Thread: 383 Low rwhp, tq

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Originally posted by erik erikson
YOUR COMBO. DOES NOT SEEM THAT FAR OFF TO ME OTHER THAN THE PORT VOLUME OF THE HEADS IS A LITTLE LARGE.I WOULD THINK IT WOULD WORK BETTER WITH SAY 190 CC HEAD OR A WELL PORTED 180 CC HEAD.WHAT COULD BE HAPPENING IS YOUR CAM IS OUT OF IT'S POWER BAND BEFORE THE HEADS ARE.

THIS,WASNT,WHAT,I,WANTED,QUOTED,OOPS!!

Cam is completely wrong for any given application. Not enough exhaust duration for N2O or forced induction. Too wide lobe separation angle for naturally aspirated. Same cam on a 106 lsa and istalled 4 degrees advanced would yield about anywhere from 40-60 more horses. Also you wouldn't have to spin it to 7g's to make HP.

One of my combos'

--383cid
--victor jr. intake
--dart 215cc heads
--holley 750hp
--comp solid roller 252/258@.050 .630/.630 1.6in/1.5ex rockers
--10:1 cr

Dyno'd lil over 500hp and 485 ft lbs all below 6200

your cam may be bleeding cylinder pressure on the exhaust side because I have 200lbs cranking pressure. I run pump gas with a 0 deck and .039 head gasket. I run 36 degrees timing and 76/84 jets in the carb. 3" exhaust, 40-series flowmasters.

Thanks, Ray...BTW what is the part number on your Comp cam?

yea make sure ur carb is tuned right , that can make a big difference

Originally posted by camaro_fever68
THIS,WASNT,WHAT,I,WANTED,QUOTED,OOPS!!

Cam is completely wrong for any given application. Not enough exhaust duration for N2O or forced induction. Too wide lobe separation angle for naturally aspirated. Same cam on a 106 lsa and istalled 4 degrees advanced would yield about anywhere from 40-60 more horses. Also you wouldn't have to spin it to 7g's to make HP.

One of my combos'

--383cid
--victor jr. intake
--dart 215cc heads
--holley 750hp
--comp solid roller 252/258@.050 .630/.630 1.6in/1.5ex rockers
--10:1 cr

Dyno'd lil over 500hp and 485 ft lbs all below 6200

your cam may be bleeding cylinder pressure on the exhaust side because I have 200lbs cranking pressure. I run pump gas with a 0 deck and .039 head gasket. I run 36 degrees timing and 76/84 jets in the carb. 3" exhaust, 40-series flowmasters.

THE WIDE LOBE SEPERATION GIVES YOU A LITTLE WIDER POWER BAND.YOU ALSO STATE BY HAVING THE CAM GROUND ON 106 L/S AND IN STALLING IT AT 4 DEGREES IT WILL GIVE IT 40-60 MORE H.P.I REALLY WISH IT WHERE THAT SIMPLE.

Man, that camshaft is way too big for a 10.5:1 compression motor, with the 215cc runners it is having a hard time breathing in that much volume. With your relatively low compression you should be runing a camshaft with around 236@.050"....also a runner volume of around 180-190.....this is why you have low numbers, your compression can't support that camshaft. This is obviously a race motor, so you are eother going to have to run a way higher compression or stab in a smaller cam and head package. You can't mismatch the head and camshaft.....this is what will happen.....Jmo

Originally posted by erik erikson
THE WIDE LOBE SEPERATION GIVES YOU A LITTLE WIDER POWER BAND.YOU ALSO STATE BY HAVING THE CAM GROUND ON 106 L/S AND IN STALLING IT AT 4 DEGREES IT WILL GIVE IT 40-60 MORE H.P.I REALLY WISH IT WHERE THAT SIMPLE.

Erik, you are right hands down on that the power band is wider on a wide LSA. The problem is that comes at the expense of torque and horse power throughout the wider rpm range. IN short the engine needs the 106 LSA for better scavenging intake vacuum during overlap. Proper cam design is as important as proper head design and those 215 runners are not to big for a 383. The cam is the place to start, and it is that simple. Advancing the cam 4 degrees is going to trap more cylinder pressure for one and make more bottom end power to keep the engine from having to spin to 7g's to make it's power,,,for,two.

