V2Rocket

Hi all,
I just got my used race-engine sleeved-block back from the machine shop after getting cleaned and bores measured.

Previously under the dirt, grime and oil I hadn't even noticed this before...there is some big welding work inside the lower balance shaft area. Looking closer there is a crack along most of that corner of the block going around onto the front face by the oil pump. I'm guessing someone had an off-track excursion and caught the lower BS bracket on something and tore the corner off.

This engine was running balance shafts when I got it. I only have limited history on it, but from what I know, it was built to compete in the old GT3 series in a car built by Kokeln. The blocked is sleeved to 4" bore to fit the 2.6L displacement limit. There was a knifed crank and Carillo rods in this motor attached to the 4" JE forged pistons. I don't have any idea what was done on the top end of the motor, I believe there was Vitesse stage 3 or higher turbo setup on it.

Before I got this engine it was running 360whp at 16.5 psi boost "so the legend goes." So the welding/fix must have been solid enough?

Anyways, to re-use this block I need to have the cylinders taken 0.020" over (there is a 0.005" taper to the bores and a noticeable ridge at the top of the ring travel) but I want to see if it's just a better idea to sleeve a fresh block?

Your comments are appreciated!

Tom M'Guinn

Blocks are so cheap, I wouldn't put much time, money or energy into a block like that. The seal area still appears cracked...

George D

Lart, please help a fellow Rennlister with a decent block for a few bucks? This one doesn't deserve any continued trauma, and will likely fail.

G

Voith

I would use it, looks to be welded well and it is non crytical area. crack in the mating area was not welded bc it would need to be machined. Just use flange loctite on the crack and put it together.

67King

+1.

V2Rocket

If I were to use it, could anything be done to "relieve" the crack at all, to remove jagged edges and prevent a stress spot?

The front balance shaft bearing is on its own housing so it shouldn't be affected. Again, this block has lived through some serious power over about 15 years so it's been run for some time with that repair on it...

xschop

I'd run it.... to the recyclers.

blade7

IF it's been welded properly with the correct filler wire it will be as strong as before it broke, though the weld looks untidy. I'd try and find a decent replacement block.

Van

It would probably be fine, but if I were dumping a ton of money into a race engine, I'd want it to be right...

V2Rocket

This engine's days of racing are over
Current intentions are to build a hybrid-stroker for a street car.

Van

If you're on a budget, and if you understand the potential of having to pull it out some day, I'd say reuse it.

Like you said, the biggest risk seems to be potential for oil leaks. Keep an eye on the oil pressure gauge in case the crack continues into the oil pump passage area.

If you really do end up making 400+ HP at the crank, something else is likely to give up the ghost first.

TonyG

If the bores are straight and round, the crank mains are straight, I'd race it.

It's been run like that for a long time without issues.

Obviously Vision didn't think it was a problem at the time either.

Run it.

TonyG

V2Rocket

i cleaned some more of the old loctite off the block and it looks like the weld was done from the balance shaft cover flange to the oil pickup passageway and then machined flat. not sure why they wouldn't have welded the visible crack if they were going to machine it though.

im going to take it back to the machine shop and have them check it out and see what they think.


The bores are tapered so the shop suggested 0.020" overbore to clean up.
My thinking is like yours as well, Kokeln/Vision is likely the ones who did this fix (unless they didn't build engines in year 2000 or so) and they thought it was OK to go. Landjet ran the **** out of this thing and it still was ok.

But either way, going to check it out.

azbanks

I've got a 951 block for sale. Includes balance shafts and covers. $300 +shipping

George D

Nice post.