Compression after 1k boosting!!!

Well as I posted up a while ago, my compression was 165psi across all four. That was with my friends old tester. Last night I tested cylinder #1 with my new tester and it read 190psi! I would have checked all of them, but my starter was going out. I had to tap it for about 5 minutes to get that out of it. Well today I put the new starter in and broke it in with a compression check. Results are:

#1-190psi
#2-190psi
#3-185psi
#4-180psi

This is on a KA24DE with 135xxx miles after 1000 miles of 5-6psi. Most of those miles were under pretty hard driving not to mention coil problems. I am very impressed. I can only explain the higher reading as gauge errors on the old gauge. This was a gauge I bought about a month ago and this was the first test it has done. I have a feeling synthetic motor oil has something to do with it as well. Damn I am happy.:)

thats awesome man.. whats your next mod??

if you want the safc II, kuruma motoring is selling them for about $260 shipped on ebay.. i dealt with them for my suspension and they were great.. 99.6% is their rating which is what i look for when buying on ebay..

I'm considering. I really want to get rid of the PVC intake piping. And if I get a SAFC-2, I have to get injectors and a wide-band. So that package will be about $600-$700. FMIC sounds like a good plan for now with the real intake piping. Thanks for the heads up. Yes Kuruma is a great company to deal with. They shipped my Greddy Type S extremely quick. I ordered my turbocharger about a week before I ordered the Type S and it arrived the same day as the turbo.

nice job.

i had my KA turboed for over a year and over 30K miles running 9 psi of boost, been thru a few over heating issues, and knocking issues, and last month on my compression test

1# 180
2# 185
3# 180
4# 180

stock spec is 179 psi and maximum allowable difference is 14 psi.

i passed with flying colors. now i'm waiting for my ecu and injectors to come back and i'll be on my merry way to 13 psi.

dang, thats awesome guys!! Do you think the SR holds up like the KA does?

Awesome! It must be the synthetic giving such high results. Whats up with the 185s and 190s? Not complaining though. I'm gonna be on my way to 7-8psi woohooo! I only want 13s out of this engine. Whats the word on those Sards anyways? I saw you were having fitment issues?

i sent them back to japan. the guys that sold it to me are goin to exchange it for a set of Nismo/Tomei 555cc injectors. i gotta pay the price difference and shipping fees.

the cool thing is that the Tomei's actually flow 615cc. nice!!!!!

and yes synthetic definitly helps. the car idles much smoother and the oil doens't burn up as fast.

however a SR maintained right with proper fuel will outlast the KA. its just a proven fact. a KA is built freaking strong for a non turbo engine. but a engine thats turboed from the factory would logically and is stronger.

also about the slightly higher then spec's. this is becsaue when i did the test. i cranked each cylinder for 5 seconds. since its not exactly 5 seconds becusae i'm counting my mouth. thats where the slightly higher numbers comes from.

i highly doubt our engines would have carbon build up. that is the only reason why we would have a higher number.

Me too. I just cranked it over for a few.lol SR definately outlasts the KA under pressure. Forged pistons are just stronger than cast. Theres no way around that. Now a KA built to the same specs may be different but that is neither here nor there.

Thats cool that you got the injector dispute taken care of. You're going for 13psi eh? I guess you have to wait for the injectors to come in before JWT will finish your ECU huh?

And just to let you guys know, my engine does blow a little smoke every now and then. Don't automatically assume your engine is shot because you see a little puff of the blue. Doesn't help that I run 5w-30 but I think it is valve seals.

if your valve seals are no good, it would show on your compression test. my engine only blows out white smoke when its really cold outside and on warm up. after it warms up, it stops.

And just to let you guys know, my engine does blow a little smoke every now and then. Don't automatically assume your engine is shot because you see a little puff of the blue. Doesn't help that I run 5w-30 but I think it is valve seals.

yeah...i dont know. keep an eye on it, which im sure you already know but just a reminder. also, blue smoke does denote that oil is being burnt somewhere...

Valve guides maybe?

man, go to synthetic.. i changed at my second oil change since i got my car and it makes a huge difference.. it revs much more smoothly, idles quieter and more smoothly, overall a better feel from the engine.. i use that and 93 octane to keep deposits out of my cylinders.. i'm gonna rebuild in a few months anyways but its good to have a clean driving car.. and who did you guys deal with for your injectors? is there a specific brand thats more favorable than others?

blue smoke? could possibly be piston rings...

Me too. I just cranked it over for a few.lol SR definately outlasts the KA under pressure. Forged pistons are just stronger than cast. Theres no way around that. Now a KA built to the same specs may be different but that is neither here nor there.

Thats cool that you got the injector dispute taken care of. You're going for 13psi eh? I guess you have to wait for the injectors to come in before JWT will finish your ECU huh?

