Printable View
I'm 2 days away from having my short block together for the el camino. I'm getting really antsy to see what she'll do at full strength.
For a little sneak peak, could someone with a good version of desktop dyno tell me what you need to know in order to give me a fairly accurate hp/tq rating. Thanks a bunch.
motor type, cubic inches, cylinder head type, valve sizes, port work?, exhaust type, header size, with/without mufflers, cam lifter type, cam lift, duration, intake type, carb type and size, compression ratio. That would be the basics for a start.
George
Motor Type: Small block Chevy
Cubic Inches: 377 CID
Cylinder Head: '441 Casting Iron heads 76cc Combustion Chambers
Valves: 2.02/1.60
Exhaust: 3 inch 'X' pipe
Headers: Yes, not sure on size though.
Mufflers: Yes, 40 series flowmaster
Cam: Solid Roller, ".567/".567 int/exh 242/242@.050
Intake: Edelbrock Torker II Intake
Carb Type: Not sure, possibly looking at 750cfm holly double pumper or demon
Compression Ratio: estimated @ 10:1
The pistons are Probe forged flat top. The rods are forged 'H' beam. The crank is Scat cast steel. Block is 4 bolt 400 SBC. Cam is Chet Herbert Performance. Valve train is Renegade Racing. Cam is on a 110 degree lobe center.
I appreciate anyone who will take the time to help me out here. If you need anymore information, just ask. I will provide :)
sounds to me like its gonna be quite the monster :eek:Quote:
Originally Posted by Hopper111
Hopper, here's what I got. I had to make a few assumptions (intake centerline =106*, large tube headers, 4" bore, 3.75" stroke = small bore 383?).
381HP @5000, 479lbft @ 2000-2500
Seems a solid roller might be overkill for low revs :confused: Could probably get as good performance out of a good hydraulic...
Your heads are holding you back. With that much cam, you need a set of good breathing aluminum heads like AFR or Brodix to make your combination work to its full potential.
I'm sorry, i did not specify bore and stroke. It's a 4.155 bore x 3.5 stroke
Destroked 400 SBC. The cam is a 110* lobe center.
What would the numbers be if i swapped over to a good set of AFR or Brodix heads?
I used destop dyno 2000 and got very different results for some reason.
I also had to try to fit your specs into the program parameters(that leave a bit to be desired). I used 4.155 bore, 3.5 stroke, solid roller .567 lift, 296 int dur, 302 exh dur, 106 lobe centers, 87 deg valve overlap, large tube headers w/ mufflers, "low performance, pocket ported" heads with 2.02, 1.60 valves. 10.1 comp. etc, etc.
here is what I got...
rpm hp tq
2000 106 279
3000 186 326
4000 307 403
5000 423 444
5500 457 436
6000 477 418
6500 483 390
7000 470 353
7500 454 318
Big difference...I went back and checked to see if I missed something obvious. Didn't see anything. Then again I'm known for not being able to see the milk in the fridge! For what I put in, that's what DD2000 spit out. For the motors sake, I sure how my numbers are closer!!!
Hope this brightens your day a bit.
Can someone else out there give it a run to get a third opinion...it shouldn't be that different! I'm probably the one screwing it up here...sniffed too much race gas...or was it glue...what's my name again?
For the record, I do agree that your heads would represent your most obvious bottleneck in the power department. I suspect a reasonable amount of power would be gained from a nice set of aluminum castings. Plus the aluminum would help for keeping detonation at bay. I have a 383 sbc with 12.5:1 comp and fully ported big valve 461 fuelie heads and although they won't flow as well as the newer good stuff, I like running the vintage stuff and it runs pretty hard at the track considering the heads are older than I am!
