I know the fully counterweighted 7M crank has a lower factory RPM limit than the 6M crank cars, Does anyone spin their 7M cranks harder than 7000?
*7M Crank RPM Limit*
- Thread starter IJ.
- Start date
4176.66 feet/min piston speed at 7000rpm would be more of a worry then the crank it is sorta pushing it for something reliable!
I've got an opinion, just no real experience with turning high RPM with the 7M. I've put together a few high RPM V8's and a 4G63 so I'm not totally in the dark, I just don't have much experience with the 7M. I'm probably not going to tell you anything new but I'll happily throw my opinion out there if that's what you want. :icon_bigg
I would spin the 7M to 7500 RPM given proper cams and valve springs. A long stroke is what really tears up the rods and the 7M's stroke isn't that bad in the grand scheme of things. A 427 BBC has a longer stroke, a heavier rod and piston assembly and lots of guys are spinning them that fast on factory cranks. That's my .02; let's see if someone who's actually pushing the envelope with the 7M will chime in now...
I would spin the 7M to 7500 RPM given proper cams and valve springs. A long stroke is what really tears up the rods and the 7M's stroke isn't that bad in the grand scheme of things. A 427 BBC has a longer stroke, a heavier rod and piston assembly and lots of guys are spinning them that fast on factory cranks. That's my .02; let's see if someone who's actually pushing the envelope with the 7M will chime in now...
i think joes on the right track here... i believe with the correctly built valvetrain...and obvious supporting mods...the 7m crank can spin fine upwards of 8k...
i personally will most likely be taking a 7m crank and spinning it to about 7500-8k.... it really depends on a few other things im working on and the powerband im looking to achieve....
i personally will most likely be taking a 7m crank and spinning it to about 7500-8k.... it really depends on a few other things im working on and the powerband im looking to achieve....
Thanks Guys!
Good point about the stroke I used to spin my 427 to 6500 routinely and from memory it had a 3.7" stroke with a huge lump of a piston, the 7m is around the 3.5" with by comparison light small piston.
I'm going all Ferera valvetrain so buzzing it shouldn't be a problem.
It's either spin it hard at 22 psi or keep the revs to around 7k and run 26 psi.
Good point about the stroke I used to spin my 427 to 6500 routinely and from memory it had a 3.7" stroke with a huge lump of a piston, the 7m is around the 3.5" with by comparison light small piston.
I'm going all Ferera valvetrain so buzzing it shouldn't be a problem.
It's either spin it hard at 22 psi or keep the revs to around 7k and run 26 psi.
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I think a lot will come down to the head work Allan!
I might take you up on your idea of building a gumby flow bench!
Did you see the dust extractor hooked up to the bead blasting cabinet?
It will be a perfect vac source!
I might take you up on your idea of building a gumby flow bench!
Did you see the dust extractor hooked up to the bead blasting cabinet?
It will be a perfect vac source!
i had a another idea to.. some clear acrylic tube with the same bore ID and we can use some smoke to get an idea of how it flows aswell?? too many ideas not enough money here 
I think that's well beyond the scope of what we can achieve Allan.
I'd be happy being able to baseline a port open it up and see if it flows more or less.
I'm quite happy to poach someone elses research if the data is there but after all it's just a road car I'm building so I'm not chasing every single KW!
I'd be happy being able to baseline a port open it up and see if it flows more or less.
I'm quite happy to poach someone elses research if the data is there but after all it's just a road car I'm building so I'm not chasing every single KW
!I downloaded a vid awhile back I think from memory it's title is "Slowass Mk3" where a red Mk3 with a black hood and black Mk4 wheels is doing a demo and I've never heard a supra rev so cleanly and so hard I'd love to know what's done to it!
<edit> Just Googled it and it turns out it's Genna's Car from 7mpower!
<another edit> I found a working link here it is this thing is AWESOME! (right click save as)
<edit> Just Googled it and it turns out it's Genna's Car from 7mpower!