My Comp part no. is 12-900-9, I run a 850 Proform DP, my cam is installed on a 102 intake centerline, I have 200psi cranking pressure. I run 32x18.5 Mickey Sportman PRO's 4.11 gear TH-350, 2500 stall. It equals out to a 1.55 60ft. 11.20's ET@122mph crossing the line @61-6200RPM all on motor and pump gas. The only thing wrong with this combo is stall but if I went up on it I wouldn't hook on the street.
The RPM range listed on my cam is 3200-6200.

P.S. I know engine vacuum is dead low during overlap. When I refer to intake vacuum I am refering to the rushing exhaust gasses drawing intake charge into the cylinder. That is why tuning collector length can play a big part in engine tuning. Had to say that so my buddy wouldn't get

Originally posted by big_G1
When I was looking at head flow numbers, the Vic.'s did not flow as well as AFR 190's or 195's. Now I have to decide how to pick up the torque. Smaller runners? Or will a cam with less duration and overlap raise the torque enough to bring the hp. up enough at 6500 rpm? (I don't have to rev. to 7000 rpm). My cranking compression is 150 psi.

Erik, You must've missed this one. I don't think he's saying he wants more RPM range here. I think he wants more usable power under 6500. Can't wait to see how your arrogance picks this one apart. In SIMPLE terms I'd appreciate you don't quote me no more. Thanks

Also I would like to point out what is your lobe seperation ? most SBC 383 naturally aspirated cams like a lobe seperation of 104 to 106 degrees. Remember that the 383 is a large displacement motor that can rev, specially if it is internally balanced, so most stock SBC heads only barely get the job done. First off I would get hold of a dynamic compression ratio calculator. Because remember the most important engine power making event is when the intake valve closes. Cam design and static compression ratio work together to give an actual running compression ratio, which is called dynamic compression ratio and is a much more accurate engine building and design tool.

Originally posted by camaro_fever68
Erik, You must've missed this one. I don't think he's saying he wants more RPM range here. I think he wants more usable power under 6500. Can't wait to see how your arrogance picks this one apart. In SIMPLE terms I'd appreciate you don't quote me no more. Thanks

YOU ARE OBVIOUSLY MISTAKEN.I WANT TO TRY AND HELP PEOPLE.CAMARO FEVER68 I WILL STOP QUOTING YOU WHEN YOU STOP MAKING FALSE CLAIMS AND STATMENTS.THERE ARE A LOT OF YOUNG PEOPLE ON THIS FORUM AND WHEN YOU POST B.S. THEY MIGHT THINK IT IS TRUE.REALLY 40-60 H.P. BY HAVING THE CAM GROUND ON 106 L/S AND INSTALLLING IT 4 DEGREE'S ADVANCED.STOP IT YOUR KILLING ME.I WAS BORN AT NIGHT BUT NOT LAST NIGHT.YOU CAN QUOTE THAT IF YOU WANT L.O.L.

Originally posted by erik erikson
YOU ARE OBVIOUSLY MISTAKEN.I WANT TO TRY AND HELP PEOPLE.CAMARO FEVER68 I WILL STOP QUOTING YOU WHEN YOU STOP MAKING FALSE CLAIMS AND STATMENTS.THERE ARE A LOT OF YOUNG PEOPLE ON THIS FORUM AND WHEN YOU POST B.S. THEY MIGHT THINK IT IS TRUE.REALLY 40-60 H.P. BY HAVING THE CAM GROUND ON 106 L/S AND INSTALLLING IT 4 DEGREE'S ADVANCED.STOP IT YOUR KILLING ME.I WAS BORN AT NIGHT BUT NOT LAST NIGHT.YOU CAN QUOTE THAT IF YOU WANT L.O.L.

The only B.S. on this site is you thinking you know it all. If you can't understand simple scavenging you don't know engines. If his lsa would've been about 110 he would gain less hp going to 106 as if it was 108 he would gain even less. 112 is way off and installing it 4 degrees advance would help build more cylinder pressure. Do your homework and post to the sites, don't try to be a know it all when you are nothing but full of B.S. I'm not giving opinions, I'm stating what worked for me in experience, not theory. The problem with people like you is YOU KNOW IT ALL. I haven't seen you actually give helpful advise to anybody. Instead you like to contradict others like Denny and so forth that I know and have seen there advise and have no question that They know what they're doing. If I answer a post on here, it's going to be straight forward what I know will work...Nuff Said, I'm out the pissing contest with you..keep your B.S. and your arrogance to yourself.....

