BBC thoughts

[F-BIRD'88]

There is no doubt that the dyno does show you the gains

but this is true and critical...... you also need to BRING THE STUFF TO THE DYNO SESSION(S) like 2+ sets of headers CAMS, carbs etc to test with..

This is how you see gains. You have to try stuff.

Thats what dyno testing is for. May take you 2 days ....
But you will get results.
A bud spent over a week on the dyno , on a 355 sbc.
But he ended up with BIG POWER GAINS.

[F-BIRD'88]

As you can see from Chris's posts you don't need excessive compression ratio to make great power on a street motor
that runs real pump gas. 10:1 ----10.50:1 is plenty.

[F-BIRD'88]

Question: When you go racing/testing what race track are you going to?

[GARY C]

Yes plan #1 seems most logical and affordable. Now i've started thinking about cams again. As i stated in my other post, I sold my Straub cam and this Lunati is on its 3rd engine and is in roughish shape. Plus i don't feel its optimal. Its was just local and cheap so i tried it. I've been studying my David Vizard book and this is the cam i come up with according to his theory loosely scienced out by me for 555 cubes at 11 CR with a 2.3 intake valve.

ERSON E129894 302 / 306 274/278 @ .050 .740/.740 108 LSA

Chris Straub told me that my AFR 335 CNC heads require less difference in duration between the intake and exhaust than other heads so thats the reasoning for that. DV's book would put me at around a 104 - 105 LSA but thats impossible to find without going custom. I used 93 for overlap based on DV's graph and 106 for LSA to do the math to come up with 302 / 306 duration and used 4 for the difference to do the calculation to figure the duration. The overlap graph wants me to have 12.5 + CR but thats not happening either. I used 555 cubes and 7250 rpm to arrive at the 93 overlap. after all the math the Erson cam above seems to come closest to what should work. I'm sure everybody will have a different idea on this but i'm willing to hear everyone's idea. I've been wrong before.
Brian

If I read that correctly, after studying DV's book you misused his info to choose a cam that you your self admits is wrong for your application?

The cam does not make your engine a 7250 RPM engine... It is designed for an engine that is properly built for 7250 rpm...(Compression, head and intake size!) It is not a matter of will it turn the rpm but is it making power at that rpm?

[prairiehotrodder]

SIR - saskatchewan International raceway.

1500 approx. feet if thats what you want to know.

[F-BIRD'88]

Agree...He is misusing the charts , formulas and information of DV's whole method.
Picking only the parts he likes... "feels" taking defining terms out of CONTEXT

and then ignoring the calculated result especially LSA and THEN picking a off the shelf cam
that is not close...

[prairiehotrodder]

Yes plan #1 seems most logical and affordable. Now i've started thinking about cams again. As i stated in my other post, I sold my Straub cam and this Lunati is on its 3rd engine and is in roughish shape. Plus i don't feel its optimal. Its was just local and cheap so i tried it. I've been studying my David Vizard book and this is the cam i come up with according to his theory loosely scienced out by me for 555 cubes at 11 CR with a 2.3 intake valve.

ERSON E129894 302 / 306 274/278 @ .050 .740/.740 108 LSA

Chris Straub told me that my AFR 335 CNC heads require less difference in duration between the intake and exhaust than other heads so thats the reasoning for that. DV's book would put me at around a 104 - 105 LSA but thats impossible to find without going custom. I used 93 for overlap based on DV's graph and 106 for LSA to do the math to come up with 302 / 306 duration and used 4 for the difference to do the calculation to figure the duration. The overlap graph wants me to have 12.5 + CR but thats not happening either. I used 555 cubes and 7250 rpm to arrive at the 93 overlap. after all the math the Erson cam above seems to come closest to what should work. I'm sure everybody will have a different idea on this but i'm willing to hear everyone's idea. I've been wrong before.
Brian

If I read that correctly, after studying DV's book you misused his info to choose a cam that you your self admits is wrong for your application?

The cam does not make your engine a 7250 RPM engine... It is designed for an engine that is properly built for 7250 rpm...(Compression, head and intake size!) It is not a matter of will it turn the rpm but is it making power at that rpm?

I used the formula 's in DV's book which got me in the ball park plus what i've learned from the 2 cams i've allready run, plus what i've learned from talking to Chris to come up with the Erson cam above. For a real DV cam recomend i would need to pay $100 and all my flow numbers put into his program. Since i'm just in the 'kicking around idea stage" i don't feel like paying the $100 and thought i'd take a stab at it myself. I haven't bought anything yet and i'm not sure i am willing to fork out money unless i know cam specs ahead of time. I allready had an incident that took 2 months off my life over a secret cam. Many pro cam grinders are fully willing to tell you up front what cam i should buy.

[F-BIRD'88]

https://airdensityonline.com/track-resu ... l_Raceway/


Here is the weather data for SIS today.
This the real air you have to work with.... It is "uncorrected"
You make "uncorrected horsepower"

This is actually a "good day" for that track. Most days there are not as good air.

So... when looking at someones dyno sheet you need to convert their "corrected power"
printout to your uncorrected world. If the sheet shows 800hp you need to DE-correct it to your track operating condition to see what that will do for you.


Your air is always LESS dense than say mine .
your air is typicaly a bit cooler than mine too sometimes a lot cooler.

[F-BIRD'88]

What did you learn from the 2 cams? They both ran the same.

Here is what I learned from that. The 2 cams ran the same.
So... The 2 cams are either both "optimum" or they are both NOT 'optimum" cams.

