Building for the road course...again

There are some chinese manifolds that suck for sure. That much i know lol. I also forgot to mention the resonance RPMs the skunk2 makes vs the stock stuff. the skunk2 manifold when mathed out does show the gains as i metioned from 7800 onward. Nothing factory will touch this. Even ported. Youre still dealing with the same plenum volume and runner length. These manifolds can only be ported so much, and that generally only impacts flow and not where the manifold makes power(resonances).

RPM and piston speed. Reliability. Definitely not a factor of peak power at all. that doesnt matter here. just the rpm, piston speed, overall duty cycle of the setup.

This is the surface level view of 4P. Dive into the k20a forums and youll find too many examples of their engines being junk, their advice being either drag specific or just wrong. how can a 15,000$ engine spec'd to make 330hp crank, only make 270crank when the customer receives it? its not just one example either. Then factor in after 20 hours of usage the cylinder walls are so bad the engine is smoking? again. Drag vs Road course. That engine would probably give 2-3 seasons on the drag strip. Poor guy didnt even get 1 season on the road course. There is more to this but no point getting into it its whatever. I initially was a huge 4P fan until i learned the ugly truths. Its out there just gets buried.

regardless of piston technology changing, if you are using a stock k24a with its cast pistons, which wouldve received 0 upgrades as its been sitting in a scrap yard for probably 10 years....you will not have extended success revving one of those past 7800rpm. this is well documented on k20a forums. Same goes for a k20z exceeding 8600rpm. For endurance events, back when this generation was being raced by honda, there was heavy testing. at 8300rpm, a k20z3 will last 80+ hours in an endurance environment.

At 8600 rpm, 40 hours. At 9000rpm, maybe 1 hour. The failure was a piston just exploding. The second it expands enough to even partially seize, thats it. Youre going to rip the pin right out of the piston. Or destroy a rod bolt. either way its total failure. This is with an 86mm stroke. A 99mm stroke? Well theres a reason honda didint race those. Ever. Even funny that to make a k24 good it requires k20 parts lol. It serves its purpose i wont argue that. K24 is awesome for sure. Its just not what im interested in at this time.

more stroke, only slightly longer rod, more side load. Then crank up the RPM and the side load increases. On a built motor with nice clearances maybe its not so bad but stock bottom end, add in some piston expansion and you can see where im going with this. youll destroy the walls. Rods bearings as well as you noted.

lol. yes and no. ill argue this. My honda makes WAY less power then my speed ever did. WAY less power then that GT4 Porsche i was inside of lap after lap. Power matters almost nothing if you cant drive. so no. more power is not more fast.

USING more of the car is more fast. if you can use more of the power, sure. If youre limited on tire size or compound then it doesnt matter. people often think theyve maxed out their cars and need more power or tire or suspension. Spending money is way easier then learning. It just is. 99% of the time its that they simply need to learn something new. Learn how to better use the tool you have instead of buying more tools and having no idea how to use them. This is huge in north america as you know. there are civics with sub 900hp holding records against cars with WAY over 1000hp. they have tried to grab those records and nothing. guess power isnt the answer? maybe im wrong but from what ive learned myself, i dont think so. Spend enough time at the track which im sure you have, and this becomes clear as day.

Torque over rpm is where the k20 shines lol. kinda the entire point of this build. Even if its 170wtorque, at 9300rpm...thats a little spicier then 190tq at 8000rpm, which will be a hell of a build to hold that torque at that rpm in a k24. its not a massive difference no, but again, as you rev out that k20 its just moving into its power band, each shift landing in the meat, revving towards more meat. a k24 is moving away from its power band.

Yea ive noticed this. Im lucky my guy over on the k20a forums has the cam stuff down to a science. My current "cam of choice" is extremely spicy. Toda has however answered all of my questions so far and are extremely excited for results. This aint no grocery shopping camshaft. I may be the first in Canada with it. One of the only in north america. Japanese just do things differently you know? they get it.

haha yes. that is for sure! to think the initial plan was to build a boosted k20. Due to budget those plans changed. This build is by no means inexpensive, but it does work out to be a good chunk less then the turbo build i had planned out!

 

I don't follow NA FF all too much but from what I've seen the K24 stuff seems to be pretty popular nowadays over in JP. Maybe you aren't referencing time attack though.

Rise Up EK9 - 4P K27 (current Tsukuba NA FF record holder)
Orange Ball DC5 - K24
Aslan Spirit EG6 - K24
Yellow Factory EG6 - K20

The one thing I can say for certain is they do love their ITBs

In the past 5 years I really haven't seen anyone winning races with a K20 unless it's a PTW class and the K20 is able to get them to their power level. I get that reliability is your main concern but I know a handful of guys who have 3+ seasons on stock or mildly modified K24s revving 8K+. Just last night a friend shared a video of his stock longblock K24 swapped BRZ putting down 254whp on a Mustang dyno. Most of the K24 ClubTR guys are making 230-240whp on stock longblocks with good intakes and headers. If they were allowed to change cams they'd easily be in the high 200s without changing anything else.

