Excellent video, well planned and executed. I used to have a high compression engine, and I know about the diminishing return. I diminished my bank account having to buy starters over and over, then finally a Tilton Superstarter.
As a big block ford guy, I’ve driven old dirty big ci engines, in big heavy convertibles. Detonating has been an issue, I look forward to building my scj to clean big power. Your video is concise and easy to follow. Thank you!
Enjoyed the video very much and I also enjoyed the video you did on "quench." I would like your opinion on how much you think the correct or incorrect quench affects detonation. Im looking forward to the next video. Thanks Allan
so i have a question and example to verify by someone with more experience as i do. I have a 440 mopar rb and want to stroke it to 505 with a (i think good) 10.5 static CR and aluminium heads cam should be street oriented and more on torque so i think a (Howards Cams Retrofit Hydraulic Roller Camshafts 720555-10) Duration at 050 inch Lift: 228 int./234 exh. lobe sepa. = 110 with this cam i get a calculatet Intake closing after bottom dead center (ABDC) of 44 deg so in the wallace calc. i all of this in with (stroke 4.25/ bore 4.32 rod lengh 7.1/ alt 0/boost 0) the result is 204 psi cranking or 9.5 dynamic CR wich is way to high for 91 octane or am i wrong??
it feels false to go under 10:1 static CR in my head with a static CR of 9.5 i would land perfectly on 180 psi but the cam says 9.5+ CR so it would be the lower limit.
Thanks in advance i am from germany and have a dodge challenger 440 1972 so errors in my english shall be forgiven 😉
Hey allan, could you elaborate on the connection of the intake valve closing event with compression .I believe this would show up in the static compression ratio and the cranking compression PSI. I"m asking because I need to select a cam for my stroker 360 mopar [408 cid]. I have trick flow 190 heads ,harland sharp 1.6 rockers.A scat rotating assy with 20 cc dished icon pistons giving a compression ratio of 10.4 [.39 thou head gasket] 60 cc chambers. The cam will be a hydraulic roller for 90% street driving #3500 pound CUDA, 2800 stall converter and 4.30 gear.
You certainly gave me a lot to think about and try on my Oldsmobile. I’m running a carburetor so that can change my mixture anytime and I’ll have no idea. I will try those ignition changes to hopefully get rid of the detonation problem.
I have had good results at around 9:1 dynamic compression with iron heads and 9.5:1 with aluminum. The 10.25:1 static, 9:1 dynamic 350 with iron Vortec I am running performs great on 87 octane. The 11:1 383 with aluminum heads is at 9.5:1 dynamic and performs best on 91+ although it will run all day long on 87 with the timing at 30* total at WOT.
Well said. I have been a proponent of all the concepts you touched on. I am definitely still learning too. I have a Chevy small block with an unknown cam, bore, everything. It's a rebuilt 350 from Summit. But since I also have the OE block I'll eventually build it for the car. I think I'm going to check the block and if it passes muster I'd like to design it either as OE stock, or with a 3.75" stroke and aluminum heads so I can run above 10:1 to make good power. I may also see if it would function with the OE heads on that cam and stroke. That way it could go back to something resembling stock by reinstalling the factory top end. I realize that's over designing, But it's hot rodding right? With me, you are preaching to the choir, but I'll follow to see what I may have missed or not considered. Or just to see the details of your builds. Please touch on piston ring materials, block hone values and their meanings, and bearing materials. I think a guy like you could clarify using roller cams in flat tappet engines too.
I’ve been seeing a lot of people run boost on engines at like 10.8:1. How are they doing that? I always thought you had to be at like 9.0:1 for pump gas. Is there a rule of thumb?
Thanks for the information I have a 65 tempest with a 400 GTO engine and sniper EFI stock bore and small cam runs great giting ready for a rebuild what do you suggest on pistons and bore trying to get it one 10 s
Big Thx for taking Time putting up one of the best Organized, Intelligent & Helpful '60's –'70's oriented "Muscle Car" era High Perf engine channels !! …..Detonation engine Protection while running on the Octane/CR edge is real Challenge with so Many variables & build Mistakes sometimes difficult to correct for customer & some Oem brands worst than others….Late '50's & all '60's Pontiac Oems seem Prone to Pre-Ignt & Detonation more than other GM's….Definitely engine builders taking Chances with Over 180 Psi crank numbers…..Can Detonation happen in the Top Rpm range where it's Harder to Hear ??
Hi, i have 185 psi cranking dry with 5 degrees advanced camshaft and want to retard same cam to 4 degrees retarded , 9 degree change-what psi do you think i will end up? 150 ? also , the 3 Pontiacs you are building , will you install them with no advance or retard?
Good information! Didn’t know anything about the heat range with spark plugs. I’ve messed with cars and engines my whole life never heard of a Ct400 , no clue what that is. Must not be a USA engine. Thanks for the information! Good video!
Great stuff. Does cylinder volume affect the likelyhood of detonation all else being equal? I'm building a 2 liter L6, with a modest 166psi dynamic cranking pressure, and a low volume to pressure ratio of 44. I'm having trouble finding info on how to use that figure.
I have a 1992 Nissan 300ZX with cold cylinder pressure of 180psi….the engine has 188k miles….so there's that?
how about quench?
Excellent video, well planned and executed. I used to have a high compression engine, and I know about the diminishing return. I diminished my bank account having to buy starters over and over, then finally a Tilton Superstarter.
