My 300rwkw Adventures

[Dale FZ1]

Looks like it's nearly time to start a split pulse thread to keep this one on-track.

The WRC rally rockets use split pulse designs in their restrictor-equipped engines which are basically strangled for mass-flow up high and therefore have a fairly narrow useable rev range. Those things punch hard down low in an un-Godly manner, and the setup works. BUT they are also designed / intended to run at full throttle / load as much as possible AND have 4wd to put the grunt down.

I agree with Cubes in that the most appropriate road-spec Skyline is the one that gives the ability to respond in lower gears without simply frying the rubber because of the quantity and delivery of torque. Put simply, it's got to be USEABLE as Adrian indicated with half and three-quarter throttle delivery probably more important for general road use. The ability to transition from light to full load torque with power-down to the road has got to be the smart way.

If Mafia had the option of a split pulse housing, with A/R options (important as Cubes said) then he'd have been mad to not go that way - price dependent of course. Useless dreaming though, because there are only so many options, and only one split pulse housing size.

Back onto the main thread.

Mafia's been off line for a little while so until he's back who reckons they could justify/use 300rwkW? I've never experienced that on 4 wheels, but have had about twice the power:weight with my bike - and LOVED it.

[BHDave]

Mafia's been off line for a little while so until he's back who reckons they could justify/use 300rwkW? I've never experienced that on 4 wheels, but have had about twice the power:weight with my bike - and LOVED it.

Them's fightin' words!

It's a pretty subjective question, which will probably result in a lot of people arguing. Personally, i'd say it can be justified, but only if you have the rest of the car set up in such a way that it can utilize that sort of power without breaking into wheel spin at the first hint of boost.

[Dale FZ1]

Them's fightin' words!

Personally, i'd say it can be justified, but only if you have the rest of the car set up in such a way that it can utilize that sort of power without breaking into wheel spin at the first hint of boost.

Don't take me too seriously Dave, I will happily confess that I don't belong to the 300rwkW club in terms of driving ability. That was something I had to come to terms with in deciding the development path for self and car.

So... chassis development?

How does yours put the power down, and what did you do (if anything) to make it better?

[BHDave]

Day's winding down so have some time to bang on now.

I haven't done anything spectacular with mine, I think it generally maintains traction due to the fairly linear power delivery, combined with decent rubber and the rear wheels sitting up pretty straight (less than -1 degree camber). The mechanical diff made the biggest difference though, after it was installed the car would just maintain traction (in a straight line) all the time, where previously you'd regularly get the instant 1 wheel spin and snap sideways in 1st, 2nd and sometimes 3rd. Even on corner exit, if it breaks, it's easily controlled and can be brought back in with no issue.

All the bushes are replaced so there's no slop there, alloy subframe collars installed, sway bars done, adjustable upper arms rear as my car is too low to get away with adjustable bushes, and cusco coilovers (which is a bit on the stiff side and a bit under damped truth be told), hicas locked. Thats it.

atm it has rt215's on the back 235 wide, prior to that it had a set of shagged d01j's (i think) 225 wide. They were noisey bastards.

[Dale FZ1]

I'd have to say that in my case the rear suspension settings have made small but noticeable traction improvements.

So the mechanical diff made the big difference? What spec are you running?

Edited May 21, 2007 by Dale FZ1

[BHDave]

Nismo 1.5 way (not a pro) It's a bit tighter than i'd like really, but it's still pretty new so it might soften up a bit with a few more km's

[tridentt150v]

The good thing about a mech. diff is that if you do happen to loose traction, it drives straight cos both wheels load up. This makes the car so much more predictable and controlled.

[The Mafia]

Hi everyone, sorry about the slack replies again, been out of town, and sick all at once.. Heh, I'll gt over it. Nice little discussion here (well done to dale, BHdave, Disco, Cubes, etc), I'll try and answer most of your questions.

Mafia can you tell us whether you’ve looked at the inlet manifolding as a hurdle? And you still haven’t told us what the car is being used for.

Hey dale, I've had a look at the inlet manifold and are now wondering where I would put the WMI nozzle if I Was to put on one of those cast Greddy copies. Cubes has also notified me in a PM that I need a bigger intake chamber if I was to move to the 3.0l bottom end. THis is interesting - and if anyone could elaborate on this particular point I'd be interested in what they have to say.

Cubes, maybe the RB20 intake is smaller that the RB25?

AS for the cars purpose - I'm using it for around town driving, travelling, and draging. I managed 10l to the 100kms on my last trip which isn't bad considering I was flogging it a fair bit of the way, passing cars at full throttle (which is so much fun) and yeah sitting on 120kmph (thats 3100rpm!)

Just wondering after al this, is my HKS rb26 ex manifold suitable for this sort of aplit pulse scavenging setup, as the runners arent the same lenghs?Another question Mafia, when you were tuning this, if you added more timing did it ping, or did it just lose power, all the rb's ive tuned ive found max torque for a given load is found just shy of detonation, which is the opposite of other motors ive tuned, whereby max torque is found well before detonation.

well, it was weird it would ping randomly (my guess the .63 housing was at its limits) but I could advance the timing to a point where it was not doing anything. I took 3 degrees out and it lost 5 rwkw. So not really worth having it there IMO. I want to start aiming for faultless driving (ie no ping at all) so I might have to make a few changes to the tune. I don't mind running WMI 24\7 because it uses bugger all water anyway (probably 2 litres of WM every 2 tanks of fuel). I fill my washer bottle up more often now.

Disco, I'm somewhat skeptical of the twin scroll turbos. They sound great on paper but the dynos that have been posted over at FA have been less than stellar. Have you got any hard proof that the twin scroll is worth the extra effort and more importantly, the extra money?

I am too - I've seen a few dyno plots, and even though they manage to give about 10% - 15% more midrange, I still cannot justify the cost. I'm running 300rwkw here, off a standard manifold, and standard type exhaust housing. If I were to change to a split pulse design:

1. Exhaust manifold - $1000

2. External Gate - $800

3. Gaskets - $100

4. Rear housing - $600

5. New Dump and fabrication - $800

Total: $3300

I could rebuild the engine with a 3l bottom end for that much. And I can also give the guarantee that the 3.0l bottom end is going to give you a heap more bottom end that a twin scroll housing, and with better fuel economy. (Twin scroll needs to be on boost to provide that bottom end)

I'm not knocking your split pulse idea Disco, but some times I just cannot see how it would be financially viable when you could go for the much better option with the RB30? Even if the RB30 cost a little more, its going to yeild much better results. I am sure you could get a 3.0l bottom end done by someone for around the 4k mark. I'm getting it done for about 2k, because I know way too many people, and the engine is being built in my garage.

Looks like it's nearly time to start a split pulse thread to keep this one on-track.

Thats a good idea - but I want to see someone bloody do it - not talk about it. I get the shits because I can read so much info here, but no one can confirm anything - its all hearsay - like the intake manifolds (greddy copy), turbos, etc etc. Is this one just going to be all talk like the rest?

If Mafia had the option of a split pulse housing, with A/R options (important as Cubes said) then he'd have been mad to not go that way - price dependent of course. Useless dreaming though, because there are only so many options, and only one split pulse housing size.

I had no idea about these - but I probably wouldn't have done it anyway to be honest - spending big bucks on the exhaust manifold, external gate, would have moved my turbo upgrade from $2000 to over $4000. And I wasn't interested in removing the exhaust manifold, I wanted the stockest looking 300rwkw I could get

How does yours put the power down, and what did you do (if anything) to make it better?

Well, mine is a little agressive, can't keep the car straight until I hit about 120kmph. I think I am going to need to invest in some decent rubber and get back to everyone.

