355 suspicion
11-05-2009, 01:43 PM
#1
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355 suspicion ok, so a little over a year ago i bought my 93 m6 from a guy in illinios. he took great care of the car, but did not seem to be all that informed when it came to performance knowledge. he said he was the 2nd owner, and the 1st owner had a blower on the car prior to rebuilding it and returning it back to stock in order to sell. he also threw in that it was supposedly bored 30 over, but he had never had it confirmed. i didnt pay much attention to it, especially since i was ignorant to cars at that point. but i always suspected it wasnt stock; it just runs harder then a stock z, including the random ones i have ran. a year later with a little more knowledge, i have begun to suspect i have a 355... like i said i dunno but from what i understand, if it has been bored like he said, then my assumption is correct? im doing a compression test this weekend, any advice on other things to check in order to reach a definate conclusion? please let me know if im way off here... some additional knowledge would be much appreciated, not getting too much from my searches. mods in sig. thanks in advance
11-05-2009, 01:46 PM
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only way to tell would be pull heads and measure bore with a micrometer....
or pull oil pan and do the same..... compression wouldn't tell you crap cause it'll be the same regardless of bore.... and yes if it is bored .030 with a 3.48" stroke crank (stock) then it's a 355....
or pull oil pan and do the same..... compression wouldn't tell you crap cause it'll be the same regardless of bore.... and yes if it is bored .030 with a 3.48" stroke crank (stock) then it's a 355....
11-05-2009, 03:27 PM
#3
A similarly spec'd engine will be the same for a 350 and 355. Opening the cyls up is to clean up the walls correcting scores, ridges, out-of-round etc. Boring isnt done for power output
Most likely the blower cam is still in there since removing that would be more intrusive than simply stripping an air pump or TB
Most likely the blower cam is still in there since removing that would be more intrusive than simply stripping an air pump or TB
11-05-2009, 05:55 PM
#5
So... putting in higher compression 355 pistons wouldn't give him more power?!?!!?
Checking compression would tell him that. If it's the same then obviously the only way to tell is a bore check.
obviously there's no way to check for it being a 355" other than bore check, but it'll tell him about his 'extra power' possibly.
Checking compression would tell him that. If it's the same then obviously the only way to tell is a bore check.
obviously there's no way to check for it being a 355" other than bore check, but it'll tell him about his 'extra power' possibly.
11-05-2009, 06:22 PM
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you wont ever really know what it is untill you pull the heads off and check the pistons for a .o30 stamping. It might pull a bit harder than a stock lt1 if it was rebuilt and/or he swapped pistons to up the compression but highly doubtful.
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11-05-2009, 06:29 PM
#8
Honestly I would bet that if it was rebuilt as a 355 with a blower on it then its probably lower compression, and could possibly be weaker then a stock 355 rebuild.
Just going by the butt dyno is useless, you need to take it to the track or strap it to some rollers to see if anything was done to it.
Just going by the butt dyno is useless, you need to take it to the track or strap it to some rollers to see if anything was done to it.
11-05-2009, 08:50 PM
#9
I would have.
Either way a compression check can possibly tell him something. Not ci but that something could be rebuilt/built.
heads can also raise the compression. so it could show some head work is possible too.
11-06-2009, 12:03 PM
#12
You built a slower 355, therefore his is slower?
Butt dynos mean nothing?
355s mean nothing?
Yeah, I disagree on all parts.
Just cause you built yours a certain way doesn't mean his previous owner did.
Butt dynos mean nothing? They might be minimal and placebo, but he also says his car IS FASTER than other comparable cars.
And a 355 DOES mean something. Cause it could be a high compression or low compression motor. Clearly it's important info to him.
Why is everything about your car? This thread is about his possible 355 and how it may be faster because of how it was built. Stop trying to relate everything to your car.