K24 into S2000 Race car SCCA build
11-29-2017, 10:21 AM
#751
I've driven it around a bit in my neighborhood, it's not that peppy down under 4k (but what S2000 is). But if you go full throttle in 1st over that RPM the 255 RS3's just spin.
And yes I agree anything more then 8k on track isn't gonna last. This is the long rod motor so it's go the same rod ratio as a F22. I'm feeling more confident of 8200. But I have a tune in there set at 7800 for a reason.
And yes I agree anything more then 8k on track isn't gonna last. This is the long rod motor so it's go the same rod ratio as a F22. I'm feeling more confident of 8200. But I have a tune in there set at 7800 for a reason.
11-30-2017, 05:16 AM
#752
They should, they built it. When you start doing math on a 4 inch stroke at 8,9,10k the piston velocity is getting pretty high. Like the old F1 motor kinda high. While alot of those motors would run many races without failure.... several didn't. Your playing the lotto at those kinda RPM's. While the 4P motors turning 10k on the dyno or down the drag strip aren't having any reported failures.... it's still the Lotto. I'll rev it to 9k when I take it to the drag strip in the next few weeks. I'm not brave enough to go beyond that and even at that, I'll give it one or two passes to 9k.
If they built the whole engine, my guess is they have a good handle on the parts. There is only a handful of parts that could be the problem. The dyno sheet is just beginning to taper off when it stops. Did they indicate what the replacement schedule should be on valves, valve springs, retainers, pistons, wrist pins, and rod bolts if you used 10k rpm regularly?
Doesn't STU require the stock S2k intake manifold and throttle body? If so, isn't that the final determinant of top engine speed and power levels?
Were you able to create a crankcase vacuum with your dry sump? Did 4Piston build the engine tight enough to create a vacuum with the dry sump; this is an area they are very knowledgeable. If so, were you able to determine how much power it added?
11-30-2017, 05:48 AM
#753
Thread Starter
Old F1 engines didn't have FEA for design or current metallurgy or manufacturing techniques. 4Piston builds sprint car engines and a variety of road race engines. They use a very lightweight piston. They built a 2L that made 330hp for SCCA P1 (it went into a Wolf CN chassis). They label their road race/rally engines as the " 4 Piston Racing K400 Endurance Engine" and that engine uses the more aggressive RR4 camshaft.
If they built the whole engine, my guess is they have a good handle on the parts. There is only a handful of parts that could be the problem. The dyno sheet is just beginning to taper off when it stops. Did they indicate what the replacement schedule should be on valves, valve springs, retainers, pistons, wrist pins, and rod bolts if you used 10k rpm regularly?
Doesn't STU require the stock S2k intake manifold and throttle body? If so, isn't that the final determinant of top engine speed and power levels?
Were you able to create a crankcase vacuum with your dry sump? Did 4Piston build the engine tight enough to create a vacuum with the dry sump; this is an area they are very knowledgeable. If so, were you able to determine how much power it added?
If they built the whole engine, my guess is they have a good handle on the parts. There is only a handful of parts that could be the problem. The dyno sheet is just beginning to taper off when it stops. Did they indicate what the replacement schedule should be on valves, valve springs, retainers, pistons, wrist pins, and rod bolts if you used 10k rpm regularly?
Doesn't STU require the stock S2k intake manifold and throttle body? If so, isn't that the final determinant of top engine speed and power levels?
Were you able to create a crankcase vacuum with your dry sump? Did 4Piston build the engine tight enough to create a vacuum with the dry sump; this is an area they are very knowledgeable. If so, were you able to determine how much power it added?
11-30-2017, 11:11 AM
#754
This motor is the K400 endurance bottom end with the 156 head and smaller custom cams. Since I had to have the block machined an I had ordered their cams, I was gonna buy new pistons, what was a few more dollars for their fancy long rod setup. So for the larger bore it just made more sense to send them all my parts and have them assemble it rather then pay a local machine shop to screw it up.... again, plus their machine work and assembly price was several hundred dollars cheaper then what any of the local machine shops quoted me to bore and balance alone. Now if I ever go to sell it, it's a team 4 piston Longblock.
Did they seal it for creating crankcase vacuum with the dry sump?
What engine speed did they think it would make peak power? They spec that engine with their 163 head and RR4 cams, what drove your decision for the smaller top-end with the large displacement? Are you running an intake that acts as the limiting factor? Don't STU rules require OEM intake and throttle body...specifically called out for K24 S2000s?
BTW, is it the full 2.491L (89.5x99) or did you use a smaller bore? Don't the STU rules limit engines to a 1.2mm overbore?
It sounds like you chose the best way to get a racing K24. Good for resale in part because the shop has so much experience building racing Honda engines.
The following users liked this post:
Mrsideways (12-01-2017)
12-01-2017, 05:48 AM
#756
Thread Starter
Tell me more... Very VERY intrested in this. What did yo have to change? How did yo power it? What signals does it need? what parts did you have to get?
12-01-2017, 05:59 AM
#757
The K24-S2000 STU car is allowed either the factory K24 IM and TB or the factory S2000 IM and TB, no mixing and matching, but you are allowed to modify them, I do believe. It still limits you to what is possible/legal and flow rates though.
12-03-2017, 02:41 PM
#759
The hard lines are a touch different between the years so that might be interesting but the wiring was easy:
-Obviously there are 2 wires to each corner
-pump side power and ground (constant hot 30A iirc)
-brain side power and ground (constant hot 20A iirc)
-power that comes on with IG1 (i forget the amps, its pretty low)
-switched 12v that comes off the brake pedal (i forget the amps, its pretty low)
-Obviously there are 2 wires to each corner
-pump side power and ground (constant hot 30A iirc)
-brain side power and ground (constant hot 20A iirc)
-power that comes on with IG1 (i forget the amps, its pretty low)
-switched 12v that comes off the brake pedal (i forget the amps, its pretty low)
12-03-2017, 04:30 PM
#760