Nismo 1.5 way (not a pro) It's a bit tighter than i'd like really, but it's still pretty new so it might soften up a bit with a few more km's

keep us updated - I'd maybe like to try something like this. Sick of the back end going spastic when it breaks traction.

Edited May 21, 2007 by The Mafia

[Cubes]

Hey dale, I've had a look at the inlet manifold and are now wondering where I would put the WMI nozzle if I Was to put on one of those cast Greddy copies. Cubes has also notified me in a PM that I need a bigger intake chamber if I was to move to the 3.0l bottom end. THis is interesting - and if anyone could elaborate on this particular point I'd be interested in what they have to say.

Its not that you need a larger inlet manifold its that the std item is 'tuned' for the 2.5ltr so its not optimal and causes power to nose over a little early which essentially leaves you with a narrow power band when running a GT35R + sized turbo.

How a plenum affects power with a smaller GT30r I'm not sure as I've only ever seen results of GT35r's on the 3ltrs.

R33_racer and another here on SAU have ran GT3040's with plenums and had no issues with power nosing over early (before 6000rpm) in the rpm so I suspect confidently the same goes for my gt30r. Once its all sorted I will be performing a few back to backs using a CPC plenum.

I had a thread some time ago where I shared the results but some were skeptical and completely missed the point I was attempting to illustrate. One or two including a well known workshop jumped in to the thread and stated they have had the std plenums pushing 350rwkw+, yes big deal its not the topic of converstation. It was about power placement through out the rpm and how inlet runner/plenum tuning affects this.

Manufactures have been tuning inlet systems to play with power/torque at the rpm required when taking in to consideration gearing, drive type (sports or lazy family car) etc.. So I really don't see what the dispute was about.

http://www.patentstorm.us/patents/5003932-description.html

[discopotato03]

Mmmm I'd dispute the part about have to be on boost to do any good . In part throttle operation often the inlet manifold pressure is lower than atmospheric where the exhaust manifold pressure is almost always higher . The pressure differential is not going to do you any favours - sort of EGR action I suppose . Any serious NA engine even production ones in some cases use decent pulse divided headers/extractors .

I won't argue that a properly specced twin scroll turbo on an RB25 will do better than a larger single scroll on an RB30 but we are not talking about a bolt on either . I aimed for the RB26 head on an RB30 because I think an RB30 needs all the port and valve area it can get to justify the extra 20% capacity . Getting way off topic but many agree if they did the RB30 DOHC again it would have the best head . Tearing up 10G's very easily .

Hell I already own the 26 top end and the delux JE pistons and gapless rings but I still think my R33 will get the HKS manifold/gate and some sort of twin scroll turbo .

My problem is that I can see this car costing a bomb and not getting upwards of 30G when I'm finished with it . I've noticed that people here generally have to sell the RB30 separately to get anything worthwhile and then re power the car to sell it . Lot of work for lot of loss IMO .

Bolt on bits unbolt and std bits rebolt so this is the issue .

My other big issue is that an R33 is no flyweight and while impressive power can bolt in how do you get it to the ground ? The answer is obviously all wheel drive and thats not an economic reality in a 2WD Skyline . It urks me to say it but smaller /lighter AWD cars are out there with similar power to weight ratios BUT 100% of that weight is available for traction .

I also think to have a road rocket that won't put you in gaol needs to have giddy acceleration out of the blocks to feel great and not smoke your points - too quickly . No AWD Skyline is what you'd call light and this is probably a big part of why the Evos (and Rex's possibly ?) beat the GTR's in production class motorsport . If the legend can be beaten I don't need to explore the limits of great power but with less that half an R33's 1380 odd Kg over the driving wheels .

I still believe I can get enough power from the sold in the car engine to make it a nice drive and not shred the treads too much . For me any more is pointless and the money I'd rather have in the bank .

Truly sorry I'm not printing the stuff , cheers A .

