Starter for my WWI fighter! (250 cid Ford with PSRU)

[XPC66]

OOOPS..... JW and I are on at the same time....

The reason I feel that 190 psi sounds too low, is BMEP is the pressure a piston sees when the engine is running. 190 psi sounds like cranking pressure.

190 psi is very good for a petrol engine. Some engines run as low as 50 psi, but the garden variety petrol engine these days is between 100 -200, a forced induction is between 200 -350. A diesel is around 350. A natural gas engine can achieve between 70 and 85% of an equivelent diesel pressure.

Because BMEP has a predicatable relationship with engine torque, you can calculate it and vice versa.

Then you have indicated mean effective pressure (IMEP)

You are probably thinking peak cylinder pressures. e.g 2600psi for diesel, 1800 for natural gas, etc. The peak pressures are all over the shop from one engine to another and needs to be taken by imperical measurements.

 

[Anonymous]

Just to clarify, The 280-300 number is before it goes through the PSRU. After it comes out the other end the torque is multiplied to 610-652 ft/lbs torque!!

What % mechanical losses?

 

[Von Writter]

Just to clarify, The 280-300 number is before it goes through the PSRU. After it comes out the other end the torque is multiplied to 610-652 ft/lbs torque!!

What % mechanical losses?

Around 1.5-2% according to the PSRU mfg.
TW

 

[Lazy JW]

I was using the formula posted here by StrangeRanger to calculate the BMEP.

Torque=BMEP x CID/ (48xPi)

Remember, the BMEP is a measurement of the EFFECTIVE pressure after all of the negative forces have been subtracted.

A constant 190+ BMEP is significant. At least he will get to run Avgas 8)

Von Writter,
Are you planning to actually fly that thing with the Duraspark 2 ignition ?
Joe

 

[Von Writter]

Von Writter,
Are you planning to actually fly that thing with the Duraspark 2 ignition ?
Joe[/quote]

I'm using a Mallory Hi Fire 6 ignition on it, with the Dura Spark distributor.
It should be much more reliable than a Magneto, there is a reason you need two, they are always giving Problems. On my last Fighter I had one fail outright, thankfully I still had the other one ;o)

 

[Lazy JW]

Well, that's probably better than the DS2 module, of which I have personally had no less than three fail (plus the one that I burned up by leaving the key on). There have been reports here of failed MSD modules as well, not sure about the Mallory units as they are not as popular but I can't imagine them being much different.

Reckon I am a bit old-fashioned, but a well maintained breaker point distributor is pretty hard to beat for absolute reliability.
Have fun!
Joe

 

[Does10s]

Von Writter,
To bad the FSPP Aluminum head is not quite done yet!
It would be a quick way to lose about 30lbs. from the nose.
Will

 

[Von Writter]

Von Writter,
To bad the FSPP Aluminum head is not quite done yet!
It would be a quick way to lose about 30lbs. from the nose.
Will

I wish it were ready! Not so much for the weight, I need a fair bit in the nose. But for the Power!!! More torque is good! ) I weighed my engine last night, and it with the PSRU minus the starter carb,headder,and Alt. was 300 lbs. That was much lighter than I thought it would be, I wonder if my scales are whacky???

 

[Von Writter]

Well, that's probably better than the DS2 module, of which I have personally had no less than three fail (plus the one that I burned up by leaving the key on). There have been reports here of failed MSD modules as well, not sure about the Mallory units as they are not as popular but I can't imagine them being much different.

Reckon I am a bit old-fashioned, but a well maintained breaker point distributor is pretty hard to beat for absolute reliability.
Have fun!
Joe

I went with a Mallory unit because they are "Supposed" to be a bit better than the MSD, and because they have the multi spark through their entire range. I'll be mounting it in as cool a location as possable and on rubber isolation mounts as well. Vibration is Hell on electronic circits!
I hope that will make the differance.
TW

 

[jamyers]

And don't forget that you could run dual / switchable ignition boxes, either mallory or msd.

Love the pictures!

But of course you know that not using an old radial engine, you'll be missing out on the castor oil spray-bath while flying...unless you're adding a tank, pump, and nozzle? :roll:

 

[Von Writter]

And don't forget that you could run dual / switchable ignition boxes, either mallory or msd.

Love the pictures!

But of course you know that not using an old radial engine, you'll be missing out on the castor oil spray-bath while flying...unless you're adding a tank, pump, and nozzle? :roll:

The Fokker DVII is an INLINE aircraft not rotary so I guess I'll miss puking my guts out and messing my flight suite

 

[jamyers]

Inline? Doh!!!
Well, still - if you wanted that WWI "feeling"...

 

[Anonymous]

I wish it were ready! Not so much for the weight, I need a fair bit in the nose. But for the Power!!!

You may be able to get an Argentine SP head in aluminum, if the guys here in the US have any:

http://fordsix.com/forum/viewtopic.php? ... luminum+sp

I went with a Mallory unit because they are "Supposed" to be a bit better than the MSD,

I haven't ever heard of one failing....but they aren't as common.

 

[Anonymous]

With a name like Von Writter, I was willing to bet that you weren't building a Spad.
Doug

 

[Lazy JW]

And don't forget that you could run dual / switchable ignition boxes, either mallory or msd...

I didn't know you could do that, sure would ease the pucker factor. I was an avionics tech in the Marines, an experience that caused me to have a healthy distrust for all things solid state in critical applications unless there is a redundant system to keep you flying. Also, 23 years in sawmill maintenance has only increased my appreciation for simplicity. The fact that I can take a set of points out and REALLY look them over puts them way up on my reliability chart. I know of no way to do that with a transistor, and I have replaced plenty of them that failed.
Joe

 

[Anonymous]

I'm using a Mallory Hi Fire 6 ignition on it, with the Dura Spark distributor.

Peace of mind:

http://www.turbomustangs.com/smf/index. ... ic=56866.0

 

[jamyers]

I know of lots of Buick guys running MSD's and no reports of failures. I think that with some of the newer stuff (LS-X engine coils, etc) there may be issues, but the "old" stuff seems pretty bulletproof. Your mileage may vary, of course.

I'd bet that any of the aftermarket systems can be doubled-up for a backup ignition. I'm in the middle of putting together a "glovebox" ignitnion backup using a GM HEI module and trailer wiring/connectors so that if my MSD box ever fails I can swap in the backup with two simple connectors. Probably not what you'd want to be doing while gliding along at 1,500 feet, but with some more thought and scratch paper....

Here's MSD's instruction page, there are .pdf files on wiring dual MSD boxes with a selector switch, dual coils, GM HEI, Ford Duraspark, etc: http://www.msdignition.com/downld1.htm

 

[Von Writter]

I'm using a Mallory Hi Fire 6 ignition on it, with the Dura Spark distributor.

Peace of mind:

http://www.turbomustangs.com/smf/index. ... ic=56866.0

That is just what my research indicated, MSD was prone to fail but lots of Good things heard about the Mallory units! Thanks for the link!
TW