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Been building this 383 for a couple of years now and I'm about ready to pull the old motor. I'm super excited to have some real power in my 77. I'm estimating just over 500 ft/lbs of torque and around 430hp. May even get it on the engine dyno just to see.
Wow someone finally bought the AFR Vortecs! I'm pretty excited to see the results, too. Please get it on an engine dyno if you can; there's just not enough data (none?) on people using these heads.
I am curious how you ended up with an estimate of 500ft lbs given that there just doesn't seem to be much / any dyno data on these heads. My understanding is that they're not just an aluminum, CNC ported version of the Bowtie Iron Vortecs, but they're a modified AFR 180 such that they fit the vortec intake ports (Although they seem to have different exhaust flow so I don't get that...)
If you added this intake to your build, you've got the build I've been dreaming of: https://dallas.craigslist.org/ftw/pts/6100029558.html Get the FIRST intake, some huge sticky tires, and generate enough torque to re-enact the plot from Superman 2 and spin the earth backward to go back in time.
Torquey beast! Can't wait to see the results!
Naturally aspirated SBC with big block torque #'s -that's the dream!
Adam
Last edited by NewbVetteGuy; 06-06-2017 at 11:31 AM.
Watch for detonation issues with that much compression and a relatively short duration cam.
Shoot... That's a good point: OP: Have you calculated your dynamic compression ratio?
Have any plans to help mitigate detonation risk with that combo?
(Cold Air Intake, Good aluminum radiator, low temp thermostat, separate trans cooler, oil cooler, etc..?? -Just retard the cam a couple of degrees and have octane booster on hand for when it gets hot outside?)
Adam
Last edited by NewbVetteGuy; 06-06-2017 at 12:36 PM.
I have 9.7:1 compression in my 383 (iron Vortec heads). When I had a cam with 218/224 duration it would ping in part throttle, up hill type operation. I have forged pistons so that eased my mind a little.
Been wanting to see someone use those heads, havent seen one build yet let us know how this works out
Going to be one torquey sob!
I will try to keep the progress updated on this thread as much as possible.
Originally Posted by NewbVetteGuy
I am curious how you ended up with an estimate of 500ft lbs given that there just doesn't seem to be much / any dyno data on these heads.
I've run a ton simulations using similar flowing heads and cams. Nothing with my exact grind but close enough to know what will change with my wider LSA. These heads flow as good if not slightly better for my application than their 195cc heads.
Originally Posted by BKbroiler
Watch for detonation issues with that much compression and a relatively short duration cam.
Yes, detonation would normally be a bit of a worry. I don't know how it will handle timing either. Fortunately, race fuel at the pump is right around the corner from my house. Detonation shouldn't be a problem after that. I am however worried about those Hypereutectic Pistons though...
Originally Posted by NewbVetteGuy
Shoot... That's a good point: OP: Have you calculated your dynamic compression ratio?
Have any plans to help mitigate detonation risk with that combo?
(Cold Air Intake, Good aluminum radiator, low temp thermostat, separate trans cooler, oil cooler, etc..?? -Just retard the cam a couple of degrees and have octane booster on hand for when it gets hot outside?)
Adam
Yes. DC and cranking pressure is up. 9.69 DC 204ft/lbs cranking pressure. There is a fantastic little box from Daytona-Sensors that gives full control of timing. I will likely need to rework my entire spark delivery system with this new engine.
Originally Posted by BKbroiler
I have 9.7:1 compression in my 383 (iron Vortec heads). When I had a cam with 218/224 duration it would ping in part throttle, up hill type operation. I have forged pistons so that eased my mind a little.
Hopefully the aluminum AFR heads will be a bit more forgiving than the iron GM. What octane fuel did you run? Full roller or flat tappet? What was your timing curve? All this info would really help me out with my initial setup.
FWIW I have a 383 with 9.7 compression and 222 degrees of duration on 110 LSA, and aluminum heads. I have no issues with detonation on 92 octane since I removed the EGR system.
FWIW I have a 383 with 9.7 compression and 222 degrees of duration on 110 LSA, and aluminum heads. I have no issues with detonation on 92 octane since I removed the EGR system.
Is that Static Compression or Dynamic Compression?
Yes. DC and cranking pressure is up. 9.69 DC 204ft/lbs cranking pressure. There is a fantastic little box from Daytona-Sensors that gives full control of timing. I will likely need to rework my entire spark delivery system with this new engine.
Wow! That's a monstrous dynamic compression ratio, even for an aluminum head! (I'm kinda worried for you right now.)- I'm also kinda excited because if you can fight off detonation that torque really should be amazing! Get this motor in your car already! lol!
Plans for a cold air intake? David Vizard says every 8 degrees of intake air temp reduction is a 1 octane equivalent increase in detonation resistance. IMHO: Get every bit of power and timing you can safely get by focusing on cooling- focus on air temp first. AKA You need a CAI. (If you go into your DCR calculator and simulate retarding the cam by 3 degrees, I think the DCR will look much safer.
