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HPR 468 peaking to low.

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Old 07-12-2021, 02:08 PM
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Originally Posted by JRFed
Just from what we have seen I really believe you have a valvetrain issue. Those are pretty heavy rockers IMO and do you have weight on those intake valves? Or part number? I can do some math on my end.
No man I don't, the heads came from Tony Mamo. I actually wanted the TSP roller tip rockers which I've used in the past with great success, but at the time TSP didn't haven't them and didn't know when they would because of covid-19.
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Old 07-12-2021, 05:09 PM
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Originally Posted by JRFed
Just from what we have seen I really believe you have a valvetrain issue. Those are pretty heavy rockers IMO and do you have weight on those intake valves? Or part number? I can do some math on my end.
The YT rockers that he’s using are 10.5 grams over the nose heavier than an OEM steel rocker. I’ve done the math. 10.5 grams is a lot of weight, don’t get me wrong, but not substantial at 6500-7000 rpm. 8000+ rpm is a different story. Tony sets the springs up to handle the rockers. I have the same setup, and my limiter is set to 7800 and I’ve been up over 8k many times without issue. The hollow intake valves are 3 grams lighter than the exhaust valves.
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Old 07-12-2021, 05:16 PM
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Originally Posted by BigDaddy97
Is there a 108/112 dbc throttlebody anywhere that you know of. All I can find is dbw.
Sending you a DM
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Old 07-12-2021, 05:51 PM
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Originally Posted by DualQuadDave
Sending you a DM
Replied Dave
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Old 07-12-2021, 07:04 PM
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Originally Posted by spanks13
The cam seems pretty damn small to me for a drag race 468 to expect more than 6500rpm. Comp spec'ed hydraulic roller was well over 700 lift for a street 468, and I would wager more duration and overlap than your cam too. .74x lift, 26x/27x duration on a 113 +4.
That was my first thought. I bet the intake he has can easy peak at over 7k with a bigger cam
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Old 07-12-2021, 08:16 PM
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Originally Posted by JRFed
Ti valves or stainless steel valves on both intake and exhaust? I think I found your issue.
Oh boy here we go
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Old 07-12-2021, 08:43 PM
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Originally Posted by ramairws6
Oh boy here we go
It's all ball bearings nowadays.
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Old 07-12-2021, 10:06 PM
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Erik's Still got a Sense of humor....


CID and 4500....Old Conversation on YB about 468 thru 528 inch combinations and What guys are or where using.... A 105-112mm 🤣😂 and the Air is coming from the Front....Bad idea? Engine love it's Air Stream line = Air from the Top Carb style.

Run it & get a Baseline...😂🤣 a few said this.


You can Control a Heavier Valve with a good Spring so As Long as the Rocker it Self is Stable....
I know of Guys With Studs and Girdles running 8500 it may Not be the Best but So as Long as it's

Sturdy..

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Old 07-12-2021, 10:39 PM
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Originally Posted by Launch
That was my first thought. I bet the intake he has can easy peak at over 7k with a bigger cam
Spanks or Launch do the Math with the Heads = CSA + the Engine Size then the Cam...

Oh boy! Look at that!




I've Been Told by a Guy about this Combination .....
And it's CSA and MCSA
🤫
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Old 07-13-2021, 12:31 AM
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Originally Posted by JRFed
Just from what we have seen I really believe you have a valvetrain issue. Those are pretty heavy rockers IMO and do you have weight on those intake valves? Or part number? I can do some math on my end.
Heavy Rocker arms...🤣😂 Vs what I said Earlier...
A Great Shaft mounted Rocker arm Should be a Minimum Mandatory with Any high End build.


https://www.efi101.com/valve-train-t...tem-stiffness/

Last edited by Corona; 07-13-2021 at 12:36 AM.
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Old 07-13-2021, 07:50 AM
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A 102 TB actually flows closer to 1400 CFM at 20" of water (or 1.5" of mercury....both representing the same pressure drop and the "standard" most carbs and throttle bodies are flowed at)

On paper a 102 straight pipe with a radiused entry would flow 1550 ish CFM but throw the blade and shaft in there (a small obstruction) and the little bit of curvature built into the bore housing to help give it some drivability and your looking around 1400 CFM

Some of my ported 90mm TB's flow 1200 CFM and the difference looking down the mouth of both of them is quite substantial.

All that said with EFI engines more air usually makes a little more power even though on paper the engine demand for airflow would tell you it wouldn't be needed.

Looking at the KPA reading from the dyno pulls is the best way to determine the type of restriction there is on the inlet side of things and even then the TB only represents part of that equation.

Not sure why numbers and a dyno sheet isn't being shared here with the community as there is info to be gleaned from the shape of both curves (power and torque) but I suspect this engine will run pretty strong and will still show the best track results shifting north of 7000 RPM

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Old 07-13-2021, 11:15 AM
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Originally Posted by BigDaddy97
Hi Dan, I actually have 4.10s in it now but have 4.30s in reserve if need be.
I have 4.30 on mine. They were great with the 346, but with the 440, they're almost too much gear. I think if you were to go to 4.30, you should also go to a taller tire.
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Old 07-13-2021, 12:03 PM
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Originally Posted by DualQuadDave
They do make bigger throttle bodies. May as well just slap one on and try it. My guess is you are correct, it's a choke of some point. Could be valvetrain going nuts, but would probably show it on the dyno different. When you are at the level you are at, change one thing at a time and test. Data is you friend.
I'm sure you've seen this before, but with your peak at 6500 and carrying to 7K with only 10hp drop, I would not generally think valve train. Usually when I encounter valve train issues, i'll see one of two scenarios. Either the graph gets really jaggedy, or it falls off a cliff, as in dropping 100 hp from 6700 to 7000 rpm:




