Thanks, Charlie
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