A buddy of mine is having his 396 re-done, and he was giving me a rundown of what his engine builder is telling him:

1.396 +.060 for 408ci
2.going to install 10.0:1 pistons, expected compression was to be 9.5-10:1 range so pump gas can be used.
3.will use and old set of GM rectangular port heads with some cleanup
4.Cam will be a hydraulic flat tappet, approx. 520 lift, and 292 advertised duration
5.intake will be a Weiand Xcelerator
6.MSD ignition
7.stock GM crank and rods
8.balanced and 'blueprinted'

Engine shop is saying 450-500HP and 450-500ft-lb torque. I think this is a bit of a stretch..I am interested in some unbiased opinions..Anyone?

I'd say 425, 450 tops. Torque will be about 425. The rectangle port heads, and single plane intake manifold on a 396 is going to be lazy at low speeds. With the cam he's using, an Edelbrock Performer RPM, instead of the Weiand, would help the drivability without hurting peak power. I have a similar 396 that John Lingenfelter dynoed back about 15 years ago. It made 480hp with a 252 duration solid and ported Holley Strip Dominator single plane.

400 HP, 430 Torque. In order to get any benefit from rec ports on a 396 motor, you need 11.0/1CR, solid cam and the willingness to run it to 7000 RPM.

Depending on the .050 duration, the cam may not be too big. I run the Crane 286 (286/296, 226/236 @ .050) with 9.5/1 CR and oval ports. Also run a Performer 2-0 dual plane. Car has plenty of power with the 3000 Stall converter and 3.73's, but if I had a tighter converter (say 2000) and 3.31's, the car would probably be to lazy for my taste.

396 will run real good when properly done. I had a 396 .060 over 10.5:1 compression closed ovals, Isky 292/590 hyd mega cam, Weiand hi rise single plane intake/850dp, hooker super comps, points dist, Th400/3,500 stall, 4.56 12 bolt. I shifted the car at 6,500rpm and it would run 11.70's all day. Just my opinion

that cam has alot of advertised duration for no more lift than that. seems that most cam manufacturers that have advertised durations of around 292 usually have the lift at around .550-.575. i would be surprised if that motor makes within 50 hp or 50ft/lbs of torque of what that shop is claiming. if it does make that much power alot of us will need to rethink our own combos. an rpm air gap and ported 049 or 781 oval ports would be ideal for that motor, IMO. along with some 1 3/4" headers, i think it would make a fine running little big block, although i still doubt that it would be even approaching 500hp. if it were a 454 with those parts i'd say yes, easily capable of 450hp, just doubt a 396 can accomplish that with 10 to 1 compression and heads that are too big and an intake that is not ideal for the motor. are they going to dyno the engine? it'd be interesting to see their results if they do.

I had prity much the same cam in my 496 with edelbrock oval head worked on good and a performer rpm intake and I would of put it at 450hp but it made a ton of torque. That was do to the small cam and big cubes. I would say that your friands motor will be around 400 to 450hp on the cunservite side.

Install an Isky 280 Mega Hy-cam on 110 centers in it instead of that cam, imho....

292 is too much advertised duration at that CR., imho...

And, yes use a good dual plane intake and 1.75" dia., four tube, long headers. The headers are free hp...

pdq67

Single plane intake and square port heads on a 396..no good,unless the car weighs less than 3200 lbs. and has 4.56's

450-500 hp and 450-500 ft/lbs tq..thats quite a range..a dirrerence of 50 HP is tremendous

a pair of oval port heads and a dual plane intake will be best,along with no more than 240 duration @ .050 (235 is best IMHO)

FOr an extra $200.00 why wouldn't he drop a 454 crank in there and easily get that HP and TQ he wants???????

