Suggested short block upgrades for 250bhp

[420sxse]

I am building a spare engine for my s13 that will be turbo'd. Like the title says, I'm not going to boost the piss out of it, but I want to up the power a good bit, into the 200-250bhp range. I was thinking about using some clevite bearings and CP 8.5:1 pistons. Should I upgrade the head gasket as well? I shouldn't have to worry about the stock conrods or head/main bolts at that power level, right? From what I've gathered, my main worries (with the stock block) will be the rings, too much compression, and a tendency to spin bearings under boost. I'm not dead set on using the cheapest pistons, I am just figuring that the more expensive ones are geared towards insane power and unnecessary for my application. Does anyone have any suggestions, recommendations, or corrections?Thanks.Edit: I forgot to mention that I'm using the block off of a '92 DE.

[SeVa-S13]

You can make 250bhp with a 300k+mi stock KA running on 3 cylinders.

A stock rebuild will likely see you safely towards almost 400whp if you can tune.

[420sxse]

You can make 250bhp with a 300k+mi stock KA running on 3 cylinders.

Not for long! lol. I'm definitely upgrading the bearings, though. What surprises me is that you don't recommend lowering the compression ratio.

[MarkEmark]

You can make 250bhp with a 300k+mi stock KA running on 3 cylinders.

A stock rebuild will likely see you safely towards almost 400whp if you can tune.

How many professionaly rebuilt NON-STOCK, well-tuned KA's need to be blown up before this myth is dispelled??? Dammitbobby just posted about how his stock pistons failed at 14 psi; my pistons had damaged rings and ring-lands at only 10 psi from a small T3. Stock pistons cannot handle a lot of power, period, at least not for LONG.

420sxse: kudos to you for realizing the limits of the KA and realizing that there's a huge difference between making power, and making power RELIABLY. If you're going to be rebuilding a short block but are just planning on 250 bhp, I'd go for some 9:1 forged wisecos (IMHO, the cheapest, and best made, of all the options out there), a new cometic head gasket (may as well, because it's not much more than the stock head gasket), new bearings, etc...but if you're going through all the trouble to have a rebuild, why not throw some aftermarket connecting rods in there as well? They are expensive, but you'll appreciate them in the long run. That way, when you get the power-bug and want to shoot for something more like 350bhp (and i guarantee you, once you have 250bhp, you'll wonder what 300+ feels like, your rods will be ready to step up to the challenge.

the 9:1 higher CR wisecos will be better for off-boost drivability than the 8.5 that you were mentioning, especially if you're not planning on running more than 10 psi or so.

[SeVa-S13]

Did I miss a huge rash of built KA's blowing up at 350whp or something? I wasn't suggesting he try to run that much power on a daily basis; but just like there are engines blowing before they should, there are those that go beyond what they're expected to.

[Edub1]

How much of that is caused by poor tuning? Broken ringlands and rod bearings happen a lot faster if timing isn't retarded enough. A lot of guys don't pull enough timing and run rich instead which breaks down the oil and therefore the bearings. An optimum A/F ratio of say 12.5:1 and proper timing will solve most of those problems.

On the other hand, I'm only shooting for 270whp on account of longevity. Over 300whp on a 2.4L - some things gotta give.

[Jookmasta]

im gonna try to stay middle of the road here as both sides have good arguments. poor tuning will lead to a blown engine eventually (whether sooner or later who knows). as for those that markemark speaks of, those were tuned with a jwt ecu or some other type of timing control besides base retarding of the distributor. even fiznat had his blown to and he was running an aem ems. there's only so much u can do.

my suggestion for ur upgrades are to just follow those plans that u said. if u have the cheese, go for it. u will thank urself in the long run as previously said.

[sunnys14]

what about using BTM as a timing retard for about 14psi? isnt that reliable enough too?

[TheOne]

yeh i mean, how is it that some have boosted their ka's with over 200k on the clock with over 200rwhp?, there's many with over 100k boostin too.

i guess some get lucky and some don't, some have taken good care of their engines and some haven't.(previous owners and the likes).

but to each their own, if you want 100% reliability, rebuild to stock or better if you want more power later on, get a good tune and enjoy.

[S14tat]

i would definitly have to say luck has to do with everything. cause there are some really weird situations where it blows up when there isn't any reason for it to blow up.

[MarkEmark]

Did I miss a huge rash of built KA's blowing up at 350whp or something? I wasn't suggesting he try to run that much power on a daily basis; but just like there are engines blowing before they should, there are those that go beyond what they're expected to.

