-5's Vs Rs's On A Larger Then Stock Motor

[JAGR33]

JAGR33

No l did not buy the car from a previous Racepace customer and all the mods that have been done to the car were done by Racepace. As for taking it back there for another dyno run l am have not done that as yet but, l have placed it on another dyno just for a comparsion and result l got has really pissed me off and confirms my suspicion that the figure l have been given and using the amount of standard components on the car is misleading and from a over inflated dyno. As for your comment as something may not be right, everything has been double checked and turns out to be O.K. I understand your point that peak power is what is required for a quick drag car, but given the claimed power figure l got from the Racepace dyno the car should if everything else is perfect dispatch a high 10 second pass. Going from other cars as an indcation some having less power than my car it is far from it. I will take it back to Racepace after l have claimed down to see if they can find a problem.

Did you put your car on a 4wd dyno? That usually shows a lower figure than in 2wd mode.

I can understand your frustration but let me tell you this, don't take dyno figures as gospel, they are a tuning tool and each dyno and dyno operator is different.

Also having 380rwkws does not give you a high 10 sec pass, there are many other factors that play a big role. Have you taken it to the drags? If so what time and most importantly what mph?

Also do you have a copy of the dyno sheet? Or were you just 'told' that's what power it makes?

Sorry Piggaz for the hijack, but back to your dilemma I'd say at the level of power your at it wouldn't hurt trying out the bigger dumps, we all need a guinea pig!!!

[R31Nismoid]

Did you buy the car from a previous Racepace customer or did you have the mods done yourself? Seems like you're not convinced with the power claims so why not take it back there and get another dyno run? Maybe something is not right, maybe there's a boost leak there could be something holding it back hence not feeling the claimed 380rwkws.

Nothing I haven't told him on 3 occasions now since Aug 2010, even earlier it think.

My purpose was to have a quick street car that has the ability to run a 10 second pass

Nismoid, my car is making a "claimed" 380RWKW on 25 psi of boost and was built and tuned by the same guys that have done your car.

As for taking it back there for another dyno run l am have not done that as yet

So basically what you are telling us is that 6 months down the track.

You haven't taken it to the track yet? Or back to Racepace? Or anything?

MPH would soon tell the story. Taking it back to Racepace would as well.

So how about you stop complaining and go and get it looked at?

I know if I felt as strongly as you come across, then I'd have taken the car back there in a week. Not 6 months.

[R31Nismoid]

After having a look around at dumps the Midori Seibi items look like a goer. Internal Diameter of 76.3 mm which is 3 inches. Bigger then the new Tomei items which are 68, the Mines which are 70 (split type) and I would assume the Nismo's. From what I can gather the Series one Tomei's were 2 and 3/4 inch internal diameter.

How much/where from?

Very rare to find such big dumps these days, most are all but discontinued!

[Nee-san]

piggaz, I have had some success on 2 cars of mine with the tomei manis and found they seemed to make a difference even with GTSS turbos as they spooled up very hard with the tomei mani's. the aim is to get that exhaust gas hitting the turbine wheel hard by giving it the most direct path possible, but given how much pressure there is between head and turbine in the manifolds design is probably not so crucial but the tomeis do have much bigger runners. having said that the stock manifolds should not really hold it back at all. they have their good points too. being thick cast mani's they keep much more heat (energy) in the pipe which is desirable too. there is no doubt they are good enough. on my two cars that I used tomei mani's on they held up fine while I had them and I know one car that has been running now about 3 years with them still good. BUT on the flip side I have heard of a few tails of cracked ones too. there are a few factors in that. a lot of people done have a bracket to hold up the front pipes which means all the weight of the turbos, dumps and front pipes are hanging on the mani's. EGTs is another big factor as is engines that get shut down hot without a "warm down" period to let temps normalise slowly. that can and will crack the manifolds.

Have you considered switching to a set of GTS4 diff gears? they are a great match with the OS gearset you have and will shift your power graph in the right direction speed wise.

