Hey guys,

Let me know if I am over analysing this whole thing here and if it is the "norm"

Quick run-down, I'll try to be as informative as I can.

I have owned my car for around 2 months now and my car is currently stock apart from an upgraded pump and heat exchanger which I fitted the other week, -10 mod and a couple of other star tweaks

I have recently replaced both drive belts 2 weeks ago and replaced the 2 batteries

When logging via the Android App Torque I have some questions regarding my boost

*FYI - I am at sea level - 30 meters above at most and it is currently around 25C-35C during the day here at the moment (77f-95f), starting/cruising IAT's today (ambient 25C) have been 30C - (86f) and after a quick boost with the boost symptoms below they rise to around 40C - (104f) - these are only going from 40MPH to 80MPH so only short pulls

My boost will initially spike to about 9.6psi and then continue to drop through the revs and then when it gets to about 5000rpm it will dive quickly to around 8psi

I thought the stock boost would have at least hit around 10-11psi especially being at sea level - then still loose a little boost due to slip, I was not expecting it to be at such a low initial psi, especially with new belts, I know the temperature can play with this level as can flow but am hoping for some clear input from everyone if this is normal

My guess is belt slip, I know they all slip to some degree by default but to the extent where I never even hit the stock boost level? Ambient Temperature maybe?

I don't not know (apart from a belt wrap kit) what else could be replaced to help at least bring it back to the default stock figures (tensioner maybe?)

Does anyone have any suggestions what could possibly be causing the additional slip/ loss of boost that I could look at or replace before I purchase a belt wrap kit (I just don't want the belt wrap kit to be a band aid fix for an actual underlying issue)

My (stock) clutched pulley has the chirp which can be loud, also what I have noticed is that if I ever set it to manual with esp off give it WOT in 1st to 4500rpm+ and then go to shift to 2nd and take my foot off the gas as it is shifting gear there will be an all mighty belt squeal whilst shifting, this has been the same before and after the belts being replaced - I no longer do this aggressive manual styled shift due to this (basically I would do a mild 1st gear take off/launch - WOT - wheelspin change to 2nd and coast quarter throttle)

I have checked XEntry and it returns no current Faults and everything there seems fine

Apart from this lower boost reading, which I would have never realized if I wasn't logging, the car drives immaculately, although even my son agrees with me that it needs more power, I am looking into replacing the coils, leads and plugs soon with a diff flush, SC oil change, trans flush and filter for piece of mind before I go out and get a fixed pulley - and also the wrap kit which will definitely be needed with the FSP

Cheers

 

Those numbers are common for a stock E55

 

Peak boost will be in 3rd gear

 

When I had my belt wrap kit off I could get the belt to squeal when going from WOT to coast doing the same thing. Which belt are you running? My OEM belt squealed quite a bit then replaced with a Gates HD belt and it reduced slippage quite a bit.

 

The front cosmetic cover does a good job of indicating belt slip, as you'll see a trail of belt dust on the bottom of it. The spring in the SC belt tensioner on these cars does get weak.

 

9.6lbs stock sounds right. Boost will vary depending on altitude among other factors.

I was peaking ~10.3 when I was stock and it would taper off at the revs would rise. I'm peaking in the 13lbs range now with just an upper pulley.

Also, I'd highly recommend the Belt Wrap Kit. This will drastically decrease the slippage and make boost more consistent. I think the BWK is a must on these cars (all blown car, honestly).

 

Hello Everyone.

This is what helped me. When i bought a car i would always loose to the other e55 on 3rd gear. It would pool strong first 2 gears but on a 3rd i get bitten probaby by 1 full car length on 1/4 mile(402 meters) (in my coutry we dont have drag strip, just street races). I also had a loud chirp when compressor was engaging and when transmission chagses gears on WOT. So i chacked gap at SC pulley it was within specs but i made it to minimal (0.3mm). I belive specs are 0.3-0.45mm. Also i bought supercharger belt 5mm less then OEM. If i remember correctly stock supercharger belt 1295mm i went and bought 1289 dayco belt. After all this work done i almost got rid of chirp and car started to pool better on 3rd gear. Unfortunately i don't have any before and after numbers. But i do have real street experience - i called up a car i was loosing to and we had couple runs. Now he was behind, by my rear fender on 1/4 mile race. All the races were done in summer within a week difference between races and work that was done to my car. Ambient temperature was around 25C (77F). At that moment the was all stock with around 110000km (68000miles) on moter.
P.S. I would apologize for my English. English is my second language. But i just wanted to share my experience.

Thank You

 

Yeah just the stock belt at the moment - non HD

I will be definately getting a belt wrap kit but just wanted to know if things were in the norm, for example it may not have been and someone could have stated that the tensioner goes bad and to replace that first then I would have done that

 

My front cover is off, belt slippage is a given no doubt about that

Is there a way to tell if the tensioner is worn by a specific method or just by using guess/feel and a spanner

 

Welcome to the forum nafania. I never even heard of Kyrgyzstan.

 

Thank You.
I have been reading this forum for some time but never posted anything. That was my first post. Once again Thank You!