396 .090 over
10.5 to 1 compression
233/239 @ .050 with .548/.551 lift hyd. cam
oval port heads '390 cast ..ported by me..2.19/1.88 valves
rpm intake
3310-2 holley ...lots of mods done to this carb
summit headers
full exhaust 2 1/2" to the mufflers 2 1/4" tail pipes.

thru many test and tune sessions... it has pulled over 107 mph in the 1/4 in a 3900 lbs z28 in street trim. and it likes 6500 rpms for best mph times.

i dont think to many would argue that it makes right around 370 hp at the rear wheels which it should pull an easy 450 hp on the flexplate.

i really think that 396 with rect. heads and single plane intake is REALLY going to be lazy down low specially under the 3000 mark. and thats not really a good match for that cam.....that cam is similar to the crane fireball 2 cam that is 290 advertise duration with .515 lift and 216@ .050. it just wont make any real hp because the cam will be done at or near 5200 rpms just when the heads and intake are wanting to shine.

not only will it be lazy it will lack a lot hp. i see more like around 350 gross hp comming from that combo.

to make the 450 or 500 mark it will need the compression higher, bigger cam and the willingness to run it up around the 7200 rpm mark.

i just dont think its a good combo and i wouldnt even build one like that. the 10 to 1 compression range is ok and the cam would be ok but need to go with oval ports and dual plane intake and vacuum secondary carb. this may make about the same hp or more as the current (my guess on hp of 350) sketched up plan but it will have the torque and the pull all the way thru the rpm range like it should.

Here is my suggestion. Sell the rectangle ports to somebody who really needs em. Like the others have said, they will be real sloppy at low rpm and wont provide much more horsepower than an oval port only because the rest of the combo isnt tailored to work with a rectangle port head. Get a set of 290 or 702 oval port, closed chamber big block heads. Stick with the stock valve sizes cause they are more than large enough for about 450 horses as long as the combo is right and the cylinder head port work is accurate.
Smooth the short side raidus up nicely so it rolls around with no cliffs or hard edges, fit them with new, stock size backcut valves and a good valve job, smooth the hard edges on the valve guides but dont shorten them, open up the valve throats to about 75% of the size of the respective valve, gasket match everything and polish the exhaust ports nicely. Than go with a performer rpm intake, and the mention of the isky 280 mega cam is a good one. Compression should be somewhere between 10-10.5:1.
Thats another issue with the current camshaft and compression. Judging by the high advertised duration, but low valve lift, it sounds like its probably an older grind with lazy lobes and I bet it has a large intake valve closing angle, and with only 10:1 compression, that will make dynamic compression end up being lower than what you would want in a performance motor. I could be wrong on that one cause I dont know all the cam specs, but thats my guess. Either way, this will provide an honest 450 horsepower/450 torque(maybe more, maybe less, depends a lot on the quality of the headwork and the tuneup), and it should pull enough for 6500rpm but not be super sloppy at more streetable rpm levels. Definitely a motor that would put the average motor into the high 11's or faster with a 4.1 gear and about a 3500 converter in a 3400lb car. It would work with 3.73 gears and a 2800-3200 converter, but It would most likely be stuck in the 12's but once again, if the heads are really taken care of, it still might be able to touch those 11's even with the slightly milder gear and converter. As the combo stands now, it can probably go just about as fast as the setup I just mentioned, but the only time it would ever feel like it had any serious power is under full throttle operation. Other than that, It will be sloppy. No part throttle manners, and it would definitely need the bigger gears and converter too, if not a little bigger than that.

I dynoed a .060 402 last month that i had built for a friend made 470hp at best, combo is.
10to1 cr
990 bowl ported ret port open chamber GM heads
Engle roller 252°/263°@.050 112°LSep.625lift
Edelbrock Single plane manifold/750 holley

The car has run 11teens @118 3750# chevelle
He was a little shocked at the hp numbers,

He and everyone else figured it woulda made 550 or so.
Magazine hp and real life hp is a different ball game.