My motor isn't that different than yours, aside from the small displacement difference, the biggest difference is the comperssion. I run a solid flat tappet .570 lift older custom cam. Team G intake, modified 750DP carb, 1 7/8 headers, full 3" exhaust with mufflers. Even has an old gear drive timing for effect. Never dynoed it, but in a 3400lb 69 Firebird with 255/60/15 worn out radial t/a actual STREET tires (no traction whatsoever) having to baby it off the line(1.95 60ft.) and it had no problem finishing at a consistent 114-115mph, 12.2sec fighting for traction HARD for the first 1/8th.
My heads should flow a bit better, my higher compression is certainly helping me a good bit, maybe 5-10% or so. Your cam is probably a better profile than my 10 year old solid flat tappet stick. I'd ballpark guess that my motor shouldn't be more than 10-15% or so stronger than yours.
George
I just used the same perameters as before and just changed the head type to flow around 280 intake or so, and I came up with a power boost of...
hp 483 to 527 at 6500
tq 444 to 477 at 5000
As usual, this is FAR from acurate, just ballpark at best!
George
We're running people's combos in Desktop Dynos? Ooh, ooh! Run mine.
Motor Type: Small block Chevy
Cubic Inches: CID 353
Bore/Stroke: 4.02/3.48
Cylinder Head: L31 Vortec Heads
Valves: 1.94/1.5
Exhaust: 2.5-2.25" H-pipe
Headers: Yes, 1 5/8ths primaries and 2.5" collectors.
Mufflers: Yes, Turbo style, 2.25" in and out
Cam: Hydraulic Flat, .447"/.454" int/exh 212/218@.050 110LSA 106 Centerline Comp XE256H
Intake: Edelbrock Performer Vortec
Carb Type: Qjet, 750CFM
Compression Ratio: 9.25:1
304 HP @ 4k, 384 Ft/LBS @3.5k Desktop dyno 2000 figuresQuote:
Originally Posted by 76GMC1500
Cool, thanks. The time sheets seem to confirm those numbers.
I get 339 hp at 5,000 rpm, 443 lb-ft torque at 2,500 rpm .............
Kitz
First of all you don't have enough compression to run that cam.Quote:
Originally Posted by Hopper111
Second your heads are to small.
Again if you want to run the 377 you will have to gear the $hit out of it to get it to work and run a really loose stall.
Ask any one who runs a dirt mod. and they will tell you a 377 is great for a "dry slick" track because it will take a lot of the low end torque away.
Then ask them for a "tacky" track what they would run and they will say a 383/406.
cool, thanks guys. i was counting that with my choked up cast iron heads i'd make somewhere between 450-500 hp. This has been a ride. For $2500 I've managed to put together a complete engine and valve train minus the head castings to put the valve train into that is capable of 500+ HP and a healthy shot of nitrous. Not bad in my book. Granted, to make this puppy into a fire breather monster, you'd need to put some money into a good pair of cylinder head castings. However, I have everything needed to assemble the cylinder heads/valvetrain. Not bad. Just wish i was still into the racing scene and still needed this motor :CRY:
I gave the specs to those particular cylinder heads because they are the only pair that I have. The thought crossed my mind to use them, but i knew that they wouldn't breathe well enough for that cam and the chambers would be too big to really let that cam rip. I just thought that if the motor made decent numbers with those old heads, it would make great numbers with a good pair of heads.
Also thinking of selling this motor to pay for my books and tuition for my college classes. What would be a fair price for this motor? (I have everything except carburetor, distributor, and cylinder heads. The valve train and shortblock are complete)
As much as I like to hear it, 443 ftlbs at 2500 rpm seems a little optimistic. The motor doesn't really come alive until 3000 rpm so I would think the peak torque is above that.
hi George... I think the big difference between our numbers came from the cam duration. Hopper said he's using a 242/242@.050 and you used 296/302 (seat-to-seat?). For heads, I used flow numbers for 441 and added 10cfm fudge to account for the larger valves. I think the Torker intake is limiting top end, too.