Adam
Last edited by NewbVetteGuy; 06-06-2017 at 03:40 PM.
for an occasional driver wondering if running a cool can would help things alone todays gas (at least out here) sucks. think he will probably be ok....get your fueling right should be safe.
for an occasional driver wondering if running a cool can would help things alone todays gas (at least out here) sucks. think he will probably be ok....get your fueling right should be safe.
What's a cool can?
By "Get your fueling right" -you mean "dial-in a rich mixture that wastes fuel to make up for having too high of a dynamic compression ratio?" (because that's how I'm interpreting that statement)
[edit] I just looked up what a cool can is; you're joking, right?
P.S. Let's all remember that the OP is in Texas; it's not exactly cold air territory.
Adam
Last edited by NewbVetteGuy; 06-06-2017 at 03:39 PM.
FWIW I have a 383 with 9.7 compression and 222 degrees of duration on 110 LSA, and aluminum heads. I have no issues with detonation on 92 octane since I removed the EGR system.
If you're talking about a 9.7 static compression ratio, then you're going to be below an 8.0:1 DCR; the OP is at 9.7 DCR -meaning that from the time the intake and exhaust valves are closed until top dead center he's compressing the air-gas mixture at an actual 9.7:1 ratio prior to spark ignition (with no advance(?)).
Ax: I've got a PipeMax license, if you post all the data you're using for your DCR calculation (# of inches down the hole for the piston, gasket thickness, etc..) I can plug all your engine data in and see what it estimates for cylinder temp and octane requirement (although it sounds like you might have already done that as you've got your cylinder pressure calculation already)-- I'm not sure what air temp or cooling that PipeMax assumes but I could post the question over on the PipeMax forums...
mean using an o2 sensor to tune A/F as you know too rich is as bad as too lean.
cool can https://www.summitracing.com/parts/mrg-1350
ice, ice packs etc plumb in after fuel pump before carb
have run that same cam with 11:1 and not so great heads no pinging problems.
If you're talking about a 9.7 static compression ratio, then you're going to be below an 8.0:1 DCR; the OP is at 9.7 DCR -meaning that from the time the intake and exhaust valves are closed until top dead center he's compressing the air-gas mixture at an actual 9.7:1 ratio prior to spark ignition (with no advance(?)).
Ax: I've got a PipeMax license, if you post all the data you're using for your DCR calculation (# of inches down the hole for the piston, gasket thickness, etc..) I can plug all your engine data in and see what it estimates for cylinder temp and octane requirement (although it sounds like you might have already done that as you've got your cylinder pressure calculation already)-- I'm not sure what air temp or cooling that PipeMax assumes but I could post the question over on the PipeMax forums...
Adam
That would be fantastic, Adam. Thanks!
4.03 bore
5.7 rod
.041 gasket (fel-1003)
stock deck
65cc chamber
+5cc volume from piston
Is that Static Compression or Dynamic Compression?
That's static. You can reduce your dynamic compression by retarding the cam. I would suggest you might want to consider more cam but I know what that roller costs. Since you have concerns, why not install a two piece timing chain cover. At least it will make it a lot easier if you have to change the cam or the cam timing later.
That's static. You can reduce your dynamic compression by retarding the cam. I would suggest you might want to consider more cam but I know what that roller costs. Since you have concerns, why not install a two piece timing chain cover. At least it will make it a lot easier if you have to change the cam or the cam timing later.
I did install a two piece. The billet one from comp. Retarding by 4 degrees doesn't do much on a cam that short. I knew what I was getting in to when I designed that cam. However, since then, the drag strip next to my house has closed down and race fuel may be getting a bit scarce and pricier. Bad timing for sure.
Either way, I'm going to initially tune at 32 Degrees on 93/94 octane and see how she acts. If I need to run a mix of 100 octane, oh well. I don't want to give up on my dream!
4.03 bore
5.7 rod .041 gasket (fel-1003)
stock deck
65cc chamber
+5cc volume from piston
What else.... I think that's it.
If your pistons are down in the hole .025", like most stock deck engines are, that is not good. It gives you a squish (piston to head clearance) of .066" which will not help prevent detonation at all. You would be much better off with the squish tighter and more compression. The tighter the squish, the better for preventing detonation. I would never run looser than .040". My engine in my signature is set at .034".
A tight squish will create more turbulence in the combustion chamber, squeezing everything out from the quench areas in towards the chamber, making a more homogenous mixture and a more even burn, which helps eliminate detonation.
What is the advertised duration on that cam? Also, what's your LSA and ILC?
I agree 100% on squish, I'm at 0.037" myself. Haven't plugged the numbers in and haven't the time right now, but compression quoted sounds high given the specs discussed?
06-05-2017, 10:07 PM
383 Stroker Build, AFR Vortecs, Full Roller
