Tuning my DR750s on Chrome

[anyonebutme]

on the other side of the aurgument, I left my stealth on unsupported wheel bearings for 6+ months, rolling it around, with no side effects. I would still suggest popping the axles back in or get some stubs.

[RealMcCoy]

Does anyone have experience with using bolts and washers to substitute for axles so I can roll the car out? Any guesstimates on sizes?

1/2" by 4" bolts with nuts and flats, and some malleable iron washers...

[kywhitelightning]

To clear the air about the bent rod causing spun bearings, that is false. Ray was spot on with his description. The rod bent, causing the crankshaft counterweight to hit the pin boss and it chipped a little bit of the skirt off. This rod was driven/babied 250+ miles like this to get it back home after the dyno at IPS. There was not one bearing flake in the pan. There was however, the piece of piston skirt in the pan. Here's a pic of how it was rubbed.

I doubt timing up top hurt Chris's, as a matter of fact I have a hard time believing stock timing hurt it at all. I have 750's now with raised compression running 93 pump and 1000ml/min of meth and have done a few pulls above the stock cap of 22*. This was also peaking 25psi and leveling out to 22 by redline. I am also running the chrome software, which I absolutely love, that allows me to make timing changes without readjusting the fpr. These engines have been run hard for years with above stock timing because the second you put a piggyback on it and change the maf frequency, timing is going up. My old 19t setup would see 25-26* and like it. 27 was iffy and 28* caused the failure along with a few other tuning mistakes. I did some pulls prior to the IPS dyno with 28* and it seemed ok but I later found a leaking methanol hose which I attribute a lot of the failure to. The fact that I pushed the car harder even though it was knocking is just bad judgement on my part and I paid my dues for that.

I have been fighting compressor surge since the 750's have been put on though. I'm working on a fix but haven't gotten anything worth posting about yet. Raised compression and 750's may not be the best way to go because they spool so stinking fast. The car was undrivable in the cold. As much as Matt tries to stop people from calling it surge, it is exactly that. When pushed harder and harder it gets more and more violent eventually causing bucking. On the 19t's a simple blip of the throttle and I was good to go again. It's hit and miss with this setup. Even in the warmer temps. I know I'm not the only one with the issue now because Ray just recently had a dyno day where he had to start a pull a little later just because of that. Hopefully, it'll work as it is planned to. I just wonder if my raised compression is an equivalent to the alcohol's effect on tq in Chris's case.

Chris, I hate to see this and I was really excited to get to see your car at the NG. I really hope you can thrash to get it back going again and get it there. Now that you are started you aren't going to want to stop until complete. Good luck with the new rebuild.

Jeff

[NOMIEZVR4]

KyWhitelightning can you please post more details about your car and setup and how you like/dislike it so far compared to the 19T's...nice to see you got the car up and running again congratulations!

[fastfalcon94]

When I built my vr4 it sat outside for about a year without an engine in it. I did bolt the axles back in though so I wouldn't destroy the wheel bearings. You just gotta be careful when rolling the shell around. Do it slowly and make sure the axles won't catch and bind on something. My buddy bought bond auto parts wheel bearings for his dsm and he always had his engine out. He never did this and went through quite a few wheel bearings. Fortunately they had a lifetime warranty so he just kept bringing them back.


I get surge on my dr750s too, but it's very forgiving with speed density. I just stay out of surge by either letting off the gas, or hammering on it when I want to go. It's part throttle where I'll see it. I want to add divider plate going to my front mount, but I'm waiting on another guy on here to do it and test it out first.

[Ninja Performance]

Does anyone have experience with using bolts and washers to substitute for axles so I can roll the car out? Any guesstimates on sizes?

In the past I used large bolts and washers and nuts, currently I have old CV shafts that were replaced in customer cars, I chopped off just the end knuckle and use those.

-Chris

[Chris@Rvengeperformance]

[Chris@Rvengeperformance]

don't worry that oil filter was just to keep dirt out, I don't run those!

[Chris@Rvengeperformance]

I'd love to get this back together for NG, but I have to be realistic with machine shop time. At best the engine will be at Ray's by the end of the week.

Turbos are going out to DR today. Engine is down to the valve covers, should have it down to block tonight. I could just buzzsaw through the tear down, but I bag every bolt and take pictures of brackets so I don't forget how to put this back together.

With just one rod bearing dominated I feel less like this was a tune issue. I'd expect multiple ones to be beat up if the timing was too high or something like that.

The only thing concerning is there is some white residue in the headers, but it looks like that white stuff on the plugs, so maybe that is just from the alcohol.

[Chris@Rvengeperformance]

oh and the turbos look 'ok' to me. There are 1 or 2 micro chips on each turbine blade, but they were too small to even photograph. Looks like normal wear, but I was not brave enough to pull the turbine housing, so I'll leave that to DR to decide.