New Converter, Different Shift Points?

[1320racer]

Originally Posted by S/ST 3040

It's really not set up to be a bracket car either, as 8500-8700 RPM, lap after lap at doesn't lend itself to the typical season. It's just my attempt at ET chasing with an engine I'm familiar with.

so you're a career test/tuner, what a surprise.

Originally Posted by S/ST 3040

I can't imagine my car coming close to it's current performance with a camshaft 40º smaller.

your combo with the right cam that without question needs far less duration at .050 than your current 280+, will accelerate your car quicker and faster than it's current performance, with the right converter of course and you'll do it turning less than 8000 RPM!

FYI, all your ET is made in the first 330 feet and 60 foot is EVERYTHING!

[pfordamx]

Have to agree that conventional wisdom would say a 280@ .050 cam is going to want at least 11 or 12.1.

[1320racer]

wrong, MORE!

[pfordamx]

Originally Posted by 1320racer

wrong, MORE!

ok enlighten me so the compression isn't whats wrong with the cam i know theres alot too picking a cam displacement, compression, cylinder head flow, velocity exhuast port vs intake flow low lift vs high lift and whole list more but a general statement a that a bigger cam will work better with more compression i don't see as being completely wrong.

[pfordamx]

Originally Posted by Mike Pearson

Those numbers are not real shabby for something that you built yourself. Non of us started out setting the world on fire. Just keep asking questions and talk to the educated guys about your combo, Talk to the cam companies about a good cam for your combo. Also stick with the better converter companies for a converter that will optimize what you have. Best of luck with your ride and the most important thing is you have fun with it.

curious he mentioned ati is ati not one of the better converter companies?

[Mike Pearson]

Originally Posted by pfordamx

curious he mentioned ati is ati not one of the better converter companies?

In my opinion ATI is the best. I have had an ATI converter in my car for all of my career with an auto. There are several others that are good as well.

[Adger Smith]

I have been dealing with customers for over 45 years that have the same problem you do. I call it testosterone poisoning. Some how the camshaft and cylinder heads are where this disease is usually found. The bigger is better disease. What you have is very little dynamic compression with the low static and the high cam duration @ 50. An engine does not operate on just static compression. the closing point of the intake valve vs the static and other engine parameters makes the dynamic. For instance I have a SS Modified engine that has 15.8 static and a 282 @ 50 cam shaft. Where I have the cam installed it pumps 225 lbs on the 4 th hit. It makes 2.5 hp per cu in. What we are all trying to tell you is the engine may be making hp at high RPM it is not making TQ with that long @ 50 cam and the low (relatively) static compression. That is why it likes the slipping converter. It take cylinder pressure to make power. In dyno terms it is BMEP and it usually happens around peak TQ. The trick to making real power is to extend/expand the RPM band of peak BMEP. To do that you need air and fuel to make the cylinder hotter. It is all about Heat and pressure. You need more pressure...Talk to your favorite cam guy, and no offense, not the minimum wage Cam Help salesman. The guy that knows what a cam does. don't start the conversation out by telling him the size cam you want. You already have the results of that. OK, you have my .02 I'm finished. It is late and my pillow needs some head...

[1320racer]

Originally Posted by S/ST 3040

The engine is +.060" 340 w/9.24:1 compression, OEM 596 castings w/1.88" IN valve, roller cam, Victor 340 manifold and Holley 950 carburetor.

so based on this, I stated this in post #6 without knowing anything about his cam...

Originally Posted by 1320racer

you have an engine combo that maybe makes 500+HP and 400+ ft/lbs. torque at probably around 5000 RPM.

knowing that anybody today can put together a 1.5HP/cu.in bracket type engine with out of the box parts. Well I was wrong. The OP has somehow manage to throw this engine together using these junk heads that don't flow 200cfm and the way wrong cam he chose resulting in an engine that only makes about 1 HP/cu.in. not to mention that the 8700 RPM he's buzzing this grenade to is ~ 2500 RPM past peak HP!

As I stated previously, his current cam is about 40 degrees too big at .050 and we have no clue to how much lift or the LSA. Installing the right cam with ~40 degrees less duration at .050 will make ~ 100 more ft./lbs torque at peak and ~ 60 more HP at peak and peak RPM will be lowered by ~300. This engine will require a shift point of ~ 6200, a converter that flashes to ~ 5000 RPM and be geared to trap ~ 6800 RPM. More importantly it will accelerate his 2600 lb. bucket of bolts quicker and faster than it's current performance!

[S/ST 3040]

Originally Posted by Adger Smith

I have been dealing with customers for over 45 years that have the same problem you do. I call it testosterone poisoning. Some how the camshaft and cylinder heads are where this disease is usually found. The bigger is better disease. What you have is very little dynamic compression with the low static and the high cam duration @ 50. An engine does not operate on just static compression. the closing point of the intake valve vs the static and other engine parameters makes the dynamic. For instance I have a SS Modified engine that has 15.8 static and a 282 @ 50 cam shaft. Where I have the cam installed it pumps 225 lbs on the 4 th hit. It makes 2.5 hp per cu in. What we are all trying to tell you is the engine may be making hp at high RPM it is not making TQ with that long @ 50 cam and the low (relatively) static compression. That is why it likes the slipping converter. It take cylinder pressure to make power. In dyno terms it is BMEP and it usually happens around peak TQ. The trick to making real power is to extend/expand the RPM band of peak BMEP. To do that you need air and fuel to make the cylinder hotter. It is all about Heat and pressure. You need more pressure...Talk to your favorite cam guy, and no offense, not the minimum wage Cam Help salesman. The guy that knows what a cam does. don't start the conversation out by telling him the size cam you want. You already have the results of that. OK, you have my .02 I'm finished. It is late and my pillow needs some head...

I'm listening. Thanks for the input.


I will definitely look into experimenting with different cams. It sounds like it would pay to find a shop that has a dyno that will accommodate something besides a SBC. I've had a few members contact me with some helpful information and I appreciate that.

[S/ST 3040]

Originally Posted by 1320racer

so based on this, I stated this in post #6 without knowing anything about his cam...



knowing that anybody today can put together a 1.5HP/cu.in bracket type engine with out of the box parts. Well I was wrong. The OP has somehow manage to throw this engine together using these junk heads that don't flow 200cfm and the way wrong cam he chose resulting in an engine that only makes about 1 HP/cu.in. not to mention that the 8700 RPM he's buzzing this grenade to is ~ 2500 RPM past peak HP!

As I stated previously, his current cam is about 40 degrees too big at .050 and we have no clue to how much lift or the LSA. Installing the right cam with ~40 degrees less duration at .050 will make ~ 100 more ft./lbs torque at peak and ~ 60 more HP at peak and peak RPM will be lowered by ~300. This engine will require a shift point of ~ 6200, a converter that flashes to ~ 5000 RPM and be geared to trap ~ 6800 RPM. More importantly it will accelerate his 2600 lb. bucket of bolts quicker and faster than it's current performance!

I understand cylinder pressure and what components affect it but, I can't figure volumetric efficiency or dynamic compression. I understand what you are trying to tell me but, I do know this..........a N/A 340 will not run better, if it's geared to cross the finish line at 6800 RPM. That would be like switching to a 4.30 gear with my current 31.2" tire just to match 135 MPH. No Way. We have turned the post from shift points to torque converters to camshafts........and I'm completely OK with that. I'm learning! I'm even looking into a different car to try to build a super stocker.





Just guessing, I'm going to say peak HP is about 7000 RPM and Peak TQ probably 5400 RPM.