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Discussion Starter #1
what overbore would give you 3.0L from the stock 2.8L? 0.030, etc?

This '82 i'm getting has had this done, and I want to know as much about everything surrounding it as i can.

I checked the block and it IS in fact a 5m - i say this because i read somewhere else that the 2.8->3.0 is a difficult, if not impossible task.

how big could you go on the 5m-ge?
 

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You'll get nowhere near 3000 cc by over boring the cylinders. If you go to the maximum factory oversize piston +1.5mm you gain about 100cc. You basically go ~2759 cc to ~2860cc. Most any 3L M motor is stroked to gain the displacement. To get you to 3L you would need a ~+3.5mm (+.138") oversize piston. The minimal displacement gains you get from overboring are the reason I only went with +.5mm pistons when I rebuilt my 6M.
 

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Silver Mk2 really have a point here. Now ill cut it out in big letters. The math to calculate the area of a cylinder is r*r*pi*h. 5MGE has a bore/stroke of 83x85mm. this is 2758cc. Boring it out to max. oversize pistons 84,5mm gives you 2858cc a gain of 100cc not much, to say the least. The absolut max. must be 85mm which leaves you with 3mm wall between cylinders, this will give you 2892cc. if you really wanted 3.0 from a std. 5MGE you would have to bore it out to 86,5mm and then theres no cyl. wall left. Now a 6MGE with 85/91mm bore/stroke gives you 3096cc. So you see, theres no point going beyond this.
 

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Discussion Starter #4
then how has the 5m block in the '82 L-type i'm picking up supposedly been bored out to 3.0L, and in addition to this, is there anyway for me to figure out exactly how big the bore is without pulling the entire engine?

the engine in question:


the scary/cool custom header:


//edit: being a relative mkII newbiw (i'm learning fast though...), has that engine had the afm -> maf conversion done to it? or is the other way around that is desirable. i can't remember right now.
 

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K I'm no expert but I can throw some ideas at ya, lol. I'm not saying these are the only things that coulda been done, just a few things that could be the case.

1. the guy bought the car and the guy who had it before him said it was bored out to 3.0 but lied to him.

2. the guy is lying to you and is just saying that to be able to sell the car for more or quicker.

3. maybe he just had the crankshaft, pistons, rods, installed from a 6m to make it a 3.0 and the guy just thinks that's called boring it out.
(does the guy know exactly what he's talking about or did someone else do the work before he owned the car?)

4. the guy had it bored out AND replaced the crankshaft... to make it 3.0+ and just said it was overbored without mentioning the rest.

Those headers are pacesetter I believe, they look just like mine.
and I can't say if the afm -> maf is done as I havn't seen one, but it does look like the sound deadener thing was removed which is why the intake is so short. I can also tell you that that is one huge ass K&N cone filter!!!
 

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Discussion Starter #6
thanks for all the informative replies guys, i really appreciate it!

that air filter sounds really, really cool in the upper rpm range.

the guy BEFORE the current owner did the work, so the guy we're buying from is just repeating what he was told.

My friend has all the paperwork for the car and is going to go through it tonight. My goal was to get in touch with the owner that did all this "work" and figure out what really was done to this car.

Is that pacesetter header any good? is it an improvement over stock?
 

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Big improvement over stock. They are one of only two headers for the MKII. The other being the Doug Thorley. From what I hear the doug thorley is better quality but they are both big improvements over stock.
The only reason I don't like the pacesetter is it's very hard to find a smog tech that will overlook it here in california since it's not CARB approved. Anywhere else that's not a problem though.
Other than that the O2 sensor is in a very bad place unless mounted down lower at the y-pipe.
 

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Discussion Starter #8
the O2 sensor in the supra HAS already been moved, so that problem is solved.
 

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You can check the stroke by removing a spark plug and measuring the distance from TDC to BDC. This will tell you if the stock crankshaft is still installed or if it has been stroked or replaced.
 

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that is a stock flapper type afm. no conversion has been done. all they did was get rid of the intake resonator and blot the afm up higher to an existing bolt hole in the body. ive seen it done several times.
william
 

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Anyone know if there is a noticable advantage to shortening the intake like that? I pulled my resonator and replaced it with a straight 3' pipe - didn't think the length would make a difference.
 

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yes, it will give more power.. but also have hot air blowing from the engine fan when you are running, drastically reducing power.. :evil: and thats a no no :p
 

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gryphon power what are u talking about??? i don't understand what u mean.
 

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I think he meant that shortening the intake pipe length will align the filter with fan more than stock and this will allow the engine to draw in the heated air from the fan(radiator) Especially with a filter that big :shock:
 
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