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Dart 180 cc alloy head as cast

General engine tech -- Drag Racing to Circle Track

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steve cowan
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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Tue Nov 26, 2019 7:29 pm

CGT wrote:
Tue Nov 26, 2019 3:11 pm
Steve...your thread may or may not be your thread anymore :lol:
Chad,
I am enjoying the conservation, the whole thread has been educational for me :D
steve c

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Re: Dart 180 cc alloy head as cast

Post by randy331 » Tue Nov 26, 2019 8:23 pm

Stan Weiss wrote:
Tue Nov 26, 2019 12:19 pm
Just what kind of dyno testing do you do? Are you using a inertia type dyno which lets the engine have a variable acceleration rate like it will on a drag strip or the standard 300 or 600 rpm per second tests?
Stan
It was at about 600 rpm per second acceleration sweep rate on a Stuska dyno (with an inertia factor :D ).
The Stuska dynos aren't a set fixed acceleration rate. The sweep rate may average 600 rpm per sec. but it will vary some with the tq level.

Do you think the results would be different on a different type dyno ?

The pulls were laying right over one another before the change in rocker ratio.
I've learned to make back up pulls on most changes to validate the results.
In the time it takes to swap out a shaft rocker system the oil will cool off some and the only way to put temp back in the oil on an engine with this type of ring pac is to pull it.

Randy

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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Wed Nov 27, 2019 3:59 am

steve cowan wrote:
Tue Nov 26, 2019 12:08 pm
Randy,
i just re-read the 2017 EMC thread again,great thread
interesting chat about oil pump and pressure,vac pumps and oil pans,really enjoyed the read and also read the magazine article on your 2011 383 that made 606hp.
on the 2017 emc thread one of your closing statements was-
ONE OVERLOOKED FACTOR IN MAKING POWER AT EMC TYPE RPM IS LACK OF DEPRESSION NOT LACK OF CFM.
can you expand on this -
2 x thoughts-testing at higher depressions??
or feeding the cylinder faster in first half of induction stroke due to rpm,lift rules etc
just thinking out loud :?:
steve c

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Re: Dart 180 cc alloy head as cast

Post by randy331 » Wed Nov 27, 2019 9:32 am

steve cowan wrote:
Tue Nov 26, 2019 12:08 pm
Randy,
i just re-read the 2017 EMC thread again,great thread
interesting chat about oil pump and pressure,vac pumps and oil pans,really enjoyed the read and also read the magazine article on your 2011 383 that made 606hp.
on the 2017 emc thread one of your closing statements was-
ONE OVERLOOKED FACTOR IN MAKING POWER AT EMC TYPE RPM IS LACK OF DEPRESSION NOT LACK OF CFM.
can you expand on this -
It's really time based. Down at 3000 or 4000 rpm it isn't hard to supply air to an engine, it's harder to create depression.

Randy

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Re: Dart 180 cc alloy head as cast

Post by brentry » Thu Nov 28, 2019 1:57 pm

SpeierRacingHeads wrote:
Mon Nov 25, 2019 10:41 am
PRH wrote:
Mon Nov 25, 2019 10:34 am
Maybe I’m not being analytical enough, and just going by what I “think” the results would be.
But here’s how I see it......
Chads heads have already shown they can make 675hp on a 383.

Not trying to take anything away from Steve’s efforts here, but if he ends up with what he says he’s shooting for......which is starting out with a Dart SHP 180 head, doing some rework to arrive at 270-280cfm with a finished runner volume in the 200-ish cc range....... and you removed the SRH 205’s from that 675hp 383 and swapped them for Steve’s Dart’s....... I’d be expecting the motor to take a pretty big hit in the HP dept.
Chris Cobb has a 383 in the works right now and the goal is 700.. I will be sure to post it up so the house mafia can pick it apart.
700 @ what rpm?

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Re: Dart 180 cc alloy head as cast

Post by digger » Thu Nov 28, 2019 4:43 pm

IMO it comes down to efficiency (discharge coefficient) at low rpm as the port might be be designed to move air for maximum power at 6500 rpm but at 3000 rpm its effectively way too large.

at 'low' rpm a larger size, higher flowing head will mean less depression (less resistance to flow) on the running engine but its got more area. so does the the smaller depression acting on larger area create more mass flow?

or does a smaller size lower flowing head that results in a higher depression (more Resistance to flow) acting on a smaller area result in more mass flow?

so if the larger port is 10% larger how much less depression will it see for the same operating point, rate of change of swept volume etc? 5% 10% 20%?

