Kevin -

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Your boost level is in a range that I dont think you need the oilers.


I agree.

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Ok ... you did melt a piston, however once you get detonation any piston will melt.


I'm not yet certain that I did since I haven't pulled the head - but there was enough detonation to blow the head gasket and at least SOME damage was done to the last piston in the fuel rail order or I wouldn't have found aluminum specs on the #6 plug. My concern that I holed a piston was because the sump was pressurized after detonation - I s'pose it could be only a blown gasket, but I won't know until I tear it down.... won't be long until I get a look at the damage.

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There is nothing that will keep a piston that is in prolonged detonation from melting. Forged will help since they transmit heat better.


I agree - and I have the machine shop looking for forged piston options. For the amount of boost, I consider forged pistons overkill, but worth serious consideration - particularly if I try to go beyond 7 psi to the blower limit. Another option might be coating the pistons - my choice between only the two is forged - particularly if they're custom CR.

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Get a compression ratio that gets the cyl pressures in a decent range, use some type of boost retard on the ignition, get a plug thats not too hot under boost and make sure the fuel supply is there and you won't have any melted pistons.


Yep - as stated, pistons are being searched now, MS2 includes full spark map control w/boost ignition retard as desired, plugs will be 1 or 2 ranges colder than stock and the fuel rails have been reworked for dual feed/constant pressure.... and will include larger injectors needed to run at the constant fuel pressure.

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If you could get a detonation sensor that dropped the timing back that would help a lot if somthing goes wrong like you get an unexpected lean out.


That's why I hope to be able to use the Diamante block - it has the detonation sensor mounting plate - not the best arrangement compared to a direct mount to the block, but I don't see a good place to mount a sensor directly on the 3.0L block. I plan to use a GM sensor on that plate - it'll connect to a Knocksense translator:

Knocksense

Using that unit for a signal (or I can build a unit onto the MS board) MS2 has the capability to further retard the ignition on knock detection and sneak back up to knock threshold if desired.

Brian -

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If you are going to be building a forged motor you do not need oil squirter's. There only really needed for cast pistons.


I agree, but forged do give a small amount of safety margin. I don't particularly like forged pistons - or their cost - but I'm interested in dropping the CR back to maybe 8.5:1. The cast 8.9:1 pistons are ok, too - if I don't put more than 7 psi on it - just trying to get the most bang for the buck and leave a little headroom if I want to try to max out the blower (which I haven't yet done).

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The nice thing about not having oil squirter's is you then get more oil to the main and rod bearings. And the cams.


I agree - if the squirters were designed for the block - and IF the oil pump was designed for the application combination, I'd use them..... but I don't want to be on the leading edge of that experiment.

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I was reading on here that some one said that 20-24degs of timing would take out your rod bearings. Not true. Knock is what takes out your rod bearings, or bends a rod. In my Galant vr4, I run 28-32psi of boost(turbo is a gt30r) depending on track prep with a max timing of 23degs. Never once, have I had a bearing go bad, From to much timing.
Once you get the rig up and running and you have a nice engine management system that can read knock. Get a good base line tune. Then from there set you boost that you would like to run. If the engine is not knocking start adding timing in tell you see knock. Once you see knock stop and take out a deg of timing tell knock goes away.


I have no idea how much spark lead I can use until I start tuning, but I *think* the prior problem was a fuel issue. I'll give it whatever spark lead it wants... the main issue may be finding a good dyno to use. I'd like to find a steady-state dyno, but will probably have to trailer the truck to somewhere around Charlotte Motor Speedway to find a good shop.

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Oh and if using megasquirt take your time on the tuning. I have see a lot of people kill there engine using them. Most all the the cars I have see blow up using megasquirt was because the people got the kit and did all the soldering of the boards there selfs.


Thanks for the warning - I did do all of the PCB soldering myself - hopefully it's ok..... seems so on the stimulator.... so far. I do plan to take my time, though.... there's a lot about MS2 I don't yet know.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum