7M parts in 5M block (one crazy idea)

[Mr. Y]

Hi guys.
At first sorry for small offtopic about 5M here but please listen to whole my story and you'll probably understand...

I own pretty modded '87 5spd (400+whp i think) but more I mod it becomes less daily-driver friendly... And one more thing really annoy me - with all that power I haven't any success at 1/4 mile...
So there are two ways: make my MK3 race-only car and buy Lada daily driver or... tada! Buy MK2, make it racecar and return MK3 in (nearly) stock form to enjoy it.

Let's see what do I have:
- internally stock 7M (to be built)
- pt67dbb, FFIM, exhaust
- AEM and all fuel components
- 7M pistons (probes) and rods (eagles)
- built 7M head
- TH350 setup on the way (must be in my garage within a month)

Now the questions (if you know some answers or just have an opinion - feel free to post):
- how much stripped MK2 rolling chassis lighter than stripped MK3 targa?
- will that combo work: 5M engine block, 5M crank, 7M rods, 7M pistons, 7M head?
- will 5M block handle enough power (let's say 700whp)?
- is 5M oil pump adequate?

Ok, I already see question "why not just swap built 7M into MK2" and here's answer: stupid laws... to make that swap legal it will cost more than good bb-turbo (thanks to corruption).

thanks in advance for answers and opinions

 

[Doward]

You can't put a 7M block in there and just tell them it's a 5M? I can't see they'd see any difference in the block...

 

[4U2QUIK]

yeah no kiddin, just have a sticker that says 5mgte and put it where the 7mgte sticker goes. Most people including smog shops seem to think supras are 4cyl. cars anyway. I even had one of the dmv people try to put my car down as a 2.5l 4cylinder when I was registering it.

 

[benchwarmer]

You should do a search over on CelicaSupra.com, they will have more information on this. As I recall, and I am notoriously inaccurate, you can put 7M internals into a 5M block to achieve a 6M engine. I might have that backwards but a search on CS will yield an answer.

 

[85celicasupra]

Now the questions (if you know some answers or just have an opinion - feel free to post):
- how much stripped MK2 rolling chassis lighter than stripped MK3 targa?
- will that combo work: 5M engine block, 5M crank, 7M rods, 7M pistons, 7M head?
- will 5M block handle enough power (let's say 700whp)?
- is 5M oil pump adequate?

Ok, I already see question "why not just swap built 7M into MK2" and here's answer: stupid laws... to make that swap legal it will cost more than good bb-turbo (thanks to corruption).

thanks in advance for answers and opinions

The Mk2 will be lighter...stock for stock the mk2 is much lighter so I can only imagine a stripped one being much lighter.
The 5m block and 7m blocks are almost identical, there are a couple different water jackets and such, couple other small ones.

I see no reason why the 5m block and crank couldnt handle the power, you have everything else upgraded you should be fine.
I would suggest upgrading the 5m oil pump. They make a upgrade/higher volume pump.

you may run into issues with belts lining up because of the different locations of the alternator and other belts because using the 5m crank means you have to use the 5m pulley.

It is definitely worth your time to get on Celicasupra.com and make massive use of the search button and pick the brains of some of the experts.

 

[85celicasupra]

also as for doing just a whole 7m swap that is a better idea. I dont know where you are located but on cs.com there quite a few members who have done 7m swaps and are legal in the smog nazi state of cali. The blocks bolt up, the only thing you have to deal with is a wiring harness and computer, which you have to deal with anyways when swapping the head over.

 

[Mr. Y]

Thank you for replies guys.

I can't just put 7M because our inspection ckecks number stamped on the block (see my location).
So if I take my 7M out MK3 and put it into MK2, I'll have a lot of headache (paperwork with 2 swaps... too much money for bribes and time)

 

[tekdeus]

Mk2's are light, but 400+hp will likely break the weaker transmission and rear differential. Plus it fits smaller wheels of an odd-ball 4-bolt pattern.

 

[hvyman]

how often do you have to do inspection?

 

[Mr. Y]

to hvyman: actually I can be stopped at any time by policeman... They call it documents checking... But if documents are ok, they begin to find something that isn't ok (to make some money)... And if my engine number won't mach documents, they'll assume I've stolen car and they take it. When you come to take it back you can miss some parts like battery, radio and so on... ask me how i know :-(

 

[RazoE]

Would a 7M head bolt up to your 5M block? a twin cam 2.8L *M sounds like fun..

 

[OkieRA29]

Gotta remember what my mechanic told me. I bought my 1977 RA29 from him. I believe that the head from the 7M will fit on the 5M block. This helps three ways, it will let you keep your legal block, ups your displacement to a true 3 liters and gives you the better cams and heads. I think also that you can interchange the 5,6 and 7M cranks as well. The best place to discuss this would be over at celicasupra.com. Those are the Mk2 supra guys and would be most knowledgeable about this kind of stuff.

 

[Tanya]

Now the questions (if you know some answers or just have an opinion - feel free to post):
- how much stripped MK2 rolling chassis lighter than stripped MK3 targa?
- will that combo work: 5M engine block, 5M crank, 7M rods, 7M pistons, 7M head?
- will 5M block handle enough power (let's say 700whp)?
- is 5M oil pump adequate?

Ok, I already see question "why not just swap built 7M into MK2" and here's answer: stupid laws... to make that swap legal it will cost more than good bb-turbo (thanks to corruption).

thanks in advance for answers and opinions

My 1985 Supra weighs 2,813lbs with no gas and no driver, it was 3,060lbs when I started. So yes, very much lighter than a MK3 targa. My car would definitely be in the low 2,700lb range with a carbon fiber hood and the rear seats removed.

