5m crank in a 7m, or just go 5m?

[bigaaron]

I just picked a 5m longblock today! Thanks Dan :thumbup:
It had rod knock suddenly at startup one morning and was only driven a very short distance after that. I'm hoping that the crank and rods are ok.

I have been pondering a destroked 7m for a good long while now :naughty:

After taking a good look at the 5m with Jose we were thinking, why not just use the whole 5m? The 5m head looks to me like it could possibly outflow a 7m head. There are no shims to pop out, so I could probably rev it to the moon with a nice set of valve springs, and that spring set would cost a whole lot less since there are only 12 valves. I would use forged pistons and rods.
The 7m exhaust manifold fits the 5m head. I would use a custom FFI. I have the standalone and gt4082 turbo setup already. The 5m can use 7m ARP head studs too.

Now bear in mind that the goal with this engine would be something like an "oldschool 1j". Not for drag racing and not for 700whp. A solid 425whp would be plenty. I want to stick to the M series, but also do something different that oldschool Toyota guys would trip out on.

The origional plan was to put the 5m crank in the 7m and modify or make a custom crank pulley, with forged pistons and rods. That still could be a possibility.

Maybe i'm crazy, but it would be a fun project reguardless. Anyone have any good input about the 5m to share?

(btw, if you don't understand why in the hell anyone would ever want to do this please don't respond :biglaugh: )

 

[ma71supraturbo]

I'd like to see a 5m crank with 7m pistons & head... The 5M head doesn't flow that well at higher rpm and you're giving up low-end power by taking away some displacement...

 

[bigaaron]

I'd like to see a 5m crank with 7m pistons & head... The 5M head doesn't flow that well at higher rpm and you're giving up low-end power by taking away some displacement...

How about if it had oversized valves in the 5m head? Do you think that would help much? If I used my .029" over 7m pistons with the 5m crank and 7m head it would proably be around 2.85L, not too much lost.

 

[Big Wang Bandit]

I unno if that would make up for the lack of 12 Valves.

 

[bigaaron]

I unno if that would make up for the lack of 12 Valves.

The valves are huge! Lots of V8 engines have 2 valves per cylinder and make huge hp, yes?

 

[Big Wang Bandit]

Well if they are HUGE HUGE, It may work. Ignore me, Your the expert

 

[bigaaron]

Well if they are HUGE HUGE, It may work. Ignore me, Your the expert

I'm no 5m expert, that's why I'm asking. I do appreciate your input, you had a great question.

 

[Tanya]

the 5M head vs 7M head "flow" has been argued back and forth over for YEARS, and I'm sure there's some datasheet somewhere that proves the 7M head totally outflows the 5M regardless of oversized valves or not.

Using the 5M head is more of a personal preference I think. Something odd and cool about pulling decent HP numbers out of a outdated configuration, which is why I am diehard about staying n/a.

I also think the 5M head, cam towers, valve covers look so much better than the 7M for some reason, always have, always will.

 

[ma71supraturbo]

The valves are huge! Lots of V8 engines have 2 valves per cylinder and make huge hp, yes?

Yes, they also have 5.7 liters or more... Draw a large circle on a peice of paper. Then draw two circles that are just big enough to fit inside that circle. Measure the area of those two circles. Then copy the large circle and draw 4 circles that fill it. Measure their combined area. You'll find that the multiple valves have more area (and therefore should flow better).

But not only that, but a 4-valve head also mixes the air/fuel better (and fills the cylinder more evenly) so you get more power even if the same amount of air/fuel gets in...

 

[bigaaron]

the 5M head vs 7M head "flow" has been argued back and forth over for YEARS, and I'm sure there's some datasheet somewhere that proves the 7M head totally outflows the 5M regardless of oversized valves or not.

I'm sure you are right, and we don't want a "7m vs 1j" type thing here, but if it would be very close in performance then that would justify it to me.

....Something odd and cool about pulling decent HP numbers out of a outdated configuration....

I'm totally with you on that!

 

[Nick M]

I remember the HKS 5M car. With two turbos and a lot of boost it only laid down 250rwhp. The heads just don't flow enough air.

