f20c with k24 crank(f24 stroker)
05-26-2016, 10:31 AM
#31
Originally Posted by wadzii' timestamp='1303094744' post='20476643
I'd keep a 99mm crank motor to 8500 rpms on the street regardless of the rod/piston combo. For drag racing turn it to whatever you want.
the only problem w/a supercharger is that rpm=boost, so if you can get the pulleys setup then you wont have any problems.
the only problem w/a supercharger is that rpm=boost, so if you can get the pulleys setup then you wont have any problems.
To match the piston speed of the 84mm crank at 9k, the 90.7mm crank would need to be capped at 8375rpm (which is why Honda reduced the redline to 8k - to give a safety margin). The 99mm crank only needs to be doing 7,673rpm to match the piston speeds of the 84mm crank at 9k.....
This is what happens to even tuner prepped cars if they are revved too high
:https://www.youtube.com/watch?v=eWUPcvF6hC4
Obviously Honda have built in some safety margin with the standard limit of the 84mm crank, but I wouldn't be wanting to be going much beyond a piston speed of 84pfs without some significantly stronger rods / rod bolts.
12-06-2016, 08:30 AM
#32
I am in the process of building an F24 stroker kit. I'm using a crank out of a 2010 CR-V and am going to buy inline pro f24 rods and 12.5-1 FRM pistons with an F22 block and F20 head with BC cams. I am going to have it tuned by Evans tuning. He tuned my car previously and I think is probably the best tuner for S2K's on the east coast and possibly the country. What kind of reliability issues have you guys had doing this? And if you daily your S how has it affected drivability? I don't daily my S but I'm curious to know because it is driven on the street and never the track. I would think drivability would improve because of the added torque but what do I know.
01-17-2017, 08:06 AM
#34
That seems awfully high to me - equivalent to revving the 2.0 litre 84mm crank to over 10,000rpm
To match the piston speed of the 84mm crank at 9k, the 90.7mm crank would need to be capped at 8375rpm (which is why Honda reduced the redline to 8k - to give a safety margin). The 99mm crank only needs to be doing 7,673rpm to match the piston speeds of the 84mm crank at 9k.....
This is what happens to even tuner prepped cars if they are revved too high :
https://www.youtube.com/watch?v=eWUPcvF6hC4
Obviously Honda have built in some safety margin with the standard limit of the 84mm crank, but I wouldn't be wanting to be going much beyond a piston speed of 84pfs without some significantly stronger rods / rod bolts.
To match the piston speed of the 84mm crank at 9k, the 90.7mm crank would need to be capped at 8375rpm (which is why Honda reduced the redline to 8k - to give a safety margin). The 99mm crank only needs to be doing 7,673rpm to match the piston speeds of the 84mm crank at 9k.....
This is what happens to even tuner prepped cars if they are revved too high
:https://www.youtube.com/watch?v=eWUPcvF6hC4
Obviously Honda have built in some safety margin with the standard limit of the 84mm crank, but I wouldn't be wanting to be going much beyond a piston speed of 84pfs without some significantly stronger rods / rod bolts.
My setup is: stock AP1 head with AP2 intake keepers and retainers, AP2 short block with CNC 2.4L stroker kit (which includes a machined 99mm K24 crank, custom rods and stronger bolts) and AP2 pistons, AP2 rings and Swaintech Goldcoat ceramic coated piston domes.
I'll likely reduce my Rev limiter to 7800 (in AEM Infinity) and configure the gaugeART CAN gauge I just ordered to warn (shift light) at an EngineSpeed of 7600.
01-17-2017, 09:49 AM
#35
Interesting. I happen to have an AP1 with the 2.4L stroker kit from Jason (wadzii). I had Evans Tuning tune it through 8200 but I've only been taking it to 8000. Now I question the wear and tear 8000 RPM is (or will be) doing to my setup.
My setup is: stock AP1 head with AP2 intake keepers and retainers, AP2 short block with CNC 2.4L stroker kit (which includes a machined 99mm K24 crank, custom rods and stronger bolts) and AP2 pistons, AP2 rings and Swaintech Goldcoat ceramic coated piston domes.
I'll likely reduce my Rev limiter to 7800 (in AEM Infinity) and configure the gaugeART CAN gauge I just ordered to warn (shift light) at an EngineSpeed of 7600.
