Dyno Day!

[scottiec]

Hey Gang,

As some of you may remember, after 1400 miles of gel coat driving I had to build a new motor. Yesterday my extremely talented friends and I took it to the dyno we rented. I am more than pleased with the numbers. It looks like all of my measuring, parts selection, research, and beer drinking paid off!

Here are the specs and where we landed:

302 with Trickflow twisted wedge 170 heads, ford B-303 cam (the "bottleneck in this equation), edelbrock rpm, and a Brawler 600 cfm double pumper. We ended up settling on initial timing of 16* and total timing of 32* all in at 2750 rpm. Also leaned it out a bit by dropping two jet sizes on the primary and secondary bringing me to 64/70 jets. SAE correction was 330whp/323 tq. Standard correction was 338whp/330 tq.

[jrcuz]

I just watched your video on youtube, Congrats!
JR

[scottiec]

I just watched your video on youtube, Congrats!
JR

Thanks JR! Super happy with how much power this thing made.

[cgundermann]

Not to shabby! More than enough to get you in trouble...

Sounds great,

Chris

[GoDadGo]

When you are making 1 HP per cubic inch, with a pushrod V-8, you are doing well.
When you are making more than 1 HP per cubic inch, then you are doing Great.
When you are making more than 1 HP per cubic inch at the rear wheels; You Are Kicking Some Asphalt My Friend!

Well Done Mr. Scott, Well Done!

https://youtu.be/t9SVhg6ZENw

[scottiec]

When you are making 1 HP per cubic inch, with a pushrod V-8, you are doing well.
When you are making more than 1 HP per cubic inch, then you are doing Great.
When you are making more than 1 HP per cubic inch at the rear wheels; You Are Kicking Some Asphalt My Friend!

Well Done Mr. Scott, Well Done!

https://youtu.be/t9SVhg6ZENw

LOL thanks for the video. The car feels very strong.

[scottiec]

Not to shabby! More than enough to get you in trouble...

Sounds great,

Chris

Thanks Chris. You could feel it in your chest, so loud on the dyno.

[VAHokie]

Congrats, Scott! A lot of time and energy getting to that point - well done!

[phileas_fogg]

That's GREAT! I love the head bob as your buddy is winding it out. Congratulations, and WELL DONE!


John

[scottiec]

That's GREAT! I love the head bob as your buddy is winding it out. Congratulations, and WELL DONE!


John

lol I know. After dropping a couple of jet sizes, he was happy with the AFR

[RJD]

Congrats Scott. Well done!

[scottiec]

Congrats Scott. Well done!

Thanks man! And congrats on your first start!!! We will be cruising in no time.

[Avalanche325]

Whooohooo! I loves me some dynos.

Dyno.jpg

[scottiec]

Whooohooo! I loves me some dynos.

Dyno.jpg

I could fiddle with engines on a dyno everyday and be quite happy.

[bobl]

Your dyno results look really good, and seem to fall in line with an accurate dyno. Just for grins I put your engine specs in a modeling program I use. I have an engine dyno and built many engines which I run through this program to compare real world results, so I have a good data base of engine builds to compare. Anyway, it projected your engine at 335 wheel HP and 329 ft. lbs. of torque, which I find pretty amazing to be that close to your actual results. FYI, it showed 394 flywheel HP, 387 ft. lbs of torque, using STD correction factor. Being a data nut, I found this pretty interesting.

Bob

[scottiec]

Your dyno results look really good, and seem to fall in line with an accurate dyno. Just for grins I put your engine specs in a modeling program I use. I have an engine dyno and built many engines which I run through this program to compare real world results, so I have a good data base of engine builds to compare. Anyway, it projected your engine at 335 wheel HP and 329 ft. lbs. of torque, which I find pretty amazing to be that close to your actual results. FYI, it showed 394 flywheel HP, 387 ft. lbs of torque, using STD correction factor. Being a data nut, I found this pretty interesting.

Bob

Bob,

This is wildly interesting. I’m actually surprised it made this much power. I was expecting something closer to 300 wheel. In your experience, what type of drivetrain loss do these cars see? I have a t5 to a solid rear with 3.31s.

[CVOBill]

That's really good numbers Scott. Congrats.

[scottiec]

That's really good numbers Scott. Congrats.

Thanks, Bill!

[TexasAviator]

Great work my friend. Sorry you had to rebuild. I didnt go digging but what caused the need for the rebuild? I handbuilt my engine and plan on getting on a chassis dyno as soon as possible. I still have a lot to do to get my dash together. Its almost there. I cant wait but life is really getting in the way at the moment. Awesome and exciting results.

[bobl]

Bob,

This is wildly interesting. I’m actually surprised it made this much power. I was expecting something closer to 300 wheel. In your experience, what type of drivetrain loss do these cars see? I have a t5 to a solid rear with 3.31s.