I also think better to simply run the destroked 7M. If that is what you want.

 

[Big Wang Bandit]

I think Ma17Supraturbo hit it on the head, Big 2v V8's make that much HP cause they have massive ammountsof displacement, Our little engines make up for huge displacement by technology.

I say try to keep a 4v setup .

 

[williamb82]

7m and 5m heads stock flow similar. i have os valves for my 5m and 7m heads im working on. though both heads have been ported as well. when they are done ill try to have them flowed so we can settle the debate once and for all.

 

[Tanya]

I remember the HKS 5M car. With two turbos and a lot of boost it only laid down 250rwhp. The heads just don't flow enough air.

I also think better to simply run the destroked 7M. If that is what you want.

How about this HKS Mk2 eh? :evil2:

If you're talking about this HKS mk2
http://www.celicasupra.com/media86.htm

then blah, I say, BLAH! The bolt on kit kinda sucked, same with the Spearco
but todays technology is so much better than it was in 1986 and big HP 5Ms are totally doable.

Take a look at our top turbo'd timeslips and see what's #1
Turbo/Nitrous/Supercharger/V8 Drag Times
1.Jody Sille_____ <5MGT/M>(86) 10.669 @ 126.0 mphTimeslip
2.Damon Saul___<7MGT/M>(81) 12.225 @ 116.5 mphTimeslip
3.Donnie Spears_<6MGT/M>(85) 12.237 @ 112.6 mphTimeslip
4.Pituala_____<1JZGTE/M>(85) 12.685 @ 111.7 mphTimeslip
5.Jason Moorman<6MGT/M>(85) 12.862 @ 110.4 mphTimeslip
6.Joseph S______<7MGT/M>(82) 12.929 @ 109.2 mphTimeslip
7.David Shepherd<7MGT/M>(84) 13.148 @ 112.2 mphTimeslip
8.Eric H___n2o+<1UZFE/M>(82) 13.190 @ 109.06 mphTimeslip
9.Helmsman____<7MGT/M>(85) 13.445 @ 112.0 mphTimeslip
10.Swank______<7MGT/M>(86) 13.649@105.93 mphTimeslip
11.Racefiend_____<7MGT/M>(8?) 13.886 @ 102.5 mphTimeslip
12.Pewee_Cressida<1UZFE/M>(8?) 13.926 @ 101.46 mphTimeslip
13.John Nguyen__<1JZGT/M>(86) 14.014 @ 110.0 mphTimeslip
14.Mailbyte______<7MGT/M>(84) 14.621 @ 100.0 mphTimeslip

 

[williamb82]

yeah tanya, but thats a ful gutted backhalved car running a solid rear axel wit ha 4 link. only makin maybe 300hp at most.

but heres a 5mgte that made some good power. though at 80 over it was 2900cc's

http://www.geocities.com/turbonos6/

 

[Tanya]

ah, I know, but there's still 2 other 12 valve heads on that list, and I'm sure there's quite a lot of decent HP 5M/6Ms that are undocumented (dyno and trackwise)

 

[mattjk]

Hey Aaron, my old friend Russ Matusevitch got into the 9's with his MKII supra.

The engine definately needs ALOT of headwork. Russ only put down 230whp with a the hks turbo kit. I think his last dyno was over 800whp.

 

[Tanya]

Hey Aaron, my old friend Russ Matusevitch got into the 9's with his MKII supra.

The engine definately needs ALOT of headwork. Russ only put down 230whp with a the hks turbo kit. I think his last dyno was over 800whp.

Yeah Russ was using a 6MGTE I believe, what ever happened to him, is he still racing??

 

[williamb82]

yes, russ was running a 6m, forged rods pistons, etc....

 

[mattjk]

Yeah Russ was using a 6MGTE I believe, what ever happened to him, is he still racing??

I just taked to him last month... he's busy running his bagel shop. :biglaugh:

No more supra... he's modding the viper and he still has the rwd, tubbed, ford 9", 1990 civic hatch that still doesn't have an engine.