Well, 3 within a one month period (mine, fosters, virus77's) or so I'd say is enough to generalize that KA engines with stock rods really cannot handle that much boost.

If you don't believe that 400whp on a stock KA rebuild is reliable and feasible for daily driving, why would you suggest he keep a stock rebuild? How could that possibly help the guy out in this situation?

You said:

"A stock rebuild will likely see you safely towards almost 400whp if you can tune."

This is the exact myth I'm trying to bust. It's simply not true, at all. I agree that some engines blow before they should, and some don't blow when they should, but any stock engine that handles 400 whp is an extreme anomoly, a complete fluke, and most certainly does not justify saying that a stock rebuild will see you "safely" towards almost 400 whp. An engine designed for 130 whp simply cannot support a 300% increase in power (not to mention, a 230% increase in pressure, if we assume atmospheric pressure of 14.7psig and that it would require ~20 psi to make 400whp)

Edub1: the exact point I'm making is that these engines were well tuned and still blew up. Foster had the AEM EMS (!!!) and made 430 whp before having his destroyed....We all had timing control...when my piston ringlands self-destructed at only 10 psi from a small t3, i was running a JWT ecu, which has notoriously conservative timing. When my fully built engine suffered catastrophic damage, i'd like to add that the pistons, rings, rod bolts, and bearings were in perfect shape and everything had broken in well; when the crank is at 90 degrees there is very little clearance between the connecting rod and the block, and all that it takes is a little bending that causes the rod to kiss the block, and it's all over.

I'm sorry if I'm sounding impassioned, but I'm really starting to take the whole "you can make 400whp on a stock engine" statement REALLY personally, because I was absolutely devastated after my engine blew up and do not want anyone, under any circumstance, subscribing to that illusion.
Modified by MarkEmark at 6:22 PM 4/17/2006

[SeVa-S13]

There's a huge difference between running that much power everyday, versus having a reasonable daily power setting and not being an idiot (stop revving it so damn high) and then turning it up for a dyno or track day.

It's just been my experience that for every engine that blows before it probably should, there are engines that go beyond what anyone thought was reasonable. What's the stock block SR record? Something over 500whp? I've seen an RB20 with crap compression and a horrible tune make 400whp. The only reason that one failed was due to the awfully lean tune. What's the stock KA record anyway? Coulda sworn it was pretty high...

How much power were you making when your engine blew? And it was rebuilt with forged pistons right? I've never been a fan of trying to make any sort of decent power without a tune, and a cookie cutter ECU flash is not a tune.

Of course making any sort of moderate power is never "safe," comparatively speaking; but everyone should know that and realize when they try to push things past what they were meant for, stuff will break eventually.

Of course the highest powered KA I've ever personally owned was a 300whp-ish nitrous single cam, but the thing had 180k on it and was abused by its previous ricer owner. But I know there are others that have gone far above and beyond that and are still doing so. I think a good stock rebuild with a daily low boost setting in the upper 200's with a high boost at around 350-375whp on rare occasion would be pushing it if you wanted the engine to last forever, but feasible. Just stop redlining the damn engines. (Sorry, people redlining KA's is a pet peeve of mine)

[420sxse]

I understand why some get defensive about the KA. It gets more than it's fair share of ****e, especially from people who don't know a thing about it. But going to 250 at the wheels is almost double from stock. That's a huge increase. Now, just taking the turbo components off of an SR and "slapping" them onto a KA will get you about 170-200 at the flywheel, right? Well, maybe more because the KA has a bigger bore and stroke, but it's still not so huge of an increase and is about all I'd want to do without upgrading the internals. I'd still probably want to lower the compression ratio, though. I'll probably get new pistons. Are the SR 8.5:1 pistons forged? If the engine was made with cast 8.5:1 on the SR version, then I could probably get away with forged 9:1's on the KA version. The larger combustion chamber means the temp will be higher, though, so maybe I'll still go with the 8.5:1's, regardless.

[Edub1]

A while back I started a thread called "Longevity Survey." My hope was to keep it going long enough to collect some real data on this subject.

Longevity is always shortened by performance upgrades whether it's a KA or a 426 Hemi. I'd have to agree that anything over about 200HP is going to shorten the life of a KA, with HP in the 300+ range doing so quite markedly. Sure there are people who have pushed 300+ for a little while, but by and large the motor wasn't designed for it and you're lucky to get 50,000 miles at this level. SR motors use a better piston and a shorter stroke with less leverage on the rods.

Perhaps you guys would like to resurect that post and add your experiences.

[MarkEmark]

There's a huge difference between running that much power everyday, versus having a reasonable daily power setting and not being an idiot (stop revving it so damn high) and then turning it up for a dyno or track day.