Originally posted by 1968 hot rod:
I dynoed a .060 402 last month that i had built for a friend made 470hp at best, combo is.
10to1 cr
990 bowl ported ret port open chamber GM heads
Engle roller 252°/263°@.050 112°LSep.625lift
Edelbrock Single plane manifold/750 holley

The car has run 11teens @118 3750# chevelle
He was a little shocked at the hp numbers,

What gear? What convertor? (if auto)
I know some unique combos can be put together that you don't think would run well,and maybe that motor is an example,as the car weight,the trap speed and HP numbers don't add up for that combo..thats a pretty big cam too and I'm sure it needed a lot of gear to run 11 teens.
I also agree with the statement "Magazine hp and real life hp is a different ball game"

Let me add some further info, and when I can figure out what all the cam specs are, I will post them..

Carb: 750 Holley DP, howevery shop is telling him to sell it and get an 850.

Rear: GM 12 bolt, 4.11 gear

Trans: Up in the air..TH400 is sitting there (came with the car), or conversion to 4 speed is possible (also has an M21 sitting on the shelf).

Exhaust: Hooker 2.125 or 2.25" tube headers. 3" exhaust came on the car.

Also, shop will not be dynoing..however there has been some discussion of having that done.

JTM,those headers are too big for a 396
1 3/4" primary tubes is what is needed.
One of the guys here recently swapped out his big tube Hookers to the smaller tubes and picked up ET/MPH with his 396 combo

This is going to be one very mismatched combo :eek: . You want some large oval port heads, even if they are bone stock with the small valves. Do not put a Weind single plane intake on it. Get an edelbrock air gap or rpm performer. And the 2.25 primary headers, for heaven's sake that's insane. 1 3/4 max will be plenty. That cam has way too much duration and not nearly enough lift.

His engine shop is blowing some serious smoke for sure.

JTM,

Tell your buddy if he can arrange to make the short drive over the bridge to West Chester, PA, I can let him hear run and be glad to take him and you for a drive in a bonafide 400HP 408 motor Chevelle.

I believe everyone has already told you what you need to know. But, a 396/402 can make 500hp and 550 tq. See below.....

1971 402 bored .040 over (410 CI)
1971 GM 063 Closed heads 2.19 Intake 1.72 exhaust
Flow #'s @ 600 Intake 298 exhaust 205
Static Compression Ratio 9.48:1
Combustion chamber: 100cc
6223 cross drilled crank
1.72 comp cams rockers
Comp Cams xe284H 110 lsa
matching springs retainers etc.
Eagle I-beam Forged rods
Speed Pro forged 10:1 pistons
Edelbrock RPM airgap
Holley 4160 750cfm carb.
1.75" long tube headers into 2.5" H-pipe exhaust
700-r4 transmission with 2700 stall
12 bolt rearend Auburn posi with 3.73 gears

My 410BBC has 560.42 foot lbs of torque! I am using 063 heads that have been worked on a little (2.19 Intake valves installed, gasket match, 5 angle valve job, little porting)Edelbrock Performer Air-Gap, CC xe284H cam. Oh Yea, it made 498.6 Hp.

Regards,

Steve,

How did you verify those numbers - engine dyno, chassis dyno or sim program?

Originally posted by GRN69CHV:
Steve,

How did you verify those numbers - engine dyno, chassis dyno or sim program? =
LOL you took the words right out of my mouth ;)

Steve, are those Desktop Dyno numbers?
I just got done dynoing a 450HP crate 502 that didn't make those numbers?? :D

Originally posted by Wolfplace:

Steve, are those Desktop Dyno numbers?
I just got done dynoing a 450HP crate 502 that didn't make those numbers?? :D [/QB]Yep, I think desktop dyno just struck again. graemlins/clonk.gif :D

Mr 4speed,
The car has had both 4:11's and 4:56's in it only about a tenth difference.
I'm sure it would run better with ported oval ports,but its not my car.
He runs an 8"ATI converter,750 holley dp,power is all in bye 6500/6600 on motor w/mufflers.
We will be at Atco on 11/20 running the 10.0 index race if its not snowing.

