['74hatchback]

O.K. I ran the data through Desktop dyno basic and Dyno 2000 and of course got slightly different numbers each time. Power band is in the same area though. Most likely, i'm guessing the motor's probably not going to put out as much as either of them says. If anyone can spare a minute, can you give a better estimate? i know some of the parts are not ideal but i need to re-use some of my old stuff untill my pockets fatten back up.

here's the 383(385?) set-up:

-350 block with 3.75 stroke crank and 4.040 bore
figure compression at 10.7 (might be a point or two off but that will work for now)
-Dart Iron Eagle 200cc heads (because my freebee motown 220's fell through)
64cc 2.02./1.6valves. i pulled the flow numbers from this sight:
http://users.erols.com/srweiss/tablehdc.htm

-Holley street dominator high rise dual plane intake (with 2" carb spacer)
-Holley 870cfm street avenger carb
-Comp hyd roller cam XR282HR-10 w/roller lifters
duration @050 230/236
factory lift: .510/.520
110 lobe seperation
-1.6 roller rockers (i know this changes the lift numbers)

Figure open headers with 1 5/8 primaries. I can give more details if necessary.

Dyno2000 gave peak [email protected] and 520TQ at 4000RPM
ProRacing sim(basic) gave 561HP at 6000 and 578TQ at 4000

I'd love to be making 561/578 but i figure thats probably pretty unrealistic. also, those numbers were run with 1.5 rockers instead of the 1.6 i will be using.
If anybody has a different calculation, I'd love to hear it. I only wish i could afford to put it on a real dyno when it's done.
THANKS, -Tim

 

[DriveWFO]

Are you planning on racing or just dynoing the motor and cruisin?



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['74hatchback]

Steet & occasional strip duty. hopefully more than occasional strip duty as the car progresses in the future. Comp says that i should use 2400 stall but that i could get away with my 2100 for time being. Beefed up TH350 with shift kit and hurst ratchet shifter. 373 gears in a 10 bolt. Sub connectors going in also, and a set of slide-a-links as soon as i can afford 'em. plus the million and one other little ideas that are on my drawing board.

so why do you ask? seeing problems? just curious. i was only picking those world heads because they are about as much as i can spend. Although i was going to try for a set of aluminums to help with any possible detonation problems. Any ideas on how to improve? i was pretty dead set on just about everthing but the heads. I plan on switching to an edelbrock RPM Air Gap, but for now, i was just going to re-use my old holley. Also wasn't sure of carb size.

 

[Mike Goble]

EA3.0 sees it like this:

RPM···········2000····2500····3000····3500····4000····4500····5000····5500····6000····6500
Brake_Tq······319·····373·····414·····422·····444·····445·····431·····405·····363·····280
Brake_HP······121·····178·····237·····281·····338·····381·····411·····424·····415·····346
Exh_Pres······.0······.0······.0······.0······.0······.0······.0······.0······.0······.0
Int_Vacuum····.3······.5······.6······.6······.6······.6······.7······.9······1.0·····1.0
Vol_Eff_%·····69.7····77.6····85.1····88.6····94.0····96.8····97.6····96.6····93.6····87.6
Actual_CFM····167·····232·····306·····372·····452·····525·····587·····639·····674·····682
Fuel_Flow·····61.0····84.9····112·····136·····165·····192·····215·····233·····246·····249
A/F_Mix_Qal···100.0···100.0···100.0···100.0···100.0···100.0···100.0···100.0···100.0···100.0
BSFC··········.503····.478····.473····.482····.489····.503····.523····.551····.594····.720
BSAC··········6.305···5.992···5.936···6.051···6.136···6.313···6.556···6.909···7.454···9.032
Friction_HP···22······33······45······60······78······100·····127·····159·····195·····253
Mach_#········.172····.215····.259····.302····.345····.388····.431····.474····.517····.560
Piston_Spd····1250····1563····1875····2188····2500····2813····3125····3438····3750····4063
Piston_Gs·····283·····442·····637·····867·····1133····1433····1770····2141····2548····2991
Overlap_%VE···-4.1····-.5·····2.3·····1.5·····3.2·····3.6·····3.4·····3.0·····2.5·····2.0
Int_AvgVel····114·····142·····170·····199·····227·····256·····284·····312·····341·····369
In_InertiaPrs·.2······.6······1.1·····1.7·····2.1·····2.3·····2.4·····2.3·····2.1·····1.9
In_ResTunPrs··0.0·····0.0·····.0······.0······.0······.0······0.0·····0.0·····0.0·····0.0
Ex_AvgVel·····145·····182·····218·····254·····291·····327·····363·····399·····436·····472
ExTun_Prs·····1.1·····-.2·····-.5·····-.4·····-1.1····-1.7····-1.9····-1.8····-1.4····-1.0
Lifter_Pump_UpNone····None····None····None····None····None····None····None····None····Some
Spark_Adv·····25······26······27······30······31······32······33······33······34······35

 

['74hatchback]

Mike, thanks for running the numbers.
uggg. i guess it was wishfull thinking that i would make the 500 mark and keep it under 6000RPM. It's like opening up your christmas present just to find a pair of socks.

