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I just added a qsv but I’m getting the opposite results. I have a stock block vvti s1 cams. Qsv with f1 manifold. S366 1.0 a/r it feels like the motor is chocking until the valve opens.
 

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I'm wondering what you guys are doing for timing on cams and VVTI its really easy to bend all your intake valves with the wrong VVTI settings
 

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I have a stock block with s1 cams and had a short to ground on my vvti oil control valve. The intake cam was advanced to its max position while idling. I did not have any piston to valve or valve to valve contact. If I had higher compression not sure if I’d have been so lucky.
 

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For you guys who switched to a VVTi head, did you also switch the crank gear from the 12-tooth to the 36-minus-2 VVTi gear ? If you did, did you have to change the crank sensor as well ? I seem to remember something about the 12-tooth sensor not being sensitive enough to accurately pick up the finer teeth on the VVTi 36-tooth one.

There's always the expensive PHR Hall-effect sensor kit ($349) ...
Powerhouse Racing Cam and Crank Hall Effect Sensor Kit for 2jz and 1jz
 

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Crank gear must be changed to 36 tooth. I’m still running the oem crank sensor. No issues
 

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Yeah, I was about to post. Chatted with Haltech - they said you have to run the 36-2 wheel, and stock sensor should be OK.

BTW - anyone with Haltech Elite 2500 ? Would love to have a peek at your map ...
 

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Not sure if this has been answered but I have not found anything conclusive in my search on SF or Google. Does the VVTi spool a turbo faster than say a stroker without VVTi? Lets just say a 8.5CR 3.0 w/ VVTi vs a 8.5CR 3.4 w/o VVTi all other things being equal.
 

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Yes.

I went from a 8.5:1 3.0 non-VVTI to 10:1 3.4 VVTi with the same turbo and did some logs without VVTi and the same 80mm turbo didnt spool that much better but when enabling VVTi, 1 bar of boost came 500-750rpm sooner depending on gear and even below that it was a lot more torque.

So I would go VVTi over stroker if I would need to make the pick.
 

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Krister,

Without a 10.0:1 3L motor or an 8.5:1 3.4L stroker, do you think this was an apples to apples comparison?


Ken.
 

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Not exactly of course.. but the point being that even going from 3.0 8.5:1 to 3.4 (3.3 actually with 86.25mm bore) 10:1, I didnt get a dramatic spool difference. Sure, the off boost response was a better but didnt affect on the boost threshold that much. The VVTi was the one that moved the curve to the left by a lot.
 

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Yes.

I went from a 8.5:1 3.0 non-VVTI to 10:1 3.4 VVTi with the same turbo and did some logs without VVTi and the same 80mm turbo didnt spool that much better but when enabling VVTi, 1 bar of boost came 500-750rpm sooner depending on gear and even below that it was a lot more torque.

So I would go VVTi over stroker if I would need to make the pick.
Interesting as most of what I have read stated going up in CR improves spool. So the fact you went from 8.5:1 to a 10.0:1 on top of going to a stroker I would think there would be a noticeable improvement in spool. But your feeling is the switch to VVTi made more of an improvements than the increase in CR and displacement?

Reason I am asking is I am looking at doing a 3.4 stroker w/o VVTi or switching to VVTi but staying with a stock bottom end.
 

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That's my experience atleast. I would do 3.0 VVTi instead of 3.4 non-VVTi. That being said I am building another stroker engine (just because I got the crank for cheap) and also with a VVTi head. But I would have stayed 3.0 unless the crank was a too good of a deal to pass up.

If I were you, I would upgrade at least the rods because they are the weak link and then go VVTi. Because VVTi increases spool and torque you will risk breaking the rods depending the boost / setup you are using.

Here's the spool difference. It's my setup in the same dyno. 3.0 8.5:1 non-vvti vs 3.4 10:1 vvti. On the street the spool difference was bigger. Red is torque and blue is hp.
 

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the VVTi's advantage is free midrange power. You sacrifice nothing for this power, I did back to back pulls with my car (one with the cam advance working and one with it zeroed out) and I picked up 300whp in the mid range only due to the cam advance. you can play the hypothetical games comparing combos until you're blue in the face, the bottom line is if you have a non vvti head and you switch to a vvti head you will make more power under the curve every time.
 

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Here's a good comparison for you all with a 6870. All runs done at 2 bar boost, all with similar specced engines other than differences in capacity & vvti.

Green = Non VVTi 3.0
Red = VVTi 3.0
Blue = VVTi 3.4

Engine static compression will make a slight difference to spool time and will make the engine respond in a more responsive matter, however it does not alter the amount of air being introduced into the cylinder in a noticable fashion. It can just process the combustion in a more efficient manner, which is still important but won't net the same gains as having more air being crammed into cylinder.

Typical to see around 400-700rpm reduction in boost threshold and peak torque by using VVTi and similar reduction again by using a stroker. So if you care about area under the curve then I find it hard to understand why you wouldn't want either or both on your build.
 

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I don't know that anyone was questioning the benefits of a VVTi set-up. I think the benefits are indisputable. My comments related only to the integrity of the "apples to apples" comparisons posted at the time my comments, and others, were made.


Ken.
 

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I will hopefully be self tuning my Fueltech powered VVTI GTE by the end of this year. Someone mentioned above that if you don't know what you're doing tuning wise you could damage the engine with piston/valve contact.

For a completely stock motor with stock cams is this still a possibility? I thought you could use the full 30* range of adjust on the intake cam. I was planning on putting the motor on the dyno and doing 7 pulls starting from a locked 0* to 30* in 5* increments then laying the runs over each other and mapping out the VVTI map that way. I've seen it done on youtube with a K series figured it applies to the 2JZ as well.

Any input on this is very appreciated.
 
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