Hey Mike,
Have you ever dynoed with a Stuska dyno?
If so what is an approximate % differance between the two hp wise if possible.
Thanks

I don't care about chassis, engine room or desktop dyno - that is one gorgeous red Chevelle, Steve! That sucker looks fast while it's setting still.

Originally posted by mr 4 speed:
JTM,those headers are too big for a 396
1 3/4" primary tubes is what is needed.
One of the guys here recently swapped out his big tube Hookers to the smaller tubes and picked up ET/MPH with his 396 combo that would be me graemlins/waving.gif
car felt more powerful at all rpm

Hi Guys,
I'm not too sure of Steve's combo making that power. 498HP/560tq. Did Steve post his best ET/mph?
That would indicate the real power of the combo.
I run a 396 combo with large oval "truck" castings # 136. The usual stuff,performerRPM,750dp
I run a mild custom street roller from Comp.
my baby rat is making around 470 or so.

Steve-Ditto the comment on your car, it is beautiful, I really like the wheels!! As for the HP #'s, that must be one hell of a set of flowed heads on there!!

I have a similar setup 396 and its right at 425hp and 440 ft-lb of torque (measured on Superflow 902 Dyno). Did I miss on the cam selection???

Tell us more!!

Heck, again!! an Isky 110 center, 280 Mega cam, a good rect port. dual plane and a set of 1.75" four tube, long headers and it will run fine UNLESS you want to get into your motor and change to oval port heads like the guy's are talking about.

Should be an all right street motor anyway, imho....

pdq67

Originally posted by pdq67:
Heck, again!! an Isky 110 center, 280 Mega cam, a good rect port. dual plane and a set of 1.75" four tube, long headers and it will run fine UNLESS you want to get into your motor and change to oval port heads like the guy's are talking about.

Should be an all right street motor anyway, imho....

pdq67 Pdq, I think the Isky Mega 280 comes with a 108 lobe separation.

396 .040 over/404
10.8/1 Compression
Closed Chamber sq. ports 2.30 Int./1.88 Ex. with bowl work.
Brodix HV2016 HVH Intake
PRC 950 Holley
Comp Cam .604/294 256/266@.050 Solid Cam

Made 528Hp On Dyno @ machine shop

But I should have built a 540.

Dave

Now I can see the above motor making some serious power. 10.8/1 (call it 11/1), and a big solid cam. Bet max HP came in around 6800+ though. You would have to spin a 396 rec port motor fairly high to get that kind of power.

I believe Steve's car went mid-high 13's at around 103 or so on street tires.

Check again b/c Isky makes two of them, the 108 and a 110!

I think they recommend the 110 for more like boats but it's been a while..

Anyway, the 280 Mega on 110 should do nicely, imho..

pdq67

Chris,
Thanks for posting steve's times/mph. I thought that was about what he had run. I remember a video post of his runs.
Steve's combo is VERY similar to mine.
same trans, converter, gear etc.
The dyno numbers do not match the actual performance.... something is amiss.
As to the original post question, I would not put rect. port heads on a 396 for street duty.
oval ports on a small BBC work best below 6K

Dave,good to see you posting again graemlins/thumbsup.gif

Thanks Chris.....been real busy.
Did you get any more runs with the new 3.31's?

Dave,only runs I got in were some 13.07-13.09's..need to do a little tuning and improve the 60 ft. to take advantage of the gear swap.Real fun on the street though smile.gif

Guys, the numbers are from the original dyno pull made at Lamar Walden Racing Engines. I will try to scan the graph and post it here. I posted it once but cannot find it now. Several members of this board are familiar with Lamar and his work. I also believe that if you speak to any members of this board that know me, they will tell you that I have never claimed to have a fast car. After all the old girl weighs more than 4200lbs with me in it. All I was attempting to do was answer the original question... "396 HP potential?". I have never done any tuning to the combo at all. I still run the Street Avenger carb exactly how it came out of the box. Below I will paste the post I sent when I took the car to the track for the first and only time (excluding the 3 passes at Chevellabration this year). I will leave the fast cars and great track times to people like Ken Jett, Bill Burke, Mike Newby, and Gordon all of which know much more about these cars than I do. I will just put around in my car and enjoy it on nice weather days.