I ran again with new bore/stroke.... (BTW that comes to 379.7ci with 4.155x3.5")
With Torker ("dual-plane high torque") intake:
381hp@5000 / 479ftlb@2000-2500 (no change with bore/stroke)
With "RPM air gap-like" ("dual-plane max flow"):
446hp@5500 / 474ftlb@4500
That's a huge difference from the intake manifold.
-Chris
Quote:
Originally Posted by Hopper111
Check this out at the AFR website:
http://airflowresearch.com/eliminator.php
I think it would be interesting to see someone who has run a motor (or a few motors) on an actual dyno post their specific configuration(s), and then run the config(s) through a dyno simulator and then compare the actual vs. simulated numbers to see how close the sim actually is to the real thing.
I have a desktop dyno sim and I have wondered how accurate the thing actually is. I realize of course that if you put garbage in, that's exactly what you'll get out of it; but, I would like to see how close they actually are with the correct info.
Cheers,
Dutch
Hey Dutch,
Absolutely... no thing like the real thing but as has been mentioned before it's good to have a tool that can approximately gauge the benefits (or lack of) for certain modifications before shelling out the dough for the real thing... basically helps to make better decisions in putting together a motor. I've not had my 'bird on a dyno yet but I put in the specs of my motor (as close as I can figure) and used those specs along with other specs of the car into Desktop Drag and it's predicitions for ET and mph are within less than a 1/10th second and exactly the mph of what the car actually runs with specific weather conditions. I think it would be great to see some comparisons between Desktop Dyno (or any other sim software) and real engine dyno results. I would not be surprised if the predictions were pretty close from the results I have so far.
-Chris
Can you guys run the numbers on that motor with a this set of heads and the Air gap intake please?
They are Renegade heads with 190 cc Intake runners, 64 cc combustion chambers and 2.02/1.60 valves.
OR
They are Renegade heads with 190-210 cc intake runners, CNC ported 69 cc combustion chambers and 2.02/1.60 valves. Thanks, I'm really sorry for asking so much, but i think i'm starting to get the drive to start work on my car again instead of selling it off.
Hi, Hopper. No trouble at all... I have a lot of free time this week. Wasn't sure if the flow numbers on the Renegade heads were for the CNC ported or unported variety so I ended up using same numbers for each and only changed the combustion chamber. I was assuming 10:1 compression with 64cc chamber so with 69cc chamber SCR came down to 9.53:1
All with "max flo dual plane" intake:
190cc runner 64cc chamber: 487hp@5500/498ftlb@4500
190cc runner 69cc chamber: 479hp@5500/489ftlb@4500
210cc runner 64cc chamber: 498hp@6000/502ftlb@4500
210cc runner 69cc chamber: 486hp@6000/492ftlb@4500
Of course flow will be higher with porting but I don't have all the info so this is best I can do... in other words either the ported results are pessimistic or the unported results are optimistic...
Have fun...
-Chris
Can you help me with the HP on your dyno with this configuration
Block-dart 9.325 deck, bore 4.125 cubic inch 427
Heads- AFR 227 68cc chambers int. 2.1 ext. 1.6 full race ported
crank- bore 4.125 stroke 4
carb- 750 demon
pistons -JE dish .115 comp 11.25
cam -roller int dur. 292 ex 302 lob sep 112
rockers -jessel 1.5 total lift int .604 ex .597
headers -1 5/8 pipes 3" H pipe installed
intake -performer rpm duel plane
elec -fan and water pump
You will have to say what the duration is at .050 is.Quote:
Originally Posted by DADNOVA
This motor with the flat tops and a 76cc head was going to be at 10:1 so I think with a 64 or 69 cc head, the compression will be closer to 11:1. How much of a power difference does 1 point in compression make?
Hopper,
If at 10:1 with 76cc, you'll be at 10.8:1 with 69cc and 11.45:1 with 64cc. Using the same 210cc intake runner heads:
10.8:1 -> 513hp@6000/513tq@4500
11.45:1-> 526hp@6000/522tq@4500
assuming same flow rate for all heads
-Chris
DADNOVA,
Here's a cut... not sure of your rod ratio this is a stroked 400 sbc, right? I used seat-to-seat for duration and assumed 110* intake centerline. Can't account for elec pump and fan...