<another edit> I found a working link here it is this thing is AWESOME! (right click save as)
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Heh, yeah I liked that video as well. You'll need an external wastegate with an atmospheric dump for that type of sound effect.
I'll let you know how 8k works out on my 7M crank, I'm sure it will not be a problem.
I'll let you know how 8k works out on my 7M crank, I'm sure it will not be a problem.
i love genna's supe. or old one.. didnt that one get sold? oh well.
anyway:
isnt that a mkiv hyper medallion exhaust?
and why would the wastegate dump have to do with the exhaust note? i understand the full boost noise, but not the exhaust note. it's very mkiv-ish in itself...
anyway, yeah.
woo hoo 8krpm 7m
i want to hit 9. not all the time, but be able to. lighten the rotating assembly, i could de-stroke it, but that's just not fun enough. i want 3 liters of 9k fun. i'd say it's doable. i havent thought real seriously about it as only considering it makes my bank call me at night wondering what i'm planning... if im going to really look into it, i still need to calculate piston speed and so forth, so on... blah blah. right.
anyway:
isnt that a mkiv hyper medallion exhaust?
and why would the wastegate dump have to do with the exhaust note? i understand the full boost noise, but not the exhaust note. it's very mkiv-ish in itself...
anyway, yeah.
woo hoo 8krpm 7m
i want to hit 9. not all the time, but be able to. lighten the rotating assembly, i could de-stroke it, but that's just not fun enough. i want 3 liters of 9k fun. i'd say it's doable. i havent thought real seriously about it as only considering it makes my bank call me at night wondering what i'm planning... if im going to really look into it, i still need to calculate piston speed and so forth, so on... blah blah. right.
supra90turbo said:
An external wastegate vents high pressure pre turbo exhaust gas driectly to atmosphere. It doesn't really matter what muffler you have on the car when the wastegate dump is open, wich it was for most of that video.
Kurt: Ohhhh big $ to go to 9k!! (I'm fairly comfortable with the idea of 8k but man 9 takes some doing)
If you do get there a video is compulsory!
Brian: Didn't realise it was dumping to atmosphere! (now I know this it seems reasonably quiet!)
Everyone else: If you haven't grabbed this Vid do so as an example of a well tuned 7M it's a beautiful noise! (first time I heard it I thought "ohhh welll not bad for a 2JZ")
If you do get there a video is compulsory
!Brian: Didn't realise it was dumping to atmosphere! (now I know this it seems reasonably quiet!)
Everyone else: If you haven't grabbed this Vid do so as an example of a well tuned 7M it's a beautiful noise! (first time I heard it I thought "ohhh welll not bad for a 2JZ")
Bit of an update to this thread now I have some time with my 7M crank!
I can state here without a doubt that at 6000 rpm the 7M crank is smoother then the 6M crank.
I'll update as I raise the limit on my motor!
I can state here without a doubt that at 6000 rpm the 7M crank is smoother then the 6M crank.
I'll update as I raise the limit on my motor!
I have full 3 inch from turbo and MANY other mods but running stock cams and turbo and mine hits HARD at 3-5 but it looses power high up there in the RPM band so I shift early like 5 1/2 - 6. If I wento 7,500 my car would slow down alot
Mine's built to spin safely to 8000 so this gives me a nice broad powerband from 3000>8000 and the motor still has good torque and response below 3000 off boost so I'm pretty happy!
A CT upgrade will fix that problem Porterz
Back from the dead, eh Ian? lol.. I never noticed where you replied up there to get videos if I go 9krpm... yeah..
I am putting shimless buckets on, and adding Ross pistons and possibly eagle rods... I'd like to get Pauter, but $1000 for rods isnt where I'm at right now.
I think I'll easily graze 8krpm, if not 8.5krpm. What do you think?
Back from the dead, eh Ian? lol.. I never noticed where you replied up there to get videos if I go 9krpm... yeah..
I am putting shimless buckets on, and adding Ross pistons and possibly eagle rods... I'd like to get Pauter, but $1000 for rods isnt where I'm at right now.
I think I'll easily graze 8krpm, if not 8.5krpm. What do you think?