-7/9s Or -5s Garretts

[Nee-san]

I'm really glad we all see eye to eye on this, as I think it's an issue thats massively understated.

Alot people seem to only be interested in making huge power and not fully understanding the considerable effects turbo selection plays on vehicle dynamics, gives turbocharging a bad rep...

[GT-R32]

Torque is good for talk, power makes you move. Something doesn't even have to move to make torque. You're all talking about average power, not torque. We're not motoring journos or V8 heads here, we can choose to get it right.

http://www.fjr1300.info/misc/torque-power.html

[GTRsean]

From my project thread:

The 2860-9's are what I'd thought they'd be like . Great response, meaty mid range and revs out nicely. It's running at 17psi, 1.2BAR on gauge is maxed out lol, injectors are at 90% and knock has a peak of 22, yet to be tuned but runs great.

In 6th gear I see 0.8bar, 12 PSI at 3000RPM. The way it comes on boost is impressive considering the stock cams, manifolds etc. The engine had cam gears already fitted so I haven't touched them.

Pulling out of corners, it just accelerates, so no real problem being in a higher gear too.

So I rate the -9's! just my opinion, and I have had 2 RB26's and 5 different sets of turbo's to compare with over 6 years.

[R31Nismoid]

In 6th gear I see 0.8bar, 12 PSI at 3000RPM. The way it comes on boost is impressive considering the stock cams, manifolds etc.

IMO that is the best way to do it, stock cams and manifolds etc.

Plenty of meat in the lower RPM

[usmair]

From my project thread:

The 2860-9's are what I'd thought they'd be like . Great response, meaty mid range and revs out nicely. It's running at 17psi, 1.2BAR on gauge is maxed out lol, injectors are at 90% and knock has a peak of 22, yet to be tuned but runs great.

In 6th gear I see 0.8bar, 12 PSI at 3000RPM. The way it comes on boost is impressive considering the stock cams, manifolds etc. The engine had cam gears already fitted so I haven't touched them.

Pulling out of corners, it just accelerates, so no real problem being in a higher gear too.

So I rate the -9's! just my opinion, and I have had 2 RB26's and 5 different sets of turbo's to compare with over 6 years.

Sean it would be interesting to compare your results with mine

Our mods are very similar, however I'm only running 15psi due the AFMs and Injector limitations... getting 270rwkw as it is

but I am surprised at how laggy my current setup is... im seeing full boost around 4500RPM which is pretty damn laggy..

must be the restrictions in the exhaust (only catback with compliance cat)

I would like to compare your power delivery with mine

be sure to put up results!

[Count Grantleyish]

I have GT-SS (aka -9).

They're fantastic turbos to have. I have 302.8rwkw @ 18.6psi (will need to put up the dyno sheet) with these turbos along with Cam Gears, HKS front pipe, gutted cat (good for flames as I found out @ club cruises) HKS 3.5" cat-back exhaust and pair of HKS pod filters (I know, haven't bothered trying to source a stock airbox).

Injector duty went 91% cycle while tuning, and other night went home from work I hit 92% so I'm in search for bigger injectors, Nismo AFM and decent EBC (I still have stock injector and AFM atm).

Usmair, what are you doing with compliance cat and I'm assuming a stock front pipe? Change them ASAP!!!

[usmair]

haha yeh Franga... only cat back

the turbo upgrade were unexpected... the standard ones went so got the -9s

im just going to leave it as it is for a months... but hopefully the full exhaust helps with lag...

going to focus on seeing some more digits in the bank account

[discopotato03]

Torque is good for talk, power makes you move. Something doesn't even have to move to make torque. You're all talking about average power, not torque. We're not motoring journos or V8 heads here, we can choose to get it right.

http://www.fjr1300.info/misc/torque-power.html

Yes as Tom said torque is a measure of turning force and it can be a load measured at zero speed . The thing is that once that turning force overcomes all forms of resistance its what creates rotation .

The points I've been trying to make are where in a given engines usable rev range adequate torque exists to drive you down the road adequately and have more potential torque just a light throttle squeeze away .

I think I can truthfully say that chasing higher than normal revs to have the above mentioned situation is nothing to boast about . Tom is quite right in what he said about torque and gear ratios/wheel diameters , an engines torque peak is where maximum torque output occurs but if the wrong ratios are not used/fitted the torque Multiplication won't be ideal .

Another point I'll spell out involves turbo performance (response) vs engine speed and torque delivery .

