looking for more hp

General engine tech -- Drag Racing to Circle Track

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fishman
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looking for more hp

Postby fishman » Wed Oct 01, 2008 12:16 am

I am looking for about 30 more horse power from my combo. Does anyone have any ideas without costing alot of money.

Motor dart sbc stroked 383
6 inch rods
mahle 13.52 compression ratio running c12 fuel
heads are afr cnc 210 that have been ported short turn radius
intake is super victor ported
carb is holley 4150 flowing around 1000 cfm with 1 inch open spacer
headers are 1 3/4 ceramic coated with 3 inch collector built to pipemax numbers
cam is a solid roller 108 264 and 272 duration with 640 lift
crane gold rockers 1.6 ratio.

Tranny is a jw glide with 1.74 first gear and 8 inch 4900 rpm stall which is to tight and sending in to get loosened up...peak torque on motor dyno was 5100-5300 rpm so looking to get it around 5700-5900 stall

rear gears are 4.86 with 32x14x15 tires.....thinking about going to 4.56 gears as on dyno peak horse power was around 6800 rpm....at 7000 rpm was down maybe 5 or 6 hp and at 7300 rpm down about 15 horse.

car weight with me in it is 2460

took car to sea level this weekend from our track elevation is 2300 feet and corrected at 2900 feet i ran 10.15 and at sea level corrected 900 feet car ran 9.81 ....the torque stalled 500 rpm more and picked up .05 in my 60 foot so i know i need at least 500 more stall.

I want car to run in the nines at our track and i think the torque will give me at least 1/10 gain so need at least another 1/10 gain from somewhere else.


Thanks for the input and sorry for long winded story....was trying to give enough info as possable
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Postby ou812 » Wed Oct 01, 2008 12:25 am

I would go to a cam with numbers like this: 270-278@.050, 106 lobe center and around .720 lift. Shift it higher, and keep the gear you have. It'll want more gear, but try it first.
You may end up wanting an 1 7/8 header to work in that rpm range. If you want low rpm HP, you'll need a bigger engine IMO!
Brian

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Postby CamKing » Wed Oct 01, 2008 9:24 am

If you want to pick up 30+ HP without moving the power up past 7,300, you need to go to a 1 3/4" stepped to 1 7/8" header(or a straight 1 7/8) with a 3.5" collector.
I'd also recommend my cam part# R80432-80424-109
269/272 @ .050"
.432"/.424" Lobe lift
109 LSA
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Postby Strange Magic » Wed Oct 01, 2008 10:25 am

took car to sea level this weekend from our track elevation is 2300 feet and corrected at 2900 feet i ran 10.15 and at sea level corrected 900 feet car ran 9.81 ....the torque stalled 500 rpm more and picked up .05 in my 60 foot so i know i need at least 500 more stall.


No.

You picked up 60ft because you are making more torque and hp from the density altitude change, and yes a side effect would be an increase in stall due to the torque increase.

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Postby jeffmckc » Wed Oct 01, 2008 11:04 am

I would get rid of that huge tire your hauling down the track
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Only 30 HP?

Postby UDHarold » Wed Oct 01, 2008 12:41 pm

As usual, Mike and I don't always agree on everything, but here's my suggestion:
300/308@.020, 272/280@.050, 197/203@.200, .4544"/.4544" lobe lift, .727"/.727" gross valve lift, .710"/.710" net valve lift, and 106 LSA.
In the old UD days, I ran 279/283 at .050, .640"/.640" gross lift with 1.5s, and 106 LSA, for 9.60s in 2800-lb cars, 9.10s in 2300-lb cars, and 8.70s in 1750-lb cars, all with 383s like your's.
This one should take care of your altitude problem and where you want peak BHP.
As always, you need a good 240-250gph pump and 1/2" fuel line from tank to carb.

