Daboss

Purchased from tomei stated they were drop in 264 with 8.5 mm lift, they retain vct, idling at about 1000 rpm,don't know what previous cylinder psi was but got 150 psi dry tested with cams installed. Didn't try any dialing in only have an exhaust cam gear cause intake retains vct, manifold vacuum haas dropped at idle from showing -17 on the boost gauge to showing -8 and idle is horrible. Entire car shakes and sputters.

Hey there need some urgent help with my 25/30. I have just installed some tomei 264 poncams and now my car idles like crap. The whole car shakes and vibrates and just doesn't feel right. I have new lifters, upgraded valve springs and retainers, new valve stem seals and the tomei 264 poncams. I have a tomei exhaust cam gear installed with no advance or retard.Controlling everything is a pfc l jetro and I have 700cc injectors. The car revs and drives ok but idle is horrible. Timing is spot on and no matter how far advance or retard ignition timing or add and take away fuel the idle does not get any better. Now don't get me wrong it changes the idle and ratios but the best idle I can get is still crappy. Every video i see or person i ask that has installed these cams say they are straight drop in and do not affect idle like what I am describing, but my idle woes only happened after the cam install. I thought bent valves but got a reading of 150 psi on all cylinders doing a dry compression test. Can anyone give any advice? I am totally stumped and bout ready to go back to the original cams cause this idle just is not right. Anyone with any experience please give some advice.

Want to buy or trade for rb25det modded head. If anybody has a modded rb25det head they want to trade or sell hit me up with specs and a few pics and if it is what I need/want we can work from there.

Between work and weather have not gotten a chance as yet, will try for this weekend and let you guys know results as soon as its done.

Well definately not 9:1 compression in fact I am assuming around the 8:1 to 8:3 range. I used stock n/a pistons with rb25det head and 1.2mm mls head gasket. Exactly what I am feeling. Like I said don't know if my expectations were to high, but it just does not feel right. Feels like my old rb25 and with basically the same everything except a half liter more displacement I should see/feel noticeable gains. The turbo spooling at virtually the same rpm is indication to me that its basically the same as my old rb25. Guess you guys will be able to tell me more after comp test results.

Cam timing was quadruple checked it is spot on. Will do compression test this weekend and let you know the results. What type numbers should I expect going with I built it right and compression is around 8.3:1? Also am I right to assume that there should have been noticeable gains over the rb25 if the motor was built with 8.3:1 compression ratio? It is virtually the same as my old engine which would have been 8.5;1 or maybe even a bit lower as my old rb25det headgasket was a 1.3mm. Only difference would be this engine has a half liter more displacement, which should equate more everything.

The motor was originally a non turbo motor, or so I was told. Is there anyway to tell a non turbo from a turbo rb30? No e85 were I am from. I am running water meth injection in conjunction with USA 90 ron.

Hey all I have finally put my rb30det together and I must say I feel accomplished doing it, but the improvements I expected from it are not there. It still feels like my rb25det. I don't know if it is just me or my expectations were to high but everything feels the same. I expected off boost driving to feel better and have more grunt and low down torque and a massive increase in spool seeing as I went from a 2.5 to a 3 liter while using the exact same turbo and housing, but no such luck. To give a bit of background on the car: I had a rb25 with a few mods,forged pistons, forged rods, all bearings changed to acl bearings, freddy intake manifold, t4 twin scroll manifold with the collector for the wastegate merged so you only use one wastegate, hx 40 with t4 .58 housing, 850cc injectors, ford lightning maf, meth injection, walbro e85 450 lph in tank fuel pump all controlled by a power fc. Never dynoed the car but was making excellent power for me. Boost of about 15psi came on full at about 4000rpm in second from a cruise doing about 2000rpm then going wide open throttle. It lit up the tires doing that in second and pulled all the way to red line. In third and fourth I had strong pull all the way to my redline of 7000rpm as well. Needless to say being lazy I knocked the motor due to lack of oil, so instead of a full rebuild I decided to go rb30. I sourced all the parts I needed and built an rb25/30, used the rods and pistons that came with the block with a new set of bearings, rings, rod bolts, crank collar mod, oil pump gear mod and 1.2mm mls headgasket. Reused everything else that would have been on my 25 to finish build. So engine was exactly the same as what was in my rb25 except I now should have half a liter more displacement right?........... Wrong!!!! Car is up and running now and I have put a road tune on it and it feels no different from my rb25. As I stated earlier it feels just like my old rb25 and in some instances less responsive, was just being a bit stink with the less responsive statement, but I was expecting such a different drive that I meant every word of it. Same turbo on the car and the spool time is the same from a log I did full boost at 4000rpm flooring it in second, it doesn't light up the tires the way the 25 did. In fact it doesn't spin them nearly as much, don't get me wrong it pulls but just not as I imagined it. The off boost driving feels just the same as the 25. I figured spool time would drop at least 500rpm and I would need a new set of tires in a day or two from lighting them up in first second and third and off boost driving would feel like my old 25 driving off straight from cold start, but it doesn't. From the information I gave you what do you guys think? Am I just expecting to much or is my disappointment warranted? A little bit more information I forgot to mention. Car had oil leak around crank after fixing mistakenly put car timing out about a tooth drove round like that for about a week boosting and tuning noticed difference from taking longer to crank and loss of response. The car use to start basically half a crank but now it cranks longer to start ever since timing was out fixed it and since fixed the cranking hasn't improved and still feels a bit gutless on the power and response side of things.