A well thought out and sized ball bearing turbo idles or windmills at reasonably high speeds even when engine load is not high or throttle fully open . There obviously is a point below which even wide open throttle (WOT) won't produce a lot of torque or acceleration - the engine can't because it isn't venting enough exhaust heat/velocity energy to spin the turbine/compressor rotating groups fast enough to do much .

The BIG question is are people going to be practically minded enough to chose turbos that will produce some part throttle extra air and engine torque (Plan A) or are they biasing their engine spec on what happens at WOT and 4-8000 revs (Plan B) .

In my opinion there are turbochargers for RB26/GTR that try to achieve Plan A and I personally won't bother deciphering why people opt to do much else on an almost totally street driven car .

These 707160-9 turbos have most of the smarts to be better everywhere than any of the OE RB26 turbos - except maybe the R34 GT2556Rs right down low .

The nice light NS111ish turbine in the smaller 62T trim size , the low friction BB center section , the obviously dialled in 56T 59.6mm compressor wheels . Blind Freddy can see that Garrett didn't put large housings on these turbos like they do at times with single GT25/GT28 BB turbos but then again they aren't often going on the side of effectively an inline three cylinder like parallel twins on an RB26 do . Actually that's not strictly true because an inline three's continuous cycles don't have the extended pause between exhaust events like an I6 divided in half between 3 and 4 does .

Engines that make extra part throttle torque from forced induction are always nicer to drive because they tend to feel linear and more like a larger that std capacity NA engine . You can't escape the fact that this is because the engine torque is increasing earlier in the engines rev range than either no forced induction or turbos sized too large to achieve this . The bottom line is that a 2568cc 8.5:1 CR engine is not going to be impressive with just atmospheric pressure to charge its cylinders (minus any inlet system losses that is) trying to drag around an almost 1500 kilogram Skyline . Without the dryers they would be a total slug , when the dryers don't do anything for whatever reason including sizing it's the same deal .

Just on Toms long vs short stroke myth theory .

Fact 1) How often would anyone increase the stroke and reduce the bore size ? Not too often I'd think .

This gets bandied around a lot but I think essentially the question being asked is will my engine make more torque low down if I increase the cranks stroke . My thoughts are that provided the rods don't get ridiculously short yes it should make more torque down low because the cylinders capacity has increased - in theory more air and fuel to compress and then burn . You'd have to say that increasing the stroke of an engine that the factory had already done this to might be doubtful but if you cant increase the bore size and revs are kept low it may be the only way .

I don't look at an RB30 as a long stroke engine , I do look at an RB26 as being long in the stroke for the deck height of the block which means shortish rods etc . AFAIK the RB20 was the original and smallest of the RB engine family and they pinched their bore/stroke dimensions from the old L series L20a .

In some ways I wish Nissan had used a taller deck height on RB25s and RB26's but they obviously wanted to stay within the external dimensions of the RB20's block . Plainly it was never going to work with a 3 litre engine and the bore centers are not wide enough in the RB family to increase it significantly .

My thoughts are still the same , turbos sized to drag torque out of a 26 lower than Nissan had it or throw an RB30 at it .

It's still possible to drive enthusiastically a car that's makes good torque without too many revs , lots of haul without necessarily warp 9 velocity . Get in a car that's a Honda Zot up to 3500-4000 and see how fast you're going when you get to the meaty part of the rev range in 1st and 2nd gears .

In the excitement wave to the cop or contractor in the plain white Territory with the dinky little radar dish on the roof .

Six cars a second they are claiming they can nail at any one time .

Race spec cars are useless to me on the street .

A .

[Nee-san]

Im glad you replied disco, saved me a big write up Lol

Another point I'll spell out involves turbo performance (response) vs engine speed and torque delivery .

A well thought out and sized ball bearing turbo idles or windmills at reasonably high speeds even when engine load is not high or throttle fully open . There obviously is a point below which even wide open throttle (WOT) won't produce a lot of torque or acceleration - the engine can't because it isn't venting enough exhaust heat/velocity energy to spin the turbine/compressor rotating groups fast enough to do much .

The BIG question is are people going to be practically minded enough to chose turbos that will produce some part throttle extra air and engine torque (Plan A) or are they biasing their engine spec on what happens at WOT and 4-8000 revs (Plan B) .

In my opinion there are turbochargers for RB26/GTR that try to achieve Plan A and I personally won't bother deciphering why people opt to do much else on an almost totally street driven car .

