LocostUSA.com

Pinion housings cast up beautifully in 4130, very happy with them. Still need a heat treat then machining.

On the topic of throttle bodies .
I've seen a very simple jig to machine the proper geometry in the butterfly .
The guy simply machined a nice round bar to the diameter of the throttle bore, and made an angled (let's say 5 degrees) face cut in the mill with two threaded holes, to attach the oversized bronze butterfly plate.
Then brought the thing to dimensions in the lathe, giving the plate the necessary out of round geometry .
For a cnc mill this is entirely a milling operation .

Thanks for the info Niko.


The donor car was taken for it's last drive today, as I need the axles from it for my daily driver. After a proper warmup captured a range of ballpark datapoints for setting up the speeduino on the test engine, wideband O2 will be used to refine the fueling table.



Sliced into the ignition signal wire to get a contact for the oscilloscope probe. Coil on plug dwell is 2.5ms at idle, around 3ms at higher loads.



The ECU grounds the injector coil so intercepted the wiring on the injector coil ground side to analyse the injector pulsewidth across a range of engine loads. Car in drive and brakes fully on, holding throttle at the desired MAP values that the speeduino will use as the engine load axis. Transmission oil got very hot but as it's off the road now not an issue.



DPscope capture of full throttle injector pulsewidth - leads are set to 1:10 so voltage captured properly, however not sure they were correctly attenuated, but was really only interested in the pulsewidth anyway.



The laptop is running the DPscope software, works good enough for my budget/purposes. 16 british pounds plus shipping.
https://www.picaxestore.com/catalogsear ... q=+dpscope

3D printed a housing and soldered leads to the 2 BNC connectors.

The original position does not suit the Mercedes SLK door latches being used for this build, however with a bit of "adapting" (using a grinder to remove the superfluous material from the OEM parts) and swapping around the installation can achieve something functionally very close.


The component on the left is a standard right hand door assembly, where the mechanism would be mounted inside the door. Dihedral doors typically have the latch mechanism in the body and the striker pin on the door, so in this case taking a cutdown LH mechanism (shown on the right) and rotating it so the striker approaches from the topside works - at least in the CAD assembly.


Countless hours have been spent trying to resolve the clearance around and mounting of the modified door latches to the frame, happy now with the solution that ties the passenger seat belt retractor mount into the door latch mounting plate and a major chassis node.

Next casting off the rank is a test bellhousing - hopefully for use on the secondary motor as no bosses or cutouts for the starter were detailed as I have run out of 2023. Will be cast in aluminium grade A356.

Those are impressive - 3D printed, I take it? Did you do any hand finishing work on them or did they come out that smooth from the initial printing?

What kind of casting facility do you have? Those are big parts. I have daydreamed about making small cast parts such as the windshield stanchions and similar things, but have not followed through due the complexity of setting up all the casting components needed. Your setup must be substantial. That larger piece will require a lot of metal.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Awesome progress mate!

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Scratch built turbo V8 hot-rod in progress
http://locostusa.com/forums/viewtopic.php?f=18&t=19549

How much shrinkage did you include in the pattern? I think it is roughly a 1/4 inch in 20 inches. Did you consider lost foam?

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Lonnie, they are PLA prints given a light sanding only - it burns out of the shell nicely giving a decent investment casting all going well. I have access to 2 x 250 kg and 2 x 500kg induction furnaces, but very rarely cast more than 80kg in one shell/part.

Thanks Beezle!

Mv8, general guide I use is 1.3% for aluminium, 1.8% for steel and 2% for stainless steel. However this is highly geometry dependent and the way the ceramic mold can hold up the shrinkage of the part dimensions while contraction occurs during solidification and cooling can be quite surprising. The advent of 3D printing has allowed us to cast the part first, measure the shrinkage factors on critical features and then make the production tooling using these lessons. I do use lost foam but the pattern making is usually very time consuming and harder to make as dimensionally accurate as the prints.

Good example is this small press tool I 3D printed then cast in 4140. It easily bends the intake tubes for the airboxes.


The tool serves as cutting guide for the ends


1 dozen inlets took an hour to make with a bit of learning involved.



I will need to turn up some bellmouths and weld them to these tubes, then weld the tubes to the CNC'd lower plate which then bolts onto the standard honda lower intake manifold

This is going to be sooo cool.

Do you have a good recipe for castable refractory? "Fire clay" has been difficult to find here with a big push toward high alumina mixes as a replacement for natural clays. Some ingredients I'm looking at are silica sand, crushing perlite, portland cement, lime, a natural clay that is available such as kaoline, bentonite, or high iron red, and gypsum.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I'm with @seven13bt - this is going to be so cool.

By the way, which CAD program(s) do you use? Just curious.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Thanks Guys, progress is addictive!

All modelling is done on Solidworks.

If stateside would recommend shell materials from https://buntrockindustries.com/materials/

Bellhousing casting came out well for the first attempt;



Fit looks good so will proceed to heat treat and machining in the new year - there was generous machining allowance included at each end.




Also knocked off a small task of blocking off the auxiliary line in the corvette fuel pump with a small brass pin - now it needs a tank to be fitted into!

Very nice. Very impressive.

Also, Merry Christmas to you.

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Looks great.
Thanks for the link.
I'm making the kiln right now. For shell over foam, dish soap and water sprayed and dryed on the foam is effective at getting a thin, permeable drywall dip to adhere and provide a good finish.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12