Jump to content
SAU Community

Which Camshafts?

Jamtime

By Jamtime,
in Engines & Forced Induction

 Share

Recommended Posts

TiTAN Grand Master

TiTAN

Posted
Posted
A worked motor with fuel economy and low down drivability, I would like to see that.

RB30 twin cam with 9.2-9.4:1 compression and a GT35 on the side of it, happily plods around in traffic at 1500rpm and gives ~12l/100km city driving

low gown driveability and response are the things to cling to for satisfaction when a combo just doesn't cut the numbers. :cool:

thats why we have twin cam forklift engines because you can have your response and 400kw :P

  • Replies 56
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Posted Images

Fastrotor Proficient

Fastrotor

Posted
Posted

Hmm interesting topic for sure.

Since head porting is a major part in making big cams work, i think this should be ok to ask in this thread.

I was doing an excel spreadsheet of all the different rb26 head flow numbers i could get my hands on. Some were better than others in the mid range, some a bit better in the top end, to be expected , with differences in machine measurements and job expectations (we don't know they were all for a 'max' flow job etc. Anyhow point is, they were pretty close to each other with nothing HUGE standing out...... EXCEPT ......

Endyne......... and only the exhaust ports..... they were on top in the intake too but only by a small amount. On the exhaust flow results, most topped out at 190 odd cfm ................. there's was around 230+ cfm !!!!!!!!!

Im peeved i seem to have deleted the xlsx spreadsheet else i would post. I guess i could redraw it if anyone was keen to see.

So i'd like to hear from the guru's what they think.

Paul, you being the RS guru, do you have flow numbers for your head please ?

NickR33 Grand Master

NickR33

Posted
Posted

its my understanding that lift and duration have different effects too... duration refers to where in the rev range they are most efficient and increased lift means more airflow at that rpm (which usually means more power)

I've got 260º 10.8mm cams but engine builder reckons he would just go back to standard cams for my car, no real gain to be had in his opinion... but I like the sound lol

livicuru Proficient

livicuru

Posted
Posted
im sorry but yours sounds like one of the worst setups i've ever heard of on a rb

You reckon? well according to my tuner my high mounts with the slighty down sized rear housing come on boost the same time as Rs's but only much harder. Anyway, you have no idea about the overall setup i have and how it compliments the remainding engine mods, hence your narrow statement.

All the best Jam; dont sell your Rs's. :P

JAGR33 Grand Master

JAGR33

Posted
Posted
Lol :) I completley agree with you there. but isnt this guy building a street car...id be willing to sacrifice some top end in a street car for better (in theory) fuel economy and low down drivability.

Hit the nail on the head!!!

Interesting thread, guaranteed to get people fired up!!

I did run 260/9.15 lift poncams with -5's on a built motor, but reverted back to standard cams under instructions from my tuner/mechanic.

One major difference I noticed was pulling into my driveway at home and driving up into the garage (very slight incline). With Poncams my car used to be lethargic. Travelling 10km/h up the driveway my car felt like it needed revs to get into the garage. Once the standard cams were put back in the car it would pretty much idle up the driveway into my garage without a sweat. Now what does this mean? Maybe someone with more technical knowledge than me can explain...

I also felt my on/off boost transition more responsive aswell.

The car made just as much power and similar response (maybe slightly favourable with standard cams) to the Poncams..

Just my 2c.... :O

N1GTR Grand Master

N1GTR

Posted
Posted

Step Zero;

Suits Stock turbos or GTSS, 8000rpm.

Quite a rare crank though, id be suprised if there was many more step zero's than kakimoto's or apexi highdecks.

Anyway, here's a PDF from HKS about this kit:

HKS_Step_Zero.pdf

djr81 Grand Master

djr81

Posted
Posted
Hit the nail on the head!!!

Interesting thread, guaranteed to get people fired up!!

I did run 260/9.15 lift poncams with -5's on a built motor, but reverted back to standard cams under instructions from my tuner/mechanic.

