R33 Rb30 Conversion

[Cubes]

That's ~24.5 kph per 1,000 rpm, are these dyno runs done in 3rd gear?

With barely 35 lbs on the seat when new and 1 bar of boost, I have no doubt that the valve springs are "playing up".

cheers

The dyno runs are done in 4th, the car ran 18" wheels 235's I forget the profile.

Regarding the valve springs.. Dialing in 18-19psi the lifters would pump up and the power curve drop off sharply. Quite scary. :S

[ISL33P]

so you would not recommend any of those plenums to a customer ? be it rb20/25/26.

all flow testing, for the time being, is currently being carried out by a local engine builder on a sf600 flow bench, so i cant see how he would do it incorrectly. all these figures arer on invoices if you like to see them. totally unbiased as i am not there when it is being done and he does not have any involvement in the development of my products.

the flow of each port is measured while every other port is blocked off with only air being drawn through the throttle body to give the best possible indication of the amount of air each cylinder is receiving. although it does not take into account what is happening in the other cylinders it gives the most consistent reading for each port without any other having an effect.

from what i have done, variances like these do not have a real effect on engine performance until the envelope s really being pushed with leaner than usual afr's and big amounts of airflow. at the afr's more commonly associated with street cars, around the 11.5:1 mark, this does not casue a problem as it is being tuned to compensate for the highest flowing cylinder/s (3 & 4) and to not cause a lean out.

every car i have seen after being tuned has variances in the colour of the plug which would support the flow figures i have. most recently seen a car lose compression in 3 & 4 when tuned at 12.5:1......this is no coincidence, just the practical proof of what the flow bench shows.

what figures flow do you have ?

ps - please pm those egt's as they didn't turn up last time

[R32 TT]

the flow of each port is measured while every other port is blocked off with only air being drawn through the throttle body to give the best possible indication of the amount of air each cylinder is receiving.

I am not an expert, but wouldn't blocking all other ports off completely change the dynamics of the particular port you are testing? For example if you are testing port 3 and had ports 4,5 and 6 open as well, then would there be considerable air velocity rushing past port 3 to get to the later ports. And wouldn't this have a vacuum effect at port 3 - almost a scavenging effect from its potential flow?

If air takes path of least resistance, then if port 6 is 'easy' and open, other ports will flow less, even though on an individual basis they all flow the same?

[ISL33P]

the path of least resitance would be that where the air can escape the easiest, being the only cylinder which is not blocked and being tested.

all in all its is quite hard to replicate the combustion process and the effects on airflow in an intake manifold/plenum on a flow bench and this seems to give the best results when compared to the performance of each cylinder.

having said all that it would be interesting to test the plenum with none of the cylinders blocked or have them blocked in pairs replicating when they are at tdc.

you would be surprised to know that 6 always flows the least in all rb series intake manifolds/plenums.

[Sydneykid]

you would be surprised to know that 6 always flows the least in all rb series intake manifolds/plenums.

Except when you bolt an RB26 plenum/inlet manifold onto an engine, add some boost and #6 then flows the most. The aerodynamic experts tell me that's because the pressure backs up at the rear of the plenum. Can't duplicate that on a flow bench, wish I could.

The RB25DET EGT results from testing in 2003, R33GTST with 263 rwkw.

RB25DET Standard inlet plenum

Average of 3 runs, with 5 minutes between runs

Ambient temperature 28 degress

A/F ratio 12.0 to 1

3,000 4,000 5,000 6,000

rpm rpm rpm rpm

#1 580 645 732 802

#2 582 647 732 805

#3 581 648 734 806

#4 580 647 732 805

#5 582 649 735 812

#6 582 650 739 815

Note the higher temperatures at #6 and to a lesser extent #5. We put that down to water circulation differences.

Same engine, same dyno, same pyrometer, testing done the following day after plenum swap;

RB25DET Greddy inlet plenum

Average of 3 runs, with 5 minutes between runs

Ambient temperature 27 degress

A/F ratio 12.0 to 1

3,000 4,000 5,000 6,000

rpm rpm rpm rpm

#1 580 643 732 803

#2 582 642 731 805

#3 581 648 732 806

#4 586 647 734 808

#5 582 650 739 818

#6 582 655 745 824

Note the higher temps at #6 and #5, some of which could be attributed to the water circulation as per the standard plenum. But the differences are noticeably higher than what could be attributed to that, hence the conclusion was that it was due to flow differences in the plenum/inlet manifold causing leaner A/F ratios and even higher EGT's.

I have about 5 more sets somewhere, one was for the RB26 standard plenum, I will try and dig it up.

Draw you own conclusions, the absolute numbers will vary from engine to engine of course, but the differences are what's important.

cheers

PS; digging this up last night has prompted me to do similar testing on the RB31DET, which I will post up when it is dynoed.

[Spoolup]

Hi Ariel,

How much less does no#6 flow on your plenums.

My engine gets dynoed next Tues so Ill keep you posted on results.

Cheers

the path of least resitance would be that where the air can escape the easiest, being the only cylinder which is not blocked and being tested.

all in all its is quite hard to replicate the combustion process and the effects on airflow in an intake manifold/plenum on a flow bench and this seems to give the best results when compared to the performance of each cylinder.

having said all that it would be interesting to test the plenum with none of the cylinders blocked or have them blocked in pairs replicating when they are at tdc.

you would be surprised to know that 6 always flows the least in all rb series intake manifolds/plenums.

[shanef]

would the RB30 bottom end with a 26 head affect the flow characteristics of the plenum? being lower revs and more capacity?

[Cubes]

Well this has turned in to quite a functional 'discussion'.

[R32 TT]

Well this has turned in to quite a functional 'discussion'.

...touch some wood.. do it now before its too late!

[Guilt-Toy]

how did the plasmaman go sydneykid ?

