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  • #16
    I think you'd be closer to 320-330 BHP at the crank at that boost level judging from KA dynos.

    I think 300 BHP at the crank is closer to what an SR would be pushing at that boost.
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    • #17
      Originally posted by Matt93SE View Post
      I'm using an S14 with 248/248 cams, I/H/E. it's otherwise stock, including the ECU. the thing really doesn't even come alive until above 5000rpm, and pulls great to redline. shifting below 6200-6300 puts it below the power band on the other end so you're bogging it and losing speed, especially when you're shifting to 3rd and 5th because of the huge gaps in gearing. 3rd to 4th isn't bad though.
      I think we've discussed this once already, but at Watkins Glen going up the esses to the back straight, I was keeping it in 4th gear instead of shifting into 5th to make it easier to get setup for "the bus stop" and because it felt faster.

      Another driver (new to Watkins Glen and wheel to wheel racing) on the team shifted into 5th gear. His lap times were approximately 7 seconds slower than mine, but he had a higher top speed by about 2 mph at the braking zone for the bus stop. Data recorded using TrackAddict app on an iPhone 5s. Whether or not that would translate into faster lap time for me remains to be seen.
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      • #18
        Originally posted by Def View Post
        I think you'd be closer to 320-330 BHP at the crank at that boost level judging from KA dynos.

        I think 300 BHP at the crank is closer to what an SR would be pushing at that boost.
        Perhaps my pressure drop is a bit conservative as well, and I also have the ambient temperature relatively high.

        I'm curious if anyone tracks a KA-T with stock pistons at this level. Where are the KA-T people at?!
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        • #19
          Originally posted by gills View Post
          I think we've discussed this once already, but at Watkins Glen going up the esses to the back straight, I was keeping it in 4th gear instead of shifting into 5th to make it easier to get setup for "the bus stop" and because it felt faster.

          Another driver (new to Watkins Glen and wheel to wheel racing) on the team shifted into 5th gear. His lap times were approximately 7 seconds slower than mine, but he had a higher top speed by about 2 mph at the braking zone for the bus stop. Data recorded using TrackAddict app on an iPhone 5s. Whether or not that would translate into faster lap time for me remains to be seen.
          I have a hard time believing a nearly stock KA can pull 5th gear with a 4.08 diff. My car with a 4.63 diff and T25 at 7-8 psi was nearly at a standstill in 5th gear, gaining about 2 mph over the whole front straight after the shift to 5th. Granted I have a little more aero drag, but my gearing is also way more aggressive.

          The 7163 at ~13-14 psi can pull it no problem (top speed at TWS went from 122 to 134ish mph).
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          • #20
            Originally posted by gills View Post
            Perhaps my pressure drop is a bit conservative as well, and I also have the ambient temperature relatively high.

            I'm curious if anyone tracks a KA-T with stock pistons at this level. Where are the KA-T people at?!
            Are you inputing the HP at the crank? I'm betting it's using that for a flow value directly.

            As for engine VE. My SR with a T25 at 7-8 psi with an exhaust, FMIC, otherwise stock was at about 106-110% VE in the midrange, and it'd drop down to about 95% at redline (stock cams, S15 SR). The 7163 and Full-Race TS manifold has a midrange VE of about 115-120% at 13-14 psi, redline VE is around 102-105%. No other changes. It's pretty similar at higher boost as well, since I'm not taxing the compressor wheel at all.

            This is on a not very exciting stock SR, so I tend to believe the oft quoted engine VE percentages in boost (~80-90%) are from a much earlier era of crappy engine design like the 70's and 80's.
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            • #21
              Originally posted by Def View Post
              I have a hard time believing a nearly stock KA can pull 5th gear with a 4.08 diff. My car with a 4.63 diff and T25 at 7-8 psi was nearly at a standstill in 5th gear, gaining about 2 mph over the whole front straight after the shift to 5th. Granted I have a little more aero drag, but my gearing is also way more aggressive.

              The 7163 at ~13-14 psi can pull it no problem (top speed at TWS went from 122 to 134ish mph).
              Best believe it my friend. It was consistent between the two greener drivers who shifted into 5th and two (myself and other faster driver) who didn't, although the other fast guy did occasionally shift into 5th. Let's put it this way, their top speed was never lower than ours going into the braking zone and were often faster. This was with the S13 engine as well. And the speed data from TrackAddict using 1Hz smartphone GPS signal is the most accurate in a straight away.

              Originally posted by Def
              Are you inputing the HP at the crank? I'm betting it's using that for a flow value directly.