I APOLOGIZE TOO ANYONE AND EVERYONE READING THESE LAST FEW POST. EVERYONE IS ENTITLED TO HIS/HER OWN WITHOUT SOMEONE ELSE BELITTLING THEM. ANYTHING I LIST IN THESE FORUMS WILL BE JUST LIKE MY SIGNATURE HAS SAID FROM THE START. IF I HAVEN'T EXPERIENCED IT OR DONE IT, I WON'T ANSWER IT. I'M STILL LEARNING EVERYDAY AND SOME THINGS I HAVE TO ASK IN THE FORUM ALSO. I'M STILL EXPERIMENTING WITH WATER/ALCOHOL INJECTION AND MY FIRST BLOWER MOTOR.

Originally posted by southerner
Also I would like to point out what is your lobe seperation ? most SBC 383 naturally aspirated cams like a lobe seperation of 104 to 106 degrees. Remember that the 383 is a large displacement motor that can rev, specially if it is internally balanced, so most stock SBC heads only barely get the job done. First off I would get hold of a dynamic compression ratio calculator. Because remember the most important engine power making event is when the intake valve closes. Cam design and static compression ratio work together to give an actual running compression ratio, which is called dynamic compression ratio and is a much more accurate engine building and design tool.

Thanks for the replies guys...Using Wallace Racing's D.C.R. program, it comes up with 8.87:1, with a cranking compression of 181 psi. (My tests show 150 psi dry.) Intake valve closes at 53.0 ABDC, btw. I am considering the Comp cams 280AR or XR274R...any thoughts?

Originally posted by big_G1
Thanks for the replies guys...Using Wallace Racing's D.C.R. program, it comes up with 8.87:1, with a cranking compression of 181 psi. (My tests show 150 psi dry.) Intake valve closes at 53.0 ABDC, btw. I am considering the Comp cams 280AR or XR274R...any thoughts?

Glad to help

Originally posted by big_G1
Thanks for the replies guys...Using Wallace Racing's D.C.R. program, it comes up with 8.87:1, with a cranking compression of 181 psi. (My tests show 150 psi dry.) Intake valve closes at 53.0 ABDC, btw. I am considering the Comp cams 280AR or XR274R...any thoughts?

It all depends on what you want to do with the motor. If you want pro street, which is what you just about have to do with the rest of the combo, you should consider the comp 288AR-6. It requires a 10:1 CR and a 3500 stall. It is a .420 Hi-Tech roller that is designed to be easy on parts. I have been running it for a year in my 383 with no problems. I drive it around town but not on the highway or anything. I think if you go too low on the cam with those heads you will kill power because you will not have enough velocity in those big intake runners. You have to decide what to do in this case. The problem is that if you want a tamer, more streetable engine, you are going to have to start over at the short-block. The heads and intake are performance oriented. I'm running close to the same combo, but with a small converter for the street. I think a 3500 stall would put me in the 10's. I went to a proform 850dp and it didn't help or hurt, so now I got it on a 420sbc.

Originally posted by camaro_fever68
It all depends on what you want to do with the motor. If you want pro street, which is what you just about have to do with the rest of the combo, you should consider the comp 288AR-6. It requires a 10:1 CR and a 3500 stall. It is a .420 Hi-Tech roller that is designed to be easy on parts. I have been running it for a year in my 383 with no problems. I drive it around town but not on the highway or anything. I think if you go too low on the cam with those heads you will kill power because you will not have enough velocity in those big intake runners. You have to decide what to do in this case. The problem is that if you want a tamer, more streetable engine, you are going to have to start over at the short-block. The heads and intake are performance oriented. I'm running close to the same combo, but with a small converter for the street. I think a 3500 stall would put me in the 10's. I went to a proform 850dp and it didn't help or hurt, so now I got it on a 420sbc.

Thanks for the advice. I called Comp Cams earlier today, they recommended a very similar cam, XR280R. I ordered it today. Thanks for all your help, I'll let you know how it worked out.

big_G1, what stall are you running. Stall converters will give you some lower numbers on the dyno torque and HP. The bigger the stall the worse it gets.