Cyl Heads-Navarro vs Edelbrock or Offenhauser

[Ol' Ron]

The only way to make Horsepower, is to get more air into the engine. That's why blowers work so good. The cylinder head is actually part of the intake port, when incomes to getting air into the cylinder. and the quest goes on!

[Pete]

Originally Posted by JWL

Actually I was mentioning the book info so Ron could look it up.

The lower unit? Pulling vacuum in the crankcase does little for lower end performance increases when the correct pan is used.

> There is more to it than that.

The reason what is bolted on above the block face matters is because of the additional 3,000+ RPM.

> The efficiency of the lower unit at any rpm would be close to the same no matter if there were no heads on the engine and it was driven by an electric motor or it was running under it's own power. The vacuum reduces pumping losses and helps the rings seal. If you had an electric motor driving it, you would lose the combustion gas helping seal the rings so there would be some loss in efficiency there.

As a matter of fact the engine which showed a reasonably consistent 6 HP improvement was a pretty aggressive 304 with Roller Cam and fabricated tunnel ram intake. Hardly suitable for extended street mileage.

> Roller cam aggressive? NO! Long life, yes.
Tunnel ram, ancient technology. Can be made to run very well on the street.
Tuned properly, that engine would probably be ok on the street.

Here is some more info along these lines.
One of my customers to whom I furnished ALL of the valve train parts and only recommended what engine parts to buy and what to do to the engine, called me yesterday and said it was running in his 34 and made 224 hp at the rear wheels.
This is a 304 with knife edged light weight small diameter Moldex crank, windage tray with scrapers and vacuum pump.
This has 3 250 CFM Strombergs on it with race gas. 404A cam. Titanium lifters and valves. This is the first engine I have been associated with for a long time that is not a dry sump. The vacuum pump thing is why I thought I would mention it. The thread was pretty well hijacked anyway.....LOL

[Ol' Ron]

My question here is?? where did the block get the air to produce this kind of power? I built the 294 short block that produced 235 HP at 4500 rpm. Mild cam and 1.6 chevy intakes and a Magnason blower and only 3.5 lbs boost. We'd like to see the power at 5k but didn't want to blow it up. These big Hp Numbers on normally aspirated fatheads, make me wonder.

[Pete]

Originally Posted by Ol' Ron

My question here is?? where did the block get the air to produce this kind of power? I built the 294 short block that produced 235 HP at 4500 rpm. Mild cam and 1.6 chevy intakes and a Magnason blower and only 3.5 lbs boost. We'd like to see the power at 5k but didn't want to blow it up. These big Hp Numbers on normally aspirated fatheads, make me wonder.

First off, your engine is NOT going to blow up at 5k or even 6K rpm.

For my engines, I have found the flow bench is pretty much a waste of time.
I found out back in the 50's that every time I went bigger on the ports I went faster. Now I just take them out to a .100 minimum wall all the way through.
The exhausts get some welding mods also. When I get done the exhaust ports are 2 inch diameter at the flange. While the valve is only 1.7 dia, Boyle's laws of gas flow say it is better to have the pipe/port get bigger in dia. as it goes out.

[Ol' Ron]

Pete
That is very impressive. I moved my exhaust ports to straighten them out. The block is on the cover of my book and also in the book. I flow them ant they only improved by 4%. Probably good in a Biville engine. But I don't think it's necessary with other mods to the port exits. I also realize tha the exhaust is important to make HP. But we still have to get the air into the block and the blower does it, where Mother nature can't I must admit that you gave me the idea for my ports. Having worked on aircraft, and a student of John Rontz air flow. THe math is far beyond my understanding. But I think the guys that designed the LS engines read his book. What I'm doing might not work, but it's a good reason to get up in the morning.

[Lawrie]

Sponsored Links (Register now to hide all advertisements)

You are right about the blower,our old hilborn injected engine in the dragster only went about 115 mph, built the new engine with a 471blower and best so far is 142 mph.
Lawrie

[40 Deluxe]

Originally Posted by Pete

I have never done an engine that small but the same principles should apply as a big one except not as great. You may have to settle for a max of 11 to 1. I can get 14 to 1 on a 321 inch engine.
First, get a set of flat top gas ported 2 ring pistons with narrow low tension rings that come to the deck. Set final piston to head clearance to .035.

Fill the dome on the heads so they will finish flat in that area.
Measure the transfer area at it's max. depth. Fill that part so it will finish about 20% less than original. If you can fill the valve area any to get your .040 clearance, do that.
You can get the job done ok with brass and it will work but if it was me, I would TIG weld it with ER70 rod with preheat, peening and slow cool.

If you put a vacuum pump on that engine and get 15 inches of Hg. you will gain about 20 hp. That will require some minor sealing mods but I can walk you through that if need be.

Just curious: It seems to me that a .035" piston to head clearance would give nearly the same compression whether flat top pistons or the original dome style. Where is all that extra compression to be found? Thanks!

[Pete]

Originally Posted by Ol' Ron

Pete
That is very impressive. I moved my exhaust ports to straighten them out. The block is on the cover of my book and also in the book. I flow them ant they only improved by 4%. Probably good in a Biville engine. But I don't think it's necessary with other mods to the port exits. I also realize tha the exhaust is important to make HP. But we still have to get the air into the block and the blower does it, where Mother nature can't I must admit that you gave me the idea for my ports. Having worked on aircraft, and a student of John Rontz air flow. THe math is far beyond my understanding. But I think the guys that designed the LS engines read his book. What I'm doing might not work, but it's a good reason to get up in the morning.

