Rebuilding a Race Engine

[Ross Nicol]

Ok bit of a catchy title I know, but I thought I would start this new thread to detail the rebuild of my race engine. I'm hoping for help and construction hints along the way, so maybe this thread can become a guide for others who choose to build their own engine. This system worked so well when I needed help with the suspension on my car, I thought a similar approach where I do the work and you guys help with your knowledge, would be just the ticket:idea: . I have a lot of paper work from the original build as a 302 and I'll put up a dyno sheet to test if this scan is readable as a jpeg.
I have retained the original B50 block but the Machine shop has supplied and prepared a Scat 347 stroker crank and rods. More details to come.

Ross:thumbsup:

 

[Ross Nicol]

A pdf may be better I think

 

[Ross Nicol]

I'd like opinions on these flow figures for the Victor Junior heads

Ross:thumbsup:

 

[Iain]

Ross,

Are you heading for torque or hp ?

Iain

 

[Jac Mac]

Ross,

Are you heading for torque or hp ?

Iain

twork n twubble!

 

[Ross Nicol]

You might have pre-empted my thoughts Iain. I would like to have 500 to 550hp but the dyno sheet shows only 438hp at 6800rpm. I was told the Motec dyno is conservative and this could be the reason for the low hp result. This is the reason I'm suspicious of the heads and their ability to flow, but the intake flow from the charts indicate support for 597hp at .6 valve lift. I think Jac Mac is preparing to serve something on me, that may not be good:uneasy:. I anticipate there will be a torque increase due to the extra cubes.
Ross

 

[Ross Nicol]

Ok to give some background on this engine-
I purchased it in 2005 from Richard Bendell (CEO of Motec) who had been running it in his Cobra Daytona (replica) prior to switching to LS Chev power.
An engine builder in the US called R.P.M had built it, and apparently it had a lot of money thrown at it.
I fitted it to my RF40 but changed the 4 barrel Motec induction to my DC&O 8 stack (this may not have been a good Idea) but I didn't have the opportunity to do back to back Dyno tests. The New Roaring forties helped me by funding the tuning on their Dyno.
The car had a lot more power and I was able to move up the grid due to this, but was hampered by the cars poor handling at this time. Actually it was the handling issues that partly bought this engine undone. Well apart from my stupidity that is.
After major suspension changes to the car I arrived at Phillip Island race track for a meeting only to find I had major oil surge in the corners.Well wanting to stay out to test my new suspension and thinking I would get away with it I carried on until the bearings cried 'no more'.
Luckily I hadn't thrown a rod but the Crower crank and 2 rods were badly damaged. So from that time until now I have been using the original (fairly stock) motor in the 40 until 2 weekends ago when it cried (no more!) and went bang. This situation now requires an accelerated rebuild of the RPM engine and here we are. A lot of work has been done, particularly by the machine shop (which I will discuss) but I am still at the start of the build.
I'm hoping to share the experience and learn from it as well.
Russ Noble has set the ball rolling with his advice to have the brand new crank crack tested before installation. I presume I should have the rods done as well. I wouldn't have thought of doing this as I would have assumed new to be 100% tested but my first lesson has been when building a high RPM race engine check and measure everything.
Photos to come.

Ross:thumbsup:

 

[Russ Noble]

Russ Noble has set the ball rolling with his advice to have the brand new crank crack tested before installation. I presume I should have the rods done as well. I wouldn't have thought of doing this as I would have assumed new to be 100% tested but my first lesson has been when building a high RPM race engine check and measure everything.
Photos to come.

Ross:thumbsup:

In my PM I said "rotating assembly" ie crank, rods AND pistons! Also, ASSume nothing!

 

[Ross Nicol]

In my PM I said "rotating assembly" ie crank, rods AND pistons! Also, ASSume nothing!