[The Mafia]

Disco I understand where you are coming from but I'm not talking about a RB26\30 with 500rwkw capability.

I'm talking about a mildy ported RB25 head, on a RB30 bottom end, running RB30 rods, balanced, BT30r or maybe a GT35 at low boost, running about 300rwkw to 340rwkw.

The torque wuld be fantastic, top power would be enough, and you'd be able to control the wheel spin. You wouldn't need this head that breathes like a hurricane, just something to do the job you're after. I'm planning on doing this, and it shouldn't blow $3k.

As for your comment on the twin scroll not needing boost - HOw is it going to make power then? Making a change to the turbo isn't going to do jack all to the car off boost. You might get a 5% difference to this different design of manifold, but hardly noticable? The 3l simply has it all over the twin scroll in all areas, and if you already have a decent turbo, thats even better.

So basically, a simple 3l build

Forgies (or even standard pistons),

Standard rods

Standard oil pump (with the extra return plumbed, and feed blocked)

Standard exhaust manifold (maybe honed a little)

GT30r, (or maybe a GT35 if you want to upgrade a touch more)

These are the things you should already have:

ECU

Fuel pump

FMIC

Exhaust

I'd rather the torquey off boost balls the 3.0l has, even if its just a touch more expensive. Oh, and its a complete rebuild, so thats something you don't need to worry about for a loooong time.

[Adriano]

Without having data of ex manifold vs inlet man pressure at low load levels, there is really no way to know how much difference to the off boost torque developed. However slight, a reduction in ex man backpressure would allow an increase in cam overlap, and volumetric efficiency. However saying that, rb30det's tend to get significantly more power with no boost (usually 130rwkw) than a standard rb30, even with their lowered comp ratio. This indicates the backpressure of the turbo doesnt significantly affect developed power/torque. I think it would be interesting to see how much could be gotten out of a gcg/slide highflow with the WI, as from my experience they seem to end up running into detonation problems when trying to give them any real timing, especially on the NEO

[Cubes]

Disco, you worry too much.

There's no need to spend BIG $$ on an <300rwkw RB.

A stock rb30e bottom end with a rb25 head and gt30 turbo fits your requirements nicely.

Start throwing pistons and rods at it and you throw the bang for buck well and truley out the window.

Pistons and rods for less than 300rwkw simply isn't required.

If you get tired of shifting up at 6500rpm throw a plenum on it, loose nothing thats noticable down low or through the mid only to extend power through to 7000-7500rpm on stock cams. Plenty good and a sporty pleasure to drive.

The 26 head is a better starting point as you don't have to spend extra on a decent plenum; it already has one.

The problem with the 25 head isn't the head its self, its the inlet tuning.

A couple here in Adelaide that ran good power on stock rb30 bottom ends.

Sky30 - 370rwkw (a 310,000km rb30 at that lol)

s3girl - 471rwkw

Both have rev's limited to 7000rpm as its not wise reving 7500rpm+ on stock rods with nissan bolts.

[Dale FZ1]

I don't think anyone doubts the brutal efficiency of the rally rockets. They are short, relatively light well powered and put it to the ground. For me, the 2wd Skyline was all about how it FELT to drive. Balancing traction and drive coming out of a bend (not just a tight roundabout) with something reasonably powerful (or really powerful) is what the experience is all about.

Having said that, every grass motorkhana I go to, I rue the decision to pass up a R33 GTS4 for a lot less money.

Surely the intelligent thing to do is target a certain power level, and aim to make it as progressive and driveable as possible. Good torque both on and off boost is the key, and in the engine speed range that we use. Cubes is right on the money with earlier posts about that. I don't need 300kW, but at that level, the cubes certainly count for something.

And I think that regardless of engine size, putting it to the ground is most important. How about some real discussion on this point? Surely there are more people than BHDave that have had to deal with this.

