Vtec shouldn't be at 6 or 7k in any setup. Where did you get this kind of info? I ran a log and engaged at 4500. Vtec engagement will vary with every single car for a few different reasons.

The reason I continue to push a log to a NEW guy is it's hassle free, and CHEAP, meaning he won't skimp on other cheap parts that will cause a failure to his car. I'd rather see him use quality components and have less problems then screw himself.

 

 

I made my statement based on facts and from personal experience. Do a search on this site and you will find the same info.

 

when i had a pfab log mani and 60-1, the damn car hated vtec at 4500. it didnt smooth out and make power till John set it at like 6100 rpm.

he said the s2000 with the sidewinder type mani that he tuned the week before mine(this was all like 3 years ago) liked vtec down in the 4300 range.

My stage 2 SOS i have now likes vtec at 4700.

 

Let me rephrase and say I don't believe that it should be much higher than 6k in any setup but still 7k seems a bit outrageous. I'll do some searching to see who's running vtec up in those limits as you suggested because reading never hurts.

There's a lot of factors that will change Vtec. Still to say a rule such as all logs should be in 6-7k seems a bit much.

As far as 6-7k, I'm looking at it from this perspective, the stock motor has valves at a given size that open at a given time to allow stock airflow volume in and out of the motor.

We as FI owners are moving more air than stock across the board in a turbo setup, to see Vtec at 7k on a turbo setup I'd be looking at what else is very wrong with the tune.

6K I can understand, my setup with a log has been near that but has also been successful down to 4500.


-G

 

Ive seem alot of turbo dyno graphs were very skilled tuners have to set Vtec up in the 6-7K range. If you look at Log type turbo setup were vtec was set in the 3-5K range then you will see the jump in power after vtec has already been engaged for ~2-3K RPM's

Now I've never owned a turbo car but I do alot of thread trolling

 

In the 7k range really? I'm not doubting you but this sounds a bit surprising to me.

I do know of the jump you're speaking a bout, I've seen that many times as well but I also have seen it not occur in ranges around 4500 on logs. To explain the differences is perhaps where the rule should be made then.

It's surprising to me that nobody has mentioned load or other factors. If people are talking about an engagement occurring at say 6500 in a certain condition I could see that and find it reasonable. I'm assuming we're talking WOT.

That said, again, we should be considering numerous factors, my engagement is dependent on load, rpm, etc. Vtec engagement SHOULD be smooth on the dyno chart if set properly from my experience

In the most basic of principals an engine is just a air pump with fuel added. Air in and Air out are the primary factors in hp made, to flow more air we need larger holes, thus Vtec get's lower along with higher tq setups.

Now, perhaps I'm overlooking various dyno sheets because they were of no interest to me. I could see Vtec being high in this circumstance, a huge turbo with a massive FMIC and massive piping hooked to a inefficient log manifold. That would perhaps call for a very late Vtec engagement of 6500k or even higher because on the bottom the end the thing is gutless. Still higher than stock?

Can you guys post some setups with dyno graphs? Now I'm curious about how/why setups exist like this.

 

Just a few I found

 

I agree with this, but with a 5858. Should make 500+ on 1 bar and can make 600+ if you really push it. Precision's new 58 wheel is pretty kick ass.

 

you know manifolds go off inside diameter right, since it's schedule material. 99% of s2k manifolds are 1-1/2" material, where as headers are more than likely 1-5/8" or 1-7/8". so in a way you're right, you just don't know what you're looking at.