that's funny, i know ur gonna install an intercooler but i still don't see why some people still choose to run their car without an intercooler.:scratch: from a car running if anyone ever touch the compressor housing of a turbo they'll see how hot it is, so think about the air that it's compressing. anyway good to know about that 420f degree air. heard about that before("the big boys") but it was just hard to believe.

Well, I asked about this many times on here before and a lot of people said it would work. I also saw a RX7 tuned w/ meth injection and no intercooler and it worked. I guess mine is different in some way or another. Dunno…

My only guess is the difference between mine and yours Lupe is the reason (well, more like the guess) I had for moving the injection nozzles - longer time for all of the alcohol to flash. When I moved my two nozzles upstream and staggered, everything all the sudden worked. May wanna look at your setup more closely and see what it'd take to do something similar. That's my only guess. /shrug

B

well i always say that everyone's setup is different, now you're experiencing what works for you and that's where your car will get better. also could the break up issues that you had been caused by the intake temps? ask a pro:(.

Don't sweat it. It's better to be the guy that has an idea, gets off his rear-end, and spends some money to try that idea that fails instead of being like 95% of the rest of the crowd; some of which who just talk and talk yet do nothing.

B

And another thing, Lupe - draw the compressor's air from a colder spot and not the engine bay. Big, huge change on mine when I did that. May be difficult to fashion something on yours though given the position of the turbo relative to the engine.

B

^true

Dont be so hard on yourself. You were pushing a lot of boost for no ic. Live and learn


Low boost levels should be fine with no ic and AI, but once you start pushing 20+, you gotta have it.

I recently upped the boost to 15 psi.. Runs great with AI and no IC at night and in cooler weather. I am real light on the throttle during the day tho... it's hot here in AZ. Even at only 15 psi, I am convinced that having a physical IC would relieve some stress off my mind, and add even more reliability to my car.

Now the question I am facing is, how small of a FMIC can i get away with and still be more than enough for 15-22 lbs? (i'll be keeping AI obviously)

For those seeing extremely high intake temps even with large amounts of alcohol I wonder if a preturbo WI setup would help bring the temps down? With intake temps at 220*F even when using alcohol, it's surely even hotter right at the compressor, in which case water would flash (boil) and be much more effective at cooling the charge. Then alcohol could be injected to further reduce the temps.

Alternatively a 50/50 preturbo setup could be utilized to make the system simpler, while retaining the advantage of both water & alcohol in the system, and also giving the alcohol more time to flash.

In my personal WI setup even at high boost pressures my IAT's never seem to climb, once I do more testing with the fast reacting AIT sensor I have, I'll be able to see more what's going on as the water flows. I might even experiment with 50/50 at that point, though I love the freeness of water. (yes that's a new word)
Brent

Pre-Compressor makes all the difference in AITs
I've said it many times and proven it with MoTeC AIT logs.

In Addition, 50/50 also makes the most sense for a rotary. You get cooler EGTs, cooler AITs and detonation deterant all in one shot (well, I have 2 jets off the same pump, so 2 shots technically).

I'd be careful with that "Freeness" water. I hope you aren't using tap water in the radiator too!!

Some say you have to use distilled, I use RO water for both the radiator and AI tank. That tap water will wreck your sh!t real fast.

I have distilled in the radiator, but I just use tap water (well water) preturbo. I started out using distilled, and then filtered faucet water, and now just regular old water. I do have a filter in the line from the tank so no contaminants can clog the nozzle or anything.

I've read some people say to only run distilled in WI setups, but then after readings some other posts by people that have been running water for a long time that said it's pointless, I started thinking about it and came to the conclusion they were right. It's water, I drink it. Can't be too terrible for my engine to drink it too. I can't imagine any minerals that could possibly contaminate the inside of an engine that has gasoline and oil being burned through it. What could possibly happen.... pretty much nothing. The gasoline is probably more contaminated then water.

With you on that one, Brent.

B

Guess again!

https://www.rx7club.com/single-turbo-rx-7s-23/dyno-results-425-hp-%40-28-psi-pictures-carnage-847085/

Yeah.. that'd probably do it. :D

I still think my comment on the sky high air temp thing is correct, though. He'll know real quick if he gets it all back together w/ the same hardware and tries again only to find the same air temps at the same loads.

B

Got any updates B?

On the last piece of the motor. Need to get it machined for a more-or-less experimental type of engine pinning. After that's done, it's going together and into the car. I've got all the parts ready for it. Everything is done. I can't wait!

B

That sounds great man. Keep us in the loop.

Chris

I definitely will, Chris. I'll be linking over the build folder once I get it all together as well as probably spamming the first few datalogs.

B

In case anybody is interested, here's the pictures of the carnage:

http://bdc.cyberosity.com/main.php?g2_itemId=14339

Just thought i'd throw in a comment showing my appreciation for all the detail you've gone to through the process. It's great and whilst it's always bad to see another engine hit the graveyard I really love the amount of information you've provided for others.

Was following this on teamfc3s and thought i'd finally pop over here and see where you'd got to.

Sept 22, 2010 Update
 

I'm resurrecting this older thread with an update.

Back in July and August I rebuilt and fixed my setup. Other than some minor changes (added a pair of MSD 8509 boxes to convert crank angle sensor output to Hall input for the Haltech, spark plug wire separators, and changed trail plugs from BUR9EQ to R-6725 11.5's), the majority of the setup remains the same. I wanted to be able to more or less jump back to where I'd left off when the last engine cracked a housing and just continue onward. I wasn't done with the experiment. The setup still consists of the following:

- Half-bridgeport S4 engine w/ 8.5:1 rotors, clearanced, balanced, and machined to 3mm, factory 27lb cast iron flywheel w/ ACT 6-puck clutch and heavy duty pressure plate
- Running NGK R-6794 10's in the leadings and R-6725 11.5's in the trailings
- Haltech E6K using two MSD 8509s for trigger input, shielded CAS harness
- Factory 2nd gen ignition using two trailing ignitors an four trailing coils, elimination of waste spark on leads, simulating direct fire
- Machined and "pocket" pinned housings
- Solid upper dowel runs, bypassed front cover o-ring, modified oil pickup and pump galleys on front iron, -6AN loop line off rear iron
- Twin -6AN full parallel fuel system using 720 primaries and 1680 secondaries, Mallory competition fuel filter, dual Walbro 255lph GSS342 pumps (using only one)
- Master Power T70 turbocharger, full T4 w/ 0.96 A/R P-Trim turbine housing, HKS old-school log manifold (undivided), and twin EGT's
- No intercooler; hot-air setup with custom made 2.5" piping from turbo discharge straight to throttle body
- Alkycontrol.com alcohol injection system using two M10 (10gph@100psi) nozzles, staggered 10", and placed well up-stream, being used as charge cooler, using 100% methyl alcohol

The build thread can be found here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/bdcs-fc3s-build-thread-july-2010-a-911726/

The experiment is still the same two-fold endeavour:

1) Try and determine how much boost/power one can make with a heavy ratio of gasoline to alcohol (at least 75/25 respectively)
2) Datalog, graph, and scale intake air temperature relative to alcohol injection to determine if it can be made into an effective charge cooler over and above a standard air-to-air intercooler

I've gotten the motor broken in and have been playing with the car quite a bit the last few weeks. Today I got it up to 27psi of boost. Injector duty cycles, from the only piece of log I was able to get, were at 62% at that boost at just above 6krpm. I suspect I am getting close to the output capability of the turbo and related plumbing setup and may have to go from T4 to T6 architecture. Until I dyno it, however, I'll remain optimistic and shoot for my goal of 30psi of boost (2Bar). I'm currently running low to mid 10's at 15psi and above. My target is ultimately 10 flat:1. This is possible using the amount of alcohol I'm injecting as a replacement to gasoline. I'm assuming a ratio of 75/25 of gasoline to alcohol at 15psi and above but adding excess alcohol to add another point to point and a half (from, say, 11:1 - 11.5:1) to use as both charge cooler and combustion chamber coolant.

The ambient air temps today were between 85-90* at mostly about 90. Cruising IAT's when fully warmed up were approximately 137*F which follows the older discovery from last year that those cruising temps will always be about 45*F above ambient temps. Even though I was alone and had spotty datalogs (for some reason I cannot get the system to datalog well through this new laptop/dosbox setup), I was able to get some IAT vs boost readings:

20psi 110*F
23.9psi 113*F
24.6psi 115*F
25.5psi 118*F
26.4psi 121*F

At 27psi the air temp dialed itself in at 123* and held from what I can tell. So far, I've yet to hit 130* while under boost. It pretty much shows me that part 2 of this experiment is an unexpectedly raving success. The key is to place the alcohol nozzles as far away from the throttle as possible to yield the alcohol enough time to flash from atomized form to vapour. Having them close to the throttle did not work.

1bar of boost IAT's usually hang around at or slightly below ambient temps. Right on!

One other thing I removed was the hard spark cut rev limiter. I basically set it above 10,000rpm so I'll never hit it again. Both engines cracked a housing right at that rev limiter RPM and, even though I suspect my issue was originally RF/EMI noise bouncing on the trigger harness and lousing w/ the ECU, it's coincidental that they both broke up at that RPM. It reinforces my gut feeling I've got about rev limiters and these engines.

Attached are two images of the engine bay taken today. They show a close up of the two nozzles on the hot-air pipe along with their newly-installed check valves. These check valves, rated at 10psi, help alleviate the boiling alcohol problem I was having by keeping the system primed once it's been run once. It eliminated all of the on-system lag I was originally having.

B

https://www.rx7club.com/attachment.p...3&d=1285187015

https://www.rx7club.com/attachment.p...6&d=1285187062

Thankyou for documenting all of your efforts and learnings.

I'm a little surprised that you are running a BOV?? Do you get any spray back from the methanol into the bay :lol:

27 PSI on pump?

that's an amazing achievment! and of course without an IC...

there certainly is a tradeoff w ICs. they are very heavy, bulky, add weight to the front wheels which is evil, and no question take 1 to 5 psi out of the motor...

they do, when properly fixtured, take 130 degrees out of the charge air. while that is a glorious thing if you are able to run 27 psi and your temps are really nice and your engine is in one piece... (and of course you have the resolve to run 100% meth)...

maybe you just don't need the 130 degrees, or the intercooler.

you do have me thinking:)

CONGRATULATIONS ON YOUR MAGNIFICENT ACHIEVEMENT!

howard

Thanks, Howard.

wow congrats Brian nice to see you are sticking with your alcohol injection experiments. Now would this just be strictly if you want to run without an intercooler to keep water temps down if you have a problem with them? I mean if you can do the same thing with water and it not cost anything I'm just wondering what the main benefits would be to running an alcohol system rather than a water system? None the less I've never seen anyone else run that high a boost on alcohol so that is really freakin' cool :)