I just looked at a lot of my datalogs from the past year, all the dyno pulls and runs at the drag strip. I started getting a few knock spikes in the 30s and more activity in the 20s after I had the problem with the water injector check valve and that's also when it lost some compression and power. Before that knock was always below 20. On the day the engine blew that was right after I switched my water injector setup and was injecting less water and that was the first time I seen such high knock numbers.

 

Tom, how many CC of water are you spraying? Im doing my single build as we speak and David from CoolingMist recommended me that for 500whp the CM7 (500-620cc) would be fine.

 

With my new setup I was using a 315 cc nozzle pre turbo and a 130 cc nozzle post ic.

"30-3000 kit came with 130 cc/min, 315 cc/min, and 550 cc/min nozzles. The flow rates listed are at 150 psi of line pressure. If you have the newest pump you can expect up to a 25% increase in flow due to the higher outlet pressure."

I would suggest running at least the 550 or cm7. I was using the 550 nozzle before, I also used the cm7 last year.

 

Thats the one i got and will be running, CM7. Just wanted to make sure that size would be enough for 500whp on pump gas. I have the new 200-250psi pump so i guess flow should be close to 620cc

 

Tom,

You had detonation.

I couldn't find which size fuel injectors that you are running but I think you need more water (really meth/water).

You need at least 25% injectorant fluid. That would be about 1275cc for a 550/2000cc fuel set-up.

Spraying since 1974.
Barry

 

Thanks for the advice. I have 2200s and 850s at around 80% max idc so that's about 4900. I will run a 50/50 water/meth mix. One reason I ran water only was to make it more simple, cost less and it won't lean out if something fails with the system and I have had things not work properly or water lines come disconnected so I didn't fully trust the system, but I got most of that figured out and fail safes.

 

For all the reasons you mentioned Tom is why i will be running pure water. And it has been proven that on pure water is good for up to about 650whp

 

I'm not clear on this Tom--were you running 100% water or a water/meth mix?

 

I was running distilled water and 93 pump gas from sunoco

 

did you ever post your timing maps in this thread?

 

They should be in one of my other recent threads with my time slips or dyno sheets.

 

Tom,
With water only you probably should limit the boost to about 20 psi.
Meth/water should take you to 30psi.

Spraying since 1974,
Barry

 

im currently using m2 pre and m10 post straight water with 150 psi pump. running a t61 at 15 psi currently, waiting to throw some egt sensors in manifold and see what temp numbers im getting. this is on 10 greddy plugs, stock fc coils and hks twin power.

 

the engine was doing really good for a while with 24 psi and water injection, until gallons of water went through the engine do to a faulty wi check valve, then for some stupid reason I started spraying less water.

and I use to run 20 psi on pump gas on the stock turbos for a few years, less power but did ok with those haha

Thanks again for the good advice

 

Tom, your engine could digest 40,000 cu. in. of water at 8000 rpm just in the bowl area.
(9:1 compression, 40 cu. in. per rotor, one face per rev.)

The chart provided shows 20 psi as the working limit. It was established with a safety margin of 7% from incipient knock.

Were the rotor dents on the trailing side?
Barry

 

You could consider switching to a series 4 rotating assembly, which has the stronger casting rotors and lower compression ratio of 8.5:1 .

Barry, the chart you posted came through as small and unreadable--there is no link to a blown up version. I did read the source paper with that chart though. The general trend lines were the same--alcohol mix allowing more chamber pressure than water, and an optimum range of injection more (more isn't always better).

 

I think the dents are all on the leading sides. The rear rotor has two bad decent size dents, on the leading side, and the front rotor has two smaller dents, leading side. One rotor face on each rotor does not have a dent. Here is a pic of the front rotor - http://czfitnessproducts.com/tom94RX...e/IMAG0199.jpg

Thanks.

 

howard is pretty spot on with the rx7 knock setup that it has. it is basicly a caution number. i look for similar numbers as well. normal driving knock gets above 50 due to noise. under throttle with no shifts it should be under 20.

on your setup i believe you need more water and or meth injection. just as a comparison i run 800cc post 50/50 and im done at 23psi. any more boost and its too high of egt / knock combo. im adding in another 500cc injector to get me up to 26-27psi on pump gas.

also what chuck said a page or so ago is dead on. the pre water injections basicly slow the blade so it has a bit more lag but adds to the efficiency of the compressor area to add more power. i am impressed with the difference over post. i just like the cooling aspects of the post setups a bit better.

 

wow 800cc huh, and i thought me doing 680cc of water is a lot lol i really gotta install these egt gauges to see what numbers i get.

 

Ya so maybe I'll try my 550 cc pre turbo and the 315cc post ic, 50/50 mix, and I need to start dataloging egt.

 

I really like this build and especially the previous twin turbo build!

When you get her running again can you please do a control test next time on the dyno. Something like..

Run 1 No water injection
Run 2 Pre turbo
Run 3 Post turbo
Run 4 compinations of Pre + Post.

I also get a little concerned that your pre vs post test might have been effected by your hurt motor.

I'm going to take your results on board and do my own drag strip/ road based spool comparison with and without pre turn water injection turned on.

 

I wouldn't do a test run with no WI with high boost though. And ya I will want to do more tests to compare the pre and post together to compare to just pre turbo, but if I start using bigger nozzles/injectors the tests might not be totally comparable if different amounts are being sprayed, I would need to get a bigger nozzle than what I have to spray only pre turbo or only post ic to compare to spraying both together.

I do think the motor was not in quite as good of condition because it was making a little less power, but only about 30 hp less so not too big of a deal, but I don't really see how that could affect the test results.

ya it would be easy to do some road tests and look at the datalogs to see how much later in the rpms full boost is acheived with pre turbo injection compared to post ic, and see how much it changes in regards to what psi the system is to start spraying.

I have also wondered how much lag time there is because if I have it set to start spraying at 6 psi, that's when the pump turns on and has to build pressure and start spraying so how much lag time is there, at what psi does it actually start spraying, my guess is there is a delay. And if my controller is set to spray the full amount at about 16 psi, is there lag time there too. This concerns me when shifting gears like drag racing because the pump will shut off in between shifts when the boost drops off completely, and then you hit the gas and boost is back almost instantly, so does it hit full boost before the pump starts spraying with full pressure again or maybe it's about the same time, datalogging the water injection pump line pressure would be nice.

 

I smile everytime I see you post after looking at your trap speeds in your sig, unreal.

 

Those S5 FC rotor housings are trashed, looks just like the other ALS seal engines I have torn down. I would not reuse those. If you can feel ridges they are out of spec, you can clearly see the ridges on your pics of the housings;



Your front is not as bad, but you can still see wear in the compression/cumbustion area.

 

Do you think most of that could have been caused by my bad water injector check valve, the water injector was post ic and the check valve was bad so the engine was sucking water through it under vacuum, the ic was filling up with water and then when I went under boost all that water was going through the engine and probably washing away the 2 stroke oil which was mixed at 1 oz per gallon. The engine was sputtering, blowing out white smoke and even stalling out/shutting off. After I figured out the check valve was bad, I went back to the dyno and it was making less power and showing higher knock, then did a compression check and the compression was lower.

And what do you think about this pic of the rear rotor? Looks like it could have hit the housing and caused many of those scratches? Thanks