Single Turbo RX-7's Questions about all aspects of single turbo setups.

3 different motors, same blow by issue (lots of gas in oil)

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Old 12-16-09, 12:15 PM
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3 different motors, same blow by issue (lots of gas in oil)

Ok guys I've had three different motors all built by different people (reputable people) and I've had the same blowby issue. I just changed my oil last week and this week I'm about a quart or a quart and a half over the fill line today (so lots of gas in the oil). I am running a bit rich during cruise at about 10.5 or so but am working on the cruise map as we speak. I'll probably be in the 12-13 range when finished (half bridge port). If this clears up the problem then great but somehow I don't think it's this because I've got a pretty good ignition system that should be able to burn most if not all of this (4 crane coils and 2 hi-6 amps and microtech x4 box). Anyways my question is this. I've got nothing setup to handle my blowby (no catch can) I've only got the upper nipple on the oil filler tube vented to atmosphere and I barely get anything out of it at all. Should I have anything other than this setup to pull it out like a vac hose coming from before the turbo going to a catch can along with a hose coming from the oil fill tube? Just looking for some pointers on this because this blow by thing is killing me!
Old 12-16-09, 12:26 PM
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nHave you used the same injectors and fuel rails on all three engines. You may have an injector that is leaking.
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Old 12-16-09, 01:09 PM
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I find it hard to believe that 3 engines would all have the same problem built by different builders. My bet is there is something else going on in regards to the fuel system.
Old 12-16-09, 01:38 PM
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I can get the injectors cleaned and serviced again but I've had the 1600 serviced already and the 850's were brand new when installed. Now I probably had the 1600's serviced about 4 years ago and have really only run the car about 100 miles since then. Maybe the got messed up by just sitting? I doubt it though.

Yeah I highly doubt it has anything to do with the builders either. Only thing that is the same is the the last builder tuned the car rich as all get out and this tune is pretty rich as well. I'll change the oil this weekend and drive it around with the leaner afr's and see how it goes.
Old 12-16-09, 01:49 PM
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This is an FD?
Old 12-16-09, 01:57 PM
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I'd like to hear some expert opinions on this. I have the same problem, but not nearly as bad. I'm also not running nearly as rich, so i'm thinking that might be the problem.

I've also just kind of assumed that with my setup and amount of fuel + meth and 20+ psi of boost that its just part of the game and just change my oil more often to compensate.
Old 12-16-09, 02:09 PM
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I've got a line from the iron vent T-d with the oil filler thing both going to a catch can, then the catch can is vented...I hardly get any blow by stuff in there, but like you my oil is usually a quart high by the time I change the oil...that was with my bnr setup. I'm thinking I'm going to have to route the vent from the catch can to the turbo to apply a little vacuum to get some **** in the catch can.
Old 12-16-09, 02:14 PM
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This is an s5 hbp pinned motor. I'm running 850cc primaries and 1600cc secondars and I'm currently at 17psi of boost on a t70. I know the fd had some bad problems with venting to the atmosphere but I thought fc's didn't have this same issue.
Old 12-16-09, 02:15 PM
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Originally Posted by zinx
I'd like to hear some expert opinions on this. I have the same problem, but not nearly as bad. I'm also not running nearly as rich, so i'm thinking that might be the problem.

I've also just kind of assumed that with my setup and amount of fuel + meth and 20+ psi of boost that its just part of the game and just change my oil more often to compensate.
Interesting but kind of comforting hearing that someone else is having this same issue. Who knows maybe it's just something we have to deal with. Hopefully we can get it straigtened out as an oil change isn't getting any cheaper.

Originally Posted by SmogSUX
I've got a line from the iron vent T-d with the oil filler thing both going to a catch can, then the catch can is vented...I hardly get any blow by stuff in there, but like you my oil is usually a quart high by the time I change the oil...that was with my bnr setup. I'm thinking I'm going to have to route the vent from the catch can to the turbo to apply a little vacuum to get some **** in the catch can.


You know, I looked the other day and I don't believe I have a nipple on my middle iron... Not sure if it was capped or if it just never had one. Could this be causing any issues? I've always heard people cap that one and just vent the one at the top
Old 12-16-09, 02:21 PM
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Then is not sealing right
Old 12-16-09, 02:22 PM
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All three motors? Only thing I can think of then is maybe the side housings need to be lapped?
Old 12-16-09, 02:24 PM
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Might be or a stUck side seal and or the gap between the side seal and the pacman is too much

Last edited by flaco; 12-16-09 at 02:25 PM. Reason: MISP
Old 12-16-09, 02:26 PM
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On my catch can setup, the center iron nipple and oil cap nipple (which you need to add to the cap) are plumbed to the vented can and I don't really get anything in there unless you're hammering the car around the track. Street driving and dragging don't fill mine up at all.

I do get *some* gas in the oil, but not that bad. If I were to guess straight away, I reckon your 10AFR's are doing it. Thats more then a little rich in cruising, thats a little rich for full throttle! Regardless of how powerful you're ignition is, you will be getting left over gas with that rich of a mixture. Its just that the engine may run very smooth at that mixture because the ignition is powerful enough not to flood out.

Also, I've never seen an FC iron without the center nipple. Perhaps someone has cut it off and welded the hole.
Old 12-16-09, 02:32 PM
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Originally Posted by flaco
Might be or a stUck side seal and or the gap between the side seal and the pacman is too much
Well being that the builders are reliable I would hessitate to even think that both Kilo and BDC could miss something like standard clearancing of side seals but I hear yeah the side seals are the biggest cause of blowby. My first build the only part I goofed on was when I raised the rear iron up to turn it just a bit to align it properly. The side seal came out and moved about .1000th of an inch and created a new side seal groove when I tightened the rear side housing Well needless to say I had huge blow by problems. After that I gave it to the pros and I've still always had this damn blow by issue. Maybe it's the side housings...
Old 12-16-09, 02:39 PM
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Originally Posted by classicauto
On my catch can setup, the center iron nipple and oil cap nipple (which you need to add to the cap) are plumbed to the vented can and I don't really get anything in there unless you're hammering the car around the track. Street driving and dragging don't fill mine up at all.

I do get *some* gas in the oil, but not that bad. If I were to guess straight away, I reckon your 10AFR's are doing it. Thats more then a little rich in cruising, thats a little rich for full throttle! Regardless of how powerful you're ignition is, you will be getting left over gas with that rich of a mixture. Its just that the engine may run very smooth at that mixture because the ignition is powerful enough not to flood out.

Also, I've never seen an FC iron without the center nipple. Perhaps someone has cut it off and welded the hole.
Man I'm hoping it is the rich afr's because you are right 10's even on boost is pretty damn rich. We'll see soon enough I suppose. You know I had Brian cut the nipples off of the upper intake manifold and tap them for some stainless steel vac lines, maybe he did the same thing to the middle iron. I'll have to ask him.
Old 12-16-09, 02:47 PM
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NO ONE IS BLAMING ON THE BUILDER ,you just said you barely use the car that can be an issue and **** happens doesnt matter who built it
Old 12-16-09, 02:58 PM
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I know you weren't blaming anyone I was just stating the obvious, but for the same thing to happen to three different motors means either A) the parts that are being used for the motor need going over (like the side housings) B) The mixtures are way to rich causing the gas to push past the side seals c) the car needs some sort of other way to take the blowby out besides just venting to the atmosphere or d) the builders all goofed on calculating side seal clearancing which I would find this one to be the most unlikely of the possibilities however needed to be put in just to lay out every single thing that can cause blowby.

Last edited by hondahater; 12-16-09 at 03:07 PM.
Old 12-16-09, 03:25 PM
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but how bad is the blowby???
Old 12-16-09, 03:27 PM
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******' bad man I mean a quart to a quart and a half after only about 50-75 miles or so and about 10 pulls at the very max (still tuning).
Old 12-16-09, 03:42 PM
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I'd lay my money on the mixtures.

I know back in my haletch/several blown engines phase that when I'd be tuning a fresh engine from start, with rich cruising areas, it would take very little time for the oil to get REAL gassy.

Get it up in the low 14's on the HBP in cruise and see how the problem is.
Old 12-16-09, 03:50 PM
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alright will do. I wasn't sure if I was going to tune that lean just because when I did I noticed extremely high egt's. Like 1600*f. Kind of scared me a bit.
Old 12-16-09, 03:58 PM
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Originally Posted by hondahater
alright will do. I wasn't sure if I was going to tune that lean just because when I did I noticed extremely high egt's. Like 1600*f. Kind of scared me a bit.
If they're that high the base timing may be off. Plus I've got no idea what all was modified on the MT ECU's lead ignition maps. If spark is firing way late it'll produce that high of an EGT plus much more likelihood of the gassy oil symptom you're seeing.

B
Old 12-16-09, 04:04 PM
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I'll check base timing again but I ended up ditching the funky 13bre pullies in favor of a dual vbelt setup with a racingbeat main pulley just so that there would be no issues with timing. I locked the microtech timing and set the timing on the front pulley to zero degrees. Ps. still waiting on your call
Old 12-16-09, 04:22 PM
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Originally Posted by hondahater
I'll check base timing again but I ended up ditching the funky 13bre pullies in favor of a dual vbelt setup with a racingbeat main pulley just so that there would be no issues with timing. I locked the microtech timing and set the timing on the front pulley to zero degrees. Ps. still waiting on your call
Yep I'll give you a ring soon.

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Old 12-16-09, 04:29 PM
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righto chap, I'll be waiting... sorry had a super burrito today and it's making me a bit loopy.


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