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Dyno run
- Thread starter Gundy
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OP
Gundy
Luke Skywalker
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Limited prep H/P Midget. Man, Tom's a lucky guy.
I want one. The graph part was hard to get on tape
even when I moved the camera. This is the best I could do after several other runs/takes.
Shot it with a Nikon D90 on tripod.
It took me over an hour to upload those 45 seconds.
I have some other footage, like with Hap explain' chit
and stuff but those may appear AFTER the FBCC next meeting.
Hehe...FBCC exclusive.
I can't wait to strap ol Mimi on the roller.
Here is Tom's Midget. Lucky dog.
https://www.youtube.com/watch?v=fvIpLgVNDvo
Tip: best viewed in HD
I want one. The graph part was hard to get on tape
even when I moved the camera. This is the best I could do after several other runs/takes.
Shot it with a Nikon D90 on tripod.
It took me over an hour to upload those 45 seconds.
I have some other footage, like with Hap explain' chit
and stuff but those may appear AFTER the FBCC next meeting.
Hehe...FBCC exclusive.
I can't wait to strap ol Mimi on the roller.
Here is Tom's Midget. Lucky dog.
https://www.youtube.com/watch?v=fvIpLgVNDvo
Tip: best viewed in HD
OP
Gundy
Luke Skywalker
Offline
Falkon said:
Pics don't do it justice. I think Hap massaged about 5 or 6
more horses out of it during the runs. Really neat stuff.
This is basically a stock engine too.
Stock head, no porting, stock carb and limited to 11-1 compression.
I was impressed.
I shot some rear stuff just for the sounds. It drew shop guys
from other places to see what the heck is THAT!
Jim_Gruber
Yoda
Offline
So what was the HP Output on the dyno after Hap massaged?
SilentUnicorn
Yoda
Offline
Lord what a lovely sound- i keep playing it over and over.....
m
m
OP
Gundy
Luke Skywalker
Offline
Jim_Gruber said:
Hap got the AFR dialed in at about 13 at WOT and advanced the timing a couple of degrees. That netted about 80 hp at
the rear wheels.
The dyno guy estimates about 20% loss through the drivetrain.
So Tom's Midget is putting approximately 100hp at the flywheel.
Pretty amazing for a "stocker".
It made the top hp from say 6.2K to 7.2K. Very slight drop off
to the 7.6K on this run.
I think Tom feels better about extending the "redline" during
needed times in a race now.
He's using a 3.9 rear gear and a sc/cr box.
I don't know the cam profile. It's one Hap recommends for
this class of engine.
They have some limitation in Tom's SCCA class regarding cams.
Hap Waldrop
Yoda
Offline
I think I ended getting to about 81 hp at the rear wheels, make some jet height changes and put a little more advance timing into it. This is our first time at this dyno, we have another SCCA limited prep 1275 we seen a high of 100 HP at the rear wheels and pretty decent average of mid 90s on a bunch of runs on different days on a dfferent chassis dyno. We'll have another SCCA LP 1275 Bugeye on the same chassic dyno with a new engine, so it will give us a bit more idea if this dyno reads lower than the other one we have used in the past. I always tell folks forget the HP and torque numbers from one dyno to the next, just tune that car, that day, on that dyno as good as you can get it, in the end we were running about 13.0 on air ful ratio at 7000+ rpm, and went as far as 7700 to see where the cam quit pulling, the car has amazing broad powerband bascily it was near high HP output as 6000 rpm, only gain a few HP on it's way up to the low 7000s.
The LP 1275 engine allow Spridgets to run in SCCA H production class with lesser mods than the full prep 948s and 1098s, they cost alot less to build, and they last a lot longer between rebuilds. The heads are only allowed 1" of gasket porting, but we flowbench test a bunch of stock heads to find the very best flowing heads, and that makes a big difference, Tom bascily didn't do alot of that, so I think thats why he may be down on HP compared to the other LP motors I have built, while I did do some component work on Tom's engines, I didn't build it and it's not nearly as trick as the ones I've build. The cam he is running was actually one I changed out of a vintage full prep 1275 and sold to Tom the cam and lifters, it was a Elgin Cam, about .355" cam lift ,and advertised duration of about 300 degrees, with stock rocker arms (rules required), that puts on right at the max valve lift rule of .450". These engine can run a max compression ratio fo 11.0. While these are stockish engine in appearence they are far from that, they have the very best flowng stock heads we can find, the best flowing twin HS2 intakes we can find, we have to run stock connecing rods, but we lighten them 100 grams per rods and polish the beam and balnce them within a gram as wel as use ARP rod bolts in them, stock cranks are also required but lightening is allow, so we wdge lighten them and remove a average of 3 pounds from the stock cranks, then run a 9 pound aluminum flywheel and on most of the race engine, also a Tilton type racing clutch. WE have to run stock valve size in the ehad, but we re profile the valve on the head to be flatter and flow better, I also machine the guide to be less daimeter in the section that protrudes into the port, to help flow number as well. We seond an enormous amount of time prefected the stock rocker arm assembly, as for center the rocker arm over the valve stem, installing solid sapcer and then finding 8 stock rocker arms that represent the most ratio, and net us near max vlave lift per the rules, stock rocker arma tend to vary in ratio a bit. They have vernier timing gears on them to perfectly dial the cam timing in. We use ARP fastner everywhere we can, rods, head studs, sometime main studs, and flywheel. At the end of the day we just making a stockish .040 over , cammed up, slighty higher than street gas compression ratio engine run as much and more HP as as hot rodded 1380cc street, ported head w/ big valves engine and the only real advantage we have over a really tricked 1380 is 1 point more compression, so pretty impressive HP numbers when you think about how little we are able to do to these engine to produce HP under the rules. In alittle over 2 years of R&D we were able to get these LP 1275 motors outpower vs the 16 to 1 dry sump 948 full prep engines by as much as 20 HP, we about even with or maybe just a bit shy of what a full prep 1098 can do HP wise, but we get a huge weight break on the car by running the LP1275 and it cost ahlf as much to build and last twice as long, I just had a custmer finish a 20 race weeken run with one of these engine, take it apart, clean it up, check over everyhting put him new rings, and bearings in it and it's ready to go again. The key is these engine make their max HP at 7000-7200, where the full prep 948 motors need to tuen 8000-9000 rpms to get max power, so these engine last alot longer when done right.
