The Twin Screw Thread
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From: Saskatoon Sask. Can.
Bill,
I am thinking exactly the same as you along with the added air from the bypass. I just hope the increased fuel pressure will be all that’s needed. I like John’s solutions best so far!
I hope a few people who actually have a TS on their car will verify this for us.
I am thinking exactly the same as you along with the added air from the bypass. I just hope the increased fuel pressure will be all that’s needed. I like John’s solutions best so far!
I hope a few people who actually have a TS on their car will verify this for us.
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Originally Posted by heinrich
Good job. So Tony did you know the 951 boys .... they run 51lb injectors 
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Originally Posted by heinrich
Try swapping 7 with another Bill ...
I swapped everything you could swap - injectors, harness leads, plugs, plug wires, distributor caps, rotors, coils. It was always #7. And #7 has the same compression as the cylinders around it. So, based on that, I was thinking I have an air leak around #7 or something else leaning 7 out. Now John has raised the possibility of improper mixture and spray pattern at idle due to low fuel pressure for the injector's requirements. Why it affects number 7 more than others, may have something to do with the nearby bypass. Dunno, but since I cannot find any air leak, I'm interested in looking at Johns theory.
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Hi Bill, guess I was thinking perhaps slight clogging of #7 injector or such. I have to tell you, what you describe makes little sense because behind #7 is of course #8, and it should have even less of what #7 has little of. So WTF 
... guess it could be a small air leak at the injector hole? Try sealing/testing there for leaks by squirting something inocuous at the injector seat and watching to see if it drains?
... guess it could be a small air leak at the injector hole? Try sealing/testing there for leaks by squirting something inocuous at the injector seat and watching to see if it drains?
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He has already swapped injectors, etc.
Originally Posted by heinrich
Hi Bill, guess I was thinking perhaps slight clogging of #7 injector or such. I have to tell you, what you describe makes little sense because behind #7 is of course #8, and it should have even less of what #7 has little of. So WTF ... guess it could be a small air leak at the injector hole? Try sealing/testing there for leaks by squirting something inocuous at the injector seat and watching to see if it drains?
... guess it could be a small air leak at the injector hole? Try sealing/testing there for leaks by squirting something inocuous at the injector seat and watching to see if it drains?Rennlist Stories
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That is the way I am leaning. Shouldn't #7 plug look a bit leaner when pulled, also.
Originally Posted by Shane
It is a design flaw in the manifold and the way the bypass is set up. Weld a diffuser in there so all that air isn't concentrated right at #7.
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Maybe if all you did was idle around, which I know from experience is next to impossible when you have so much power available with a twitch of your toe. And once you open up the throttle well the last thing you are thinking about is the lumpy idle... 
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Originally Posted by Shane
It is a design flaw in the manifold and the way the bypass is set up. Weld a diffuser in there so all that air isn't concentrated right at #7.
Help me to understand HOW the bypass works. I understand that it is there to allow the boost that this type of SC generates even at idle to not get forced into the engine. Instead the air recirculates out through the bypass. It does this based on the vacuum signal from the manifold at idle. Strange that it is getting a vacuum signal if there is supposed to be boost that needs to vent. Anyway, once you jam the throttle, boost in the manifold allows the bypass valve to close.
So, air isn't really "concentrated" at the bypass tube. It's being allowed to ventilate out of the manifold via the tube. I can't quite grasp how this might affect 7, although it is certainly affecting airflow.
I thought it might be sucking the fuel mist from that area, so I took a pipe elbow and inserted it inside the bypass and pointed it towards the center of the manifold box, so the bypass would draw air from the center. Granted, this elbow could be an obstacle for airflow to cylinder 7 as well. It had no real effect positive or negative, and I have driven with it for at least 5K miles this way.
I would prefer the bypass to be more centered, but I cannot figure out exactly how it would be affecting cylinder 7, the cylinder it is closest too.
A diffuser might make sense if the air were entering from the bypass and blowing on cyl 7, but it is leaving but not entering there, correct? Even, so, my pipe elbow pointing to the center, away from cyl 7, should have helped.
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Originally Posted by Shane
It is a design flaw in the manifold and the way the bypass is set up. Weld a diffuser in there so all that air isn't concentrated right at #7.
Some sort of baffle that routes the intake of the bypass to a slightly differnt location.
Like this...
edit...or a copper pipe will do! I guess i wasted 15minutes whipping that up.
Exact principle Bill..... 
....and that didnt change anything?
Last edited by Tony; Dec 17, 2005 at 08:28 PM.
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Originally Posted by Bill Ball
It does this based on the vacuum signal from the manifold at idle. Strange that it is getting a vacuum signal if there is supposed to be boost that needs to vent. Anyway, once you jam the throttle, boost in the manifold allows the bypass valve to close.
Has anyone taken one of those clever laser thermometer things to measure the temp of the 7th exhaust port in relation to other exhaust ports? This would give some additional info.
Last edited by mspiegle; Dec 17, 2005 at 07:54 PM. Reason: spelling/wrong word