Seven Bolts aren't bad...are they. (rebuilding one)

[caspers_dsm]

It recent aquisition of my new DSM, i received a seven bolt shortblock.

In my recent hours of searching on my new toy and the infamous "crankwalk", i have found the block and crank aren't the problem, its the assembly (clearances in the bearings). That being said, there should be no reason why using a seven bolt for a rebuild, if done with tight clearances, would be bad. I am not knew to engine assembly and i know any "sloppy" crank assembly is trouble.

I would also like to confirm..... a rebuilt shortblock using 1st gen "big rods" and forged pistons with removed B.S., will handle mid 300 maybe even 400whp.

Thanks guys. I hope to get this thing underway.

 

[DJYoshaBYD]

just do some research on crankwalk and you will see what everyone is talking about... from what I understand, the thrust bearings go out because they did a shi++y job making the crank..

I still dont understand why DSM would change from the 6bolt to the 7bolt in the first place... it.. confounds me..

 

[caspers_dsm]

just do some research on crankwalk and you will see what everyone is talking about... from what I understand, the thrust bearings go out because they did a shi++y job making the crank..

I still dont understand why DSM would change from the 6bolt to the 7bolt in the first place... it.. confounds me..

I have read a great deal on crankwalk, which is why i asked....from what i read it has nothing to do with the crank itself, but the bearing clearances, is this correct?

 

[numlock666]

there are many "theorys" on why crankwalk happens to 7bolts, but all in all, there is no definite answer and no one really knows. Why would you want to build a 7bolt for anyways? Theres an abundance of 6bolt blocks at any wrecking yard, no crankwalk, stronger internals, lower compression, bigger head studs, bigger intake ports and the list goes on. If you have the skills and patience to maticiously check and recheck all tolerences when putting an engine together properly you can easily do a 6bolt swap. I can teach a Honda kid to do a 6bolt swap. What im getting at is why would you want a 7bolt in any case?

 

[Bmxr152]

Yeah i know, build a 6 bolt, or even get a 6 bolt block and replace it with stock stuff and it should be stornger than a stock 7 bolt anyways.

 

[turbo90gsx]

A stock 6 bolt will hold 400hp easily, why build up a 7 bolt just to hold as much power?

 

[talon187]

get a 6bolt youll be happy in the end i had a 2g gst and it got crankwalk and it got so bad the turbo got runined from small metal shaving going threw the motor

 

[caspers_dsm]

Well, because i have the seven bolt sitting here..? Thats makes it pretty convenient
I didn't realize there were THAT many differences to the two motors. This site has lots of great info, its just hard to find it all sometimes.

I haven't seen many 1st gen's at the bone-yards here, granted i am usually looking for yota/suzuki parts.

On another note (no i haven't searched for this yet, be gentle) is there a way to identify whats in my TSi, the PO really knew nothing more than it was turbo.(He bought it with some mods that were parted)

 

[TrboANTsi]

from what ive read its the crank on 7 bolts. its not as dense as teh 6 bolt. i have a built 7 bolt which i just got installed. and i had the crank nitrited. yes i could have done a 6 bolt. but i like trying different things.

 

[numlock666]

6bolts stopped making homes in dsm in early '92. So if you have a 95, sorry friend but 99% chance its a 7 unless someone already swapped one it but you would easily tell. the 6bolt has its perks, Lower compression = more safety margin and room for high boost. OIl squirters. stronger rods, thicker head studs, external oil coolers, higher lift cams, bigger ports, crankwalk is unheard of, ignition timing advancement and many more things. Only thing I would save from your 7bolt is the exhaust manifold and o2housing.

 

[caspers_dsm]

My manifold is cracked and i ordered an evo III, it didn't have an 02 housing, so again...i ordered the evo III.

Going by the way this engine bay looks, i wouldn't be surprised if someone had swapped it out before.


How could i identify which motor this is?

 

[VETTE_50_TH]

Here is a thread talking about it.

Here is Vfaq talking about the differences.

James

 

[DSM36]

well there a few different ways to tell, does it have a round cam and crank angle sensor on the top left passengers side of the valve cover? or is it just a rubber plug from the valve cover gasket like 7 bolts have, the head should have a date in the front drivers side, 90-92 1/2 =6 bolt, intake manifolds are different but a 6 bolt manifold is a common upgrade for the restrictive 7 bolt intake manfold so that may not be a good way to tell, you could also check the spark plug wires and see if there swapped, or check the injector wires to see if they have been changed also

 

[c4uldr0n]

Not all 7bolts are created equal, my 1G 7bolt is holding up just fine with 130k miles on it! Daily driven w/ a 50trim and ~20psi

 

[caspers_dsm]

Here is a thread talking about it.

Here is Vfaq talking about the differences.

James

*EDIT* Guess i should have read the second thread..DOH!! Thanks James!!

My head is a seven bolt, as it has the larger studs for the ex. manifold.*EDIT*
Well, no such luck on the block, its a 7 bolt as well. The oil pan is def. from a late model.

I really wish i had the history of the car.

 

[caspers_dsm]

Not all 7bolts are created equal, my 1G 7bolt is holding up just fine with 130k miles on it! Daily driven w/ a 50trim and ~20psi

I figure i will source the EVO III mani, turbo, o2 housing. I need to get an intake tube and mas. I need to weld up an exhaust once my pipe gets here...then drive it and see what it does.

I'll be boneyard hunting today for the hard coolant line to the turbo

 

[CanadianTSi]

I would also like to confirm..... a rebuilt shortblock using 1st gen "big rods" and forged pistons with removed B.S., will handle mid 300 maybe even 400whp.

A Stock 7bolt will.

 

[caspers_dsm]

Good thing i asked, i went and bought a battery today, motor will turn over, timing belt rotates, i have no compression on any cylinders.

So now what's that about a six bolt, and where is the best place to find one....