Well Guy's today was the first time I went down the 1320. I was proud of the "Old Red Girl" but the driver ain't too sporty..

1st run
R/T ... .896
60' ... 2.253
330 ... 6.051
1/8 ... 9.086
MPH ... 81.61
1000... 11.682
1/4 ... 13.856
MPH ... 103.87

2nd run
R/T ... .871
60' ... 2.238
330 ... 5.473
1/8 ... 9.089
MPH ... 81.29
1000... 11.692
1/4 ... 13.873
MPH ... 103.45

I always thought that driving the 1/4 mile was simple. Light turns green, floor it, the motor does all the work, strong motor, great time. WRONG!!!!!!!!!!!
The car pulled hard. The driver couldn't figure out how to not spin the tires all the way through 1st and 2nd. I believe the driver saw the green flag drop, pulled up his skirt, and wet the bed! As many times as I told myself "leave at 1500, roll into the throttle SLOWLY, do not break the tires loose, shift into 2nd at 5500 and then into 3rd at 5500, roll through the traps, and smile at the 11.00 time slip".
NOT!!!!!!!! Anyway,

Thanks alot to Ken Jett and this wife, Bill Burke and his wife, and Gordon. Although, I followed none of you advice, I appreciate you offering it.

On a good note, I will tell you all that I am now HOOKED!!

Regards,

--------------------
Steve Haraway
1971 Chevelle SS

Steve,mid-high 13's with a 396 on street tires is impressive in my book graemlins/thumbsup.gif
I bet our motors make about the same HP going by our trap speeds

Steve, Talk about duplicated results - early August - nice and hot/humid though. I went 14.20 @ 99.7 and 14.07 @ 97.xx. 60' times were almost identical.

408 motor 9.5/1Cr
290 CC heads 2.19/1.72
Performer 2-0 (little bit of port match)
Crane 286 (226/236, .535/.551 on 112LSA)
T400 w/ 3000 stall
3.73's
275-60/15 street tires

Spinning and sloppy out of the hole.

I would think in your case, the lower first gear of the 700R made up for the much larger cam, but you picked up 3mph on the top end. Just goes to show what can be expected from a true street combo. From the info I have been able to find, my in the car HP was around 330 - 340HP based on the weight and MPH. To get the extra 3-4 mph, you were probably a good 40 - 50 HP over what I was actually producing back in August.

Originally posted by 1968 hot rod:
Hey Mike,
Have you ever dynoed with a Stuska dyno?
If so what is an approximate % differance between the two hp wise if possible.
Thanks Nope but I have a friend with a Stuska with DePac & the corrected numbers are very close to mine & both always seem to be about 10-15% down from the super duper wiz bang magazine numbers given about the same combinations.

I do a 332" SB that dynoed like 730-740HP,in Los Angeles at a well known facility & mysteriously lost about 50HP on the Stuska & 60+ on mine.
It is 667HP on my dyno & it was like 10-15HP more on the Stuska.
He has since gone to a SuperFlow & says his numbers are "very close".
Amazing thing is, this little mouse outruns a couple of 700+ deals down the straights at more than one track,,, same gear, weight, basic car type,,, :rolleyes:

Dyno numbers are just numbers & can be manulipulated very easily to anything you want.
The true test is what is the weight & what MPH did the car run. This will tell you within reason what the HP is under those particular conditions on a given run.
If you take the simple little formula I have posted numerous times you will be reasonably close.

