Jump to content
SAU Community

Recommended Posts

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

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 ?

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

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

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

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

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

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.

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
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.

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



  • Similar Content

  • Latest Posts

    • The 296mm rotors are the R33 turbo brakes. The 310mm rotors are the R34 turbo brakes. The calipers are nearly the same, but not. They're the same caliper but the R34 caliper has longer legs so that it sits out far enough to go over the rotor. The pads are the same for both. When you say, "I bough tsome EBC"....did you just mean pads? Or rotors? 310mm rotors fit under 17" wheels. There may be some wheels without enough clearance though. I can't fit my fingers between the barrel of my wheel and the "corners" of my R34 calipers, but there is plenty of room behind the spokes. This is on Enkei RPF1. You can fit 324mm rotors inside a 17" wheel, but I'd be willing to bet that it would be close to impossible with the Nissan/Sumitomo caliper (using an adapter, of course), because the Sumitomo caliper is fatter than the Brembo caliper that is supposed to go on the 324mm rotors.
    • Hi. Can someone tell me what brakes(and mainly WHERE) can i buy brakes on R34 GTT? I bought some EBC which SHOULD go on my car(i have GT but it has GTT brakes) but it does not fit, Brakes are "too" small(296mm) Are 310mm be good or? I have 17 inch wheel so no "big boys" but for me driving i just need one that fits and i can get here in EU/Czech.
    • Since winter isn't that harsh anymore in Poland, i will definetely drive it 365 days a year 😉. But if the snow hits i will try it for sure and let U know. Only swap i am planning to do is of course R34 GTR front 😍.
    • Hey. Very valuable information about pitwork, I will pay attention when buying any consumable parts 🙏 As for the carpets - I got a handful of information from nengun, from which it appears that indeed the carpets for the driver's side are OEM. They are not able to show me any pictures due to the long chain of different sales entities but after I place the order, as soon as the goods arrive at the nengun warehouse from which they will send the shipment to me they can send me photos and if my purchase differs from OEM I can immediately return it / cancel the purchase. I think I will give it a try 😉. Of course i'll let you know what's what as soon as i get them P.s. I know the topic is not relevant to the thread, but both nengun and amayama have these SICK 😍 trunk room lamps available. Do you know anyone who ordered them? I need to have one in my car
    • I've managed to find this: Nissan_Stagea_AutechVersion260RS (1).pdf
×
×
  • Create New...