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Friday, July 07, 2017

How Do I Build a 500 Horsepower Skyline GT-R ? 600 Horsepower ? 700 Horsepower ? 800 Horsepower

R32 GT-R on the dyno. The emissions dyno, for California compliance. 
How do I build a 500, 600,700,800 horsepower Skyline GT-R?  The R32, R33 and R34 GT-R engine in these Skyline platforms have very minor differences from 1989-2002 There are some minor differences, a few different blocks, some different turbos and exhaust manifolds, but for 95% of the RB26 out there this information is all the same.

#1 The turbo makes the power
#2 The supporting modifications make it work and survive


Do those two statements make sense to you? The engine itself is just a big air pump for the turbocharger.  We have a hard time changing the engine characteristics without getting into the RB26 internals.  The more air the engine can push at the exhaust wheel, the more air the compressor side can ingest.

The bigger the inlet, the bigger the compressor wheel, the more air it will flow at a given RPM. The more it weighs, the harder it is to get it up to a certain RPM. Turbo sizing is a bit of an art and a science. You have to read into some of the compromise to achieve certain levels of performance.  If you aren't sure, then you go off past data. If you want to experiment, first check and see if anyone else has done it.  The current world in turbos for GT-R's, the popular route is a single turbo, from the OEM twins.  While we personally prefer the OEM look of under manifold twins, that look isn't for everyone.

Mostly stock early R34 with Apex'i Air filters.  Notice OEM all aluminum radiator

Plotting turbo data. Turbo by Garrett

For the equations below, we will divide BSFC by 60 to convert from hours to minutes.
To plot the compressor operating point, first calculate airflow:
  • Wa = Airflow actual(lb/min)
  • HP = Horsepower Target (flywheel)

  •  = Air/Fuel Ratio

  •  = Brake Specific Fuel Consumption (  ) ÷ 60 (to convert from hours to minutes)

11.5 A/F was picked as a generally safe ratio for gasoline
0.55 was picked as a middle of the range BSFC for a turbo car.
This figures are at the engine

Wa= 500 hp (at the engine)* 11.5(A/F) *0.55(BSFC)/60   = 53 lb/min

Wa= 600 hp * 11.5 * 0.55/60 = 63 lb/min

Wa= 700 hp * 11.5 * 0.55/60 = 73 lb/min

Wa=800 hp * 11.5 * 0.55/60 = 84 lb/min

Thus, a compressor map that has the capability of at least 53-84 pounds per minute of airflow capacity is a good starting point. 
Note that nowhere in this calculation did we enter any engine displacement or RPM numbers. This means that for any engine, in order to make 500 Hp, it needs to flow about 53 lb/min (this assumes that BSFC remains constant across all engine types).
Naturally, a smaller displacement engine will require more boost or higher engine speed to meet this target than a larger engine will. So how much boost pressure would be required?
Calculate that here.  You can use one or two compressors to meet the airflow requirements. There are also some exhaust housing, and exhaust sizes to be looked at in order to allow the compressor to reach the speeds it needs to ingest the air required to make the power.

Tons of turbochargers/Nissan Skyline dyno charts plotted. Singles, twins. Almost all older stuff

This chat shows an example of a car, turned for area under the curve vs outright power(white line). This car was a 2.8, with GT-RS turbos. Some headwork, and advanced on the intake side to help bring up the bottom. 
Above you can see how different the plots look for the white line, vs the blue line. Both are the same turbos. One is a 2.8 with lots of work and refinement. The other just had the same turbos slapped on it.  About 800 rpm response improvement.  Again these are the same turbos, HKS GT-RS or a Garrett GT2871 which are a large under manifold turbo.

How to build a 10 second R32 GT-R - single turbo Australia. 

Buy USA Legal R32 Skylines at! for Nissan Skyline GT-R and GT-R parts.

Supporting Mods
R32 GT-R Buyers Guide
First check all the basics. 
Next do all the maintenance. 
Read about some RB26 myths and truths

For each of the next supporting systems, we have to ask how you use the car. If you are one dyno pull chump, then you can probably make about anything survive. Don't be a Supra owner, don't throw that one dyno pull number just to try and impress your imaginary friends on the internet.  In real life its area under the curve that makes a nice street car. It is a car you will want to drive, vs an on/off switch. If you are actually serious about racing, you overbuild. If you live where its hot and humid, you pay extra attention to cooling. If you drag race, then drivetrain is always a concern.  If you road race or autocross, you work on the driver before any of this stuff.

Fuel system
DO NOT. DO NOT put a t in this line. You just added at least four more failure points. If you lose this line, your car will probably blow up.  I don't care what they did in Japan, I don't care what the instructions say. Use the back of the balance tube for anything you need to get a decent vacuum and boost reference. 

Horsepower. Just about everyone wants a 500, or 600, or 1000 hp car. Assuming everything else with handle it, let's just focus on the fueling requirements of the engine.

RB26, we have 6 injectors. The factory injectors are low impedance, and they have a resistor box in the circuit. This is important, as most modern injectors are high impedance, and can eliminate the resistor box. HOWEVER, if you eliminate the resistor box, with a normal ECU, and low impedence injectors, you will probably burn out the injector drivers. So make sure what you have, before you go eliminating parts.

A fairly safe rule of thumb on a 6 cylinder engine on gasoline is about 1 hp per cc at the engine. So a stock 440 cc(485 cc at 43 psi) injector is enough for about 440 hp (485 hp) at the engine on an RB26. In real life you can push it harder, or see less depending on the condition of the entire fuel system.
NZ EFI 1000 cc drop in high impedance injectors. 

Tilton carbon/carbon triple plate clutch. This is 1/2 the weight of a stock clutch, and will support over 1200 ft/lbs. 

GT-R kill clutches. All wheel drive, RPM put a hurt on a clutch. Above about 500 hp most twin plate clutches start to have issues. Again, all how you use the car. Twins aren't bad to drive, triples are harder to drive.  Sprung hub help the drivetrain to survive, but once you get up to a triple most are solid center.

There are two clutch styles, Push and Pull. Later cars are pull, but almost all aftermarket are push. Know what you have. It is possible to convert, but it is a pain in the ass.

Clutch Push vs Pull.

Nismo Coppermix are popular current clutches, but as a twin above 500hp they start to get iffy for drag racing.   Exedy/Daiken make the clutches for NISMO and they have some good options.

Clutch Weights

Ignition System
OEM coils missing a spring. FOUND YOUR MISFIRE
Ignition and the ignition system. When you have a misfire, on an engine, you effectively are losing the horsepower for that cylinder, wasting fuel, and potentially causing damage to the engine.

There are two types of coils, ignition systems on a stock RB26DETT, the R32/R33, and the R34. The coils on the R32/R33 are the same, both have an external igniter. The R34 have a built in igniter (same as series 2 RB25).

We have heard that the stock coil output is 45kV. However we haven't seen any confirmation on that number. A coil on plug setup like an RB26 is superior to a normal coil/distributor cap, as each coil has more time to charge and discharge, cool off, vs a single coil setup. It also allows direct control of coil dwell time, and firing time.

You can take a new condition RB26 ignition system, with a voltage boost, and a good spark plug to up over 1000 hp. If you can't you have something in the system that needs troubleshooting.

More ignition system information, troubleshooting, and coil replacements.


Getrag V160 in the R34 GT-R race car. 
There were two main transmissions used in the Nissan Skyline GT-R's from 1989-2002. The R32 and R33 used a 5 speed transmission from Nissan(FS5R30A), and the R34 GT-R used a 6 speed transmission from Getrag(V160). The FS5R30A is very similar to the 300ZX transmission internally. The Getrag is similar to the transmission used in the MK IV Toyota Supra. The input shaft and main shaft are unique to the GT-R on both transmissions, the rest of the internal parts are interchangeable.

All wheel drive cars are hard, hard, hard on the transmission. When the wheels don't slip, the hard parts break. Third gear is a big one in R32/R33. Bang third gear hard, and it will let go. Some people say the late R33 box is stronger, but I have tried them all, and broken them all. Once, twice in a week in a 500 hp R32 with a nasty clutch(unsprung HKS/Tilton). You want a sprung hub, you want to run Redline Shockproof Heavy gear oil in most trans(not the V160).

More transmission information
How to install a 6 speed Getrag transmission in an R32/R33

ARC twin entry intercooler
The stock intercooler on a Nissan Skyline isn't bad as far as factory parts go. They are 3 inch inlet and outlet. The OEM core is 24 inches x 10 3/4 inches x 2 1/2 inches. They are mounted in a great spot. Try and make sure they have good ducting for air through the core. Through is the key. Air is lazy takes the path of least resistance. If air can pass over, around or under the core, it will.  On the R34 race car, it ran an OEM intercooler up to and beyond 580 whp.

There is a sweet spot for intercooler size The larger it is, the more airflow required to fill it up before air goes into the engine. The larger it is, the more likely it blocks cooling airflow to the radiator/engine.  Since the intercooler is a heat sink, it needs to have the capacity to cool the heated compressed air out of the turbocharger/turbochargers. Cooler air is better.  Don't go overboard.


OEM radiators are OEM. They are plastic top.  They will support stock horsepower, but once you start making power, you need to look at them. Ducting is key. Make air flow through the core, not around it.   The shroud is very important. It helps keep the car cool at low speed, probably when you need it most on a street car. There are lots of manufacturers out there. Koyo are a good brand that has been around many years. We have run Ron Davis, and C&R on proper builds. Electric fans and OEM clutch fans. The OEM fans do start to crack, so inspect them. The R34 clutch fan is a little different design than the R32. GK Tech has a replacement fan.  When asking about the clutch fan vs OEM fan for the World Challenge R34, our Falken/NISMO contacts said to use the OEM clutch fan.  So we have.

