My '59 Enfield /Indian 750cc Chief High Compression Build

[Scottie J]

So, after fighting a nasty head cold all week (still not a 100%   ) I finally made a little more progress on the chassis.  I decided to build my own custom solid strut out of pieces of steel that I happened to have laying around.  I used a 1 1/4" steel pipe with a 5mm wall for the main shaft, modified a piece of 1"x2" 3mm wall steel square tubing for a clevis and a 7/8" Grade 5 bolt for the adjuster.  I'm pretty happy with the results, tho I wish I could get it to go just a hair lower.  If it bothers me enough I'll trim it down and redo it, but I think it will be ok.  Man, I have to admit that not welding/fabbing in about 3 years has got my arse a little rusty.  Ummmm, pun intended.    Doesn't help that my eyes aren't what they used to be either.  Not that my welds are coming out bad or anything, but they definitely aren't as pretty as they used to be.    

Also received word from Tom at Ace Performance that my customs valves arrived earlier this week and that Mondello's is going to start working my heads over towards the end of next week.    











Scottie J

[Scottie J]

Also, I forgot to share this info previously, I somehow spaced it out.     This was the information that Tom Lyons at Ace Performance shared in regards to my RE 700cc twin heads preliminary flow bench results.

We have the baseline flow chart for the 700 twin.
Since the ports and valves appeared unmodified, this is probably a generally representative flow chart for the RE twins of that era.
Testing was done at 28" H2O on Mondello's Superflow Flow Bench.

Lift        Intake cfm   Exhaust cfm
.050"       19.7             20.5
.100"       44.8             40.4
.150"       71.0             61.3
.200"       94.2             77.4
.250"      109.2            90.0
.300"      118.0            98.4
.350"      126.6           107.5
.400"      130.9           112.0

The max lift we tested of .400" was as far up as the stock valve gear would allow, before the retainer was banging against the valve guide, so no higher lift testing was possible with unmodified valve gear.

In the plan for this head is to establish a new max lift height via custom valve train parts. While the flow numbers appear small, remember that this is a pair of 350cc cylinders, and the ports and valves are smaller too, to suit the normal application of this engine on the street in 1958. It is a bit behind the standard Bullet with the 500 cc engine, but not too far back. It might not be able to come up to Fireball flow standards, due to the fact that it has 2 smaller cylinders and smaller everything for each intake, but it should do quite well after modding, and the supercharger will have to do the rest.

Enjoy the info!
Not many places to find this kind of info on these old engines.

Scottie J

[Sumner]

Also, I forgot to share this info previously, I somehow spaced it out.    This was the information that Tom Lyons at Ace Performance shared in regards to my RE 700cc twin heads preliminary flow bench results.

We have the baseline flow chart for the 700 twin.
Since the ports and valves appeared unmodified, this is probably a generally representative flow chart for the RE twins of that era.
Testing was done at 28" H2O on Mondello's Superflow Flow Bench.

Lift        Intake cfm   Exhaust cfm
.050"       19.7             20.5
.100"       44.8             40.4
.150"       71.0             61.3
.200"       94.2             77.4
.250"      109.2            90.0
.300"      118.0            98.4
.350"      126.6           107.5
.400"      130.9           112.0

The max lift we tested of .400" was as far up as the stock valve gear would allow, before the retainer was banging against the valve guide, so no higher lift testing was possible with unmodified valve gear.

In the plan for this head is to establish a new max lift height via custom valve train parts. While the flow numbers appear small, remember that this is a pair of 350cc cylinders, and the ports and valves are smaller too, to suit the normal application of this engine on the street in 1958. It is a bit behind the standard Bullet with the 500 cc engine, but not too far back. It might not be able to come up to Fireball flow standards, due to the fact that it has 2 smaller cylinders and smaller everything for each intake, but it should do quite well after modding, and the supercharger will have to do the rest.

Enjoy the info!
Not many places to find this kind of info on these old engines.

