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Discussion Starter · #1 ·
I'm just throwing out something different. Why can I modify the 5m cam gears to fit the 7m head? That way I don't people don't piss with the crank gear, but they would have to use 5m accessories :( (dam squeky belts)
 

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use the 7m cam gears on the 7m head with the 7m sprocket for the timing belt bored out on the 5m block
 

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kinda a waste of time if you ask me cool but 2.8 L bottom end with a 7m top? and you will no longer have valve relief your better off with a 3.0 L bottom end i would just do a 7mge swap
 

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Discussion Starter · #10 ·
Shit, that's an easier way.

Then I take it people would then run all 7m accessories?

The reason why I don't like the longer stroke of the 7m is because my car is so light.... 78 Cressida with a solid rear.
 

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What's wrong with the longer stroke besides some traction issues? I got the 6M beast in the Celica and I love it and so does anyone that has been for a ride in it.
 

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Here are your options, run a 7m with redline of 6250 rpms and be happy. Or since people have used 7m pulleys for 6m hybrids (7m with 5m head and pistons) it could probably be done in reverse with a 5m pulley on a 7/5m mutant baby (2.8-24v). And the only reason this should be done is to achieve either higher rpms or a closer relationship between bore and stroke. The 2jz has an 85mm stroke which is the same stroke as the 5m crank, however the 2j has an 85mm bore as well. The M series motors have 83.5mm bore which could be changed up to 86mm which I don't think would be safe but 85mm could be ideal for a low comp turbo setup with supporting mods with oil pressure, fuel delivery, mhg that sort of stuff. Really if you are staying N/a go 7mge, if you have a lot of money and time have at the "8mg" idea. In the end the 7m and 5m have the same redline so if your staying N/a the 7m has more torque, more head flow, larger injectors, the list goes on. And the shorter stroke on an 8mge N/a setup wouldn't do much but improve the rod ratio which means less stress on the rods. I am however all for the idea if it is played out right with a ct-26, mhg, 85mm bore and stroke, gte electronics, increased oil pres., increased redline, and the list goes on... It would cost some money though and if done correctly would require a custom pulley. And that's why I said fuck it, 7mge here i come! lol
 

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Discussion Starter · #13 ·
Exactly... traction issues. I don't see how a 7m stroke in a 2400 pound car would be able to do anything but go sideways off the line.
 

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dylan
the 8m was meant to be a high reving motor
thats why i have a daughterboard on a ecu this would put more stress on the rods alot more stress
now the early 7m has a redline of 6500 so in other words you need to be 9k to make the power of a stock 7m unless you spend some serious money it wont work
when i did the math the 8m was meant to rev to 11k
and produce 250 with a ct26
this was a rev monster
axel has this motor in his supra and dynoed it is putting out 252 but it runs out of boost fast so he is curently upgrading the turbo.
it revs fast
ill post a vid
 

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^ (CJ011) bigger tires (preferably less sidewall) and a better suspension setup. And the only way a 7m wouldn't pick up good is if it had too much power for the tire and suspension setup. The 7mge i don't think that will need any tire or susp upgrades anymore than a 5m car would, although I do believe it would be much better than a 5mge. Also if it is a cress get some 14 inch p type rims with 60 series and traction wont be a problem for a while.
 

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dylan
the 8m was meant to be a high reving motor
thats why i have a daughterboard on a ecu this would put more stress on the rods alot more stress
now the early 7m has a redline of 6500 so in other words you need to be 9k to make the power of a stock 7m unless you spend some serious money it wont work
when i did the math the 8m was meant to rev to 11k
and produce 250 with a ct26
this was a rev monster
axel has this motor in his supra and dynoed it is putting out 252 but it runs out of boost fast so he is curently upgrading the turbo.
it revs fast
ill post a vid
11k rpms= BOOM plain and simple
I wouldn't expect a 2j to do that let alone a 5m mutant. The thing is for every 1k rpms gained 10psi oils pressure should be added (for the m series it is not always like that, they are targeted for oil flow specifically). So the thing about high rpm motors is the relationship between oil flow and oil pressure (if it is not considered in a build with high rpms then something will fail).
 

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Discussion Starter · #17 ·
Hmmm... all good points. I say it maybe possible to spin 10-11k on the 7m head with valve train work. Gene Berg spun 9600 rpms over 20 years ago in his flat 4.

Dylan, you do bring up a very important point though about necessary oil pressure.
 

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dylan
in the 8mgte Axel has it makes power till 11k
he is also running a 85 oil pump with a overdrive oil gear :)
it is not impossiable at all it wont go boom either lol

plus my 7m can rev to 8k :) ha ha rev limiter lol thank you daughterboard :)
ive done it too so its not impossiable
 

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Longevity is sacrificed at that point, even if you do a proper setup to withstand 11k rpms the longevity is sacrificed. A part has so many turns, uses, or revolutions before it gives. And if you beat the piss out of it at a rpm range almost double of what the factory set the limit at it will go boom. Not trying to be harsh just realistic.
 

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no your right that type of motor would be good up to 100k then need a rebuild
unless you go all out but im to cheap for that lol
 
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