But if your dyno basically looks like this, I would think the valvetrain was doing fine:


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Old 07-13-2021, 12:32 PM
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Originally Posted by Tony @ Mamo Motorsports
A 102 TB actually flows closer to 1400 CFM at 20" of water (or 1.5" of mercury....both representing the same pressure drop and the "standard" most carbs and throttle bodies are flowed at)

On paper a 102 straight pipe with a radiused entry would flow 1550 ish CFM but throw the blade and shaft in there (a small obstruction) and the little bit of curvature built into the bore housing to help give it some drivability and your looking around 1400 CFM

Some of my ported 90mm TB's flow 1200 CFM and the difference looking down the mouth of both of them is quite substantial.

All that said with EFI engines more air usually makes a little more power even though on paper the engine demand for airflow would tell you it wouldn't be needed.

Looking at the KPA reading from the dyno pulls is the best way to determine the type of restriction there is on the inlet side of things and even then the TB only represents part of that equation.

Not sure why numbers and a dyno sheet isn't being shared here with the community as there is info to be gleaned from the shape of both curves (power and torque) but I suspect this engine will run pretty strong and will still show the best track results shifting north of 7000 RPM

-Tony
If I had an engine dyno around my area I would certainly have shared my dyno sheet and numbers. On the other hand a chassis dyno is way to easily manipulated in my opinion. If the numbers don't suit a person, you can go across town to another one that "reads" higher and get bigger numbers or I could replace my heavy 29.5 drag radials with lighter 28" bias ply slicks and get a bigger number. A guy with the same engine as me and a manual transmission is gonna dyno a lot more than me because I'm running a powerglide and a 8" 6000 stall even though I'm most likely faster at the track. For me, a chassis dyno is just a tool to see where my peaks are and to get a baseline so that I can see if there is a gain or loss on power if I were to change a cam, throttlebody, intake, etc. The numbers themselves mean nothing to me.
There is nothing special to see on my dyno sheet, it ramps up about 6k (stall speed), hits max hp at about 6500, and drops only about 10hp from 6500 to 7k, no funny looking spikes or dips. You could almost lay a framing square on my power curve. It makes more power and torque than my old 447 and that's good enough for me. Would just like to shift the peak up some if I can.
Simply put track numbers are the only numbers that matter to me and I will happily post those numbers once I have them.
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Old 07-13-2021, 12:54 PM
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No offense, but your chasing 500rpm if you spend x amount of money to gain rpm you may then have to spin the motor 7500rpm+ You are a seasoned veteran at the track. Go run it and see where you are and dial her in a bit. I think you will meet your goal and spend your hot rod money on a nice vacation this winter
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Old 07-13-2021, 01:09 PM
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Originally Posted by lazerlemonta
No offense, but your chasing 500rpm if you spend x amount of money to gain rpm you may then have to spin the motor 7500rpm+ You are a seasoned veteran at the track. Go run it and see where you are and dial her in a bit. I think you will meet your goal and spend your hot rod money on a nice vacation this winter
Yes sir, I haven't ordered anything yet, just collecting information for possible winter changes. I plan to run it the rest of the season as it is.

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Old 07-13-2021, 02:35 PM
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Originally Posted by BigDaddy97
If I had an engine dyno around my area I would certainly have shared my dyno sheet and numbers. On the other hand a chassis dyno is way to easily manipulated in my opinion. If the numbers don't suit a person, you can go across town to another one that "reads" higher and get bigger numbers or I could replace my heavy 29.5 drag radials with lighter 28" bias ply slicks and get a bigger number. A guy with the same engine as me and a manual transmission is gonna dyno a lot more than me because I'm running a powerglide and a 8" 6000 stall even though I'm most likely faster at the track. For me, a chassis dyno is just a tool to see where my peaks are and to get a baseline so that I can see if there is a gain or loss on power if I were to change a cam, throttlebody, intake, etc. The numbers themselves mean nothing to me.
There is nothing special to see on my dyno sheet, it ramps up about 6k (stall speed), hits max hp at about 6500, and drops only about 10hp from 6500 to 7k, no funny looking spikes or dips. You could almost lay a framing square on my power curve. It makes more power and torque than my old 447 and that's good enough for me. Would just like to shift the peak up some if I can.
Simply put track numbers are the only numbers that matter to me and I will happily post those numbers once I have them.
i would put a vacuum gauge on it and run it. If it's pulling more 1hg at the top end, then it's def the intake. Your problem could also be the converter. Have seen it before in nitrous cars. They'll make power to a point then slip. Very hard to diagnois.
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Old 07-13-2021, 05:33 PM
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Just tossing around ideas here and investigating all options: I read through fnbadazz06 468 build post and saw that he showed a decent gain and peak rpm change by adding a 112 throttlebody to his carbon 105 intake using an adapter. I was on the Visner site and they sell a big oval port throttlebody and a oval port to 105 mm adapter. Anyone here used that Visner oval throttlebody? Again just gathering information
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Old 07-13-2021, 06:13 PM
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What intake Do you Have Right now and Using...
​​​​​​
We gonna Keep it Simple as I like You.
What type of TB is Wanted?
DBC or DBW?




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Old 07-13-2021, 06:38 PM
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Originally Posted by Corona
What intake Do you Have Right now and Using...
​​​​​​
We gonna Keep it Simple as I like You.
What type of TB is Wanted?
DBC or DBW?
Carbon pst using a dbc throttlebody
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