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Man that sucks, def had it running good up top form the looks of it. Guess its a good thing you decided to keep that 4.8 after all huh.
Sure does! Glad it happened in a way too. It made me get off my butt and make some necessary changes. Also let me take a good look inside the motor.
The converter needed to be restalled. I wasn’t going to get anywhere pulling mid 1.4x 60’s. This car should be doing 1.2x 60’s! My last 2 runs would have been a 8.50 and an 8.44 with a 1.25 60’!
Also the 5.3 had some fine alum flakes in the filter the last few oil changes. It was uncovering the pickup on the launch pretty good. Even with 8qts in the pan! ! I bought the Improved Racing crank scraper and baffle setup with the trap doors for the F-body oil pan. Hope that takes care of my issues there.
Last edited by Forcefed86; 07-16-2014 at 08:25 AM.
4.8 short block all cleaned up and ready to go. Waiting on my degree wheel to arrive so I can double check the cam. Can't believe the amount of carbon and crap that builds up on these pistons. Cyls/bearings all looked great. Gapped rings to 20/24 and slapped everything back together.
Takes more time to clean everything that it does to assemble the motor.
Tore the old motor down as well. I don't know if my oil pickup was being uncovered or not. All the bearings with the exception of the #6 rod bearing looked great. The #6 was eating itself. Not sure why. It looked great when I assembled the motor.
Last edited by Forcefed86; 07-20-2014 at 09:54 PM.
Got it all back together and running. 4.8 felt pretty lazy down low compared to the 5.3. Felt pretty quick at 20lbs though. In town I’m really limited on places to “test”. On the way to the track was the first time I opened it up. I was getting a crank/cam sync error at anything over 5k. I had been wanting to switch over to the MS3X platform and instead of trouble shooting it, I decided to just pull the AEM and install the MS3X. Got it all wired this weekend and got the engine to run. Need to seriously work on the tune. Can’t seem to get the AFR’s under control. Pegs the WB02 constantly. Need more seat time with this MS stuff.
So I sold off the AEM ems and installed the MS3x megasquirt box. So far so good, I really like it. I honestly don't see what a holley can do that this unit can't. At $650 new it seems like best deal by far IMO. Sold off the AEM but I have my bare bones standalone harness with factory plugs if anyones interested. It's in great shape and is about 1 year old. It was created from scratch, not a reconditioned harness. Has fuse block and main relay built into harness.
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Wired up these nice little fuse/relay blocks sold by the guys on boostleash.com. Pretty happy with the quality of them. Made the MS3 install VERY easy.
Had the 4.8 all ready to go for next weekends TNT. Noticed my brakes were a little shaky braking at high speeds. Took the wheels off and the both forward discs were all cracked to hell. Looks like they all cracked right along the drill holes. I'm going to throw on an OEM set till winter and address the brakes in the down season.
Last edited by Forcefed86; 08-17-2014 at 06:38 PM.
YOWWZA! Glad you took the time to investigate. What an engineering picture perfect example of stress riser failure, every crack is from the hub, straight through the 1st drill hole of the 3 hole sets. Glad you caught it before the disc pieced out!
Finally got the new rotors in and installed. I went with the 14 blade stator on my converter, it was a 17,
I’m lucky to see 2700rpm in the foot brake and build zero boost. I’ve pressure tested the cold side. And gone over my Vband’s on the exh. side and found no leaks. Removed and bench tested the WG, all seems to be in order.
Car acts like it’s got a massive exh leak, but I think the converter may just be WAY too tight for the 4.8. With the 2 step going and -20* of timing I can make 4lbs and barely hit 3k rpm. When I release the brake boost falls to 2ish lbs and the rpms just hang at 3k for 2.5 seconds before boost comes on hard at 4k. 4k+ every things great, car feels good. My minivan could take it before that point. Tried up to 25* timing in the lower RPM and 12.5-11.0 AFR ranges. Nothing seems to help. I also am not running HYD fluid this time. Straight Synthetic ATF this time around.
I had planned on building a 6.0 for it anyway, so the converter may work out in the end, but I wouldn't suggesting going anywhere near this tight with a 4.8.
We've tried up to 40* timing to get it over the hump and start building boost, you never want to pull timing with a tight converter, you need the timing to make the power to push thru the converter.
We've tried up to 40* timing to get it over the hump and start building boost, you never want to pull timing with a tight converter, you need the timing to make the power to push thru the converter.
Appreciate the input, but I don’t completely agree. Advancing timing past a point isn’t going to make any additional power. All your doing is lighting off the CC mixture with the valves hanging open and sending combustion into the hotside. I’ve tried 40* adv. Retarding works better in every setup I’ve built, including this one. From what I’ve seen, not retarding the timing enough is usually the problem. This just adds some additional heat and is slow to build boost.
Either method works, but retarding has always built more boost in my case. (harder on things as well) -20 degrees built slightly more boost than 40* adv. in my case. I still only see 3krpm and 4lbs of boost. Once the T-brake is released the timing is back to “normal” at 24* or so. The revs and boost drop at this point and the car bogs until it hits 4k. Then it lights off and feels great. Not sure if the 4.8 is way done on power NA, or if the converter is just too much for it.
Similar experience with a friends car. 6.0 S475. Put a tight converter in it and car lost a LOT of MPH and ET was off by nearly a second. Put old converter back in and got the ET and MPH back.
Funny thing is that it still got out of vacuum and slightly into boost on foot brake same way as looser converter did but I guess due to the cam being on the large side it wouldn't light at all.
Going to a 4.8 isn't helping you, but your issue in my opinion is the converter. Get it loosened or get a different one.
When you say -20* on the TB do you mean you are pulling 20* from the initial 24* to make about 4* or do you mean your timing advance = -20*? Just curious.
The car I am talking about is a foot brake car but think the cam is a little on the large side. We use the method Turbo D described and it has about 40* of timing to light it. Pushes through the brakes when it starts to come up on boost but I have a feeling it will light pretty quick on a TB.
When you say -20* on the TB do you mean you are pulling 20* from the initial 24* to make about 4* or do you mean your timing advance = -20*? Just curious.
The car I am talking about is a foot brake car but think the cam is a little on the large side. We use the method Turbo D described and it has about 40* of timing to light it. Pushes through the brakes when it starts to come up on boost but I have a feeling it will light pretty quick on a TB.
I'm saying timing = -20*
The MS3 cycles map timing and -20* in pulses. I've seen as high as -40*.
Advancing timing defiantly helps don't get me wrong. Tons of people do it this way with great results. Just not as good as excessive retard IMO.
1.45 mark in this video is a good example. You can see and hear the combustion going off in the hotside.
Finally got a little testing on the 4.8. Only had one good run, then we were rained out.
9.55 @ 144. 18lbs of boost in high gear. 16ish in low.
60 dry shot worked pretty well. I may up the shot to 75-80. Was able to build 13lbs on the brake and hit 4800 rpm. N20 was set to come on at 2900 and off by 4100. At 4180 I was at 6lbs, engine built boost on its on from there. Worth a 1.50 60' and it was spitting rain a bit. Was on a 295 drag radial.
07-16-2014, 08:19 AM
