Theoretical Power Numbers

[Darrel]

Hi gents, sincerely asking you guys the theoretical or actual power figures expected from the setup below:

HKS Y pipes & 80mm cat back, Sard (denso) 720cc injectors, DW300 pump, R35 MAFs, Twin HKS 2530's (stock headers), Trust intercooler, stock BOV, stock intake plenum & TB's, N1 oil pump, MLS head gasket, forged pistons, poncam B's, Power FC, pump RON97, nismo coppermix twin plate, 18's on 265 rubber.

So I've pretty much listed all that matters with regards to making and putting the power down. Asking as I may or may not be getting the full potential of my setup (bottom end was running 600rwhp on a different car). I have done numerous Dyno sessions with slightly different setups but more or less the same outcome which leads me to conclude (reluctantly) the setup is maxed out. Will share graphs but would like you to share your input first for better effect. Thanks in advance, guys!

[GTSBoy]

720cc injectors can only support about 720 engine HP. Maybe a little bit more. 600rwHP is, um, a plenty big chunk of that number. Probably running to the top of your fuel supply.

[Darrel]

@GTSBoythanks for replying. That's realistic and I always believed in the injector-hp rule of thumb. I am however making way less than that 😕 My guestimate/goal for the setup is a reliable 500rwhp, R33 gtr, seems realistic enough doesn't it?

[Murray_Calavera]

26 minutes ago, Darrel said:

500rwhp, R33 gtr, seems realistic enough doesn't it

Sounds reasonable to me. 

Do you know what your injector duty cycle is? I guess everyone has their own personal limit as to how high they want to flirt with 100% duty cycle, but who knows what your tuners limit is. Maybe they like to cap it at 80%? Now your injector CC to HP conversion has a 20% hair cut on it, then through drivetrain losses, yeah 500rwhp seems ok to me. 

If you plan to spend on your GTR, modern injectors and a modern ECU will go a long way! 

[GTSBoy]

Yeah, so I think that is the point. If you presume a 25% lower reading on a chassis dyno than what the engine is making, then the most you would see from a 720HP engine is ~550wHP. "Lose" a little more because AWD dyno and the number will be lower. Call a hub dyno "wheel HP" and you should see higher numbers. But the horses would be a different size.

And as Murray says above - an imposed 90% DC limit drops 550 down to 500 straight away. 80% takes you down to ~450.

[Darrel]

@Murray_Calavera I forget but it's well within the duty cycle limits, my tuner is probably the only guy I trust locally to tune, definitely not the best but with his knowledge and experience, definitely the best here IMHO. He said it's the most he could get out of it on the last session (cam change) and increasing the boost wouldn't give much more gains.

Yeah, definitely plan on upgrading to Link G4X or similar but I'd like to max out my setup first which I believe many have done so around 500hp.

[Darrel]

26 minutes ago, GTSBoy said:

Yeah, so I think that is the point. If you presume a 25% lower reading on a chassis dyno than what the engine is making, then the most you would see from a 720HP engine is ~550wHP. "Lose" a little more because AWD dyno and the number will be lower. Call a hub dyno "wheel HP" and you should see higher numbers. But the horses would be a different size.

And as Murray says above - an imposed 90% DC limit drops 550 down to 500 straight away. 80% takes you down to ~450.

That last number you quoted is right about where I'm stuck, pretty spot on. Now let me share some of my Dyno results. Stock cams, stock fuel pump, stock MAFs, stock injectors, same exhaust and everything else oh yeah I forgot to add tomei FPR, intake cam advanced 2 notches, exhaust retarded 1 notch. Let's call this Dyno 01.

 

Edited May 15, 2024 by Darrel

[Butters]

2530 is a 250-300whp turbo on 98, So  x 2 , take some tax as you have two and that is your answer.

You tend to have to have the boost pretty high in twin setup, which is not great for U98 as heat kicks in quick.

 

As above though, more injector is going to get you more but you need to be realistic with a older twin setup on 98 fuel.

Cool as heck but not the best way to make power these days.

[Darrel]

Hi @Butters , thanks for your reply. Pump 97 BTW but yeah, I get that old tech is what it is and can't compare to modern stuff but I still believe 500 is achievable, even with these smallish twins. Their effective limit is around what, 24 psi? Intend to go single one day but then again, I'm not chasing big power and might not be worth the investment. Just wondering what if any factors are limiting my setup after a few changes.

Let's call this Dyno 02. This is after R35 MAFs, 720cc injectors, DW300 FP, HKS step 2 264/264 cams.

[Murray_Calavera]

@Darrel Can you get pump e85 where you are? If you want to max out those turbos, e85 + bigger modern injectors will be the easiest way to get you there. 

[Darrel]

@Murray_Calavera nah, not available yet, they're gearing up for it but won't be available for a few years. So you reckon fuel is the main issue? When this bottom did over 600rwhp it was running big single, twin Z32 MAFs and believe it or not, e manage blue, an old school piggyback 😅 not really a fair comparison but I guess it shows how a big single differs to smallish twins. 

 

[Murray_Calavera]

@Darrel It's so tempting to say e85 is borderline magic. It cools the intake charge, so if you're flirting with the edge of the turbos compressor map it helps dramatically cool down the hot air the turbos are pumping. It is very resistant to detonation so you can crank the timing, I don't really want to say you won't be knock limited anymore.... but you probably wont be knock limited anymore lol. I wouldn't be surprised if you made 20% more power swapping to e85 (provided you have the fuel system to support them, bigger injectors maybe bigger pump etc). 

[Darrel]

@Murray_Calavera yeah, I guessed as much, cooler temps, more boost, less knock, more timing, hello power. Unfortunately not quite within reach ATM, could upgrade my whole fuel system to support but still wouldn't have E85 to run it 😂 

Anyway, I changed cams again, 260/260 poncam B and everything else the same except an EBC upgrade.

Now I must say I was quite disappointed with the result as it was like running stock cams (didn't try to dial them in as they're supposed to be optimum already) but after awhile I suspected my new EBC was underperforming not to mention difficult to use. I recently swapped back my old EBC and it drives much better now, boost comes on sooner, more stable, no spikes etc, feels all quicker and faster than with stock cams.

Planning to fiddle with the cam gears and see what happens but maybe skip the Dyno as I intend to revert to the HKS cams cos they really made the car come alive; low and mid end was unbelievable and it just wanted to rev to the moon, finally knew what people were raving about, RB26 really loves revs.

Anyway, Dyno 03 is quite disappointing, in Dyno 02 although peak power was less and trailed off at the top, the low and mid end improvement more than made up for it.

[Butters]

Cams are not needed at this power level, they will create lag. The cam gears are a good idea though.

[Darrel]

@Butters I can't tell you why but the bigger HKS step 2 cams improved low and mid end immensely. Turbos started spooling about 1k RPM less than before and the idle/vacuum was rock solid, it was an absolute thrill to drive, 3rd gear pulls hit 180kmh where previously only managed 160.

Conversely, the milder poncoms in there now have a funky idle making it harder to get off the line, drives poorly in lower revs, laggy and makes less power/torque throughout. Feels better after I swapped the EBC but unless I put it on the Dyno again, I can't say how much better.

[Predator1]

199.69hp