The LP 1275 engine allow Spridgets to run in SCCA H production class with lesser mods than the full prep 948s and 1098s, they cost alot less to build, and they last a lot longer between rebuilds. The heads are only allowed 1" of gasket porting, but we flowbench test a bunch of stock heads to find the very best flowing heads, and that makes a big difference, Tom bascily didn't do alot of that, so I think thats why he may be down on HP compared to the other LP motors I have built, while I did do some component work on Tom's engines, I didn't build it and it's not nearly as trick as the ones I've build. The cam he is running was actually one I changed out of a vintage full prep 1275 and sold to Tom the cam and lifters, it was a Elgin Cam, about .355" cam lift ,and advertised duration of about 300 degrees, with stock rocker arms (rules required), that puts on right at the max valve lift rule of .450". These engine can run a max compression ratio fo 11.0. While these are stockish engine in appearence they are far from that, they have the very best flowng stock heads we can find, the best flowing twin HS2 intakes we can find, we have to run stock connecing rods, but we lighten them 100 grams per rods and polish the beam and balnce them within a gram as wel as use ARP rod bolts in them, stock cranks are also required but lightening is allow, so we wdge lighten them and remove a average of 3 pounds from the stock cranks, then run a 9 pound aluminum flywheel and on most of the race engine, also a Tilton type racing clutch. WE have to run stock valve size in the ehad, but we re profile the valve on the head to be flatter and flow better, I also machine the guide to be less daimeter in the section that protrudes into the port, to help flow number as well. We seond an enormous amount of time prefected the stock rocker arm assembly, as for center the rocker arm over the valve stem, installing solid sapcer and then finding 8 stock rocker arms that represent the most ratio, and net us near max vlave lift per the rules, stock rocker arma tend to vary in ratio a bit. They have vernier timing gears on them to perfectly dial the cam timing in. We use ARP fastner everywhere we can, rods, head studs, sometime main studs, and flywheel. At the end of the day we just making a stockish .040 over , cammed up, slighty higher than street gas compression ratio engine run as much and more HP as as hot rodded 1380cc street, ported head w/ big valves engine and the only real advantage we have over a really tricked 1380 is 1 point more compression, so pretty impressive HP numbers when you think about how little we are able to do to these engine to produce HP under the rules. In alittle over 2 years of R&D we were able to get these LP 1275 motors outpower vs the 16 to 1 dry sump 948 full prep engines by as much as 20 HP, we about even with or maybe just a bit shy of what a full prep 1098 can do HP wise, but we get a huge weight break on the car by running the LP1275 and it cost ahlf as much to build and last twice as long, I just had a custmer finish a 20 race weeken run with one of these engine, take it apart, clean it up, check over everyhting put him new rings, and bearings in it and it's ready to go again. The key is these engine make their max HP at 7000-7200, where the full prep 948 motors need to tuen 8000-9000 rpms to get max power, so these engine last alot longer when done right.
BlueMax
Jedi Warrior
Offline
Hap, Job well done on the HP gain, it sure is amazing what a little tweaking can do!!! Awesome job Gundy on the Video, crystal clear on the HD, it doesn’t get any better than that. It will be interesting to see how the big bore 1380’s stands against the LP engines since I’m playing in the 1380 group!
Hap Waldrop
Yoda
Offline
We'll know a bit more about the true potential of LP1275 when we get Dick's new motor on there, I expect we will se higher numbers, unless this dyno just reads low, a LP 1275 and good 1380 should make similar HP, just make it a bit differently, the higher CR and the cam profile has alot to do with how this less modded motors make their power. You could put a good ported head on it and some thru bore carbs and it would probably jump 20 HP.
Hap Waldrop
Yoda
Offline
Gundy said:
Sure, not like it's up to him anyway
, you know Dick, he's cool, he'd love for you to film it. Probably the next couple of weeks, he still making repairs to the chassis, but he's getting close to sticking the new bullit in there. Hey, it will be another excuse to go eat some good ole Dukes sandwiches :banana:
We can title the series, "AARP race drivers gone gone wild"
OP
Gundy
Luke Skywalker
Offline
Hap Waldrop said:Gundy said:
Sure, not like it's up to him anyway
Hey, it will be another excuse to go eat some good ole Dukes sandwiches :banana:
We can title the series, "AARP race drivers gone gone wild"
Now ya got me...Dukes sandwiches and sweet tea no Hummingbird
could refuse.
Gimme a call when the time is near at hand.
:thumbsup: