×

Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Nissan SR Brainstorming: With Set Turbo, Cylinder Head, Etc, How Can We Maximize Potential?

General Tuning Discussion

Forum Posts

Courses

Blog

Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads

Author
511 Views

So I have a project S13 with an SR20DET with some already defined parts I'd like to utilize, so I wanted to brainstorm how could I maximize the potential with what I have to work with. Please be as technical as you'd like. The more technical, the more I learn! I have some pre-conceived notions, but I am by no means an expert. So looking for a good discussion here!

Use Case for Car: This car will be used to get me seat time until my time attack car is ready in how ever many years from now... So it needs to ultimately be as reliable as possible, but still perform as well as it can. I plan to attend multiple grass roots events all around motorsports (drifting, drag racing, hill climbs, HPDE track days, etc), just to get as much fun out of it as possible, but for the engine, a road racing power band is key.

Parts I have on hand that I'd like to utilize: (Yes, I know some are now "old school", I've had some of these parts for over 15 years...)

* Greddy Intake Manifold suited for SR16VE N1 Throttle Body (and accompanying throttle body)

* Radium Fuel Rail & Dampener with ID1300cc injectors

* Full-Race twin scroll manifold with downpipe & internally gated EFR7163

* S13 SR20DET Cylinder Head due to manifolds

* Supertech +.5mm Valves for both Int/Exh

* WPC Treated Tomei 260 Solid Lifter Cams (Japan Market) & Lifters

* Supertech Valve Guides

Brainstorm: Now, I currently have a 9:1 DET bottom end with rods/pistons/ARP hardware that's been incredibly reliable. I plan to re-ring and re-bearing for good measure (has 14k very hard miles at +400whp since being put together). I also have a SR16VE crank sitting around. I've had a lot of thoughts of the CFM flow vs velocity for the S13 DET cylinder head running around in my head, and know that this is a choke point. My old S13 head I have since sold off unfortunately I was able to get 240 CFM at 12mm lift on the intake side (mild port work), but that's not stellar compared to say a stock P11 head which was 260 CFM on the same bench at the same lift. My power band was great with the 260duration/12mm lift cams, but it started to really fall off after 8k RPM with a GT3071R twin scroll I used to run. I'm afraid the EFR7163 will have similar issues. So would slowing down piston speed by going to an SR16 crank allow for better cylinder fill due to the CFM limitations of the DET head? I'm also ultimately interested in improving rod ratio to increase reliability by reducing loading into the walls, but was originally going to do the H22 rod adjust wrist pin location method to do so. Obviously running an SR16 crank would move the ratio considerably higher. The DET head has good velocity in the ports due to the angle, length, and throat reduction, but at the sacrifice of flow. I'm of course overthinking this, but I figured it could be an interesting thought exercise.

I am of course open to other thoughts on how to maximize performance with the restrictions above. I plan to run standard high octane fuel with this setup by the way. ECU choice is undefined at the moment.

No specifics, just some general comments.

If you're looking at doing pretty much whatever's going - and I agree with that attitude, they're fun and you learn a lot more - a "road race" engine may not be the best as some of those will be faster with a broader operating range and spool response time.

If you're using a different head, with the same cam's, you may find they have a different power delivery - possibly to the point of losing at both ends compared to a less aggressive selection. Either way, if you haven't done so, try experimenting with base timing (you should have some idea how much you can swing it, either way, from the V2P clearance checking) in, say, 2 degree steps.

Don't get hung up on how high you can run the engine as it's the actual power band that's important - and the area under the curve. If possible, within the mechanical limits, the engine is able to turn a bit beyond the crossover for the next gear, it may be faster overall if you don't have to slip in an additional up/down gearchange to avoid a limiter. But by the same count, don't get hung up on running to the limiter - it may be quicker to change earlier in some gears. Heck, the current turbo' era F1 cars were initially limited to 15k rpm, but their actual change points were closer to 12k because of the engines' characteristics.

Look at what you have, consider possible weaknesses. Have you checked the charge cooler pressure drop, the routing and the pressure drop, the airflow path through the charge cooler and the charge temperature drop across it. Are you using thermal barriers - paints/coatings, blankets and/or wraps, phenolic or other insulating spacer between the inlet and head? What about the exhaust manifold design - I've seen some very well thought out ones and some terrible ones.

Have a good think about the tuning - there are a LOT of people who should know better who will run timing significantly retarded from what the engine actually wants and then, further compromise it, by running very rich to be 'safe' - these can have the dual problem of late, slower combustion continuing into the exhaust cycle which elevates turbine temperatures which they try and counter by further increasing the fuel. Get them both right and you're going to be applying more energy to the crank and less to burning up your turbine.

Again, don't get hung up on the engine - give some serious thought to the transmission - more specifically the rpm drops through the gears, and the final drive for the best compromise between acc'n for sprints and top end for fast road courses. As the car's an IRS RWD, you may wish to have a couple of diff' assemblies you can swap over - a shorter locked/spool for sprints and a longer LSD for normal road and track driving.

A spare set of lightweight wheels and sticky tyres can make a huge difference compared to road tyres and will last a lot longer for a net saving. What have you done about brakes - pads alone (with good fresh fluid) can make a big difference, the problem being different events may have rather different needs - sprints/hill climbs need good cold performance and road courses good high temperature performance - but there are some very good materials on the market that work well at both ends, but $$$

What kind of oiling system do you have on this SR20 to want to be spinning it much over 8,000rpm? SR20VE pumps with billet gears are the only internal pumps I would consider using up there on a circuit with a good baffled lower pan.

Otherwise the engine mechanicals sound more than sufficient, just make sure the engine has quality oil, coolant and charge air heat exchangers and it should be more than reliable.

I agree with Gord that a lot of time and performance can be made up with a quality gear box, either a h pattern dog box or sequential with shift cut will give dramatic performance increases and it will be easier to keep your combination in the meat of your powerband.

Making sure brakes and suspension are up to the task, and whether their will be more gains to be had from upgrades here. A key thing to seat time is being able to do laps, so along with the heat exchangers, having brakes and suspension dampers that don't overheat allowing you to put a few laps together at once are great for your seat time.

The other thing I would really recommend is either via your selected ecu, or another logging device set the car up with GPS, brake and steering angle sensors, and use it for development and driver analysis. Getting into the routine of learning where your gaining and losing time, and in your seat time car will pay dividends when you move up into your time attack car.

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?