The key thing I've found to get the best out of the twins (be it GTSS, 2530, or GTRS) is getting the gas in and out of turbos as well as you can. I would reccomend a set of stock ported or tomei mani's, a set of tomei big bell mouth dumps (or other comparable ones but I've never seen others as big as the tomeis), matched to the BIG HKS front pipes (there are small ones and big ones, you need the big twin 70mm into single 90mm ones), with a free flowing cat or pipe and a free flowing exhaust.

same goes for the intake. you want a nice smooth passage for that compressed air from the turbos to the inlet. you can keep the stock inlet piping and twin turbo pipe but replace the other intercooler pipes for a hard pipe kit (not expensive). nismo plenums are good too but I've never seen much top end power increase from them, but they definitely help with response which is not easily measured on a dyno(on/off/on throttle and a bit of midrange gain too). you can also got a full suction kit if you like, I'm a fan of them but they are a bit expensive from HKS or trust so on a dollar to improvement basis they are not a necessity. A good intercooler is important too. These days I don't see a reason to use anything much other than ARC. they are amazing. Their 70mm cores are easily good enough for a 350+kw circuit car and are lighter than a standard core, and allow plenty of air through to the radiator too (something not many people conider when they jam a massive 180mm thick core in there). the 100mm ARC cores are good too if you need something with a bit more volume.

Obviously tune is key too but again it's a bit hard to quntify. you just have to hope that the tuner you choose is doing the right stuff. from memory you have a fairly reputable one.

to sumarise, my suggestions to get twins working hard on a GTR:

mani's are not crucial but ported stock is good and I've had good results with tomei too

BIG dumps are important, I do not like the small split dumps, even the genuine HKS ones

BIG front pipes are important too. I don't like the everyday china twin 60mm ones, try for something bigger

the rest of the exhaust is important too. you want that gas to have a nice free path out.

inlet piping is less important but still some thought should be given to it.

intercooler is important. get a good one.

the tune, and tune some more.

but if the turbos are just not suitable for the package then it will never be right. a set of -5s or 2530s would probably wake your car up. Look at the change in Gav's car.

don't stress though, you'll get there.

I have Xforce splits on my car, now I'm worried, your not going to make me spend more money are you Mr Baron !

[paulr33]

http://www.nengun.com/midori-seibi/outlet-pipe-gtr

[R31Nismoid]

I meant well priced lol

Rarely is nengun cheap these days it seems

[Piggaz]

Sorry Piggaz for the hijack, but back to your dilemma I'd say at the level of power your at it wouldn't hurt trying out the bigger dumps, we all need a guinea pig!!!

Haha. Yeah thats fine. There will be a little bit of testing going on with my car this year. Different cams (260's and 270's back to back) and now it looks like big fook off dumps with a set of -5's bolted to them!

How much/where from?

Very rare to find such big dumps these days, most are all but discontinued!

Ash, Straight off good ol Nengun. About $850 off delivered. I might see what a mate of mine can get them for... Usually 20-25% off RRP

Greenline dont have them.

I dont think I have ever seen a car with these dumps on them. Maybe because alot of companies dont make a front pipe big enough (a proper 3 inch internally diameter). My HKS ones are 70 mm so there will be a lip now. ATM when you take the front pipes off the car the size difference between the rear of the dump to the start of the front pipe is huge. The dumps are that much smaller it isnt funny..... Now if i buy these Midori ones it is going to be the other way round. Dammit!

[R31Nismoid]

Yeah most of the time if you want a 3" front it's gotta be custom. equally as rare to find them off shelf.

ideally though you need at least 3.5", preferrably 4" anyway dude in terms of exhaust - time to do it all at once

[JAGR33]

WOW those Midori dumps look the goods, well priced aswell....

Piggaz, definetly recommend going bigger exhaust, although you don't want the noise to go with it. My Racepace jobbie is twin 3inch after the dumps (have Xforce dumps) all the way to the tail pipes using single muffler half way and another at the rear. in other words the twin pipes enter and exit one muffler. Sounds reasonably quiet and flows really well.

Anyway look forward to your results....

[elrodeo666]

Paul

Mate I have the HKS 2.8 Step 2 plus -5's , Hypertune plenum and have over 600 plus hp.

