KA Rebuild Questions

[aleph1]

SO! A couple days ago I did my compression and it hit from 100-125 across all cylinders, which was kinda of odd cuz my KA was rebuilt about 16Kmiles ago. I have come to the conclusion that it was most likely a "tijuana re-ring"

Anyway, so the engine in its current standing is not ready for a turbo, so I decided to just go ahead and rebuild it the right way again.

1- I want to get forged pistons. The Ross set on Ka24de.com looks nice but my car will be a daily driver hitting from 7-12psi and Im not sure if the 8.5:1 compression will be good for my needs. I was hoping to keep stock compression, since Im not planning on hitting over 1bar at a very max. (91 octane will be the main source of fuel (98% of the time), maybe a bit of 100+ just for fun)

2- When I take the engine to the machine shop, what "extras" should I invest in? I am definitely thinking of a full balance. But what about mangafluxing, shotpeening, etc?

3- As far as the valvetrain, do I need new valves, springs and retainers? My car has 170Kmiles on it and im sure it has had the same valvetrain the whole time. If I do need new valve parts, should I invest in the setups they have on ka24de.com? The stiffer dual springs/titanium retainers and SS/Nitride valves.

4- As a rough estimate (people with built KATs help me out here), how much can I expect to pay for what I am looking to do, all together? Including new head/main studs (OEM Nissan), bearings (nismo, if I can find em), all the parts from above, timing kit, maybe oil pump, labor, etc.

PS: Anyone know a good shop in the Denver area??

Thanks for your sage-like advice in advance. =D

[Checkered-Member]

For 7-12 psi you should keep your stock compression as you will make more power and better engine response

Full balance is not necessary, especially on a low revving engine like the KA

a good head P&P never hurt anything.

About the valvetrain, if it’s in good condition, there is no need replacing it

[TrunkMonkey]

SO! A couple days ago I did my compression and it hit from 100-125 across all cylinders, which was kinda of odd cuz my KA was rebuilt about 16Kmiles ago. I have come to the conclusion that it was most likely a "tijuana re-ring"

did you do your compression check correctly? just double checking. there's no need to spend money on another rebuild if you don't need it.

-demetrius

[aleph1]

ya I did it exactly as the FSM says. plus I can tell one cylinder (#1, got 90psi dry, 110~ wet) is low cuz my idle reflects it, while at speed the rest of the engine pulls the weight.

[IvanAtSPRacing]

I would think about a leak down test. For your pressure to only jump 20 psi wet seems pretty low for it to just be rings. A leak down test will tell you how much pressure you have lost in percentage and where its going to. Another thing to note would be any little piece of ANYTHING that may have gotten into the cylinder when you pulled the spark plug out can get caught in between the valve and seat and you will lose compression. I have seen it time and time again where one cylinder comes back bad so we put a spark plug back in and run the car for a bit and check it again. 9 times out of 10 your money the second time.

If you do end up rebuilding the motor, I would also have the head gone thru. Get a valve job and new seals. New timing chains, and oil pump. With 170k on the motor, I would freshen up all the wear items.

[andrave]

how much is a valve job anyway? I was thinking about getting one but I'm short on cash and need to get the engine back together. it will be in the shop for hottanking and honing anyway tho...

[Nathan]

Full balance is not necessary, especially on a low revving engine like the KA

Wrong, it might not be necessary if you were using stock pistons and just honing and putting new rings in, but since your planning to change pistons there will be a significant weight difference between the ross's and the stock ones. Because of this, the bearings and rotating parts will wear out quicker. Also, a well balanced engine will rev freer and make more power. Here's a good article on crankshaft balancing: http://www.442.com/tech/balancing.html

Also, you can expect to spend between 600-1000 dollars at the machine shop to have a decent rebuild done. Mine was about 700 and included boring, honing, decking the block, balancing the rotating assembly, bearings (clevite 77 = goodness), and assembling the short block. They checked all the clearances etc. to determine the right bearings for me and luckily, managed not to have to line hone or machine the rods, which kept the cost down a bit.

[aleph1]

Thanks for all your help guys, keep it coming. =) I don't really mind rebuilding my engine for boost, Ill spend the money. Besides I know for a fact that the original pistons where reused in the previous "rebuild".

Just some details I want to get worked out.

Clevite 77 vs Nismo on the bearings (main and/or rod). I know the Nismo ones have a groove to keep oil in when the oil sloshes due to G forces, don't know much about the Clevites, details on the rep for them and benefits?

"Decking the block", please explain this phrase. I've heard it before but I have no idea what it is and its purpose.

As far as timing and gaskets sets are concerned. Any advice on brands to go with for my KAT?

Should I reuse my rods? I hope I can, cuz new rods would add significantly to the cost.

[Nathan]

Clevite 77 vs Nismo on the bearings (main and/or rod). I know the Nismo ones have a groove to keep oil in when the oil sloshes due to G forces, don't know much about the Clevites, details on the rep for them and benefits?

I just know that the clevites are very well made and good bearings...I really dont know anything about the Nismo's so I cant speak for them. I'm sure they are very good as well though and I wouldn't hesitate to use them in my own engine, oem ones have proven to be good so nismo's should be as well.

"Decking the block", please explain this phrase. I've heard it before but I have no idea what it is and its purpose.

Decking the block is where they take this huge machine that actually goes across the top of your engine block and shaves the top layer off to make it smooth and ready for a good seal with a new headgasket. I had it done because the top of my block had some pitting on the surface and I felt it needed it. A very small amount is all that is necessary, mine was .004 inches if I remember right.

Should I reuse my rods? I hope I can, cuz new rods would add significantly to the cost.

