Teal91rs

Hey,
Well i was playing around with desktop dyno tonight and i was basicly shoping around for cams that i might get this christmas. When surfing though the GM inventory i found the l69 cam and just pluged it in to see the results i advanced the timing +8* and made shure they where the at .050 mesurements and ran the combo and got some shocking results! I wish i could screen captrue but i will just write the results out for you and ask can this be right?
Rpm Hp Tq
2000 145 380
2500 181 381
3000 221 386
3500 257 386
4000 282 371
4500 295 344
5000 289 303
5500 261 249
6000 223 195
6500 174 141
7000 120 90
7500 66 46
Its a 350 bored .30 over with 822 castings and 2.02,1.60 valves 650 carb at 1.50 inHG with a dualplane mainfold mall tube headers and mufflers with the l69 cam at +8*

Teal91rs

Ive found thta when i lower the time to 5* advanced it yeilds even better gains!
Rpm Hp Tq
2000 145 380
2500 182 381
3000 221 386
3500 259 389
4000 288 387
4500 304 355
5000 302 317
5500 281 268
6000 245 200
6500 150 113
7000 99 69
7500 40 27
THis has to be wrong

nsimmons

Remember dd calculates gross flywheel power. Knock off 15-20%

Thats completley reasonable the stock 305 is rated at 200net your showing 280 gross with a better exhaust and larger engines..

For what its worth my engine shows 323 grosshp in dd with completley stock 882's

[edit]

i just switched my cam to the l69 and the torque peak dropped 1500 rpms, but i yeild similar results, nothing suprising.

ME Leigh

DD is highly inaccurate for power results, it is only good for comparative results.

Any dyno results you do on DD are almost worthless, they only calulate the absolute theoretical maximum power output.

eric17422001

I agree DD is innacurate.

I have a .030" over 350 with stone stock 882 heads, 1.94 intakes, 1.60 exhausts- about 8.5:1 CR.

With a Comp 268XE cam, Weiand Action Plus dual plane, small tube shorty headers and Q-jet. Desktop predicted 322 hp and 363 ft/lbs torque.

RWHP was 201 @ 5200 with 248 ft. lbs of torque at 3400.

Add 20% for drivetrain loss and I'm actually making about 240 at the crank.

Given the flow of the heads, I'd have been better off with a milder cam.

RB83L69

To put those heads in perspective:

I have a 305 (that's the 0 before the 5) with flat-tops and 186 heads. Yeah I know, but I just have kind of alot of 186s laying around. The cam I used is a Comp XR264HR-12; SLP 1¾" headers; ZZ4 intake; completely totally absolutely bone stock 83 L69 carb & distributor & air cleaner, all emissions devices installed and operating (except for the EFE, which the SLP headers don't support), the stock exhaust including the cat.

It measured 237 RWHP and 266 RW ft-lbs.

This was at a local Mustang club's Dyno Day event, near the end of the lineup of cars. Embarrassed quite a few of those guys that had shot their mouths off about how their cars were so fast and all, and why they thought these (carbed motors in general, and early third gens in particular) are so obsolete and how Chevys don't run and so forth. They were mostly doing 205-210 RWHP that day, or up to 220 or so for the stick cars. A few didn't crack 200.

Power lives in the heads. If you do the right thing there, you'll have a chance at getting some out of it. 882s are NOT the right thing, as clearly shown by the numbers. No matter what DD2000 says. Having built motors all through the late 70s and early 80s for people who had yerbasic smogger 350, and heads at that time being far less common and cheap than they are now (before the invention of CNC casting), I can tell you over and over and over again about disappointing results from 882 or 624 heads and domed pistons and any kind of cam there was back then. That included stock ones (929), the various old GM cams especially the "151", the various 230°/.465" ones, the Melling cams such as the MTC-1 (same as Edelbrock Performer and Summit 2102), and even up to the Comp HE series. None of them overcame the flow deficiency that the heads created.

As was said, the absolute numbers that DD and similar programs give, are not to be trusted. What those programs are good at, is evaluating changes. i.e. change the cam, see if the power goes up or down, or see what RPM band it moves to. That's actually the one thing they do the best, is allow you to tune the cam to the need of th erest of the combo. If you don't have actual measured flow #s for your heads, or they don't exactly match the configuration of the supplied files, they're prety hard to substitute for. The program CONSISTENTLY OVERESTIMATES the power that will be produced by smogger heads, sometimes grossly; and is much more accurate, sometimes even pessimistic, with actual performance aftermarket ones.

F-BIRD'88

If you lie to desk top dyno ( input the wrong values) it will lie right back at ya.

a head like a 882 head is a "low performance" head.
A stock 882 will flow about 190cfm@28" and 130cfmex@28"

A "Stock head" would refer to a stock chevy camel back like a 462 or 186 in stock form. a "stock" 186 or 462 flows 210 to 214 cfm. Big difference.

typical "shorty headers" are best modeled with "High perf manifolds and mufflers" not small tube headers and mufflers.

If you Build the motor with the right model parameters you'll see that it comes out real close to what you'd expect from a 201net hp ( about 250flywheel)

I get 266hp with DD, not 322hp.

eric17422001

F-Bird, a friend of mine did the DD sim for me, and I'm sure he may have used some innacurate inputs. I was naive at the time, was using the parts I had on hand and didn't have internet access or I would have made some changes. If not a powerhouse it has been reliable for 30,000 miles of use and abuse.

I've nearly got all the parts to put the Edelbrock headed 406 together- but in the meantime the 350 is still being used.

Just for grins F-bird and since you have a lot of flow data, what would happen if I were to remove the stock 882's and bolt on a pair of dead stock 081 casting, 58cc chamber heads with 1.84 intakes? My guess is they flow equal to or a bit less than the 882's but the increased CR would make a lot of difference.

Current setup has .045" deck clearance.

Is it getting cold up in Canada yet?