400 ci shift point
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Lead Driver
Joined: Nov 2000
Posts: 6,624
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From: Albuquerque
400 ci shift point
My 400 make 435 hp/ 510tq on paper. Hydro roller good to 5500. I'm not sure where my shiftpoint should be. Keeps pulling to 5400rpm but not sure if it's passes the hp peak.
Anyone with similar engines?
Anyone with similar engines?
Super Moderator
Joined: Apr 2004
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Did your paper say what RPM you were getting your power?
You must have put in new valve springs--any recommendation on those for max rpm?
Any rod work? ARP bolts? Other anti-grenade items?
You are probably good to 5500 when needed....
You must have put in new valve springs--any recommendation on those for max rpm?
Any rod work? ARP bolts? Other anti-grenade items?
You are probably good to 5500 when needed....
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Lead Driver
Joined: Nov 2000
Posts: 6,624
Likes: 342
From: Albuquerque
Should be good to 6000+ mechanically. It will keep pulling to 5500 if I let it, but I might be too far past the hp peak. Can't fine my old desktop dyno chart at the moment, that would help. Looking for anyone with a "similar" set up to compare with.
Again, talking about a 1/4 mile run.
Again, talking about a 1/4 mile run.
Hotshot
Joined: Jul 2020
Posts: 10,359
Likes: 2,592
From: Near Salt Lake City
Do not deal with magic paper
Deal with a chassis dyno
Then you will know actual numbers and the RPM of those numbers
I think you are close at 5400 RPM but you want exact and to be sure
That means find a chassis dyno close to you and have it tested
Good luck
Deal with a chassis dyno
Then you will know actual numbers and the RPM of those numbers
I think you are close at 5400 RPM but you want exact and to be sure
That means find a chassis dyno close to you and have it tested
Good luck
Cargo Master
Joined: Oct 2020
Posts: 2,657
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Dyno numbers will tell you the shape of the torque and HP curves but they really won't tell you much about the ideal shift point. You can only determine that at the track by running a few passes trying different shift points to see what's best. Sometimes shifting way past the peak can be the best and sometimes just the opposite and you never know unless you experiment.
Hotshot
Joined: Jul 2020
Posts: 10,359
Likes: 2,592
From: Near Salt Lake City
Yes Trial and error I shift quick sometimes and win easier than rodding the hell out of my unit
Used to race the hell out of my 69 Z28 never lost to a big block anything
Well I take that back, there was a 383 Magnum Cuda I used to loose to once in a while
And a built 460 Rancheroo gave me some trouble once
Used to race the hell out of my 69 Z28 never lost to a big block anything
Well I take that back, there was a 383 Magnum Cuda I used to loose to once in a while
And a built 460 Rancheroo gave me some trouble once
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Cargo Master
Joined: Oct 2020
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I don't know how true it is for drag racing but usually the more restricted the induction the greater amount you have to over run the power peak which seems weird but I guess it's just required to get the best average power and acceleration. A good example is circle track racing with a 2 barrel carburetor. A 355 with a 4412 will typically power peak at about 6100rpm yet at the track it'll do best running to about 7200. The same basic engine with a 7448 will power peak at about 5200 rpm yet typically turn the best lap times revving to about 6800.
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Lead Driver
Joined: Nov 2000
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From: Albuquerque
My old dyno 2000 charts show peak HP at 6,000! Manifold only advertises to 5500 but there are a lot of improvement. Guess I'll do the dyno when it cools off a little, 100 degrees here. If the HP chart is still climing at my shift point I'll know what to do.
Cargo Master
Joined: Oct 2020
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Most of those computer dyno programs assume that stuff like the intake manifold is more ideal than in the real world. They assume that stuff like flow and mixture distribution is uniform from cylinder to cylinder and there isn't any weird standing wave or reversion stuff to mess up the cylinder filling.
Cargo Master
Joined: Oct 2020
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Lead Driver
Joined: Nov 2000
Posts: 6,624
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From: Albuquerque
Engine is balanced, polished rod and crank, ARP bolts all around, MSD, Speed Demon 750, Headers, forged pistons at I think 10:1. Total seal rings, roller cam at 216/224 at .050 with .562/.586 lift. I appreciated the input. Just have to wait for cooler days.