Got Over 400kw Atw?

[Ryan1200]

I am assuming you're using standard manifolds Ryan?

Great result!

Actually stock manifolds that I got UAS to get extrude honed back 2004 been 100% reliable so far. The exits of the manifolds were slightly larger than normal definately alot smaller than the gasket size which it is now. Got e85 and toluene/pump testing to go so will see how far we can keep pushing the low mounts.

[R31Nismoid]

Well 2530's have done 450rwkw before on fuel other than 98 (as you have also), so you should be around that, doesn't look to be too far off either.

[mico]

Goes to show it's worth port matching the stock manifolds to the turbos, and here I was laughed at in a recent thread when I mentioned doing it in 350kw+ applications.

yeah thats right mate !!! well done ryan i have seen your car at willowbank its ridiculous !!!

[rob82]

Closer inspection was almost identical boost pressure but only 395kw on this particular run. I ran 131mph on 395kw so will see in a few weeks if it turns in mph.. Changes that could account for the gains were opening up stock manifolds and port matching everything. Removing unused 02 sensors from the very small split dump entries. Repairing front turbo outlet pipe which was squashed after i got to it with a hammer to make some clearance from the rocker cover due to a miss allignment of the front compressor housing and i CBF pulling the turbo off.. So bring on willowbank i can finally start working on getting my times down without getting asked to leave every visit..

That's a very dubious result - I'm very skeptical that there would be gains throughout the entire rev range. Making things flow better usually decreases hp at low velocities and increases hp at higher velocities. My bet it was a different shootout mode or strapping technique or some kind of dyno technique.

[Marko R1]

There are good gains to be had by porting. In terms of percentage, Ryan's car gained 5% which sounds very real to me.

[rob82]

There are good gains to be had by porting. In terms of percentage, Ryan's car gained 5% which sounds very real to me.

I'm not saying there isn't gains to be had from porting but ryans's car has increased volumetric effciency throughout the entire rev range. I've never witnessed this on any port job I've seen, there are always trade offs.

Edited March 23, 2012 by rob82

[Ryan1200]

I'm not saying there isn't gains to be had from porting but ryans's car has increased volumetric effciency throughout the entire rev range. I've never witnessed this on any port job I've seen, there are always trade offs.

Shootout 6f and strapped down as per normal and wasn't leaving the rear roller but regardless all the little improvements should've help so the strip should show something..

[bigmikespec]

I'm not saying there isn't gains to be had from porting but ryans's car has increased volumetric effciency throughout the entire rev range. I've never witnessed this on any port job I've seen, there are always trade offs.

Very simple, he has decreased exhaust manifold back pressure.

[rob82]

Shootout 6f and strapped down as per normal and wasn't leaving the rear roller but regardless all the little improvements should've help so the strip should show something..

Was it run in on a 2wd dyno or 4wd. I fully understand how difficult it is to get reliable data even at lower horsepower levels I've been tuning cars for years now and there is a lot of work to get reliable dyno readings - to me that's what makes a good dyno operator. It's an art in itself.

That aside results like this have got to make you wonder if the dyno techniques were consistent for the two runs. Anyways the mph should tell the story because if the dyno results are indicative of the power gain then your probably looking at another 3-5mph gain.

It's funny that there is one thread with tubular manifold that look to have been quiet well designed that shows no gain in hp power and then there is this thread which says the opposite.

[rob82]

Very simple, he has decreased exhaust manifold back pressure.

In this situation nothing has change on the intake side and the boost pressure is the same before and after. That means exhaust back pressure is only a function of flow through the turbine. As the flow through the turbine increases with rpm the back pressure increase exponentially meaning that if you port the manifold and make it flow better the gains will only be noticeable at high higher rpm. The other thing I havnt mentioned is the effect of gas velocity on turbine efficiency.

[Rolls]

If you decrease backpressure you can increase scavenging hence VE, it is like putting a cork in the exhaust, it will kill power everywhere but especially at high rpm, doesn't make sense for it to gain linearly over the entire power band.

