Perspective on the Civic Si 1.5T engine choice

[CEXT]

If a car had no tachometer, can you tell what rpm an engine revs to? It's all psychological. It's more about how smooth an engine revs as opposed to what rpm it can hit. I guess what people are referring to is the peaky nature of the last gen SI. What's funny is people try to beef up the midrange of the old SI by tuning and lowering the rpm of the VTEC engagement. But when an SI comes from the factory with a beefy midrange, people complain it's not fun.

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[Ryude]

If a car had no tachometer, can you tell what rpm an engine revs to? It's all psychological. It's more about how smooth an engine revs as opposed to what rpm it can hit. I guess what people are referring to is the peaky nature of the last gen SI. What's funny is people try to beef up the midrange of the old SI by tuning and lowering the rpm of the VTEC engagement. But when an SI comes from the factory with a beefy midrange, people complain it's not fun.

Yes ... I had a truck that had a busted tach and it was a stick shift. I knew exactly what RPM it was at just by feel and noise.

 

[serif]

If a car had no tachometer, can you tell what rpm an engine revs to? It's all psychological. It's more about how smooth an engine revs as opposed to what rpm it can hit. I guess what people are referring to is the peaky nature of the last gen SI. What's funny is people try to beef up the midrange of the old SI by tuning and lowering the rpm of the VTEC engagement. But when an SI comes from the factory with a beefy midrange, people complain it's not fun.

It's not psychological at all. I went from an 8G Si to an E92 335i, with a 1200RPM-lower redline and more than double the torque than the K20Z3. Even with the torque I missed the revs. Like a lot of modern turbo engines, the N54 choked up top. Power builds until about 3500, then drops off from about 6000. Now, it was still fun because of all the torque, but it's a different kind of fun. There was no wringing its neck and bouncing off the rev limiter. It was a different character altogether. Getting back into a naturally aspirated Honda (granted a slushbox V6, but still), one of the greatest joys is taking it all the way up to redline, even though it's lower still. But because the redline is lower and it makes power all the way up, I still yearn for more.

The difference in power delivery between a good NA car and a good turbo car is night and day. A good NA engine builds and builds to a crescendo, and a good turbo builds then holds. All the buildup is done by 4000rpm. From there, it's flat. Great for dyno and numbers, but "flat" is an apt description of the feeling, too.

All that said, while I clearly prefer NA, I understand why Honda is going this route I'm hopeful--and it's possible--that they'll be able to tune the 1.5T to feel more like an NA as Porsche has done with the 991.2. Keep the crescendo.

 

[procivic]

8200rpm for the K20z3. Hondata tune takes it to 8600 RPM.

I think Honda could have still made the 1.5T a fun engine to have in the Si. All they had to do was make it rev and make it sound good (7500rpm or more) Instead they tuned it into a "high torque" version of the 1.5T in the base civic. A high torque 1.5T basically means, not fun, not high revving, easy/lazy/cheap way to hit power goals for the Si. Basically the same complaint every Turbo motor gets now in days.

Honda SHOULD have done more to make the Si different from the base civic turbo. They have the knowledge and skills to do it.... Yes everyone is going turbo but that does not mean Honda should build a Si without passion. Look at Porsche. Their new base 911 has a 3.0TT that revs to 7600rpm and feels like a N/A engine. Thats what Honda should have done with the Si. Make it rev and make it fun. Save the lap times for the CTR. Anyway enough ranting for one night....

I totally get your comment, and that was one of my fears as well until I drove our tuned 2017 Civic manual trans. When you put your foot down on the pedal, the real rush of acceleration actually just starts around 4K RPMs and continues until the very top. So, despite the lower RPM it still feels like a top end motor to me. It obviously doesn't have the "scream" of the older high-revving N/A motors, but I feel like the extra acceleration and fuel economy are worth the change. Plus, with an intake, exhaust, and possibly upgrade BOV (diverter valve) I think this 1.5T Civic will sound pretty epic. I'm looking forward to posting some videos once we make all those changes on our shop car.

 

[Design]

8200rpm for the K20z3. Hondata tune takes it to 8600 RPM.

