Re: RICESP Water Injected RX7
 

Got a phone call this morning at 7.am from a friend inviting me to go to the local 1/8th mile drag track (owner of it was running in his rail flat head supercharged methanol V8!). Could not resists so I quickly hooked up my new car trailer and loaded the Mazda on and went there.

Got a chance to run my car down there and practice some launching techniques, the thing is unreal :) 1st gear taking off simply requires a bit of clutch slip to preserve the gearbox and differential, letting the thing fully engage at 3500rpm or so it got such a great spread of power that it just spins the tires all the way through first, second gear grips up and third it was pulling near 8000rpm at the end of the 200m (100mph or so). Took max revs to 8500rpm and the hard work on improving the mixture at the higher revs did help, my passenger commented that it just keeps on making power and theorized it should be able to pull to 9k rpm hahaha (I informed him that was not recommended or needed). He was totally amazed that a road car with full legal catalytic exhaust and moderate noise level on ~17psi boost accelerated so well.

Riding in passenger seat he said in 3rd gear in last half of the track it feels as fast as his 6.7 second drag only 6cy turbo car, it was very hot today (maybe 30 deg C in the sun) on board power meter was showing 281rwkw @ 7700rpm. I took him for 3 runs back to back then did 3 or so on my own and it performed faultlessly. We have a drag event there on the 4th of April and am confident to show up and not make an arse of myself with a car that is too slow :) *I have VBOX tested his drag car, 36psi boost, methanol, 3300cc straight 6, tripple SU carb draw through turbo set up 1008kg car, making measured ~250rwkw 6.75 seconds @ 106mph in 200m test.*

Will have to implement the launch control system and also use staged boost in the hope of trying to get some better take off's........ though its not really made for that kind of activity at the end of the day it was allot of fun regardless. Will have time to instrument the car before that event and will get the VBOX data of 0-100kmh times and other performance measures also. The traction control was too invasive on initial take off and since I had not configured the launch control yet I turned it off totally on today's tests, the one thing I did learn is the fitment of the new Ohlins suspension full cured the cars tendency to wheel hop on take off wheel spin, it just sits flat and you can modulate the throttle and wheel spin with zero wheel hoping which means reduced drive line stress. :)

Re: RICESP Water Injected RX7
 

Did a 0-100kmh test today.

Bogged it badly, Launch Control was not working so on take off the Traction Control setting of 3800rpm minimum engine speed activated and for 0.5 seconds car just rolled on at a constant massive 10.90kmh :(, first to second shift was 0.620 seconds before it started accelerating again (did not use flat shifting feature) to be brutally honest it was an arse fest of an attempt!!! :( Got 5.39 seconds

Have since re adjusted the TC setting and lifted minimum engine speed activation to 5000rpm (so motor wont cut out) and increased variable boost to speed setting from 0.8bar 1st gear, 1.0bar second gear) to 1.0bar first and 1.2 bar second.

Hoping it will do ~4.0 second range or maybe crack a high 3 if I manage to perfect it.

Re: RICESP Water Injected RX7
 

Got a chance to do a run today at 1335kg test weight (27deg C day). Redid a few setting (still no flat shifting) Start procedure was release clutch at 4500rpm *no slipping* bit of wheel spin and engine dropped down to 2800rpm.......... Managed 4.40 seconds for 0-100kmh time. (will post up a graph report when I can).

There is probably 1/2 a second in refining technique and also working out boost control, as it was quite low in 1st gear and mid way through 2nd gear (1st 6psi below 4k rpm & 2nd below 12.5psi under 6k rpm). Probably best to leave boost control at the 1.2kg setting and not using variable speed boost and let the traction control modulate the power rather than the boost controller as its much much faster and more precise.

I can run 40kg less weight too reduce fuel 20kg and 20kg of spare tire, jack tools etc... Maybe high 3 sec is possible on road tires :)

Re: RICESP Water Injected RX7
 

Looks like you are have great fun with all your hard work building this machine. Would like to see 3s with perfected launch - do-able on your car.

