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GT750 Powered Race Car (D-Sports Racer)

Started by sav0r, July 22, 2019, 06:22:45 PM

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sav0r

I printed the new impeller and cover and some where along the line I messed up the dimensions on the cover. We tried a test fit, and I could already tell it wasn't going to fit, and sure enough it didn't fit. Back to the CAD software. Better test fit with plastic than make chips though. The last time around I machined the wax test part, the 3d printer is easier, albeit way slower.

www.chrislivengood.net - for my projects and musings.

sav0r

I got the dimensions on this all ironed out. We test fitted a new print of the impeller and cover. All is good.

I went ahead and did some final design on the cover. I just wanted to make it less of a slab and pretty it up some. I'm not sure I achieved that, but it at a minimum is no longer just a brick. I also designed the soft jaws to hold this bad boy. I await the stock to start machining.

www.chrislivengood.net - for my projects and musings.

sav0r

Impeller done. I was waiting on some new soft jaws that I will machine to reflect the cover. They will hold the cover as I machine it in the B side operation, they arrived Friday. I go to put them in the tool box where I keep all my machining stuff. Well, I already had two sets of soft jaws of the same dimensions. I just assumed I used my soft jaws up, I was mistaken. I could have made the cover three weeks ago. 

:help:

Anyways, the cover is inbound. Everything is in order.

The impeller isn't perfect, I find it hard to get programs perfect the first time around, but I never intend to make another one of these and it is good enough. Stock impeller on the side for comparison.

www.chrislivengood.net - for my projects and musings.

pidjones

Nice! I hope this takes care of the temperature problems.
"Love 'em all.... Let GOD sort 'em out!"

sav0r

Fingers crossed!

Between this and the extra inline radiators we are hopeful. We weren't that far off, just marginally so. An overheat is an overheat though. On regular race tracks the car sits on the thermostat basically, so we are over cooled for anything with a decent average speed.

We reworked all the "tube nuts" on the head as well. There is a lot of interference of the nuts against the head and cylinder and as a result there is no way they achieve accurate torque with the torque wrench. So it is clear some of the lacking ability to hold water pressure is related to that. That said, we don't want to over heat at all.

I had hoped to machine the new cover yesterday but the F1 race was a real blast and the F1 watch group in Pittsburgh ended up being a little too fun. So I made some ribs and hung out instead.
www.chrislivengood.net - for my projects and musings.

sav0r

I got the soft jaws machined and the side A on the pump cover machined yesterday. Everything is going to plan. I just need an hour or so to do side B and the cover is done.

Dave (my father) continues to chug away at the conversion of the Express into the Grumman body, I don't see anyway we will have it even drivable for the Grand Prix in July. Dave says otherwise. The best part is that the fuel return line was rotten and was just dumping fuel onto the ground while driving, most of the steel fuel lines need replaced. It's 2008 that we bought new and maintained well... Or so we thought.

The Express is body-less and the Grumman body is getting fitted in various small bits. We adjusted the motor mounts to change the transmission angle slightly, worked on rearranging the radiator and intake, lowered the fuel tank, and are working on fitting a different exhaust. It is an interesting conversion to say the least, something we aren't exactly well versed in. One pic below, it really shows what is the base of the Express and what will be the underpinnings of the Grumman. I am working on arranging tow vehicles for the season...

New Triumph (larger volume) brake calipers are going on the race car and we rearranged the pedal ratio as well, in part thanks to some information we reviewed here on the forum. I could lock them up, but the pedal was woody as all get out, not great. We have a good 10 seconds just in squishing brake zones into appropriate distances at the PVGP track. Then there is another few seconds in better tires, better carburation, better driving, and of course a lack of overheating (it better f'ing be solved). We will probably go way faster and then break something new every session, lol. According to the data, if we can realize these improvements, we will easily reset the all time lap record. According to reality, it will be hard work.



www.chrislivengood.net - for my projects and musings.

sav0r

#126
Job well done on this cover, I reckon. It will be on the car at the bottom of the engine, above a sub frame, and will be seen in 3 years when we need to take it off again. lol

www.chrislivengood.net - for my projects and musings.

sav0r

I got a call from my dad a bit ago. The left rear brake line fell off the Express when he was trying to drive it under the Grumman body. The Grumman body is currently suspended on a 4x4 frame in my father's yard, and since the Express weighs nothing without the body and all of the interior the thing was just spinning the rear tires with the open diff. Well, the traction control apparently kicked in and blew the brake line when it was attempting some sort of stability control or god knows what. He drug it under the Grumman with his Kabota tractor. He thinks the body is going to fit, but the passenger side front seat is iffy because the door is there. He's determined to at a minimum have the body fitted and the vehicle drivable by July, as to tow to the Grand Prix. Pretty optimistic I'd say.

We will see though.

www.chrislivengood.net - for my projects and musings.

sav0r

The body and chassis work perfectly. The Grumman is all together. Dave says he needs to weld in various attachments and remove the body once more. Even if the Grumman van isn't complete it will tow.

For the race car I've ordered tires, we fitted the new brakes, and have adjusted the brake pedal motion ratio. Let's hope we gain. Proper testing sessions are looking less likely with the tow vehicle still underway. I have several formula car events as well as trans am events in the meantime. It will negatively change our testing but positively change our budget. Not sure how I feel about it all. I need to get a few karting days in to bone up on my decrepit driving.