I think Honda could have still made the 1.5T a fun engine to have in the Si. All they had to do was make it rev and make it sound good (7500rpm or more) Instead they tuned it into a "high torque" version of the 1.5T in the base civic. A high torque 1.5T basically means, not fun, not high revving, easy/lazy/cheap way to hit power goals for the Si. Basically the same complaint every Turbo motor gets now in days.

Honda SHOULD have done more to make the Si different from the base civic turbo. They have the knowledge and skills to do it.... Yes everyone is going turbo but that does not mean Honda should build a Si without passion. Look at Porsche. Their new base 911 has a 3.0TT that revs to 7600rpm and feels like a N/A engine. Thats what Honda should have done with the Si. Make it rev and make it fun. Save the lap times for the CTR. Anyway enough ranting for one night....

As a long term owner of both iterations, I actually think small displacement/small turbo powertrains are more fun for daily use. My one gripe with this approach (which Honda has minimized) is that power tends to fade in the upper range. More noticeable once a tune exploits the mid range output.

Sure, they could go with a more expensive approach like variable geometry. But I'm willing to withhold judgement until I drive the Si.

 

[Ryude]

Well it's pretty hard to design a turbocharged system (while keeping costs in check) that will satisfy low end torque for everyday driving while also having great top end.

Sacrifice either one and you end up with a lot of pissed off customers. That's why generally the turbo is sized so that it spools up around 1500-2000 RPM. A turbocharger has what is called an efficiency island. Too little air and it doesn't spool, too much and it can't expel it fast enough. So as long as turbocharging is the trend, I wouldn't expect to see high RPMs making a come back.

 

[18k]

^^ that's similar to some arguments for the rotary engine -- and Mazda's and others' eventual (and recurring) decisions to drop it. If you ("you" meaning "one", "a company", etc.) can do XYZ better, the value of holding on to the old (not-as-good) way of doing XYZ becomes questionable, at least from any sort of practical perspective. Unless we're talking about something with a historical/cultural value, or something along those lines.

Yes! That's exactly it! The rotary, higher revs, and n/a don't make much sense today. But I know some of us, still want that option.
Also on a side note, yeah none of the new si were as crazy high as the older ones, or the mighty b series, but still different enough compared to any non Honda.

 

[Stock_07]

The rotary engine went out primarily due to emissions. Its in the design for the engine to take oil plus they never lasted that many miles.

 

[Aero2001]

It's not psychological at all. I went from an 8G Si to an E92 335i, with a 1200RPM-lower redline and more than double the torque than the K20Z3. Even with the torque I missed the revs. Like a lot of modern turbo engines, the N54 choked up top. Power builds until about 3500, then drops off from about 6000. Now, it was still fun because of all the torque, but it's a different kind of fun. There was no wringing its neck and bouncing off the rev limiter. It was a different character altogether. Getting back into a naturally aspirated Honda (granted a slushbox V6, but still), one of the greatest joys is taking it all the way up to redline, even though it's lower still. But because the redline is lower and it makes power all the way up, I still yearn for more.

The difference in power delivery between a good NA car and a good turbo car is night and day. A good NA engine builds and builds to a crescendo, and a good turbo builds then holds. All the buildup is done by 4000rpm. From there, it's flat. Great for dyno and numbers, but "flat" is an apt description of the feeling, too.

I know what you mean. I went from a 2001 SAAB 9-5 Aero to a 2010 TSX (both manual trans), and it was a huge change. They're both fantastic, but in different ways as you said. I've missed the SAAB's mighty turbo punch, but I also know if (when) I go back to a turbo, I'll miss the screaming VTEC crescendo from 5,000 to 7,000 rpm. For years, I couldn't figure out which I prefer, but I've realized it depends on the driving conditions. On the highway, I'll take the turbo torque any day, all the time, but everywhere else I like the NA VTEC power delivery.

Newer turbos, however, have better power delivery characteristics than the old SAABs, so on balance I'll probably prefer a modern turbo to my TSX's motor. I've driven a few Focus ST's, for example, and it's fantastic. I hope the Civic Si will combine turbo torque with at least some traditional high-rpm Honda goodness.

 

[Ryude]

Aside from feeling, flat torque curve is way better for performance.

