Quote:
Or a simple 35 degree decline.
Awesome!!....He should be able to shim the mounts for that last 5 deg................
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| Power Guesstimate my project https://slantsix.org/forum/viewtopic.php?t=63436 |
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| Author: | Tireshredder [ Wed Mar 27, 2019 2:37 pm ] |
| Post subject: | Power Guesstimate my project |
Here’s the deal. I have a 1966 4 door valiant that weighs as much as it did when mfg’d. The slant has been bored 30 over, planning on Comp high energy 252 .435, 215 @ .050, dual offy intake with Weber’s and dutra duals. Valves are stock size, no port work, and the head was only surfaced, no real material taken off. Trans is a stock rebuilt 904, same for the rear end. Tires are 205/60R15. What’s the best guess for net HP and Torque, also best guess for 1/4 mile |
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| Author: | Charrlie_S [ Wed Mar 27, 2019 3:18 pm ] |
| Post subject: | Re: Power Guesstimate my project |
Not going to see a large improvement. Hindsight is 20/20, but while the engine was apart, you really should have milled the head to get in the area of true 8.5-9.0 to 1 compression ratio. That would have complimented the other mods. Depending on rear ratio, I would guess, about 19 sec 1/4 mile. |
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| Author: | Tireshredder [ Thu Mar 28, 2019 10:09 am ] |
| Post subject: | Re: Power Guesstimate my project |
Quote: Not going to see a large improvement. Hindsight is 20/20, but while the engine was apart, you really should have milled the head to get in the area of true 8.5-9.0 to 1 compression ratio. That would have complimented the other mods. Depending on rear ratio, I would guess, about 19 sec 1/4 mile.
Engine is still apart, head disassembled. Started to run out of budget. If I do get the compression up to around 9:1, is that a 15 sec car or am I only cutting .5 off
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| Author: | Dart270 [ Thu Mar 28, 2019 10:59 am ] |
| Post subject: | Re: Power Guesstimate my project |
I would say 18s with stock comp and valves and no porting. That is basically a stock cam. 9:1 might get you 0.5-1 sec if all is tuned well. You really need head porting and a bigger cam and likely a high stall converter if you want a 15 sec car. Lou |
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| Author: | GregCon [ Thu Mar 28, 2019 12:26 pm ] |
| Post subject: | Re: Power Guesstimate my project |
Or a simple 35 degree decline. |
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| Author: | Killer6 [ Thu Mar 28, 2019 4:08 pm ] |
| Post subject: | Re: Power Guesstimate my project |
Quote: Or a simple 35 degree decline.
Awesome!!....He should be able to shim the mounts for that last 5 deg................
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| Author: | Killer6 [ Thu Mar 28, 2019 4:13 pm ] |
| Post subject: | Re: Power Guesstimate my project |
Quote: Quote: Not going to see a large improvement. Hindsight is 20/20, but while the engine was apart, you really should have milled the head to get in the area of true 8.5-9.0 to 1 compression ratio. That would have complimented the other mods. Depending on rear ratio, I would guess, about 19 sec 1/4 mile.
Engine is still apart, head disassembled. Started to run out of budget. If I do get the compression up to around 9:1, is that a 15 sec car or am I only cutting .5 off(EDIT) I should add that that was a '72 Swinger w/AC & 8.75 rear,...3:55's................ |
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| Author: | GregCon [ Thu Mar 28, 2019 7:05 pm ] |
| Post subject: | Re: Power Guesstimate my project |
Quote: Quote: Or a simple 35 degree decline.
Awesome!!....He should be able to shim the mounts for that last 5 deg................
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| Author: | THOR [ Fri Mar 29, 2019 2:02 pm ] |
| Post subject: | Re: Power Guesstimate my project |
I'm with Charlie and Lou here, high 18s to low 19s. Low compression, stall converter and gearing are a huge limitations. I don't think you'll see much more than 10% increase in performance just with the carb, cam and exhaust. You'll feel it, and it will have a broader power band (which is very helpful!), but top end numbers won't be highly affected. Did you buy that Dual Weber intake from Bryce? ~THOR~ |
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| Author: | slantzilla [ Fri Mar 29, 2019 2:56 pm ] |
| Post subject: | Re: Power Guesstimate my project |
IF you can get those carbs to work well, it should run high 17's all day. |
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| Author: | SpaceFrank [ Wed Apr 03, 2019 3:09 pm ] |
| Post subject: | Re: Power Guesstimate my project |
Shaving .060-.080" off the head shouldn't cost you more than $100 and is generally well worth the expense. Granted you should really take all the required measurements to know exactly what your starting SCR is, so you're not just shooting in the dark. Oversized valves will require more expensive machine work (say $300-400) plus the cost of the valves, which are getting harder to find unless you find an unused set from someone on this forum. Port work, which you should really do to take advantage of the bigger valves, is fairly time-consuming if you do it yourself and very expensive if you don't. If you haven't bought that aftermarket cam yet, I'd skip it. Instead, once you know your final SCR, get a recommendation from someone like Dart270 on an Oregon Cam grind. If your stock cam is in good condition, getting a regrind from them is something like $85 plus shipping. (All the dollar figures in this post are based on my own limited experience; your mileage may vary.) (Edited much later to fix a glaring typo) |
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| Author: | Killer6 [ Wed Apr 03, 2019 3:36 pm ] |
| Post subject: | Re: Power Guesstimate my project |
215deg@.050 isn't anywhere near a stock bumpstick, My DC276/.490 purple-shaft checks around 219@.050,......the lift isn't much more because a stock port/valve won't be delivering much more at .500 so it is probably a smooth profile. Certainly better than a stock cam tho',...the real issue is whether this cam has the oil pump/dizzy drive gear hardness issue corrected.................. |
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