These 707160-9 turbos have most of the smarts to be better everywhere than any of the OE RB26 turbos - except maybe the R34 GT2556Rs right down low .

The nice light NS111ish turbine in the smaller 62T trim size , the low friction BB center section , the obviously dialled in 56T 59.6mm compressor wheels . Blind Freddy can see that Garrett didn't put large housings on these turbos like they do at times with single GT25/GT28 BB turbos but then again they aren't often going on the side of effectively an inline three cylinder like parallel twins on an RB26 do . Actually that's not strictly true because an inline three's continuous cycles don't have the extended pause between exhaust events like an I6 divided in half between 3 and 4 does .

Engines that make extra part throttle torque from forced induction are always nicer to drive because they tend to feel linear and more like a larger that std capacity NA engine . You can't escape the fact that this is because the engine torque is increasing earlier in the engines rev range than either no forced induction or turbos sized too large to achieve this . The bottom line is that a 2568cc 8.5:1 CR engine is not going to be impressive with just atmospheric pressure to charge its cylinders (minus any inlet system losses that is) trying to drag around an almost 1500 kilogram Skyline . Without the dryers they would be a total slug , when the dryers don't do anything for whatever reason including sizing it's the same deal .

QFT

Just on Toms long vs short stroke myth theory .

Fact 1) How often would anyone increase the stroke and reduce the bore size ? Not too often I'd think .

This gets bandied around a lot but I think essentially the question being asked is will my engine make more torque low down if I increase the cranks stroke . My thoughts are that provided the rods don't get ridiculously short yes it should make more torque down low because the cylinders capacity has increased - in theory more air and fuel to compress and then burn . You'd have to say that increasing the stroke of an engine that the factory had already done this to might be doubtful but if you cant increase the bore size and revs are kept low it may be the only way .

I don't look at an RB30 as a long stroke engine , I do look at an RB26 as being long in the stroke for the deck height of the block which means shortish rods etc . AFAIK the RB20 was the original and smallest of the RB engine family and they pinched their bore/stroke dimensions from the old L series L20a .

In some ways I wish Nissan had used a taller deck height on RB25s and RB26's but they obviously wanted to stay within the external dimensions of the RB20's block . Plainly it was never going to work with a 3 litre engine and the bore centers are not wide enough in the RB family to increase it significantly .

Also QFT.

My thoughts are still the same , turbos sized to drag torque out of a 26 lower than Nissan had it or throw an RB30 at it .

It's still possible to drive enthusiastically a car that's makes good torque without too many revs , lots of haul without necessarily warp 9 velocity . Get in a car that's a Honda Zot up to 3500-4000 and see how fast you're going when you get to the meaty part of the rev range in 1st and 2nd gears .

In the excitement wave to the cop or contractor in the plain white Territory with the dinky little radar dish on the roof .

Six cars a second they are claiming they can nail at any one time .

Whilst I agree with the above, there is also a factor of personal choice coupled with the requirements of the a car as outlined by the driver.

I am often frustrated when people who build engines with racing outlooks IE the use of large framed turbocharger'(s) complain about lag or as we have previously discussed the big kicker detrimental 'Transient response' as they obviously fail to comprehend the inherent compromise between driveability, comfort and optimum performance, unfortunately you really can't have your cake and eat it to.

Personally I do enjoy the performance of the larger paired turbochargers such as -5's, however I am extremely aware of the trade offs I am making in using these sized turbochargers and will be the first to relate that their are much better street combinations available.

Edited July 11, 2010 by Nee-san

[discopotato03]

Well in some ways I relate 26's in GTRs to RB20's in R32 GTSTs , turbo choice can improve the factory product or push the top end higher . I suppose having an RB25 in a RWD R32 does similar sorts of things to having an RB30 in a GTR as far as low down torque is concerned .

To each their own , its just than it can be frustrating to see people built exactly what they won't like and have to suffer it because they can't afford to do the job again .

I still have my 25T but went to an Evolution Lancer because on paper it has 3 Kw less and is 120 kilos lighter than a 32 GTR and my GSR6 is the heavy version . Approximately the same size brakes/wheels/tyres as a V Spec R32 and on paper makes its peak torque at from memory 3500 revs .

They are far easier to get user friendly gains out of than a GTR while still being acceptable as a road car .

If GTRs are your thing then go for it , just remember that they cost a lot of time and money and if you're trying to change the factory dynamic of what they are you may be painting yourself into a hellishly expensive courner .

