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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
I haven't updated this thread in awhile, as there has been basically no movement on the motor build until this week. I'll start with my experience with the different shops I have worked with, and then go over the current status of the motor and basic plan going forward.
In January I decided to go with Reher Morrison to build the motor. I dropped the motor off on 1/12 and was quoted 6-8 week lead time. Coming up on 8 weeks I checked in as I hadn't heard anything, and was told they were backed up but I would get an update soon. After a few weeks I called again and heard the same thing. After 13 weeks I had called 5 or 6 times to get updates and was finally told it might be another 8+ weeks. I decided to pull the motor from RM and go with another shop. I understand these delays happen and have no issues with RM, however I do wish the communication had been better instead of me having to constantly follow up with them to get answers.
Anyway, I looked back into HPR who I had considered back in December, and after talking with Anthony decided to drop the motor off with them on 5/18. Had a great talk with him and Erik as we unloaded the motor, very knowledgeable guys and have a cool shop with some interesting builds going on. HPR got right into my motor and opened it up yesterday. The findings are below (as a reminder my issue was low oil pressure while cruising around):
1. #1 and #2 connecting rods have worn away the factory coating and have started to eat into each other. Erik and I believe these can be saved, and re-coated at Calico. None of them look to have gotten hot at this point.
2. #4 main bearing was on the verge of spinning. It didn't knock the tangs off the bearing but as you can see it sure wiped the bearing and the crank. The block will take some time to line hone but should be fixable.
3. Pistons do have some marks in them, and #7 had the worst damage with a few pieces missing and it also pinched a ring on the piston so that one for sure is junk.
4. Not confirmed but pretty sure the crank is slightly bent, mainly from that bearing. Again this should be able to be fixed but I'll have to send that out to be done. Way cheaper than a new crankshaft from GM.
5. The block looks salvageable, #4 main got a bit hot but looks like it can be fixed up.
Once we confirm what is salvageable, Anthony and I will look into what needs to be ordered and spec out a cam, pistons etc. The build is starting to look like a full bolt on, high compression E85 build with supporting mods. I'm thinking about going for a SCR around 13.5-14.
I will keep updating the thread with more information/pictures as things progress, and I'm sure Anthony will be jumping in as well. Look forward to hearing your thoughts! Cheers.
Last edited by parroteyes; 05-23-2018 at 10:26 AM.
I would say you are lucky you shut it down when you did. The crank actually would still turn over, tight...but it did spin.
With all of the marks in the pistons, I would say that engine has had a hard life....or at least a few oops moments given the amount of trash that hit the pistons.
Some more progress yesterday/today, the motor is stripped to the bare block and got cleaned and line honed. Cleaned up well and showed some marks in #7 due to the debris that marked up the pistons, likely part of a spark plug.
The line hone also went well. As mentioned above the #4 main bearing got the worst of it and so that cap took some heat. The caps ended up in spec and straight after the line hone.
Next step will be honing the bore and taking the heads down for surfacing/milling. More pictures below of the cleaning and line honing.
I would say you are lucky you shut it down when you did. The crank actually would still turn over, tight...but it did spin.
With all of the marks in the pistons, I would say that engine has had a hard life....or at least a few oops moments given the amount of trash that hit the pistons.
Small update this week, the crank was sent out to be turned. Mains were turned 0.010 and everything else checked out fine. The motor will be going through the bore hone in the next couple of days and we can order the pistons at that point.
Some decisions I have to make besides cam choice are oil pump and oil tank, if I want to make an upgrade for potential future road racing. I'm leaning towards stock for now, as I will only make it out to a road course a couple times a year.
I have the list of pending items if anyone is interested in checking out the plan for the motor in more detail.
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I am in a similar position and watching this thread. Had my C6Z for three days before the motor seized (never even got a chance to get on it! think rods are galled or it ate a bearing). I am waiting for KSR to pull the motor to see exactly what happened, but had already reached out to a few companies and HPR was definitely the most helpful despite my complete lack of info at the time. Wish they were closer but still may go that route depending on what we find in the motor. Hopefully I'll know more soon.
Good luck with the rest of your rebuild. I may have missed it but are you sticking with a 427 or going stroker? What about compression?
I am in a similar position and watching this thread. Had my C6Z for three days before the motor seized (never even got a chance to get on it! think rods are galled or it ate a bearing). I am waiting for KSR to pull the motor to see exactly what happened, but had already reached out to a few companies and HPR was definitely the most helpful despite my complete lack of info at the time. Wish they were closer but still may go that route depending on what we find in the motor. Hopefully I'll know more soon.
Good luck with the rest of your rebuild. I may have missed it but are you sticking with a 427 or going stroker? What about compression?
Never like to hear a story like that, but gotta make the best of the situation! Make it into the exact beast you want it to be.
HPR has definitely been the most helpful company of all the builders I've talked to (and I've talked to a few). Very knowledgeable guys and I feel like I'm in the right hands with them.
I am sticking with 427ish (once the bores are honed might be a 429). The motor will really be intake limited at that point, not displacement limited. I haven't landed on a final number for compression but looking at 13.5-14. If I'm going past what is safe on 93, might as well go all the way. Let me know if you have any q's, and feel free to PM me if you want to chat more about shops and my experience.
