Cam question for the group

[RichieRocket]

My current cam is a Comp Cam 212/212. I am looking to increase my potential operating RPMs a bit. I am looking to keep as many parts as possible that are already operating properly. This is the cam that I am considering at this point in time. High Energy 218/212 Hydraulic Roller Cam and Lifter Kit Buick Grand National 231 V6
Attached is the current build sheet. I would like to here from any engine builders out there that can look at the current build sheet and offer some seasoned advice on upgrading just enough to get me a few more RPMs and retain the badazz parts currently installed. Of course the push rods will be different, but I’m not trying to put 20k into an already great build.

 

[TIMINATOR]

What rpm does it nose over?
What rocker ratio?
How much more rpm do you want?
How much boost?
How many miles on the build?
120# on fresh springs prolly ends up at 105 or so after a while, and thats light.
Keep in mind that the backside of the valve at the inside of the seat diameter, equals about 1.7 square inches x boost pressure of say 20 lbs, subtract that from your intake valve seat pressure, and you have only 70 something lbs effective seat pressure.
In actuality its usually not quite that bad. But it is something to think about!
Everyone has a theory! Lets hear more!
TIMINATOR

 

[TIMINATOR]

To get picky, you need to know the inside diameter of the intake seat cut on the head, compute the area, then figure the area of the valve stem (.09 sq. in. with an 11/32 stem) and subtract that from the computed valve area inside the seat and multiply that by the boost pressure, and subtract it from the used, broken in spring pressure.
Blower/turbo motors need more intake seat pressure than N/A motors.
BUT, then again even that ignores intake air, fuel, and alky spray weight and velocity against the entire backside of the valve as it is closing.
TIMINATOR
End of lesson. Let the storm begin!

 

[RichieRocket]

5500 is where I feel like it is futile to keep it to the firewall. If the Rocker info is not on the build sheet, using T&D rollers , take a guess.. I got the car last year so no idea on miles but new springs around 140s definitely are in order to maintain control at 64 to 6500. Plug threads starting to gather oil so I know there is a bit of blow by… time for a refresh for sure. I’m doing well over 30psi on boost but have not yet replaced the 3 bar with a 5 bar so I will just say the blow off valve was cranked all the way down at the Nats. I’m doing a complete refresh and installing new boost control macs and will use XFI for ramps. Switching over to E85 during this time as well. Looking to get 6500 rpm’s just before 1/4 traps. Trans and gearing will of course play their part but I need a cam that is comfortable at that rpm..

 

[TIMINATOR]

To get picky, you need to know the diameter of the intake seat cut on the head, compute the area, then figure the area of the valve stem (.09 sq. in. with an 11/32 stem) and subtract that from the computed valve area inside the seat and multiply that by the boost pressure, and subtract it from the used, broken in spring pressure.
Blower/turbo motors need more intake seat pressure than N/A motors.
BUT, then again even that ignores intake air, fuel, and alky spray weight and velocity against the entire backside of the valve as it is closing
TIMINATOR
End of lesson.

 

[RichieRocket]

They are Champion ported irons but until I start pulling apart to get the refresh done, with Champion ported aluminum’s, I won’t have seat dia.. I am looking for for more generalized info. 212/212 just seems a bit flat up top and the best run to date was a high 9 with a qualifying pass last weekend at the Nats of 10.6.. at 133.5 mph at the traps, would be much better with a trans brake but was foot braking at 2800 rpm’s, not even close to the potential of this build..

 

[TIMINATOR]

But wait! Theres more!
I do more blower motors than turbo motors...
Turbos arent free HP
What is your turbine inlet pressure? Prolly 1.5 times boost or more! Calculate your exhaust pressure against the valve too!
Springs are cheaper and easier to change! Wait for some replies and see what other fast guys are using!
P.S. last LAKE BOAT motor.....
14/71 blown, water/air intercooler, 572" Merlin, Brodix, and notice the n2o nozzles...
TIMINATOR

 

[Turbo6inKY]

5500 is where I feel like it is futile to keep it to the firewall. If the Rocker info is not on the build sheet, using T&D rollers , take a guess.. I got the car last year so no idea on miles but new springs around 140s definitely are in order to maintain control at 64 to 6500. Plug threads starting to gather oil so I know there is a bit of blow by… time for a refresh for sure. I’m doing well over 30psi on boost but have not yet replaced the 3 bar with a 5 bar so I will just say the blow off valve was cranked all the way down at the Nats. I’m doing a complete refresh and installing new boost control macs and will use XFI for ramps. Switching over to E85 during this time as well. Looking to get 6500 rpm’s just before 1/4 traps. Trans and gearing will of course play their part but I need a cam that is comfortable at that rpm..

