# Direct drive SBC

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#### MARCVINI

##### Well-Known Member
Right, and I over-estimated some of the components: the valley cover can weigh half as much because an aluminum intake from Edelbrock weighs 21lb, the motor plate could be lighter as well, and the cam drive chain and sprockets won't weigh 10lb either, so thats 27lb that doesn't need to be included in the estimate. Also, you only really need short stacks for the exhaust, I did include the alternator, and a starter can be light in weight, and the wiring harness is not that heavy either. We could go back and forth, you adding weight and me taking it back off, a radiator will weigh more, like 20lb possibly, and a mount will weigh some more, especially if it's badly designed but it could also be just as light if well designed, lets throw in a really badly made fiberglass cowling that weighs 60 or 70lbs :lick: (what the heck). The point is that a well designed redrive can greatly improve the power to weight ratio of any engine and make an iron block engine competitive with some of the older lycons for far less money - not to quibble about the exact weight that can vary quite a bit depending how well the components are designed...
The weight devil lies on the details...:gig:

Cheers.

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#### Autodidact

##### Well-Known Member
The weight devil lies on the details...:gig:

Cheers.
Now that I must agree with.

#### blainepga

##### Well-Known Member
Depending on models and accessories O-360s weigh around 310-325 lbs. ready to run, including exhaust. IO-360s around 325-345 lbs.

Any engine still needs the prop and mount.
The combination I am using will produce 260 hp and 250 ft lbs and weigh about 425 lbs fwf. My PSRU weighs 55 lbs. The complete engine with supercharger weighs 314 lbs. It's a GM Ecotec LSJ 4 cylindar 2.0 Liter (or in american 120 cu in). It is designed to to get the majority of torque and hp between 4K and 5k. These weights are right inline with the io-360's with better hp and fuel economy.

Blaine Anderson

#### Toobuilder

##### Well-Known Member
HBA Supporter
Log Member
... These weights are right inline with the io-360's with better hp and fuel economy...
You might want to temper your expectations concerning fuel economy. The mechanical conversion of fuel to heat to mechanical output is pretty straightforward. In short, HP "costs" a certain fuel burn, regardless of the manufacturers name on the valve cover. Yes, modern automotive engines are exceptionally efficient, but the fact of the matter remains that a Lycoming is also pretty good at turning fuel into thrust - particularly if run LOP like a modern car.

#### MARCVINI

##### Well-Known Member
The combination I am using will produce 260 hp and 250 ft lbs and weigh about 425 lbs fwf. My PSRU weighs 55 lbs. The complete engine with supercharger weighs 314 lbs. It's a GM Ecotec LSJ 4 cylindar 2.0 Liter (or in american 120 cu in). It is designed to to get the majority of torque and hp between 4K and 5k. These weights are right inline with the io-360's with better hp and fuel economy.

Blaine Anderson
Given your engine oficial dyno charts, looks promissing. What is your PSRU´s gear ratio? Already have any idea on cooling system?

Marcvini FORGET THIS MESSAGE. BETTER ONE AHEAD.

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#### dino

##### Well-Known Member
HBA Supporter
Ecotec promises better rewards if you're up to the greater complexity. Fuel burn (spc) depends on many things other than output. For instance, an ECU controlled high pressure direct injection engine would have a significantly lower spc than a similar carburetor engine.

dino

#### stol

##### Well-Known Member
The combination I am using will produce 260 hp and 250 ft lbs and weigh about 425 lbs fwf. My PSRU weighs 55 lbs. The complete engine with supercharger weighs 314 lbs. It's a GM Ecotec LSJ 4 cylindar 2.0 Liter (or in american 120 cu in). It is designed to to get the majority of torque and hp between 4K and 5k. These weights are right inline with the io-360's with better hp and fuel economy.

Blaine Anderson
There "might" be durability issues at that sustained power level... IMHO..

#### MARCVINI

##### Well-Known Member
The combination I am using will produce 260 hp and 250 ft lbs and weigh about 425 lbs fwf. My PSRU weighs 55 lbs. The complete engine with supercharger weighs 314 lbs. It's a GM Ecotec LSJ 4 cylindar 2.0 Liter (or in american 120 cu in). It is designed to to get the majority of torque and hp between 4K and 5k. These weights are right inline with the io-360's with better hp and fuel economy.

Blaine Anderson
Hey, there is something wrong here. This is the oficial dyno chart for the LSJ4, wich, by the way, I had been studying long ago:

If you really want to squeeze 260hp/250 ft lb of it, you will have to boost the hell out of it, my friend. YOU WILL REALLY HAVE RELIABILITY ISSUES.