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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Thu Nov 28, 2019 5:11 pm

Both ports may have same mass flow until the pressure in the cylinder is greater than the Port starting reversion,
This is where the smaller port can help overfill the cylinder producing 100% plus VE but valve timing events will dictate this to a point.
This is where cfm/in2 of pinch,throat, valve becomes important.
I can't answer second part of question :D
Sorry Digger
steve c

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Re: Dart 180 cc alloy head as cast

Post by CGT » Thu Nov 28, 2019 7:24 pm

digger wrote:
Thu Nov 28, 2019 4:43 pm
IMO it comes down to efficiency (discharge coefficient) at low rpm as the port might be be designed to move air for maximum power at 6500 rpm but at 3000 rpm its effectively way too large.
I can agree with this. Or even possibly a head that is slightly undersized for your "6500" rpm target meeting it by means of very good discharge coefficient. But what part of the port do you focus this dc at? Throat, window, window at what lift, pinch if not at throat? Getting it real high in one of these areas will most likely compromise it elsewhere in the port.

One thing i think is for sure. Your not going to cam an engine with too big of a head to be outstanding down there at 3 and 4 thousand....unless your just looking for very average power everywhere.
"Never let your hobby ride you. Work while you work and play while you play"

"Hobbies are a contradiction; they take work and turn it into leisure, and take leisure and turn it into work."

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Re: Dart 180 cc alloy head as cast

Post by midnightbluS10 » Thu Nov 28, 2019 8:16 pm

steve316 wrote:
Mon Nov 25, 2019 11:21 am
Chad aren't you a member of the house mafia?
Seems like you're not grasping what he's saying by this comment. How can he be part of something that actively bashes him whenever possible? The disdain they have for him is quite clear cut. <shrug>
JC -

SUPPORT THE RPM ACT :!:

https://www.sema.org/rpm-bill-summary

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Re: Dart 180 cc alloy head as cast

Post by steve316 » Thu Nov 28, 2019 9:26 pm

Well s10 I guess you have never heard of the pot calling the kettle black.

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Re: Dart 180 cc alloy head as cast

Post by randy331 » Thu Nov 28, 2019 9:36 pm

digger wrote:
Thu Nov 28, 2019 4:43 pm
IMO it comes down to efficiency (discharge coefficient) at low rpm as the port might be be designed to move air for maximum power at 6500 rpm but at 3000 rpm its effectively way too large.

at 'low' rpm a larger size, higher flowing head will mean less depression (less resistance to flow) on the running engine but its got more area. so does the the smaller depression acting on larger area create more mass flow?

or does a smaller size lower flowing head that results in a higher depression (more Resistance to flow) acting on a smaller area result in more mass flow?

so if the larger port is 10% larger how much less depression will it see for the same operating point, rate of change of swept volume etc? 5% 10% 20%?
This is the direction I was thinking my post/questions would head.

If I had all these answers I'd post them. LOL :D

I figure Steve is like a lot of us on here, we don't have all the answers and are always wondering how we could make what we build better and, therefore he wouldn't mind the "slight" deviation from his original post. :D

Randy

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Re: Dart 180 cc alloy head as cast

Post by Elroy » Thu Nov 28, 2019 10:58 pm

Well this is all new to me but.//information is good///its free information on the internet from what im seeing at my age but be careful what you absorb and attempt to transfer to your project//use to be word of mouth///its your job to decipher and take from the results given to you////examples given of "205" heads despite math suggesting otherwise///makes it hard for comparisons////confusing to me why lie being old school.///good info on the net but be careful of marketing /nothing has changed still deliberate disinformation////up to you if you wanna use previous examples to wade through the politics..
Im old and a retired analyst so to speak//. In my career pointing out falsehoods and disinformation was a daily duty//. its come to me quickly that the internet hasn't just given voice to good examples with facts///but also bad. same shit different venue//. People are people/ follow the money, doesnt even have to be alot of it.

