Jump to content
SAU Community

Recommended Posts

Hi guys, I got my poncams installed today with 260 on the exhaust and 256 on the inlet with type-a valve springs.

I have a HKS GT2835 Pro S turbo, front mount, exhaust, all the other usual mods, injectors, fuel pump, Power FC etc. Before I got my cams installed I had a healthy 272 rwkw.

Today, with the cams installed I only got 258 rwkw!! Not only that, the boost came on later!

Now, the mechanic (I won't mention who it is) told me that before he was running 18 degrees of ignition timing, now it's running at 14.

Also, from the boost curve, he said that my boost controller, which is a turbo tech one, can't hold the new air flow the cams make, that's why there is a big drop in boost!

Frankly I am !ssed off as I spent $3,000 getting the cams and getting them installed, all to get less power with more lag, wtf!

Mechanic said I must have bad fuel in the car, because if he tried to run it at 18 degrees, he said it was pinging like crazy.

People, I need your help, and opinions as to what the F#%k is going on, and what I can do to fix it!

ALl the mechanic said was to use BP ultimate and get a apexi power fc boost controller next time for the tune and it should be fine, what do you guys think??!!!!!!

I attached the picture of the dyno before and after, please have a look and tell me what'sgoing on!

post-48356-1229073439_thumb.jpg

Link to comment
https://www.sau.com.au/forums/topic/248691-r33-skyline-gtst-turbo-cams-issues/
Share on other sites

I was under the impression that Tomei Pon Cams for hydraulic RB25's (R33) were 256 deg duration inlet and exhaust .

I had though the R34 versions were 252 and a tad more lift than the R33 hydraulic ones .

You may want to double check the boxes because there was recently a mix up between inlet and exhaust cams and almost R33 and R34 types .

No names but check all the part numbers .

A .

Sounds like a very similar problem i had man, but with my old HKS cams.

http://www.skylinesaustralia.com/forums/Di...+Valve++springs

No matter what we did we couldn't figure out what was going on. Ended up selling the cams, ripping the head off to check everything and now rebuilding the entire head with new cams.

What cam are you using on the exhaust side to get 260 degrees?

I was under the impression that Tomei Pon Cams for hydraulic RB25's (R33) were 256 deg duration inlet and exhaust .

I had though the R34 versions were 252 and a tad more lift than the R33 hydraulic ones .

You may want to double check the boxes because there was recently a mix up between inlet and exhaust cams and almost R33 and R34 types .

No names but check all the part numbers .

A .

THe inlet was a poncam 256, and exhaust was PROcam 260.

What you're saying that he could've put the 260 on the inlet side and 256 on the outet?

Nah that aint possible to do, the cam gears won't go on the wrong cams. But yeah running the procam on the exhaust side is a bit questionable. I thought the procams were only for solid lifters?

Check to see if they are on zero, all the cams I know of are already dialed in for a zero setting. Set them to zero and have a drive - you'll need a retune as well. I did the same thing with mine, and the tuner was more used to GTR tuning so wasn't aware that you set to zero for Gtst's. I went from 245rwkw without cams to 215rwkw with cams....bummer.

I reset them myself and the power difference was huge and very very pleasing. Got a tune later and 257rwkw.

You don't just set the cams to Zero degrees.

They NEED to be dialled in properly.

Also, running different sizes from inlet to exhaust does different things with the engine.

You will most definitely HAVE to dial them in to make the most of it, and this is why your power will be out and your ignition timing.

poncams on an rb will bring up your top end BUT will delay your boost threshold a few hundred rpm.

eg. my mate and i have the exact same setup, same tuner, same dyno... mine without cams, his with

i make 265rwkw with full boost by just under 3.5k

he makes 275 rwkw with full boost by just under 4k

Could bad fuel really cause the tuner to have to turn down the ignition timing from 18 to 14? (98 ron stuff).

Could the cams them selves be making the car ping?

I run BP Ultimate and my top end map is running between 12-14 ignition timing any more and it would detonate. I think you will find most PFC maps with skylines running decent boost will be very similar,I'm running 18psi with a 3037.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • If you are keeping the current calipers you need to keep the current disc as the spacing of the caliper determines the disc diameter. Have you trial fitted the GTS brakes fit on a GTSt hub or is this forward planning? There could be differences in caliper mount spacing, backing plate and even hub shape that could cause an issue.
    • Hi there I have a r33 gts with 4 stud small brakes, I'm going to convert to 5 stud but keep the small brakes, what size rotor would I need?
    • First up, I wouldn't use PID straight up for boost control. There's also other control techniques that can be implemented. And as I said, and you keep missing the point. It's not the ONE thing, it's the wrapping it up together with everything else in the one system that starts to unravel the problem. It's why there are people who can work in a certain field as a generalist, IE a IT person, and then there are specialists. IE, an SQL database specialist. Sure the IT person can build and run a database, and it'll work, however theyll likely never be as good as a specialist.   So, as said, it's not as simple as you're thinking. And yes, there's a limit to the number of everything's in MCUs, and they run out far to freaking fast when you're designing a complex system, which means you have to make compromises. Add to that, you'll have a limited team working on it, so fixing / tweaking some features means some features are a higher priority than others. Add to that, someone might fix a problem around a certain unrelated feature, and that change due to other complexities in the system design, can now cause a new, unforseen bug in something else.   The whole thing is, as said, sometimes split systems can work as good, and if not better. Plus when there's no need to spend $4k on an all in one solution, to meet the needs of a $200 system, maybe don't just spout off things others have said / you've read. There's a lot of misinformation on the internet, including in translated service manuals, and data sheets. Going and doing, so that you know, is better than stating something you read. Stating something that has been read, is about as useful as an engineering graduate, as all they know is what they've read. And trust me, nearly every engineering graduate is useless in the real world. And add to that, if you don't know this stuff, and just have an opinion, maybe accept what people with experience are telling you as information, and don't keep reciting the exact same thing over and over in response.
    • How complicated is PID boost control? To me it really doesn't seem that difficult. I'm not disputing the core assertion (specialization can be better than general purpose solutions), I'm just saying we're 30+ years removed from the days when transistor budgets were in the thousands and we had to hem and haw about whether there's enough ECC DRAM or enough clock cycles or the interrupt handler can respond fast enough to handle another task. I really struggle to see how a Greddy Profec or an HKS EVC7 or whatever else is somehow a far superior solution to what you get in a Haltech Nexus/Elite ECU. I don't see OEMs spending time on dedicated boost control modules in any car I've ever touched. Is there value to separating out a motor controller or engine controller vs an infotainment module? Of course, those are two completely different tasks with highly divergent requirements. The reason why I cite data sheets, service manuals, etc is because as you have clearly suggested I don't know what I'm doing, can't learn how to do anything correctly, and have never actually done anything myself. So when I do offer advice to people I like to use sources that are not just based off of taking my word for it and can be independently verified by others so it's not just my misinterpretation of a primary source.
    • That's awesome, well done! Love all these older Datsun / Nissans so rare now
×
×
  • Create New...