Running standard Nissan but custom match ported and polished exhaust manifold by HKS , plus Tomei dumps.

Also heavily modified head with 264 cams with all work done by HKS and Naprec .

The car has stacks of response.

They recommended me stay away from HKS & Tomei manifolds as they have issues with cracking. Not all of them but a lot do.

Also told me not to use the HKS dumps but go the Tomei. My engine builder there does not try to sell you company products but what he knows that works and has no problem giving the thumbs up to other brands.

He also is big on running standard manifold but match ported and polished on anything up to 700hp. On big hp engines he makes custom pipes.

Funny here a lot of people in Oz keep going on about the old Tomei dumps due to the fact they are larger diameter but the new type are different design and made of different material.

The new type are designed to flow better and faster than the old larger diameter design.

I still have a secret part to install which will give me another big hp shot. Its olive black, weighs about 9kg, good for 2000hp and vibrates like a vibrator on crack !!

[bodge]

Did you put your car on a 4wd dyno? That usually shows a lower figure than in 2wd mode.

I can understand your frustration but let me tell you this, don't take dyno figures as gospel, they are a tuning tool and each dyno and dyno operator is different.

Also having 380rwkws does not give you a high 10 sec pass, there are many other factors that play a big role. Have you taken it to the drags? If so what time and most importantly what mph?

Also do you have a copy of the dyno sheet? Or were you just 'told' that's what power it makes?

Sorry Piggaz for the hijack, but back to your dilemma I'd say at the level of power your at it wouldn't hurt trying out the bigger dumps, we all need a guinea pig!!!

Car was placed on 2wd dyno and have the dyno sheet. It was also taken to the drags and the best MPH was 121.

As for Nismoids reponse, the car has been checked over by another place for the simple fact l wanted a second opinion, and will take it to Racepace when l have time.

[Don Dada]

Fuel system is 1 Nismo intank pump feeding surge tank with 2 x Tomei (Walbro) pumps

[Beer Baron]

pigaaz, yeah the midori dumps are good and remarkably 'similar' to the old tomei dumps... the new tomei dumps are good too and definitely stronger being cast but they are sadly a little smaller. check which HKS front pipes you have. one way to tell is the newer BIG ones have the flanges welded to the pipes on the inside. so instead of seeing welds around the outside of the flange where it meats pipe there are just 2 small tack welds. from memory they are about 75mm or more each pipe into single 90mm.

plenty of people have made good power (or claimed to) on stock 32 dumps but on any car of mine that I've changed them on it certainly seemed to go much better with bigger ones. the only car I've owned with HKS dumps is the one that's currently not quite making the power it should. so I dunno?

Midori is one of the top 10 GTR workshops in the world for sure. they charge like wounded bulls but their gear is amazing. all their stuff works and is top shelf. I do not mind paying for quality.

[bigmikespec]

Do the Midori front pipes go from a Ø76.2mm internal diamter then merge? You can order them to merge into a Ø80mm or Ø90mm outlet.

[Piggaz]

Paul

Mate I have the HKS 2.8 Step 2 plus -5's , Hypertune plenum and have over 600 plus hp.

Running standard Nissan but custom match ported and polished exhaust manifold by HKS , plus Tomei dumps.

Also heavily modified head with 264 cams with all work done by HKS and Naprec .

The car has stacks of response.

They recommended me stay away from HKS & Tomei manifolds as they have issues with cracking. Not all of them but a lot do.

Also told me not to use the HKS dumps but go the Tomei. My engine builder there does not try to sell you company products but what he knows that works and has no problem giving the thumbs up to other brands.

He also is big on running standard manifold but match ported and polished on anything up to 700hp. On big hp engines he makes custom pipes.

Funny here a lot of people in Oz keep going on about the old Tomei dumps due to the fact they are larger diameter but the new type are different design and made of different material.

The new type are designed to flow better and faster than the old larger diameter design.

I still have a secret part to install which will give me another big hp shot. Its olive black, weighs about 9kg, good for 2000hp and vibrates like a vibrator on crack !!