Scottie J

Hot Rod published a formula that predicts HP based on head flow with a >65% intake/exhaust ratio and maximum efficiency (cam/exhaust/intake/etc.) and number of cylinders.  

I made a spreadsheet around it where you could adjust the efficiency for a non-ideal combinations and also put in boost levels if you weren't NA and also input the Altitude (altitude pressure adjustment).  If you are interested I could e-mail it to you or post it with my other spreadsheet.

Using 131 cfm and 2 cylinders and 95% efficiency (100% would be all ideal components) it shows for your situation 64 HP naturally aspirated.  With 12 lbs. of boost 116 HP at sea level and 106 HP at 5000 feet.  If you dyno the motor I'd be interested in how close their formula is to what you make HP wise (100% efficiency would be 67 HP),

Sum

[Scottie J]

Hot Rod published a formula that predicts HP based on head flow with a >65% intake/exhaust ratio and maximum efficiency (cam/exhaust/intake/etc.) and number of cylinders. 

I made a spreadsheet around it where you could adjust the efficiency for a non-ideal combinations and also put in boost levels if you weren't NA and also input the Altitude (altitude pressure adjustment).  If you are interested I could e-mail it to you or post it with my other spreadsheet.

Using 131 cfm and 2 cylinders and 95% efficiency (100% would be all ideal components) it shows for your situation 64 HP naturally aspirated.  With 12 lbs. of boost 116 HP at sea level and 106 HP at 5000 feet.  If you dyno the motor I'd be interested in how close their formula is to what you make HP wise (100% efficiency would be 67 HP),

Sum

That may very well be the exact same formula that Tom is using because the figure he came up was very close to that.  So we must be in the right ball park. 

Scottie J

[Scottie J]

Seldom Seen Slim - I'm curious, what is the coefficient drag for that Charlie Toy LSR2 fairing?  I'm trying to calculate some different possibilities.

Scottie J

[Seldom Seen Slim]

I don't know. Scottie.  I don't know if it's ever been tested.  Heck, it's hard enough to determine what benefits, if any, there are to using it (or some other aftermarket design).  I've got the comfortable feeling that I went faster with it on my bike than with the factory 'glass, but that's about as far as I can say.  some others may have done (as accurate as possible) tests - maybe coast downs in benign winds over measured distances or something - but I've heard nothing about a real measurement of Cd for the toy fairing.  Scott Guthrie had a good-sized hand in the original design - maybe he's got some data.  I sure don't.  Sorry.

[Scottie J]

Ok, thanks anyways.  I was just curious.  Could someone please give an estimated average cd for any random bike with a good LSR fairing?

Scottie J

[TheBaron]

The best OEM Cd I've seen is for the Suzuki Hayabusa...

It is .561

A 125cc GP bike I saw the data on was .622......

I'd use .600 to start with....

Robert

[JimL]

I ran my speed, frontal area, and weight through this:
http://www.rbracing-rsr.com/aerohpcalc.html

I kept adjusting the Cd until I got a power number I might possibly believe.  My bike has the Charlie Toy fairing and tail, with the lower tail closed and the front of the fairing completely closed (no cooling inlets).

With speed of 164, frontal area 5.5, and all-up weight at 600, it says a Cd of .45 would be about 90 hp.  I also tried another calculator that suggested 82 hp with a Cd of .48.

All I know is I have 645cc pushrod twin with a time slip for 163.8, several prior runs exiting above 160 into light headwinds....all on gasoline unblown.

The tail really helps, but I still dont believe 90 hp from such a small twin.  Could be, we are missing something with these calculators?

JimL

[Sumner]

....With speed of 164, frontal area 5.5, and all-up weight at 600, it says a Cd of .45 would be about 90 hp.....JimL

Plugging those numbers into the spreadsheet on my site (use the one for a lakester -- input all tire/wheel inputs as 0) I get 74 RWHP needed.