Nobody knows if standard rb25det piston rings fit the standard rb30 pistons?

Hey there have another question for you guys can the rb30 piston rings interchange with the rb25 piston rings seeing as they are both the same bore?

Oh noo wasn't being cheap with pistons, just had a set of forged rb25det pistons already and wanted to know if they were usable. That way I could get a set of rods and have the best of both worlds. Thank you sir.

Some excellent information guys, thanks. One question that I cant seem to find the answer for that I have been wondering is what compression ratio would a set of rb25det piston get in a rb30 block that is not decked and running a 1.3mm headgasket? Also is it ok to run a 87mm headgasket with stock bore 86mm pistons?

Excellent cause that's exactly what I was leaning towards. Thank you for the quick and informative responses, I think that is exactly what I will do. Now do you have any suggestions on what piston and gasket combination to use to get a 9:1 compression ratio?

Hey forum I am back once again for the advice of the pros. I have not posted in awhile but been doing a lot of reading and topic watching, been a member for awhile and I must say this forum has helped me out tremendously. Had running a built rb25 in a 95 R33 with extensive mods for years and only recently cause of my negligence I have broken it. Sad sad day very sad , had an oil leak that i neglected and spun the rod bearing which messed up the crank and I said long ago if I ever had to go back into the engine it was rb30 or nothing. So guess what its rb30 time. I really only have one major question that I need advice on and it is as the topic says, what would be the better choice to go with if you ultimately had to make a choice between pistons or rods for a rb30 build? Car will be a daily driver and only looking for 400 to 500 wheel hp for now. If I decide to go any higher which will be awhile from now I will take it down and install the part/parts I need. I looked through all the threads and no real definitive answer thats why i decided to make a topic. Car is a 95 R33 gtst and I basically have everything I need for the install and with the budget I have opted to focus more on oil flow, oil return, block and head tidy up. For build I have sourced: N/A rb30 with oil and coolant holes already drilled Acl bearings main and rod 1.3mm MLS head gasket Reimax oil gears N1 oil pump N1 water pump Crank collar Head drain mod Vct external feed Valve stem seals Using hx40 turbo, meth injection, velocity stack intake mani, ss t4 twin scroll exhaust mani, 850cc injectors, walbro e85 400lph intank fuel pump, pfc, etc.... from cars previous setup. After all of this from what is left of the budget I have a choice to make between rods or pistons and do not know which to chose that's why I am calling on you to help me chose the better of the two that suits my build. All suggestions are welcome. I was thinking pistons as i can strengthen the rods up a little by replacing the rod bolts. What do you guys think?

OK thanks. Looking like it makes no sense to just buy the center piece, cause from what you posted it won't fit need all the other pieces as well. Shafts, specific bolts and flanges to hold the diff as it is made for the r32 housing which is smaller than the 33's. Dang was getting it on a hell of a deal to.

So with the half shafts is there a particular one for the r33 gtst or is it just a standard half shaft for the nismo lsd? Also will this require different bolts and stuff like that?