You can re-use your rods, just dont go raising your rev limit too much....they are forged rods from the factory, but they are a bit spindly imo. Just make sure the machine shop checks your rods and rod journals to get the right bearings, dont let them be lazy and just order "standard size" bearings or some crap. Same goes for mains.

[andrave]

someone tell me how to check the size of the bearings.

[Jookmasta]

not to hijack the thread, but any idea on the cost of honing an intake mani and would it make that much of a difference? i ask because i happen to have an extra intake mani that was MILDLY ported and polished.

[aleph1]

anyone know where to get 9:1 or 9.5:1 pistons? Ka24de.com only has 8.5:1 in stock and would cost extra to get them to the other compressions.

[aleph1]

I called a local machine shop and got a quote for pretty much the same services as what Nathan got and it was 949...a bit expensive...Its hard to find machine shops around here though.

[Nathan]

I found that pricing varies a lot, I got quotes for up to 1800 or so The highest quote I got was from Rebello Racing

[aleph1]

OK! So I decided I am gonna just go ahead and get the 8.5:1 Ross Pistons because I heard they are very good and it costs 100 bucks more to make them any other spec due to it being a custom set. I figure Ill just run 10psi daily on them, which should be fine. Anyway, my question is this...

I need to and will rebuild soon (within the month), but currently waiting for more money and WDs kit to be released to go turbo. So my KA will have 8.5:1 compression, a whole point lower. Is this safe to drive around NA with that setup until turbo? Do I need to make any adjustments or anything? Can I run lower octane since its not turbo yet??

thanks

[casman86]

It would be extremely safe to drive with the 8.5cr N/A. Would be really slow! Oh well though, it will give you more motivation to complete the turbo setup.

[Nathan]

I would wager money that you wont notice the difference in a FRESH 8.5:1 motor and a old tired 9.5:1 It should be just fine!

[huguetpj]

I would wager money that you wont notice the difference in a FRESH 8.5:1 motor and a old tired 9.5:1 It should be just fine!

I'm with Nathan here. I didn't feel a thing when I drove around for like 3 months 8.5CR in NA trim. I only felt the better flow of the port/polished head up high.

[Aaron_9349]

For reference, Wiseco and CP both make 9:1 Comp Pistons for our engine. I actually have both sets and can't decide which set to use. Probably go with the CP's. I bought the CP's and the Wiseco's were shipped to me on accident when I ordered a gasket set.(FREEBIE) So, I'll be selling one of the sets soon. The Bore is 89.5 though. My pistons are going in in 3 days, so I have to decide soon. I was gonna put the other set up on ebay. I'd like to get $400 for the Wisecos plus shipping. Yet, still unsure which will be better.

Let me know if your interested ( or anyone is) I was gonna post a thread on which one to pick, but might not have enough time. They'd be used with crower rods too. Either way, one set will be up for sale.

Thanks

[yashin]

Would it maybe be a good idea to get lower comp. forged pistons, since that seems to be what most places carry, and then simply use a different thickness headgasket to raise compression?

[TrunkMonkey]

Would it maybe be a good idea to get lower comp. forged pistons, since that seems to be what most places carry, and then simply use a different thickness headgasket to raise compression?

no.

just have custom pistons made for the compression ratio you want. 9 times out of 10 it doesn't cost much more than the off the shelf stock they have.

-demetrius

[aleph1]

[QUOTE]Originally posted by yashin "]Would it maybe be a good idea to get lower comp. forged pistons, since that seems to be what most places carry, and then simply use a different thickness headgasket to raise compression?

I always thought the whole headgasket compression trick was to LOWER the compression for more boost? Is it possible to make the gasket any thinner to raise it? (not that I would)

[aleph1]

For reference, Wiseco and CP both make 9:1 Comp Pistons for our engine. I actually have both sets and can't decide which set to use. Probably go with the CP's. I bought the CP's and the Wiseco's were shipped to me on accident when I ordered a gasket set.(FREEBIE) So, I'll be selling one of the sets soon. The Bore is 89.5 though. My pistons are going in in 3 days, so I have to decide soon. I was gonna put the other set up on ebay. I'd like to get $400 for the Wisecos plus shipping. Yet, still unsure which will be better.

Let me know if your interested ( or anyone is) I was gonna post a thread on which one to pick, but might not have enough time. They'd be used with crower rods too. Either way, one set will be up for sale.

Thanks

I've heard mixed reviews on the Wisecos...never heard anything about the CPs, I did check Race Engineerings site and saw those pistons. I have just heard all good things about Ross and decided to just go with them. Plus 8.5 isnt all bad, its designed to allow more boost, so thats just what I will do =)

[TrunkMonkey]

Is it possible to make the gasket any thinner to raise it? (not that I would)

yes.

-demetrius

[aleph1]

Just a general update on my situation:

At roughly 50% of all stop lights my car stalls (hovers around 200rpms and then just dies all within a matter of seconds). Probably due to cylinder 1s ultra low compression, since while during motion it drives fine.

Anyone know where to get OEM head and main studs? I found rod bolts and nuts, just lookin for these now...

[Aaron_9349]

I just listed my set up on Ebay and they didnt sell. I have the OEM ones still, replaced with the ARP's. They're used but nothing wrong. Just pulled them out while doing the rebuild. $20 plus shipping if you want them.

[aleph1]

Youre not supposted to reuse them because they stretch. I need NEW ones.

[deviousKA]

I can get oem style replacement headbolts, new. I dont know if you can order them directly, but here is my distributor. http://www.rolmfg.com

much cheaper than direct from nissan.

[aleph1]

How much?

[deviousKA]

Ok only price i have with me now is for the ka24e ones, but they are $40 per set. I assume ka24de price would be little difference.