Revving to 9k rpm

[nimblestix]

Been researching through google, and tried a little search on GTRC. Came to the conclusion there's a lot of people that don't rev past at the most 8500rpm, and then there are a few rock stars out there revving to 10k! This is why I've come to you.

So, now that I've been to the track a few times (drag strip) I've been analizing my footage and logs and from what I can tell, without changing to different tires (currently on street dz101's) or upping the power of my ~500whp gtr (pump gas) that maybe drawing out the gears a bit could help me to get into low 11's or even high 10's.

Right now I can consistently attain 11.7 second passes @~120mph without mashing the gearbox too hard. I'm shifting at 8200 rpm currently and having to shift into 4th before crossing the line losing precious time. I'm thinking if I can hold it until 9000 in 1st,2nd,3rd I might just pickup a few tenth's. (I'm still pretty new to the track)

So, currently I have a fully built bottom end (carillo pro rods/bolts, 87mm wiseco pistons/pins, acl race bearings, lightened & balanced r34 crank and trust extended sump), 1000hp ati damper, tomei re-inforced timing belt, jun oil pump n1 water pump, and as far as the head goes, fully ported, small oil orifice, new oem guides, seals, valves adjusted to spec, stock springs, stock valves, 264/264 9.25 lift cams. And a sweet a$$ Borg Warner turbo.

Basically in your opinion if I install a set of type b springs or some other stiffer springs do you think this will suffice @ 9k?

Thanks guys!
Eagerly awaiting your responses.

FWIW this is home built baby!

Brent.

[kengeroo]

was wondering this also,, I have a similar build and my ECU rev-limits at 7500,,, (sissy),,, waiting for the new MAFS to balance out the rest of the built engine...

[Black BNR32]

http://locost7.info/gearcalc.php

I'd say go for it. But, expect a bigger bang for your buck by working on your 60 foot times.

[nimblestix]

Definitely working on my launch would yield some of the most gains, although I'm currently holding a consistent 1.8s 60' which I believe to be fair on street tires?

[nimblestix]

http://locost7.info/gearcalc.php

I'd say go for it. But, expect a bigger bang for your buck by working on your 60 foot times.

That is an amazing tool you have provided. Thank you!

[bourquetc]

My best 60' is 1.79 im only at 330hp launching at 6900rpm

[Dragon Humper]

You should be able to wind her out more in 3rd but, if you are shifting into 4th at the 1000 to 1100 ft mark you aren't losing much time. Trap speed will suffer a little but time wise you are only giving up a tenth...maybe. The 3-4 shift happens very quick, much quicker than any other. The 60' and the 1-2, 2-3 shift will get you more tenths. Most of your ET is made in the first 1/8th of a mile with the 330ft being the most critical, the rest is just keeping the engine from crapping out and killing it all. I have seen medium HP cars go 11 flat at only 115 mph just because they can crank off a 1.3 sec 60'.

Edit....
I looked back at some of my time slips from a while back and on two back to back runs I had identical 60's, a 1.827 and a 1.828. My 330 was 4.860 and a 5.002. Same launch but quicker shifting and not wandering around as much knocked 2 tenths off my ET. 11.438 vs an 11.242. I did that on the laughable 225 16s that were on the car when I got it.


If you can stomach it, take her out the back door in 3rd on a good run and see if the MPH improves, if it doesn't, you don't need to do that. If you can lop 2 tenths off your 60' that is worth over 3 tenths in ET.



Jon.

[nimblestix]

One of the details I left out about my power band is that it continues to rise even at 8000, there is no drop so I imagine that I could still be utilizing the power for that last 1000. Ill post a dyno sheet tomorrow when I have one. Currently I rev her to 8200 in third (rev limiter) & its still pulling harrrrrrrd.

So would you agree that if someone wanted to rev to 9 on my setup, all that's needed is a good set of springs? Or would you suggest anything else?

Cheers!

[caliber676]

i would change at least the springs and research into making sure you pick the right spring so you don't float a valve. I know having your crankshaft balanced for your peak rpm is a good idea but would be hard in your case. (its like having a tire that is balanced and rotates fine at 80km/h but vibrates at 120km/h)

if your pulling the head, might as well get some stronger valves and guides/retainers. I've heard of heads decimating the guides from high revs/too much heat.

there are a lot of ifs and buts. I'm the type of guy that will replace everything if i have the chance because im paranoid it will break. some will do the basics.

[gtrkrauss]

stiffer springs for 9000 my friend. Youll be happy you went that route to avoid floating. The bottom end isnt the problem. Whats your suspension set up? if you can get your 60' trap down to a 1.50 you will be in your target 1/4. You might be looking towards playing with suspension settings rather than winding her out an extra couple hundred rpm.

[nimblestix]

I'm a lot like you caliber when it comes to replacing parts. However this time the plan is to replace the springs/retainers with the head still on. I plan to pressurize the cyl to hold the valves closed and swap the springs. This engine build has around 5000 kms on it and everything was inspected prior to assembly. Valves were good shape and it received all new guides and seals at the same time.

Cheers!

I'm going to try and use the lightest spring possible for my goal to avoid any excessive wear to the cams. So far I've been thinking of using the tomei Type b spring and retainer kit, should mate nicely with my older generation type b poncams.

[nimblestix]

stiffer springs for 9000 my friend. Youll be happy you went that route to avoid floating. The bottom end isnt the problem. Whats your suspension set up? if you can get your 60' trap down to a 1.50 you will be in your target 1/4. You might be looking towards playing with suspension settings rather than winding her out an extra couple hundred rpm.