You cannot use a 5M crank with 7M rods, I am pretty sure they will interfere with the bottom of the cylinders or something like that. The crank has to be matched to the rods, 5M for 5M, 7M for 7M, etc. The blocks themselves are interchangeable. The later model 5M blocks, 6M blocks to early model 7M blocks are all almost the exact same casting besides a few discrepancies (such as turbo drain, dipstick tube hole, etc etc)

You can use the 5M block, swap the 7M crankshaft, rods and pistons into it and use the 7M head if all you need is the 5M casting mark to make it "legal"

As for handling the hp, I don't see why not, as long as it has a good tune. Of course, any engine will be explosive on a bad tune. Russ Matusevich was running upwards of 700+whp in his 6MGTE mk2, and since the blocks are nearly identicle, there you go.

 

[dulobast25]

Gotta remember what my mechanic told me. I bought my 1977 RA29 from him. I believe that the head from the 7M will fit on the 5M block. This helps three ways, it will let you keep your legal block, ups your displacement to a true 3 liters and gives you the better cams and heads. I think also that you can interchange the 5,6 and 7M cranks as well. The best place to discuss this would be over at celicasupra.com. Those are the Mk2 supra guys and would be most knowledgeable about this kind of stuff.

maybe i dont follow..how does bolting up a 7m head to a 5m block up your displacment?
be careful on the idea of exchanginmg cranks etc. the rods themselves MAY be intechangable, but got to TOYSPORT, CA website. According to them, you can swap heads but you cannot swap heads between 5 and 7m. You can swap cranks between 2m-5m and between 6m and early 7m. late 7m the crank is counterweighed different, but you still can swap it. the cranks changed between 5m and 6m and the the timign covers and oil seals may not fit proprely. Do a bit more research on that one. there would be some serious machining to do. do they even check the head? if not swap heads but all the timing covers AND piston s would have to go with the head. the bore is the same so that should be the issue, jsut the piston to rod pin fittment. I would get the 5m head ported as it is a more stout head with flatter power band and change to a 7m oil pump run a crank scraper get the enginebalanced and blueprinted, run a metal headgasket to lower the conmpression and boost the snot out of it. Run the 7m turbo electronics. Tap the block for a 2nd knock sensor. The cps issue can be handled.. ask me how.

 

[Tanya]

maybe i dont follow..how does bolting up a 7m head to a 5m block up your displacment?
be careful on the idea of exchanginmg cranks etc. the rods themselves MAY be intechangable, but got to TOYSPORT, CA website. According to them, you can swap heads but you cannot swap heads between 5 and 7m. You can swap cranks between 2m-5m and between 6m and early 7m. late 7m the crank is counterweighed different, but you still can swap it. the cranks changed between 5m and 6m and the the timign covers and oil seals may not fit proprely. Do a bit more research on that one. there would be some serious machining to do. do they even check the head? if not swap heads but all the timing covers AND piston s would have to go with the head. the bore is the same so that should be the issue, jsut the piston to rod pin fittment. I would get the 5m head ported as it is a more stout head with flatter power band and change to a 7m oil pump run a crank scraper get the enginebalanced and blueprinted, run a metal headgasket to lower the conmpression and boost the snot out of it. Run the 7m turbo electronics. Tap the block for a 2nd knock sensor. The cps issue can be handled.. ask me how.

Slapping a 7M head on a 5M block does not up the displacement, obvioiusly. but again, the heads are interchangeable, as long as the pistons are from that associated block for the valve reliefs (7M head needs 7M pistons, and vice versa)


Serious machining to do? Where?

For swapping a 7M crank into a 5M block, you would also need the 7M rods, 7M oil pump drive shaft, 7M lower rear timing cover, 7M front main seal and 7M crank pulley.


I wouldn't bother trying to keep the 5M head if you already have a 7M head built for it. The wiring to a mk2 wil be an obscene headache, but can be and has been done numerous times.

 

[bigaaron]

5m and 7m cranks are different, different snouts for different pulleys.
[/end thread] :biglaugh:

You'll find some good info here ----> http://www.supramania.com/forums/showthread.php?t=33823&highlight=5m+crank+7m

 

[Mr. Y]

Ok thanks everyone for great information... Looks like that 5M build isn't simple as it appeared before... I'll think twice once again. Better have good running MK3 (yes, heavier and slower) than get two supras without engines and no money left...

/thread

 

[Tanya]

5m and 7m cranks are different, different snouts for different pulleys.
[/end thread] :biglaugh:

You'll find some good info here ----> http://www.supramania.com/forums/showthread.php?t=33823&highlight=5m+crank+7m

^duh, silly. I thought that was kinda obvious.........I think I covered the basics already sir




....as for the 5M build being simple... I don't see why it is not...

you take your 7M stuff and slap it in a 5M block... if you have built an engine before, it's pretty much common sense stuff..... the only difficult part is wiring for a 7M to a mk2 Supra...

 

[Poodles]

As once mentioned in another thread...modeling clay on the casting number...

Though I think they'd notice the 7M head...

 

[OkieRA29]

Sorry, I defer to the older guys, I was thinking 6M and 7M cranks, which can be interchanged, right? I don't know, too much work and not enough sleep right now. It is my friday though, got all of Thanksgiving holiday off. Well, not really, I have to come in and fly in the chopper for the black friday morning stuff:nono: Headed home right now to start kicking back with a cold shiner and dreams of running supras:biglaugh: