bi22le
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| posted on 3/9/13 at 10:13 PM |
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4age advice (or any engine I guess) 1bar boost and 11:1 CR
Im working on more power and thinking about supercharging my BT with an Eaton M45 supercharger that will push max boost 1 bar (14PSI). I am going to
put in the latest 4age large port rods and keep the pistons. Therefore I get the strength of prooven 300hp engines and keep the CR of 11:1. I have
Omex 710 ECU, engine has a knock sensor.
What im asking is, with 11:1 CR and 1 bar boost with high (101) octance fuel do you think my engine will be able to get a usable map? What are your
thoughts on potential floors and things to plan for. I am hoping for 250hp+.
Its a budget build so no aftermarket stuff here. Im keeping the BT pistons but am thinking on getting them ceramic coated, P+P the head DIY if it
looks like its needed. Fabricate everything else.
any thoughts or ideas welcome.
Bizz
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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mark chandler
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| posted on 3/9/13 at 10:34 PM |
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A big intercooler will be a must, my blade engine is supposed to be 12.3:1 ratio running 7psi without issue.
The camshaft has a big influence as 11:1 is simple volume measurement as the valves close after the compression stroke has started the reality is less
so have a good google to see where the cams need to be optimised.
Corky bells book is available on-line for free in PDF form, have a read.
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luke2152
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| posted on 3/9/13 at 10:40 PM |
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I'm no expert but would have thought 11:1 is way too high for 1 bar boost - maybe with a huge intercooler
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bi22le
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| posted on 3/9/13 at 10:59 PM |
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Intercoolers produce lower inlet temps as do meth and aquamist style systems. Your correct in thinking this needs to be addressed.
Anything else?
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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Nickp
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| posted on 4/9/13 at 06:00 AM |
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Sounds like a recipe for immense cylinder pressures!!  Is there a seriously strong head gasket and HD head bolts available?
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Bare
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| posted on 4/9/13 at 07:02 AM |
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Boost is sooo addictive.
But it's a lot harder to setup ..well ...than folklore might suggest.
Your pore engine "might' handle 10 or 11 psi with 11:1 comp... or it could very quickly hole it's pistons under detonation.
Detonation is the enemy followed by heat dissipation issues.
I wouldn't even attempt that without an EGT sensor... at least.
Yes an Intercooler Helps.. some... But it's needing a big Efficient one and likely even water/injection
Presumably you already have Piston oilers ifitted??
Boost is unforgiving of misjudgements :-)
WOT for 60 seconds will Destroy ...any... 'not right' setup.
G luck
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richardm6994
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| posted on 4/9/13 at 07:36 AM |
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Mine is a different project but we can draw some similarities and here is what I've learnt from the m45 onto mx5 engine that I'm currently
doing for a friend's roadrunner SR2....
IMO 14psi is too much boost to expect from the m45 supercharger given it's pulley size.....m45's are good for 6-7 psi and anything over
that and you're over working them! You can put a smaller pulley on them to increase boost slightly but to get up to 14psi the internals will be
spinning way faster than designed....needle bearing in the rear will be first to fail and then the compressor rotors will start hitting each other as
they spin.
If you want 14psi, then maybe consider using a bigger supercharger like the m62.
I also think your compression ratio is too high to begin if you want 14psi boost....just a gut feeling.......but should be ok with 6-7 psi given the
correct mapping.
On my set up, I will be adding an additional thottle body in front of the supercharger to smooth out idle / low revs. I will also be using the mini
bypass valve to improve acceleration from low rpm.
And obviously I'm going to use an intercooler.
Finally, the supercharger I'm using is an M65....which is the same as M45 but is used on the mercs (not the bmw minis) so it doesn't have
the water pump take-off and it also has a different inlet and outlet patterns.....but the restof the charger the same.
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mark chandler
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| posted on 4/9/13 at 09:28 AM |
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The m90 on my DB7 just has a TB infront of the s/c, the outlet goes through a air to water intercooler then straight into engine.
I spent quite a bit if time porting it, genIII charger which has made it quite a bit faster.
It also runs as standard quite a high boost 14psi I think with an 8:1 compression ratio.
As above, with 11:1 I think 14psi is to much as you will need a small pulley to achieve this, your engine revs high so you will be in the danger zone,
better to aim for maybe 8psi in the first instance, you should still hit your target 250bhp.
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jeffw
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| posted on 4/9/13 at 09:31 AM |
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I run aroun 1bar and 10.5:1 on forged rods and pistons. The primary difference is where the max boost is made on a Rotrex install compared with a
normal supercharger (or turbo).
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bi22le
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| posted on 4/9/13 at 10:34 AM |
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Cheers for your thoughts. My searching suggested that max boost from an M45 was 1 bar hence why that is my target boost.
A larger charger is an option but as they are designed for larger engines I was unsure how it would match up with only a 1.6L.
I am aware of the merc alturnative Nd may end up with one in the end.
I can change the CR with ease as I just need to select the right pistons. All 4age pistons fit my engine.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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Pete Jordan
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| posted on 4/9/13 at 12:21 PM |
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Have you checked out Bill Sherwood's 4AGE tuning pages? He seems to have done a lot of 4AGE tuning including supercharging. He reckons that a
suitable engine ie 4AGZE (the supercharged engine) with 260 degree cams and 14psi of boost should be capable of 300bhp!
Here's a link: Billzilla 4AGE pages
I contacted him some time back and he sent me a 3D ignition map, which I think was for a supercharged 4AGE. Will have a look and see if I can find it
if you like.
Either way, I found his pages really useful for all things tuning on a 4AGE.
Pete
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richardm6994
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| posted on 4/9/13 at 01:05 PM |
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quote:
Originally posted by bi22le
I am aware of the merc alturnative Nd may end up with one in the end.
Just be aware that to customise your intake pipe on the m65 is a right pain in the ar3e. I've had to do a lot of machining to the supercharger
body to make it fit exactly how I want it.
The mini M45 looks to be easier to use in a conversion and it's probably the one I'd choose out of the two.
I would be cautious about running the m45 (or 65) at 14 psi as they would be spinning so fast that the standard needle bearings in the rear would fail
after a few thousand miles. I believe there is an upgrade "heavey duty" bearings you can buy so that you can spin the charger faster
(probably where you've heard 14psi from), but to fit these you have to machine the supercharger as they have a bigger OD than the originals.
[Edited on 4/9/13 by richardm6994]
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turbodisplay
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| posted on 4/9/13 at 08:34 PM |
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What I would do is use a larger supercharger, possibly a chargecooler rather than an intercooler for packaging reasons.
I don`t know if the omex can activate an output if knock is too high, but if so, use it to lower boost to 5 - 7 psi via a bypass valve.
Darren
Forgot to add - my GT4 has a knock sensor, to retard ignition, severe knock results in boost reduction. Also reduces boost in gears 1 and 2, as well
as when coolant is cold.
[Edited on 4/9/13 by turbodisplay]
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bi22le
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| posted on 4/9/13 at 09:25 PM |
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Cheers for your thoughts. Im thinking there are 2 options.
M45 with max 7psi
M62 with more boost and lower CR.
Its not happening to soon. Im going to do more research while i gather the pennies, and guts!!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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Nickp
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| posted on 5/9/13 at 05:52 AM |
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quote:
Originally posted by bi22le
I can change the CR with ease as I just need to select the right pistons. All 4age pistons fit my engine.
If you have the option then definitely go for pistons that'll give you a lower CR, maybe 8 or 9:1 if possible? That should give you much more
scope to wind the boost up later if you do get the bigger supercharger on there.
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