507hp@6000-6500 494tq@4500...
garbage in-garbage out.... this should be in the ballpark.
-Chris
what type of fuel can i get away with in this motor if i were at 11.45:1?
I got a little carried away, i wanted a *street* motor and ended up building way too much engine. If i could go back i would, but unless someone buys this motor, i'm stuck with it. I shoulda built a big block:D
I.M.O,I would either go all the way to 13 to 1 or go back to 10.5 to 1 for a comp ratio.Quote:
Originally Posted by Hopper111
At almost 11.5 to 1 you will have to mix race gas with pump gas.
Yes it is a pain in the a$$.
[Can you help me with the HP on your dyno with this configuration
Block-dart 9.325 deck, bore 4.125 cubic inch 427
Heads- AFR 227 68cc chambers int. 2.1 ext. 1.6 full race ported
lift flow int ex
.2 138 112
.3 207 150
.4 258 190
.5 294 207
.55 298 213
.6 302 220
.65 305 225
.7 309 230
crank- bore 4.125 stroke 4
carb- 750 demon
pistons -JE dish .115 comp 11.25
cam -roller int dur. 292 ex 302 lob sep 112
Int duration 292
Ex duration 302
Int lift at cam .403
Ex lift at cam .398
Total lift int.604 ex 597
rockers -jessel 1.5 total lift int .604 ex .597
headers -1 5/8 pipes 3" H pipe installed
intake -performer rpm duel plane
elec -fan and water pump[
Does that help
small block? intake center-line? rod length?
DADNOVA... with the new flow metrics, you're getting 511hp@6500 and 498tq@4500 but I'm still assuming ICL 110* and 6.544 rod length (1.636:1 rod ratio probably too long?).. I think it's safe to say you'll be making somewhere around 500/500 with that motor.
-Chris
You don't need a Jessel system.Quote:
Originally Posted by DADNOVA
All you really need is a good 7/16 roller rocker with a girdle.
Save the money for something else.
6.544 rods??????Quote:
Originally Posted by skids72
Erik... I know... sounds too long but I was working from the 1.636 rod ratio for lack of a better idea... would need a really tall deck for that(?)
-Chris
Based on a 9.20 deck height about the longest rod you can run is 6.250.Quote:
Originally Posted by skids72
In the large stroke engines 6.125 is about it.
What happens is due to the stroke and rod length the piston pin location gets up into the bottom compression ring on the large cube engines.
Are you calculating compression distance
DECK HEIGHT - 1/2 STROKE - ROD LENGTH - DECK CLEARANCE = COMP. HEIGHT ??
6 ince rods
What program are you using?
My freinds Virtural Engine Dyno shows 700 HP with 670 tourqe.
Guess I will have to take it to a Dyno shop and spend the money.
I'm just using swept volume and tweaking combustion space (chamber+gasket+dome/dish+deck height) to get the target compression of 11.25:1 ... didn't want to make a dissertation of this or anything. BTW using a more realistic rod (6.1" for 1.525:1 ratio) makes 508hp/496tq in the simulation (not much difference).
Thanks... I'm still pretty new to this and trying to learn most I can from you guys that have been there.
-Chris
DADNOVA - 700HP eh? Do you know intake lobe center line for that cam? I'm just plugging in numbers here. I'm treating your 292/302 as seat-to-seat duration. BTW I would be very surprised if you're making 1.6HP/ci in a stroker with 11.25:1 compression...
One of our 434's on meth. just cracked the 700 hp barrier.Quote:
Originally Posted by DADNOVA
That is with 14 to 1 comp ratio and fully CNC'D 23* Brodix heads and very stout roller cam.
This is why I hate some of the dyno sims they are a joke.
There is no way you will go to 700hp.
You still did'nt give the cam's duration at .050 so there is no real way to figure any of this.