I always thought tachs over estimated, mine is the opposite .A hair before 8000rpm my fuel was cut.

I know its high but i think everyone does not understand how strong our engines and valvtrain are. Even if it blew on the next rev it still has gone close or at 8000 over 100 times at this point. When my plastic beauty goes on this friday I will rev there even more.

 

Make sure you get plenty of pics of the custom TB/IACV plate.

 

This is good to know. Thanks for exploring the upper rev limits. Now I feel a lot better about taking mine to 7200.

 

BTW, do your valves float?

 

No ,but its weird there seems to be a slight dead spot between 6800-7000rpm and then after that it accelerates pretty good in first. In second gear the highest iv'e been is 7500-7600rpm.
The reason my gears pull at these points is because my car in street trim weighs in the 2700's. I will go to the track after a few weeks. I have BF goodrich drag radials that are going on some 13lb rims this week ,the tires are good for about a 5% gear reduction I think.

 

Valve float is not your friend . . . although I am no expert, I am willing to bet that revving to 8000 more than a few times could cause some internal damage. Have you spoken to a good mechanic who is really familiar with the VQ30DE?

 

I am also no expert but there is no way your car weighs 2700Ibs in street trim. Your definition of street must be radically different than most. Have you actually weighed it? I'd say 2800 is a stretch. Mine was 3120 with half tank and a fair amount of street lightening. I know the auto is heavier but not that much. On a positive note, thanks for testing up there in the stratosphere. I hope TS comes out with extended rev by October.

 

I've got a DE-k sitting in my shop right now. I need to see some pics of the install.

 

Me and a fellew max org. member are doing this on friday at this point for me it is a direct bolt on ,the only thing im worried about is the 2000 injectors working. If they dont I'll take my 96 lower and have it welded and machined to work.

 

hey kris,

have you dyno ur car with JWT 8000rpm? cuz i'm really interested to see how much WHP that VQ30DE produces above 6,500rpm.

 

no i didn't ,i wanted to but with my busy work schedule and the dyno being hundreds of miles away I decided to dyno with the VI on . Maybe a couple weeks to dyno.

 

The stock valvetrain does NOT support what you're doing. I had one of those cars and I know the valves float at about 7500.

 

I believe it does. He's done some pretty drastic weight reduction including getting rid of all the sound deadener, etc. My car is 2850 in street trim and that's with stock hooed even. If I had CF hood, 12lb racing seats on each side, and no subframe connectors, my car would be 2730 in street trim, with all my stuff in the trunk still in there, and that's without the drastic sort of things he's done like removing sound deadener.

 

i think the 7200 rpm rev limiter for TS is already high.... I can't even think about going to 8k rpm

 

Who said the valvetrain was stock?

 

Who said it wasn't?

 

thx kris keep us posted...

 

I guess I stand corrected in a way. I don't consider removing sound deadening something that I'd do to a daily driver or street trimmed car. How much do SFC's weigh?

 

Well i dont know of any VQ that can handle anything more than 7500 RPM repeatedly with the stock valvetrain so he must have upgraded something, I.E. springs and/or retainers. This coupled with the fact that the VQ30 has a shorter stroke than the NSX (the highest revving V6 that I know of), and most 4-cylinders for that matter, and that is has the valvetrain design with the least rotating mass leads me to believe that excessive piston speed and valvetrain stress wont be issues. We'll see if the crank can handle it over time though...

 

Wow krismax I remember when you told me about the VI plans back in December when I picked up those racing seats from you. You've come a long way (since it's all down to bolting it), I can't way to hear how the final product performs. Way to be a pioneer man!
-Cyrus

 

Why wouldn't they?

They will fit because you're using a 2000 LIM and fuel rail plus your ECU will handle staturation type high impedance injectors. You just may need to lower fuel pressure a bit, since you're going from 240/260cc to 290cc injectors.

 

Where is this statements basis?

I've talked with him many times and have got nothing but the complete opposite impression. He has put considerable thought and time into his -K manifold project and I believe will be successful soon.

As for the valvetrain, show me a VQ30DE dyno with valve float please.

 

BTW, krismax I'll have those torque specs to you shortly...just been busy.

 

Valve float won't be an issue in gears 1 or 2 because you spend very little time above 7000rpms. However, in gear 3 and 4 he'd better watch his butt because the motor spends a lot more time accelerating thru the rpms. Valve float is definitely are serious issue, but what about:

1) a spun crank bearing
2) clutch
3) accessories
4) rods

All these components need some serious attention when revving that high. Even with an upgraded valvetrain (which he doesn't have), I would never risk it. There is a limit to how high you can rev a motor, especially one that was only designed for 6500rpm operation. If the VQs were such high revvers, I think Nissan would have expanded the rev limiter a little further, especially on the Z/G35. All the VQ generations have been stuck with 6500rpm limiters. 7200-7300rpms is about as hard as I'd push any VQ. Just my opinion.

As for the "street trim" weight of 2700lbs, I guess it's possible assuming he's done some weight reduction. My 96 SE 5 speed, BOSE, moonroof, and power seat weighed in at ~3020lbs. That was on a CAT scale which is a certified and insured scale which means they typically weigh 4-5% heavy. My 3020lb weight was with over a 1/2 tank of gas (60lbs), spare/jack (25lbs), subframe connectors (25lbs), tools and various work related gear (30lbs).


Dave

 

I agree mostly with what you said.

