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#1
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Horsepower increase ?
I'm considering replacing my 463" with a 495" short block.
I have about 580 rear wheel HP now. Any guess how much I might gain. Thanks, OGR
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3 Generations of "Beach Boys Racing" ! Everybody knows somthin. Nobody knows everything ! 1st time on a dragstrip, 1964. Flagstart ! "Thanks for the entertainment." "Real Indians Don't Wear Bowties" |
#2
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Definitely a TQ increase, thus HP increase with a 495 vs 463, regardless of carb, cam, heads and manifolds. - Cpt Oblivion
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#3
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Depends on cam and topend but possibly peak hp gain of zero, just a good gain in average power.
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#4
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When we switched the Grocery Getter from 455 to 540, but kept the same e-heads and cam, it was hard to measure any gain in ET but the added torque was terrific for burnouts! Changing to Tiger heads really woke up the horsepower.
Eric
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"Everybody has a plan until they get punched in the mouth" noted philosopher Mike Tyson Life begins at the end of your comfort zone. The mind, once stretched by a new idea, never returns to its original dimensions. |
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#5
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If you keep the same top end parts you will see no HP increase, or nothing much to write home about anyway!
Right now if you where making 580 flywheel hp your using 280 cfm out of whatever the peak air flow number is that your heads flow and or intake can pass on to the heads. What will happen with the 7% cid increase is that your rpm of peak torque and Hp will take place 7 % sooner in rpm, and as posted above you will see a torque increase due to the added cid. If at this point you want a noticeable Hp increase you can go for more valve lift to access more flow if your heads have such left, and this can be done by means of a cam change or higher ratio rockers if you want to keep the head porting as it is now. If you want to pull the heads and mill them for a full 1 point of compression increase you would pick up 1.5% more hp using flywheel numbers, or like 9 more hp at best. Why is it that your using rear wheel Hp numbers anyway, are you just going by your ET/ mph?
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I do stuff for reasons. Last edited by 25stevem; 01-29-2023 at 03:59 PM. |
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#6
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I punched the number into a program for my High Port heads on my current 461. Then punched them in with the same heads on a 540.
HP was the same but the RPM range dropped for the 540. |
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#7
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I went from 461 to 499 ci with the same cam and heads and gained 0.12 in ET and about 1 mph.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
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#8
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I gotta say that I learned a lot from this Thread question. Explains to me why some folks were in the 10's with 400s about 40-30 years ago, while i was doing 12s and "Headed" into the lowest 11s (pun intended).
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12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
#9
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The other detail here to having a performance gain while hp does not really change is if the percentage of torque increase is greater then the percentage of internal friction increase of the larger motor.
If there’s still a net torque gain left over then the new motor will gain rpm faster then the old one until the rpm of peak torque is reached. This faster gain in rpm after shifts is what will make for a increase in ET, but with little change in mph. As always this all hinges on applying this new found extra torque down to the track.
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I do stuff for reasons. |
#10
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Other details that can take place with a increase in ET which of course produces a increase in G force on the car during a pass and especially at the green light can be finding out the limit of what you fuel pressure can over come in terms of G forces.
At 2 Gs which is like a car that can run in 9s in the 1/4, a fuel system will drop .3 psi per ft of run that it makes getting up to the carb inlet.
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I do stuff for reasons. |
#11
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Why is it that your using rear wheel Hp numbers anyway, are you just going by your ET/ mph?
I used the Wallace calculator. 9.88 @ 133. 3150 #
__________________
3 Generations of "Beach Boys Racing" ! Everybody knows somthin. Nobody knows everything ! 1st time on a dragstrip, 1964. Flagstart ! "Thanks for the entertainment." "Real Indians Don't Wear Bowties" |
#12
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My guess is you will gain about a tenth and half in et.
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Come take a ride http://www.youtube.com/watch?v=P7Y8Awfk2I0 2008, 2013, 2015, 2016, 2019 Central Il Dragway Mod track champion and 2015 IHRA Div 5 Mod champion |
#13
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Remember by using the same top end he will be gaining compression with the extra cubes
under the same chambers
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If your not at the table you're on the menu A man who falls for everything stands for nothing. |
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#14
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My experience was the opposite way. I broke the 4.5” M/T crank in my 495 and put the same cam, heads and intake/carb on a 4.25” stroke 467” engine and went the sameET within a tenth of a second. Heads were 320cfm Edelbrocks with a .440 lobe Butler roller cam and Victor/ Dominator intake and carb.
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#15
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( This Thread reminds me that ) The Bore increase is worth more HP than the Stroke increase.
4.351" Bore seems like a practical parameter-goal. Hey Olds 403s in T/As. 403s still lack a strong block right? |
#16
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Quote:
Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#17
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Sounds like the HP/ET gain is not worth the $$$$/Labor.
Thanks for your replies gentleman. OGR
__________________
3 Generations of "Beach Boys Racing" ! Everybody knows somthin. Nobody knows everything ! 1st time on a dragstrip, 1964. Flagstart ! "Thanks for the entertainment." "Real Indians Don't Wear Bowties" |
#18
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Quote:
did you notice any more traction related issues? did you make carb change? i'm looking to gain more in the mid/top end, don't want any more low end traction issues, or harder hitting torque resulting in parts breakage (well, to the best i can) i've been leaning towards a headswap, but.... i could only image the fun factor of more low end torque (on the street for such easy burn outs, but tires getting VERY expensive, hence the higher end range desire) |
#19
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Quote:
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
#20
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Quote:
I replaced a trick TCI converter with a PTC converter that was less expensive but gained ET in the middle of the track. Same 60 foots and MPH but over a tenth quicker. Lane from PTC spec,ed it for me. |
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