An LNF seems more apropriate for the power you intend to have:

Would you explain a little better how you are going to reach those power figures you are looking for for your prospective LSJ based powerplat?

By the way: I still wanna know how you are going to work your cooling system out?

Tailwinds.

#### rv6ejguy

##### Well-Known Member
HBA Supporter
The combination I am using will produce 260 hp and 250 ft lbs and weigh about 425 lbs fwf. My PSRU weighs 55 lbs. The complete engine with supercharger weighs 314 lbs. It's a GM Ecotec LSJ 4 cylindar 2.0 Liter (or in american 120 cu in). It is designed to to get the majority of torque and hp between 4K and 5k. These weights are right inline with the io-360's with better hp and fuel economy.

Blaine Anderson

I like the LSJ engine and you can get some amazing hp from it with some trick pieces (like 1400hp). A few years ago, we looked at doing a FF package with this engine as a basis and the power to weight ratios with a turbo look pretty good. For aircraft, using essentially stock crate engines, 200hp for takeoff would not require much boost or reduce reliability to any great degree. The stock engines already have some pretty good parts inside.

The supercharger was going to be tossed in favor of a turbo which is lighter, more efficient, reliable and easier to control boost at various altitudes.

We've done pretty similar stuff with the EJ257 Subarus and they are a bit lighter and there are more gearbox choices out there too. A couple of RV7s with these showed very impressive speeds (210-220 KTAS) and equal fuel economy to Lycomings running far less than factory boost levels.

Lots of ways to skin the 200-230hp cat in the automotive engine world. You can do the whole engine for $5K but you need another$4K for the gearbox...

E

#### ekimneirbo

Flex plates- I'll once again point to the Corvette unit which is little more than an automatic transmission flexplate with a splined hub bolted to the center. They are very low inertia and they don't seem to crack.

camshafts- I'll agree that you will want a grind that is targeting 25-3000 RPM as an upper RPM limit, but how much gain can you get from a "perfect" grind over one found in say, that little 5.3 Vortec stump puller? With the roller profiles and port geometry of the LS series, even the "hot" engines have a ton of low end grunt. My LS-3 in the Corvette pulls down to 1000 RPM without complaint. Yes, you could do better with a custom grind, but I seriously doubt you are going to find any "magic" cam that's going to make or break a DD installation. We're talking about 250 -300 HP here.... There's just not that much margin to play with.

Reply: I think a 415 cu in version will probably produce good hp with a stock cam, but since GM makes several cams for the LS engines, the numbers I posted give me an idea where to start looking. If purchasing a new cam from GM, then it would be just as well to purchase an aftermarket cam. I think the biggest thing here is trying to get as much lift as possible with a short duration cam. Most short duration cams don't have lots of lift. Different ratio rocker arms might also help the situation.....but I do agree that a stock GM truck cam should provide reasonable results.