Steve and I have spoken about your car a few times. Your result is spot on. Whats even more surprising is they used -5's and not 2530's or something else off the shelf "jap". Who's call was that? Was HKS impressed with the result the 5's gave?

pigaaz, yeah the midori dumps are good and remarkably 'similar' to the old tomei dumps... the new tomei dumps are good too and definitely stronger being cast but they are sadly a little smaller. check which HKS front pipes you have. one way to tell is the newer BIG ones have the flanges welded to the pipes on the inside. so instead of seeing welds around the outside of the flange where it meats pipe there are just 2 small tack welds. from memory they are about 75mm or more each pipe into single 90mm.

plenty of people have made good power (or claimed to) on stock 32 dumps but on any car of mine that I've changed them on it certainly seemed to go much better with bigger ones. the only car I've owned with HKS dumps is the one that's currently not quite making the power it should. so I dunno?

Midori is one of the top 10 GTR workshops in the world for sure. they charge like wounded bulls but their gear is amazing. all their stuff works and is top shelf. I do not mind paying for quality.

My fronts im 99% are twin 70's into a 85. Apart from the Midori front pipes they are the biggest ones I have found. Don't Racepace sell some crazy front pipes?Tangomatt had some on his car im sure of it. I wonder what they would want for a set of them?

I'll be getting a price for these Midori dumps over the next few days. I aint paying almost $900 for them.

[elrodeo666]

Steve and I have spoken about your car a few times. Your result is spot on. Whats even more surprising is they used -5's and not 2530's or something else off the shelf "jap". Who's call was that? Was HKS impressed with the result the 5's gave?

My fronts im 99% are twin 70's into a 85. Apart from the Midori front pipes they are the biggest ones I have found. Don't Racepace sell some crazy front pipes?Tangomatt had some on his car im sure of it. I wonder what they would want for a set of them?

I'll be getting a price for these Midori dumps over the next few days. I aint paying almost $900 for them.

-5's was my call after talking to a few people including Gav and Russ and seeing their response off their cars.

Initially they wanted to go 2835's plus V-cam but that would have meant growing another a#@$hole.

When I chose the -5's they then pushed me to go the 2530's but after the car was all said and done they were impressed with the performance of the -5's .e.g holding boost a bit longer than the 2530's.

My mate at HKS has built that many top performance engines in Japan, that if he has a list of parts in front of him and engine and head combo and mod work he has to do, that he pretty much knows what power output to expect but was quite surpirsed by performance of the -5's on my 2.8 setup.

HKS have a new V-cam system setup that you can run quite big cams which would have your car hauling arse with your current turbo's.

I'd love to see that V-cam on a good 30/26 setup.

I still havent got mine on the road here but doing some work on it yesterday and had a couple of squirts up my street and it definitely gets very squirrely.

Once I get it all sorted with rego, definitely like to try E85.

[Piggaz]

The thing with the V cam (as much as I would LOVE to have it on my car....as would all of us) is with the big one for turbo's like T04Z's, GT RS's is that you need valve relief pistons. I dont have that and I am not pulling down a engine to fit them! Its interesting that the -5's hold boost longer then the 2530's.

Your car made 440rwkw off the top of my head? That enough to scare most people

[SimonR32]

All this talk about super expensive dumps, front pipes and hard piping kits... And people say that twins are cheaper than singles tisk tisk

Edited January 14, 2011 by SimonR32

[Piggaz]

All this talk about super expensive dumps, front pipes and hard piping kits... And people say that twins are cheaper than singles tisk tisk

Nah ah. GTR's are twins. Period. Its all about looking "stock" *ah hem*.... for when the super doods in their crazy SS's pull you over and say 'pop your bonnet son" .

You sound like my tuner.... He calls twins "Thomas the tank engines" becasue they choof! Its all about no no no to singles and yes yes yes to twins haha

[paulR32gtr]

Do the Midori front pipes go from a Ø76.2mm internal diamter then merge? You can order them to merge into a Ø80mm or Ø90mm outlet.

Yes I believe so - both versions are designed to match up to the midori dumps.