Here is the little formula that has been around since at least the 70's & was used by Chrysler Corp. in their drag racing program & written up in the American Journal of Physics in 1973
HP=(.00426*MPH)cubed * WGT
I add about 50 HP to the number because trap speed is measured differently now than it was in the 70's & I believe Harold Sutton has posted that he uses a factor of 1.072 as a multiplier & comes closer.
This is flywheel hp not RWHP ;)

So, 104 @ 4200lbs is approx 400-420HP under whatever the conditions were on that particular run which is a very stout mild 396 & you have to remember this engine on the dyno is probably going to be higher because the dyno numbers are corrected for "perfect conditions" so Steves engine could very well be approaching 500HP on the dyno again depending on correction differences but I would question the torque number ;)

BTW Steve, went & looked at your pics,,,, VERY NICE graemlins/beers.gif

Mike,

104 MPH Wt= 4200#, I come up with 361HP x 1.072 correction factor = 387HP. I would be willing to bet that is close to the real number.

In my own case:
99.9 MPH Wt= 4200# (complete 69 Coupe w/ 250# driver - has to be real close to this). I come up with 319HP x 1.072 = 342HP. I would be this is also real close to the "real world installed HP".

If I remember right, in the old days, the installed HP loss was about 70HP less than the advertised gross HP ratings - at least when they changed over from Gross to SAE net in '72.

Using your formula, 500HP would pull a top end of: 115 - 116. Which is probably fairly accurate.

Joe,wouldn't you take the 342 HP and divide by 80% to get the HP at the crank,which in your case would be 427.5?

Chris,

Ironically, I have one of the old school Speed-Power Slide calculators at home. When I finally made the runs in August, I ran the numbers on the slide calc. and got basically the same number. But yes, dividing by .80 would get a crank number as opposed to a chassis number - I'm still unclear as to which number the Chrysler Formula or the speed/power calculator is supposed to give. But I would also assume, you would want to apply the .80 chassis/crank correction estimate to the baseline number - which in my case would be 319HP, then divide by .80 = 398.75. All in all, that is still not bad considering my 408 motor is basically a '70 spec 402/350 motor with 6 more cubes, 12 degrees more cam duration and a 2.19" intake valve over stock.

Give or take a couple HP, I managed to achieve 1HP/CI out of a basically stock 402 motor which if you break it down, it all falls into perspective. 408CI/400HP, 427CI/425HP, 454CI/450HP, 502CI/502HP. These are all real world numbers. And I would add that IMHO and experience, a higher output engine has the greater potential of losing a greater percentage of power strictly due to tune and operating conditions, whereas, a mild larger displacement engine will produce the bigger HP under more adverse conditions with less potential for an extreme power loss.

In the case of the first thread - taking into account what you want to achieve and assuming you want the motor to be driveable and reliable (I know these are vague wide open parameters), I consider 1HP/CI to about 1.1HP/CI to be what many consider as practical and reliable.

Hi Wolfy, The MPH conversion is 1.0072 instead of 1.072, you left out a zero. This makes todays MPH readings the same as the full 1320 ft. of yesterday according to Meaux Racing Heads. Meaux also has software to completely analyze your run and give a detailed breakdown of your run along with horsepower numbers that they claim are accurate down to + or - 5 H.P. if you give them a run with detailed info to work from such as the 60' E.T., 330' E.T., 660' E. T. & MPH as well as quarter mile numbers. This is really good stuff if it works, which i haven't tried yet but plan to soon.

Originally posted by mr 4 speed:
Joe,wouldn't you take the 342 HP and divide by 80% to get the HP at the crank,which in your case would be 427.5? Chris,
No, the Number is flywheel HP not RWHP
I realize there are a few places claiming this is RWHP but it is not.
It is pretty simple to do some calcs most everyone knows to get some reality here.

A good one would be Pro Stock
Use the formula for 2350 lbs & say 204 MPH.