Anyways, we push on.
www.chrislivengood.net - for my projects and musings.

sav0r

#129
We haven't spent a lot of time on the car, but we have done a few small things. I've got the head and am going to change the squish a bit. We will lose a bit compression but we were slightly higher than we wanted anyways. We aren't a 100% sure we didn't hurt the engine last year, but we've decided to run it as is. If she blows, she blows. We are thinking we may have stretched the rods, but without a full tear down it is tough to tell. We know the squish got smaller, so... With the overheat maybe the gaskets settled, or an over-rev made the rods get a bit longer. We will adjust the squish on the mill to get it back to where it should be and hope for the best.

The new brakes are on, the pedal feels like it will actually work and modulate, but time will tell. I have been hunting for tires for this thing, hard to find as we use odd wheel sizes. They also have to be grooved as it is a vintage car, making it more complicated. I am hoping I can swing a set. I had a bit of a set back with my business and lost several grand of what would be funding for this program just in last 10 days. So I am trying to work on that and produce some replacement revenue. Also, finding a decent medium Special Applications 2020 helmet has proven difficult. I ended up buying an Arai, which traditionally are my favorite lids, but the wait times puts delivery for the helmet at the Monday after the races have concluded. Fingers crossed they deliver a few days early.

The Kerbside isn't even close to being done, however, it is road worthy! State inspection to get done in the next week or two. All the inspection required items are good to pass. So once the plates show we will take it for inspection. We registered it as the Chevy Express as that is the vin on the chassis. Let's hope we don't get too much hassle at the inspection station.

The windshield is out in these photos as we were finalizing the windshield wipers. It will use the Express wipers hung from above. We hope to park the wipers vertically, but we aren't sure we can do that just yet. They may end up horizontal at the top when parked, it just depends on what trickery we can do with the existing setup. The nice thing about the Express wipers is that they tie into the Express controls, so we will end up with modern wipers in addition to the modern chassis. For a while we were thinking we would just tie in the old wipers with a toggle switch, but now we are spoiled with delays and speed adjustments.



www.chrislivengood.net - for my projects and musings.

m in sc


sav0r

Thanks! It's been quite a project. The entire front clip comes off because that's the only way to service the drivetrain. It is tight under there. We tilted and lowered the entire drive train to fit it, and we had to rework all of the fuel system, exhaust, and various accessories. The hvac does not work at this point, lol. Windows down for the summer trips, hopefully no winter trips until the hvac works again. It drives like shit unless we have a trailer on it. It is sooo much lighter at this point, based on ride height we are guessing about 4000lbs, meaning 2000 lbs. lost give or take. It is way over sprung for normal operation. Of course some interior will help with that, but we aren't there yet.

I forgot to mention we finished up the half shafts for the race car. I wanted to make some really neat large OD aluminum shafts but my old man nixed that. He turned them out of some nice thick wall stress proof steel and welded them all up. They should be way overbuilt, not exactly what we want with a 1000lbs. race car, but Dave does what Dave wants. At this point I am in no position to argue. I will have the head machined today or tomorrow. I finished the programming last night. We assemble the motor Saturday. I just hope I can get us tires in the meantime.
www.chrislivengood.net - for my projects and musings.

sav0r

We have had a bit of a change in philosophy on the cylinder and head. As mentioned we aren't too sure why the squish reduced. It didn't change much but any change is odd. I touched up the squishes changing the squish angle 2 degrees on the inner half of the piston to make the squish diverge from the piston crown a bit. Getting this setup was tricky. It relied on the fixtures from 2.5 years ago, me remembering how they all worked, and then just fudging stuff around until I was able to just touch the squish. 2 degrees at that width meant about .008" of material at the corner of the squish. Not much, but just what we want to see on the solder. We are going to do another head for sure.



Then we threw some pockets on the water passages for o-rings. This allows use to energize the gaskets from both the bottom end upwards, and top end downwards. We hope we eliminate any potential sealing issues there. We think we had a minor leak there.



The top end is now on the motor. We will pressure test it soon. We found a crack in there rear tripod that carries the spool and bits for the chain tension and drive train. That will come off for repair. We also started replacing rear rod ends. At least 6 of which were in bad shape.

Things are coming along well!
www.chrislivengood.net - for my projects and musings.

pidjones

They say if you aren't breaking things, you aren't pushing hard enough. Sounds like you are getting there.
"Love 'em all.... Let GOD sort 'em out!"

sav0r

Well, this will be try 3 with this car at the Grand Prix, and year 4 developmentally as we missed '20 due to COVID.

They say third time is a charm, but historically we have been excellent at breaking things. Maybe if we have a bunch of applicable sayings we will convince ourselves into success. I'm not sure if we are getting to the point where things are sorted or if we are going to go faster and just break more shit?

Anyways, the new inline coolers are in the pods. I finally got the dash setup so I am hoping for data this time. I just need some corner velocities to look at so I can work on my driving. That's all I ask.

Tires remain the big hold out. The rest of the pieces are falling into place. I am going to look into tire treatments. They are very common on dirt tracks and there are a ton of dirt tracks around. These tires look okay, but there's no way we don't have several seconds per lap to gain in a new set. They are just hard to find. Apparently Avon is having troubles getting rubber from Ukraine... Great.
www.chrislivengood.net - for my projects and musings.