RICESP Water Injected RX7

[RICE RACING]

Originally Posted by Dust

With the control valve, how low have you gotten water flow?

Current system range is 100cc/min to over 1100cc/min

[Dust]

With different parts could 100ccm be maintained with 150 psi water input?

[RICE RACING]

Running 2.4 bar gauge boost pressure or just a shade under 35psi, the car kind of accelerates pretty quickly Traction is an issue (surprised ha ha) even with the race tires on the back.

100% pump obtained BP Optimax fuel only, no octane boosters needed

Rice Racing RRWEP140 Water Injection wound out to its maximum! *a huge amount of WM50 going through the engine* charge temperature is still under control (better than what I had a couple of years ago running ~17psi boost pressure!) water temp great, engine just loves it. I can't run any more boost pressure on this turbo without greatly over speeding it (it is well off its compressor map now, flow and speed off the charts!) but keeps on making power and the car is just faster in every test I put it through.

This is it for this set up (when my work allows *free time pending* I'll run a couple more tests, post up some performance graphs, maybe even a video). I'll focus my energy on my other long term project that should debut some time soon, where I will really push my development for the ultimate in street rotary powered super car beaters

[Grant M]

What is the in car power meter reading now then Peter? Did you get to that dyno in January?

Will you be posting up you new project on here? I'm hoping that it will be a 20B project.

[RICE RACING]

Originally Posted by Grant M

What is the in car power meter reading now then Peter? Did you get to that dyno in January?

Will you be posting up you new project on here? I'm hoping that it will be a 20B project.

I do around 400rwkw on my proper measure with the VBOX, this would be around 500rwkw on a guess mashine lol

I went to the show and the dyno did not show! no excuse offered as to why... must be scared of a little rotary turbo beating all their nugget V8 dinosaurs haha.

Next project has been work in progress for a while, long term thing, I'll update when it gets further along, probably start another thread on it.

[madbouncy]

I've always been impressed by what you've done on the other forums and it's funny it took me this long to find your actual build thread. Just read through and it's an amazing build, especially the wing that reminds me of Joe Dirt

Now you talk about how you have been messing with the mixture of water vs fuel on this car for years but you've never mentioned the timing. Have you been just doing little tweaks with timing or has the setup required retiming entirely even at the same boost? Such as when you first made your 17 psi base runs vs when you made them now and were much faster.

[RICE RACING]

Originally Posted by madbouncy

I've always been impressed by what you've done on the other forums and it's funny it took me this long to find your actual build thread. Just read through and it's an amazing build, especially the wing that reminds me of Joe Dirt

Now you talk about how you have been messing with the mixture of water vs fuel on this car for years but you've never mentioned the timing. Have you been just doing little tweaks with timing or has the setup required retiming entirely even at the same boost? Such as when you first made your 17 psi base runs vs when you made them now and were much faster.

Ignition timing for rotaries is always around a certain base level (when you run this combination of parts). The only time it ever varies is when you have a very poor intake manifold (and resulting poor chamber filling) and you need to use allot more ignition advance to make power.

As intake manifold boost pressure has gone up normally ignition timing would go down, in my case it did a little but not as much as you would expect, I tune my car for MBT but not as people would know (mean best torque) as that equals death on a rotary engine, but rather *minimum best timing*. When you run very large qty's of WM50 or water alone you need to find out what this level is otherwise you will miss out on a massive amount of power and speed from the set up.

In my own car differences of 1 degree in Leading ignition advance can change the power output by over 12% so I work off the basic principle that when the boost goes up I should have the theoretical power increase that this allows *srt(new boost/old boost) x old power* and if its not there and the mixture is withing a range of 10.2 to 10.8:1 (on a proper ignition system for the job) then the advance is lacking, so I will advance it until I reach this MINIMUM timing level to give me the power I should be getting off the new higher boost level (the timing is established at much lower boost levels that do not stress the engine as much). All in all the ignition timing I run @ 30+psi boost is not much different to what I run @ 14psi boost a few years back. This though is more related to having charge temperature well under control (sub 45 deg C) and having an appropriate AFR (10.2:1) and the right level of WM50 going through the engine for that boost/power/performance level. Spark plug heat range is also important (I run one step cooler v's what I ran @ 17psi).

p.s. You could experiment with active knock control or tuning for conventional MBT (mean best torque) but my many years of engine dyno experience running turbo rotary engines both my self and customers when testing showed that there is little reward for the risks once you have established *minimum best timing*..... the extra gains are in the order of 1 to 1.5% before the engine will detonate and die.

While I do not give out easy > "lists" of all parameters, any avid reader of this thread or my many others can find every bit of information (be it typed or data logs) they need to fill in the gaps and replicate the set up

[madbouncy]

Your experience definitely shows through with the results you have acheived. I'd prefer not to copy you outright and I'm more interested in methods right now than anything. I have no experience with rotaries and very limited with piston engines but I am an engineer so the learning and researching for me is always the next best thing to getting my hands dirty. Your thread did motivate me to pull the engine out of my car this week but I have to graduate and get a job before I can even afford an ecu.

When you say that mean best torque lead to death for the rotary, what were you finding was happening? Do you think it was just overall heat or something more along the lines of a peak pressure getting too high?

Also, if you're loosing a lot of power by backing off one degree, are you finding that the timing has more of a hump and you're just on the rising edge or if you advanced further would it fall off just as quick?

[RICE RACING]

I'm happy that its inspiring in some way its what this web site is about #1

For the timing its more of a plateau, the general slope though once you are onto it is up but the nearer you get to the end its like cliff not in performance drop, but in uncontrolled detonation. The chamber pressure gets high, but as you can imagine it gets many orders higher once detonation onsets and thus must be avoided at all costs especially at these high performance levels.

My theory and experience mostly leads me to the beginning of this "plateau" and the performance is exceptional once you get there V's what its like with only a degree or two less (when being conservative and feeling your way to where the engine starts to work well). At these levels its about self preservation and reliability and not about ultimate power output nor fuel economy per unit horsepower.

[madbouncy]

Your explaination of how you tune on AI would explain why people in the subaru community where ethanol is available are so in love with it. It basically comes down to being too conservative to give the car a proper tune on gas but once they have their magical ethanol in there they can go all out. Especially since a lot of the guys will run AI injection that still run pump gas. However I think it's more of a way to just turn the boost up to make power and not so much worrying about timing. Then again, all the internet tuners that talk about it on the forum make it sound as though you're lucky to gain more than 2hp by optimizing the timing for the fuel and sadly I think a lot of the people that have the correct answers aren't willing to share the info.

It does show that even with a good knock feedback system like the subaru's, unless its actually on the threshold and looking for knock the system really isn't doing anything. What I'm hoping is that I can use the knock feedback type system to help get closer to what you've acheived in a shorter time frame, I would love to have your experience but I don't see myself matching you in the time it takes to build up one car. So the more sensors I can have on my side the better.

By the way, I'm sure you're following Howard Coleman's turbo thread on the other forum, but it's interesting to see how his setup is basically turning into yours but with a high pressure pump.