What's the Rev limit with a built motor?
 

I'm running a low-compression forged setup and wondering how high the rev limit can be raised with cams and heavier springs? Will Technosquare change the rev limiter only? If so, what do they charge for that single programming change? Thanks for any advice.

Bruce

i imagine they'll charge the full price for just that one change -- try having your idle raised... yup, same full price... ridiculous...

i imagine you could probably hit 7400rpm if you wanted to, but i'm just going to stick to my 7100 (anything higher and i would just wait longer to shift, so i want to make sure the engine is bulletproof :p)

technosquare does have the L-spec tune or whatever they call it where they don't mess with mapping at all and charge like 399 rather than 599

Machupo-
7100 is the number I keep seeing. I wasn't sure if they just didn't make power above that number or if it was a design limit.
002-M-P
I hadn't heard if they'd just change one piece of programming at a minimal fee, or if you have to pick from a pre-determined menu.

That limit is pretty close to the max limit of the stock internals with the rod ratio the motor has. Anything more I think would cause valvetrain and possible rod breakage. With a well balanced crank, rods, pistons, ecu, etc...and a better valvetrain you MIGHT be able to see 8500-9000 rpm's :cool:

I suppose you could do 8500-9000 rpm's a few times before the engine blows up.....

i might (and i stress MIGHT) bump mine to 7400 in the near future as the forged engine just went in along with the tomei 268's... the only reason though is because i imagine cams with that big a duration continue to make power above 7.1k... dynos will tell the tale :)

that being said, there is no way i'm going to 8k... not my cup o' tea (and i just spent waaay to much to simply blow up the pretty new engine :D)

Machupo-
That's in line with what I was thinking. I'll know more after my cams and springs are installed and we see where it tails off. I couldn't remember reading if anybody had raised the limit any higher.

If i'm not mistaken I think Rob can raise it to 7200 with the software he has. I believe thats where we are going to take mine.

Bruce-
I may need more because of all the extra weight I'm carrying.(the roadster, not me) Have you seen the "counter-weights" in the roadster? Off topic: has anybody ever posted a link to that car magazine article where they made a car faster by removing all the "extra" crap? It was pretty amazing.

lol, that's like my old shitbox volvo... it had 15kg iron weights inside each of the framerails to reduce vibrations... 10 minutes, a ratchet and a coat hanger later, it was riding just a bit higher in the front :p

The L-Spec replace is actually $349, and it raises the rev limit, eliminates the speed limit, and claims to improve TB opening response.

7100 seems to be a comfortable limit with the built motors. You will find they usually stop making power beyond 7000rpm, so unless you have a specific need for it, a higher rev limit will not get you more power.

Inertial loads on the road increase exponentially as RPM's rise....so what may appear to be a small increase, will in fact be a massive increase in inertial load.

Our ignition system also has RPM limits. I really dont know if our factory coils have the recycle time to drive an engine at 8000r-9000rppm and beyond without misfiring like crazy.

And lastly, as mentioned, the bore and stroke of the VQ do not lend themselves to very high speed operation. Possible, but you are fighting against the laws of physics. This is one of the reasons that the JGTC teams elected to use the VQ30 block...with its shorter stroke, and higher revving potential.

my rev limiter was set at 7500 rpms when we tuned it....im on stock internals stock valvetrain.....it has held up till this day, bouncing off the rev limiter, running it at the track reving that high, and just about all the hell i put my motor through on a day to day basis....i pushed this car farther than most people push rentals cars :D and its still together....someones gotta step up and test it out :p

Ben Y

i dunno, Ben, did i ever tell you about that neon i rented out in San Fran? driving past Shaq's house (this was in 2000) at 60mph up the mountain is pretty fun, but not as much fun as manu-shifting an auto when you're pretending to rally race up said mountains :D

The cylinder head layout is indentical to the 2JZGTE and 3SGTE with a completely shimless lifter design. Its the same layout found in crotch rockets. The inherent design of the V6 engine leaves it with an excellent rod-stroke ratio. You want to use high quality upgraded cylinder head components, especially the valve springs. Notice the JWT valvespring seat pressure is within factory spec... I would use the Ferrea everything if you plan to rev high. The ignition system is ready to go. Once we are done with my intake manifold I am hoping to have reason to rev it to around 8500rpm. I accidently hit over 9000 once on my built engine. I think the intake manifold is going to be hold you all back from making good power so high, even with cams. The ability to tune cam timing should would help.

running the higher rpm limiter, will this help with 1/4 mile and 1/8th mile times. seeing as you will be able to go further without shifting. probably a stupid question :) , but how much better times would you get , thanks.

That is not accurate. VQ35 is not an highspeed piston engine. It has a relatively short stroke and in JGTC 300, Formula renault, and grandam cup cars it revs without much difficuilty in the 8000rpm - 9000rpm range. The VQ35 is not simply a stroked VQ30 (there is only a 8mm stroke difference between the 2). I recall reading the reason why GT500 used VQ30, and it had nothing(not directly anyway) to do with the shorter stroke.

VQ35DE(350z) - 81 mm
RB26DETT(GTR) - 74 mm
F20C (s2000) - 84 mm
C32B (NSX) - 78 mm
S54 (M3) - 91 mm

and

F430 - 81 mm stroke

properly "built" VQ35 could rev like a mother****er... stroke is not an issue.

you are limited to: the bottom end 2. the valvetrain.

car is coil on plug...I bet you it could fire up to ~8500 without incident, maybe even higher. I run an Electromotive on my Datsun (280 ZX Turbo). When it came out it was state of the art as it was the only standalone to use individual coil packs (GM based). While it is not a "new" thing now, that car revs to 9500 all day long if I ask it to (just as an example of what individual coil packs are capable of).

The real question becomes.....what is the rest of your setup that you think you will benefit from the extra rpms? What cams? What turbo(s)?

With your setup and the cams/springs that Rob is installing you can easily rev to 7500 without incident. Power will have dropped signifantly by that point but IMO, bouncing off the rev limiter , especially during the ultra short 1-> shift is really annoying. My setup will/is nearly identical to yours, I am expecting to set it at 7500 and call it a day. The intent isn't to run that high for any extended period , it's just to avoid popping off the limiter,especially during hard drag launches. Also if Rob tapers the boost off a little above ~7k you will easily feel when it's time to shift and hence not need to fixate upon the tach.

Nano, an 8mm stroke increase is nothing to sneeze at. :D All thing being equal, the VQ30 has a higher rev potential than the VQ35, and my main point is that if power is falling off after 6500rpm, there may be limited benift to reving this motor to 9000rpm without some major mods.