I’ve not had the opportunity to dyno an engine, put it in the car and then do a chassis dyno. So drive train loss is pretty elusive. The fact you had your correction data and engine spec is what intrigued me to take a look. Most chassis dyno runs don’t give you that info and their results vary a lot depending on brand of dyno, etc. Engine dyno’s are pretty well repeatable if calibrated correctly and using a good weather station. I modeled your engine to come up with flywheel HP estimates, so I feel pretty comfortable with that figure. The program calculates wheel HP estimates off of those numbers using an internal formula. The fact they agreed with your actual results lends credence to its accuracy. In this case it works out to about 15% drive train loss.

Bob

[scottiec]

Great work my friend. Sorry you had to rebuild. I didnt go digging but what caused the need for the rebuild? I handbuilt my engine and plan on getting on a chassis dyno as soon as possible. I still have a lot to do to get my dash together. Its almost there. I cant wait but life is really getting in the way at the moment. Awesome and exciting results.

Thanks! I had pulled a 47,000 mile explorer motor from the junkyard. It kept pressurizing the cooling system with exhaust gases. After doing head gaskets (and of course bringing the heads to the machine shop) it was still doing the same thing. I am led to believe there is a crack in the block, or the deck of the block is warped (probably unlikely). I will eventually bring it to the machine shop to get tested and find out what it really was.

[scottiec]

I’ve not had the opportunity to dyno an engine, put it in the car and then do a chassis dyno. So drive train loss is pretty elusive. The fact you had your correction data and engine spec is what intrigued me to take a look. Most chassis dyno runs don’t give you that info and their results vary a lot depending on brand of dyno, etc. Engine dyno’s are pretty well repeatable if calibrated correctly and using a good weather station. I modeled your engine to come up with flywheel HP estimates, so I feel pretty comfortable with that figure. The program calculates wheel HP estimates off of those numbers using an internal formula. The fact they agreed with your actual results lends credence to its accuracy. In this case it works out to about 15% drive train loss.

Bob

That is really impressive. Especially because you didn't get all the details regarding combustion chamber size, quench, etc. As far as drivetrain loss, I would think that these cars would have a little less than 15%, but that is not based on anything scientific.

Also, I don't understand why drivetrain loss is done as a percentage. It take a certain amount of ponies to spin the trans, diff, etc. Wouldn't a drive train loss just be constant number for a certain type of set up? Just thinking out loud.

[bobl]

That is really impressive. Especially because you didn't get all the details regarding combustion chamber size, quench, etc. As far as drivetrain loss, I would think that these cars would have a little less than 15%, but that is not based on anything scientific.

Also, I don't understand why drivetrain loss is done as a percentage. It take a certain amount of ponies to spin the trans, diff, etc. Wouldn't a drive train loss just be constant number for a certain type of set up? Just thinking out loud.

That's been debated a lot. My personal explanation is this: The main loss is gear drag going through the trans and differential. As the engine power and rpm increases, the friction loss increases, since the dyno is trying to resist acceleration. Most chassis dynos are inertia that measure acceleration rate, so it's a lot harder to compare. Let's say you've got the car on jack stands with it idling in high gear. There is no load and it is taking very little HP to turn the wheels. If the loss was constant the engine would die since it doesn't produce enough power at idle. Here’s a bit different example. I build high performance boat engines and my dyno works as a propshaft dyno as well as engine dyno. A drive on a boat has 2 gear sets, each at 90 degrees. I’ve done quite a few tests where I dynod the engine, put it in the boat and dynod it again. I’ve done 300 hp engines up to 1000 hp engines. The result is always right at 10% loss ,with mechanical connections using the same dyno so it’s a direct comparison with gear loss being the only variable. Hope this helps some.

Bob

[bobl]

An additional thought is that there are also losses from the tires and slippage on the chassis dyno. That would be the reason that hub dynos always produce a higher Hp than a wheel dyno, all else being equal. The tire losses are a big variable from car to car or dyno to dyno.

[scottiec]

That's been debated a lot. My personal explanation is this: The main loss is gear drag going through the trans and differential. As the engine power and rpm increases, the friction loss increases, since the dyno is trying to resist acceleration. Most chassis dynos are inertia that measure acceleration rate, so it's a lot harder to compare. Let's say you've got the car on jack stands with it idling in high gear. There is no load and it is taking very little HP to turn the wheels. If the loss was constant the engine would die since it doesn't produce enough power at idle. Here’s a bit different example. I build high performance boat engines and my dyno works as a propshaft dyno as well as engine dyno. A drive on a boat has 2 gear sets, each at 90 degrees. I’ve done quite a few tests where I dynod the engine, put it in the boat and dynod it again. I’ve done 300 hp engines up to 1000 hp engines. The result is always right at 10% loss ,with mechanical connections using the same dyno so it’s a direct comparison with gear loss being the only variable. Hope this helps some.

Bob

This makes a lot of sense. I didn't think about the load from the dyno itself.