Rebuilding a Race Engine

[roaldin]

Too many years ago to think about I ran a short stroke 1920cc engine that included unconventional (for the time) high gudgeon pistons and long rods, it was a much nicer/faster engine IMO than equivalent 1952cc long stroke engines I had used (under 2 litre class). I don't remember details now but from memory stroke comparison was 78mm vs 86mm.
Too long ago to have any paperwork from those setups now... As for remembering rod ratios, no chance...
I think bore was 88.5mm vs 85mm but could be wrong. The bigger bore allowed for better airflow around the valves so maybe not so relevant to the scenarios above if bores are equal, but anyway, 2c worth.

I am interested in this discussion as my GT runs an alloy 364 and after only 3500km the engine is "enjoying" a complete rebuild - all new rotating/reciprocating assembly, liners too...
Not happy!

Tim.

 

[Jim Nielsen]

Ross,
Some other things to consider is your current trans ratios. Drastically altering the power output and power curve can change the optimum gearing. Also do you run slicks? If so I am guessing you are not traction limited on acceleration. If so I can highly recommend a light weight engine assembly. Makes engine responce quick and very nice to drive. I went to a multi plate clutch and was able to drop alot of weight from the flywheel. It made a big difference. I dont know what your spending limit is but you considered an alloy block? It may not add HP but it will help every where on the track.
Last you know your car and should taylor the new engine to the cars needs. IE you are already able to overpower the tires off the corners. Adding bottom end may not be the best thing. Go more for top end where you can put it to use on the straights. Now if most of the circuits are tight then a torque engine can be better.
Do you run a roller cam?

Jim

 

[Ross Nicol]

Looks like I've opened up a can of worms here. My experience with engine internals is not as developed as most of you learned gents but I can offer feedback from my exploits in the driver's seat. This engine I'm rebuilding was a 302 and I rev limited it to about 6700. It had good enough breathing and power to get up to 6500 in 5th/top gear by the end of the straight at Phillip Island. I found it couldn't break traction in 2nd gear coming out of a slow corner so I conclude a torque increase will be good for the gearing I have. I only use 1st gear for race starts and it gets me going nicely. I've found recently that with the improvements in suspension I can maintain a higher corner speed for 2nd gear corners however any increase in torque will be welcomed for coming out of these corners. Russ has mentioned this engine is likely to be refreshed once a year and this is likely. Jim I do run slicks, I have an alloy fly wheel but sometimes I find the revs drop off too quickly and I'm having to blip the throttle again, (usually after Ross has fluffed a gear change). Does spin up fast though. As for Alloy block well I have this one and my fiscal controller ( Cheryl ) is already asking those awkward questions like ( do you really need it?). I have a weight reduction program in place at the moment, I have ordered light weight clips from RF and hopefully their fittment will coincide with my next race meeting.
Tell you one thing, I learn a lot from discussions like this, alot of it you don't read in books.

Ross:thumbsup:

 

[Ross Nicol]

Took the block,crank,rods,pistons and camshaft to Aviation Component Services at Moorabbin airport yesterday for crack testing. I know the owner as he is a fellow racer. I purchased a large plastic tool kit to transport the block in and a metal one for the crank. As you can imagine these are large cases and I had forgotten until I exited the 'Supercheap Auto' check out, with them, that I was in the Lotus Europa:laugh:. Took me quite while to get the cases into the passenger seat and to leave enough room for the driver:tiny:. Think of the room in a GT40 and then halve it for the Europa. Lucky I didn't have far to travel back to the factory. Should get the bits back on friday.

Ross:thumbsup:

 

[Maurice Butler]

Have you considered belt drive for the cam rather than chain?

They claim better timing accuracy and saving of horse power. Would love to see the comparison on a dyno.

Typical set up here Jesel Belt Drive Kit - JEGS for the lurkers:lurker: that haven't seen one.

Looking forward to seeing your low flying rocket on the track again, may be as Low Down Racing? :evilgrin:

 

[Ross Nicol]

I'll stick with the chain thanks Maurice less chance of valves meeting pistons.

Ross:thumbsup:

 

[Ross Nicol]

Got the parts back from crack testing yesterday-

Pistons - all ok
crank - all ok
Rods - all ok
Cam - all ok
Block - NOT OK!!!!!!!!

