4age 16v split cams setup

xploding-twincam
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4age 16v split cams setup

Postby xploding-twincam » Wed May 01, 2013 11:41 pm

Hi Guys
Im thinking of running split cam setup on my small port,
correct me if im wrong with my setup
272deg int and 264deg exh and lift above 8mm
Is this fine?
and im confused about which cam should be bigger???intake is the common due to it allowing more air into the motor???

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Re: 4age 16v split cams setup

Postby ga_goosh » Thu May 02, 2013 5:11 am

if you put the bigger cam on the exhaust it will help to evacuate exhaust fumes faster and more efficiently. the exhaust side of the 4ag head is more restrictive then the intake side
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Re: 4age 16v split cams setup

Postby xploding-twincam » Thu May 02, 2013 5:19 am

So better to run more lift on the exhaust side?

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oldeskewltoy
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Re: 4age 16v split cams setup

Postby oldeskewltoy » Sat May 04, 2013 2:42 pm

mixing cam durations:
Good: "allows" for tuning of either intake flow or exhaust flow depending on which causes more of a problem.

Bad: often times mixing durations doesn't allow for peak performance from either cam.

272 and 264... what are you using for management?
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Re: 4age 16v split cams setup

Postby xploding-twincam » Wed May 08, 2013 9:24 am

oldeskewltoy wrote:mixing cam durations:
Good: "allows" for tuning of either intake flow or exhaust flow depending on which causes more of a problem.

Bad: often times mixing durations doesn't allow for peak performance from either cam.

272 and 264... what are you using for management?


After market ecu - currently using Go-tec but will be moving onto Dicktator,

Im also looking for a good mid rang peak power at 7500prm.

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Re: 4age 16v split cams setup

Postby 8Ton » Wed May 08, 2013 2:18 pm

Correct me if I am wrong but I was under the impression that longer duration and lift on the intake side created more torque and mid range (possibly at the expense of peak HP) and was more commonly done on the 4ag. it appears that TRD used this for some of it's rally setups.

I think that the dsm guys do more on the exhaust side, but they have turbos....

What are you using the engine for? A race boat has Much different needs than a DD street car. Also what compression are you running? I feel that 272 cams are best left to race cars. For my street smallport with 11-1cr I am using 250ish 8+ lift for the intake and stock 232 7.1s on the exhaust.

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Re: 4age 16v split cams setup

Postby oldeskewltoy » Wed May 08, 2013 3:54 pm

research "dynamic compression ratio"


while maintaining static compression - longer duration cams on the intake side usually lowers torque by having an intake valve closing event happen later then a shorter duration cam.
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: 4age 16v split cams setup

Postby 8Ton » Wed May 08, 2013 5:57 pm

well there goes my plans for the night! I liked it better when I thought I was right.

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Re: 4age 16v split cams setup

Postby xploding-twincam » Thu May 09, 2013 11:44 am

Looking at short term - TRD HG to bump comp and use the car for street racing,
Long term Sc12 - with 4agze 9 comp pistons

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Re: 4age 16v split cams setup

Postby 8Ton » Fri May 10, 2013 7:54 am

I Couldn't find a whole lot of info on twin cams with split durations except this http://www.eng-tips.com/viewthread.cfm?qid=313042
Oldschool v8s usually do more duration on the exhaust so this may not be totally on point for us, but to some point an engine is an engine.

Isky says longer exhaust duration cams simply kill low-mid range torque and no more...and that single pattern cams alway make more power...

"...Why is it that so many people (racers & cam grinders alike) insist on running a cam with longer exhaust duration regardless of what equipment is employed? The answer is "habit". Most of them have been somewhat successful in doing it their way and will probably never change unless virtually forced by circumstances to do so.

Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!

Example #1 (Oval track racing) Here, I have often observed that the most experienced drivers are those who are most likely to run a single pattern (equal on intake and exhaust duration) cam. Why? Because such cams always, I repeat always make more torque! These veterans have a more educated foot and greater experience in feathering the throttle in the corners. They can therefore, utilize the benefit of added torque, in the lower to mid RPM range, to their advantage.

Their counterparts, the younger drivers on the circuit, generally are not as experienced and may at times actually get "crossed up" in the corners especially with a lighter car or when they are learning the ropes. In their case, a longer exhaust duration is often the more appropriate choice. It will often help them to drive better, more "flat footed" if you will, without consequence. But please for the sake of accuracy, let us be truthful. The benefit comes from an actual bleeding off of low to mid range torque, which is always what happens when Exh. Duration is lengthened, not from any improvement. The improvement, (if any) would come because of an improvement in scavenging at the extreme upper end of the power curve and would usually be marginal at best. Yet the so-called "extra power" potential of a longer Exh. Duration cam is most often why they are touted - power most people are backing away from at the end of the strait away!

