450sx part 2

[gsracer]

Im running regular coppers one heat range colder. In either case I'm gonna go with iridiums bkr6eix should work fine in the application.

I dug a little deeper and realized what the problem, For some reason when i would give it just 1 degree of timing more at 6000+rpm , the battery voltage would drop drastically to 11.5 volts, the super charger belt and the alternator belt are on the same pulley.

Its really strange, i have two logs with the same occurrence when i add the timing, i think the belt is slipping on the crankshaft. The belt is pretty old so I'm gonna change the belt and the plugs and do some logs and see if it gets better.

[mau5trap]

I hated v8's until I saw this thread

[JDMRIDDAZ]

hey jerry
u can jump alt to main positive terminal
it may help

[turbociv910]

Originally Posted by JDMRIDDAZ

hey jerry
u can jump alt to main positive terminal
it may help

not if the belts not turning the pulley.

[blueshark123]

Idk if anyone said this but did you do a ls swap in it haha. Thats the first that pops in my head when i see this motor with that manifold.

[SicBastard]

Belt slippage doesn't make a lot of sense. That supercharger takes >25 horsepower to turn, the alternator takes <8 hp. If there's enough tension on the belt to keep the supercharger making boost, then there's definitely enough tension to keep the alternator spinning. Also, alternators are designed to make their full rated amps at idle. So they should have no trouble at 6000 rpm even if the belt is slipping a ton.

[gsracer]

Then I'm at a loss, maybe the alternator is going out? Its charging 13.2 volts at idle, that seems a little low.

[turbociv910]

is boost dropping also? do you have a map sensor to log?

[SicBastard]

Originally Posted by gsracer

Then I'm at a loss, maybe the alternator is going out? Its charging 13.2 volts at idle, that seems a little low.

Yeah, it should be a little closer to 14.0 volts.

[gsracer]

well in typical fashion with me, after hours of work it was something simple.

3.5 hrs of changing alternators, redoing belts , tensioners, and what not. Still 12.8-13.0 volts at idle. Long story short, main fuse box power wire was loose, tightened the stud, voltage at 14.1 volts.
ARGGGG.

of course said wire was buried behind the dashboard and a nightmare to get to.

[Yellow4g63]

LoL I hate when that happens.

[epik1]

damn this has been an epic 19 pages sir, hats off to you. Nothing but results!

[gsracer]

ok so final results...

Everything was sorted, no more misfiring. It doesn't make any more peak power than before.... just more power everywhere else thats not the peak. I threw timing fuel, etc nothing would increase. Seems like I'm at the limit of the cams at this point, theres nothing more that could be choking it at this point other than the tiny cams...

heres the results






heres a comparison on paper... made 45whp peak and about 48wftlbs tq increase in the mid range and top end. Not bad in the end in my opinion. Average power increase was 30hp and about 30ftlbs to the wheels everywhere in the power band.





and just for fun heres a video on the way home from the dyno, notice the wheel spin in 3rd gear from a 60mph roll all the way to 90mph... awesome. lol

[Chamb-O]

freakin cool man
great idea about the manifold

[SicBastard]

So are you finally happy with the power? Are you going to leave it alone, or are you already saving up for cams?

[gsracer]

um i guess lol... not. Ill probably leave it alone for a while, till i get bored again.

As for the cams... you mean these custom 272 duration 12.5mm lift with custom titanium retainers and super tech valve springs that have been sitting on a shelf in my garage for two years collecting wd40 and dust because I'm too lazy to install them... haha lol

[SicBastard]

You just had the intake off, and retuned, and never thought to take the extra two hours to install those!!! WTF?! In the video it looks like you're shifting at 7200 rpm. How much higher will you push it with the new valvetrain? Is the long block stock?

[gsracer]

lol.. if it was 2 hrs, it would be done by now. Unfortunatly to change the heads, because of the headers, the motor has to come out of the car. Its just a pain. I also have head studs and such to go with it.

The long block in the car is stock. Redline is set at 7100rpms.

The heads are good to 8000-8500rpms so i was told, so if i ever blow it, ill open up the clearances on the rods an mains, install arp rod bolts and see what happens. Lots of people don't know but the bottom end on this motor is 6 bolt main, 4 studs and two bolts coming in from the side with a huge girdle stock.

Bit of mis-information on my part, its been so long, i thought the new cams where 12.7 there not, there smaller..

