He's probably using VQ30 stock injectors is what I'm thinking

 

This is joking right?

 

not sure if you're sarcastic or serious about your question with the vq30 heads fitting the vq35de. . .


the nismo heads are the casts of the vq30 heads with the intake port design from the vq35de. . .

http://www.nismo.co.jp/en/products/c...ne/vq35de.html

 

Interesting. I would have suspected that your new cams would have much higher, faster ramp rates that the OEM cams. Maybe that's just my drag racing roots showing. Your Z doesn't appear to be a drag racer... maybe gentler ramps are in order for a road racer.

I'm not familiar with the acronym SIR. What does SIR stand for?

Thanks a lot for all the information on your motor. It's obvious that you have a few tricks that none of us have heard before. The VQ30 heads is a slick concept.

 

SIR stands for single inlet restrictor. The SCCA uses them to cap HP to equilize classes. And using the vq30 heads is because of easy compression and the larger 35mm lifter bucket. It allows for a larger base circle on the cam. You should look at the stock cams. The ramp is almost flat. So you go from no lift to max lift in very quickly. And then it slams closed almost as quickly. Look at the length of time a long duration cam has to lift the valve open. The valve spring at 7k rpm is working much less to control the valve. Add to that a titanium valve and a lightwieght lifter, and you can see why very little valve spring is needed. So all you guys with the heavy valve spring are just losing HP.
Chris

 

Sort of but it's not all or nothing. There are significant advantages that a steep ramp rate can provide, and it all depends on what the engine is being built for. As far as the springs are concerned, the rpm range coupled with the cam profile itself are what will dictate the proper spring choice is. I have stock valves, stock lifters and cams with a pretty aggressive ramp, and spin the engine alot more than you are, and yet I too don't have to use a very stiff spring (NISMO..which are mild compared to some of the other offerings out there). It's all a balancing act.

 

Proof of stiffer valve springs causing significant HP losses please.



All a stiffer valve spring will do is cause more friction between the lobe and bucket in a bucket tappet system (still nothing compared to the frictional losses caused by the piston rings). There are no other losses involved. I'll take that extra bit of friction and over-rev protection over even the mere possibility of valve bounce, thanks.

 

 

Winning is winning..

 

not true long straights HP is teh win bud. But its a love hate relationship. You cannot really enjoy one without the other my 2cents. lol But on a highway race or top end race. Tq will not guarantee a win at all , you actaully just look good in the beginning of a race until the higher HP car without alot of tq passes you really bad. Every race a turbo diesel with insane tq and not much hp lol. Granted weight is factor but you will eventually pass him. (note beware of turbo diesels biggest sleepers of all time) lol

 

There is no theory to be proven wrong - both hp and torque are important considerations when overall engine performance is concerned. Neither one on it's own is a guarantee of superior performance. Gearing, weight and rpm range play just as important of a role as horsepower and torque do, and in some circles, these things are even more important. Gauging performance without considering all these other factors is interweb racing at it's finest - and is meaningless

 

okay on a top speed run for meaningless talk, ...a high tq car cannot out pace a higher HP car given same gearing car etc. It just doesnt make sense . LOL think about it with the laws of physics lol.

 

HP is all that matters, gearing can make up for lack of torque.

I would be interested to compare the Nismo Spec-2 ported VQ30 head to the cosworth heads. Cosworth has less CC and less compression, however larger valves.

Looking at the rough graphs on Nismo's site and Cosworth's site it looks like the cosworth heads flow more, but so hard to compare two different flow charts to one another.

 

Someone needs to read this...

http://vettenet.org/torquehp.html

and remember, HP is derived from torque, you can't have one without the other.

-------------Torque * RPM

Horsepower =------------

-----------------5252


---------Horsepower * 5252

Torque = -----------------

---------------- RPM

 

Did you make it to the dragstrip to see what 310 horsepower will do?

 

wow, nice but i still like cruising around in mine. good info though