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Nuclear meltdown!!

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  • Nuclear meltdown!!

    As most of you know...I've been flogging my 'lil Vette un mercifully for the last couple of years. It's SLOWLY been coming around in the ET dept...but keeps getting faster and faster. HP hasn't been a problem!

    I had fuel pump die on me at a recent race. It was "coming and going" as I went down the track so fuel pressure/volume was fluctuating a lot and the EFI safeguards apparently weren't able to kick in and calm down the timing etc. But I didn't know that. All I knew was it popped a couple of times hard and I decided to load it up and bring it home once I determined the pump sounded like it was eating itself. I pulled some plugs- though not all of them (first mistake maybe) and they looked fine. Didn't seem like there was any damage from going lean.

    I sent both pumps to Aeromotive to be rebuilt (great service- in fact it looks like they gave me new pumps) and I spent a gazzilion $$$ buying additional fuel filters and fittings to install before the pump. Never had them before. I re-did some wiring and switched toggle switch to allow me to shut off pumps completely rather than have the EFI control the main one like I had been doing.

    At the last minute I decided to take it to a "Streetcar Takeover" event at Ennis TX. They were allowing some test-n-tune and the weather was fantastic. I had a bunch of last minute issues getting there...battery died and needed replaced etc etc. But I made it. I did notice it had a different sound when cranking and was a little rougher when cold...but I've got all the cold start enrichment turned off and it was cooler than it had been. Probably second mistake.

    Anyway, finally pull to the line....burnout goes well...I launch and it hooks better than it has in a long time (they had glued the track well!) I commence to pulling gears and notice it seems a little weak and then I notice it sounds different. I lifted and coasted through with a 9.53@149 MPH. Folks kept coming by talking about the cool 2nd gear wheelie though!

    Back at the pits I pulled valve covers...all is good. Pulled a few plugs...look OK but something isn't right so I bring it home.

    Compression test confirmed #1 and #3 are dead so I pulled the head(s). Turns out I torched a piston and cut a 3/8" slot in the head between the cylinders. OUCH!!

    I took the heads to Brodix in Arkansas on Monday to let them repair it and freshen valvejob on both. Took a couple of extra days with the wife in a cabin in the woods/mountains. No WIFI or cell phone service. It was great.

    I pulled the shortblock out today and tore it down.

    Good news is the block is fine between the cylinders. WHEW!
    Got one melted piston. The others look OK and no stuck rings or anything
    Have some small scratches in the one cylinder- but they will hone out OK
    All the rod and main bearings look great. Heck I could re-use them (but I won't).

    I've got a piston and rings ordered. I'll get it put back together as soon as parts get here. I "could" use my old Brodix heads...they make just as much power and are sitting on the shelf. We'll see.
    Trying to decide if I should throw a little more cam at it. Hmnnnnnn........

    It's been in "turbo mode" for about 5-6 years now. The first few were mainly street use....the last two have been severe flogging. I'm crossing the line just a hair under 8000 RPM on every pass and even though it's painful to have to fix one occasionally, it's nice to get in there and see all the bearings, crank, rods etc are generally happy.

    JIM

    Last edited by 540Hotrod; 11-25-2017, 11:52 PM.

  • #2
    Man! Sorry to hear about that Jim. Definitely an SOI....

    You're up to the task of fixing it, no doubt. But, the real bummer is that you were likely to get that 8 that you've been searching for so hard! THAT's depressing!!!!

    Now, if you keep the cam in it, then you'd pick up right where you left off. Swap it out and "the cam could have made the difference". Either way, it's a super cool car! Here's a pic that sorta fits right now.


    Click image for larger version

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    • #3
      Mr. Bill!! He's still riding with me!! Along with Buzz and "the feather"!!

      It actually was on a good run...weather couldn't have been better (at least for TX)...woulda, coulda, shoulda.....

      Rings arrived today. Bearings, gaskets and piston on the way!

      JIM

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      • #4
        sorry to hear about that Jim, But that motor looks really good inside, so that tells me, spinning it up aint hurting it, and that is a good thing!!!! good luck, holler next time your going out!!1

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        • #5
          Talked to Bullet today. Old cam is heading out tomorrow to get re-ground! Wink wink.....

          JIM

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          • #6
            LOL!

            Should be interesting on how it performs, and you've got enough prior information to do some pretty good comparisons. Care to share some specs??

            Perhaps we could do a "What do YOU think it'll do?" Thread.....

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            • #7
              Had a long chat with Mark Chacon. Everyone says he's the guy...really good with turbo stuff.

              We actually had maybe a 45min-1hour discussion..so that was cool. He was wearing out his calculator as we spoke. My current cam is a 248/248 on a 114 LSA with .756/.714 lift (1.8/1.7). The idea was to get it to peak HP in the 6200-6400 range maybe and let heads carry the RPM. It did exactly what we planned..so I'll give Chase Knight that...he knows what a Crane lobe will do! As it's turned out it still likes to rev even with the little cam and the heads CAN carry it. I've never measured it but assume there is a LOT of backpressure between the small T3 housings and heads. So backpressure/cam overlap is the limiting factor. My intake is clean inside without any exhaust residue so that's good.