Edited May 22, 2007 by Dale FZ1

[BHDave]

Nah, I'm the only person on the forum who's scared of going sideways

If you got in a 33gts4 and took it for a spin, i think you'll be very happy that you got the turbo rwd one.

I never set out to achieve a certain power figure either, I just got the urge to buy a hks low mount kit that a mate had sitting in his back room, and then once installed, i just wanted to make the most out of it i could. If my stock turbo hadn't popped i'd still have a stock turboed rb20 pushing 165rwkw and i'd be a happy boy as it was a fun car to drive.

[Cubes]

The skylines (well mine at least) actually tracks pretty damn straight when turning both rear wheels. Just an ever so slight twitch to the left or right and sits there.

My old VS 5ltr 5speed (ecu cam done) used to tank slap all over the road, it was quite dougy under 3000rpm due to the cam but once it cleared its throat it went well.. :S

The little skylines is extremely easy to handle with that respect. And it is all about the drive as Dale has said.

I sold the v8 as it didn't provide that lunge out of a corner as the turbo'd skyline does. Nothing beats its.

An uncle of mine has a LS1 285kw senator; I was quite dissapointed how dull it was pulling out of corners. It just didn't have that wow its really wanting to break loose type feel. It just wound out slowly. My old VS was much more fun.

Probably a combination of the added weight of the new commo and what felt like longer gearing. Just didn't 'feel' fast.

[MBS206]

My skylines snaps sideways and generally wants to sit out there, quite "scary" at times. And I'm only pushing 250RWHP...

Plan: Reshim diff. If that doesn't work.

1.5Way LSD

[discopotato03]

Mafia my train of thought is that it will work better everywhere because the cylinders can exhail so much more easily throughout the rev range . A turbine housing is really just an extention of the exhaust manifold and in the RB25's case this is where the pressure rise occurs and cross contamination takes place with the single scroll housing . The twin scroll housing takes the exhaust path of each pair of 3 cylinders all the way to the nozzles - just like an RB26 does . The main difference there is that the twin turbines are only getting an exhaust shot half as often as the twin scrolls single turbine does .

By off boost I mean sub atmospheric inlet manifold pressure , and the higher exhaust gas velocity (gas always flows from an area of high pressure to lower pressure faster when the pressure difference is greater) to enhance that windmill effect (compressor pushing more air into the engine than it would get if it was only being charged by atmospheric pressure alone ) .

BTW someone mentioned only one available TS A/R ratio and thats not the case . There is another family of TS housings thats being used OS in .82 and 1.06 A/R . You get a leg up with the cast HKS manifold because it has the larger T4 flange but with split T3/T4 Euro ports and stud hole pattern , in other words if you found a split T4 flanged housing in the ratio you wanted you simply drill and tap four more holes and bolt it on . Hint , its not uncommon to find TS T4 flanged housings with split T3/T4 Euro sized ports in them .

Cubes I'm in no great hurry with my Skyline , I fully intend to do lots of stiring in the sorts of places that may get noticed so with a bit of luck and a tail wind we may get Garrett (or aftermarket) TS turbine housings with the twinned passage/swing valve integral wastegate . Just like the single scroll integral gate housings were TS ones really are the missing link . Could you imagine what the demand for such a thing would be if it was made available ? Who would bother with the ordinary housing ? I have mentioned in the past that Brett Lloyd said Garrett have no intention of making them but if they thought the volume sales were there who knows ? The single ones we have are manufactured here in Australia not the US or Japan , admittedly they had the advantage of having a similar OEM (Ford XR6T) to work off . Can someone please tell Mr FoMoCo how much better a TS GT35R integral housing could make the XRT6 go ...

ATM the best I can do is put feelers out round the world to see what sort of interest (sales potential LOL) exists for TS/split integral wastegate GT30 and GT35 turbine housings .

My current daily will probably get a TS turbo before the Skyline but thats OT so I guess we need another TS thread .

Cheers A .