Again some important details ive left out.
Early in the night I was running way too high of a tire pressure @ 35psi, after lowering it to 25psi I could grab a lot more and started running the 11.7-11.8s but due to the added traction my launch control of 6400 wasn't high enough which caused me to bog out of the hole. When I return for the next night, I plan to try running my tires at 28psi and adjusting my launch control by adding a little bit of anti-lag so I'm boosting around 10psi out of the hole.

Cheers!

[Skym]

Just holding onto the gear to keep engine at peak hp is enough. On one R32GTR I know of, it went from low 11's to high 10's by just holding onto gear over the line vs changing up a gear.

Higher rpm = more load on conrod bolts, conrods, bearings. Just 1000rpm more is something like 3.5 ton (not exact figures, but you get what I mean by extra load on conrods, conrod bolts, bearings). Search for info on "inertial load" and the result's of too much inertial load.

Also it doesn't matter that they are H beam conrods, as H beam conrods can take slightly more load than I beam and still suffer the same problem (snap like a twig and put a hole in side of block). Go look at the high reving, high hp EVO drag engines and see what they have done with conrod design, etc to make the engine handle higher rpm. It gets expensive very quick.

Also using stock valve guides that will crack at higher than stock rev limit. Tomei bronze valve guides are needed, HKS valve seals.

If want better 1/4 mile, dial in the rear of car. When the rear squats it creates more camber and less tyre contact patch. Using stock rideheight can help to reduce this and adjusting camber via adjustable arms when rear squats can help to gain traction. Skylines are setup for track, not dragstrip. Adjusting rear subframe angle (Whiteline pineapple bushes) can help with traction. Also don't forget adjust damping on shocks. Usually stock suspension setup is best for drag racing, as allows the correct transfer of weight to rear when accelerating.

Also you will get higher trapseeds and lower 1/4 mile time if you feed the rear of car with more hp (more rearward bias), but car is more stable with more front bias and sacrifice trapspeed, 1/4 mile time. Veilside sold a pump action 4wd adjuster just for this task. Or buy a Field or similar torque split controller and see if can run more rearward bias. Gear dependent boost control (Apexi AVC-R can do this) can help as well, as run low boost off the line and increase boost level in each gear.

Try launching off the handbrake which helps to reduce wheelspin (takes a bit of practice, but from what I have seen, is a common technique when launching GTR's in Japan).

Also use stock R32 GTR rims, as they are very light, around 6.5kg each (vs 17kg for some aftermarket bigger diameter wheels) with drag slicks. They work on mid 8 sec R32 GTR dragcars.

If used above part's, etc, should be an easy high to mid 10 sec car.

[collector240sx]

I agree with what Skym just said above.

Preloading the drive line to limit the shock on your drive line is a very good thing.

And about the spring in the head, changing them is a good thing but don't think that putting the stiffest spring out there is going to be you best choice. The stiffer the spring the more wear you,ll see on your cam, etc...

If you want to have a look at an RB26 that has seen 10k rpm. there's video on his web site. I know it hasn't been updated in a while. I wonder if this car even still exist. I do know he had a stock Getrag box in the vid and did destroy the syncro for third gear.

http://www.kismo.dk/

Got some pics of the build and the specs of the engine and head. This was my inspiration for my build but decided I didn't want to pay the money for a hollinger, and I don't need 4 wheel drive. So if I get a decent price for the GTR stilll going to build the engine, it's just going to go into something else and have it rear wheel drive.

[tryingtobebest]

Hi, I have no build thread around this forum because lately im being a bit lazy with my GTR...

I have rev limiter set on my Haltech at 9k with around 300 drop, which means i can REALLY catch it when it hit and that would be enough time for me to react and slam next gear. Here is my build in a simple way:
Wiseco/Eage/ACL/Cometic/HKS 264 - 9.1/ Supertech Dual Valve Springs/ Greddy RAD, Timing Belt, extended sump/ OEM Balancer/ BW S372 with 1.10 ar ex housing/ FullRace Ex Mani with dual Tial 44's *atmospheric*/ Kinda restrictive exhaust - 4" down to past cat and "HKS" system with really good and huge resonator after(Extremely quite)/ Haltech ECU tuned by myself (IM not a tuner, but im a mechanic)/ Brand New R34 Crank from Nismoportats.com/ Rotating assembly - balanced by myself in the garage, as well as the pistons prepped, valves - seat grind to the head and there is porting of the head on the exhaust side only (expanding and removing that hump)

My best result was 11.5 (out of 2 tries ever, and not familiar with the ride) DRIVING OFF THE LINE at around 16 psi of boost, I never experiment with LAUNCH CONTROL, full boost is around 5.5k. Im still on the stock inectors/rail/lines/pump they are maxed out after 7.5 - 8 k on the COOL day, A/F ratio is climbing up to right around 12.8. This set up lasted me for about a year during which i put 5k km, but everytime im driving the car there is 5 to 20 - 1 through 4 gear accelerations. Oh, forget to mention OEM (NOT N1) oil pump with pretty large custom oil cooler and 15/50 Mobil 1!

EVEN to me what I just wrote sounds CRAZY but this set up is working for me, after i upgrade: 1 COILS, 2 custom fuel set up, 3 straigth exhaust 4 proper tuning and im swithching to 10k because that turbo is INSANE

So to answer you question YES if you install some good springs you should be good, i don't think i have half of your parts and im rving higher!) I do not recommend you to go with "LARGER" valves or any aftermarket valves or guides at all.
BTW what kind of BW do you have? You don't have a build thread either!?)

Oh, HERE IS the funny thread to check out.

My 11.5 run (Where you can see how much im bogging down at the start)