If revs is what you care most about then K20 is absolutely the route to go, I just don't necessarily think it's the faster route

 

But revs sound cooler

 

i am OK with my k20. Again, you have similar mindset to most racers around here. More power is more fast.

No. Better driver is more fast. Thats always, regardless of power. I can promise you that one. Drag racing is different then time attack. It doesnt work the same way if you cant drive.

to think a stock compression k24 will make high 200's with a cam is obscene. What is dynamic compression? Guess that doesnt matter at alllllllllllll. Im going to say it even though i shouldnt need to, but dyno numbers are more or les meaningless so lets not even bother with that. i can tell you right now no one is making high 200's with 10.5:1 compression, oh, and thats only on the GOOD k24. The lesser ones are 10:1.

I know you well enough to know you understand how dyno's work. Dont let the numbers people flaunt be the only thing you care about. That is flawed thinking and i know you arent about that. This being said it is all too easy to put all faith in internet numbers. thats why people hang on so dearly to that dyno graph they saw once on some dyno god knows where with less then 0 info about anything other then "CaR wEnT oN dYnO mAkE tHe BiG pOwEr" hmmm yes ok we all have youtube here thank you.

Im not arguing that a k24 can be "faster" but as a blanket statement thats incorrect. If you have the same budget, a k24 CAN make more power then a k20. I wont argue that. As for max RPM however, the k20 has it all day long and overall the peak numbers wont be far off. Torque maybe, but HP, no. This is NA after all. There is only so much to be had without going stupid deep end.

End of the day i would like the k20 NA high revving experience. To me the drive is more then just building a car for 10 years only to do 5 laps with it. Literally nobody cares. No one. If i can do competitive laps, whilst listening to my hard work scream above 9000rpm, the fun factor alone is worth while.

This being said, adding another 50whp while staying in my same class? Yea ill be ok. Not here to win the dyno competition in the parking lot, i know some are however.

Power isnt everything. Thats 100% the case. It just isnt. If you suck a driving sure. If you dont want to put the time and effort to learn how to drive, also sure. Im still gathering seat time. Big power isnt the goal here. If it was i would be boosting the car then going to the dyno so i can show off. Not interested in that

 

When you step into the world of competition being a better driver only takes you so far, for any given class for Global Time Attack and Gridlife, there are no bad drivers on podiums. Car setup (and more than just making power) is crucial if you even want to have a chance at getting on podium. The driver we sponsor in Street class has been on podium every event he's raced for the past 2 seasons, that isn't by luck or chance.

As for stock K24 power, this isn't like a 1-2 car thing, there are at least a dozen guys in the Midwest here making 220-240hp on stock engines. Of course dyno numbers can be manipulated but when you're seeing similar numbers across multiple dynos it's not number manipulation. These aren't guys dynoing their daily drivers, nearly all of them are dedicated track cars and when the rules massively limit on what you can do to the engine every horsepower makes a difference on a good driver's ability to be competitive.

Power isn't the main advantage of the K24 either, it's torque. We've seen it time and time again with S2000 guys. The guys who stick with their F20/F22 get slaughtered on corner exit by the K24 swapped S2ks. Every. Time. The difference in mid range torque is significant, and when you add in E85 it gets even larger because ethanol works better when displacement is increased.

I'm not trying to dissuade you from building a K20, I think the super high revving setups are awesome and I'm legitimately excited to see your car come together. I'm saying all of this to give some background as to why the K24 is the more popular swap and in pretty much any case, other than very high revs (9k+), it is a have your cake and get to eat most of it too situation.

 

I understand where youre coming from for sure. I get it. I also cant compete in grid life just do to budget straight up. The series we have here dont play by grid life rules. Well not most of them...we have one gridlife type even which follow clubTR rules but my car would get slaughtered there as well, even with a k24 without other extensive mods that just aint happening right now. Future? yes. Short term, unfortunately not. Id love to though.

Lack of pump E85 here also sucks. Without some better fuel, the ceiling is similar here between both. Torque aside.

As for big power k24, stock k24a will do about 270whp max effort with bolt ons and a cam. You are revving that engine well past its reliability zone to get to those numbers though. You are into rod bearing service and potential cylinder wall damage, assuming OEM pistons of course. Forged you can get more, but rod bearings will still be maintenance items.