I've said it before and I still return to one universal truth: There's no replacement for displacement. Any money spent on a custom DD engine should go into the longest stroke you can afford. I think most of the performance issues would go away with a 510 inch LS, but that short block is about $14k... You're up in aircraft engine territory at that point. Reply: I agree whole heartedly, but think that 415 cu in should easily be able to provide the same or more hp/torque as a 360/390 cu in aero engine with antiquated technology, and probably as much as a 540 if properly done. I think a 415 could be assembled and a direct drive coupled to it for$10k or less.......but if it did exceed that figure it would still be way less than a new aero engine. $30k or more for a 360 engine or your wife and first borne son for something bigger. To me if there is a substitute for displacement, it probably will be a turbo four cyl. I haven't heard anything promising about rotary engines lately. #### Toobuilder ##### Well-Known Member HBA Supporter Log Member I agree that a purpose built DD LSx will crush a 4 banger Lycoming in HP and cost, but unfortunately, I think it will do it literally (weight) as well. As long as the standard is "power/weight", I think the 4 banger Lycomings will win. And this is why I've selected the 540 as the target. The power scales much more favorably for the V8 above the 300 HP level. #### stol ##### Well-Known Member I agree that a purpose built DD LSx will crush a 4 banger Lycoming in HP and cost, but unfortunately, I think it will do it literally (weight) as well. As long as the standard is "power/weight", I think the 4 banger Lycomings will win. And this is why I've selected the 540 as the target. The power scales much more favorably for the V8 above the 300 HP level. Agreed 100%... #### Toobuilder ##### Well-Known Member HBA Supporter Log Member Just as a comparison- I have data for a 500 inch LS drag race engine that shows 600 ft pounds and 514 HP at a leisurely 4500 RPM. Keep in mind that this is tuned for a much higher RPM peak of 717 HP at 6500. This engine will not weigh much more than a few pounds more than any LS series engine, but how much will a 500 HP Lycoming weigh? Anybody run a TSIO 720 across the scales lately? #### stol ##### Well-Known Member Just as a comparison- I have data for a 500 inch LS drag race engine that shows 600 ft pounds and 514 HP at a leisurely 4500 RPM. Keep in mind that this is tuned for a much higher RPM peak of 717 HP at 6500. This engine will not weigh much more than a few pounds more than any LS series engine, but how much will a 500 HP Lycoming weigh? Anybody run a TSIO 720 across the scales lately? I would take a safe guess it is well over 700 lbs full dressed... #### Vigilant1 ##### Well-Known Member Lifetime Supporter I haven't heard anything promising about rotary engines lately. This is a thread (primarily) about small block piston engines, but the 160-250 HP zone is where the standard and "peripheral-ported" NA 13B and Renesis engines are well understood and reliably hauling airplanes around every day. The only requirement for anything out of the ordinary is if a total FWF weight (incl rad and coolant) of less than about 300 lbs is needed (to get lighter weights requires aftermarket aluminum end and mid-plates, which saves quite a bit of weight but adds quite a bit of cost). With PSRU, rad, coolant, etc, the 13B is roughly equivalent in >true< all-up weight to an O-360. Last edited: #### blainepga ##### Well-Known Member There "might" be durability issues at that sustained power level... IMHO.. Considering that rally cars run flat out with 400hp and drag engines of about 1400hp, the durability issues with this engine have been answered. Blaine Last edited: #### blainepga ##### Well-Known Member Hey, there is something wrong here. This is the oficial dyno chart for the LSJ4, wich, by the way, I had been studying long ago: View attachment 31579 If you really want to squeeze 260hp/250 ft lb of it, you will have to boost the hell out of it, my friend. YOU WILL REALLY HAVE RELIABILITY ISSUES. An LNF seems more apropriate for the power you intend to have: View attachment 31580 Would you explain a little better how you are going to reach those power figures you are looking for for your prospective LSJ based powerplat? By the way: I still wanna know how you are going to work your cooling system out? Tailwinds. The cooling system and all other issues will be covered in my "Auto Engine to Aircraft" post on this site. By the way, the turbo version of this engine has 260hp stock as your graph shows. Although the Cadilac version has 272hp. Blaine Last edited: #### blainepga ##### Well-Known Member I like the LSJ engine and you can get some amazing hp from it with some trick pieces (like 1400hp). A few years ago, we looked at doing a FF package with this engine as a basis and the power to weight ratios with a turbo look pretty good. For aircraft, using essentially stock crate engines, 200hp for takeoff would not require much boost or reduce reliability to any great degree. The stock engines already have some pretty good parts inside. The supercharger was going to be tossed in favor of a turbo which is lighter, more efficient, reliable and easier to control boost at various altitudes. We've done pretty similar stuff with the EJ257 Subarus and they are a bit lighter and there are more gearbox choices out there too. A couple of RV7s with these showed very impressive speeds (210-220 KTAS) and equal fuel economy to Lycomings running far less than factory boost levels. Lots of ways to skin the 200-230hp cat in the automotive engine world. You can do the whole engine for$5K but you need another $4K for the gearbox... How about$2100 for the gear box. It normally bolts to the big/small/v6 chevy pattern. I am in the process of building an adapter plate to mate the PSRU to the LSJ engine. This PSRU has a 2/1 ratio. They have other ratios available.

In drag racing I have worked with both superchargers and turbos. This motor has a supercharger. I thought it would fun. The dyno will tell the tale before it gets into the air. To start with I am going to try several smaller diameter pulleys on the blower to get more boost at the lower rpm range. For this application the stock injectors and fuel rail are ok.

Blaine

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#### Toobuilder

##### Well-Known Member
HBA Supporter
Log Member
I would take a safe guess it is well over 700 lbs full dressed...
I'd guess that too. Which means that if you needed 450+ HP, an automotive derived V8 with even the heaviest PSRU around would meet and eventually surpass the power/weight of the big bore aircraft engines.

So looking at it another way, looking strictly at power/weight, a IO-720 replacement should be "easy"; a 540 replacement is "possible"; while the 360 is going to be tough to replace with a V-8.

#### MARCVINI

##### Well-Known Member
Agreed 100%...
I also agree. But a criterious aproach SBC/SBF DD wise could make the weight diference manageable. Stol´s success story is the living (and flying...) proof that engine weight diference can be managed.

Markvini

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