Now the numbers will be high in this type of power range as the formula is the most accurate around 100 MPH, but even given that a pro car has a super efficient drivetrain,,, lets call it 10% for giggles you are now at 1700 flywheel HP
if you use the formula for RWHP :rolleyes:
I highly doubt you are going to see 1500 engine HP let alone 1700 in a pro engine ;)

====================

Hi Harold, hoped you would see this as I didn't remember the number but that makes the factor even less, :(

Well Guy's I can now post the one of the Dyno runs. I cannot find the graph of the run that had the max torque of 560 but this one should give the gallery enough info to pick to death.

http://www.chevelles.com/showroom/USFATL/Dyno1.jpg
http://www.chevelles.com/showroom/USFATL/Dyno2.jpg

If anyone wants or cares to see, I can post my Blueprint seet as well as my flow numbers.

Regards,

MORE INFO...

Ok, relating back to the original question at hand..the came my buddy was told would be installed is a Comp cam, #: CL11-213-3. Also, compression ratio is to be 10.5:1.

Roller tip rockers will be used also.

I think thats about all I can pull out of him..any changes of previous opinions??

HERE are the cam specs:

11-213-3
Engine 1965-1996 Chevrolet
396ci-454ci
8cyl.
Grind Number CB 292H-10
Description

--------------------------------------------------------------------------------

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.55 0.55
Duration At 0.006 Tappet Lift 292 292

--------------------------------------------------------------------------------

Valve Timing At 0.006
Open Close
Intake 40 72
Exhaust 80 32

--------------------------------------------------------------------------------

These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 244 244
Lobe Lift 0.3235 0.3235
Lobe Separation 110

--------------------------------------------------------------------------------

Recommended Valve Springs 924-16

Ok the cam specs help. Getting back to my earlier point about your compression, you say it should be between 9.5-10:1. Assume it ends up being right at 10:1, and with that cam and a 72 degree intake valve closing angle, that puts your dynamic compression ration at roughly 7.5:1 compression. Well within the limitations of pump fuel. It would be better with about 7.8:1dcr, and as much as 8.2 dcr can be done with an iron head, but keep after the tuneup. To be safe, I would shoot for 10.5:1 static compression ratio. This puts your DCR and roughly 7.9:1 and that will wake the motor up a bit, but also work with premuim fuel under most conditions without worry. DCR is not the end all be all though. Its a real good reference, but not perfect cause there are other determining factors. At higher rpm, a really efficient combo will get so much air moving at such a high velocity that it really packs in more pressure than what would be expected with a given DCR. Think of it this way, two motors have the same DCR, yet one has much better heads that flow plenty at a given rpm and the other motor has peanut ports that are really restricting the motor at the same rpm. The motor with the restrictive top end will not squeeze as much air into the chamber on the upstroke that the engine with the better top end is capable of even with the same DCR. In your case with the hydro cam and older heads and basically average top end, the DCR numbers will be a good reference for you. If they were some real high flowing aftermarket heads and a faster acting roller camshaft, you would want to be careful, but once again, as much as 10.5:1 will be safe with that camshaft. Hope that wasnt too long or confusing.

Thanks Greg..that was one of my next questions..as to whether the compression ratio was going to be too high for pump gas.

Originally posted by USFATL:
Guys, the numbers are from the original dyno pull made at Lamar Walden Racing Engines. I will try to scan the graph and post it here. I posted it once but cannot find it now. Several members of this board are familiar with Lamar and his work. I also believe that if you speak to any members of this board that know me, they will tell you that I have never claimed to have a fast car. After all the old girl weighs more than 4200lbs with me in it. All I was attempting to do was answer the original question... "396 HP potential?". I have never done any tuning to the combo at all. I still run the Street Avenger carb exactly how it came out of the box. Below I will paste the post I sent when I took the car to the track for the first and only time (excluding the 3 passes at Chevellabration this year). I will leave the fast cars and great track times to people like Ken Jett, Bill Burke, Mike Newby, and Gordon all of which know much more about these cars than I do. I will just put around in my car and enjoy it on nice weather days.