However, the VQ35s are limited to 6600rpm because of it's considerably longer stroke AND increased rotating mass. Also, the TechnoSquare VQ35s with their 7200rpm limiter has an equivalent piston speed to a VQ30 at 8000rpm, so with the lighter internals, I'd say it's not TOO extreme.

Piston Speed:
VQ35@6600rpm ~3524fps
VQ30@7330rpm ~3525fps

VQ35@7200rpm ~3844fps
VQ30@8000rpm ~3847fps

 

Thanks for everything you helped me alot on this project.

 

If valve float is not an issue in 1st or 2nd, how does it become an issue in a higher gear? I don't think it depends on time spent at a certain rpm, does it? Or maybe I misunderstood you.

 

Focking PS printer isn't working, so I can't convert to pdf from the FSM...still trying to figure out a way around it.

If you got a fax number, let me know via PM.

 

Those numbers look good

Now for my engine having almost 200,000 miles on it. If it has taken 100+ times reving from 7500-8000 rpm and still sounds great, imagine a 2000-2001 engine with lighter internals stock ,aftermarket springs retainers maybe valves. And some cams with 2000 VI fully operational. This is what i'm doing.

 

i definitely want to see this.

 

It has to do with the time you're spending accelerating thru the 7000+ rpms. In 1st and 2nd, you're spending very little time in that rpm range. But in 3rd and the higher gears, you're spending multiple seconds accelerating from 7000-8000rpms and this is where valve float can become a destructive problem. It's not to say 1st or 2nd gear valve float couldn't happen, but it's far more likely in the longer gears. It's much the same thing with turbo cars and detonation. Most turbo guys don't blow their motors with detonation in the shorter gears, instead they end up blowing the motor with the longer gears because the detonation is prolonged.

Another problem I see is how long legged the gears will become. I haven't done the math, but I know with my 7000rpms limiter, I'm grabbing 1-2 at around ~46mph, 2-3 at ~74mph, and 3-4 at ~103mph. IMO, the gearing of 4th gen with the MEVI/JWT ECU becomes way too long for ideal acceleration. With the way my car revs, I need at least a 4.20-4.30 gear, not the 3.80 gear we have. The 3.80 is ideal for the stock DE motor, but not with the MEVI/JWT ECU. With an 8000rpm limiter I'd think the 1-2 would occur around 51-52mph, 2-3 at 82mph, and 3-4 at 112mph. That's way too long.


Dave

 

I was under the impression that the DE-K short block was no different than the DE short block. It was the cams, injectors, and manifold that changed.


Dave

 

I can see how time in a particular gear affects detonation in forced induction engines. There it's a matter of heat buildup vs. heat rejection rate, so time is a factor. But with valve float it's a matter of inertial forces vs the spring force, and that is wholly rpm dependent and not time dependent. As soon as you get to a certain rpm your valves will float because the spring rate is insufficient to force the valve to stay in contact with the cam. Unless there is a temperature buildup involved, then it would be time dependent, but I've never heard that that is the case.

 

Another problem I see is how long legged the gears will become. I haven't done the math, but I know with my 7000rpms limiter, I'm grabbing 1-2 at around ~46mph, 2-3 at ~74mph, and 3-4 at ~103mph. IMO, the gearing of 4th gen with the MEVI/JWT ECU becomes way too long for ideal acceleration. With the way my car revs, I need at least a 4.20-4.30 gear, not the 3.80 gear we have. The 3.80 is ideal for the stock DE motor, but not with the MEVI/JWT ECU. With an 8000rpm limiter I'd think the 1-2 would occur around 51-52mph, 2-3 at 82mph, and 3-4 at 112mph. That's way too long.


Dave[/QUOTE]I solved the problem with the high gearing today. Its probably around 4.20-4.30 now Feels good

 

But doesn't it look really silly with really short tires?


Dave

 

I suppose now would be as good a time as any to throw some un-needed gas into the fire.

The VQ20DE used the same 73.3mm crank as the VQ30DE, however the new VQ23DE uses a 69mm crank. If someone with too much time and money on their hands wanted to try something different they could put the VQ23 crank in a VQ35 and get a 2966 cc engine that would rev to 8500 rpm to reach 3848fpm.

The equation for calculating feet per min is:

Metric:

FPM = (stroke x rpm) / 152.4
ex: (81.4mm x 7200) / 152.4 = 3845.67 (VQ35DE)

Inches:

FPM = (stroke x rpm) / 6

ex: (3.0" x 6500) / 6 = 3250 (Ford 302)

Also, the 3850fpm is just an example. It may or may not be the max allowable average piston speed on these engines. Stock SR20DEs can go to 4514fpm all day. (86mm x 8000)



http://www.poweredbynissan.com/Engin...ngineSpecs.htm

 

I don't have the actual information sitting in front of me but I am pretty sure they changed a small amount of internal parts as well. I will have to look it up to see exactly what was changed.

edit: fresh alloy says that 50% of the engine's internal components were redesigned.

 

In short, I'm not concerned about the bottom end, ie stretching a rod or spinning a bearing.

The valve springs are a concern, but honestly why not try and see where it floats, then buy the upgrades.

 

Sure, don't be concerned about someone elses engine. Why don't you do something constructive and blow up your own engine first. Then you tell us all about it.

 

Be aware that this assumes that pi = 3. Kinda rough, but easy to use when figuring out piston speed in your head.