One major difference I noticed was pulling into my driveway at home and driving up into the garage (very slight incline). With Poncams my car used to be lethargic. Travelling 10km/h up the driveway my car felt like it needed revs to get into the garage. Once the standard cams were put back in the car it would pretty much idle up the driveway into my garage without a sweat. Now what does this mean? Maybe someone with more technical knowledge than me can explain...

I also felt my on/off boost transition more responsive aswell.

The car made just as much power and similar response (maybe slightly favourable with standard cams) to the Poncams..

Just my 2c.... :)

It means that longer duration cams work less well at low rpm.

Here is a rough chart showing the durations of stock versus Poncams. Pretty obvious but I don't know what the lift is on the stock cams.

post-5134-1264052933_thumb.jpg

bigslick Collaborator

bigslick

Posted
Posted
All the best Jam; dont sell your Rs's. :blush:

I wish you all the best with your setup too, Jamtime, but your step 0 kit is going to be significantly outpowered by the GT-RS's.

Even the crank in the step 1 wouldn't be able to use them to their potential.

Personally I think -5's make a great street turbo, with a 2.8 stroker even better, but not that one.

R.3.2.G.T.R Grand Master

R.3.2.G.T.R

Posted
Posted (edited)

great thread, been reading other poncam discussions however nothing similar to my setup, rb26 with gt-ss with no headwork but with cam gears, I read -5 guys using the popular 260 9.15mm combo (type b) but not a lot of info with gt-ss

What bout tomei type a which is staggered setup?? Must be of some benefit for smaller turbos.. Type B surely isn't more suitable as it will move the powerband higher.. Is stock cams still best with gt-ss?? Btw car is street driven as a daily

Type A

Duration(IN)- 260°

Duration(EX) - 252°

lift(IN) - 9.15

lift(EX) - 9.15

Type B

Duration(IN) - 260°

Duration(EX) - 260°

lift(IN) - 9.15

lift(EX) - 9.15

Edited by BWRGTR
djr81 Grand Master

djr81

Posted
Posted
great thread, been reading other poncam discussions however nothing similar to my setup, rb26 with gt-ss with no headwork but with cam gears, I read -5 guys using the popular 260 9.15mm combo (type b) but not a lot of info with gt-ss

What bout tomei type a which is staggered setup?? Must be of some benefit for smaller turbos.. Type B surely isn't more suitable as it will move the powerband higher.. Is stock cams still best with gt-ss?? Btw car is street driven as a daily

Type A

Duration(IN)- 260°

Duration(EX) - 252°

lift(IN) - 9.15

lift(EX) - 9.15

Type B

Duration(IN) - 260°

Duration(EX) - 260°

lift(IN) - 9.15

lift(EX) - 9.15

A -5/Poncam B combination will put your maximum torque at 5000rpm or higher depending on what boost you run.

The inlet cam on the type A & B is the same cam.

The exhaust cam on the type A is, in duration, very little different to the stock cam, just with higher lift & very slightly less advance.

Curiously I have seen very few people running -5's with the type A's. I really cannot find a good reason not to use this in place of teh type B's.

Also Tomei will sell you inlet cams with a 252, 256, 260, 270, 280 etc etc durations. You can mix & match & don't have to select a type A or a type B set up.

djr81 Grand Master

djr81

Posted
Posted
LOL, they sure dont feel like it to drive

Should feel like a turbo diesel compared to RB20 powah. :domokun:

At the end of the day it is a turbo motor & when you start running anything like a sniff of boost (1 bar or better) the peak torque is going to move up the rev range. The issue is, I guess, how to make good torque in the midrange (say 4000rpm) without it dieing in the arse up the top end.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
    • perry_r33
      R34 GTR Vspec Garage Sale - All must go!

      By perry_r33 · Posted

      Pm sent 
    • Robot
      Skyline v36 350GT sedan hunting on idle

      By Robot · Posted

      Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • GabsReDeal
      R32 GTS (RB20DE) Injectors Replacement

      By GabsReDeal · Posted

      After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
×
×
  • Create New...