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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Thu Nov 28, 2019 11:40 pm

Elroy,
I think you would have a lot to contribute on this thread, I enjoy the information you have shared on dyno testing,
There are some people here that have there finger on the pulse so to speak.
Alot of this is way beyond my experience level, but I am here to learn. :D
steve c

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Re: Dart 180 cc alloy head as cast

Post by Stan Weiss » Fri Nov 29, 2019 2:30 am

digger wrote:
Thu Nov 28, 2019 4:43 pm
IMO it comes down to efficiency (discharge coefficient) at low rpm as the port might be be designed to move air for maximum power at 6500 rpm but at 3000 rpm its effectively way too large.

at 'low' rpm a larger size, higher flowing head will mean less depression (less resistance to flow) on the running engine but its got more area. so does the the smaller depression acting on larger area create more mass flow?

or does a smaller size lower flowing head that results in a higher depression (more Resistance to flow) acting on a smaller area result in more mass flow?

so if the larger port is 10% larger how much less depression will it see for the same operating point, rate of change of swept volume etc? 5% 10% 20%?
Not sure if this is what you are talking about. This is still a work in progress. The cfm is the peak piston flow demand at the listed RPM and the speeds / DC for the different places.

Stan

Code: Select all


_____Intake_______---_Throat_--____----_Valve_---____----_MCSA_----__----_CFM_per_Sq._In._----_
__RPM____CFM______fps_______DC______fps_______DC______fps_______DC____Throat____Valve____MCSA_
2000.0___77.1___72.229___0.2062___57.748___0.1649___74.366___0.2123___30.095___24.062___30.986
2500.0___96.4___90.286___0.2577___72.185___0.2061___92.957___0.2654___37.619___30.077___38.732
3000.0__115.7__108.343___0.3093___86.622___0.2473__111.548___0.3184___45.143___36.093___46.478
3500.0__134.9__126.400___0.3608__101.059___0.2885__130.140___0.3715___52.667___42.108___54.225
4000.0__154.2__144.457___0.4124__115.496___0.3297__148.731___0.4246___60.190___48.123___61.971
4500.0__173.5__162.514___0.4639__129.933___0.3709__167.323___0.4777___67.714___54.139___69.718
5000.0__192.8__180.571___0.5155__144.370___0.4121__185.914___0.5307___75.238___60.154___77.464
5500.0__212.1__198.628___0.5670__158.807___0.4533__204.505___0.5838___82.762___66.170___85.211
6000.0__231.3__216.686___0.6186__173.244___0.4946__223.097___0.6369___90.286___72.185___92.957
6500.0__250.6__234.743___0.6701__187.681___0.5358__241.688___0.6900___97.809___78.201__100.703
7000.0__269.9__252.800___0.7217__202.118___0.5770__260.280___0.7430__105.333___84.216__108.450
7500.0__289.2__270.857___0.7732__216.555___0.6182__278.871___0.7961__112.857___90.231__116.196
8000.0__308.4__288.914___0.8248__230.992___0.6594__297.462___0.8492__120.381___96.247__123.943
8500.0__327.7__306.971___0.8763__245.429___0.7006__316.054___0.9022__127.905__102.262__131.689
9000.0__347.0__325.028___0.9279__259.866___0.7418__334.645___0.9553__135.429__108.278__139.435
9500.0__366.3__343.086___0.9794__274.303___0.7831__353.236___1.0084__142.952__114.293__147.182

Avg_____221.7__207.657___0.5928__166.026___0.4740__213.801___0.6103___86.524___69.177___89.084
Stan Weiss / World Wide Enterprises
Offering Performance Software Since 1987
Do you use engine simulation software that uses cylinder head flow files?
We have a package of more than 3025 DFW or FLW Files

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Re: Dart 180 cc alloy head as cast

Post by GARY C » Fri Nov 29, 2019 3:21 am

digger wrote:
Thu Nov 28, 2019 4:43 pm
IMO it comes down to efficiency (discharge coefficient) at low rpm as the port might be be designed to move air for maximum power at 6500 rpm but at 3000 rpm its effectively way too large.

at 'low' rpm a larger size, higher flowing head will mean less depression (less resistance to flow) on the running engine but its got more area. so does the the smaller depression acting on larger area create more mass flow?

or does a smaller size lower flowing head that results in a higher depression (more Resistance to flow) acting on a smaller area result in more mass flow?

so if the larger port is 10% larger how much less depression will it see for the same operating point, rate of change of swept volume etc? 5% 10% 20%?
I think the difficulty of answering these questions is that for any example given someone else can give an example that is counter to what one thinks is best, at least in actual on track performance, the dyno may say something different, not sure how much one truly reflects the other.
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