Perhaps you can put the data where you cant read it then :evilgrin:
Ok..disclaimer. Im just the messenger for what my car is doing with a fuel pressure of 50psi at idle set via and adjustable rate regualtor and 24lb injectors.

Anyway, heres more confusion then....

3 runs 40-60 mph...
4th gear, no WOT
SLOW roll on the first. quicker on #2 and not as long of a duration on #3..traffic..
Note #1 has no lean spike...

Im just the messenger for my car. I just present the data i have, you all can clean it and fry it , i have my own opinions.
One of which is that with the lower fuel pressure your using to get your idle with the 30lbs injectors, your sacrificing a bit of tip in here and there when in off boost/roll on conditions.. I think its made more pronounced by the fact that
1) a gt has ahigher CR
2) it has different timing
3) diferent cams.

Andy, you have an LM1 correct. Get a an AUX box as well and help us all out!
That way you will have EXACT data for the kits and configuration you are shipping and much of the grey areas we are seeing like this can be better resolved to some degree.

Seth, what is MT's take on it?


That however, is a correct answer.

:cheers:

Marc's initial reaction was to add a RRFPR to the system and then dyno tune it. I don't want to go there unless lots of other things don't work. Its costly, time consuming etc.

Mike,

That was very good... no come and help me finish tuning my car :)

Thats what i have Seth. It just gives you some leway in setting a fuel pressure at the bottom end and when you are on the gas but not on boost.. Be sure to get one where you can set the fuel pressure low enough. This is the main reason i think Andy is having you guys use the ealier regulators becasue they have a lower set pressure than the stock S4s.
Id have to dig around but IIRC the lowest FP i could get was 40lbs on my regulator.
HTH :cheers:

This is what i have and how i and have it set up . I did it this way as i knew these 3 adjustments were the ones i would be messing with all the time. 2 on the Boost regulator and 1 one the RRFPR. You will have a tough time reaching the RRFPR in the stock location i think due to the rear manifold.??? If you place it there i would weld a small wingnut (steal it from your battery ground strap! :roflmao: ) type fitting to the adjstment nut on the RRFPR, it may negate you having to squeeze a wrench in there. Im not sure how tight the space is under the rear intake for you however? but its a thought.

I have exchanged some e-mails with Marc and Seth.

But for your reading pleasure........

First order of business is to get new gas. If it was not good before and and the car was pinging on the dyno before because of this then it is going to ping much worse after the gas has sat in the tank for a month. Fuel loses octane as it sits around. Fill the tank completely with new gas to dilute the old.

A/F ratio: Unless you guys welded a bung into the exhaust before the cats for the sensor then you did not gather the proper A/F ratios. The car will appear 1 to 3 AFR points leaner than it really is if the sensor is placed in the pipe after the cats. The smog pump pumps air into the exhaust and this makes the exhaust after the cats much leaner. How much leaner? There is no set amount.
Additionally the smog pump has a vacuum actuated diverter valve (little thing on the passenger's side of engine). It will not send air to the cats when the throttle is oppened more than about half way. It just wastes the air (or sends it the the airbox it stock form) With the sensor after the cats the mixture will read much leaner at part throttle than it will at WOT because the is air being pumped in the cats at part throttle.
Monitoring the AFR behind the cats should only be exercised to record effect of changes while tuning, not to get the correct AFR.

The above issues need to be corrected before it can be said that there is need for a change.

If there is a need for a change the the order of business will be:

1 An adjustable needle valve in the line that signals the opening and closing of the bypass valve.
What this does is two fold A) It will lower boost momentarily as air is bled back through the bypass valve to the front of the SC.
B) since some air is bled back to the SC inlet, there will also momentarily be a richer misture. The MAF has told the computer
that there is more air going to the cylinders than there really is. The valve will actuate every time the throttle closes or manifold goes from vacuum to pressure.
Another benefit of this valve may be improved traction off the line, and at shifts for 5 speeds and off then line for automatics.


2 Install S4 chips. They are detuned a bit over the GT chips. Probably not a bad idea to do this on the 91 octane GTs anyway.

3 Piggy back computer that reacts faster than the stock computer and can manage timing and fuel. I know this is being worked on regardless.