Last time , they were the basis of a narrow focus Group A tarmac racer where low end power was of no consequence . This shows in the road going cars as well .

The Evos up to 6 were also factory homologation specials but the power delivery and handling attributes needed for rallying are very different to tarmac racing . They have to be light/nimble/agile and punchy to have any hope of being competitive . In my opinion what works for rally is MUCH closer to what works in a toned down road car because it isn't the constant high speed abilities of a tarmac racer that is usable on public roads .

I'll be honest , Godzilla and Nissan did great things to the automotive world in the early 90s but the death of turbos were always going to kill it . I get my fix from dusting off my 92 Bathurst video and watching it .

Hair dryers and AWD lived on in International Rally classes and the rule makers forced the manufacturers to develop engines that made strong mid range torque (650 Nm) from 2L with turbo restrictors . In registerable form the same dynamic works and I guess that's why Mitsy and Subaru have sold so many AWD turbo cars , far more that Nissan ever did .

A .

[Nee-san]

Well in some ways I relate 26's in GTRs to RB20's in R32 GTSTs , turbo choice can improve the factory product or push the top end higher . I suppose having an RB25 in a RWD R32 does similar sorts of things to having an RB30 in a GTR as far as low down torque is concerned .

To each their own , its just than it can be frustrating to see people built exactly what they won't like and have to suffer it because they can't afford to do the job again .

I still have my 25T but went to an Evolution Lancer because on paper it has 3 Kw less and is 120 kilos lighter than a 32 GTR and my GSR6 is the heavy version . Approximately the same size brakes/wheels/tyres as a V Spec R32 and on paper makes its peak torque at from memory 3500 revs .

They are far easier to get user friendly gains out of than a GTR while still being acceptable as a road car .

If GTRs are your thing then go for it , just remember that they cost a lot of time and money and if you're trying to change the factory dynamic of what they are you may be painting yourself into a hellishly expensive courner .

Last time , they were the basis of a narrow focus Group A tarmac racer where low end power was of no consequence . This shows in the road going cars as well .

The Evos up to 6 were also factory homologation specials but the power delivery and handling attributes needed for rallying are very different to tarmac racing . They have to be light/nimble/agile and punchy to have any hope of being competitive . In my opinion what works for rally is MUCH closer to what works in a toned down road car because it isn't the constant high speed abilities of a tarmac racer that is usable on public roads .

I'll be honest , Godzilla and Nissan did great things to the automotive world in the early 90s but the death of turbos were always going to kill it . I get my fix from dusting off my 92 Bathurst video and watching it .

Hair dryers and AWD lived on in International Rally classes and the rule makers forced the manufacturers to develop engines that made strong mid range torque (650 Nm) from 2L with turbo restrictors . In registerable form the same dynamic works and I guess that's why Mitsy and Subaru have sold so many AWD turbo cars , far more that Nissan ever did .

A .

At that bodyweight, they really do scream for more cubes... or less weight

Evo's have always been a very good package, especially when your talking upto moderate levels of modification, the 4g63 is an excellent engine and as a whole probably a nicer package then a GT-R when you take price into consideration.

That said, after you start spending the big cash money is when the GT-R really streaks ahead.

And yes, I agree it's sad seeing people spend money making their cars worse.

Your right, the On off on off, half throttle, WOT and fast changes in direction that personify rally is infinately closer to street driving then a lap at bathurst where the engine is living up in the danger zone as far as revs go for most of the lap.

And on a final note, I was very sad they didn't make the 370 Z a TT.. That would have been cool.

[DAS KAMU]

i have - 5's and i think there awesome

[Rolls]

I don't know why people don't just aim for 280kw that comes on as soon or even earlier than the standard turbos, it will make for a faster street car, full boost at 4500rpm just sounds awful, sure you might have an extra 80kw in the top end but you are losing more than that in the low/mid range making the car slower overall on the street, not to mention the transient response of using the larger turbos.

I would rather max a turbo out and have it fall over in the top end than go a size up and make more top end power. Response and low down power is where it is at.

[usmair]

I don't know why people don't just aim for 280kw that comes on as soon or even earlier than the standard turbos, it will make for a faster street car, full boost at 4500rpm just sounds awful, sure you might have an extra 80kw in the top end but you are losing more than that in the low/mid range making the car slower overall on the street, not to mention the transient response of using the larger turbos.