[The Mafia]

Mafia my train of thought is that it will work better everywhere because the cylinders can exhail so much more easily throughout the rev range . A turbine housing is really just an extention of the exhaust manifold and in the RB25's case this is where the pressure rise occurs and cross contamination takes place with the single scroll housing . The twin scroll housing takes the exhaust path of each pair of 3 cylinders all the way to the nozzles - just like an RB26 does . The main difference there is that the twin turbines are only getting an exhaust shot half as often as the twin scrolls single turbine does .

By off boost I mean sub atmospheric inlet manifold pressure , and the higher exhaust gas velocity (gas always flows from an area of high pressure to lower pressure faster when the pressure difference is greater) to enhance that windmill effect (compressor pushing more air into the engine than it would get if it was only being charged by atmospheric pressure alone ) .

BTW someone mentioned only one available TS A/R ratio and thats not the case . There is another family of TS housings thats being used OS in .82 and 1.06 A/R . You get a leg up with the cast HKS manifold because it has the larger T4 flange but with split T3/T4 Euro ports and stud hole pattern , in other words if you found a split T4 flanged housing in the ratio you wanted you simply drill and tap four more holes and bolt it on . Hint , its not uncommon to find TS T4 flanged housings with split T3/T4 Euro sized ports in them .

Cubes I'm in no great hurry with my Skyline , I fully intend to do lots of stiring in the sorts of places that may get noticed so with a bit of luck and a tail wind we may get Garrett (or aftermarket) TS turbine housings with the twinned passage/swing valve integral wastegate . Just like the single scroll integral gate housings were TS ones really are the missing link . Could you imagine what the demand for such a thing would be if it was made available ? Who would bother with the ordinary housing ? I have mentioned in the past that Brett Lloyd said Garrett have no intention of making them but if they thought the volume sales were there who knows ? The single ones we have are manufactured here in Australia not the US or Japan , admittedly they had the advantage of having a similar OEM (Ford XR6T) to work off . Can someone please tell Mr FoMoCo how much better a TS GT35R integral housing could make the XRT6 go ...

ATM the best I can do is put feelers out round the world to see what sort of interest (sales potential LOL) exists for TS/split integral wastegate GT30 and GT35 turbine housings .

My current daily will probably get a TS turbo before the Skyline but thats OT so I guess we need another TS thread .

Cheers A .

1. Nobody challenged your view about the .78 housing being like 2 x small .38 housings in one. In fact, it is a .78 being fed by 2.5 litres in total. The improvement in response is apparently due to the non interference of opposing pressure waves that assist to draw exhaust from neighbours. Can you find a reason why Nissan/Garrett engineers chose not to divide the OEM housing on RB20/25 when their manifold IS divided?

2. I will give some ground on the idea of better off boost response for a properly designed split pulse system - which means it would HAVE to have runner length + diameter specified for the application (power + rev range) - because it is sort of emulating a PROPERLY engineered set of extractors on a N/A car. Mostly it's a bit like splitting hairs though.

3. I have used four different A/R housings, and settled on the smaller one because of unacceptable lag. I've used a butchered VG30 housing, a butchered RB25 housing, a Garrett .82 housing, and a garrett 0.63 housing. Fair enough you're saying "yeah there ARE options" to prove the point - but they're all bigger. So what is achieved? More top end power, but more lag down low because the gas velocity through the housing at low engine rpm is too slow to accelerate the rotor.

But ultimately, we really need to divide this into another thread because it really has absolutely nothing to do with what I have achieved - 300rwkw, that is very usable, and not too laggy, with a very simple budget.

Lets start discussing diff options, and things like that eh?

Edited May 23, 2007 by The Mafia

[skyguy61]

Hey Mafia,

Just curious how different your results would be without Methanol in power, knock and timing using the WI ? I read ages ago about your WI and the gains you made and thought you were on the right track ,excess HEAT in the cylinders is our enemy

. great read guys keep it up. cheers