F24 stroker upgrade 2010
03-21-2010, 05:28 AM
#1
Thread Starter
F24 stroker upgrade 2010
Last year I put together a F24C stoker that I used in a race meeting at the Australian Bathurst circuit.
My F24C powered race car is normally restricted to a stock engine/ecu in my normal racing category. This Bathurst meeting is unrestricted to I get to have a bit of fun.
I'll detail this build over the next few evenings when I get the time.
Last years build was detailed in this thread.
F24C last years build
This year I'm building up this motor with the following changes.
- High compression pistons
- E85 fuel
- Injection Dynamic 750cc injectors
- Toda Spec C cams and pulleys
- Supertech springs/retainers
- Toda ITB's
- Toda hyper single clutch and flywheel
First step was to clearance the rockers on the exhaust side to clear the primary lobes ( off vtec) of the camshafts
My F24C powered race car is normally restricted to a stock engine/ecu in my normal racing category. This Bathurst meeting is unrestricted to I get to have a bit of fun.
I'll detail this build over the next few evenings when I get the time.
Last years build was detailed in this thread.
F24C last years build
This year I'm building up this motor with the following changes.
- High compression pistons
- E85 fuel
- Injection Dynamic 750cc injectors
- Toda Spec C cams and pulleys
- Supertech springs/retainers
- Toda ITB's
- Toda hyper single clutch and flywheel
First step was to clearance the rockers on the exhaust side to clear the primary lobes ( off vtec) of the camshafts
03-21-2010, 05:41 AM
#2
Thread Starter
Toda suggests machining a retangular pocket in the rockers. I found this a major pain to do so I slipped some shim steel sheet between the roller and rocker body and took a curved recess over the complete rocker width. You only need to remove 0.5mm at the deepest part.
This years build increases compression from 11:1 to 13.2:1 by changing from -1cc to +10cc Mahle H22 pistons.
With the extra lift of the Toda Spec C camshafts I had to check if the valves would hit the pistons. Last year build with standard cams I knew the exhausts were < 0.080" from the pistons as the H22 valve cutouts are in the wrong place and the F20 valves pass over the flat piston top.
I measured the pistons movement vs degrees, then with no pistons/rods installed, dialed in the cams to 100 inlet 102 exhaust lobe centres, and measured the valve movement vs degrees.
My measurements said the valve were within 0.030 of the pistons, but they wouldnt touch.
I assembled #1 piston/rod without rings and using small springs in place of the valve springs, and locking the vtec pins in place turned the motor over and checked valve/piston clearance. I measured 0.040" which isnt really enough for high revs.
This years build increases compression from 11:1 to 13.2:1 by changing from -1cc to +10cc Mahle H22 pistons.
With the extra lift of the Toda Spec C camshafts I had to check if the valves would hit the pistons. Last year build with standard cams I knew the exhausts were < 0.080" from the pistons as the H22 valve cutouts are in the wrong place and the F20 valves pass over the flat piston top.
I measured the pistons movement vs degrees, then with no pistons/rods installed, dialed in the cams to 100 inlet 102 exhaust lobe centres, and measured the valve movement vs degrees.
My measurements said the valve were within 0.030 of the pistons, but they wouldnt touch.
I assembled #1 piston/rod without rings and using small springs in place of the valve springs, and locking the vtec pins in place turned the motor over and checked valve/piston clearance. I measured 0.040" which isnt really enough for high revs.
03-21-2010, 05:46 AM
#3
Thread Starter
I needed to cut some valve clearance flycuts in the pistons. Fortunately I have one of these in the workshop so out comes the pistons vice and a cutter.
I had a 1-1/4" cutter which at ~32mm was just right for a 31mm valve.
The cutouts don't look very deep but added another 0.070 extra clearance to the valves which was perfect. I didnt want to take more material than I needed off as this would reduce compression.
A quick check with plastercine confirmed plenty of clearance, especially radially.
I had a 1-1/4" cutter which at ~32mm was just right for a 31mm valve.
The cutouts don't look very deep but added another 0.070 extra clearance to the valves which was perfect. I didnt want to take more material than I needed off as this would reduce compression.
A quick check with plastercine confirmed plenty of clearance, especially radially.
03-21-2010, 05:54 AM
#4
Thread Starter
After deburring the pistons the bottom end could go together and onto the head.
Half installed.
Rest of the valves in and on goes the rocker assembly
The Toda throttle bodies were surprisingly well finished and port matched so needed almost no prep before fitting the injectors and onto the motor.
Tomorrow night I'm installing in the car, and hopefully off to the dyno on E85 by the end of the week.
Half installed.
Rest of the valves in and on goes the rocker assembly
The Toda throttle bodies were surprisingly well finished and port matched so needed almost no prep before fitting the injectors and onto the motor.
Tomorrow night I'm installing in the car, and hopefully off to the dyno on E85 by the end of the week.