It's just been my experience that for every engine that blows before it probably should, there are engines that go beyond what anyone thought was reasonable. What's the stock block SR record? Something over 500whp? I've seen an RB20 with crap compression and a horrible tune make 400whp. The only reason that one failed was due to the awfully lean tune. What's the stock KA record anyway? Coulda sworn it was pretty high...

How much power were you making when your engine blew? And it was rebuilt with forged pistons right? I've never been a fan of trying to make any sort of decent power without a tune, and a cookie cutter ECU flash is not a tune.

Of course making any sort of moderate power is never "safe," comparatively speaking; but everyone should know that and realize when they try to push things past what they were meant for, stuff will break eventually.

Of course the highest powered KA I've ever personally owned was a 300whp-ish nitrous single cam, but the thing had 180k on it and was abused by its previous ricer owner. But I know there are others that have gone far above and beyond that and are still doing so. I think a good stock rebuild with a daily low boost setting in the upper 200's with a high boost at around 350-375whp on rare occasion would be pushing it if you wanted the engine to last forever, but feasible. Just stop redlining the damn engines. (Sorry, people redlining KA's is a pet peeve of mine)

Okay, this is what angers me about forums...No one ever admits they're wrong. You said a stock block rebuild should be able to have 400whp "safely," and have since added numerous qualifiers to that statement instead of just admitting the fact that, in its original text, the statement was prima facie WRONG.

You're right, there's a huge difference between being a dyno queen and making x amount of HP for 30 seconds, and actually driving with that much horsepower every day; but the person who started this post was clearly NOT looking for an engine that can hold on to the ragged edge of its limit to make the most amount of hp; if he's considering using forged pistons and a different head gasket at only 250 hp, he's clearly interested in longevity...I don't know anyone who ISN'T interested in longevity or durability, unless they're building the car purely for dyno or drag purposes (and the vast majority of us simply do not have the funds nor time to do so, barring people like Ivan). The stock block records are entirely irrelevant to this post. He's not trying to make the max amount of horsepower before it invariably blows up.

As far as being an idiot and not revving so high, I hope you're not referring to me. I've never over-revved my engine, rebuilt or stock. When my rods decided to exit fashionably via my block, the engine was at 3000 rpm in 5th gear; everyone agrees that is a comparably low RPM. Even with a valvetrain and connecting rods/bearings that can handle it (as mine now can), i'd still not rev past 6500 rpm simply because it's not reliable.

My engine was rebuilt with EVERYTHING sans connecting rods (forged pistons included) when it blew, and was at about 16 psi from a small T3 (>300whp for sure). When the engine was torn down for rebuild the builder pointed out to me that one of my pistons had completely destroyed ring-lands; this was at around 10 psi.

As far as tuning goes, the WHOLE PURPOSE of "cookie cutter" JWT ECU's is precisely that: so the owners don't tinker with the tuning themselves and then end up blowing an engine up; hence the reason why the fuel maps and timing is CONSERVATIVE....Of course the JWT ECU isn't the best "tune," as far as power goes, but if you're defining the best tune as the most power (which will always be under far leaner conditions and aggressive timing than the JWT ECU allows), then the best tune is most ASSUREDLY not the most reliable. The best tune for the max amount of horsepower does NOT mean the most reliable tune. This is a huge distinction that many fail to see.

You admit yourself: "Of course making any sort of moderate power is never "safe," comparatively speaking; but everyone should know that and realize when they try to push things past what they were meant for, stuff will break eventually."

But the fact still stands; you said 400whp is achievable safely on a stock block KA rebuild. This is completely false, and that's all I'm trying to get you to admit.

We need more people like 420sxse on the forums who aren't living under some fast-and-the-furious illusion of being able to create unlimited power on a stock engine designed for natural aspiration and low power levels. Again, let me repeat: I, as well as the vast majority of KA owners, and the person who started this thread, are interested in durability, and longevity; and neither of those conditions result from using stock pistons and stock connecting rods on a KA.

[SeVa-S13]

Oh teh dwama. Some people make the power reliably, others do not. No one should take any opinion on an internet forum as gospel of course, but I still stand behind mine and say that it's possible (is that a better word for you?) to get almost 400whp on a good stock rebuild and have reasonable longevity. You''l have a hell of a time trying to prove that's "completely false," even if yours did blow at a pretty high boost level for a very small, restrictive turbo at the edge of its choke point. (Even fully built engines blow sometime too)

Of course I didn't mean to imply you were an idiot, obviously. Others are and think that redlining in every gear is the way to do it.I said almost 400whp, since we're nitpicking now, and "likely," adding of course doubt.A two sentence post; the first half of which being kind of a joke, but still my opinion; turns into this.