Ok Boss:embarassed:

 

[Trevor Booth]

Rotating pistons !! well I never -)

 

[Russ Noble]

Now, now Trevor. Stop being a Wankel! :lipsrsealed:

 

[Trevor Booth]

good one Russ

 

[Maurice Butler]

Have you thought how you are going to balance the rotating assembly (pistons included) to be internal or external, if external 28oz or 50oz. oh the cam rotates don't forget that either, vibration is energy being used the wrong way, so may internal would be best if possible

 

[Ross Nicol]

Ok I have some pics. I spent the afternoon down at the factory cleaning up my engine room to make way for the rebuild. The first pic shows the crank in the block, 2nd one shows the crank removed to go off for crack testing and the third shows the main bearings back in and waiting to be torqued for clearance checks. Maurice if you look closely at the pic of the crank you'll see it has heavy metal in the counter weights. I had the machine shop (Saliba engine reconditioning) balance the crank so it is internally balanced. They supplied the pistons,crank and rods after machining the block so I assume (no not that word again) they have weight matched the pistons and rods and also used those weights to balance the crank as a unit. I will check with them as my orders are not to assume anything.:uneasy:. I was going to remove the camshaft to check the bearing oil holes are lined up ok. They were fitted by Saliba. So if I have it out should I crack test it too? I've never heard of camshafts being balanced but what do my bosses think?
Ross:thumbsup:

 

[Jac Mac]

Normally one would crack test before balancing etc, purely for fiscal reasons. Since this is apparently a rebuild of the ex daytona block that suffered an internal failure I hope you also magnafluxed the main bearing webs & cyls in the vicinity of the problem. One other thing, the clearance cutouts at bottom of cyl bores appear very large, with your 3.4" stroke this might be detrimental to piston stability at BDC, a problem with all SBF motors and in this case with the longer stroke even more so. One of several reasons why I encouraged you to limit stroke to 3.25", however its apparent that you have been swayed by the Noble theory of bigger is better!!

 

[Ross Nicol]

Oops look out it's my big boss, now where can I hide? Jac I suppose I'm lucky in some ways but unlucky in others. I have to admit I was about to rebuild this motor without any crack tests or clearance checks and I expect to be wrapped over the knuckles for these omissions. I realize now why the build sheet for this engine was so detailed and I understand a lot more about the detail it contains.So for Fiscal reasons Ross will crack test before balancing in the future. I hope I can talk my way out of your next point regarding the previous internal failure of this engine. The engine was still running albeit with a tapping knock. When the bearings failed I slowed down to crawl back to the pits. I don't believe parts other than the crank and rods in the failure area were stressed although I will maganaflux the block to be sure. I'll take up your point about the large cutouts with Saliba, they do a lot of this sort of work and have a good reputation so I will give them a chance to explain. I have been swayed by a few Noble theories but he didn't play a part on my decision to stroke to 347. There was a fiscal consideration due to this conversion being so common in OZ.

Cheers Mate
Ross:thumbsup:

 

[colin artus]

More spec needed! Cam, cr, rod length, fuel etc. Given that you are increasing cc by some 15% it's not unreasonable to suppose that 500 bhp is attainable.

 

[Jac Mac]

The engine was still running albeit with a tapping knock. When the bearings failed................I slowed down to crawl back to the pits............... I don't believe parts other than the crank and rods in the failure area were stressed although I will maganaflux the block to be sure.
Cheers Mate
Ross:thumbsup:

In future & with an obvious seizure or oil supply issue.....Switch off ... STOP and suffer the indignity of being towed back......In those brief seconds while the bearings & rods are trying to weld themselves to the crank journals the thrust loads applied to cyl walls & the twisting moment applied to the crank etc are enormous. It might not actually crack a cyl wall, but can distort it out of round . IF your operator was aware of the blocks recent history at the time he bored the block a precheck for any abnormal bore measurements plus an audible change when boring/honing those cylinders would be a warning of a problem.

 

[Pete McCluskey.]

Ross are you talking rear wheel H.P. or flywheel?

 

[BruceA]

Ross, what sort of oiling system were you using - did you have a dry sump or wet? Just being curious because you mentioned 'oil surge'.