              Now that we have a baseline and know what it does (it's pretty consistent on MPH) and it seems I'm likely to keep revving the snot out of it (despite the BW guys hating me for it) we talked about what could be done to help the exhaust side. He didn't want to go too big either. He also said it's way better to be small than big on a turbo deal especially since the heads are doing well. We talked about advancing the cam ( I had it in straight up to help it carry)....but he still felt we needed to be in the 253-257* range with a 115 LSA installed at 111.5. (depending on what the cores will allow). He felt we could use a 4* split since intake side of heads do so well. Definitely didn't see doing a reverse pattern with these heads. I'm at 20* overlap now and he felt 25* would be the most we could do with these turbos. So likely the new one will be a 253-255/257-259 on a 114...maybe a 115 if core works out. Lift will be similar...though he'd like a little more if possible. Again..using the capabilities of the heads.

              I wasn't surprised. Actually, it's what most other folks were recommending as far as duration range originally...Chris Straub, Cam King etc. But I was working with Chase and as I said...he hit exactly what we planned originally. I think he knows Crane lobes for sure and what they will do. The others were recommending based on max power in a higher range. I'm not sure RPM peaks will move a lot...maybe in high 6000 range....but since I'm up there all the time might as well get back there. If I moved to larger turbos I'd be back in the high 260's again probably and max power out into the low-mid 7000 RPM range with boost. It seems to push things up about 500-800 RPM at least. No way you'd expect a N/A 248* cam to peak past 5900-6000 maybe.

              He said it's hard to find a core these days that will allow a wide LSA and a relatively small duration. He looked through a bunch of them and decided that re-grinding my current one might be best if it will handle it. So we'll see what it will take and go from there.

              Interestingly I spoke to Borg Warner and they said they DO have a T4 housing but it's split internally and wouldn't really flow anymore than what I have now. They are working on some new designs so of course I volunteered to be a test dummy!

              JIM

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              • #8
                Finished disassembly today. Got the pressure washer fired up tonight...haven't used it in a couple of years. Tomorrow I'll start cleaning everything and start the fun task of ring filing!! Oh boy!!

                JIM

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              • #9
                Hope the core gives you what you're looking for.

                It's ALWAYS interesting to read your posts and see the progression. Always informative!

                thanks for that!

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                • #10
                  Got the block honed and cleaned up today. Turned out great...no damage!! Spent the evening setting ring gaps on the new Hellfire rings. Tomorrow will start screwing the shortblock together. Still waiting on the new piston and some Cometic headgaskets. I'm going a little thicker.....I'll explain when I can get some pics. Quirky turbo stuff apparently....

                  Got a call from Brodix last week. Head is an easy fix....it didn't go "soft". So I got it shut down in enough time to minimize issues. They said they want to change the guides on that hole, one intake valve, replace seals and keepers. do repair and do valvejob on both heads. Price was VERY VERY reasonable. I've always liked those guys!!

                  JIM

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                  • #11
                    Great to hear!

                    Ya know, those heads and block have been through a bunch so far.

                    Did you use Cometic gaskets on the last build? How did you like them? Haven't used them, but have heard a bunch about them.

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                    • #12
                      I used Fel Pro MLS. I think they worked fine...other than one blew!! The main reason I went with Cometic was they have more choices in thickness.

                      Got crank in place....rings all installed....went to grab the rod bearings I "thought" I had in stock. OOps.......gotta pick some up tomorrow. Actually could re-use the ones in it...they look fine...but might as well while I'm at it. They've done a good job!


                      JIM

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                      • #13
                        Quick question, do you mic your bearings/journals to check for clearance or use the tape?

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                        • #14
                          I've never been too good with the Plastigauge as far as getting consistent readings. I trust my mics.


                          JIM

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                          • #15
                            Originally posted by 540Hotrod View Post
                            I've never been too good with the Plastigauge as far as getting consistent readings. I trust my mics.


                            JIM
                            I thought you mentioned that you used mics. I always wondered about something with them. The outside journal of the crank is obvious, but I've wondered about the inside measurement. I assume you use a set of "T" bars? The spring-loaded ones that you open to the inside diameter and then lock them in place. My thought was that if you're measuring one and a half thousandths, how accurate can this method be? I mean folks have been using it for a long time, but I wonder about the flat spots on the "T" bar and the curvature of the inside of the bearing. Doesn't this skew the reading a bit? We ARE talking about half, of a thousandths of an inch, after all?

                            I've not used them enough to work it all out, and maybe I'm overthinking it, but with that kind of precision, the reading has to be pretty good, right? The fact that you've done this and, we can all attest that your engine stays together, only proves that you are obviously doing it right. Hence, the question....

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