Pelican Parts Forums

Pelican Parts Forums (
-   911 / 930 Turbo & Super Charging Forum (
-   -   How much HP should a 930 w exhaust make? (

JFairman 01-14-2010 03:25 PM

air pump injection nozzles
miserable things...

RarlyL8 01-14-2010 04:44 PM

I bought a set of used 930 (fuel) injectors with some other CIS stuff not long ago and the above picture is what I recieved. Not exactly what I had in mind ...

drmatera 01-14-2010 08:29 PM

well, i'm back from the dyno. We couln't get the boost over 12psi (spring is to light in the wastegate)

it made 300 hp and similar torque. I'll post the dyno sheets tomorrow

drmatera 01-14-2010 08:31 PM

oh, this was on a mustang dyno

s5uewf 03-28-2010 03:36 PM

I thought I'd bring this thread back briefly to see if folks have any more data on whether the air injection truly adds any power or just adds weight.

I have my engine on the stand and am tempted to remove the air system and save it for some future date when it may be desired (sale to someone who wants stock setup,etc.).

I have detached the fitting to the cat last year when I put on a rarlyl8 muffler. I but a bag ove the open end, zipped it closed and zipped it up to the hanger undet the fender. If the pupm was really pushing air into my cat in any significant amount, seems the bag would have blown off the fitting or at least inflated. I see no effect at all. Both solenoids are powered, the belt is in place, etc. Perhaps one of the diverter valves is stuck?

One thought I had was this - if the pump was useful in adding power by spinning the turbo - maybe if I left the injectors in place and removed/plugged the cat end to force all air into the injectors...woudl I get more power? OR would I just hose up the AFR's?

Which brings up a another question now that I have an AFR meter and adjustable WUR...should AFR's be set with air pump off or with air pump on? I would think having the ait pump running would lead to artificially lean AFR readings, meaning the engine would actually be running too rich as one woudl be compensating for the extra air in the exhaust that was never in the intake. Does this make sense?

Sorry to ramble. I guess my questions are; should I yank the air system; modify it to nly send air to the injectors; and if I leave it in should I disable it when tuning AFR's to avoid the extra air generating false AFR reading leading to an overly rich setting?

911st 03-28-2010 04:57 PM

To get usable AFR data using a wide band system you will need the air injection disabled I would think.

I have wondered what the factory procedure is for setting CO. Is the air injection pump off at idle?

Is it to be disconnected for setting CO.

Maybe the factory CO setting takes into account the effect of the air injection system being active.

I do not know.

That is another reason for removing said system I suspect.

s5uewf 03-28-2010 05:21 PM

Yes, I agree with all your thoughts on this. I figure if the system is to stay, then the best way to approach would be to disable the air system, then set AFR, then re introduce the air system and note the delta between the two states - to avoid mistaken conclusion the AFR is too lean.

Actually the graph showing the 5 HP gain/wider torque band/earlier boost is the only article making me second guess removing the air pump and system. A 20 pound weight penalty for 5HP seems a reasonable trade off - but if I am not really getting 5HP then losing the weight and plumbing makes a lot of sense. If in turn the engine is easier to tune (more straightforward, anyhow), then that is another plus.

Thisis a very interesting topic since a lot of the insight as to what Porsche might have been hoping this system to do aside from smog control seems lost to time.

So the Euro 930's have air injection? If not, then perhaps the performance enhancement is more myth - if so, then maybe there is something to this.

jay72 04-07-2010 06:13 AM

The '78 Euro 930's did have air injection. Is it possible that all the people that removed this system actually slightly reduced performance on their cars??


RarlyL8 04-07-2010 06:43 AM

While air injection may be a method to reduce lag it is not one I would use. It is far better to replace the entire exhaust sytem and turbo then tune for performance. At that point I can't see air injection doing anything but getting in the way and adding weight/complexity.
Now if the engine is stock and needs to remain that way it appears air injection would help. I'm sure the air injection system could be simplified to work specifically for lag reduction. If this is the case then the graph would indicate that it could very well be possible that some extra lag has been allowed by removing the air injection on a stock engine.

jay72 04-07-2010 01:54 PM

Makes sense.....

I thought that the air pump only works for a brief time when the car is cold.

All times are GMT -8. The time now is 10:32 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.