Any thought on what the rest of those numbers mean? For me, it's like looking at a different language. But i'm learning. Can anybody see any detrimental problems in all those other numbers aside form the HP/TQ?

Any ideas on how to improve this setup? I'll definitely be getting a better intake but any thoughts on heads for this combo? Aside from pushrods and rockers, they're the only thing left to buy. My budget for heads is going to be about $700 to $800. I was thinking of going with the Dart Iron Eagle "Platinums" because i can get them off ebay, assembled, for about what my budget allows. Once and a while i see a good deal on Dart aluminum PRO 1's but i haven't had the money when they've popped up. I'd love to get a good set of AFR's but i've never seen them near what my budget would allow. I know the topic of heads has come up on here a bunch so i don't want to push the same debate but i'd like a good out of the box head that i can eventually make even better.

I have a set of 62cc stock heads from a 305 that came bolted on my old 350 but I figured they weren't worth working over but maybe i'm wrong? I just put 'em on ebay but now i'm having second thoughts about keping them. Can they be made to flow really well for a descent price?

 

[Mike Goble]

The friction losses are quite high. You can reduce this by windage control, low friction rings and pistons, reducing accessory drag, roller rockers, etc. The exhaust tuning pressure isn't very high, you could increase this by using a proper length header with a good collector and secondary pipe.

 

['74hatchback]

Cool, thanks for the info Mike. Unfortunately the pistons are alrady in the block so i don't think i'm gonna be switching them. I have a summit stock style oil pan but maybe i can get something with a better windage tray. I have to watch though, my car sits so low in the front that anything more than a stock length oil pan sits a little too close to the ground for comfort. Full roller rockers are gonna be used. And i'm looking into freeing up some horsepower by using an electric water pump and fan, but for now i'm gonna have to use my old belt driven setup. If i re-buy all that stuff, i won't have enough left for descent heads.

As for exhaust, i've got 3/4 length clippsters that will feed into 3" exhaust pipes to a set of "40series" knock off chambered mufflers. also, i have a set of electric cutouts that i got last year but never installed. I didn't use them because my old headers had ground clearance problems. So with the new 3/4 length headers i should be able to tuck the exaust up enough that i don't have to worry about bottomig out and ruining the electric dumps. Is the 3" exhaust and 3/4 headers gonna hurt performance pretty bad?

 

[Mike Goble]

The first thing I would do is sell the electric dumps and invest in a proper exhaust system. You will gain much more by having the physics of the exhaust work with you than the extra noise the dumps will make. The power gained from a well planned exhaust is substantial, and the cost of exhaust tubing is pretty low.

 

[shaggy]

I wouldnt believe the flow numbers from that site either because most of those flow numbers come from the manufacture website which are usually inflated. Most manufactures will defend by saying they usually advertise potential flow numbers not out of the box. I have heard of Dart heads flowing average 30cfm less than advertised.

 

['74hatchback]

anybody got any ideas on the best heads for under $800? Something that will allow me to run my old intake. I'd rather not have to switch to a vortec. Aside from the darts, I was looking at World Motown 220's and Sportsman II's. And also Brodix IK200's, but i have no real world info on any of them. I'm not even sure what specs to look for that will match up with my cam and 383 shortblock. I know i want 64cc or less to keep the compression between 10 and 11. I figured somewhere around 200cc intake runners but i guess that all depends on the flow numbers.

as for the dumps, i was going to set them up so that it would be like running open headers. having the rest of the exaust exit out the angled side of the "Y", putting the dumps in the straight back position. so when they were open, it would be like running open headers. I thought that running open headers was the best exaust possible? I dunno, i'm still learning i guess. I got the dumps as a gift last christmas and i guess i could sell them but i liked the idea of a "tricked out" exhaust. But then again, if it's only eye/ear candy and does more harm than good, whats the use.

......brings a tear to my eye thinkin that i'm not gona be able to do a quick open header rev at the light when one of the local fart can hondas pulls up though.

 

[Stevemc79]

My 230cc Iron Eagle Platinums flowed 284CFM MAX. I had to have mine CNC'd to get the flow numbers where they needed to be ([email protected]). I also had to use offset shaft rockers with my 230's. The standard stud mounted rockers would come off of the valve tip before full lift. Albeit, my cam with 1.6 rockers nets a .712 lift.

If you can save some more money, I would go with a set of AFR's. They flow what they advertise and make great power. The 210cc heads are about $1500. Just my 2 cents

 

['74hatchback]

I'd love to go for a set of AFR's. Everybody's always raving bout them and i figure all the hype ain't for nothing. Only thing is, it would take me at least till the end of summer to save up the extra $800. I check ebay for them all the time. Hopefully a good set will pop up at a price I can afford but it's a waiting game. If nothing comes up in the next 6 weeks i'll end up with whatever i can get. I just read some posts that said World sportsmans were a descent bang for the buck and i see them in my price range all the time. I'll hold out untill the last minute for a deal on AFR's but I'm determined to get te car on the road this summer. I didn't even get to put a 100 miles on it last summer and I'll go crazy if the same thing happens again.

AFR's MUST be good because anybody that has them, ain't parting with them. "you can have my AFR's when you can pry my cold dead hands off em"