 

[oldman]

I had a chance to actually look at a Honda 1.5T engine parts. Looking at the need (not wants) and customer wants. It looks like IMO that the block can be bored to 76mm and the stroke to 97mm which would yield a 1760cc engine. I'd speculate 220 HP / 210 HP would be doable with properly designed supporting parts (cams, turbo, exhaust size, intake size, intake manifold). Still a tiny engine but well within reason.

The stock Honda engine is 73mm bore x 89.4mm stroke or 1497 CC.

A stroke to 99mm would yield 1657cc or 1.7 liter. 210 HP / 210 torque

 

[oldman]

Well it's pretty hard to design a turbocharged system (while keeping costs in check) that will satisfy low end torque for everyday driving while also having great top end.

Sacrifice either one and you end up with a lot of pissed off customers. That's why generally the turbo is sized so that it spools up around 1500-2000 RPM. A turbocharger has what is called an efficiency island. Too little air and it doesn't spool, too much and it can't expel it fast enough. So as long as turbocharging is the trend, I wouldn't expect to see high RPMs making a come back.

word...

not that the primary island is below one bar 14.7 PSI... it starts getting hot really fast after that.

 

[Ryude]

TD03 can be upgraded to TD04 fairly easy. You can even port the compressor housing and upgrade the compressor wheel. Would shift the boost island right about 500 RPM.

 

[Canndo]

SI was not suppose to be a mpg car. I have always thought Honda cheated the car. This 2017-2018 win ever the car comes out. The car should have no less then 250 whp. Remember the other car makers are going this root also with there cars in 2017-2018. Check around. Honda has left the SI before. Do not get me wrong about Honda , I like them. I got 2016 1.5T brand new for the mpg not hp, it will never be a racer. The type R that japan has, it should of been here a long time ago. A friend of mine got Toyota Supra at a whopping $48,000.00 from C.A. And three years later after that, he got 893whp and its turns 9,600 rpm, at a cost of $10,000.00 more or less. High 8s-9in the 1/4 at bests. The car kicks it wheel out sideways in 3rd gear at about 95mph. Add it up. I got a AWD Evo . A lot of other people have said this in other words. BMW,FORD,SUPAU,MITSUBISHI,TOYOTA,VW.INFINITI,HYUNDAI,SUBARU,MERCEDES,PORSCHE, . Honda owners have said this before ,STEP THE H-LL UP OR MOVE OF SIDE . 2010 CIVIC 140HP $24,515.00, 2014 CIVIC 143HP $25,030.00. 2016 CIVIC 174HP $27,335.00, 2017 CIVIC 180HP $29,876.00.??????????????? AND INFINITI. I wonder what SI will cost? And RRRRR? If I have missed this mark , I am sorry.

 

[tacthecat]

SI was not suppose to be a mpg car. I have always thought Honda cheated the car. This 2017-2018 win ever the car comes out. The car should have no less then 250 whp. Remember the other car makers are going this root also with there cars in 2017-2018. Check around. Honda has left the SI before. Do not get me wrong about Honda , I like them. I got 2016 1.5T brand new for the mpg not hp, it will never be a racer. The type R that japan has, it should of been here a long time ago. A friend of mine got Toyota Supra at a whopping $48,000.00 from C.A. And three years later after that, he got 893whp and its turns 9,600 rpm, at a cost of $10,000.00 more or less. High 8s-9in the 1/4 at bests. The car kicks it wheel out sideways in 3rd gear at about 95mph. Add it up. I got a AWD Evo . A lot of other people have said this in other words. BMW,FORD,SUPAU,MITSUBISHI,TOYOTA,VW.INFINITI,HYUNDAI,SUBARU,MERCEDES,PORSCHE, . Honda owners have said this before ,STEP THE H-LL UP OR MOVE OF SIDE . 2010 CIVIC 140HP $24,515.00, 2014 CIVIC 143HP $25,030.00. 2016 CIVIC 174HP $27,335.00, 2017 CIVIC 180HP $29,876.00.??????????????? AND INFINITI. I wonder what SI will cost? And RRRRR? If I have missed this mark , I am sorry.

You did - we bought our "base" '12 Si Sedan (201 HP) for $21,970. Expect '17 Si to be under $25k, the CTR about $32k in "base" trim.
To each their own - Then there's the HellCat or the Demon!!!

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