I'm sorry original poster and all potential KA-T'ers; build the living hell out of your engines to handle far more power than you want and spend a ton more money than you should spend for lower power.

[S14tat]

SeVa-S13, i redline my car to 7000 only in first gear at 1 bar becasue i usually catch traction at the last 500 or so rpm and when i shift at that point, i won't break the tires loose going in 2nd.

anyways is it that bad for my car to hit 7000 rpm in first gear? i've been doing it over a year now and i'm wondering if i should keep on doing it. of course once i have traction in 2nd i shift at around 6100 rpm

[DammitBobby]

If you all care to see it I have a data log of my last tune using a Zeitronix wideband. Data log consist of AF, boost, tps and rpms. My car ran fine (500 miles) until last week when I turned up the boost from around 12.5 to about 14.5. I boosted the car maybe 4 times at that level and it was only through a few gears. I didn`t really notice any problems until a few days later when I was setting up my new Altima fans. I say smoke coming from my oil breather. Still don`t know what is wrong with it yet, hoping to pull the motor this week. Actually thought about taking a video of the smoke coming from the oil breather before I tear it down.

As far as RPM`s I ran it up to 6500. There is a lot of theoris about what power levels are safe for a stock block. I am one that belives that the more we share about what works and what didn`t work the better off everybody will be.

[MarkEmark]

I'm sorry original poster and all potential KA-T'ers; build the living hell out of your engines to handle far more power than you want and spend a ton more money than you should spend for lower power.

Yes, and in doing so, have a car that starts every morning you go down to the garage without indulging in pagan idolatry. Is that a bad thing? I'd rather have an engine overbuilt and running a power level safe within its limits for years than one that has more power and runs at its ragged edge for a good month of fun.

Dammitbobby is case in point; and yes, I'd like to see your data log...

[if0rg0t]

I think a good measure of the requirements for stock like reliability with a turbo motor is as follows. Build the motor so that it has a similar MaxHP to CurrentHP ratio the stock motor (basically, the same safety margin that the stock motor has). The stock motor can take approx double the HP. So, if you want to make 250-300HP, you should build it to take 500-600HP if you want stock like reliability - which means being able to last for > 100k.

Does any experienced engine builders with comments on this 'theory'?

[420sxse]

Longevity is always shortened by performance upgrades whether it's a KA or a 426 Hemi. I'd have to agree that anything over about 200HP is going to shorten the life of a KA, with HP in the 300+ range doing so quite markedly.

I will be using this engine as a daily. This is why I'm seriously considering the lower side of my target range. And yes, I think longevity is implied and crucial whenever talking about building engines, whether it's lasting 100,000 miles as a daily driver or a couple NASCAR races (neither is easy to do with 99.8% certainty). I'm thinking about making a true to Nissan KA24DET, which would be analogous to the (later) SR20DET. This means I would: Take the CR down to the same level as the SR using forged pistons (the SR uses forged, right?), use new factory KA rods, cheat and use better bearings, and boost with a t28.

[MarkEmark]

I will be using this engine as a daily. This is why I'm seriously considering the lower side of my target range. And yes, I think longevity is implied and crucial whenever talking about building engines, whether it's lasting 100,000 miles as a daily driver or a couple NASCAR races (neither is easy to do with 99.8% certainty). I'm thinking about making a true to Nissan KA24DET, which would be analogous to the (later) SR20DET. This means I would: Take the CR down to the same level as the SR using forged pistons (the SR uses forged, right?), use new factory KA rods, cheat and use better bearings, and boost with a t28.

You don't need to have the exact CR as the SR, as was mentioned before, 9:1 will be slightly better for off-boost drivability, and people have made 400+ rwhp on 9:1 wisecos (and, again, they're the cheapest, and some of the best out there-wiseco is the only company that has its OWN forging plant). If you have the money, I'd seriously go with upgraded connecting rods as well; it makes sense to do if you have everything torn-down and stripped apart. They were the ONE thing I did not upgrade/replace the first time I had my engine rebuilt, and they were the ONE thing that failed; there's very little clearance between the inside of the block when the crank's at 90 degrees; all that it takes is for the rod to bend a little and kiss the block, and it's all over.

Not to mention, if you do decide to want more than 250 hp (and as anyone who has ever had a boosted KA-T will tell you, they always want a *little* bit more power), you'll have an engine stout enough to handle whatever your fuel system and tuning can handle. But if you are truly going to stay only at 250 hp, rods aren't necessary.