For a Cd of .48 I get 80 RWHP needed.  For the .561 for the  Suzuki Hayabusa I come up with 92 HP,

Sum

[TheBaron]

The fairing I'm using allowed an old school 70's road racing factory 750cc twin to go 160 mph with 90 hp (no tail,, just the standard seat/tail cone of the day).

My guess is that your 650 in making 70 to 80 honest hp (any more and it would most likely be a grenade) and that tail is maybe worth about 20 hp...

Those are real strong numbers you have run,,,good job !

The air density assumptions could be a little off in those programs and that will make more difference than it first appears....

When I was crewing Reno air racers, we watched the density altitude like a hawk....  Humidity and temperature change it a lot... as the DA goes up the air mass to the engine and cooling system goes down, but so does the resistance of the vehicle moving through the air... Just how much one washes out the other can be quite vehicle dependent to get calculations to output exactly correct numbers.

Robert

[JimL]

Interesting that the stock honda engine was rated 67 hp, which is what Scottys head flow shows available.  I would believe I am around 75 hp, which would be 8 hp over stock.  It looks like if he could get just 100 hp at altitude, blown, he would be almost 175 mph ride with good streamlining (including APS type tail)?

Aero is cheaper than horsepower, and requires less maintenance from salt damage.  Gear to the moon, scotty, and dont spare the whip!

JimL

[Scottie J]

Interesting that the stock honda engine was rated 67 hp, which is what Scottys head flow shows available.  I would believe I am around 75 hp, which would be 8 hp over stock.  It looks like if he could get just 100 hp at altitude, blown, he would be almost 175 mph ride with good streamlining (including APS type tail)?

Aero is cheaper than horsepower, and requires less maintenance from salt damage.  Gear to the moon, scotty, and dont spare the whip!

JimL

That's what I am seeing too.  Granted these are all calculators, but they seem to be pretty accurate.  The figures I was coming up with indicated that with 100hp I should be able to break 140mph on the salt without a fairing and flirting with the 165-175mph mark with a fairing.  If it turns out that the motor is more capable than anticipated and I can crank it to about 125hp @ 7000 RPMs I'll be knocking on the door of the 200 club with a fairing.  Tom is thinking that 125hp isn't UNrealistic with our build plans.       Obviously, I might have to have a couple different custom rear sprockets made up.  But it's all part of the fun, right?

Scottie J

[bak189]

You break 200mph. on your "Cornfield" and you got $200.00 of my money....(Remember Single Engine only)

Offer still good.........................

[Sumner]

.... The figures I was coming up with indicated that with 100hp I should be able to break 140mph ..without a fairing and ..... 165-175mph ...with a fairing.  If ....I can crank it to about 125hp @ 7000 RPMs I'll be knocking on the door of the 200 club with a fairing.....

Let's say you could run 175 on the 100 HP then you would need 149 HP to run 200.....

http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html#Horse%20Power%20Needed

Using Jim's numbers again....

With speed of 164, frontal area 5.5, and all-up weight at 600, it says a Cd of .45 would be about 90 hp.

.... and running 200 mph I come up with 136 RWHP.  I don't know what the drivetrain losses are on a bike compared to a car but even 10% would equate to 152 crank HP. 

If you use some of the higher Cd figures quoted like say the .561 then the RWHP goes up to 168 HP.

Getting into the 2 Club is a big achievement but not the only achievement there is to be had on the salt.  Setting a record with that bike within the first couple years of running would be a big achievement and one that would make you mighty proud.  There are a lot of records under 200 that are a lot harder to attain than a number over 200. 

For instance I'd much rather have the records John and Eric have under 200 MPH with their 50cc, 100cc and 125 cc Motorcycle Streamliner (145+, 151+ and 186) ...

http://buddfab.net/buddfabhomepage.html

.....than say a 250 mph record with my lakester if that would ever happen.

Enjoy the journey,

Sumner