[ISL33P]

was that testing done using a standard computer or a computer that can control individual injector duty ?

Spoolup - Brad nowhere near that of the standard plenum

Cubes - that's what its all about

[Adriano]

5 & 6 flow better than the others, as more air makes it run leaner, hence higher egt's, on the power fc, i add 1% to #5 and 1.5% to #6 on a gtr

[fatz]

when you get your incjectors cleaned i though everyone puts the one with slightly more flow in the rear cylinders

i know i do

[nemini90]

hey guys just wanted to know what piston to deck hight mesurment you had im using a cp-rb30/rb26-020-9.0 piston and rb25det head and have a mesurment of 1.75mm and am using a 1.2mm head gasket dose this seam right to you

[kaige]

Hey guys, I'm just about to bolt my rb30 / 25 together and the only thing left for me to buy is the timming belt.

I've decided to use the existing hole in the rb30e block and add a second tensioner because the block im using is all in one peice and i dont want to go drilling anything.

Pic:

http://www.users.bigpond.com/allanreynolds...timingbelt2.jpg

Just want to check before I go down this road if anyone has had any problems taking this option and if the size of the timing belt this guy recomends fits ok.

Timing belt details are - Gates POWERGRIP GT2 p/n 1200 8MGT 30

it measures 1200mm long, 8mm pitch on teeth, 150 teeth, and 25mm wide but it was cut down from 30mm in the factory! Cost $80 as it's a heavier belt.

Any comments or help would be really helpfull!

[Bl4cK32]

thats a dodgy method compared to the other way. Drilling the hole above the w pump is better and no big deal. Its safer as well...see how damn close the belt is to the other side....

[r33_racer]

drill slow and with lots of grease to catch the filings...and same with tapping the hole. or if the head isnt on yet...get a vacuum cleaner sucking from the water gallery that your going to drill into and hopefully pick up all the filings.

[Sydneykid]

was that testing done using a standard computer or a computer that can control individual injector duty ?

It was a Power FC, so we can (and did) richen up #5 and #6 after these runs to even up the EGT's. After all that's why we were testing the EGT's in the first place. It wasn't to put shit on the plenum/inlet, it was done to ensue that the individual cylinder tune was as good as we could get it.

Keep in mind that #6 already had the highest flowing injector (+1.0%), then #5 (+0.8%).

We only had 2 F&W lamba sensors back then, so EGT was the best way to balance the 6 cylinders. Now we have 4 sensors, so we can do a 6 cylinder with 2 power runs on the dyno, by swapping 2 injectors around. We do one run and log 1,2,3 & 4 then the next run we log 3, 4, 5 & 6. Then we line up 3 and 4 for the 2 runs and that tells us if we have any issues between 1 & 2 and 5 & 6. The pyrometer readings were pretty good for balancing A/F ratios, but the lambdas are better.

cheers

[VHR32]

I had a quiet day at work today so did a bit of emailing and ringing around to find out about pistons....

CP Quantum Racing Industries

All compression ratios are based on zero deck height, 1.2mm head gasket (7.13cc), RB25 @ 62.5cc, RB26 @ 64.5cc. They assure me they have done alot of work to make sure the facts are correct.

p/n= CP-RB30/26-.20

Flat top with no valve pockets

8.2:1 compression with RB25 head and bit less with RB26 head

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize but can be custom ordered in any size.

p/n= CP-RB30/26-.20-9.0

6.0cc dome top,

9.0:1 compression with RB25 head and bit less with RB26 head

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize but can be custom ordered in any size.

*Care must be taken when using on RB26 with more than 11.5mm valve lift*

ARIAS Rocket Industries.

Suit RB30/25

p/n= AP332105

13cc dome top

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize (86.5mm).

Using http://www.csgnetwork.com/compcalc.html and the combustion chamber measurements taken by QRI as above

86.5 bore, 85mm stroke, 87mm x 1.2mm HG, 62.5cc chamber, 13cc dome = 9.46:1 compression ???

Suit RB30/26

p/n= AP332104

10.6cc dome top

21mm pin

1.280" compression height

Only stocked in 0.20 thou oversize (86.5mm).

86.5 bore, 85mm stroke, 87mm x 1.2mm HG, 64.5cc chamber, 10.6cc dome = 8.88:1 compression ???

WISECO

Skyline RB30 w/ DOHC RB25det cylinder head

1.260" compresion height, 66.5cc head chamber, Dish top -11.3cc, 7.0:1 compression ratio, 21mm pin, 1mm gasket thickness, 1mm deck clearance.

K577M865 86.5mm

K577M87 87.00mm

ACL

6MKRY9608 (VL turbo)

87mm, -4.5cc dished top, 1.261" compression height, 21mm pin,

Standard RB30ET pistons are 7.8:1, with RB25 head it is 7.1:1

These are meant to be bumped up to 8.5:1 in a RB30ET, so with the RB25 head it may give about 7.8:1??

Updated.

So CP have have 6cc dome = 9.0:1

Arias have a 13cc = 9.4 approx? and 10.6cc = 9.1 approx?

Not sure what Arias quote the compression ratio to be but something doesn't seem right with all these figures. I know they arent accurate but its a guide.

Has anyone worked out c/r with Arias pistons???

Edited November 28, 2006 by VHR32

[kaige]

drill slow and with lots of grease to catch the filings...and same with tapping the hole. or if the head isnt on yet...get a vacuum cleaner sucking from the water gallery that your going to drill into and hopefully pick up all the filings.

Yeah i see what you are saying, but if this method works and is safe i still cant see why not to do it this way...

Timing belts move bugger all as it is but i thought with two tensioners it would be ok.

has anyone heard of the belts clashing before?

Just dont want to do drill and tap holes into a perfactly good motor.