Does Running open header or lakester style header hurt motor?

[Logan]

I plan on starting on my speedster in the next couple weeks. i have a lot of the parts that i need, but one thing i have yet to decide on is the exhaust. I've been talking to the guys at work and we all agree a speedster needs to be loud, at least louder than a stock model a. After discussion, we couldnt decide if it would be a bad idea or not to run an open style header, or a lakester style header. One guy said a while back when he was racing mustangs, the exhaust shop told him not to run his cut outs open for long periods of time because it could hurt the valves. So my question is, to all you engine wizards, would it hurt a motor to run it with an open header (tube header) with a turn down pipe or a lakester/zoomie style header?

I plan on driving the car on a semi-regular basis, but i wont be running it really hard.

[BILL WILLIAMSON]

Dog says go for it, no harm, he also said sumthin' about a ticket to sumpthin'???????????? Bill W.

[Rowdy]

As long as the pipes are long enough to prevent cool air from rushing in rigtht after you shut it off there should be no problems. Too short of a pipe and cool air contacting hot exhaust valves could cause warpage. Some of the home made farm equipment had no more than a 16" pipe out of the manifold and no problems with warped valves, so it does not take much. Rod

[40 Deluxe]

Has this cool air/hot exhaust valve warping theory been proven for a fact, or is it just another legend/myth??

[dave in australia]

Originally Posted by 40 Deluxe

Has this cool air/hot exhaust valve warping theory been proven for a fact, or is it just another legend/myth??

Just another myth. Aussie V8supercars, NASCARs, F1's and other non-blown racing formulas run with open headers for hours on end and don't damage their exhaust valves.
But, it will be very noisy, so noisy, you will want a quiet free flowing muffler after about a minute of driving it. Noise does not always equal power, but does equal long term hearing damage.

[Tom Wesenberg]

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No pipes may also cause loss of scavenging and a net loss of power.
My neighbors Zundapp 250 wouldn't even run unless it had a pipe connected to the exhaust outlet.

[dean from bozeman]

When I was a madman (madboy?) in my eaarly 20's I borrowed my sister's '65 Mustang to go to a wedding. It was somewhat noisy because the muffler was going. After driving my date home (3:00am) I got on the highway and headed home (in the wrong direction). To me the sound was like driving a race car...or so I thought. I don't know how fast I was going but I had it floored. Well the tailpipe did break free and started dragging. It broke at the manifold and dragging the tailpipe caused it to keep ramming the gas tank and eventually it put a hole in the gas tank. So basically I was driving down the highway leaking gas and creating sparks with the dragging tailpipe. Before I ran out of gas the radiator blew up because of excessive overheating. The mechanic said that it was due to lack of back pressure.
During the next week I replaced the gas tank, exhaust system and radiator for my sister. The car never ran the same. Years later I made it up to my sister by buying her a nicely restored convertible.
Thank goodness that I didn't hurt anyone with my "race car driving". This was one of two episodes that turned my life around.
I relate this story because of the radiator blowing up. Does an engine run hotter without a tailpipe? This "experiment" seems to say so.

[lindy williams]

When Model A/B engines are used in airplanes (pietenpols) they use very short exhaust stacks, less than one foot long. I never heard of exhaust valve problems.

[Fordors]

The Zundapp needed the scavenging because it was a two cycle engine. Exhaust tuning will help a four cycle, but not to the same extent as that Z-250 which relied on it.
If the speedster were mine I would run a long lakes style pipe for the appearance but I'd put some baffles in it for two reasons- those guys wearing badges and also to be considerate of others. Not everybody enjoys open pipes.

[Crazydaddyo]

I've run this set up for over 10,000 miles and I have had no problems or tickets.

[jkeesey]

All i know is i ran a stock A engine last week with NO exhaust. just an open manifold and it did not want to rev up, it would pop and try to quit. I put on a set of leather gloves and held a stock exhaust stack onto the manifold and was able to rev it like normal. the engine would idle perfectly with no exhaust just not at higher rpm. Just what happened to me.

[ratamahata]

Originally Posted by Crazydaddyo

I've run this set up for over 10,000 miles and I have had no problems or tickets.

Just a bit of hearing loss!! Nice to see the banger!

[Frank Miller]

From my experiencing seeing Harleys with straight pipes put on the dynos I would never run them. Straight pipes work great at wide open throttle but are not great in the mid range. Amazingly the quieter 2 into one make the most power. I think putting some type of muffler on it that makes the sound you want will work best. Without major porting I think there will always be a bottleneck at the valves.

[BILL WILLIAMSON]

Originally Posted by Tom Wesenberg

No pipes may also cause loss of scavenging and a net loss of power.
My neighbors Zundapp 250 wouldn't even run unless it had a pipe connected to the exhaust outlet.

My Lord, Tom,
I had one like that too! When I mention that now, folks say, "You had a WHAT???? Muffler was rotted, put a chrome rear muffler offen' an XKE Jag. Ran good! I can still hear it, ZUN-DAPP-DAPP-DAPP-DAP Bill W. (Can't ride bikes anymore, almost fell offen' my mobility scooter last Tuesday!)

[Marco Tahtaras]

If you decide to run any type of open pipe I strongly suggest you have two-three different size reducing end caps made to partially restrict flow at the exit. You can swap them and pick the one that produces the best performance. You WILL find a noticeable improvement over an open pipe.

If you run it very much you will be glad we communicate here in writing!

[Pete]

Running the exhaust right out of the block will NOT cause warped valves...Old wives tale. It does probably result in the least ammout of horsepower from an engine though.
I tried several different configurations of headers on one of my race engines and the "W" type made the most hp on the dyno. It ran into a 22 inch collector with a bypass and cover plate into a nice quiet muffler for street use..

[Rowdy]

Thanks Pete, figured it was an old wives tale as in my experience I have never seen anything that suggested it was true. Posted it as a precaution just incase I was wrong. Backpressure is a good thing at the correct amounts. Rod

[BRENT in 10-uh-C]

Here was a set that we ran on my wife's speedster...both on the track and on the road;










We drove this engine hard and never saw any adverse affects with valves.

As for you "not running it too hard", ....Yeah Right!!

[PC/SR]

Pete: What kind of intake manifolds?: Almost looks like a 4 port, or at least 4 runners, adapters for the carbs?

[Jason in TX]

Only thing it will hurt is your neighbor's ear drums and your chances of being invited over to their house ever again!