Well Guy's today was the first time I went down the 1320. I was proud of the "Old Red Girl" but the driver ain't too sporty..

1st run
R/T ... .896
60' ... 2.253
330 ... 6.051
1/8 ... 9.086
MPH ... 81.61
1000... 11.682
1/4 ... 13.856
MPH ... 103.87

2nd run
R/T ... .871
60' ... 2.238
330 ... 5.473
1/8 ... 9.089
MPH ... 81.29
1000... 11.692
1/4 ... 13.873
MPH ... 103.45

I always thought that driving the 1/4 mile was simple. Light turns green, floor it, the motor does all the work, strong motor, great time. WRONG!!!!!!!!!!!
The car pulled hard. The driver couldn't figure out how to not spin the tires all the way through 1st and 2nd. I believe the driver saw the green flag drop, pulled up his skirt, and wet the bed! As many times as I told myself "leave at 1500, roll into the throttle SLOWLY, do not break the tires loose, shift into 2nd at 5500 and then into 3rd at 5500, roll through the traps, and smile at the 11.00 time slip".
NOT!!!!!!!! Anyway,

Thanks alot to Ken Jett and this wife, Bill Burke and his wife, and Gordon. Although, I followed none of you advice, I appreciate you offering it.

On a good note, I will tell you all that I am now HOOKED!!

Regards,

--------------------
Steve Haraway
1971 Chevelle SS there's ALOT of power being lost somewhere then. your track times are almost identical to my 93 LT1 Z28 that is bone stock, rated at 275hp. i only ran it 1/8mi but it went 2.17 60ft, 9.05@81mph. i know the Z28 is probably 5-600lbs lighter, but that can't explain a 200hp difference. :confused:

JTM,

That cam is the 292 Magnum. Forget the advertised seat for now, 244 @ .050 in a hydraulic with rec ports and 9.5/1 will be a stone below 3000. That cam needs 10.5 - 11.0 CR and 4 series gears. I probably would not even consider that cam for a 10.0/1 454 motor unless it had big gears.

Not to muddy the picture here regarding what HP
Steve's motor is producing. (beautiful ride by the way).
My '71 Chevelle is very similar in setup.
same engine, trans and rear gear.
using the calc. Mike provides
114mph with 3880lbs =444HP
corrected to 1.0072=447HP

using corrected RWHP with 20% loss = 482HP
my guess is i'm making somewhere between these numbers.
My point is with 498/560 power Steve's car should run more than 103mph.
Could he have lost that much power? stock manifolds,restrictive exhaust......
JTM are you interested in the cam I'm running?

I hate to say it but if you load the engine into a Mr Gasket or other horsepower programs you'll be within 10-15hp of what it will do. I'm not a huge fan of these programs but the information will be a lot closer than what you engine builder is telling you. The program does well with the Chevrolet stuff. Just remember, garbage in and garbage out.

Jim

PS.........Don't tell your engine builder you are using the program as they freak.!!!!!!!

Dave: Yes, what cam are you running and what are the specs? Id like to compare to my set (Lunati 02005 LSK) and the comp 292 magnum...

JTM6o,
The cam I run is a custom solid roller from Comp Cams.
P/N 11-000-8
grind #cb4873B/4875B R 113.0
duration at .015 = 273 intake 285 exhaust
at .050 = 236 248
lift .640 .654
lobe seperation =113
installed at 108 ICL.

With the wider LSA this cam provides a relatively smooth idle.
I shift the car at 5900
the Dynojet showed peak power at 6000.
This setup works well with the wide gear spread and RPM drop the 700r4 has on the 1-2 shift.
With the overdrive tranny in lockup at low RPM it pulls smoothly.
The +12 duration at .050 on the exhaust with a wide lSA works well with my large oval truck heads.
This may not be the setup to use with rect. port heads on a 396.
Just sharing what has worked for me.