The KA stock pistons are forged, and they dont have to be replaced unless you go over 350-400hp... some people take the stock rods and shotpeen them to make them stronger to hold up to 400+hp , i know a guy who got 400hp on his stock KA engine, i was all holly crap you are nutts!! but we know how our KAs are so strong. I just thing they made these engines for turbo and then just forgot to throw turbos in there on the assembly line... they probably had a little misprint, like KA24DE instead of KA24DET , its ok everyone makes mistakes...

but i personally would change my rods when i turbo mine, because my goal is around 400hp and to be safe..

i still dont know my compression on my KA, whats stock compression? and how much are those pressure gauges?

man, go to synthetic.. i changed at my second oil change since i got my car and it makes a huge difference.. it revs much more smoothly, idles quieter and more smoothly, overall a better feel from the engine.. i use that and 93 octane to keep deposits out of my cylinders.. i'm gonna rebuild in a few months anyways but its good to have a clean driving car.. and who did you guys deal with for your injectors? is there a specific brand thats more favorable than others?

I already am running synthetic. I changed to synthetic at 120k.

he KA stock pistons are forged, and they dont have to be replaced unless you go over 350-400hp... some people take the stock rods and shotpeen them to make them stronger to hold up to 400+hp , i know a guy who got 400hp on his stock KA engine, i was all holly crap you are nutts!! but we know how our KAs are so strong. I just thing they made these engines for turbo and then just forgot to throw turbos in there on the assembly line... they probably had a little misprint, like KA24DE instead of KA24DET , its ok everyone makes mistakes...

but i personally would change my rods when i turbo mine, because my goal is around 400hp and to be safe..

i still dont know my compression on my KA, whats stock compression? and how much are those pressure gauges?

The KA stock pistons are cast, not forged. 400whp on a KA is the result of very precise tuning via stand-alone. The rods are forged and only need to be shot-peened to hold big numbers. Stock compression is 179. I think it is the synthetic causing higher readings. Don't forget to warm your engine up first. I am running 5w-30 so that may be why I get a little consumption. I'm probably gonna switch to 10w-30 next oil change.

hey fanatic, dont you want to buy lower compression pistons if ur upping ur boost that much? i always thought that was neccasary to do when ur getting past 8 psi?

also, since i think you know alot about this stuff, a stand alone system was mentioned. do you need a computer to tune it? from what ive read, it replaces the ecu right? im talking about the aem ems btw.

couple people asked....

the KA24DE is running a 9.5:1 comnpression ratio. good compression for moderate boost. but without a good way to cool the air coming into your engine from the turbo i would not run high boost. in most peoples cases, that want to run high amounts of boost, it is a lot easier and less worries just to lower the compression. as long as yor prevent pinging, you can run a good amount of boost on top of your stock 9.5 to 1 compression ratio. water/alky injection on top of a nice FMIC should allow you to run a good amount of boost. just remember to upgrade everything that needs to be upgraded to prevent detonation also. (fuel injectors are a must)

could poor idleing be caused by bad oil? i just got my car back from it being in the shop for 3 month and now it idles horrable, and every once in awile when i stop it will go down to 500rpm or so, im probably putting cheap napa sinthetic in soon, but will it help me?

so the higher the compression the better? or the closer to the stock compression the better? What happens if its too low?

for turbo, lowering the compression is an easy way to prevent overheating, and i thought i heard something about turbos being more effective with lower compression.. and if its too low then ignition will not be as complete, therefore taking power away

The lower the compression, the higher amount of boost you can run. What it really comes down to is engine strength and precise tuning. I saw a civic in Dsport running 10:1 pistons and 29psi boost! Head design and headgasket thickness can also be factors. If you run a lower compression ratio, you have a larger margin of error when running more boost. Think about it, all you are really doing when you run more boost is increasing the compression. I believe higher compression ratios will also give quicker spool times. Not sure on that one though.

Objective of compression test is to get factory compression.

I believe AEM EMS does require a computer to tune. Its windows based software.

Poor idling is probably basic tune-up stuff. Search for tune-up and you should get some ideas of what to try. I doubt switching to synthetic is going to cure your idle problems. The switch isn't very noticable but your engine will thank you later. Before I switched, I pulled my valve cover off to find scored cam lobes. About four months after I had switched to synthetic, I pulled the valve cover off to find nice shiny cam lobes with no score marks. Its good stuff.

You shouldn't make less power to avoid overheating. Lowering the compression isn't how you should avoid overheating. If you are overheating, there is a problem in your cooling system. It should be fixed pronto because overheating can lead to detonation or preigntion. Neither of those are your friend. And when running highly tuned FI systems, you should run some kind of timing management system that allows you to adjust timing on a curve. I believe Greddy E-Manage has this feature.

The lower the compression, the higher amount of boost you can run. What it really comes down to is engine strength and precise tuning. I saw a civic in Dsport running 10:1 pistons and 29psi boost! Head design and headgasket thickness can also be factors. If you run a lower compression ratio, you have a larger margin of error when running more boost. Think about it, all you are really doing when you run more boost is increasing the compression. I believe higher compression ratios will also give quicker spool times. Not sure on that one though.