My setup is: stock AP1 head with AP2 intake keepers and retainers, AP2 short block with CNC 2.4L stroker kit (which includes a machined 99mm K24 crank, custom rods and stronger bolts) and AP2 pistons, AP2 rings and Swaintech Goldcoat ceramic coated piston domes.
I'll likely reduce my Rev limiter to 7800 (in AEM Infinity) and configure the gaugeART CAN gauge I just ordered to warn (shift light) at an EngineSpeed of 7600.
If your redlining short of 8k (8k is still pretty low) and you don't re gear the car to get some kind of mph spread between gears, then your not going to have a set up which is very effective, your just shifting all the time. The flip side, if you do change the rear end to get some mph spread back more akin to stock, then your effectively spreading out that nice new trq bump you had from stroking the engine, effectively making it near a wash from just leaving the higher gear multiplication and higher rev band. There is always a compromise somewhere it seems, and I know there is a better sweat spot for this, but when you start talking 7600rpms, I think your compromising a lot of overall aptitude of the car. My first thought is, well what's the point then.
Last edited by s2000Junky; 01-17-2017 at 10:31 AM.
01-17-2017, 11:55 AM
#36
Kind seems like taking the fun out of owning a high revving 4 banger. Maybe an F22 is the sweet spot at 8500rpms.
If your redlining short of 8k (8k is still pretty low) and you don't re gear the car to get some kind of mph spread between gears, then your not going to have a set up which is very effective, your just shifting all the time. The flip side, if you do change the rear end to get some mph spread back more akin to stock, then your effectively spreading out that nice new trq bump you had from stroking the engine, effectively making it near a wash from just leaving the higher gear multiplication and higher rev band. There is always a compromise somewhere it seems, and I know there is a better sweat spot for this, but when you start talking 7600rpms, I think your compromising a lot of overall aptitude of the car. My first thought is, well what's the point then.
If your redlining short of 8k (8k is still pretty low) and you don't re gear the car to get some kind of mph spread between gears, then your not going to have a set up which is very effective, your just shifting all the time. The flip side, if you do change the rear end to get some mph spread back more akin to stock, then your effectively spreading out that nice new trq bump you had from stroking the engine, effectively making it near a wash from just leaving the higher gear multiplication and higher rev band. There is always a compromise somewhere it seems, and I know there is a better sweat spot for this, but when you start talking 7600rpms, I think your compromising a lot of overall aptitude of the car. My first thought is, well what's the point then.
Anyway, the prospect of reducing my redline to 7600 is not something that excites me. Jason (wadzii) said 8500 is the limit for F24C (I assume his view is built ontop of a 2.4L like the kit he sold to me -- but I do know he generally uses sleeved blocks and aftermarket pistons, whereas I'm using stock AP2). But it could easily be that I could carry on using an 8000 redline and be perfectly fine... we shall see.
Last edited by snitm; 01-17-2017 at 05:36 PM.
01-17-2017, 12:24 PM
#37
Kind seems like taking the fun out of owning a high revving 4 banger. Maybe an F22 is the sweet spot at 8500rpms.
If your redlining short of 8k (8k is still pretty low) and you don't re gear the car to get some kind of mph spread between gears, then your not going to have a set up which is very effective, your just shifting all the time. The flip side, if you do change the rear end to get some mph spread back more akin to stock, then your effectively spreading out that nice new trq bump you had from stroking the engine, effectively making it near a wash from just leaving the higher gear multiplication and higher rev band. There is always a compromise somewhere it seems, and I know there is a better sweat spot for this, but when you start talking 7600rpms, I think your compromising a lot of overall aptitude of the car. My first thought is, well what's the point then.
If your redlining short of 8k (8k is still pretty low) and you don't re gear the car to get some kind of mph spread between gears, then your not going to have a set up which is very effective, your just shifting all the time. The flip side, if you do change the rear end to get some mph spread back more akin to stock, then your effectively spreading out that nice new trq bump you had from stroking the engine, effectively making it near a wash from just leaving the higher gear multiplication and higher rev band. There is always a compromise somewhere it seems, and I know there is a better sweat spot for this, but when you start talking 7600rpms, I think your compromising a lot of overall aptitude of the car. My first thought is, well what's the point then.
