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-   -   Yes, Another Machine Shop Thread (https://www.miataturbo.net/engine-performance-56/yes-another-machine-shop-thread-102754/)

famousamos56 04-29-2020 06:47 PM

Yes, Another Machine Shop Thread
 
Haven't seen anyone discussing machine shop quotes lately. Finally getting towards pulling my motor and building for boost.

Going for a motor plenty strong enough for 8-8.5k rpm (thinking of running it max of 7800 rpm for safety?) and 450whp (actual power goal is around 375 whp)
Doing forged rods, pistons, picking up a built VVT head used from another member which does need some work

Plan for machine shop work;

Bring them the already(old) assembled head and do the following;
Clean, Tear down, inspect, check springs etc. basic valve seat grind/valve job and then determine what else may need be performed for the head. Quoted at $300 for these basic services, Obviously this price may rise if more issues are found.

Block work.
Bring them torn down block/crank.

Clean Block/Crank = $140
Alignment hone/bore =$180
Cylinder bore/hone =$120
Grind crank $160 (only $60 if polish is all that is required)
Resurface block = $90
Final rise/clean of everything (clean all oil galleys etc.) = $40
Balance rotating assembly = $200-225

so approx $1000-$1150 for the block and head machine work. With possibility for more cost if the head has problems.

I will be reassembling everything. The plan is for them to clean it all up, measure it, let me know what they need to do for bore/hone/sizing/grinding. Order pistons and bearings per sizes they recommend and they do work and size it accordingly.

Am I missing any major items that they should be completing for these goals, if I am going this far, should I have them do anything else that would be worth it at the time for better reliability and or performance?
This is supposed to be a very reputable shop that has been in business for over 60 years - Gunn Automotive in Denver, CO.

Anyone have any recommendations for the Denver area or thoughts on how I am going about this?

borka 04-29-2020 09:08 PM

$140 to hot tank a block? Ouch
what's alignment hone?
$90 to resurface? Ouch

I paid like $180 for hot tank, hone and resurface. That's all my block needed.

Just had a head hot tanked and resurfaced for $83 total.

But machine shop rates do vary.

famousamos56 04-29-2020 09:43 PM

I believe they are hot tanking and bead blasting it from the discussion I had with him. My understand is that will get it fully cleaned up and remove any and all rust etc.

Is that still wicked expensive?

Alignment hone is honing the crank main races on the block. My understanding is it is a REALLY good idea to do if building a motor, and especially if changing studs.

borka 04-29-2020 10:42 PM

I'm not an expert on engine building, I just did a basic rods only refresh.

I guess if they are also blasting and hot tanking, it might be more reasonable.

I'll let others chime in on the high performance building techniques

LeoNA 04-29-2020 11:00 PM

You should clarify what they will be doing for the balancing since it is one of the more expensive procedures. Inline engines have a crankshaft that is balanced to 0. This means they rarely require much if any balancing. It is not like a V engine where altering the reciprocating assembly would require weight to be removed from or added to the crank. I usually spin the crank and then bolt the flywheel on to check them together. My last build I just skipped everything except double checking the pistons and rods. All where very good. You could also do some of the cleaning yourself. Have the mains checked before align honing. If the housing bore diameter is within spec and the cap shift is less then .0005" you could forego that as well. The price quoted for the head work is too low for what you want to do. Labor and parts for a solid head is well over $1k. Springs, retainers, valves and guides are $1k and the labor to do it right is at least $300-500. Good luck.

curly 04-29-2020 11:24 PM

Don’t let them bead blast anything. NOTHING. No matter what they say about how they clean parts afterwords.

you’ll need your rods and pistons at the machine shop for them to properly set piston to wall clearance, and measure rod bores to make sure the wrist pins are good in the rods. My machinist was annoyed K1 had fully machined the rods without knowing the size of wrist pin being installed. If you’re not experienced in engine building, I’d have them grind the rings and assemble the short block.

cpierr03 04-30-2020 11:24 AM

Machine shop prices are effectively useless unless you're quoting your general location. I'm in NY where everything is expensive, quotes for stuff here are usually a fair bit higher than what the Internet says.
EDIT: I now see you specified Denver CO - comparing quotes to other users should probably include their location. For reference a basic head refresh w/ SuperTech heavy doubles was $400 in my area which is a bit of a steal for my location.

Also as I understand it BP cranks are forged so you would probably want to source a new one if it requires grinding.

LeoNA 04-30-2020 03:59 PM


Originally Posted by cpierr03 (Post 1569070)
Machine shop prices are effectively useless unless you're quoting your general location. I'm in NY where everything is expensive, quotes for stuff here are usually a fair bit higher than what the Internet says.

I agree. I have been to many shops or have worked with several in many different regions. Labor and the cost of living varies substantially.


Originally Posted by cpierr03 (Post 1569070)
I now see you specified Denver CO - comparing quotes to other users should probably include their location. For reference a basic head refresh w/ SuperTech heavy doubles was $400 in my area which is a bit of a steal for my location.

The cost of ST heavy doubles with retainers are $450-500 delivered. So that is a very good deal if the springs were included, if not then that is average.


Originally Posted by cpierr03 (Post 1569070)
Also as I understand it BP cranks are forged so you would probably want to source a new one if it requires grinding.

This does not make sense. The cranks are forged and there is no issue with grinding them .25mm undersized.

cpierr03 04-30-2020 09:15 PM


Originally Posted by LeoNA (Post 1569134)
The cost of ST heavy doubles with retainers are $450-500 delivered. So that is a very good deal if the springs were included, if not then that is average.

This does not make sense. The cranks are forged and there is no issue with grinding them .25mm undersized.

I provided the springs and valve steam seals, so it was 400 for labor for a general head refresh along with installing springs, seals, shimming to spec etc.

RE: Crank - I'm not a metallurgist so I'm just repeating what I've been told - a hardened surface gets ground away. No idea if there is any truth to it


LeoNA 04-30-2020 11:18 PM

With seals, shims, spring kit and labor it would be approaching $1K. That is about average for a mild build. The OP wants to 375-450whp which would require a little larger investment. The cranks are not surface hardened and removing .125mm from the surface will not degrade its performance.



Originally Posted by cpierr03 (Post 1569166)
I provided the springs and valve steam seals, so it was 400 for labor for a general head refresh along with installing springs, seals, shimming to spec etc.

RE: Crank - I'm not a metallurgist so I'm just repeating what I've been told - a hardened surface gets ground away. No idea if there is any truth to it


curly 05-01-2020 12:11 AM

You're fine grinding BP/B6 cranks.


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