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Chris,

I don't know if Richard Jemison is still providing them, but my clutch was put together by Richard. Hockey puck style with solid disc. Less rotating weight, and has worked great for several years of autocross.
 

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Discussion Starter #82
Well made points Bill - I do value Greg's input to this as he is the guy with all the knowledge and experience.

I am troubled as to why boost is so far off the expected level so will be looking closely for leaks before getting carried away with small pulleys. I would much rather find a leak and get the boost I want that way than have to muck about re-jigging everything for a smaller pulley.

Ensuring the bypass valve was absolutley tight shut made no discernable difference to the boost. Now it wasn't open much, but I did expect some change. Having said that, I also fixed the cam timing error as well, so that will have had some effect. Just can't figure out quite what!

I got some T-bar clips for the big hoses and will fit them tomorrow. I will tighten up all the water nozzles and will use some thread seal on them as well for good measure. More difficult areas to check are the inlet runner couplings and the runner to inlet manifold joints as well. However, I did use sealant on those.

I'll see if I can rig a pressure feed to the inlet to test for leaks as well - that's a lot kinder than revving the nuts off the thing while looking for bubbles! I should be able to pump air into the inlet side by taking off the IACV coupling and pumping in there.

I'll post up more when I have some news - good or bad as ever!
 

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It'll be nice to see some video of your car going all out some day. I would just add that your water injection pump should supply enough pressure to overcome the boost in the manifold. Each nozzle should have a one-way check valve as well...

I don't know what kind of fuel you have available, but Bill makes a really good point (esp. w/such high static compression) Turbo and Supercharged Engine Compression Ratio Calculator Racing fuel is good insurance till you get the water injection working right.
 

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Discussion Starter #84
WI pump works at over 100psi (more like 150), and there is a check valve before the manifold...but it's not really needed to prevent water being drawn in as I'm using the HSV so those are covered...but good thought! Conceivably there could be some movement of air between cylinders via the nozzles and water manifold. Interesting point now I come to think on it. Quick check would be to blank off the nozzles and see what difference that makes.

Re leaks - made up a coupler and manage to get the best part of 1 bar pressure in it. There were a few bubbles from a couple of the plenum/runner couplers that succumbed to tightening the clips (the T bolt ones by the way - the much maligned Jubilee style clips didn't leak at all!). Also got some bubbles from a couple of the spray nozzles as I thought I might - sealed these with some PTFE tape and a bit more effort on the spanner. All other joints tight and bubble-free.

Haven't done a test run yet to see if this has helped boost at all. If it doesn't, then it's time for that smaller pulley.

Keep the ideas coming guys - always welcome anything that makes me think twice!
 

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Discussion Starter #86
Well, another test run this morning on the way to work after finding those small leaks. Cold, damp day, gained maybe 0.3psi over figures from the RR. Given the ambient conditions, I'd say that's no difference at all.

I'm pretty certain now that the problem lies with the blower itself - it's just not that efficient and i thikn it's suffering a lot of slip. Obviously, a shiny new MP62 would work well.....

Smaller pulley here we come.
 

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Discussion Starter #87
Must stop posting the same story all over the place...I lose track of which pages I've updated....

...anyway...mystery solved on the relative lack of boost - the blower is FUBAR. Didn't spot it before, but I had it apart to replace a broken bolt and found the insides scored to blazes. Like trying to pump air with a rake!!

Short-term I'll spin it faster to make sure the rest of the system works OK with 7-8psi. If so, I'll look at getting a refurbished unit from Embree (thanks Greg!).

More anon when I get the hub for the modular pulley and can start playing with drive ratios.
 

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Hi Chris,

Sorry to hear about the blower. That's one of the problems with using an older unit. On the plus side Embree can make it like new again but in your case due to the cost of two way shipping it probably makes more sense to just buy a refurbished unit from them.

Good Luck,
Greg
 

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Hi Chris,

Sorry to hear about the blower. That's one of the problems with using an older unit. On the plus side Embree can make it like new again but in your case due to the cost of two way shipping it probably makes more sense to just buy a refurbished unit from them.

Good Luck,
Greg
 

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Discussion Starter #90
Can't say you didn't warn me Greg, but I'd already taken the pre-enjoyed path before we 'met'. I'd certainly second that advice for anyone else considering this though - buy a new unit or a refurb from Embree.
 

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Discussion Starter #91
It's been a while...

Fitted a smaller pulley and got 8psi...which felt pretty strong even with a very safe map in the ECU. A UK car magazine wanted to do a feature on the car, but it embarrassed me and blew a head gasket on the day. Thankfully we'd already finished the photo shoot. At least I got some stunning pictures of the car out of the day.

I'm pretty sure it was just down to a poor quality gasket, but I'm unwilling to risk it supercharged again so have returned the car to aspirated configuration for now.

Longer term, I plan on doing it properly! I'll build another engine specifically for supercharging. A set of Greg's LC pistons, a blower overhauled by Embree and somewhere between 10 and 14psi of boost. I'm hoping funds will allow me to get going on this in a month or two. Meanwhile, I'm driving around missing all that extra grunt.

Hopefully there will be a happy ending here one day....
 

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Head gasket and supercharger

I've expected my supercharged 3 liter to blow a head gasket (I'm running 8 psi with 10.0 to 1 pistons, on 112 octane race fuel), but gaskets have lasted for 3 years now of solo racing.

I agree--if you are driving on highway then you should have engine built just for forced induction, with lower compression. Will allow you to use "pump gas" and still get plenty of power with even more boost.

My setup gives me lots of mid-range torque, which is ideal for solo racing/autocross, which is why I didn't go for the lower compression. Plus I don't use that much race fuel per event. :)
 

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Discussion Starter #93
I'm pretty sure it was just the cheap nasty ebay special gaskets to blame...and me for using them of course. Some of the fire rings where a bit 'puckered' in places which might suggest poor contruction? Dunno really. I used some Goetze gaskets for the rebuild and these looked a whole lot nicer. It would probably be fine now...but I don't want to chance it. The engine still wants a re-map whichever supercharged spec I go for, so I reasoned I may as well get everything right and do it once (well, twice). The blower itself is in very poor condition as well, so is losing boost and wasting power.
 

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Richard Jemison
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preventing firering migration

If you are building a motor that you know might experience high cylinder pressure (or detonation:rolleyes::eek:) that could cause firering migration, there is a simple solution that I have used for over 45 years, and has been in use by Alfa racers far longer than that.:cool:
CAS reccommended doing both Head and liners but liners are enough to lock gasket in place.
I agree that it is best to do both. Grooving both prevent gasses from blowing past and erroding the head surface.
 

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Richard Jemison
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O-ringing

O-Ring machining requiries precise cutting of both machine grooves shapes, depths, and positions in liners and heads. Fine with cast Iron blocks, not so with liners.
The Wire "O" rings as well have to be exactly cut from stainless wire the right diameter for the grooves made. If you get it right, great. If not you get short life(blow through). For drag cars that is no problem. They are apart daily or weekly generally.
They WILL hold more pressure. But far more work to get right.
For playing with street boosting I would think "V" groving the liners would do the job unless idiots:eek: are involved.:p

Rest of the problem is gaskets now seem to have smaller firerings than "back in the day". You have to be sure to mark where you want to cut the "V" groove to be sure to catch the last of the metal. Not much there anymore.
 

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Discussion Starter #97
Thank you for this Richard. I asked about grooves in the liner tops a short while back following a suggestion from a firend on the topic, and Gordon Raymond came back with a suggestion of a parallel sided cut of about 0.5mm deep and 0.8mm wide, but I can see a V groove would be a bit easier to machine, and to my untrained thinking at least, feels like a better thing to be asking the fire ring to be deforming into.

Bearing in mind that idiots are involved (me), could you clarify for me just where the groove needs to go in relation to the fire ring please? A rough idea of ideal dimensions would be a great help too please. I can pass these to the machinist (or possibly Greg as he is going to be supplying the liners for me).

Many thanks.
 

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Thanks Richard. That's really good information. I have never o-ringed an Alfa engine, but I did have a souped up Dodge Challenger with a 1957 392 Hemi with o-ringed heads. It worked well, but it didn't really have that much power in terms of horsepower/liter anyway (probably about 400-450hp), so it wasn't exactly a good test case.

Greg Gordon,
HI Performance Store, Inc
 

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Discussion Starter #99
FWIW, the friend of mine that first put me on to the idea had this done on a twin-turbo Alfa V6 that was at one point making well in excess of 400bhp. It had assorted issues during it's development but never head gasket problems. Final issue it suffered was a total loss to fire :(

I did get the crankshaft & rods from it though.
 

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Discussion Starter #100 (Edited)
Well, bit of an update on this project. I decided to have another go, but do it properly, so opted for a set of 8.8:1 Venolia pistons from Greg G, a pair of cams custom-made by Richard J, a bit of DIY valve and seat work by me to Richard's recipe, a re-worked blower which will hopefully give me better boost than the old knackered one, a full engine balance by Vibration Free and a general refresh of everything else in the motor.

It took me a while, for a number of reasons(!), but I've finally managed to actually drive it with the new motor, albeit in aspirated form for now. I took it out yesterday to bed the rings and with my badly calibrated Derriere Dyno, I'd be hard put to say it feels much different to the previous 10:1 motor really. If anything, this one feels as if it revs better, in that it doesn't run out of puff like it did before. Could simply be it has a flatter torque curve, but Richard did promise me good off-boost performance, and he wasn't telling fibs! Can't get much more off-boost than not having the blower installed. Greg also chose 8.8:1 for the same reason of good off-boost performance, so credit goes to Greg too. I've built a new exhaust for it with 24V headers, 2" secondaries and 2 1/2" cans, so that's another factor.

So far so good...hopefully, the next update will be after another RR session and I'll have a good set of numbers to report.

Next step is to put a few miles on it, then re-torque the heads and reassemble the top-end with the blower. The layout of the car meant I couldn't face installing the blower etc just to pull it all off again a week or two later just to do the re-torque.
 

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