I'm not well educated with 8th gen Si's, but I think it's worth considering that the 9th gens have more torque. This may be a strong factor for track driving, I'm not sure.

I have 3 20-minute track sessions under my belt, all done on the same day. It's amazing how much each session I improved my times and ability not to be passed by other drivers. It was a 2 mile closed track, and there were 30 novice cars driving all at once.

My car is supercharged, so my experience with acceleration would be different than yours. That being said, either platform would probably be negligible (NA), given similar mods.

The most important factors for track days are tires, suspension, brakes, tune, and bolt-ons. (in that order).

I have another track day coming up in a month, and plan on pulling the passenger seat and rear seat-backs for decreased weight.

 

The cars are nearly identical. The biggest chassis difference between them is probably the wheelbase, the 8th gen's is slightly longer than the 9th. Both cars will respond similarly to bolt ons, but the 9th gen will have better corner exit power delivery because of its broader powerband. The 8th gen has a tighter steering rack and better pedal placement.

 

So on this forum I think there will be a bias towards the 9ths, and if you go on the 8th gen forum, there will be a bias towards 8th gens.

So I'll tell you this, my honest opinion, the 8th gen si is probably the last TRUE Honda civic si ever made. A FWD, high revving 8k redline doesn't make jack shit power until vtec kicks, and also a lightweight car, which essentially is what an Si should be. The K20 is a beautiful engine and I mean beaaaaaaaautiful, you will want to stay up in the high RPMS simply just to hear the vtec engagement over and over again because it's like music to your ears lol. It's a race motor just waiting to be modified, like it wants you to beat on it, it wants you to mod it, because it's just such a tune-able engine.

The 9th gens on the other hand is a far better daily with it's updated driver oriented interior, back up camera, side camera, heated seats etc., though many people consider the k24z7 to be a economy engine for whatever reason. OH and there's no annoying 2nd to 3rd gear grind which is notorious in the 8th gens. You still get a LSD stock and a huge aftermarket support, and the option to swap a RBC intake manifold to revive that 8K redline.

If you go on reddit, or watch reviews on youtube, a lot of car reviewers and even Honda enthusiasts will say the same thing, and usually always ends with the conclusion that the 8ths are better for track, whilst the 9ths are better dailies. However, the 9ths are capable of making pretty damn good power, but the 8ths are more preferred for bolt-ons, as apparently bolt-on v bolt-on, an 8th will beat a 9th. Now whether that's true or not, I think both cars are very close together when it comes to a straight line race, but that just shows how good the 8ths are, as a 2009 Si with 197hp/139tq can keep up with a 2014 Si with 205/174tq. Why is that? Well the 8ths are lighter, and make its peak torque in the high rpms where when racing, you'll be up in the high rpms most of the time. The 9ths make peak torque around 4-5k rpms and it dips after that. Side note: Now these are just what I've read awhile ago from other users around other forms so my numbers may not be entirely accurate, but the K20 is no joke that's for sure.

Would I choose an 8th over my 9th? Helllll naaaah, I prefer the looks of the 9th. especially the sedan and the mid range torque really makes daily driving easier. I believe the 9th fits your needs. You want a good daily, aftermarket friendly, good gains from bolt-ons, forced induction kits readily available, and huge modding community, the 9th fits your needs. If you plan on gutting a car, want to spend less on the car overall, then get the 8th. It's far cheaper because it's older, and you'll likely find more used parts floating around.

 

What kevvo said. 8ths are more fun to drive spirited with that k20. 9th is nicer to daily because of torque.

 

And then we have the 10th gen, where a non-Si hatch sport would be a better fit for me than the Si due to the fancy electronic suspension that would be difficult to mod (also the horrible exhaust on the Si). Decisions, decisions ...... let me start test driving.

 

If you're looking for a track car, the 10th gen chassis blows away the 8th&9th gen. The problem with the 10th gen is the motor, I wouldnt trust it on a track day.

 

I've driven both. My friend and I would swap cars for a week just to see the difference and drive something different periodically. IMO I would rather have an 8th gen for track days. Daily driving wise, both the 8th and 9th gens have small differences that you'd only pick up on if you driven both cars back and forth. 8th gen is definitely fun to drive because of the 8k rev limit and intake/exhaust vtec cams. The 9th gen is a bit more refined and with the updated 'creature features' definitely make it a better DD.

