running high compression. do you think it will work?

Discussion in '4th Generation (1988-1991)' started by robdob437, Monday 2nd Nov, 2009.

  1. robdob437 Valued Contributor ★ ★ ★ ☆ ☆

    hey guys I've recently purchased a b18c4 bottom. before i start this is what I've got for it.


    YCP pistons. i think basically a replica of the EK9 piston

    full nippon gasket kit. multilayer head gasket

    nippon bottom end race bearings


    b16a1 head with complete 98spec ITR internals

    skunk2 adjustable cam gears

    30thou head skim

    what i want to know really is will this setup work. will a 30thou skim with rep EK9 pistons work with the ITR cams or is this just too much.

    also i will probably be using skunk2 inlet and 70mm TB with a remap

    many thanks rob
  2. captain_sl0w Club Veteran ★ ★ ★ ★ ★

    No-one can say really, the only way is to put it together and see what the P2V clearance is like. I would say that ITR cams would pretty much be the limit on that setup. Ideally you could have done without the skim
  3. MeisterR Commercial Services Trader

    increase compression doesn't always add power, it depends on alot of things.

    When we had our B16 build and the fully forged bottom end went, we put the head on a standard bottom end to see what it will do.

    The fully forged bottom end was 13:1 comp ratio, and the standard is 10:1 (not exact numbers, but close enough).

    We run the setup on the dyno and the standard bottom end didn't "loose" any power compare to the forged bottom end.
  4. robdob437 Valued Contributor ★ ★ ★ ☆ ☆

    yer its annoying because the head is already setup. i have another head coming so i might just have to strip it and use that instead.
  5. captain_sl0w Club Veteran ★ ★ ★ ★ ★

    You need high compression with aggressive cams in order to make power with them. With high-lift and long duration cams you lose a lot of dynamic compression, which needs to be compensated for with a high static compression.

    You need a compression ratio commensurate with the cams you plan on using. ITR cams are mild though, so you don't need such a high compression - so save yourself the trouble

    This is because the cams you were using didnt warrant it, probably the reason your engine didnt make the power you wanted. That or there was a gas flow problem. You make it sound as though you and the builders were all experts and if you couldn't make a powerful B16, no-one could. To me it read as though none of you could find your arses with both hands.

    and its lose not loose
    Last edited by a moderator: Tuesday 3rd Nov, 2009
  6. robdob437 Valued Contributor ★ ★ ★ ☆ ☆

    are you saying save yourself the trouble of switching everything over to a head without a skim or just try and use the head I've got?
  7. captain_sl0w Club Veteran ★ ★ ★ ★ ★

    Im saying don't bother with the pistons; use JDM ITR ones or B16A2 ones which will you give you compression between 11:1 and 11.5:1 with your skimmed head. This gives you the safety margins to be able to use bigger cams later if you wanted. This compression is more than adequate for ITR cams and you have plenty of clearance as well.
  8. Performancetek Club Veteran ★ ★ ★ ★ ★

    This setup would work with no clearance issues, as long as it is just a 30thou skim and its never been skimmed before, and also that the tolerances in the aftermarket pistons are close to the OEM ones.

    Which they probably won't be, someone brought a set of theses YCP pistons to me to get an engine built before, I refused to fit them, they are cheap rubbish, better paying the right money for OEM ones, if you choose to go down that route.

    High compression doesnt = instantly more power, but if the whole setup is well thought out and all the parts are suited to each other then it will definately be a great improvement.
  9. MeisterR Commercial Services Trader

    Well, first, sorry for my grammar mistake and thank you for correcting the important stuff. :Smile:

    Now, I NEVER said me or my Tuner were EXPERTS. I actually said my knowledge isn't in engine building, and I am sure there are plenty of people here with much more knowledge than me regarding engine building (You seems to be Experts enough).

    What I said was what actually happened on the dyno, and I can provide the dyno graph if needed.

    This is not a guess, not a thought, not a theory; but something that actually happened. We drop the compression ratio of the bottom end, we didn't "lose" any power. There are loads of things that could of been wrong with the setup, and there probably was. But whatever it was, it cause us to not lose any power when we drop the compression ratio.

    That was what I said, and that was all I said on my post.

    If any of my post mislead you to feel that I "proclaim" myself as an expert, then I apologize because I can tell you that I certainly am not when it comes to building engine.

    I can just about change my own air filter. :-D
  10. Beau23 Club Veteran ★ ★ ★ ★ ★

    interesting mate doing the exact same build but planning to use different cams prob skunk2 tuner 2's, also have u uprated your breathing system? i went for the b16b inlet etc and mapping on hondata s200, what you gonna be running management wise?
  11. robdob437 Valued Contributor ★ ★ ★ ☆ ☆

    stock chipped obd0 ECU. as pm'ed series 2 skun2 inlet manifold and 70mm TB. have no idea what exhaust manifold yet.

    any sugestions?
  12. Ricky@Race-Tech Commercial Services Trader

    What did you do to the map? I'm guessing you were past MBT with the high comp engine, and just in the sweet spot with the "normal" engine, hence why you lost power.

    Remember, raising compression always gains you power if everything else is equal, if you change the squish area/combustion chamber in doing so, this is where you can make things worse. Along with mapping and other engine specs I presume this is why you didn't notice a change. Out of interest, how much did you change the compression by and how did you do it?

    To the person who posted this thread;

    Make sure you clay the engine when building it, especially if using the YCP's, theres a few little mods your engine builder can do to those pistons what i'd advice.

    When it gets to it, PM me or get the builder to call me. :Wink:


  13. MeisterR Commercial Services Trader

    The big end bearing went on the forged bottom end so we just threw the head on a normal B16 bottom end.

    The forged bottom end use high comp forge piston, where the standard b16 bottom end were all standard.

    Pretty sure the high comp forge piston was 13:1, but can't remember the numbers.

    We swing the cam both way, intake and exhaust. And we added/taken out ignition and fuel on the map, but it just seems to peek and hold at 200bhp no matter what we do to it.

    We did expect to see the power drop when we put the head on a standard B16 bottom end, but it didn't loose any power.

    Things are busy now so we left the car as it is... probably will do more investigation on it in the future. :Smile:
  14. robdob437 Valued Contributor ★ ★ ★ ☆ ☆

    I've decided agianst using the ycp pistons now. I've just booked in the block and crank to be looked at on saturday to see if i can keep the block to just a hone only. i will post up what he says.

    I've been quoted
  15. Beau23 Club Veteran ★ ★ ★ ★ ★

    Can ya shed some light on this for me. I'm doin the same build on my EG. What do you mean by clay the engine, is there any pointers or tips you could give me- cheers liam
  16. robdob437 Valued Contributor ★ ★ ★ ☆ ☆


    this is what he means by claying. also if your doing the build yourself invest in some plastiguage to check the clearance between the crank and the bearings. i think its like a
  17. Beau23 Club Veteran ★ ★ ★ ★ ★

    cheers for the link mate! Just had a read and its gonna help me when building my engine. I'm gonna take it to a engine specialist shop to get some more advice on the matter
  18. Ricky@Race-Tech Commercial Services Trader

    The fact you damaged a bearing as well suggest you could have been way past MBT.

    Also you have PM. :Smile:

  19. MeisterR Commercial Services Trader

    I think that was due to stupidity. :Angry:

    Against my advice someone went and use cheap Shell Helix Oil... then saw stupid oil temperature out of the sandwich plate (which is already cooler than the sump).

    Basically the oil got too hot, it degrade and off goes the bottom end. :Whistle: