I just did something stupid

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May 31, 2006 | 01:20 PM

#21

byebyeL98

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Joined: Sep 2003

Posts: 3,599

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From: Orange County NY

St. Jude Donor '10-'11-'12-'13

Quote:

Originally Posted by ScaryFast

Crap, are my FMS 30# injectors and a 52mm TB going to be enough? Is this going to cost me more than I estimated?

Without knowing everything about the total combo, the 30 lbs. injectors should be fine, but you might find it necessary to move up to a 58mm TB. No need to do it just yet, though - see how it performs first.

May 31, 2006 | 08:11 PM

#22

ScaryFast

Thread Starter

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Joined: Jul 2001

Posts: 4,871

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From: Detroit's West Side MI

Quote:

Originally Posted by sothpaw2

He might. I had my chance and passed on it because for road racing, I want reliability and I am not so use about the 383--you have to have all the right equipment in there--it is custom--you are essentially designing your own motor. I also passed because of expense.

Scary, there's a guy (RichS) here with a nice 396 forged motor that just blew it up at Pocono over the weekend. Says he ran it too hot. Be careful and good luck to you!

Ps--what happened to the 350? What happenend in 1hr? You've had it in there for months I thought?

I already learned my lesson about heat, that's what happened to the other motor. I ran near the edge with the stock motor, often getting over 300* oil temps. I would do a few cool down laps and get back to it. I got the other motor running in April (it was the injectors, BTW) and took it to Mid-Ohio the next day. Oil temps soared with the additional power, but I was too stupid to slow it down. It felt too good to have her out after 7 months. I fried it.

So the car is back in the shop to have a bullit-proof bottom end made. The guy building it does a lot of NASCAR motors, so he's got very nice internals. The goal was just to make it reliable and add a huge oil cooler. But then greed got the better of me, I decided if I'm spending the money on all new internals and machining the block why not do it once.

383 still has nice thick cylinder walls, and appears to be very reliable (although nothing is as good as a 350, IMO). The loading I do to it is all due to high revs and heat, not shock loading like the drag race guys. AS long as we balance the heck out of it well into the 8000 RPM range I should be safe. I also have added an accusump which is another degree of safety to go with the cooler and baffled pan.

What happened to the guy at Pocono, bearing failure?

May 31, 2006 | 08:13 PM

#23

ScaryFast

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From: Detroit's West Side MI

Quote:

Originally Posted by byebyeL98

I hope you're right, I'll send an email to Alvin for a new chip and see what he thinks.

May 31, 2006 | 08:28 PM

#24

the blur

Melting Slicks

Joined: Apr 2004

Posts: 2,775

Likes: 138

From: cyberspace NY

what exactly happened to your bottom end that you say fried from oil temps? I'm a firm believer in mobil1 15w-50, and I run 290 oil temps time and time again. and 8000 track miles later, my LT4 is still together.

Jun 1, 2006 | 10:54 AM

#25

ScaryFast

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From: Detroit's West Side MI

Quote:

Originally Posted by the blur

I always run 10-W30 Mobil 1. The Autometer oil temp guage in the car only goes to 250, that should be enough with the cooler. Without a cooler, it was pegged at 250 after two laps. There's no way to tell how high it really climbed, my guess is way over 300.

Oil pressure at idle was in the 60psi range. At WOT it climbed to the 80 psi range. After the session, at idle I was in the 18 psi range. My oil was close to the viscosity of water at that point. I could smell it, too.

I ruined a main bearing and another rod bearing. Nothing catastrophic, but you can't run a motor with that damage. The main bearing means you have to pull the motor. Since it was out, I decided to rebuild it stronger.

I regularly ran my original motor to 300* with no cooler, pan or accusump and was fine for six years. That means I was much higher than 300* to cook this thing. Pretty stupid, but all I can do is be smarter next time.

Jun 1, 2006 | 11:43 AM

#26

sothpaw2

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Joined: Sep 2002

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From: Maryland

Quote:

Originally Posted by ScaryFast

I guess 250 oil is the safe number, huh? RichS has 2 bad rod bearings in the 396.

My rod bearings were a little worn too when my motor was pulled, would have expected clean. So maybe this says that these motors can't handle the high rpm or power at those temps. I tried to keep my rpm down and my temps never got that hot since I ran on cool days.

Jun 1, 2006 | 02:01 PM

#27

ScaryFast

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From: Detroit's West Side MI

Quote:

Originally Posted by sothpaw2

Honestly, I really don't know what killed the stock motor. I think it was a combination of multiple heat cycles (6 years worth), over revving (I had the rev limiter removed and regularly took it past 6000RPM), and simple years of abuse. My best guess is that I damaged it at Beaverun last September, it was a new track for me so I wasn't as careful to keep track of the guages as I learned the line. I didn't feel the knock (and power loss) until the next time I took the car out, but I was running easy that day so I find it hard to believe that the problem came that time.

As for the last failure, well that's totally my fault. It wasn't borderline hot, it was way past where it should have been. I also had some flywheel vibration which I'm sure helped the situation along.

With the increased cooling, upgraded bearings, and better balancing, I'm pretty confident that this motor will be robust. The builder understands the purpose, his motors are typically run in the 9500 RPM range for hours at a time. And of course, after two rebuilds, my attention is heavily focused on the guages. I'm going to add an idiot light to the oil temp as well.