Only thing you got to worry about the 8th gen is the dreaded 3rd gear grind w/ spirited driving. Unfortunately can't say the same with my 9th gen because I get locked out of 2nd gear during spirited driving and quick shifting. *Dealership replaced my syncros but still happens on occasion.*

I love my 9th gen but for some reason, for me at least, the 8th gen feels a bit more 'raw' compared to the 9th gen which is why I always liked the 8th gen.

 

Well put. 8th gen feels way more raw but in a good way.

 

The 10th gen chassis blows away the 9th gen's? In theory the next generation of a car should be better, but as a track car that may not be the case. Do we know the extent of the electronic nannies on the 10th gen and how much the driver can turn them off? And we all have heard of the overheating issues so far with the turbo. As a DD driven car the 10th gen should be better in almost every way.

But until the 10th gen has the level of aftermarket support and testing the 8th or 9th gen has, reliability would seem to be with the older cars. I think we all look forward to seeing what can be done with the 10th gen as personally I always like new cars as opposed to older cars.

 

The 10th gen chassis blows away the 9th gen's? In theory the next generation of a car should be better, but as a track car that may not be the case. Do we know the extent of the electronic nannies on the 10th gen and how much the driver can turn them off? And we all have heard of the overheating issues so far with the turbo. As a DD driven car the 10th gen should be better in almost every way.

But until the 10th gen has the level of aftermarket support and testing the 8th or 9th gen has, reliability would seem to be with the older cars. I think we all look forward to seeing what can be done with the 10th gen as personally I always like new cars as opposed to older cars.

It absolutely is the case. Compare the track times between the 10th gen and its predecessors. C&D has hot lapped the last 3 generations of civic si at VIR Grand West, at 3:24.1 the 9th gen shaves 2 seconds off the 8th gen's 3:26.5 time. The 10th gen does an insanely fast 3:14.6, faster than an S2000 CR. Since the 10th gen doesnt pick up any acceleration gains from its predecessors, almost all of that 10 seconds is picked up in handling and braking.

 

So, a test 5 and 10 years apart makes for a absolute answer? While we could easily go with this information, was the driver the same, the weather the same, and was the course surface the same? A stock 8th gen had 215/45 tires I believe, a 2012 9th gen had 215/45 tires, and the 10th gen has 235/40 tires. That difference in tire width will make a huge difference as will the OEM tire choice, and we haven't even brought up the OEM brake size.

So in theory the same driver in a brand new 8th gen, 9th gen and a 10th gen Si, the 10th gen would be the fastest, no argument from me. For one lap that is. How much would the 10th gen slow down due to overheating in a 20 minute session? And for DD the 10th gen would be in another class.

Now, let's take a track setup for each of these cars and run them and you may find a completely different result or much closer times. My guess is we could easily fit 255/40/18 on the 10th gen and 245/40/17 on the 8th and 9th gen so we are getting very close to the same tire width. For the racer the 17" tires are going to less expensive than the 18's and the setup will be lighter. And we know that the cars weigh the same as the 10th gen specs out lighter but that is due to not having a spare tire. With my STX autocross setup, my 2015 9th gen Si weighs in at 2740 lbs which is almost 200 lbs lighter than stock and will be under 2700 soon.

The future looks bright with the new Si as it looks like the overheating issue may be solved and the tuning is looking good. It should be a fun car to track or autocross and for DD it should be very nice.

 

Yeah, C&D's lightning lap at VIR is the most reliable benchmark you can find. These tests are recorded and you can see how much more composed the 10th gen is. 20 MM in tire width isn't going to create a 10 second gap. The type R upper control arms, solid bushings and a much more sophisticated structure all contribute more than the 20 mm wider tires.

I agree with you on the motor. Even if cooling is sufficient I wouldn't trust that L15 to be a reliable DD if it's also being beaten up on track days. The 10th gen also has problems with it's clutch struggling to hold up on near stock power levels, all things to consider. But the 10th gen benefits from being built on a platform thats a decade newer than it's predecessor, its lighter, stronger and designed to privilege handling.

 

BTW... I just came across this photo I took with my phone, sitting and waiting in line for my final 20 minute session at the track last time.

Notice the cars in front of me that I was racing with. I'd say that speaks volumes for what a supercharged and moderate suspension/wheel upgrade can do for a 9th gen for track/competition use. Stock brakes were the weakest component I ran into.

 

I had three 9th gen Si's and none were as fun at my 2007 8th gen. In stock form, the 8th gen felt lighter, handled better, and sounded better. I agree with the above post that says the 8th gen is the last true Si.