Objective of compression test is to get factory compression.

I believe AEM EMS does require a computer to tune. Its windows based software.

Poor idling is probably basic tune-up stuff. Search for tune-up and you should get some ideas of what to try. I doubt switching to synthetic is going to cure your idle problems. The switch isn't very noticable but your engine will thank you later. Before I switched, I pulled my valve cover off to find scored cam lobes. About four months after I had switched to synthetic, I pulled the valve cover off to find nice shiny cam lobes with no score marks. Its good stuff.

You shouldn't make less power to avoid overheating. Lowering the compression isn't how you should avoid overheating. If you are overheating, there is a problem in your cooling system. It should be fixed pronto because overheating can lead to detonation or preigntion. Neither of those are your friend. And when running highly tuned FI systems, you should run some kind of timing management system that allows you to adjust timing on a curve. I believe Greddy E-Manage has this feature.

preach on!!! if your motor is built tough enough you can run high compression with high boost. most drag cars throw a huge blower on top but still run a high compression ratio. this is the reason why they have to rebuild their engines after every track day. ok think about it this way...when you add FI your essentially adding compression to your engine. so lets say your running a 9.5:1 stock compression and 8 psi of boost. that might add up to a total of maybe a 13:1 compression ratio (i had a chart but i cant find it so just take my word i guess). now at that point your putting some good power down. but if your engine isnt built for that 13:1 compression ratio it is gonna destroy itself. this is why people lower their compression so that they can up the boost because it is a more efficient set-up. also, it is a safer and more reliable method than adding a shit load of compression and a little boost. this is also why most factory turbocharged vehicles come with a less than 9:1 compression ratio, its mroe efficient and reliable. there are ways to get around detonation and pinging without lowering the compression but at some point you have to stop.

The difference is when you run a turbocharger, you are making more power by flowing more air unlike raising compression. Raising compression makes the engine run more efficiently by allowing it to burn fuel more completely and/or run higher octane fuel. No increase in displacent(unless of course you oversize which is almost necessary. Try finding a company that makes stock spec high compression pistons).

how much boost is the stock KA able to handle once a FMIC is installed??? just wandering.

a 10.5:1 compression engine is no fun at all, ill tell you that much. :D

No set limit. I know so far the "pro" KA tuners, so to speak, have found that the ring lands give out around 400ish whp. On an average joe car, expect them to hold to around 300whp. After that, your on your own. Expect days of full day dyno tuning and plenty of money.

10.5:1 is no fun.

No set limit. I know so far the "pro" KA tuners, so to speak, have found that the ring lands give out around 400ish whp. On an average joe car, expect them to hold to around 300whp. After that, your on your own. Expect days of full day dyno tuning and plenty of money.

10.5:1 is no fun.


that is very impressive. nissan rules all!!! :lol:

yeah i have a 10.5:1 compression ratio on my z32 n/a. the most i could do is possibly yank the turbos and manifolds from a TT and try to cool that air as much as possible and just hope i can run a few psi. not worth the time nor the money, IMO.

a good FMIC will help you run more boost. however its just one of the things required.

i have a decent sized FMIC and i will not venture past 9 psi with my current setup.

you still need fuel, and some sort of hack into the ecu to accomidate for timing retartation and for fuel enrichment.

my FMIC is good for 400hp but like i said earlier, i'm waiting for my larger injectors, and jwt tuned ecu to come in the mail. then i will know for a fact that i will be safe to run that on my stock engine.

I already am running synthetic. I changed to synthetic at 120k.



The KA stock pistons are cast, not forged. 400whp on a KA is the result of very precise tuning via stand-alone. The rods are forged and only need to be shot-peened to hold big numbers. Stock compression is 179. I think it is the synthetic causing higher readings. Don't forget to warm your engine up first. I am running 5w-30 so that may be why I get a little consumption. I'm probably gonna switch to 10w-30 next oil change.

my bad yea i ment the rods ... :rolleyes:

my FMIC is good for 400hp but like i said earlier, i'm waiting for my larger injectors, and jwt tuned ecu to come in the mail. then i will know for a fact that i will be safe to run that on my stock engine.

nice, what size injectors you going with??? but yeah JWT makes good stuff...definitely worth the price tag.

nismo 555cc sidefeed injectors. when jim wolf flow tested them, they're true flow was 615cc's. its the newer second gen 555cc's with the yellow top. not the purple topped ones.

What are the injectors running you $? And what kind of intercooler are you running? I really want to get rid of my ghetto side mount.

the nismo/tomei injectors runs me around 500 bucks shipped. the intercooler i have is a 27X3X6 inches if i remember correctly. its a wide thick short intercooler. this way i don't have to cut my bumper support. it costed me 220bucks shipped on ebay. the only problem i have with it is that the end tanks are flat and squared. if it was tappered it would've given me better boost response.