UDHarold

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Postby CamKing » Wed Oct 01, 2008 1:35 pm

Harold's pick will make more power then mine.
I was looking at making an extra 30HP without having to turn it harder, or increase the lift too much.
I saw where money was an issue, so I stayed away from a design that would require other upgrades.
Mike Jones
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Postby Strange Magic » Wed Oct 01, 2008 2:01 pm

I would get rid of that huge tire your hauling down the track


Yep. It is not necesarry. A 31.25 x 12.5 Phoenix is all you need on a 12 inch wide rim for your application. You will pick up big mph and et gains. You will probably flip it over with this tire rim combo, soo make sure you have some bars on it.

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Postby fishman » Wed Oct 01, 2008 5:29 pm

money does become a issue.....yes

The headers are brand new and custom made...cost me $1500...so new headers are out of the question

Replacing the back rims and tires are another money issue as the tires and rims are brand new, i can't justify replacing again and losing a bunch of money

The torque convertor was made to tight when i got it and left it that way for the year as wanted to have some fun, i went to sea level racing to see how much more stall i did need and i am guessing even with 500 more stall at sea level i need a little more as i was leaving on the flash.

The cam is probably the most sensable thing for me as i am on a budget and i am spending money on front end parts and a new fiberglass hood...torque vertor loosening up.

I realize you guys are trying to help me out, but i am giving you more information on my situation....that way the info you recommend will fit me better....so would you say with a new cam with out any changes i will gain the horse power i want?
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Postby CamKing » Wed Oct 01, 2008 6:17 pm

fishman wrote:so would you say with a new cam with out any changes i will gain the horse power i want?

As long as your springs can handle the new cam, you shouldn't need any other changes.

Your headers are too small, but they won't cost you much power at altitude. They'll be more of a restriction at sea level.
Mike Jones
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fishman
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Postby fishman » Wed Oct 01, 2008 10:13 pm

CamKing wrote:Harold's pick will make more power then mine.
I was looking at making an extra 30HP without having to turn it harder, or increase the lift too much.
I saw where money was an issue, so I stayed away from a design that would require other upgrades.


u r saying you have a camshaft that will give me 30 more hp without turning the motor any harder........the car does seem to really lag the last 100 feet or so......a little more hp and a bigger cam will straighten that out...thanks
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Postby MELWAY » Wed Oct 01, 2008 10:51 pm

mill the heads for 14:1comp and put UD harolds cam in it...
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Postby rustbucket79 » Wed Oct 01, 2008 10:56 pm

What is your current trap RPM? If you are only down 15 HP at 7300, I would be looking at gearing for a 7500 trap RPM, to gain ET the first part of the track and help utilize those big slicks. 5500 to 6000 stall once the gearing is optimized should help, and keep you out of the engine for the time being. Change the cam when it's time to replace the lifters and springs.

Keep in mind a quick ET is an ego requirement, a win light can be had at any ET if the car is dialed correctly. ;)

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Postby Scott H » Wed Oct 01, 2008 11:58 pm

rustbucket79 wrote:What is your current trap RPM? If you are only down 15 HP at 7300, I would be looking at gearing for a 7500 trap RPM, to gain ET the first part of the track and help utilize those big slicks. ;)


Bingo! If it were my car, it would have 5.2X to 5.3 rear gears. I'll bet he could darn near do it with the gear change alone.

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Postby fishman » Thu Oct 02, 2008 12:20 am

Scott H wrote:
rustbucket79 wrote:What is your current trap RPM? If you are only down 15 HP at 7300, I would be looking at gearing for a 7500 trap RPM, to gain ET the first part of the track and help utilize those big slicks. ;)


Bingo! If it were my car, it would have 5.2X to 5.3 rear gears. I'll bet he could darn near do it with the gear change alone.


I use to have 5.14 gears in the car and i changed to 4.86 and the car picked up et it was falling over on the top end.

Trap speed is on my tach is around 6900 rpm...but i think it is more like 6800 rpm

I am not crazy about reving it to high, would rather the motor last and try to keep it around 7000 rpm.

the new torque will change the car but it still might need a diffrent cam as this one seems to be pretty lazy the last 100-150 feet....still better then when i had 5.14 gears the last 250 feet sucked
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