Yes its me. Thanks for your previous help and comments now. I think you are either missing something here, or im missing something. From all my research, a boost curve on a car is NOT like horsepower. Whether the boost is on an 03 Cobra or a FGT, or a Lightning.... the boost line should be a smooth, linear line. If the boost line has dips and waves in it, something is wrong.... usually belt slippage. But in our case, the car showed this type of line even when totally stock. So, regardless of the total boost the car makes, how do you explain the fact that the line has these dips and waves in it when the other "normal" boost lines are smooth? thanks!
Great; I am glad it is who I thought it was.
It has been many weeks since we chatted as such I hope that you are doing well.
When I saw the thread I saw low on boost and did not associate the less than smooth curve that you had been dealing with earlier.
You are correct that even though the amount of boost can and will vary from gal to gal even if there power plant is the same the boost once it begins to build should remain fairly smooth; now I say fairly with turbos having the significant hedge here over roots style superchargers..
The roots style supercharger is archaic by design even though over the year many twist and tweaks have been done to make them more efficient
The roots style supercharger is notorious for ever increasing discharge temperature as the boost builds, air flow cavitations within the housing and then add to this in order for these units to be more user friendly for day to day driving the OEM incorporate a by-pass circuit to allow complete and rapid discharge of the pressures under deceleration and shifting when compared to a similar unit used strictly for racing on which there is no by pass circuit but rather a pop off valve aka bust plate to allow a quick exit of uncontrolled pressures with in only if needed.
I do recall looking at your dyno sheets and even chatting with the technician working with you several times and there was a wave pattern that at first glance appeared to be a by-pass valve cycling however I remember well that this item was swapped, that the OEM pulley was reinstalled and then during every test (as I recall) the results were very similar. Then Bony’s OEM supercharger was installed as yet another comparison and once again the results were the same. Now add to this I have come to understand that you have replaced all of the gaskets including the primary intake gaskets and the measured results are still the same.
So what is the cause; and once defined is the cause a problem. Now this is the million dollar question because coming back to the measured results; your gal on the dyno is very strong.
1. It could be simply the by product of the design of the supercharger and or the by-pass system as I have mentioned on several occasions that at max RPM these superchargers are operating beyond the OEM design limits
2. Could you be getting valve seepage; doubtful as the boost never spikes up beyond the max but rather drops slightly and then back up again. Furthermore your vacuum is stable and normal.
3. Could it have to do with the state of tune; doubtful as the results remained consistent whether she is in OEM trim or with the smaller pulley and the associated tune
4. Would it be a leak down issue at one or more of the cylinders; doubtful and yet you have gone this far why not do so
5. Could it be the intake tube collapsing and then expanding as it momentarily gasp for air; certainly the measured event could make sense of this happening however as I recall you have a stiffener installed on the intake tube
6. Could it be the PCV system sticking and releasing; I do not feel that enough primary air is received from this area to be create such an issue
7. Could it be a head gasket; no
Well knowing what it takes to make a gals heart come to life and sustain a heart beat I can see nothing contributing to this slight cycling of boost other than design characteristics which at the end of the day produce some rather nice results.
Now for what it is worth; I have been down roads where in my heart something simply does not feel right and I have tossed and turned until it drives me crazy only to find that at the end of the day I can not find satisfaction. I have also on occasion had to pass the gal on to another owner that once received enjoys her and then I either move on or purchase another somehow believing that the problem is behind me when in fact it remains as it was.
No I do not think that you have been on a wild goose chase because this process has remained important to you; add to this I respect the fact that through it all you have remained committed to finding the culprit and creating the desired outcome. I just hope that you find it; meaning the desired outcome even if it is simply validation that it is the norm otherwise I suspect that frustration is soon to follow.
A most sincere good luck
Shadowman