Example #2 (Drag Racing) At the drag strip it's a little different and I feel more honest. Here, racers have long enjoyed longer exhaust and longer durations across the board (If I may add specifically for the purpose of "killing" low-end torque) to keep the tires from too easily breaking lose. This has been successful and sometimes actually results in a slight increase in top end power - something you can actually use in drag racing since it is a full throttle endeavor through the lights. Keep in mind here though, it's quite possible that a longer duration cam overall would have done just as well or better. In other words if you needed that longer exhaust for top end, perhaps the intake could have benefited from such a lengthening as well. ..."

As far as good street grinds for our engines, look up "why turbo that" he did a lot of dyno testing and also had lots of over camming problems with what are usually considered 'street grinds'
I would stick to 256 or less personally.

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Re: 4age 16v split cams setup

Postby oldeskewltoy » Fri May 10, 2013 9:21 am

8Ton wrote:Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!


These are called pumping losses... and pumping losses are why a well ported head is often times more desirable then a camshaft upgrade....

Image

the little red arrows are pointing to 7.1mm lift, or cams from 1988+ 4AGE engines

the blue arrows are 7.5mm lift from the earlier pre 1988 4AGE engines

As the arrows show even with stock cams, port work improves flow.
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: 4age 16v split cams setup

Postby 8Ton » Fri May 10, 2013 7:20 pm

Thanks for posting the chart, it is VERY informative! Was this test from a small port or large port? Its amazing how little flow is gained with higher lifts on the exhaust, even with the port work. It just levels off by 7mm. Would you think that this is because valve size?
Considering that cams run $300+ each, springs are around $160 and cam gears are $160+ , It would seem that the best bang for your $ would be to pull the head and have it ported and a good valve job and leave the cams stock.
So for the sake of this argument, lets assume that an appropriate amount of headwork and compression has been taken care of. But I don't see how it points to longer durations on the intake side bleeding off torque. Even researching dynamic compression I saw that it would lower the DCR, but not kill torque more than 'twin' cams with the same duration.
Not trying to split hairs, but I have a pair of cams waiting to be custom cut in the next day or so (they didn't call today, so next week I suppose) So this is extremely relevant to me.

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Re: 4age 16v split cams setup

Postby oldeskewltoy » Fri May 10, 2013 9:51 pm

8Ton wrote:Thanks for posting the chart, it is VERY informative! Was this test from a small port or large port? Its amazing how little flow is gained with higher lifts on the exhaust, even with the port work. It just levels off by 7mm. Would you think that this is because valve size?
Considering that cams run $300+ each, springs are around $160 and cam gears are $160+ , It would seem that the best bang for your $ would be to pull the head and have it ported and a good valve job and leave the cams stock.
So for the sake of this argument, lets assume that an appropriate amount of headwork and compression has been taken care of. But I don't see how it points to longer durations on the intake side bleeding off torque. Even researching dynamic compression I saw that it would lower the DCR, but not kill torque more than 'twin' cams with the same duration.
Not trying to split hairs, but I have a pair of cams waiting to be custom cut in the next day or so (they didn't call today, so next week I suppose) So this is extremely relevant to me.


That test is from a largeport head. Valve size WILL have something to do with it, but the exhaust ports I showed are still @ the standard outlet size of 30-31mm, If I open the port out to 33, or 35 volume will increase with the standard valve.

You are correct, the stock port hits a wall @ about 7mm of lift... this is part of the reason Toyota "shrank" the smallport cams from 240 duration to 232, and the lift from 7.5 down to 7.1. As you can see in the chart, correct porting will improve volume both in, and out of the head, even for stock cams.

*IF* you correctly compensate for longer durations, by adding static compression, then you should not lose torque
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: 4age 16v split cams setup

Postby 8Ton » Sat May 11, 2013 10:41 am

oldeskewltoy wrote:*IF* you correctly compensate for longer durations, by adding static compression, then you should not lose torque

Last night I got in bed, and DING I realized that is what you meant!
Do you have flow # for a smallport?

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Re: 4age 16v split cams setup

Postby oldeskewltoy » Sun May 12, 2013 7:21 am

i do not currently have any smallport #s, but the exhaust side should be more or less the same.
OST Cyl head porting, - viewtopic.php?f=22&t=300

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