Small update this week, the crank was sent out to be turned. Mains were turned 0.010 and everything else checked out fine. The motor will be going through the bore hone in the next couple of days and we can order the pistons at that point.
Some decisions I have to make besides cam choice are oil pump and oil tank, if I want to make an upgrade for potential future road racing. I'm leaning towards stock for now, as I will only make it out to a road course a couple times a year.
I have the list of pending items if anyone is interested in checking out the plan for the motor in more detail.
If the crank main bearings were almost ready to let go make sure you have the crank checked for straightness, often the heat generated by a main bearing that's about to fail can warp the crank.
- pulled the motor
- darton dry sleeves
- forged rotating assembly including the crank
- rebuilt the top end
- added a supercharger
- reworked the fuel system.
- 900rwhp
If the crank main bearings were almost ready to let go make sure you have the crank checked for straightness, often the heat generated by a main bearing that's about to fail can warp the crank.
Agreed. They also have to be checked / straightened after cutting them too. As heat from the turning process can move the crank around slightly during any repair process. So we check them before and after that process too. Either way excessive heat into the crankshaft is not something that you want to have happen.
Some more progress yesterday/today, the motor is stripped to the bare block and got cleaned and line honed. Cleaned up well and showed some marks in #7 due to the debris that marked up the pistons, likely part of a spark plug.
The line hone also went well. As mentioned above the #4 main bearing got the worst of it and so that cap took some heat. The caps ended up in spec and straight after the line hone.
Next step will be honing the bore and taking the heads down for surfacing/milling. More pictures below of the cleaning and line honing.
From the pictures above it looks like you had the block line honed, I would never do that to an aluminum block with steel or powdered metal caps, it never turns out to be a perfectly round bore, on any LS with an aluminum block with steel or powdered metal caps you want to line bore so you end up with a bore that is closer to a perfect circle. This is why the stock blocks are line bored from the factory and not line honed.
From the pictures above it looks like you had the block line honed, I would never do that to an aluminum block with steel or powdered metal caps, it never turns out to be a perfectly round bore, on any LS with an aluminum block with steel or powdered metal caps you want to line bore so you end up with a bore that is closer to a perfect circle. This is why the stock blocks are line bored from the factory and not line honed.
All OEM GM blocks are line honed including all the LS and LT blocks as well from the factory. You can see the factory honing marks or pattern on them as well when you take them apart.
In fact pretty much ALL blocks aluminum or Iron or multiple material block and caps deals are line honed from the US and most foreign as well as DART and WORLD and RHS and Brodix etc.
There are probably some that aren't but that's why because honing gives you rounder holes and better surface finishes just like on cylinder bores or rod big end bearing housing or rod small end pin bores etc.
It is sometimes a little harder to hone the bi metal stuff but not that hard and some of it comes in .002+ out of round even though it was running alright most of the time. Cutting the caps and re-honing can usually bring them back into spec and inline with each other after the block has stress relieved it's self and moved over time.
Of course if we have something really trashed then sometimes it does have to be line bored first though as in when we put different or totally new main caps on as well. Those have to be line bored and then line honed after since they are not even close.
Most line bore rigs don't leave the best surface finish so the majority of race and oem stuff is bored first to a slightly tighter size and then honed to final size after.
All OEM GM blocks are line honed including all the LS and LT blocks as well from the factory. You can see the factory honing marks or pattern on them as well when you take them apart.
In fact pretty much ALL blocks aluminum or Iron or multiple material block and caps deals are line honed from the US and most foreign as well as DART and WORLD and RHS and Brodix etc.
There are probably some that aren't but that's why because honing gives you rounder holes and better surface finishes just like on cylinder bores or rod big end bearing housing or rod small end pin bores etc.
It is sometimes a little harder to hone the bi metal stuff but not that hard and some of it comes in .002+ out of round even though it was running alright most of the time. Cutting the caps and re-honing can usually bring them back into spec and inline with each other after the block has stress relieved it's self and moved over time.
If you look at any new or used GM block that has not been line honed you will not see any cross hatch pattern that line honing would show, instead it's radial lines as in line boring. Most aftermarket aluminum blocks use a much stronger aluminum and you can get away with line honing, that's not the case with OE blocks.
I think GM and Ford and DART too use some kind of diamond hone nowadays because instead of normal crosshatch it's only a one way pass. All the hone marks spiral through in one direction only.
Update for this week, the bore hone has been completed and the deck cleaned up. Bore was honed .010 to 4.135. Block is washed and bagged up ready to go once all the hardware/rotating assembly/etc. arrives.
Pistons have been ordered and will arrive this week or next. Rods are off to Calico this week and the heads will be torn down.
I have ordered the DSX flex fuel kit and Walbro 450 fuel pump. Still need to decide on injectors and clutch. Leaning towards Monster LT1-S twin and either FIC or ID injectors. Things are moving along smoothly.
I have no insight into the discussion above regarding line honing the end caps, I'll let Anthony chime in there. Pics below of the finished block. She's pretty!
12-08-2017, 05:31 PM