Hey forum just need a quick answer from someone with experience. I have the opportunity to buy a nismo 2 way lsd, just the center part. I would lime to know if it just bolts into the r33 gtst housing without modification?

Hey there thanks for the advice. I crossed referenced the lightning and z32 came up with a couple of numbers and got the car started. Hooray!!!!!!! Just needed that lil push to get it done. I have another question for you. My idle is a bit funny and I wanted to know if to correct that I need to adjust the voltage or load part of the curve? I tried the load part but it doesn't really seem to make a difference. If I were to adjust the voltage will that in turn make my max voltage less?

Yes I saw that but i am in need of more assistance. the trial version of nistune that I have downloaded only stays open for 5 mins or so and that is not enough time to compare all the maps i have to. I need more of a tutorial or for someone who has done it already to share the maps with me or walk me through how to re-scale mine. When I am in fc edit for example and at the maf settings table, the only number I should have to change would be the numbers that are associated with the maf that I am re-scaling right, this would be the chart located at the bottom of the page in fc edit?

Hey forum sorry to bring up an old thread but I am getting nowhere with trying to calibrate the ford lightning maf to work with my pfc. Is there anyone out there who can give me a tutorial, some info or numbers to put in the pfc to get me started? What numbers do I need to change cause I can not even get it started? If anyone has any idea and was wanting to try and cakibrate one of these meters on a pfc hit me up and let me know what to do/try. All/Any help is appreciated.

Hmmmmm. So the general consensus is that it will increase lag a bit, but with the potential to raise horsepower and lower discharge temps? Also another quick question can your exhaust pipe/muffler affect your turbo spool? A friend of mine had his exhaust system replaced from the turbo to the catback and now car has picked up lag? The first exhaust system he had was from the turbo all the way to the middle of the cat, one straight piece of pipe and the turbo spooled by 4400-4800 rpms, he now has a front pipe, dump pipe and decat pipe installed and that is the only change he made to the system and now he turbo spools by 5200-5600. That is about 1000rpm's worth of lag picked up and we can not figure why. System has been checked for boost leaks, there are none and also no exhaust leaks pre-turbo.. Like I said only thing changed was the exhaust system from the turbo to the cat back. So could that have caused the lag he now experiences?

Not really talking about extrude honing but more machining the area where the compressor blade fits and making that bigger. Would it increase lag and cfm or do absolutely nothing?

Hey forum I just have a quick question about a turbo's compressor housing. What would be the effect of a bigger compressor housing on a turbo? For example you have a 35r you take the compressor cover off and machine it out a little bigger and put it back on that same turbo what would be the effect on spool, cfm and horsepower? A friend of mine has a 35r he wants to sell me and he says the compressor housing was machined a little bigger. I just wanted to know if it is a worthwhile investment or if that mod just made the turbo worst?

Will be driven on the streets and daily but not really a street car. Really a drag fan and response on the street is not what I am after. Do not want a pig on the street, but full throttle all out power is what I am into can deal with full spool at 4000/4500 rpm with a redline of 8000. The street/autocross/track type race is not what I want. That setup you speak of does sound great but I only do 1/4 mile and more highway pulls on the street. Well the thing is were I am from there is no e85 or e70 as yet just 98 pump. Thats why I am on the methanol injection, plus don't you have to have the fuel system to support e85 or 70? Selling the built 25 end will be hassle as people over here have tendency to down play things and will want to purchase at little or nothing. Have read about some dsm guys making some serious hp on pump gas and meth injection.

Yea I know and I am pissed at myself for doing all these mods when I could have just saved and bought a rb30det one time. I really want 600rwhp. Knowledge really is power and a time saver, but at the time of these mods I was green and totally oblivious. That is spilled milk now and eventually I will get a 30 bottom end, but I just can't afford it at this time and will have to get there with what I have. Hopefully it will last long enough for me to save for the 30 bottom end or just lower my rwkw goal, which I really do not want to do cause I will still want around 500 to 550rwhp, but I know for the weight of the car I have being a R33 and the type of rwkw these guys have and low weight of their cars being evos, silvias, hondas and big hp supras that is the type of rwkw I will need to be competitive for the street import drag racing nights we have on Fridays.