Tuned vs Cams and Headwork 7M

[toyotanos]

Rob (92NSX) and I just dyno'd at a dyno day today and guess what- we made the EXACT SAME POWER! All pulls were on a Dynojet RWD dyno.

Rob's mods are as follows -8an oil pick up hose, new oil pump shimmed 7mm, .040 over probes, eagle rods, balanced, HKS 1.2m MHG, BC 1mm over sized valves, BBC springs, BC 272 cams, Aeromotive A1000 AFPR, Lexus AFM, RX7 550's, P & P, Gates Racing T-belt, AEM cam gears, FFIM, fake SSQV bov, FMIC, K&N filter, 3" DP and test pipe, HKS super turbo exh., profec A EBC, BOSS Sr. - P-trim 61mm, GTS housing triple ceramic ball bearing - polished turbo, thermostatic - full flow - remote oiling system Stock clutch and PP.
15lbs of boost gave him 417.41 HP and 382.81 TQ.
ALL ON THE OEM/***NONPIGGYBACKED ECU The only tuning device was fuel pressure.

My car, on the other hand...
Put down 417.41HP and 391.44 tq
Has a fully built 7M, with pretty much the same mods, but no cams, or headwork. Almost everything is the same otherwise. I have a long runner intake mani with the stock TB, AEM EMS, 2JZ-GE ignition system, sequential injection, 720 injectors, and a mk4 TT fuel pump.

Here;s the dyno charts: robs's runs, most at 15ish PSI

My dyno runs, most at 18ish PSI

I know the main difference was Rob's cams, but DAMN! I wanted to at least do 450 vs the dyno dynamics I tuned on...

 

[IJ.]

What Turbos/Boost on both cars Steve?

 

[toyotanos]

LIPP Boss CT461 61mm, p-trim exhaust .83 housing. 15lbs for Rob, 17/18 for me.

Both are Triple ball bearing

 

[IJ.]

Really interesting Data set then
(look how much fatter Rob's midrange is)

Why are you pissed?

 

[toyotanos]

I wanted to be running more power than good 'ol Rob. He's running stock TCCS with no adjustments (mo piggybacks at all), I'm running a fully adjustable AEM that just got tuned.
Not so much pissed off, more surprised that he did so much better than I was expecting. He's sitting here next to me by the way- no hating on Rob.

 

[IJ.]

Tuned right your car should be nicer to drive and get better economy but at WOT headwork and cams are always going to be ahead

 

[toyotanos]

lol, so maybe a title change is in order- tuned vs cams and headwork 7M or something on par with that... Something to show to difference between the two?

 

[IJ.]

No probs done!

 

[toyotanos]

Thanks Ian- Rob was floored when he saw above 400 on the chart... and even more so when he saw that we had done the same numbers!

Reason I posted it is I think a lot of people would enjoy/get value in seeing these charts compared to each other. Our cars are VERY similar in most aspects, but the few differences that exist make them feel like completely different beasts to drive.
My turbo comes online quick and hits really hard, where his seems just kind of lazy but still puts the big numbers down.

 

[IJ.]

Yeah that's the midrange I was talking about, my 7M made stupid numbers from about 3500 onwards and I always put that down to the Cams and Headwork, Crisp verified it when he bought my Head and bolted it to his stock engine.

 

[toyotanos]

So how big were your cams? Rob's got the BC 272's and expects to make power well into 7000+ rpm's eventually. So now I'm wondering of some 258 or 264's might not be a bad idea. I don't think I can spin that fast (7m crank) but maybe 6750? I've had limited luck with finding info on good redline data.

 

[IJ.]

280's

 

[92nsx]

WHOO!!! Yes I am still stoked about today. Now to change the plugs, smaller gap (there at .32 ish IIRC) and get some more FUEL in the car! I have a feeling 044 pump and a small piggy back will be coming in the mail for me shortly here Once i get the A/R good ( and at least SOME fuel at idle) it should be more enjoyable. Idle right now is off the charts (way over 18!! )

One interesting thing, at 16 or more psi I hit fuel cut!!!! You should have seen the guys face that was doing the pulls on the dyno when she hit fuel cut. I think he went straight to the bath room to check his pants. He said he has never felt that much of an aggressive fuel cut.

Speaking of what little "tuning" we did this is it. Turned fuel pressure down from 35 to 30 psi. Then the owner was wondering what was happening at 4K rpm's so I explained or Steve did, how the fuel pump switches from 6 volts to 12 volts at 4K. So after that we tried a pull at 6 volts and WOW the power came on way faster/quicker at lower rpms. IIRC it was something like 370+hp around 4K (+ or -) but shortly after we REALLY ran out of fuel.

Then we hot wired it for 12V. and bam, better A/R's and the #'s showing are them on the graph.

Even with him shut down the pulls at 6500 rpm's (due to running out of fuel) the hp #'s wear still climbing. This engine wants to be spun higher! Fuel cut it at 6800 ish on my oem TCCS meaning if the engine is the original one it should have the 6m crank. But knowing how easily these 7m's blow it could have been swapped some time in it's 18 year life, before I owned it. Now I REALLY wish I would have check what crank I have in my engine when I sent it out to get built :cry:

Well it's late for me so im headed off to bed. Steve feel free to fix any miss info or add in what I forgot. Long day for me so Im sure I forgot/messed up something.

 

[thedave925]

Great info, especially the notable difference at the fuel pump voltage change.
I've known ppl that did the 550/lex combo on stock setups and wondered how the piston got melted.

I'm confused about one part though.
You're planning on a higher volume/pressure fuel pump for top end but you currently have the fuel pressure turned down to lean out a tad for leaner a/r, so it's theoretically barely idling (would be a high idle if carbed).
How snappy is the throttle off idle, and what is your base timing?

 

[toyotanos]

We actually did a couple things by reducing the fuel pressure- we made the idle crappier(bad), but we also reduced the load on the fuel pump above 5000 RPM which keeps the pump from getting overloaded and running the engine lean..
Ideally we would add fuel pressure to make sure we didn't get lean, but as of right now, Rob has ZERO piggybacks on the car and is out of pump capacity. As such, it is barely idling and often dies.
Everything else on the vehicle is factory settings- the timing is set just as it should be out of the TSRM.

 

[TurboStreetCar]

Strange is with the cams the torque peaks at about 4750 and drops off. Where as the stock cams torque peak at about 5200. Almost seems like the cams hurt the motor more then they helped. Its making the same power on 3 less PSI but the curve looks off. Maybe the cams need to be tuned/degreed in on a dyno?

 

[thedave925]

Toyotanos:
That's a good thought on the pump, Flow>Pressure. Running the 550/lex usually is $$Rich$$ at idle lol
He done well with no management. You both made great power for 84*f
On your chart the air fuel ratio is omitted but i'm sure looks better than Robs lol
Do you have an EGT gauge?

Nosechunks:
Factor in to Rob's chart that the Hp/Tq graduation scale is different from Toyotanos

 

[toyotanos]

Yeah, his cams are likely hurting his idle A/F ratio the most- it's never idled well with those 272's.

I really wish that I had brought my laptop and done a log of the pulls, but it was dead But no, I have no EGT gauge.

 

[TurboStreetCar]

Nosechunks:
Factor in to Rob's chart that the Hp/Tq graduation scale is different from Toyotanos

I noticed that and when you look at both charts the difference is the peaks. The 272 cams have a lower peak torque then the stock cams. Otherwise the torque curves are almost the same. Should have made a pull at the same boost between the cars.

 

[toyotanos]

^^ That's a great idea! Alas, for it to be accurate, we would need to do both cars again on the same day. Perhaps another dyno day will pop up soonish...