One parting shot....The conditions created by having part throttle AND boost (where the ping was) is a scenario that will hardly be duplicated in the real world. The only way to have part throttle and more than 1 or so psi boost is to lug the car up hill in a high gear which shouldn't be done anyway. You may be able to duplicate the condition by driving the car from 50-150mph in 5th but again this is something you normally wouldn't/shouldn't do either.


Seth why do you deprive our eyes? Man, get a picture of your system up.
:burnout:
Andy K

I admit it-- I have done SEVERAL 50-100 runs in 5th!!! : ) he he.

Andy, Thanks for the gameplan--it appears the "NON EXISTENT" (according to Porsche) 89 GT is a different beast in so many ways. I'll keep everyone posted on progress.

No pics yet!!! I know, I've been way bad. As soon as I get back. Anyone who is over at Devek feel free to take a few snaps (it is however, pretty dirty right now!)

Andy,
My set up pings badly if given 1/2 to 3/4 throttle under 3100 rpms so I would disagree that this wouldn't be duplicated in the real world. The set up is going in my White GT soon and this will be one of the first things (the other being a longer snout) I need to address. It was frustrating to not be able to use the torque that is so plentiful to it's fullest potential.

Congrads on the dyno runs.I bet that thing has power everywhere with that roots blower!I think that a little tunning and a tighter belt will make those numbers go off the chart!Exhaust work such as ottos x pipe will also help if you dont already have one.My supercharged gt has no detonation even with aftermarket chips in it.I think my high altitude has a lot to do with it though. Good luck with your toy!

Sorry I came in late on this thread. If the car in question is running weak on part throttle, then the fuelling is clearly far enough out for the O2 loop to have control.

Is this the case ?

Jim,
The funny thing is that yours and Seth's do just the opposite. Yours didn't ping while rolling in but did when the throttle was slammed to the floor at 2500rpms. Seth's didn't ping when the throttle was slammed to the floor but did while rolling in.

John,
No.

Independant control of spark and fueling (ms, duty cycle) would obviously solve all of this - even with a piggyback.

Here is another update:

Marc at Devek has made custom spacers for me to solve the rubbing issue and the belt walking issue. This involved considerable time. Marc also installed the bleeder valve.

Andy's directions call for a setting with an 8 second delay on closure. despite several attempts, marc could not get a setting at 8, only 7 or 9. thus he chose 7.

the belt must be slipping as i dont see above 4psi on the guage, though I wonder how accurate the gauge is. the car does not feel as "urgent" when I get on it now that the bleeder valve is in place. i'll have to try and figure out if this is the valve or belt slip.

idle is still a bit weird at times. sometimes its nice and flat (for a gt) then sometimes it goes up 200 rpm. sometimes its a bit rough.

of course, this is only 1 hour of driving time.

Ever since I did a stereo upgrade i've had a system whine. Its now worse. It has to be a ground/electrical issue--right??? that damn whine is louder than the fricking S/C--how screwed up is that?? It sounds the same too!! got to trace that down.

anyway. day one is over. battery died in the parking lot--not charged enough at devek before i left. oops. got a jump from a guy at work who said "strange engine you got there"

if he only knew the 1/2 of it!

i'll be at carlsen tomorrow am at 10:30. the project is still in the early stages. guages are rough and install has not been prettied up. it will be there though for all to see.

hope to see you all there and then later at SITP on 5/21

8 sec delay? Im doing 85+ mph by 8 sec?
Can you explain what this is or what it is set to accomplish?
I assume your bleeding boost, im not sure what else it would be?
Bleeding any air off a system, while perhaps being beneficial to a specific application, is wasting the energy you used to create it. It takes a chunk of HP to drive superchargers of any type.
Quiet Herr Kuhn!!! :p


get some paint and mark the pulley and the edge of the belt at several spot...1 mark...2 marks..3 marks.. or 3 separate colors Do it that way so the odds of them lineing up when you shut down to check are greater
HTH

:cheers:

A tip I got for Mark Anderson:

I used the 1986 lower rad hose on my S4. It clears the Power steering pump by half a mile, no spacers, no eliminating the third bolt, no yanking the PS pump. It only needs to be trimmed about a half inch on the thermostat side to clear the fan blades. Oh, and no zip ties required.

Andy ought to charge people and just put this in the kit. Way easier than screwing with the PS pump.

Yep, the 86 hose is the only way to go.