[420sxse]

I didn't see any sponsors selling Wiseco. Where is a good place to get them that won't put me on back-order?

[MarkEmark]

I didn't see any sponsors selling Wiseco. Where is a good place to get them that won't put me on back-order?

I got both sets of mine from http://www.importperformanceparts.net and have had good luck with their timely delivery....Just give 'em a call before you order to make sure they're in stock.

[hannibal]

I'll add my 2 cents.If youre trying to do this on a budget, you dont have to build the block. Dont expect to make 400whp for 100k miles though.

As a rookie, I wouldnt build up my first turbo motor. Bad tuning and lack of experience can destroy that $3000 motor as easily as my stock one. I'd use the stock motor as a learning experience, and spend the money for a full build if (or when) the stock motor dies. I guess that contradicts the 'do it right the first time' ideal, but it just seems more practical (and cost effective in the long run) to me.

[halnfl]

Buy a spare motor and build it, put turbo on current engine, tune it and try different things with it blow it up, pull motor and go get ur core charge back for the one u had built. That way ur out only a minimal amount of money from the core charge compared to what u bought the used engine for, and u won't be destroying the engine u just had built.

[S14tat]

the SR also use cast pistons, its just that they have a 8.5:1 CR when we have a 9.5:1

on the side note, i must be lucky as hell because i just did a compression test today becasue i went out racing last night and i was beating on the car for the past couple of weeks and i just wanted to see how my engine is doing and i still got 179, 175, 179, 179 across the board.

you think theres some quality issues going on here? like KA's are built better then others from the factory? i mean mines been boosted for 52K miles already and the last 15K miles was at 1 bar, with 6 dyno pulls and 5 1/4 mile runs with plenty of other street races. *shrug*

but i definitly do agree with markemark that we should get a engine that is over built for hte job so we won't have to worry about it breaking. becasue yes even though i am very lucky i still feel like i'm hurting my car everytime i beat on it. and for that sole reason i constantly pay attention to my knock meter whenver i floor it in a warmer then average day, and i'm too scared to take it auto crossing becasue i don't think my engine can stand being in boost for more then 15-20 second spurts without cool down time.

[Craving4Boost]

how is the knock meter working out for you? i just ordered the msd knock alert meter myself. too bad its ugly white...maybe ill paint it black

[S14tat]

i'm using the SAFC II's built in knock alert. alot of people says it gives off false alarms but i swear by this thing becasue it picks up alot of stuff you don't hear.

like if i'm constantly boosting and beating on the car like me flooring it 3 times straight with no cool down time between runs, the SAFC would pick up something, or if i have a bad tank of gas, the safc would pick that stuff too.

so i follow by it religiously and i guess thats how i got my KA to live so long. everytime i reads minor knock, even if its below the limit, i would investigate and try to repeat the conditions to see what was setting it off then correct the problem.

[420sxse]

OK, the peanuts in the gallery are getting stale. Thanks for all the input, though. But why would I go out and destroy an engine? You mean on purpose? That's just silly. If I plan on destroying an engine, I might destroy 2. If I don't, then I might destroy one. As far as the tuning experience gained, well, that can be had other ways, and from other people. I'd rather be SHOWN the right way than learn it through error. Besides, I'm on holdover mode with the old engine till I get the new one done, while chasing leaks in the emissions system, plugging stuff and blocking it off, with 3 time bomb injectors. I replaced one already, It started leaking and may have ruined the headgasket in the back corner, because compression is only bad on #4, but it is steady at like 140. Or the ring could be bad. So this one might be destroyed on me already. She'll last, though. I only live 2 miles from work, and Advance Auto/Zone are both on the way.Here's what I'm seeing as far as the new short block build-up:$440 - Wiseco pistons 75 - Clevite bearings 200 - Nissan rods (I don't know if stress slowly degrades the integrity of the rods over time or not. If not, these would be unnecessary, of course) 75 - Cometic head gasket-------1015 for the bottom end plus what the machinist charges to put it together. Add $440 for Pauter rods, or subtract $200 if I reuse my current rods (a piston/rod combo deal from IPP is $1079, moly coated rings included with pistons alone or in the combo). That's not too bad, considering the rest of the engine is already done, and these are the only parts I still need to get, aside from turbo components, but that's going to be a while more saving. I've been working on it slowly as time/money allows. I'll be installing the engine, breaking it in, running out the last third of my oem generic clutch's life, and probably getting better brakes and a new exhaust (going to need it real soon) before I worry about that, though.
Modified by 420sxse at 6:14 PM 4/18/2006