We'll see how it goes for the sake of science. End of the day its different and its the route i decided to go down. I dont think itll suck in the slightest but is it optimal? also maybe not. end of the day the car as it is has more time in it so adding a crapload of power isnt going to do much. I may go faster, but thats because the car got faster, you know?

I guess my focus is seat time machine. My current engine is high mileage, has 35 track days in the bag, so probably over 70 hours as is. It needs replacing or refreshing to stay any little bit competitive. the plan was always to build a k20, just went from turbo to NA.

Will continue to update as i go along here. end of the season the build should actually begin. For now...we track down some ferrea goodness

 

Well total and complete failure this weekend. Absolute embarrassment. Go hang my head in shame somewhere after this BS.
first session out. 9:15am. Cold. Maybe 15c. Track is frozen. Just feeling it out, taking it easy. Car feels good. Everything feels gooood.

I was 3 seconds away from my pax time already. Off to a flying start.
second session, 10:15 am. 2 laps in finding more time, check engine light comes on. Limp mode. We’re done.

Throttle body codes. Same as before. Car was done for the day. Absolutely unreal.


I need to find a solution for this BS.

My throttle body setup is as follow:
J37 throttle body(OEM from 2010-2012 Acura ZDX), 80mm inlet 70mm outlet
Stock civic si Z3 throttle body motor swapped in

This is done as i was reading/finding reporting that the stock J37 motor can pull too much current causing limp mode/throttle closure at WOT. The solution apparently was to swap for the civic SI throttle body motor.

The first one died earlier this season. It had 265k km on it. This second one i picked up from the scrap yard for 60$ then swapped the motor into my J37. This one lasted at most 2 months? Then exact same failure.

Do we blame the fact that its old junk yard parts or is there more to unpack here?

There are 2 options for aftermarket 70mm throttle bodies for my car but they too seem to be unreliable and real expensive.

do i just keep spares or what

 

i would say just keep spares but then if it were me i would end up installing one that never failed and end up hauling a box of spares back and forth for years.

 

Haha. Been there before. I guess I’ll pick up 2 from scrap buddy tonight. It’s a small part to carry around. Not a big deal

 

What about installing an inline capacitor for the 12V feed to the throttle body? That way it's voltage supply stays steady and it doesn't drop too much?

 

I never considered this. Would that work even? Just stabilize the supply to the TB. This is an idea for sure

 

Hmmm. I found this. It says FD2 but that’s just the Japanese type R version of my car.

removed for NDA compliance

 

The capacitor would store extra voltage so there wouldn't be a sudden drop. It could help. They aren't very expensive

 

I was also thinking about if you could convert to a mechanical throttle

 

Oorr you could make it MORE complicated and swap to an early K series throttle that's an electrical motor controlled cable throttle

 

I got no idea here guys. Scrap yard for another TB. Swap the motor into my big TB. Keep a spare? I don’t know lol. Maybe I should try running the bigger motor in the bigger TB and see if my car likes that. What a dumb problem lol

 

Excessive current draw has been verified to drop voltage? I'd start with verification of the issue before throwing a cap on it.

 

The issue with using the larger throttle body motor is it demands too much current at wot and that trips up the ecu causing limp mode. It’s hit or miss. Some cars have issue some don’t.

i am using the stock Honda Civic si throttle body motor in this much larger housing. My guess is at wot, that motor is struggle to keep that blade open. Motor just burns out. I’m not 100% sure it’s a power supply issue but it could be

 

I'm not sure if the ECU is reading voltage, amperage, or both. You could datalog to see which PIDs are being monitored by the ECU.

The reason for the capacitor suggestion is that it will keep the 12V supply side at a higher reading as there is more voltage readily available. That way when the amperage is needed it has enough energy to draw from.

Another option is to maybe increase the power and ground wire size. Larger wires can carry more amperage with less resistance.

Lastly you could run brand new TXL wiring between the ECU and the throttle body. I had an Acadia come into my shop with a similar concern about random reduced power. Tried everything from a throttle body to pedal to ECU.

GM TAC had me run new wires from the ECU to the throttle body with TXL designation as sometimes signals can break down across wiring even though all wiring tests good, has low resistance, and can illuminate a headlamp bulb when powered.

That did correct the concern on the Acadia so it might be something to look into.

 

Good suggestion. I can understand how new/better/larger gauge wiring could help.


Tonight I’m gonna try putting the big TB motor back in and see how my car likes it. If it’s limp mode, then I’ll need to experiment with running wiring and whatnot to keep the smaller throttle body motor alive/happy.

Someone suggested I start off with a brand new oem Honda throttle body and steal the motor from that…too bad those are $700cad so not likely that I’ll be giving that a try lol