As a big block ford guy, I’ve driven old dirty big ci engines, in big heavy convertibles. Detonating has been an issue, I look forward to building my scj to clean big power. Your video is concise and easy to follow. Thank you!
Thank you for a good video. I was looking at how much compression should you run in a prochrched street/strip engine.
11.5 or so w good aluminum heads, proper quench
Enjoyed the video very much and I also enjoyed the video you did on "quench." I would like your opinion on how much you think the correct or incorrect quench affects detonation. Im looking forward to the next video. Thanks Allan
so i have a question and example to verify by someone with more experience as i do.
I have a 440 mopar rb and want to stroke it to 505 with a (i think good) 10.5 static CR and aluminium heads
cam should be street oriented and more on torque so i think a (Howards Cams Retrofit Hydraulic Roller Camshafts 720555-10)
Duration at 050 inch Lift: 228 int./234 exh. lobe sepa. = 110
with this cam i get a calculatet Intake closing after bottom dead center (ABDC) of 44 deg
so in the wallace calc. i all of this in with (stroke 4.25/ bore 4.32 rod lengh 7.1/ alt 0/boost 0)
the result is 204 psi cranking or 9.5 dynamic CR wich is way to high for 91 octane or am i wrong??
it feels false to go under 10:1 static CR in my head
with a static CR of 9.5 i would land perfectly on 180 psi but the cam says 9.5+ CR so it would be the lower limit.
Thanks in advance
i am from germany and have a dodge challenger 440 1972 so errors in my english shall be forgiven 😉
Hey allan, could you elaborate on the connection of the intake valve closing event with compression .I believe this would show up in the static compression ratio and the cranking compression PSI. I"m asking because I need to select a cam for my stroker 360 mopar [408 cid]. I have trick flow 190 heads ,harland sharp 1.6 rockers.A scat rotating assy with 20 cc dished icon pistons giving a compression ratio of 10.4 [.39 thou head gasket] 60 cc chambers. The cam will be a hydraulic roller for 90% street driving #3500 pound CUDA, 2800 stall converter and 4.30 gear.
You certainly gave me a lot to think about and try on my Oldsmobile. I’m running a carburetor so that can change my mixture anytime and I’ll have no idea. I will try those ignition changes to hopefully get rid of the detonation problem.
I have had good results at around 9:1 dynamic compression with iron heads and 9.5:1 with aluminum. The 10.25:1 static, 9:1 dynamic 350 with iron Vortec I am running performs great on 87 octane. The 11:1 383 with aluminum heads is at 9.5:1 dynamic and performs best on 91+ although it will run all day long on 87 with the timing at 30* total at WOT.
Well said. I have been a proponent of all the concepts you touched on. I am definitely still learning too.
I have a Chevy small block with an unknown cam, bore, everything. It's a rebuilt 350 from Summit.
But since I also have the OE block I'll eventually build it for the car. I think I'm going to check the block and if it passes muster I'd like to design it either as OE stock, or with a 3.75" stroke and aluminum heads so I can run above 10:1 to make good power. I may also see if it would function with the OE heads on that cam and stroke. That way it could go back to something resembling stock by reinstalling the factory top end. I realize that's over designing, But it's hot rodding right?
With me, you are preaching to the choir, but I'll follow to see what I may have missed or not considered. Or just to see the details of your builds. Please touch on piston ring materials, block hone values and their meanings, and bearing materials.
I think a guy like you could clarify using roller cams in flat tappet engines too.
I’ve been seeing a lot of people run boost on engines at like 10.8:1. How are they doing that? I always thought you had to be at like 9.0:1 for pump gas. Is there a rule of thumb?
Thanks for the information I have a 65 tempest with a 400 GTO engine and sniper EFI stock bore and small cam runs great giting ready for a rebuild what do you suggest on pistons and bore trying to get it one 10 s
Big Thx for taking Time putting up one of the best Organized, Intelligent & Helpful '60's –'70's oriented "Muscle Car" era High Perf engine channels !! …..Detonation engine Protection while running on the Octane/CR edge is real Challenge with so Many variables & build Mistakes sometimes difficult to correct for customer & some Oem brands worst than others….Late '50's & all '60's Pontiac Oems seem Prone to Pre-Ignt & Detonation more than other GM's….Definitely engine builders taking Chances with Over 180 Psi crank numbers…..Can Detonation happen in the Top Rpm range where it's Harder to Hear ??
Hi, i have 185 psi cranking dry with 5 degrees advanced camshaft and want to retard same cam to 4 degrees retarded , 9 degree change-what psi do you think i will end up? 150 ? also , the 3 Pontiacs you are building , will you install them with no advance or retard?
Sorry ,ment to say the connection with dynamic compression ratio and the intake closing event.
Steel heads?
Most cylinder heads are either cast iron, or aluminum. Where do steel heads come from? Please explain.
Thank You….
Great info sir!!!
Good information! Didn’t know anything about the heat range with spark plugs. I’ve messed with cars and engines my whole life never heard of a Ct400 , no clue what that is. Must not be a USA engine. Thanks for the information! Good video!
Always used factory spec plugs
Power Nation already did this.
Great stuff. Does cylinder volume affect the likelyhood of detonation all else being equal? I'm building a 2 liter L6, with a modest 166psi dynamic cranking pressure, and a low volume to pressure ratio of 44. I'm having trouble finding info on how to use that figure.
Curious about twin-plug heads as seen on Porsches, Mercedes-Benz and Harley’s some say it enables higher compression?