Heres the specs between stock and my new ones.
stock
Advertised Duration 240* Intake, 240* Exhaust
Duration @ 0.050" lift 177* Intake, 176* Exhaust
Maximum valve lift 0.368" Intake, 0.355" Exhaust


new cams
Advertised Duration 272* Intake, 272* Exhaust
Duration @ 0.050" lift 185* Intake, 185* Exhaust
Maximum valve lift 0.420" Intake, 0.405" Exhaust

[SicBastard]

8500 rpm is only 4612 f/s average piston speed. The stroke is so short (3.256"), and the rods and crank are forged, I don't think 8500 rpm will be a problem at all for the bottom end.

Here's some average piston speed calculations that I made for the 4.0" stroker crank that's going in my LSx on the left. On the right gives you something to compare piston speeds to. Most engine builders say to stay under 5000 fpm for a high quality fully forged bottom end as a rule of thumb.

RPM FPM
7000 4666 LS7 (stock with titanium valves and rods)
7200 4800 Modern F1 (1.6" stroke at 18000 max rpm)
7500 5000 Honda b16 at 9900 rpm
7650 5100 R07 Nascar engine
8200 5466 Tosto Drag machine

[SicBastard]

Also are you sure on those cam stats? The modern comp cams lobes have .050" durations that are only ~50 degrees less than their .006" (advertised) durations. Your difference of ~90 degrees seems really strange and lazy. Who spec'd and ground those lobes for you?

[gsracer]

It was franklin camshafts in new zealand.. .down there these motors are fairly common in dirt sprint cars, maybe it has to do with the VTC in the head. I don't really know much other than that.


Its per there page with the exception that the lift was a custom profile.

Nissan - Camshaft Profiles

[SicBastard]

Originally Posted by gsracer

It was franklin camshafts in new zealand.. .down there these motors are fairly common in dirt sprint cars, maybe it has to do with the VTC in the head. I don't really know much other than that.


Its per there page with the exception that the lift was a custom profile.

Nissan - Camshaft Profiles

Yeah their RB and SR profiles look much more traditional. Probably VTC like you said or limits of the hydraulic lifters. Is your VTC functional and tuneable?

[gsracer]

yes it is, i can pretty much set it to do whatever i want... its worth a lot of tq under 4500 rpm... it gives something like 20 degrees of overlap on unto 4500 rpms when it switches off and goes to close to zero over lap, above. At least thats where i have it set now.

Unfortunately i can't control how many degrees of overlap it will give, its basically an on or off switch. Ive tried both ways, fully on till 6000 rpm and fully off, and where the two dyno plots intersected i went about 300 rpms above that and set that as the crossover point.

Ive probably logged close to 100 pulls and 4-5 hrs on the dyno with this car trying different things

[k0013]

wow man you've got to have one of the most tested and tuned street VH's in the country! Just want you to know your hard work is not going un-noticed. Your laying the groundwork for a new movement in the S chassis community in America. thanks bro!

[k0013]

On a side note, I remember long ago when you built that thing the first time and you got those cams, shortly after you put them up for sale because i guess you had decided you didn't need them because you were going to boost the VH. never got an answer back when i asked if you were still going to part with them a little while ago. guess this is my answer! lol! keep on truckin man! I love this ongoing build!

[SicBastard]

Originally Posted by k0013

wow man you've got to have one of the most tested and tuned street VH's in the country! Just want you to know your hard work is not going un-noticed. Your laying the groundwork for a new movement in the S chassis community in America. thanks bro!

I don't think the VH is going to catch on. It never came with a manual transmission, so you need a expensive adapter. And the newer VQ makes more horsepower with only 2/3 the discplacement! And if you're not a Nissan loyalist the LS just makes so much sense. It is fun to watch oddball stuff like this progress though!

[gsracer]

Thanks for the compliments, over on our forum we have quite a few swaps going on, i think theres at least 50+ vh cars now but...

Originally Posted by SicBastard

]And if you're not a Nissan loyalist the LS just makes so much sense. It is fun to watch oddball stuff like this progress though!

what he said.....

[n8RPS13]

I still plan on doing this swap in a vert or a coupe once I move back.

[bardabe]

haha thanks for the shout out, i just installed another HPX 3.5" and worked wonderful i think you just got a bad MAF man, reguardless car is running awesome. i think the 272's will max out the lightning maf lol

[turbociv910]

Originally Posted by SicBastard

I don't think the VH is going to catch on. It never came with a manual transmission, so you need a expensive adapter. And the newer VQ makes more horsepower with only 2/3 the discplacement! And if you're not a Nissan loyalist the LS just makes so much sense. It is fun to watch oddball stuff like this progress though!

the VQ35 is a rice box when it comes to exhaust note, id take the vh just cuz it sounds cool. Though the sound of a cammed LS