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Am I Expecting Too Much, Doesn't Feel Quick After Fitting Supercharger.


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#1 Lt-SilverDragon

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Posted 19 May 2018 - 02:16 PM

Hey all, fitted a supercharger kit that came with my mini last weekend and to say I'm disappointed with the results is an understatement. I know it needs to be set up on a rolling road for maximum performance but because I'll need to travel a long distance to get to one plus everything else I'm trying to get it running well enough that it's acceptable to drive but really there is very little difference in performance between now and before I fitted the charger. There is slightly more oomph esp low down and I'm getting a little bit of torque steer but I wanted overtaking power.

 

Ok the facts, the engine I think hasn't been rebuilt but it is under 40k miles. Compression is slightly low, all 4 are around 110 but within 10% of each other and oil down in each cylinder increases compression by 10-15 on all 4. I'm not sure if my compression gauge might just read low tho as I did a test on another vehicle and it read low as well but she starts fine, doesn't miss a beat and drives fine before and after charger.

 

Engine tune, assume internals and cam are standard for a 93 BOC (1275cc). Fitted 1.5 rockers and adjusted them after I put decompression plate (I know a bodge, if I need to rebuild engine I'll get dish pistons) between head and block. Head is a big valve modified to stage 3 spec I believe. 1.75 LCB and exhaust system, HIF44 carb with BDK needle in it. Tried BCA but way too rich, BDK still goes slightly rich down to about 12:1 on full throttle, Aldon mappable ignition and supercharger is M45 but don't know boost it's pushing.

 

Here's what I've set map at currently, low down pull is not bad but don't want to go crazy with the advance. Think the standard turbo is set to go to 32 degrees?

 

iQqpmt3.png

 

Surely I should be getting decent power out of it, for reference I'd be happy if the acceleration was on par with my 1.9td pug 306 which has 90bhp but is a big fat ass.



#2 KTS

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Posted 19 May 2018 - 04:55 PM

without knowing what boost you're getting it's impossible to say - one scenario is the s/c is delivering just enough boost to compensate for the decompression plate

 

what size is the supercharger pulley ?  someone *may* be able to suggest what boost that should equate to in their s/c setup



#3 Lt-SilverDragon

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Posted 19 May 2018 - 05:14 PM

I'm not sure mate, using a rule it's 65mm but thats from the edge of the lip to the edge of the other lip. I'm planning on fitting a boost gauge soon, there's a bung already fitted on one inlet port after the charger. I just need to find out the thread size so I can order a screw in hose adapter. I never even thought about that, that makes sense. Hopefully it's something as simple as that.



#4 Northernpower

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Posted 19 May 2018 - 05:18 PM

How confident are you on the condition of the cam? Have you measured the lift on all the lobes to make sure none of them are worn? I agree you need to know how much boost you're running.

#5 Lt-SilverDragon

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Posted 19 May 2018 - 06:15 PM

Nope not sure on condition of cam, to be honest I was lead to believe the engine had been rebuilt but I think it was just repainted lol. How do I go about measuring the lift to see if the cam is worn? Is it a case of checking the difference between valve closed and valve fully open?



#6 Northernpower

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Posted 19 May 2018 - 06:46 PM

Nope not sure on condition of cam, to be honest I was lead to believe the engine had been rebuilt but I think it was just repainted lol. How do I go about measuring the lift to see if the cam is worn? Is it a case of checking the difference between valve closed and valve fully open?

Yes just check fully open to fully closed. I would check all the valves to make sure they are opening the same amount. If there is any wear it's unlikely they will have all worn by exactly the same amount.

#7 Lt-SilverDragon

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Posted 28 May 2018 - 11:07 AM

Hi, finally got a chance to look at the mini and measured all the valves and they're all got between 6-8mm (roughly) difference between closed and fully open. I don't own a dti so used a rule so hopefully that's good enough to know how the cam is holding up. Think standard lift is around 6mm? Plus I've got 1.5 rockers, so should be ok?

 

Also what's the best way of installing a boost gauge, on the inlet port after the supercharger there is already a nut welded on and a bolt installed. I've removed the bolt and it's the same thread as the nuts for the cylinder head which I think is 3/8 UNF so for easiest sake I've been looking at bolts with barbed take offs but can't find any in that size. Would this work?


Edited by Lt-SilverDragon, 28 May 2018 - 12:19 PM.


#8 Ethel

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Posted 28 May 2018 - 12:28 PM

Hope you've got your valve clearances proportionally increased for hi lift rockers.

 

The figures sound about right for a standard engine (1.2 rockers), but nothing like accurate enough to be meaningful.

 

I'm not familiar with your Aldon ignition - but there's a boost gauge on your screen grab if you can hook it up while out on the road.



#9 Lt-SilverDragon

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Posted 28 May 2018 - 01:02 PM

I know it's not super accurate but just wanted to get a basic idea if cam was useable the now. Not wanting to pull the engine if possible as I'm needing the mini until I can sort my daily so it was probably a bit of a stupid decision fitting it the now.

My aldon is the vacuum version not the turbo version, think the software is set up for all 3 versions tho.

Set clearences to 15 thou.

#10 DeadSquare

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Posted 28 May 2018 - 04:01 PM

Hi, finally got a chance to look at the mini and measured all the valves and they're all got between 6-8mm (roughly) difference between closed and fully open. I don't own a dti so used a rule so hopefully that's good enough to know how the cam is holding up. Think standard lift is around 6mm? Plus I've got 1.5 rockers, so should be ok?

 

Also what's the best way of installing a boost gauge, on the inlet port after the supercharger there is already a nut welded on and a bolt installed. I've removed the bolt and it's the same thread as the nuts for the cylinder head which I think is 3/8 UNF so for easiest sake I've been looking at bolts with barbed take offs but can't find any in that size. Would this work?

 

 

"Would this work?"     Yes,  always assuming that you can fix the pipe to the boost gauge.



#11 HUBBA.HUBBA

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Posted 28 May 2018 - 08:49 PM

Ditch the 1.5 rockers you need standard 1.3, you need a boost amethyst, advance too high - max 26. Boost gauge off inlet manifold (do you have a picture)

#12 HUBBA.HUBBA

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Posted 28 May 2018 - 08:51 PM

You could also do with an afr gauge

#13 Lt-SilverDragon

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Posted 30 May 2018 - 12:51 PM

If I need the boost version of the Amethyst would I not be better just going megajolt then? because the Amethyst unit is £240 on it's own and that's an awful lot of money just for that. Theres this kit on ebay the now then I could just buy the trigger wheel and bracket off `trigger wheels` and that would give me better control but it would be run off manifold air pressure. Only thing that stopped me going megajolt earlier was sorting out the trigger wheel on the bottom pulley as it's obv a different pulley to the standard mini one.

 

I've got a plx gauge, at the minute it's running slightly rich under acceleration, mixture is about perfect when cruising tho. 



#14 HUBBA.HUBBA

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Posted 31 May 2018 - 08:22 AM

£240? last time I looked it was £150, unless they have just gone up



#15 Lt-SilverDragon

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Posted 31 May 2018 - 11:34 AM

Website and ebay both at 240 mate, I originally got a good deal on the whole package. A series dizzy, amethyst unit and coil. Can't remember how much I paid for it but it was reasonable then I tried to fit it to my a+ series engine and obv the dizzys are different so spent like 180 on getting an a+ series dizzy off aldon.

I'm tempted just to rip the supercharger out and just run NA again if I have to start spending loads on it. Just wanted something that had overtaking potential.




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