I would rather max a turbo out and have it fall over in the top end than go a size up and make more top end power. Response and low down power is where it is at.

yeh at the moment its awful because its a half arsed job... the original plan was to buy everything and do the mods all at once...

the turbos were replaced due to the originals letting go... which is what will most likely happen if you squeeze 280kw out of them...

once the exhaust is sorted it will spool much quicker...

[Harey]

I don't know why people don't just aim for 280kw that comes on as soon or even earlier than the standard turbos, it will make for a faster street car, full boost at 4500rpm just sounds awful, sure you might have an extra 80kw in the top end but you are losing more than that in the low/mid range making the car slower overall on the street, not to mention the transient response of using the larger turbos.

I would rather max a turbo out and have it fall over in the top end than go a size up and make more top end power. Response and low down power is where it is at.

Everyone is different and likes different things. Yes I agree that sounds quite practical for someone that likes power quick to find in any gear. Some people like the rush of no boost to full boost. Some people have autos, some have manuals, some are used on the track, some are used at the drag strip and some babied down to the shops.

I dont agree with "Response and low down power is where it is at", I think its a compromise between low down, mid range and top end power. If all you want is low down power and response then buy a V8!!! Obviously there is more to it. And the compromise you make depends on each individual driver, their setup and their intentions for the car.

Edited July 14, 2010 by Harey

[GT-R32]

Exactly. And unless the engine and turbos are totally unmateched, use the gears! That's what they're for. As long as you have a spread of solid average power from shift points the car is going to be fast if you know how to change gears.

My car with -5s makes 300+awkw (dyno depending) from 5 - 7+k RPM. It's making very decent boost from 3k RPM (that's 3rd gear at 60km/h) and over 200awkw from 4k RPM. The car is very quick in 3rd from 80km/h to very illegal speeds. First and second are geared so low the torque multiplier takes hold and it just hauls. I just don't get how that's perceived as unresponsive... It's making far, far more than a stock one makes at peak from 4 - 8000RPM. That's a fair spread of power for now, with scope for a lot more when I do cams, cam gears, more fuel and freer flowing exhaust.

It comes down to priorities.

[DAS KAMU]

Exactly. And unless the engine and turbos are totally unmateched, use the gears! That's what they're for. As long as you have a spread of solid average power from shift points the car is going to be fast if you know how to change gears.

My car with -5s makes 300+awkw (dyno depending) from 5 - 7+k RPM. It's making very decent boost from 3k RPM (that's 3rd gear at 60km/h) and over 200awkw from 4k RPM. The car is very quick in 3rd from 80km/h to very illegal speeds. First and second are geared so low the torque multiplier takes hold and it just hauls. I just don't get how that's perceived as unresponsive... It's making far, far more than a stock one makes at peak from 4 - 8000RPM. That's a fair spread of power for now, with scope for a lot more when I do cams, cam gears, more fuel and freer flowing exhaust.

It comes down to priorities.

just what i wanted to say

[Rolls]

As long as you have a spread of solid average power from shift points the car is going to be fast if you know how to change gears.

If you have a built motor that can handle the high rpms required for a big spread of power then yes I agree with you, I was more getting at power coming on after 4.5k and a redline of 7.5-8k which is barely 3k of usable power band. If it comes on at 3k though then sure, go for it, I don't doubt that it feels responsive.

[R.3.2.G.T.R]

I have GT-SS (aka -9).

They're fantastic turbos to have. I have 302.8rwkw @ 18.6psi (will need to put up the dyno sheet)

gimme gimme

[iplen]

Pair of -7s on the way, I have decided to stop reading suggestions etc about which way to go, for me it came down to 7/9, I spoke to GCG, said "I want 300awkw, without to much stress, but, will be used for street, and circuit etc, want a car that is responsive and will not being going chasing more later as it is not ALL about horsepower for me and this car" he said -7 all the way, so that was it. Initially they will go on with only mods being:

exhaust from dumps back

Apexi Pods

HKS Hard piping kit

HKS EBC was previously running upto 20psi (on ceramic turbos ) but will probably wind it down to 17-18...

Fuel pressure reg

When we know how that goes it will have run on the dyno with a Top Secret ECU that I scored, if that behaves it will stay on, eventually PFC as well as maybe some injectors.

Results will be posted.

-7 are on and running, only had 2 little blasts at 14psi, feels very similar to standard, not much noticeable lag so far, no extra noticeable power so far, will get a better idea soon