[bigmikespec]

In this situation nothing has change on the intake side and the boost pressure is the same before and after. That means exhaust back pressure is only a function of flow through the turbine. As the flow through the turbine increases with rpm the back pressure increase exponentially meaning that if you port the manifold and make it flow better the gains will only be noticeable at high higher rpm. The other thing I havnt mentioned is the effect of gas velocity on turbine efficiency.

I do not see why you find it so difficult to comprehend. Look at the graph, as it is starting to make power (as boost pressure is increasing) it is making more power than before as a result of less manifold back pressure that allows the engine to breathe better and behave like an N/A engine. Flow through the turbine was impeded by the exahust manifold, simple. It disproves your higher rpm only theory.

[rob82]

I do not see why you find it so difficult to comprehend. Look at the graph, as it is starting to make power (as boost pressure is increasing) it is making more power than before as a result of less manifold back pressure that allows the engine to breathe better and behave like an N/A engine. Flow through the turbine was impeded by the exahust manifold, simple. It disproves your higher rpm only theory.

If you've ever plotted exhaust back pressure vs intake pressure you would see what I mean. Exhaust back pressure isn't directly related to intake pressure.

And if you slightly restrict your exhaust system the losses will only be above the rpm where the growth in exhaust back pressure starts to become substantial NOT throughout the entire rpm range.

[black bnr32]

Decided it was time i did some proper port matching on the twins and open up the exits of the manifold while i was there. Looks like it payed off i went from 405rwkw to 430 on 1 psi less boost using 98octane at 23psi. Check out how flat my boost curve is.

full boost at 4400rpm-ish?

[GASCO123]

GTR R34 RB30 conversion

RB30 block rebuild by Pro engines, inc forged pistons, rods.

Nitto oil pump

Garret -5 new turbos

Aftermarket injtrs,manifolds, cams, detail not known

Reconditioned GTR head

Drives like a V8

On boost above 2500 rpm, smooth as, with progressive boost increase.

Torque tapers off above 5500 rpm, but still 77% max torque at 7000rpm

Interesting to compare this with Racepace Ben's WOW 2.9

Low rpm torque better than Ben's up to 5000 rpm, then Ben's better revability takes over.

Worth mentioning this dyno done on 4WD. Ben's on 2WD. 4% difference maybe?

Also note, Ben's diff is very short, 230 kph at 8000rpm

With RB30 bottom end, rpm limited to 7200.

Max torque at 3500rpm and comes up nicely from 2500 rpm.

Estimated air flow 32 lb/min at 21 psi each turbo. Equates to about 10.5 FWHP per lb/min air.

[Ryan1200]

full boost at 4400rpm-ish?

Yep close about 4300 on pump but I think around 3800 on e85. I still believe my +2mm Exhuast valves effect spool a bit... Not only was it a smallish outlet on the manifolds but there could have been a nasty square edge in the mix aswell I really should've matched it up earlier but got lazy...

[Piggaz]

^^

Your big valves helping or hurting?

Are you using pods or an air box?

[bigmikespec]

If you've ever plotted exhaust back pressure vs intake pressure you would see what I mean. Exhaust back pressure isn't directly related to intake pressure.

And if you slightly restrict your exhaust system the losses will only be above the rpm where the growth in exhaust back pressure starts to become substantial NOT throughout the entire rpm range.

I am not suggesting anything like that.

Without measuring it is wrong to assume, the exhaust manifold in this case may have been a restriction from 4000rpm onwards.

[bigmikespec]

^^^did someone say "better revability"... oh man!

[R31Nismoid]

Also note, Ben's diff is very short, 230 kph at 8000rpm

How do you work that out exactly?

You - 175km/h @ 7000rpm (4th)

RPMGTR - 230km/h @ 8000rpm (4th)

You are doing 150km/h @ 6k, 175km/h @ 7k... So roughly 200km/h you are 8k

Meaning yours is the shorter ratio... So of course yours appears more responsive.