Re: RICESP Water Injected RX7
 

Here are the files, self explanatory really :)

http://img214.imageshack.us/img214/4278/0100kmh440.jpg
Note full power not achieved in 2nd gear, in 3rd showed 273rwkw on VBOX and 276rwkw on power meter (as per averages to date)

More detail of average power delivered, start RPM and drop down in 1st gear, showing car was not abused to get the time :).......... there is some more left there as can be seen, nothing some more fine tuning of settings and technique would yield.
http://img715.imageshack.us/img715/1...00testload.jpg

Re: RICESP Water Injected RX7
 

Road testing, or grippy track testing ?

I was recently racing on a local airfield ( smooth tarmac just ) and found MT DR's offered me more grip than their ET Streets !

60fts were similar, but ET's were down 0.2-0.3 secs

Re: RICESP Water Injected RX7
 

^ Was out on highway, pulled off side of road onto dirt then back on to do the test...

I am going to my local 1/8th mile drag track on the 4th of April and will see what its like there, and can also run it out to 160kph or 100mph and get that incremental as well (in safety) :) I was at the track on Wednesday but it felt slippery as, though I was taking off totally different slipping the clutch and it was building allot more boost in first gear at higher engine rpm (left it on 1.2kg setting on boost controller). *did not have time to fit VBOX gear due to short notice*

2nd gear on the drag track on 1.2 bar felt stronger than today and more grip, the traction control was activated on the highway test on applying power and release of clutch into 2nd gear for a short bit (you can see AFR spiking lean *fuel cut of TC* looking at graphic).

I'm not really into that type of testing or performance I should say (its a bit too harsh on the car), but lots like to know the figures for comparisons to other types of road cars I suppose.

Re: RICESP Water Injected RX7
 

Turned her up to 1.40kg/cm boost setting this morning (weather starting to cool down here 18 deg C). Was boost learning *automated thing on Blitz unit* and showing 1.44kg/cm @ 7000rpm....... car has no misfires and spins wheels hard in 2nd gear when tires are cold.

Did a 3rd gear accel run down mild hill near workshop and its starting to feel really strong in acceleration I think I will leave it alone now :) ~20psi boost (243kpa absolute on ECU log) is enough in this particular road going car. When time allows will provide updated figures/graphs as always, but should be around 300rwkw level on my VBOX equipment (whatever that is at engine take your best guess!) 300rwkw on my equipment in this running weight (1305kg this mornings test) is really starting to feel good.

Re: RICESP Water Injected RX7
 

Bit more refinement and fine tuning 90-140 in 2.75 seconds
http://img243.imageshack.us/img243/8...275seconds.jpg
Power curve, I trialed the race exhaust and it was poor, the car lost power V's running the street exhaust and it was hideously loud to make it even worse, exhaust system pressure was about 50% less and turbine inlet pressure was around 12psi on 17psi inlet manifold pressure, same AFR and Timing it had up to 30rwkw less, and the volume was double :shock:
http://img534.imageshack.us/img534/4...idynosheet.jpg

Re: RICESP Water Injected RX7
 

Past another durability milestone today, have the boost set to 1.33kg/cm (showing about 18psi on VBOX in logs). Tested the engine compression after 1000km running at this boost setting and its ~120psi region. I reset the WI mixture to 4 turns (increased over the high power setting to give more safety margin) and took out 0.5 degree of timing at this boost and around 3 deg at higher boost levels (yet to try the higher level). AFR is 11.1:1 and is a bit lower to increase knock resistance for higher duty power application on track V's a one off power check.

I decided to go richer *11.10:1 target* and higher boost as its far safer (cooler, less prone to fuel quality variation that can induce pinging) than aiming less rich for optimal power at a fixed boost range setting

Power is ~280rwkw on average
90-140 times (over a spread of 6 separate tests) 2.82 seconds

My next boost increment step is 1.53kg/cm or 1.5bar (21.75psi old money!) When the weather gets cooler I will do that last step (haha for now till the next goal!) I am very happy with the power now and the way it goes "it flat out hauls" :) so am in no rush to step up to the next point............ but it would be nice to have over 300rwkw on my VBOX measure, but all at the expense of drive line durability let alone other parts so I will try to refrain from pushing more.