2 cracks found in the webs on one side of #2 main and #4 main. These cracks follow the stud thread down on both sides. Photos show both sides. Cracks are inside the red highlight pen lines. Damn I guess I'm now going to have to purchase a new block.

Ross:thumbsdown:

 

[Garry]

Ross, That's a tough break, but better to know it now than later-less exspensive in the long run. Not to mention the frustration and down time of the races you would miss.
Garry

 

[Ron Earp]

Block is cheap. Since you don't have block rules I'd get some serious hardware in there. Glad you did the checking.

 

[flatchat(Chris)]

10 outa 10 for doing all those checks Ross --- we're getting a bit tired of Ford shrapnel all over our race tracks.:laugh:

 

[Randy V]

:thumbsup::thumbsup::thumbsup: for doing all the checks....

Chin up friend... Think of all the anguish you've saved yourself down the road. Forfeited entry fees, all the expense of towing/lodging - not to mention the inherent dangers that we all face when we lose an engine at speed....

 

[Neal]

Time for that alloy block... epper:

 

[Scott Calabro]

A GOOD PRICE!

8.2 deck x 4.125 bore Dart $3,819 or about 4,752 AUD ...

Flatlander Racing - High Performance Engine and Racing Parts

 

[Ian Anderson]

Or the whole hog and go for a Cleavor!

ian

 

[Jac Mac]

A GOOD PRICE!

8.2 deck x 4.125 bore Dart $3,819 or about 4,752 AUD ...

Flatlander Racing - High Performance Engine and Racing Parts

He could get the block, rods & half a piston set for that in NZ if he moved his butt right now!

 

[Ross Nicol]

I have a new Block. Dart Sportsman. Hope this one doesn't have any cracks in it. Of course it is soon to go off for testing.
Weighs more than my other 2 blocks. Very beefy around the webs.

Ross:thumbsup:

 

[Garry]

Good one Ross. From what I have heard, the Dart blocks are great, however I will look for comments from more knowledgeable members on this forum.
Garry

 

[Randy V]

Good job Ross!

Improved oiling -
Far stronger -
1/2" headbolts/studs as I recall ((good))

Doggone thing is beautiful eh?

 

[tim]

Hi Ross, what sort have money has the engine set up cost you if its not to rude to ask?

thanks Thomo

 

[Ross Nicol]

It's been a case of me taking 1 step forward and 2 steps back. I am starting the build again with a new Dart block owing to the discovery of 2 cracks found in the block I was proposing to use. It's probably a good idea to describe the specs of, and how I sourced this engine, how I damaged it and the planned rebuild.
As purchased
-------------
302 Block- Ford Racing B50 Mains 2,3,4 converted to 4 bolt
Crankshaft,rods,piston-Crower steel crank and rods, JE pistons
Heads- Edelbrock Vic jr
Run with dry sump oiling system
Engine was built in the US and was used to power a Daytona Cobra replica in Australia prior to my purchase.

I fitted this engine to my RF40 which proved to be quite a lot more powerful than my original powerplant. The suspension and handling needed work at that time and I was unable to make the most of the increased power. It was at this time I took my eye off the ball regarding engine maintanence and the engine starved for oil during a race. After strip down I found the Crank and 2 rods badly damaged. Piston to bore clearance was found to be too high as well.

Now onto the rebuild
--------------------
I decided to fit a 347 Scat stroker kit and purchased the kit comprising new crank,rods and 4.030 pistons. The block was bored, mains line honed and bore bottoms knotched for clearance. The crank was fitted with heavy metal for internal balance. I fitted the crank to the block but found the piston tops cleared the deck by .015 so piston tops were trimmed for zero deck. It was at this point that I was advised to have parts crack tested and the cracks in the block were discovered.

Results
-------
So now a new Dart block has been purchased my engine rebuild is becoming more a new engine build, due to the new block, crank , rods and pistons certainly most components making up the short motor. Of course any money spent on the B50 block preparation (my former block) has been wasted. I have indeed learnt from this experience though and mistakes like this will not be repeated.

Ross:thumbsup: