I saw a new thread of swap from C series to J series, for what i've read both are V6 vtech Doch engines but what are the major difference between one and other?? Just curiosity.
Difference between C and J series
- Thread starter Venom2049
- Start date
Isn't j series shoc
I think that's D series
I think J is SOHC. It is also cheaper, less well-made, without advances like titanium connecting rods. It's a 20 y.o. supercar engine vs a modern sedan
J and d series are shoc . D is 4 banger, j is 6 haha
I think the biggest difference is that the J-series engines are more compact. They're 60 degree V6s instead of the 90 degrees in the C-series engines. This makes them more versatile so they can be fit into a wider range of vehicles, but the narrower angle also keeps SOHC.
Can they rev as high as the nsx like 8k rpm or since they are sohc they can't??
Just look at the picture he has, each head has one cam gear... Sohc
I don't know anything about engines, idk if the cams affect on the revving attributes of the car or not
One of the benefits of DOHC is that by having a camshaft for all the exhaust valves, and another camshaft for all the intake valves, you keep the mechanism for the cams to push the valves open nice and simple and most of all, lightweight. The lightweight part means you can rev higher and the cam follower/spring/rocker will have low inertia so they can follow the profile of the cam better. You can think of it as a car going over the crest of a hill, where the cam follower is the car and the hill is the lobe on the cam. If you rev too high, the follower will jump off the top of the lobe and skip over the "downhill" part. This is called valve float, and it damages the valvetrain because the valve is slamming shut. If the follower and valves are lighter, then the spring can keep the follower pressing down on even on the downhill part of the lobe. The worst case is a pushrod engine, where the cam is in the "V" between the cylinder banks, and there is a very long distance from there to the head. You need a heavy pushrod to "push" the valve from way down below, and that means a lot of inertia, which means the engine cannot rev as high.
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The C-series is a 90-degree V6 design. It was the original V6 invented by Honda for its passenger cars. Early versions were SOHC with no VTEC at all and used in the Legend, Vigor and Accord. The version for the NSX is a DOHC with VTEC and was designed to operate at 8000+ rpm.
The J-series is Honda's current V6 design and was intended to improve on the C-series. It is a 60-degree V6 SOHC design with VTEC on the intake side only. The J-series was designed from the beginning to be smaller, smoother and more efficient than the C-series. It uses a special, smaller crankshaft to reduce weight and a more compact, advanced version of VTEC compared to the C-series. The J-series was designed from the beginning to power all of Honda's passenger cars, so it is not really a high performance engine by design. Instead, focus was on low and mid-range torque plus fuel economy, which is important for the everyday driver. The J started out as a 3.0 liter and has been continually enlarged to 3.2, 3.5 and finally 3.7 liters. The 3.7 liter J37A4 is the most "performance" oriented version of the engine so far. It is special because while it is still only SOHC, it has VTEC on both the intake and exhaust sides. It is used on the Acura ZDX and the SH-AWD trim version of the Acura TL. Even so, it still is a low-rpm engine compared to the NSX. The J-series never was designed to spin above 7000 rpm, so some serious internal work, including a new valvetrain and ECU, would be required to get it to NSX-level.
Acura may already be doing this work for us, however. The new NSX engine is said to be a J-series adapted for high rpm and integrated with the hybrid SH-AWD system. We have to wait and see.
The J-series is Honda's current V6 design and was intended to improve on the C-series. It is a 60-degree V6 SOHC design with VTEC on the intake side only. The J-series was designed from the beginning to be smaller, smoother and more efficient than the C-series. It uses a special, smaller crankshaft to reduce weight and a more compact, advanced version of VTEC compared to the C-series. The J-series was designed from the beginning to power all of Honda's passenger cars, so it is not really a high performance engine by design. Instead, focus was on low and mid-range torque plus fuel economy, which is important for the everyday driver. The J started out as a 3.0 liter and has been continually enlarged to 3.2, 3.5 and finally 3.7 liters. The 3.7 liter J37A4 is the most "performance" oriented version of the engine so far. It is special because while it is still only SOHC, it has VTEC on both the intake and exhaust sides. It is used on the Acura ZDX and the SH-AWD trim version of the Acura TL. Even so, it still is a low-rpm engine compared to the NSX. The J-series never was designed to spin above 7000 rpm, so some serious internal work, including a new valvetrain and ECU, would be required to get it to NSX-level.