              As for engine VE. My SR with a T25 at 7-8 psi with an exhaust, FMIC, otherwise stock was at about 106-110% VE in the midrange, and it'd drop down to about 95% at redline (stock cams, S15 SR). The 7163 and Full-Race TS manifold has a midrange VE of about 115-120% at 13-14 psi, redline VE is around 102-105%. No other changes. It's pretty similar at higher boost as well, since I'm not taxing the compressor wheel at all.

              This is on a not very exciting stock SR, so I tend to believe the oft quoted engine VE percentages in boost (~80-90%) are from a much earlier era of crappy engine design like the 70's and 80's.
              Yes, this is being entered as crank HP as that is what it asks for.

              Did you derive or measure your VE? Would be nice to see some KA numbers.
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              • #22
                I honestly have no idea if it's because of the fillet or nitride coating. Ive gotten one ka24de crank that was already cut slapped it in and it broke.

                Sent my prelude spun bearing crank to get cut, slapped it in, it broke after an hour of dyno tuning and 3 passes on the 1/4 mile

                My buddy sent his honda crank to get cut at a totally different machine shop and lasted an event but broke while driving home.

                After seeing it happen 3 times, I decided it's not worth messing with it when your investing so much time to initilly assemble your motor.

                They were standard king bearings.

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                • #23
                  Originally posted by gills View Post
                  Best believe it my friend. It was consistent between the two greener drivers who shifted into 5th and two (myself and other faster driver) who didn't, although the other fast guy did occasionally shift into 5th. Let's put it this way, their top speed was never lower than ours going into the braking zone and were often faster. This was with the S13 engine as well. And the speed data from TrackAddict using 1Hz smartphone GPS signal is the most accurate in a straight away.
                  1 Hz GPS - there's your problem. The final speed change is probably over ~1 sec, and the GPS is not reliably picking up the peak and/or having extrapolation errors. My speeds are from a STACK dash reading off wheel studs, GPS verified to max speed, although 1 Hz GPS has pretty significant lag, and it sometimes disagrees with the peak (I can do a recall of all peak values on the dash). I've noticed the speed on GPS can vary by about 2-3 mph from actual peaks, higher or lower since it's measurement variability.

                  I'm not saying the car is pulling harder in 4th gear, but our top gear is so tall that in both cases the car is likely about stuck against the aero wall in both cases at that power level.


                  Yes, this is being entered as crank HP as that is what it asks for.

                  Did you derive or measure your VE? Would be nice to see some KA numbers.
                  It's not derived off a formula/guesses - that's the actual VE for that AFR based on the AEM Infinity's fueling model and all the inputs. It's measuring MAP, RPM, IAT, and fuel pressure, so I'd say it's pretty darn accurate.

                  I imagine a KA rolls off a bit harder up top given the stock crank HP vs. an SR, but peak VE under boost is probably about the same in the midrange (3.5-4.5k RPM). Figure maybe 5-8% less VE up top give or take as a rough guess?
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                  • #24
                    Originally posted by Def View Post
                    1 Hz GPS - there's your problem. The final speed change is probably over ~1 sec, and the GPS is not reliably picking up the peak and/or having extrapolation errors. My speeds are from a STACK dash reading off wheel studs, GPS verified to max speed, although 1 Hz GPS has pretty significant lag, and it sometimes disagrees with the peak (I can do a recall of all peak values on the dash). I've noticed the speed on GPS can vary by about 2-3 mph from actual peaks, higher or lower since it's measurement variability.

                    I'm not saying the car is pulling harder in 4th gear, but our top gear is so tall that in both cases the car is likely about stuck against the aero wall in both cases at that power level.
                    Right, which is why I mention the frequency. But, this is consistent between 175 laps of video/data between 4 drivers split into two groups. There's a definite trend that 5th does actually result in a slightly higher top speed.

                    I have a 10Hz external bluetooth GPS receiver to work with the App that I'll be trying at my next race that will hopefully work well.

                    Originally posted by Def
                    It's not derived off a formula/guesses - that's the actual VE for that AFR based on the AEM Infinity's fueling model and all the inputs. It's measuring MAP, RPM, IAT, and fuel pressure, so I'd say it's pretty darn accurate.

                    I imagine a KA rolls off a bit harder up top given the stock crank HP vs. an SR, but peak VE under boost is probably about the same in the midrange (3.5-4.5k RPM). Figure maybe 5-8% less VE up top give or take as a rough guess?