About gearing: I have the stock 4.1 FD. I think it is a pretty good match. I can go 150+ mph, which is enough for me and my applications. A friend of mine drives his stroker with a 4.44 and he's very happy about it. Lots of fun.
My redline is at 8250 but most of the time 7,5k to 8 is enough, leaving it a good margin. So, I would say even a 7600 redline would be still lots of fun -- and then again: nobody stops you at selecting the right parts for higher rpm, stretching physical boundaries a bit.
Before I was like "it is an s2k, it has to rev very high" but now I would say astronomically high rpms are just a number and a psychological issue. I have more fun provided by the improved character compared to looking at 9k shifts.
01-17-2017, 12:32 PM
#38
Sure, fun is one aspect that cant be discounted, but from a applicable/performance standpoint, I'm saying the car in stock form has a pretty close gear ratio but makes it work because of the rev band (more so the ap1) if you shorten that up, your mph spread becomes compromised. Putting 4.44 with a short rev band makes even less sense for getting the power to the road. Shifting 2 times before you even hit 60mph when a motor/power curve that would otherwise pull it effectively in nearly one gear. I'm not talking about top speed limits, I'm talking about acceleration and overall usability, having the right gear for the trq curve and rev range.
01-17-2017, 01:35 PM
#39
Sure, fun is one aspect that cant be discounted, but from a applicable/performance standpoint, I'm saying the car in stock form has a pretty close gear ratio but makes it work because of the rev band (more so the ap1) if you shorten that up, your mph spread becomes compromised. Putting 4.44 with a short rev band makes even less sense for getting the power to the road. Shifting 2 times before you even hit 60mph when a motor/power curve that would otherwise pull it effectively in nearly one gear. I'm not talking about top speed limits, I'm talking about acceleration and overall usability, having the right gear for the trq curve and rev range.
7600 with 4.4 FD is nothing I personally would do (from a performance perspective, a 7600 redline is also nothing I would do...)
Measured against 2nd gear max speed, this would compare to an AP1 with 5.1 FD or an AP2 with 4.56 FD or an AP2 with 8500 redline and 4.77 FD (+- 1 mph, depending on wheel size).
01-17-2017, 04:41 PM
#40
Ah ok. Got you wrong.
7600 with 4.4 FD is nothing I personally would do (from a performance perspective, a 7600 redline is also nothing I would do...)
Measured against 2nd gear max speed, this would compare to an AP1 with 5.1 FD or an AP2 with 4.56 FD or an AP2 with 8500 redline and 4.77 FD (+- 1 mph, depending on wheel size).
7600 with 4.4 FD is nothing I personally would do (from a performance perspective, a 7600 redline is also nothing I would do...)
Measured against 2nd gear max speed, this would compare to an AP1 with 5.1 FD or an AP2 with 4.56 FD or an AP2 with 8500 redline and 4.77 FD (+- 1 mph, depending on wheel size).
In a perfect world, a motor has enough trq to not need gear multiplication, but rather one gear, go! Its why many drag cars can and will use a 2 speed powerglide as an effective option, because the motor has a high broad trq powerband to pull it and stay in the powerband of the engine with just 2 gears for the speeds it reaches and benefiting with no shift time hurting such a short run. For the same reason why sports cars/bikes/carving machines have low bottom end trq with high strung/hp engines with close ratio gear multiplication to get the most out of that kind of powerplant for in the rpms they are used. When you start shifting the dynamics of your sports car engine to favor more drag race trq/ lower in the rpms with less rpm ceiling, then that original sports car gearing no longer yields the best performance for how the car is used. Now on the street, there is a middle ground somewhere obviously, but knowing where the stock s2k is as a middle point, it makes my case in point.
A c6/ls3 has a great broad powerband but its limited to 6500-7k rpms, but it doesn't matter because that broad engine trq can pull 1 gear to over 60mph and still spin tires the whole way. If it had a gear ratio that could only get you to 40mph like the s2k with that motor, its ability to perform its acceleration task in the quickest time possible would diminish. But im starting to nerd out here a bit much so will leave it at that. Love the added power curve/numbers of these 2.4 strokers im seeing, but only if factory 8k+ rpms are reliable.
Last edited by s2000Junky; 01-17-2017 at 04:54 PM.