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Think I went with too big of a turbo...

Thread: Think I went with too big of a turbo...

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Posts: 441-450 of 710
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2011-08-28 18:50:19
#441
Google some images of plugs with slight detonation damage on it and you will see what i mean.
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2011-08-28 19:05:37
#442
when i've seen detonation on plugs it looked like someone lightly dusted the ceramic with a spray paint.

The 3076r is a 6-bladed compressor with a large b-width. I think this is what causes the loud whine. It has always done that, on every build I've had. I guess that's just how it sounds. It sounds like that even out of boost, just revving the engine. Most cameras can't pick up the high pitch though.
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2011-08-28 19:06:42
#443
This?




I also remember this site: sparkplugreading
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2011-08-28 19:19:10
#444
It wont be that extreme, thats extended period of it.

Here is a fairly new plug with slight detonation damage on it. You can see the small black speckles on the white insulation. Again this is why you have to shut the motor off right away after a pull. It doesnt take much running time at a richer or good a/f ratio for that small of detonation sign to go away. You will notice the ground strap will be a whitish color and also may have buildup speckles on it if it was decent enough detonation. This is a good way to check. It works every time and will show the slightest signs of it. Best to do it with a brand new set of plugs or make sure yours are clean and the white insulation is clear and clean.
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2011-08-28 19:39:06
#445
^^This is what you're looking for, and the way to do it.

My ground straps are slightly white at the end, but that's about it. I've never seen anything on my insulators.
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2011-08-28 19:43:14
#446
Originally Posted by Coheed
when i've seen detonation on plugs it looked like someone lightly dusted the ceramic with a spray paint.

The 3076r is a 6-bladed compressor with a large b-width. I think this is what causes the loud whine. It has always done that, on every build I've had. I guess that's just how it sounds. It sounds like that even out of boost, just revving the engine. Most cameras can't pick up the high pitch though.


They sound like the monster turbo's you find on larger semi's. The one's that sound like 747's flying up from behind.
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2011-08-28 21:48:46
#447
Originally Posted by Coheed


The VE cams are huge, and not necessarily in just duration. But if you want to get a good idea of how large they are, put some 20w50 oil it it and flip the cams on at idle. The lopey idle is SO rough, the car won't even run. Keeping the idle at 1000rpm you should hear the lope, and it is far worse than S4 cams.

I remember having fun with some friends and kicking the vvl at low rpm and listen to how crazy the lope was. It sounds totally bad ass. But 48* overlap is huge overlap, 20* more than the S4 cams.

The log manifold can work with a VVL. But your results on a DE would likely be a lot better. A DE motor with the same setup and S4 cams will perform better.

To really take advantage of the flow of the VVL head, you must let it breathe. Since the motor is designed for NA, why not take the approach of treating like it is NA? This means taking a look at pressure differentials of intake and exhaust pressures on the NA VE, and getting as close to that ratio on a turbo VE.

If you measure backpressure on the VE engine when NA, you notice that the backpressure is just a little higher than intake pressure at high rpm past peak VE. Take a turbo VE and do the same thing, and you are likely having a lot more pressure on the exhaust than intake. If you are able to get the exhaust pressure down, while maintaining good positive pressure on the intake, you will see huge gains.

Case in point, Miko posted a dyno of his friends car making huge power on low boost on 20V cams. It is all about getting the exhaust side to take advantage of the flow. Too much backpressure and you are unable to scavenge the cylinders properly during that overlap period. Can you still make power? Sure, absolutely! But are you making the most of the engine?

The VE engine will always love big turbos. It does perform similarly to some honda engines. We can take some notes out of their camp and apply them to this engine. You would be amazed how many turbo builds are using NA cams, but they always utilize a free-flowing setup to make good power.

Getting boost pressure higher than backpressure is called crossover. Unity is a term used when volumetric efficiency is at or over 100%. When crossover happens, overunity is often experienced and large gains can be seen. Although, this typically can make the setup very sluggish in response. But sometimes, you can see improved response.

Having unity means having 100% volumetric efficiency, and if you ever plot out your VE on a turbo map, you can see that having a higher VE puts you in a different part of the map. Usually, you are able to utilize a more efficient part of the compressor on lower pressure ratio, with higher adiabatic efficiency, and increase the rate at which the turbo spools.

Imagine the same scenario, with a plugged up exhaust with higher backpressure. As VE drops, you experience a more sluggish turbo that spools later, and that lower VE also results in high pumping losses, and less power.

Solution? Free-flowing turbine, or treat the motor like a turbo motor and get turbo cams. Turbo cams are built to perform under circumstances of higher backpressure. They close the valves in a way to minimize overlap. In these circumstances, you see higher VE with a restrictive exhaust, because you are still able to promote a clean air-charge without reversion or an EGR effect.

If you really want to build a SR20VE, take advantage of its flow over the DE engine. Build, take measurements, log data, and keep the exhaust flowing with the stock cams. Then your power goals will come to fruition.




Perhaps this quote will help others. I do look forward to the end results on this build.
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2011-08-28 22:50:45
#448
VE's love bigger turbos for sure.
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2011-08-29 01:42:26
#449
What would you guys say some safe AFR's are? I saw JP's post on the old forum saying 11-11.3 is safe. I can richen the mixture out to that point and see if that helps avoid detonation.

Originally Posted by jp
safe side 11 to 11.3 best power safe.. 11,5-8 water inject 12 meth 12,2-4
idle 14,7 cruise 15,5
cheers.



Originally Posted by ashtonsser
It wont be that extreme, thats extended period of it.

Here is a fairly new plug with slight detonation damage on it. You can see the small black speckles on the white insulation. Again this is why you have to shut the motor off right away after a pull. It doesnt take much running time at a richer or good a/f ratio for that small of detonation sign to go away. You will notice the ground strap will be a whitish color and also may have buildup speckles on it if it was decent enough detonation. This is a good way to check. It works every time and will show the slightest signs of it. Best to do it with a brand new set of plugs or make sure yours are clean and the white insulation is clear and clean.


Sweet, I'm trying to figure out where I can do this (besides hitting up the dyno).

Originally Posted by Coheed
Perhaps this quote will help others. I do look forward to the end results on this build.


As I was reading through it I was asking, what about stock VET's on restrictive GT25's, but then I saw your comment about turbo cams. Does VET have larger exhaust ports to help with the flow? Is there anything else that VET has that we can learn from?

Also I'm planning on getting a .82 AR housing, and seeing if it will work better, even if I get VET cams. I don't really want to get rid of the log manifold due to fitment and reliability of the manifold.

Originally Posted by P10FTW
VE's love bigger turbos for sure.


Even with the turbo lag, the car still feels great. I think this is because of torquer low lobes and higher comp.
Last edited by Vadim on 2011-08-29 at 01-47-36.
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2011-08-29 02:07:58
#450
Yeah I thought the VET had larger valves. Port design is slightly different. But I've never seen a 20V head. I know they changed the ports slightly, but to what extent I don't really know.
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