Man with spanners - thinks he's a mechanic

Need help from a fellow owner, something to air - discuss away!

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DJ.
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Re: Man with spanners - thinks he's a mechanic

Postby DJ. » Tue Sep 15, 2020 2:07 pm

Brilliant :mrgreen:

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ChrisL
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Re: Man with spanners - thinks he's a mechanic

Postby ChrisL » Wed Sep 16, 2020 7:12 am

Thanks Duncan
Mark it's a good question, currently suffering from procrastination paralysis!
The engine has a 1.5mm decomp plate and two 0.6mm head gaskets. I'm using the 9 PSI pulley and so far not taken the engine over 3000 RPM and a boost of 4.6 PSI. The pressure test has all of the cylinders reading between 70-80 PSI, which fist with having the decomp plate in there. Also have fitted a knock sense which needs calibrating as it's over sensitive atm.
So what to do? I'm feeling like getting a professional tuner to tune the engine and configure the knock sense, so at least I have some insurance i.e. if the charge cooler leaks and my inlet temps go too high. But the question is which pulley, the bigger one produces 12 PSI and i feel that with the decomp plate that should be fine but will it be, I don't want to take it to the tuners and come back with it blown but conversely I'd like to get the most bang for my buck (without ending up with a prima donna of an engine)? The other factor is I have an MOT due in October and I'd like to be able to keep the car on the road.

Currently modifying the 12PSI pulley to take the interchangeable pulley system I'd built for the 9 PSI, at least then I can go to the tuners with both options (probably with the 12 PSI fitted) and see what they think, or drop down if it's generating too much boost as neither puller has ever been run at 7000 RPM, although I think that SCs tend to have a linier boost profile I'm not 100% sure...

What I will say is I've really appreciated all of the advice received and happily accept that it is just advice :-) Also I'm enjoying learning, not just about engines but having lots of fun with the TIG but I would like to make a tour next year!
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ChrisL
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Re: Man with spanners - thinks he's a mechanic

Postby ChrisL » Sun Sep 20, 2020 2:16 pm

So the good news: I've been out and had a play and I still have 4 cylinders with pressure!
Tune seems to be coming along but still am planning to use a dyno but I've done enough to pass the MOT next month.

The bad news is even with the bigger *edit - that's smaller obvs* pulley I seem to only be making 9 psi of boost. I don't know if this means there's an issue/leak/belt slipping or it's some kind on volumetric limit caused by the decomp plate - bit of googling in order....
Last edited by ChrisL on Thu Sep 24, 2020 10:16 am, edited 1 time in total.
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SteveRST
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Re: Man with spanners - thinks he's a mechanic

Postby SteveRST » Wed Sep 23, 2020 7:41 pm

Good work Chris!

I believe that superchargers build boost in a linear way as engine revs rise.
So how does the bigger pulley build boost compared to the small? Does it plateau and not build boost further? How many revs you going to?

I'd say 12 psi will be ok as long as the tune is good, so take it easy and watch those datalogs!
Mine was running 12psi but I had 3mm decomp plate compared to your 1.5mm
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ChrisL
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Re: Man with spanners - thinks he's a mechanic

Postby ChrisL » Thu Sep 24, 2020 10:47 am

Got my sizes the wrong way round in that I'm now running the original smaller pulley which should generate more boost. Below is a comparison between last year and now, both seem to reach peak boost at 3000ish rpm. More investigation needed

Current:
now2.png


Last year:
last year.png
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ChrisL
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Re: Man with spanners - thinks he's a mechanic

Postby ChrisL » Sat Sep 26, 2020 11:35 am

Just a quick update but went out this morning and did some more tuning. All good so far, I’ll need to look at the graphs and at some point swap in my spare supercharger as this one has an oil leak on a seal that can’t be replaced, but it’ll do for now
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ChrisL
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Re: Man with spanners - thinks he's a mechanic

Postby ChrisL » Wed Oct 14, 2020 7:46 pm

Car’s past its MOT! And still seems to be working. I’ve swapped the chargers over ready to put some more miles on. The rain had got me thinking about air filter placement, as you do! The problem is that my air filter sits just in front of the driver’s side firewall, and just pokes out under the car. It’s a big ramair cone filter connected to an elbow that connects to the SC inlet. The pics below hint at the location. My concern is water, when I drive over some puddles I often end up with wet feet where the water has come over the firewall (no peddle box cover) which it exactly where the air filter is, so am I going to have dry feet at the expense of sucking water into the charger? Or am I just over thinking it? I know that there are some cars with low mounted filters or exposed high mounted ones so what’s the thinking/logic? Has anyone had any issues?
7D4F8419-7962-4894-84A2-413107004342.jpeg

3C2B7C9B-C714-462F-8B6F-9E3B16B55E74.jpeg
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Tony C
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Re: Man with spanners - thinks he's a mechanic

Postby Tony C » Thu Oct 15, 2020 8:23 pm

Chris, I can't comment one your supercharger set up the complexity of it lost me some time back, I struggled to set the timing on the Sprite :oops: I think the filter looks a touch low knowing some of the roads that an SKCC run can involve, how easy would it be to move it higher up? Good luck with finessing the engine set up.
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ChrisL
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Re: Man with spanners - thinks he's a mechanic

Postby ChrisL » Fri Oct 16, 2020 9:18 am

Thanks Tony,
It's probably about the same height as the sump, but you are right moving it up would take it out of the firing line!
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Re: Man with spanners - thinks he's a mechanic

Postby kenton » Fri Oct 16, 2020 5:04 pm

That location would worry me.
How about coming through the side panel with some sort of a cowling over it.
A bit Mad Max like. :lol:


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