Hotrods Dyno numbers

[Big Daddy Funk]

I have finished with the engine performance upgrades on the Hotrod (80 Special) The final streetable dyno numbers are 95hp and 72ftlbs of torque at the wheel. These numbers came off a new state of the art dyno, so I believe they are trustworthy. Without air filters and exhaust baffles the numbers picked up 3 more horses and a couple ftlbs of torque but you wouldn't want to ride it that way. The bikes torque curve starts sooner and climbs quicker than it did before. It pulls scary hard to the redline. I'll see if I can figure out how to post the dyno sheet.
The upgrades were: 1196 Big bore kit, Megacycle cams. Dynojet carb kit, 4into1 header, ported and flowed head, Mikes air pods and Green coils.
I learned alot about these engines through trial and error. The main thing I learned is that they love to breath, getting air in and out of these motors is critical. They are also very sensitive to A/F mixture.
I did do all the work myself but I would like to thank Dan Hodges posts for leading the way, as well as Brad Prong at Prong Built for giving me full access to his shop and dyno as well as his help.
Next up for the Hotrod is XS Chop's chain drive conversion. When completed I'll post the new dyno numbers.
Rick

[bobber]

thanks for the info,always wonderd what sort of power these bikes could put out.

[Montreux_Blue]

It increased without exhaust baffles, so it does better without scavenging??? Every XS I've been around without baffles just made a lot of noise and had no power. Maybe I'm reading your post wrong.

[DiverRay]

I think that without the filters, and no baffle in the header, it CAN breath better. That works well on some tracks, but will get you a ticket for noise on the street.
95 RWHP is a GOOD number, and the 72 LB Feet of twist is even better! You have gained a LOT over stock, running the so called gas we now have. I have to now HOPE I can make the 150 RWHP I'm looking for!! I may settle for 125 RWHP.

[Big Daddy Funk]

Scavaging

A few things surprised me too. Any kind of restriction on the intake side had a corresponding drop in numbers. Even velocity stacks with no filters had lower numbers than open carbs. On the exhaust side I made a 2" straight flow through silencer and still cost power. I think the scavaging effect is largely a result of the exhaust pulses at the collector creating vacuum effect on the pipe side of the unopened exhaust valves. more like siphoning.
I tried with a lot of different things and found that this engine really wants to move air in and out the fastest possible way. Having said that I would have thought a richer A/F mixture would be required but, not so. I ended up using 132DJ main jet rather than the 138DJ in the Stage 3 Dyno jet kit.
Thx Rick

[79XS11F]

Hey Rick, The real difference will be seen when you get the chain drive kit installed. The weight savings will make the bike fell like a 650. My modified 78 model now pretty much goes up onto the main stand by herself. Rolling her around is also a lot easier. I'm going to have to get her weighted this spring.

Rob

[Big Daddy Funk]

Lose the spare tire?

Hey Rob. I should have included that I expect a lighter more nimble bike due to reduced weight. The weight reduction will also help the HP to weight ratio. I suppose I could have lost 50 lbs myself but it would take way more time and money.
The drag bike boys tell me that getting rid of u joints, drive shafts, planetarys and such should net me 15-20%. I'm not convinced of that number but I plan to find out. Rick

[tw1980]

Good job Rick looks to me like you put up some good numbers and had a lot of fun doing it.I don't know what grind you had Megacycle put on your cams but mine really kick at about 5800 to 9100.I hope you like your chain drive mod.I think you can install a wider rear tire as well.

Terry

[Montreux_Blue]

I guess if it works on the dyno then it works. And your right about the scavenging, it's all about tuning the exhaust pulses to increase the velocity of the next exhaust pulse.

[Big Daddy Funk]

Fun-Wow

Good job Rick looks to me like you put up some good numbers and had a lot of fun doing it.I don't know what grind you had Megacycle put on your cams but mine really kick at about 5800 to 9100.I hope you like your chain drive mod.I think you can install a wider rear tire as well.

Terry

Yes I must admit I had a great deal of fun and excitment trying different combinations and seeing the results. Some of my previously held theories got blown away. Seems an old dog can learn new tricks.
I have the the bike set up more like a jack rabbit. It now starts a steep torque climb at about 2500 rpm and reaches 60ftlbs of torque by 3500rpm in a fourth gear roll on. My shift point in a drag race is now 7500rpm. That's the point where the HP climb slows. By 8500 rpm & 131mph the HP flattens out.
As for the cams, the intake is 380 lift and 261 duration, opening @ 23 BTC and closes @58 ABC, degreed with 0 lash @40deg. lift, lobe center is 107.5
The exhaust has the same lift and duration with a 108.5 lobe center. It opens at 50BBC and closes@ 22ATC.
If I had it to do over I would go with webcams as they are a little hotter and you can still use standard shims. I would also go with stock exhaust valves and 39mm intakes.
I would be happy to share my experiences and specifics with anyone doing a build. Reading Ken Talbots Dyno daze thread is a must.
And yes a fatter rear tire is a must.
Thx Rick

[ManitoulinLad]

All I can say is WOW! Man alive hope this is the bike you bring up to Manitoulin for the ride this summer with Slo Mo & the boys. By then you'll have the chain drive & fat tire = performance mods to the max. Would love to have a heavy gawk at that one, with no time limit of course. Congrats on the work done - Dan

[Ivan]

Reading Ken Talbots Dyno daze thread is a must.

Where is that? I searched for "dyno daze" and came up with three threads, none were it, also looked for all threads started by Ken and no joy.

[Ken Talbot]

Reading Ken Talbots Dyno daze thread is a must.
Thx Rick

Maybe some of Dan Hodges' dyno posts...

[Big Daddy Funk]

oops

Maybe some of Dan Hodges' dyno posts...

My bad, The posts were: Slide springs and stuff, Dyno jet daze, An excercise in insanity, Valve springs, Flow grooves around seats, Port surfacing, Exhaust porting, All by Dan Hodges. Saved me a ton of headaches by pointing me in the right direction.
With any luck, I will be bringing the Hotrod to Manitoulin this summer.
Thx Rick

[tw1980]

Hey Big daddy I forgot to ask did you play with the ing or valve timing?

Terry