Many people are reluctant to spend a lot of time on porting a street engine when that is a very cheap way to make hp gain.
If you are building your own engine, your time is not worth much if you consider your car a hobby. Usually the nitty gritty details individually will only gain a very small percentage but a lot of these added up will make an increase worth going for.
Porting with an ultrasonic gauge takes a HUGE amount of time and patience.
The cost? 300 hours of your time, electricity for lights/fans and to run the compressor, a couple of die grinders and a handful of burrs and stones.
There is the also the nominal cost of a BIG sign hanging on your shop wall saying, " BIGGER IS BETTER".

[Pete]

Originally Posted by 40 Deluxe

Just curious: It seems to me that a .035" piston to head clearance would give nearly the same compression whether flat top pistons or the original dome style. Where is all that extra compression to be found? Thanks!

A flat plane has less area than any spherical surface the same diameter.
The flame front has a shorter distance to travel across the piston also.

The rest of it is in the transfer area.

[Ol' Ron]

Yes Pete, been there done that. Often wondered how well it worked, I had a special system for the street engines. When I was flow testing with the homemade flow bench I found out where the best place to start porting was. By spending about 10/15 min in a port I could improve flow about 10%. Not sure how much it helped, but it looked good.. Now filling the water jacket around the port with liquid steel is a bitch.

[prpmmp]

Pete and Ron keep it going!! This is entertainment at its best!! Don't understand it all but I,m enjoying the show!!!! Pete

[Ziggster]

I just watched an older vid from PowerNation TV where they did up a flathead. It was bored and stroked to 304 cu in, with 3/4 race cam, triple carbs, ported with larger Chevy valves, etc. Made a whopping 156 Hp at the crank. Torque was a little more impressive at 265 lb-ft.

https://www.powernationtv.com/episod...tty-3-deuce-v8

[Pete]

Originally Posted by Ziggster

I just watched an older vid from PowerNation TV where they did up a flathead. It was bored and stroked to 304 cu in, with 3/4 race cam, triple carbs, ported with larger Chevy valves, etc. Made a whopping 156 Hp at the crank. Torque was a little more impressive at 265 lb-ft.

https://www.powernationtv.com/episod...tty-3-deuce-v8

That combination makes one of the best ECONO street engines you can have.

[Tim Ayers]

Originally Posted by Pete

First off, your engine is NOT going to blow up at 5k or even 6K rpm.

For my engines, I have found the flow bench is pretty much a waste of time.
I found out back in the 50's that every time I went bigger on the ports I went faster. Now I just take them out to a .100 minimum wall all the way through.
The exhausts get some welding mods also. When I get done the exhaust ports are 2 inch diameter at the flange. While the valve is only 1.7 dia, Boyle's laws of gas flow say it is better to have the pipe/port get bigger in dia. as it goes out.

That looks awesome. Pete, what the deal with the re-routed cooling? (I'm assuming that's what that tube is going along the outside of the block).

[Pete]

Originally Posted by Tim Ayers

That looks awesome. Pete, what the deal with the re-routed cooling? (I'm assuming that's what that tube is going along the outside of the block).

Yes, it is a water manifold to equally take water out of the bottom of the cylinders.

[Tim Ayers]

Originally Posted by Pete

Yes, it is a water manifold to equally take water out of the bottom of the cylinders.

Electric pump?

[Pete]

Originally Posted by Tim Ayers

Electric pump?

On the circle track engines the water pump is one section of the dry sump pump.

On the LSR engine I am on now it will be electric.

[Ol' Ron]

That was a popular water system on th 60 hp midget blocks. eliminated the fan belt, Never saw that on the big blocks tho. That another good idea Pete. Learn sumpin every day!!

[Pete]

Originally Posted by Ol' Ron

That was a popular water system on th 60 hp midget blocks. eliminated the fan belt, Never saw that on the big blocks tho. That another good idea Pete. Learn sumpin every day!!

Yes, we did a bunch of them on the 60's. That's a Martas pump.

Here are pics of one on an 8ba. The red belt goes down to the power steering/dry sump pump.

[Ol' Ron]

Combustion chamber shape?? Might as well get this one started. Back in the 80's when I was doing all this experimenting, I made up a wooden cylinder head and carved in a bunch of chambers after measuring most stock and aftermarket chambers. I was looking for the best flow compared to CR. I do have some pics of this somewhere. The best one was a piston with a 7 degree top and the head with an 8 deg angle. This pop up piston forced the AF into the valve area. It also allow for a very hi CR with excellent flow. I made up a piston shape with Bondo and sent it to EGGE and asked them if they could make a piston for me with enough material on it for me to machine the top. The cost was 600 dollars, which was far beyond my means.
Fast forward to 2003 and I was at Bivlle with JWL and the flathead powered Hudson. I was shocked the pistons in it. Just like the ones I had sent to EGGE and the Heads were made by Navarro. Interesting, but I'm still not sure this is the right shape. But, I still think the spark plug should be in the center of the transfer area . This creats a shorted flame front and allows for a power tip plug. Be interested in any comments, food for thought.