                    Very cool. Once you sell me an EFR setup for the 2018 season, I'll have the same AEM
                    -------------------------------------------------------------------------------

                    Anyone road racing a KA-T?........***crickets***
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                    • #25
                      @gills.....if the green drivers were faster at the end of the straight, yet slower by 7 seconds overall they ate losing that time somewhere else on the track...At Watkins full my guess would be somewhere on the back half of the track..more specifically the last 2 right turns...those are easy to fubar

                      Ch

                      sent from knee deep in snow

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                      • #26
                        Originally posted by a250gpguy View Post
                        @gills.....if the green drivers were faster at the end of the straight, yet slower by 7 seconds overall they ate losing that time somewhere else on the track...At Watkins full my guess would be somewhere on the back half of the track..more specifically the last 2 right turns...those are easy to fubar

                        Ch

                        sent from knee deep in snow
                        Oh yea, 100% they were losing time everywhere, not just the back half. They got screwed because our engine blew on practice/quali day, couldn't get any practice laps and didn't have any time there. But, that's my point, they were still just as fast and faster down the back straight leading up to the bus stop.

                        On another note, you have any KA-T experiece??
                        Core4 Motorsports
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                        • #27
                          Originally posted by a250gpguy View Post
                          @gills.....if the green drivers were faster at the end of the straight, yet slower by 7 seconds overall they ate losing that time somewhere else on the track...At Watkins full my guess would be somewhere on the back half of the track..more specifically the last 2 right turns...those are easy to fubar

                          Ch

                          sent from knee deep in snow
                          Well yes, that's part of the given. The takeaway though is that these rookie drivers were faster at end of the straight in 5th despite being slower everywhere else.
                          That said, engine tuning and torque curve make a huge difference in stuff like this. OEM cams have a fat modsection, but wheeze at the top. Cams that breathe better do better running out the revs.
                          Originally posted by SoSideways
                          I don't care what color they are as long as they are LONG AND HARD.
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                          • #28
                            Yea, maybe that's the difference. The S14 came being so mild it just couldn't pull at the top of 4th. No reason to run cams like that on track, when a set of 240/248 or 248/248 cams from an S13 are so cheap.

                            Gills, maybe a little too "tough love" here, but even if you do hear some experiences, there aren't a lot out there. Ultimately your experience will be unique with your own PITA issues to deal with. So I'd recommend just planning things out the best you can and taking a stab at it. I'd shake the car out at a weekend DE before doing an enduro though.
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                            DefSport Koni Sleeve and Spring Perch Buy!!!
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                            • #29
                              Originally posted by Def View Post
                              Yea, maybe that's the difference. The S14 came being so mild it just couldn't pull at the top of 4th. No reason to run cams like that on track, when a set of 240/248 or 248/248 cams from an S13 are so cheap.

                              Gills, maybe a little too "tough love" here, but even if you do hear some experiences, there aren't a lot out there. Ultimately your experience will be unique with your own PITA issues to deal with. So I'd recommend just planning things out the best you can and taking a stab at it. I'd shake the car out at a weekend DE before doing an enduro though.
                              Absolutely, that's a given. I'm pretty sure I'll be the first to use a KA-T for endurance racing here in the US. Just like I was the first 240sx to win overall in a 24 Hours of Lemons event after many attempts by others

                              I love tough love, though. Makes me angry and want to win more

                              And FYI, we were using an S13 engine for the Watkins Glen data. It was a dog: https://youtu.be/iEVqN-xTtWk
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                              • #30
                                Originally posted by gills View Post
                                And FYI, we were using an S13 engine for the Watkins Glen data. It was a dog: https://youtu.be/iEVqN-xTtWk
                                A tiny tidbit of input on that.. There are a couple local S13 guys who run WRL/Chump/Lemons.. they've used stock, junkyard, and "mildly rebuilt" engines, and my stock S14 pulled them all on the straights. that could also be due to driving prowess and car itself (I have mild aero and expect corner exit speeds would be higher)... but I've come off the end of a turn right behind a couple of them and simply driven by them on the straights.

                                The first time I encountered them at a WRL race in my car, I was expecting to be nice to a fellow 240 racer and simply bump-draft them down the straight.... I caught them so fast I wound up hitting them hard enough to bend my bumper support and knocked out my turn signals. whoopsies. not gonna try to bump draft those guys!
                                Originally posted by SoSideways
                                I don't care what color they are as long as they are LONG AND HARD.
                                '04 G35 Sedan 6MT- The DD
                                '96 240SX- The Track Toy

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