Acura may already be doing this work for us, however. The new NSX engine is said to be a J-series adapted for high rpm and integrated with the hybrid SH-AWD system. We have to wait and see.
So what is the advantage of having a high revving engine like the 3.0 or 3.2 instead of a "high performance" J series engine??
The exotic sound and operation as well as an optimal power curve for high performance driving. The J's tend to fall off after 6000 rpm. It's all in the cams.
What's an optimal power curve?? This forum is better than wiki lol
That is a trick question and I am not sure the NSX engine would fit that bill. Also, exacerbated by the the weird 5-speed gearing.
Why wouldn't it fit on that class? I thought the 5 speed tranny was a good one specially for fi? Is it not true?
Great answer...assuming everything is correct :smile: and I have no reason to think it wouldn't be.
While we are talking about why engines can and can't spin at high RPM, it might be worth noting that the structure of the block is also crucial and explains why it is hard to make an engine spin higher than it is meant to.
When the engine is running at high rpm, there are tremendous forces going on inside. You are accelerating the pistons up and down at amazing speeds with big G forces, reversing direction instantly, AND you are exploding fuel and transmitting huge force through the piston and connecting rods, all at the same time. And they alternate tension and compression rapidly many times per second. With all these forces, you are going to want all the parts to stay in EXACTLY in alignment. You can imagine if you had a running engine and you moved the crankshaft a tiny bit to the side so that it didn't line up with the direction of the pistons. The bearings would grind and seize, and the whole thing would blow up. Keeping everything exactly straight is the job of the block, and it's difficult to make sure it doesn't flex as you sweep through the rpm range. You can see in high performance engines that they add more visible webbing and structure to make sure everything stays straight.
A common approach to increase RPM is to add a structural brace to the block. It can be external, like an Integra Type R's block brace, or it can be inside the crankcase (I think Porsche does this as does Honda). However, these are just band-aids and it is best to engineer this in from the start.
When the engine is running at high rpm, there are tremendous forces going on inside. You are accelerating the pistons up and down at amazing speeds with big G forces, reversing direction instantly, AND you are exploding fuel and transmitting huge force through the piston and connecting rods, all at the same time. And they alternate tension and compression rapidly many times per second. With all these forces, you are going to want all the parts to stay in EXACTLY in alignment. You can imagine if you had a running engine and you moved the crankshaft a tiny bit to the side so that it didn't line up with the direction of the pistons. The bearings would grind and seize, and the whole thing would blow up. Keeping everything exactly straight is the job of the block, and it's difficult to make sure it doesn't flex as you sweep through the rpm range. You can see in high performance engines that they add more visible webbing and structure to make sure everything stays straight.
A common approach to increase RPM is to add a structural brace to the block. It can be external, like an Integra Type R's block brace, or it can be inside the crankcase (I think Porsche does this as does Honda). However, these are just band-aids and it is best to engineer this in from the start.
Nico,
Think about the major if not only benefits of high revving engines. The more RPM range you have, the less time you have to spend shifting gears (assuming a decent gearing of the transmission). You can make power longer before you have to shift. Transmission gearing plays a major role in all of this. The C is and was a great motor designed for a certain purpose. The J is another great motor offering a different solution to common problems: Cost, Parts availability, etc.. We all know the benefits of weight savings in our cars. The J is much lighter. So the J may not rev as high.. so what. 7000 vs 8500. If you want to build a J for your NSX, you can always go back to the C because you will still have it. Put a large turbo on a built J and you wont need high RPMs to have fun...trust me. The torque will win you over. The sound may not be as "exotic", but the car will be fast as nuts!
Think about the major if not only benefits of high revving engines. The more RPM range you have, the less time you have to spend shifting gears (assuming a decent gearing of the transmission). You can make power longer before you have to shift. Transmission gearing plays a major role in all of this. The C is and was a great motor designed for a certain purpose. The J is another great motor offering a different solution to common problems: Cost, Parts availability, etc.. We all know the benefits of weight savings in our cars. The J is much lighter. So the J may not rev as high.. so what. 7000 vs 8500. If you want to build a J for your NSX, you can always go back to the C because you will still have it. Put a large turbo on a built J and you wont need high RPMs to have fun...trust me. The torque will win you over. The sound may not be as "exotic", but the car will be fast as nuts!
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Oh really?? Sell your engine and lets build a J series
I would just keep my motor! Im not afraid to build a J, more concerned about fabbing the motor mounts and getting the axles right...things like that.
Well let's wait for the build to be done and then see what he comes up with
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