Oil coolers and oil cooling. On an RB26DETT, you have a lot of factors that contribute to oil temperature. It is honestly near an oil cooled engine. The higher you rev it, the more temperature you add. At a point you can't cool the oil enough, and it breaks down. When it breaks down enough, you kill an engine. An RB26 has a long crankshaft with 7 main bearings. Each bearing is adding lots of heat at high rpm. More oil cooler and oil cooling information. 


Slippery slope with the engine. You can make 500 plus horsepower on the stock engine, assuming its brand new and never was abused. Since you probably didn't own this car/engine from new, you really don't know the overall condition.   The lean hole is #6. If you think the motor is hurt, aka blowing smoke, popping the dipstick out under boost, check #6 first. It probably broke a ring land.  If it sounds like the top end is making noise, about 90% of the time it has spun a rod bearing. Watch oiling and oil pressure. If you have oil issues, you normally spin #2 rod bearing first.

Engine rebuild and reinforcement video

Engine rebuild recommendations. 

Cam Timing Adjustment, and camshaft options for an RB26dett

RB30 , RB31, RB32. When 2568 cc, just isn't getting it done. 

OEM 296 x 32 rotor and 4 piston caliper on a BL0 R32 GT-R. 

You have to be able to stop, if you plan on running the power more than once. We are big fans of tuning the stock parts vs just slapping some Chinese knock off, Revving High,  6 piston junk caliper on the car. The truth about brakes, is the tires stop the car. The best brakes in the world with the cheapest tires, still won't stop that well. Use a good tire, check wear. Rotate tires, run them hard, put them away wet, but just maintain them.

A track day requires a different setup than a street car. The hardest part is a lot of guys(me included) want a dual purpose setup. Normally with brakes, if it works great at the track, it might not be as good on the street, and vice versa.

Heat is the enemy of the braking system,well excessive heat. Every brake pad, every rotor, every brake fluid is going to have a range that it works well within. When you run outside this range, things go down hill and wear out quickly. I have written a lot about the brakes on the R35, and similar things apply to the R32, R33, and R34. The R32 Vspec, R33, and R34 all had Brembo 4 piston front, and 2 piston rear brakes.
Brake rotor weight

Adjuster on Ohlins DFV suspension on an R32 GT-R
Suspension. There are lot of parts to suspension.  Some people use the term to only refer to the coil overs/shocks, but there are also suspension arms that encompass the term.  Most Japanese brand coil  overs are over sprung and underdamped. What this means is the springs are really stiff, and the control of the spring is not where it should be.  While that setup may be fine on very smooth roads, or very smooth tracks, here in the US, we generally have neither.

In order for you to be able to control the car, the tires have to maintain contact with the road/track surface. If the car is so stiff that the tire is bouncing up and down, and not contacting the road, you will not have control.  There are many reasons not to over lower a car, or to make it too stiff.  Stiffness does not equate fast or good handling.  We see all kinds of chinese branded coil over crap sold to unknowing young buyers. When you are young you might be able to live with shitty suspension, but as you get older, and  have a chance to try out cars with hundreds of setups, you will probably much prefer a real coil over, vs some eBay crap.

As far as brands go, we like Ohlins. There are different levels of Ohlins, the newest are the DFV, or dual flow valve setups.     Ohlins does a good job of matching spring to damping.

Ride Height : Don't go too low. The suspension has to be able to compress to work and control the tire
Camber : The reason for camber, is not for you to fit the widest tire possible. Camber flattens out the tire as you are cornering. Too much camber negatively effects braking.
Toe : You have 10 of them. Or rather it is the direction the tire is pointing. Toe in, or toe out. Toe in make a car more stable, toe out makes it a little less stable. Toe being off is the biggest wear of a tire.
Caster : Shopping carts have casters. In a car it is self centering of the wheel, and steering effort related.

As far as adjustable parts go, if you don't know what they do, and how they interact with how the car handles, you might not want to mess with them. There are plenty of ways to adjust how a car handles, based on how you drive, and tire pressures, but lots of people want every piece of adjustable suspension component they can get, then leave it all stock settings. Don't be that guy.

Suspension and Alignment Settings : R32, R33, R34 GT-R
Suspension Parts : Nissan Skyline GT-R
R32 GT-R Chassis Bracing
MotoIQ : The Ultimate Guide to Suspension and Handling
Wheel Hop

Ohlins Flag R as ran on the R34 World Challenge car. 
An example of a shock being unable to control a tire. How can this person not notice this?

Tires and Wheels

Volk TE37SL 18 x 9.5 +22

You can't put the power to the ground without the right tire. While you shouldn't chose a high heel to rock climb, you also shouldn't chose a tire that doesn't fit what you are doing.

What wheels fit my R32 GT-R? 
Can I run different sized tires on my Skyline GT-R?
16 inch tire options for OEM R32 GT-R Wheels

BBS LM Wheels . 18 x 10 + 20 offset. 265 width tire


Anonymous said...

Hi Sean,
Since you do not recommend the T fitting near the FPR, do have a pic or guide on where to properly put it? Actually mine is like that... and yes it's already like that from Japan I think. ��

Sean Morris said...

The next line says right there - " Use the back of the balance tube for anything you need to get a decent vacuum and boost reference. "

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