You're likely not limited by the cam. Sounds like it's hurt.

I have a 212/212 roller with the TA heavy duty stock style shaft mounted stamped rockers and I can slam it against fuel cut at 6500 any time I want, and it isn't nosing over on the way there. And that's on 17-24psi depending on the ethanol content that's in the tank.

 

[RichieRocket]

Can you hold that rpm from 330 to 1/4 ? I know it needs a complete refresh but holding 6500 to any length of time sounds dangerous for my current comfort level..

 

[TIMINATOR]

At that boost level, a solid roller should be a consideration, or at least solid rollers on a hyd rlr shaft. At the very least, adjust the preload down near the bottom of the travel, say a half turn up. Unless you have short travel lifters. Figure out how much longer pushrods you will need to keep the rocker geometry correct. If you have normal travel lifters, some cars will gain a tenth or more lashed from the bottom up. It depends on oil pressure, oiling mods, oil weight, oil temp, rpm, boost, windage tray or not, lifter brand, and lastly phases of the moon.....
It sounds like there is more there.
TIMINATOR

 

[Nigel]

I would be surprised if the stock heads continue to hold power, all else being correct, at that RPM. What kind of quarter times and trap speed are you pulling? What is the rest of the combo?

 

[Pronto]

What exhaust are you running? The spring pressure looks too light. Might want to look at lighter weight springs/keepers.

 

[RichieRocket]

I would be surprised if the stock heads continue to hold power, all else being correct, at that RPM. What kind of quarter times and trap speed are you pulling? What is the rest of the combo?

Stock heads are long gone. Current heads are Ported Champion irons and switching over the Champion aluminums. Best 1/4 was 9.9xx last weekend was 10.6 on a very light 2800 foot brake launch and 133 trap. Going with a trans brake so will be leaving at 3800 to 4200.

 

[RichieRocket]

What exhaust are you running? The spring pressure looks too light. Might want to look at lighter weight springs/keepers.

Replacing springs with 140s during refresh after break in they should be in the 125ish range. Dual 3’ exhaust.

 

[RichieRocket]

I would be surprised if the stock heads continue to hold power, all else being correct, at that RPM. What kind of quarter times and trap speed are you pulling? What is the rest of the combo?

The combo is listed on the build sheet but let me see if I can locate some more details.

 

[Nigel]

Stock heads are long gone. Current heads are Ported Champion irons and switching over the Champion aluminums. Best 1/4 was 9.9xx last weekend was 10.6 on a very light 2800 foot brake launch and 133 trap. Going with a trans brake so will be leaving at 3800 to 4200.

I was referencing the ported stockers (8445s), which is what the champion irons are. But, if you are switching to ported aluminum then that bottle neck is opened up some. 133mph on a 28" tire is 16% slip with stock gearing. Making more power higher up will push that point out, you may find your self trapping at a higher RPM than the target of 6500rpm after a change.

 

[RichieRocket]

Current setup fuel pumps are now the Dual Racetronix rated at just over 700lph. All else is current.

 

[Nigel]

My 2 cents would be freshen the engine, good valve train parts. I am not experienced in high rpm builds so get good stuff set up by the right guy. But If you went to stock gearing, you could keep the trap rpms in the 6000 range, assuming a 6% slip at the trap. Your current converter on first pass looks good for that, but if not consider a converter upgrade Would keep you right in the meat of the current power output.

 

[Mr.Spool]

5500 is where I feel like it is futile to keep it to the firewall. If the Rocker info is not on the build sheet, using T&D rollers , take a guess.. I got the car last year so no idea on miles but new springs around 140s definitely are in order to maintain control at 64 to 6500. Plug threads starting to gather oil so I know there is a bit of blow by… time for a refresh for sure. I’m doing well over 30psi on boost but have not yet replaced the 3 bar with a 5 bar so I will just say the blow off valve was cranked all the way down at the Nats. I’m doing a complete refresh and installing new boost control macs and will use XFI for ramps. Switching over to E85 during this time as well. Looking to get 6500 rpm’s just before 1/4 traps. Trans and gearing will of course play their part but I need a cam that is comfortable at that rpm..

The spring pressure is very important.
I would put more spring on what you have.
Look at converter slip cause you shouldn't need to 6500 to be running 9s on a 3.42 gear car.
Compression test and leak the motor down 1st and look at the ratio of the rockers,they are stamped on the td right on them.
You could also drop gearing to a 3.23 to get more rpm.
The champion iron heads will go alot faster but there is only so much lobe lift you can have so you need to see what rockers are on there if you decide to swap out the camshaft.

 

[Mr.Spool]

If you could list the combo it would be helpful you can pm me if you wish