Or the cam is NOT THE PROBLEM.
Same with the headers....The 2 headers ran the same..
The headers are not the problem.

The thing that is limiting the engine /car performance is limiting that ENOUGH
so that changing the cam and changing the headers MADE NO DIFFERENCE.
Find the thing that is the big limiting factor.

I think it is the carb and intake manifold. You bought both used because someone else wanted to sell these. Because they did not work that great for them either.

The car needs more gear and you need to move that Lunati cam and test lash too.
But get another carb and intake too to test...
There is no reason to rebuild that motor, it is NOT loosing performance. Nothing indicates it is worn out.

I highly recomend that that other intake be a tunnel ram.
And you will want to rev the motor higher to get the best from that big cam and a tunnel ram.
The higher you gear that car with the 2 speed PG trans the better it will work for you.
When you are racing in thin air as you are, you need to do every thing POSSIBLE and practical to make the engine breathe DEEP. A tunnel ram and 2 big carbs does that.
2 x carbs are not twice the trouble.

[F-BIRD'88]

If the DV cam pick formula method wants a cam with a tight LSA it also wants a lower intake C/L ( smaller number) so if you don;t got that cam on hand then you need to match your cam up as close as possible. You can do that for the Intake side of the equation by MOVING the cam.
You need to advance your 110LSA cam.
Then you can correct the ex side of that cam to better match DV's cam by adjusting the valve lash of the exhaust side OR BOTH. This will make your cam more like his cam.

that big cam in a 10:1cr motor needs to be "advanced"... maybe a LOT.
Especially in a Under geared car... and in thin air too.
Advance it a lot like to 102deg intake C/L.
it really wants 14:1cr..it will scream with a 14:1cr.
You don't have 14:1cr... You got 10:1 so advance the cam..
This will also make the intake side of the cam a lot like DV's cam.
The car will either respond or it won't. Even if it slows the car IT TELLS YOU SOMETHING.
I bet it will improve the car performance. I bet that that + 4.56 gears will do a HELL of a lot.

The best time of year for track testing is coming up.

[F-BIRD'88]

What is the DV method predicted camshaft for the current motor?

[prairiehotrodder]

hmmmm..............

The carb was brand new straight from QFT. The intake was used and has a used 1" HVH super sucker on it. I bought an electric water pump that i will install in the next day or two. I'll advance the cam when i do that job and see if it likes it. I think its currently at 108 ICL.

I know from when i originally degreed the cam that lining up the dots puts it at 103. Its currently at 108 and the R4 position on the crank gear.

[F-BIRD'88]

Question: If both the Lunati and the Straub cams ran the same and the lunati cam is showing wear,, why would you sell the Straub cam?
i am missing the logic here...

[GARY C]

Yes plan #1 seems most logical and affordable. Now i've started thinking about cams again. As i stated in my other post, I sold my Straub cam and this Lunati is on its 3rd engine and is in roughish shape. Plus i don't feel its optimal. Its was just local and cheap so i tried it. I've been studying my David Vizard book and this is the cam i come up with according to his theory loosely scienced out by me for 555 cubes at 11 CR with a 2.3 intake valve.

ERSON E129894 302 / 306 274/278 @ .050 .740/.740 108 LSA

Chris Straub told me that my AFR 335 CNC heads require less difference in duration between the intake and exhaust than other heads so thats the reasoning for that. DV's book would put me at around a 104 - 105 LSA but thats impossible to find without going custom. I used 93 for overlap based on DV's graph and 106 for LSA to do the math to come up with 302 / 306 duration and used 4 for the difference to do the calculation to figure the duration. The overlap graph wants me to have 12.5 + CR but thats not happening either. I used 555 cubes and 7250 rpm to arrive at the 93 overlap. after all the math the Erson cam above seems to come closest to what should work. I'm sure everybody will have a different idea on this but i'm willing to hear everyone's idea. I've been wrong before.
Brian

If I read that correctly, after studying DV's book you misused his info to choose a cam that you your self admits is wrong for your application?

The cam does not make your engine a 7250 RPM engine... It is designed for an engine that is properly built for 7250 rpm...(Compression, head and intake size!) It is not a matter of will it turn the rpm but is it making power at that rpm?

I used the formula 's in DV's book which got me in the ball park plus what i've learned from the 2 cams i've allready run, plus what i've learned from talking to Chris to come up with the Erson cam above. For a real DV cam recomend i would need to pay $100 and all my flow numbers put into his program. Since i'm just in the 'kicking around idea stage" i don't feel like paying the $100 and thought i'd take a stab at it myself. I haven't bought anything yet and i'm not sure i am willing to fork out money unless i know cam specs ahead of time. I allready had an incident that took 2 months off my life over a secret cam. Many pro cam grinders are fully willing to tell you up front what cam i should buy.

I am not saying you should run a Vizard cam, I am just saying if your going to use his method you will be better off doing it as he intended.

[prairiehotrodder]

Question: If both the Lunati and the Straub cams ran the same and the lunati cam is showing wear,, why would you sell the Straub cam?
i am missing the logic here...

The Lunati cam is in now, it had a little better MPH. Got good money for the Straub cam and i want to move forward. I would happily buy another Straub cam but not the same one. If not now, one day i will up the CR and the cubes a little and then i WILL want a new cam. If my motor comes apart the Lunati cam Will be on racing junk. I have bought 2 cams and lifters from Chris and have been happy with it all. But i just want to keep going faster and setting new goals for myself.